Thread (6 messages) 6 messages, 2 authors, 2021-05-15

Re: [PATCH v1 1/2] iio: adc: driver for texas instruments ads7142

From: Alexandru Ardelean <hidden>
Date: 2021-05-14 08:50:17
Also in: linux-iio, lkml

On Fri, May 14, 2021 at 1:52 AM Jozsef Horvath [off-list ref] wrote:
This is an iio driver for
 Texas Instruments ADS7142 dual-channel, programmable sensor monitor.
Hey,

Looks good overall.
Some comments inline.
quoted hunk ↗ jump to hunk
All of the data buffer modes, supported by the device are selectable
 over sysfs:
  /sys/bus/iio/devices/iio:deviceX/buffer_mode

Data buffer operation modes:
  - start_burst:
    In triggered buffer preenable hook: not relevant.
    In trigger handler: the driver selects the autonomous monitoring
      (see chapter 7.4.3 in datasheet) operation mode,
          configures the channels in sequencer as specified by
      sysfs(scan_elements/in_voltageY_en),
          sets the data buffer mode to "Start Burst Mode",
      then starts the conversion.
    In irq handler: the driver pushes the conversion results received
      from the device to the buffer,
      then restarts the conversion like in trigger handler.
    Both IRQ and trigger are required to support this mode.
    See chapter 7.4.3.2.1 "Autonomous Mode with Start Burst"
    in datasheet.
  - stop_burst:
    In triggered buffer preenable hook: the driver selects the
      autonomous monitoring (see chapter 7.4.3 in datasheet)
      operation mode,
      configures the channels in sequencer as
      specified by sysfs(scan_elements/in_voltageY_en),
          sets the data buffer mode to "Stop Burst Mode",
      then starts the conversion.
    In trigger handler: the driver pushes the conversion results received
      from the device to the buffer,
          then restarts the conversion like in preenable hook.
    In irq handler: not relevant.
    Trigger is required to support this mode.
    See chapter 7.4.3.2.2 "Autonomous Mode with Stop Burst"
    in datasheet.
  - pre_alert:
    In triggered buffer preenable hook: the driver selects the autonomous
      monitoring (see chapter 7.4.3 in datasheet) operation mode,
      configures the channels in sequencer
        as specified by sysfs(scan_elements/in_voltageY_en),
      configures the digital window comparator and alert flags,
          sets the data buffer mode to "Pre Alert Data Mode",
      then starts the conversion.
    In trigger handler: not relevant.
    In irq handler: the driver pushes the conversion results received
      from the device to the buffer,
      then restarts the conversion like in preenable hook.
    IRQ is required to support this mode.
    See chapter 7.4.3.1.1 "Autonomous Mode with Pre Alert Data"
    in datasheet
  - post_alert:
    The operations are same like in pre_alert mode,
      except the data buffer mode selection, the selected mode is
      "Post Alert Data Mode".
    See chapter 7.4.3.1.2 "Autonomous Mode with Post Alert Data"
    in datasheet

The in_voltageY_raw can be used, if the buffering mode is not enabled
 in sysfs(buffer/enable).
 The driver initiates a single conversion in the device for each
 read request(in_voltageY_raw).
 This is a one-shot conversion.
 See chapter 7.4.2.2 "Manual Mode with AUTO Sequence" in datasheet.

Datasheet: https://www.ti.com/lit/ds/symlink/ads7142.pdf

Signed-off-by: Jozsef Horvath <redacted>
---

changes v1
  - All of the buffer opertaion modes
    (pre_alert, post_alert, start_burst, stop_burst)
        are added
  - Added triggered buffer
  - Added buffer operation mode selection sysfs support
  - Redundant parameters (ti,threshold-rising, etc.)
    are removed
  - Supply name changed(vref -> avdd)
  - Added dvdd supply
  - Added device sampling rate calculation
  - Use device-managed functions for regulator, iio device register
    and triggered buffer
---
 .../ABI/testing/sysfs-bus-iio-adc-ti-ads7142  |   11 +
 MAINTAINERS                                   |    7 +
 drivers/iio/adc/Kconfig                       |   13 +
 drivers/iio/adc/Makefile                      |    1 +
 drivers/iio/adc/ti-ads7142.c                  | 1469 +++++++++++++++++
 5 files changed, 1501 insertions(+)
 create mode 100644 Documentation/ABI/testing/sysfs-bus-iio-adc-ti-ads7142
 create mode 100644 drivers/iio/adc/ti-ads7142.c
diff --git a/Documentation/ABI/testing/sysfs-bus-iio-adc-ti-ads7142 b/Documentation/ABI/testing/sysfs-bus-iio-adc-ti-ads7142
new file mode 100644
index 000000000000..7de69a4819e5
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-bus-iio-adc-ti-ads7142
@@ -0,0 +1,11 @@
+What:          /sys/bus/iio/devices/iio:deviceX/buffer_mode_available
+Date:          Maa 2021
+KernelVersion: 5.13
+Contact:       info@ministro.hu
+Description:   List all available buffer_mode settings.
+
+What:          /sys/bus/iio/devices/iio:deviceX/buffer_mode
+Date:          Maa 2021
+KernelVersion: 5.13
+Contact:       info@ministro.hu
+Description:   Sets up the device data buffer mode.
diff --git a/MAINTAINERS b/MAINTAINERS
index ba0cc0a67b32..9acc64ed54e1 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -18084,6 +18084,13 @@ T:     git git://github.com/czankel/xtensa-linux.git
 F:     arch/xtensa/
 F:     drivers/irqchip/irq-xtensa-*

+TEXAS INSTRUMENTS ADS7142 ADC DRIVER
+M:     Jozsef Horvath <info@ministro.hu>
+S:     Maintained
+F:     Documentation/ABI/testing/sysfs-bus-iio-adc-ti-ads7142
+F:     Documentation/devicetree/bindings/iio/adc/ti,ads7142.yaml
+F:     drivers/iio/adc/ti-ads7142.c
+
 TEXAS INSTRUMENTS ASoC DRIVERS
 M:     Peter Ujfalusi <peter.ujfalusi@gmail.com>
 L:     alsa-devel@alsa-project.org (moderated for non-subscribers)
diff --git a/drivers/iio/adc/Kconfig b/drivers/iio/adc/Kconfig
index db0c8fb60515..6c34ede355e4 100644
--- a/drivers/iio/adc/Kconfig
+++ b/drivers/iio/adc/Kconfig
@@ -1111,6 +1111,19 @@ config TI_ADS1015
          This driver can also be built as a module. If so, the module will be
          called ti-ads1015.

+config TI_ADS7142
+       tristate "Texas Instruments ADS7142 ADC driver"
+       depends on I2C
+       select IIO_BUFFER
+       select IIO_TRIGGERED_BUFFER
+       help
+         This driver is for Texas Instruments ADS7142 Nanopower,
+          Dual-Channel, Programmable Sensor Monitor.
+         Say 'Y' here if you wish to use it.
+
+         To compile this driver as a module, choose M here: the
+         module will be called ti-ads7142.
+
 config TI_ADS7950
        tristate "Texas Instruments ADS7950 ADC driver"
        depends on SPI && GPIOLIB
diff --git a/drivers/iio/adc/Makefile b/drivers/iio/adc/Makefile
index f70d877c555a..486ca7f4037e 100644
--- a/drivers/iio/adc/Makefile
+++ b/drivers/iio/adc/Makefile
@@ -99,6 +99,7 @@ obj-$(CONFIG_TI_ADC108S102) += ti-adc108s102.o
 obj-$(CONFIG_TI_ADC128S052) += ti-adc128s052.o
 obj-$(CONFIG_TI_ADC161S626) += ti-adc161s626.o
 obj-$(CONFIG_TI_ADS1015) += ti-ads1015.o
+obj-$(CONFIG_TI_ADS7142) += ti-ads7142.o
 obj-$(CONFIG_TI_ADS7950) += ti-ads7950.o
 obj-$(CONFIG_TI_ADS8344) += ti-ads8344.o
 obj-$(CONFIG_TI_ADS8688) += ti-ads8688.o
diff --git a/drivers/iio/adc/ti-ads7142.c b/drivers/iio/adc/ti-ads7142.c
new file mode 100644
index 000000000000..ab49531933e1
--- /dev/null
+++ b/drivers/iio/adc/ti-ads7142.c
@@ -0,0 +1,1469 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2021 Jozsef Horvath <info@ministro.hu>
+ *
+ */
+#include <linux/i2c.h>
+#include <linux/device.h>
+#include <linux/interrupt.h>
+#include <linux/err.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/regulator/consumer.h>
+#include <linux/iio/iio.h>
+#include <linux/iio/events.h>
+#include <linux/iio/buffer.h>
+#include <linux/iio/trigger_consumer.h>
+#include <linux/iio/triggered_buffer.h>
+
+#define TI_ADS7142_NAME                                        "ads7142"
+
+#define TI_ADS7142_DATA_VALID_TIMEOUT                  100
+
+/* Opcodes for commands */
+/* General */
+#define TI_ADS7142_OC_GENERAL                          0x00
+/* Single Register Read */
+#define TI_ADS7142_OC_SINGLE_REG_READ                  0x10
+/* Single Register Write */
+#define TI_ADS7142_OC_SINGLE_REG_WRITE                 0x08
+/* Single Bit Set */
+#define TI_ADS7142_OC_SET_BIT                          0x18
+/* Single Bit Clear */
+#define TI_ADS7142_OC_CLEAR_BIT                                0x20
+/* Block Register Read */
+#define TI_ADS7142_OC_BLOCK_READ                       0x30
+/* Block Register Write */
+#define TI_ADS7142_OC_BLOCK_WRITE                      0x28
+
+/* Registers */
+/* Reset registers */
+#define TI_ADS7142_WKEY                                        0x17
+#define TI_ADS7142_DEVICE_RESET                                0x14
+/* Functional mode select registers */
+#define TI_ADS7142_OFFSET_CAL                          0x15
+#define TI_ADS7142_OPMODE_SEL                          0x1C
+#define TI_ADS7142_OPMODE_SEL_MANUALCH0                        (0)
+#define TI_ADS7142_OPMODE_SEL_MANUALSEQ                        (4)
+#define TI_ADS7142_OPMODE_SEL_MONITORING               (6)
+#define TI_ADS7142_OPMODE_SEL_HIGHPREC                 (7)
+#define TI_ADS7142_OPMODE_STATUS                       0x00
+#define TI_ADS7142_OPMODE_STATUS_OPMODE_MSK            (3)
+#define TI_ADS7142_OPMODE_STATUS_OPMODE_MANUAL         (0)
+#define TI_ADS7142_OPMODE_STATUS_OPMODE_AUTO           (2)
+#define TI_ADS7142_OPMODE_STATUS_OPMODE_HIGHPREC       (3)
+#define TI_ADS7142_OPMODE_STATUS_HS_MODE               BIT(2)
+
+/* Input config register */
+#define TI_ADS7142_CH_INPUT_CFG                                0x24
+#define TI_ADS7142_CH_INPUT_CFG_TCSE                   (0)
+#define TI_ADS7142_CH_INPUT_CFG_SCSE                   (1)
+#define TI_ADS7142_CH_INPUT_CFG_SCPD                   (2)
+/* Analog mux and sequencer registers */
+#define TI_ADS7142_AUTO_SEQ_CHEN                       0x20
+#define TI_ADS7142_AUTO_SEQ_CHEN_CH0                   BIT(0)
+#define TI_ADS7142_AUTO_SEQ_CHEN_CH1                   BIT(1)
+#define TI_ADS7142_START_SEQUENCE                      0x1E
+#define TI_ADS7142_START_SEQUENCE_SEQ_START            BIT(0)
+#define TI_ADS7142_ABORT_SEQUENCE                      0x1F
+#define TI_ADS7142_ABORT_SEQUENCE_SEQ_ABORT            BIT(0)
+#define TI_ADS7142_SEQUENCE_STATUS                     0x04
+#define TI_ADS7142_SEQUENCE_STATUS_SEQ_ERR_ST_MSK      (0x06)
+#define TI_ADS7142_SEQUENCE_STATUS_SEQ_DISABLED                (0x00)
+#define TI_ADS7142_SEQUENCE_STATUS_SEQ_ENABLED         (0x02)
+#define TI_ADS7142_SEQUENCE_STATUS_SEQ_ERROR           (0x06)
+/* Oscillator and timing control registers */
+#define TI_ADS7142_OSC_SEL                             0x18
+#define TI_ADS7142_OSC_SEL_HSZ_LP                      BIT(0)
+#define TI_ADS7142_NCLK_SEL                            0x19
+#define TI_ADS7142_NCLK_SEL_MSK                                0xFF
+/* Data buffer control register */
+#define TI_ADS7142_DATA_BUFFER_OPMODE                  0x2C
+#define TI_ADS7142_DATA_BUFFER_OPMODE_STOP_BURST       (0)
+#define TI_ADS7142_DATA_BUFFER_OPMODE_START_BURST      (1)
+#define TI_ADS7142_DATA_BUFFER_OPMODE_PRE_ALERT                (4)
+#define TI_ADS7142_DATA_BUFFER_OPMODE_POST_ALERT       (6)
+#define TI_ADS7142_DOUT_FORMAT_CFG                     0x28
+#define TI_ADS7142_DOUT_FORMAT_CFG_12B                 (0)
+#define TI_ADS7142_DOUT_FORMAT_CFG_12BCH               (1)
+#define TI_ADS7142_DOUT_FORMAT_CFG_12BCHDV             (2)
+#define TI_ADS7142_DATA_BUFFER_STATUS                  0x01
+/* Accumulator control register */
+#define TI_ADS7142_ACC_EN                              0x30
+#define TI_ADS7142_ACC_CH0_LSB                         0x08
+#define TI_ADS7142_ACC_CH0_MSB                         0x09
+#define TI_ADS7142_ACC_CH1_LSB                         0x0A
+#define TI_ADS7142_ACC_CH1_MSB                         0x0B
+#define TI_ADS7142_ACC_STATUS                          0x02
+/* Digital window comparator registers */
+#define TI_ADS7142_ALERT_DWC_EN                                0x37
+#define TI_ADS7142_ALERT_DWC_EN_BLOCK_EN               BIT(0)
+#define TI_ADS7142_ALERT_CHEN                          0x34
+#define TI_ADS7142_DWC_HTH_CH0_LSB                     0x38
+#define TI_ADS7142_DWC_HTH_CH0_MSB                     0x39
+#define TI_ADS7142_DWC_LTH_CH0_LSB                     0x3A
+#define TI_ADS7142_DWC_LTH_CH0_MSB                     0x3B
+#define TI_ADS7142_DWC_HYS_CH0                         0x40
+#define TI_ADS7142_DWC_HTH_CH1_LSB                     0x3C
+#define TI_ADS7142_DWC_HTH_CH1_MSB                     0x3D
+#define TI_ADS7142_DWC_LTH_CH1_LSB                     0x3E
+#define TI_ADS7142_DWC_LTH_CH1_MSB                     0x3F
+#define TI_ADS7142_DWC_HYS_CH1                         0x41
+#define TI_ADS7142_PRE_ALT_EVT_CNT                     0x36
+#define TI_ADS7142_ALT_TRIG_CHID                       0x03
+#define TI_ADS7142_ALT_LOW_FLAGS                       0x0C
+#define TI_ADS7142_ALT_LOW_FLAGS_CH0                   BIT(0)
+#define TI_ADS7142_ALT_LOW_FLAGS_CH1                   BIT(1)
+#define TI_ADS7142_ALT_HIGH_FLAGS                      0x0E
+#define TI_ADS7142_ALT_HIGH_FLAGS_CH0                  BIT(0)
+#define TI_ADS7142_ALT_HIGH_FLAGS_CH1                  BIT(1)
+
+#define TI_ADS7142_THRESHOLD_MSK                       0xFFF
+#define TI_ADS7142_HYSTERESIS_MSK                      0x3F
+
+#define TI_ADS7142_HSO_FREQ                            20000000
+#define TI_ADS7142_HSO_NCLK_MIN                                21
+#define TI_ADS7142_HSO_NCLK_MAX                                255
+#define TI_ADS7142_HSO_MIN_SS                          78431
+#define TI_ADS7142_HSO_MAX_SS                          952380
+#define TI_ADS7142_LPO_FREQ                            10504
+#define TI_ADS7142_LPO_NCLK_MIN                                18
+#define TI_ADS7142_LPO_NCLK_MAX                                255
+#define TI_ADS7142_LPO_MIN_SS                          41
+#define TI_ADS7142_LPO_MAX_SS                          583
+
+#define TI_ADS7142_CHANNEL_COUNT                       2
+
+struct ti_ads7142_channel_config {
+       bool alert_low;
+       bool alert_high;
+       int high_threshold;
+       int low_threshold;
+       int hysteresis;
+};
+
+struct ti_ads7142_channel {
+       struct ti_ads7142_channel_config config;
+       u32 channel;
+};
+
+struct ti_ads7142_config {
+       bool osc_sel;
+       u32 n_clk;
+       int buffer_mode;
+};
+
+struct ti_ads7142_priv {
+       struct mutex lock; /* For syncing access to device */
+       struct regulator *avdd;
+       struct regulator *dvdd;
+       struct ti_ads7142_config config;
+       struct ti_ads7142_channel *channels;
+       u16 *scan_data;
+       bool irq_present;
+       bool monitor_pending;
+};
+
+static const struct iio_event_spec ti_ads7142_events[] = {
+       {
+               .type = IIO_EV_TYPE_THRESH,
+               .dir = IIO_EV_DIR_RISING,
+               .mask_separate = BIT(IIO_EV_INFO_VALUE)
+                               | BIT(IIO_EV_INFO_ENABLE),
+       }, {
+               .type = IIO_EV_TYPE_THRESH,
+               .dir = IIO_EV_DIR_FALLING,
+               .mask_separate = BIT(IIO_EV_INFO_VALUE)
+                               | BIT(IIO_EV_INFO_ENABLE),
+       }, {
+               .type = IIO_EV_TYPE_THRESH,
+               .dir = IIO_EV_DIR_EITHER,
+               .mask_separate = BIT(IIO_EV_INFO_HYSTERESIS),
+       },
+};
+
+static const char * const ti_ads7142_ain_names[] = {
+       "AIN0",
+       "AIN1",
+};
+
+#define TI_ADS7142_BUFFM_NONE                          0
+#define TI_ADS7142_BUFFM_STOP_BURST                    1
+#define TI_ADS7142_BUFFM_START_BURST                   2
+#define TI_ADS7142_BUFFM_PRE_ALERT                     3
+#define TI_ADS7142_BUFFM_POST_ALERT                    4
+static const char * const ti_ads7142_buffer_modes[] = {
+       [TI_ADS7142_BUFFM_NONE]         = "none",
+       [TI_ADS7142_BUFFM_STOP_BURST]   = "stop_burst",
+       [TI_ADS7142_BUFFM_START_BURST]  = "start_burst",
+       [TI_ADS7142_BUFFM_PRE_ALERT]    = "pre_alert",
+       [TI_ADS7142_BUFFM_POST_ALERT]   = "post_alert"
+};
+
+static int ti_ads7142_reg_write(const struct i2c_client *client, u8 reg,
+                               u8 data)
+{
+       u8 buf[3] = { TI_ADS7142_OC_SINGLE_REG_WRITE, reg, data };
+       int ret;
+
+       ret = i2c_master_send(client, buf, sizeof(buf));
+       if (ret >= 0 && ret != sizeof(buf))
+               ret = -EIO;
+
+       return ret == sizeof(buf) ? 0 : ret;
+}
+
+static int ti_ads7142_reg_read(const struct i2c_client *client, u8 reg,
+                              u8 *data)
+{
+       u8 buf[2] = { TI_ADS7142_OC_SINGLE_REG_READ, reg };
+       struct i2c_msg msg[2] = {
+               {
+                       .addr = client->addr,
+                       .len = sizeof(buf),
+                       .buf = buf,
+               },
+               {
+                       .addr = client->addr,
+                       .flags = I2C_M_RD,
+                       .len = 1,
+                       .buf = data,
+               }
+       };
+       int ret;
+
+       ret = i2c_transfer(client->adapter, msg, 2);
+       if (ret >= 0 && ret != ARRAY_SIZE(msg))
+               ret = -EIO;
+
+       return ret == ARRAY_SIZE(msg) ? 0 : ret;
+}
+
+static int ti_ads7142_data_buffer_read(const struct i2c_client *client,
+                                      int length, void *data)
+{
+       int ret;
+
+       ret = i2c_master_recv(client, data, length);
+       if (ret >= 0 && ret != length)
+               ret = -EIO;
+
+       return ret == length ? 0 : ret;
+}
+
+static int ti_ads7142_soft_reset(const struct i2c_client *client)
+{
+       u8 buf[2] = { TI_ADS7142_OC_GENERAL, 0x06 };
+       int ret;
+
+       ret = i2c_master_send(client, buf, sizeof(buf));
+       if (ret >= 0 && ret != sizeof(buf))
+               ret = -EIO;
+
+       return ret == sizeof(buf) ? 0 : ret;
+}
+
+static int ti_ads7142_address2channel(struct iio_dev *indio_dev,
+                                     int address,
+                                     struct ti_ads7142_channel **channel)
This could be simplified a bit to return "const struct
ti_ads7142_channel *" and then when NULL is returned, the caller
assumes -ENODEV.
Though, in  ti_ads7142_ist()  care should be taken to assign  ret =
-ENODEV; but that's only one place.

+{
+       struct ti_ads7142_priv *priv = iio_priv(indio_dev);
+       int i;
+
+       for (i = 0; i < indio_dev->num_channels; i++) {
+               if (address == priv->channels[i].channel) {
+                       *channel = &priv->channels[i];
+                       return 0;
+               }
+       }
+       return -ENODEV;
+}
+
+static int ti_ads7142_sequence_start(struct iio_dev *indio_dev)
+{
+       struct i2c_client *client = to_i2c_client(indio_dev->dev.parent);
+
+       return ti_ads7142_reg_write(client, TI_ADS7142_START_SEQUENCE,
+                                   TI_ADS7142_START_SEQUENCE_SEQ_START);
+}
+
+static int ti_ads7142_sequence_abort(struct iio_dev *indio_dev)
+{
+       struct i2c_client *client = to_i2c_client(indio_dev->dev.parent);
+
+       return ti_ads7142_reg_write(client, TI_ADS7142_ABORT_SEQUENCE,
+                                   TI_ADS7142_ABORT_SEQUENCE_SEQ_ABORT);
+}
+
+static int ti_ads7142_osc_set(struct iio_dev *indio_dev)
+{
+       struct ti_ads7142_priv *priv = iio_priv(indio_dev);
+       struct i2c_client *client = to_i2c_client(indio_dev->dev.parent);
+       int ret;
+
+       ret = ti_ads7142_reg_write(client, TI_ADS7142_OSC_SEL,
+                                  priv->config.osc_sel ? TI_ADS7142_OSC_SEL_HSZ_LP : 0);
+       if (ret)
+               return ret;
+
+       return ti_ads7142_reg_write(client, TI_ADS7142_NCLK_SEL,
+                                   priv->config.n_clk);
+}
+
+static int ti_ads7142_input_cfg_set(struct iio_dev *indio_dev)
+{
+       struct i2c_client *client = to_i2c_client(indio_dev->dev.parent);
+
+       return ti_ads7142_reg_write(client, TI_ADS7142_CH_INPUT_CFG,
+                                   TI_ADS7142_CH_INPUT_CFG_TCSE);
+}
+
+static int ti_ads7142_dout_format_set(struct iio_dev *indio_dev)
+{
+       struct i2c_client *client = to_i2c_client(indio_dev->dev.parent);
+
+       return ti_ads7142_reg_write(client, TI_ADS7142_DOUT_FORMAT_CFG,
+                                   TI_ADS7142_DOUT_FORMAT_CFG_12BCHDV);
+}
+
+static int ti_ads7142_osc_calc_set(struct iio_dev *indio_dev, int request)
+{
+       struct ti_ads7142_priv *priv = iio_priv(indio_dev);
+       bool osc_sel;
+       u32 osc_freq;
+
+       if (request <= TI_ADS7142_LPO_MAX_SS) {
+               osc_sel = true;
+               if (request < TI_ADS7142_LPO_MIN_SS)
+                       request = TI_ADS7142_LPO_MIN_SS;
+               osc_freq = TI_ADS7142_LPO_FREQ;
+       } else {
+               osc_sel = false;
+               if (request < TI_ADS7142_HSO_MIN_SS)
+                       request = TI_ADS7142_HSO_MIN_SS;
+               if (request > TI_ADS7142_HSO_MAX_SS)
+                       request = TI_ADS7142_HSO_MAX_SS;
+               osc_freq = TI_ADS7142_HSO_FREQ;
+       }
+
+       priv->config.osc_sel = osc_sel;
+       priv->config.n_clk = (osc_freq / request) & TI_ADS7142_NCLK_SEL_MSK;
+       return 0;
+}
+
+static int ti_ads7142_osc_calc_get(struct iio_dev *indio_dev, int *result)
+{
+       struct ti_ads7142_priv *priv = iio_priv(indio_dev);
+       u32 n_clk;
+       u32 osc_freq;
+
+       if (priv->config.osc_sel) {
+               // Low power oscillator
+               n_clk = priv->config.n_clk;
+               if (n_clk < TI_ADS7142_LPO_NCLK_MIN)
+                       n_clk = TI_ADS7142_LPO_NCLK_MIN;
+               if (n_clk > TI_ADS7142_LPO_NCLK_MAX)
+                       n_clk = TI_ADS7142_LPO_NCLK_MAX;
+               osc_freq = TI_ADS7142_LPO_FREQ;
+       } else {
+               // High speed oscillator
+               n_clk = priv->config.n_clk;
+               if (n_clk < TI_ADS7142_HSO_NCLK_MIN)
+                       n_clk = TI_ADS7142_HSO_NCLK_MIN;
+               if (n_clk > TI_ADS7142_HSO_NCLK_MAX)
+                       n_clk = TI_ADS7142_HSO_NCLK_MAX;
+               osc_freq = TI_ADS7142_HSO_FREQ;
+       }
+       *result = osc_freq / n_clk;
+       return 0;
+}
+
+static int ti_ads7142_hth_set(struct iio_dev *indio_dev, int channel,
+                             int threshold)
+{
+       struct i2c_client *client = to_i2c_client(indio_dev->dev.parent);
+       int ret;
+
+       if (threshold < 0 || threshold > TI_ADS7142_THRESHOLD_MSK)
+               return -EINVAL;
+
+       ret = ti_ads7142_reg_write(client,
+                                  TI_ADS7142_DWC_HTH_CH0_LSB + channel * 4,
+                                  threshold & 0xFF);
+       if (ret)
+               return ret;
+
+       ret = ti_ads7142_reg_write(client,
+                                  TI_ADS7142_DWC_HTH_CH0_MSB + channel * 4,
+                                  (threshold >> 8) & 0xF);
+       return ret;
+}
+
+static int ti_ads7142_lth_set(struct iio_dev *indio_dev, int channel,
+                             int threshold)
+{
+       struct i2c_client *client = to_i2c_client(indio_dev->dev.parent);
+       int ret;
+
+       if (threshold < 0 || threshold > TI_ADS7142_THRESHOLD_MSK)
+               return -EINVAL;
+
+       ret = ti_ads7142_reg_write(client,
+                                  TI_ADS7142_DWC_LTH_CH0_LSB + channel * 4,
+                                  threshold & 0xFF);
+       if (ret)
+               return ret;
+
+       ret = ti_ads7142_reg_write(client,
+                                  TI_ADS7142_DWC_LTH_CH0_MSB + channel * 4,
+                                  (threshold >> 8) & 0xF);
+       return ret;
+}
+
+static int ti_ads7142_hys_set(struct iio_dev *indio_dev, int channel,
+                             int hysteresis)
+{
+       struct i2c_client *client = to_i2c_client(indio_dev->dev.parent);
+       int ret;
+
+       if (hysteresis < 0 || hysteresis > TI_ADS7142_HYSTERESIS_MSK)
+               return -EINVAL;
+
+       ret = ti_ads7142_reg_write(client, TI_ADS7142_DWC_HYS_CH0 + channel,
+                                  hysteresis & TI_ADS7142_HYSTERESIS_MSK);
+       return ret;
+}
+
+static int ti_ads7142_buffered_setup_and_start(struct iio_dev *indio_dev)
+{
+       struct ti_ads7142_priv *priv = iio_priv(indio_dev);
+       struct i2c_client *client = to_i2c_client(indio_dev->dev.parent);
+       struct ti_ads7142_channel *channel;
+       int i;
+       u8 alert_ch = 0;
+       u8 buffer_op_mode;
+       u8 seq_channels = 0;
+       int ret;
+
+       if (!priv->config.buffer_mode)
+               return 0;
+
+       priv->monitor_pending = false;
+
+       ret = ti_ads7142_sequence_abort(indio_dev);
+       if (ret)
+               return ret;
+
+       ret = ti_ads7142_osc_set(indio_dev);
+       if (ret)
+               return ret;
+
+       ret = ti_ads7142_input_cfg_set(indio_dev);
+       if (ret)
+               return ret;
+
+       ret = ti_ads7142_dout_format_set(indio_dev);
+       if (ret)
+               return ret;
+
+       switch (priv->config.buffer_mode) {
+       case TI_ADS7142_BUFFM_STOP_BURST:
+               buffer_op_mode = TI_ADS7142_DATA_BUFFER_OPMODE_STOP_BURST;
+       break;
+       case TI_ADS7142_BUFFM_START_BURST:
+               buffer_op_mode = TI_ADS7142_DATA_BUFFER_OPMODE_START_BURST;
+       break;
+       case TI_ADS7142_BUFFM_PRE_ALERT:
+               buffer_op_mode = TI_ADS7142_DATA_BUFFER_OPMODE_PRE_ALERT;
+       break;
the indentation of the break; statements is a bit odd;
IIRC, they usually go aligned with the case block;
though i could be wrong;
+       case TI_ADS7142_BUFFM_POST_ALERT:
+               buffer_op_mode = TI_ADS7142_DATA_BUFFER_OPMODE_POST_ALERT;
+       break;
+       default:
+               return -EINVAL;
+       break;
also an unreachable statement
+       }
+       ret = ti_ads7142_reg_write(client, TI_ADS7142_DATA_BUFFER_OPMODE,
+                                  buffer_op_mode);
+       if (ret)
+               return ret;
+
+       ret = ti_ads7142_reg_write(client, TI_ADS7142_OPMODE_SEL,
+                                  TI_ADS7142_OPMODE_SEL_MONITORING);
+       if (ret)
+               return ret;
+
+       for_each_set_bit(i, indio_dev->active_scan_mask,
+                        indio_dev->masklength) {
+               seq_channels |= 1 << i;
+       }
+
+       ret = ti_ads7142_reg_write(client, TI_ADS7142_AUTO_SEQ_CHEN,
+                                  seq_channels);
+       if (ret)
+               return ret;
+
+       if (priv->config.buffer_mode < TI_ADS7142_BUFFM_PRE_ALERT)
+               goto seq_start;
+
+       /*
+        * Pre and post alert settings
+        */
+       ret = ti_ads7142_reg_write(client, TI_ADS7142_PRE_ALT_EVT_CNT, 0);
+       if (ret)
+               return ret;
+
+       ret = ti_ads7142_reg_write(client, TI_ADS7142_ALT_LOW_FLAGS,
+                                  TI_ADS7142_ALT_LOW_FLAGS_CH0
+                                  | TI_ADS7142_ALT_LOW_FLAGS_CH1);
+       if (ret)
+               return ret;
+
+       ret = ti_ads7142_reg_write(client, TI_ADS7142_ALT_HIGH_FLAGS,
+                                  TI_ADS7142_ALT_HIGH_FLAGS_CH0
+                                  | TI_ADS7142_ALT_HIGH_FLAGS_CH1);
+       if (ret)
+               return ret;
+
+       for_each_set_bit(i, indio_dev->active_scan_mask,
+                        indio_dev->masklength) {
+               ret = ti_ads7142_address2channel(indio_dev, i,
+                                                &channel);
+               if (ret)
+                       return ret;
+
+               ret = ti_ads7142_hth_set(indio_dev, channel->channel,
+                                        channel->config.high_threshold);
+               if (ret)
+                       return ret;
+
+               ret = ti_ads7142_lth_set(indio_dev, channel->channel,
+                                        channel->config.low_threshold);
+               if (ret)
+                       return ret;
+
+               ret = ti_ads7142_hys_set(indio_dev, channel->channel,
+                                        channel->config.hysteresis);
+               if (ret)
+                       return ret;
+
+               if (channel->config.alert_low ||
+                   channel->config.alert_high) {
+                       alert_ch |= 1 << channel->channel;
+               }
+       }
+
+       ret = ti_ads7142_reg_write(client, TI_ADS7142_ALERT_DWC_EN,
+                                  alert_ch ? TI_ADS7142_ALERT_DWC_EN_BLOCK_EN : 0);
+       if (ret)
+               return ret;
+
+       ret = ti_ads7142_reg_write(client, TI_ADS7142_ALERT_CHEN,
+                                  alert_ch);
+       if (ret)
+               return ret;
+
+       if (!alert_ch)
+               return ret;
this looks the same as
          if (!alert_ch)
              return 0;
for a while, this looked like 'ret' was not initialized;
+
+seq_start:
+       ret = ti_ads7142_sequence_start(indio_dev);
+       priv->monitor_pending = !ret;
+
+       return ret;
+}
+
+static int ti_ads7142_buffered_collect(struct iio_dev *indio_dev,
+                                      int *channel_collected)
+{
+       struct ti_ads7142_priv *priv = iio_priv(indio_dev);
+       struct i2c_client *client = to_i2c_client(indio_dev->dev.parent);
+       int scan_channel_count;
+       int have_valid_data;
+       int data_valid;
+       u16 data_buffer;
+       u16 buffer[TI_ADS7142_CHANNEL_COUNT];
+       u8 seq_channels = 0;
+       int channel_address;
+       int value;
+       int i, j;
+       int ret;
+
+       if (!priv->scan_data)
+               return -EINVAL;
+
+       scan_channel_count = bitmap_weight(indio_dev->active_scan_mask,
+                                          indio_dev->masklength);
+       if (!scan_channel_count)
+               return -EINVAL;
+
+       for_each_set_bit(i, indio_dev->active_scan_mask,
+                        indio_dev->masklength) {
+               seq_channels |= 1 << i;
+       }
+
+       do {
+               memset(priv->scan_data, 0x00, indio_dev->scan_bytes);
+               have_valid_data = 0;
+               for (i = 0; i < scan_channel_count; i++) {
+                       ret = ti_ads7142_data_buffer_read(client,
+                                                         sizeof(data_buffer),
+                                                         &data_buffer);
+                       if (ret)
+                               return ret;
+                       data_buffer = be16_to_cpu(data_buffer);
+                       data_valid = data_buffer & 1;
+                       if (!data_valid) {
+                               ret = -ENOENT;
+                               break;
+                       }
+
+                       channel_address = (data_buffer >> 1) & 0x7;
+                       if (!(seq_channels & 1 << channel_address)) {
+                               dev_err(indio_dev->dev.parent,
+                                       "%s: invalid channel address(%d)",
+                                       __func__, channel_address);
+                               return -EIO;
+                       }
+
+                       value = data_buffer >> 4;
+                       buffer[channel_address] = value;
+                       have_valid_data = 1;
+                       if (channel_collected)
+                               *channel_collected |= 1 << channel_address;
+               }
+
+               if (!have_valid_data)
+                       continue;
+
+               j = 0;
+               for_each_set_bit(i, indio_dev->active_scan_mask,
+                                indio_dev->masklength) {
+                       priv->scan_data[j] = buffer[i];
+                       j++;
+               }
+               iio_push_to_buffers_with_timestamp(indio_dev, priv->scan_data,
+                                                  iio_get_time_ns(indio_dev));
+       } while (data_valid);
+
+       return ret;
+}
+
+static int ti_ads7142_buffered_abort(struct iio_dev *indio_dev)
+{
+       struct ti_ads7142_priv *priv = iio_priv(indio_dev);
+       int ret;
+
+       ret = ti_ads7142_sequence_abort(indio_dev);
+       if (!ret)
+               priv->monitor_pending = false;
+
+       return ret;
+}
+
+static int ti_ads7142_manual_read(struct iio_dev *indio_dev,
+                                 int address, int *val)
+{
+       struct ti_ads7142_priv *priv = iio_priv(indio_dev);
+       struct i2c_client *client = to_i2c_client(indio_dev->dev.parent);
+       u16 data_buffer;
+       int ret;
+
+       mutex_lock(&priv->lock);
+       ret = ti_ads7142_sequence_abort(indio_dev);
+       if (ret)
+               goto final;
+
+       ret = ti_ads7142_osc_set(indio_dev);
+       if (ret)
+               goto final;
+
+       ret = ti_ads7142_input_cfg_set(indio_dev);
+       if (ret)
+               goto final;
+
+       ret = ti_ads7142_dout_format_set(indio_dev);
+       if (ret)
+               goto final;
+
+       ret = ti_ads7142_reg_write(client, TI_ADS7142_OPMODE_SEL,
+                                  TI_ADS7142_OPMODE_SEL_MANUALSEQ);
+       if (ret)
+               goto final;
+
+       ret = ti_ads7142_reg_write(client, TI_ADS7142_AUTO_SEQ_CHEN,
+                                  1 << address);
+       if (ret)
+               goto final;
+
+       ret = ti_ads7142_sequence_start(indio_dev);
+       if (ret)
+               goto final;
+
+       ret = ti_ads7142_data_buffer_read(client, sizeof(data_buffer),
+                                         &data_buffer);
+       if (ret)
+               goto abort;
+
+       *val = (be16_to_cpu(data_buffer) >> 4);
+
+abort:
+       ret = ti_ads7142_sequence_abort(indio_dev);
+final:
+       mutex_unlock(&priv->lock);
+       return ret;
+}
+
+static irqreturn_t ti_ads7142_ist(int irq, void *dev_id)
+{
+       struct iio_dev *indio_dev = dev_id;
+       struct i2c_client *client = to_i2c_client(indio_dev->dev.parent);
+       struct ti_ads7142_priv *priv = iio_priv(indio_dev);
+       struct ti_ads7142_channel *channel;
+       u8 low_flags;
+       u8 high_flags;
+       u8 seq_st;
+       int i;
+       int ret;
+       int channel_collected;
+       s64 timestamp = iio_get_time_ns(indio_dev);
+
+       mutex_lock(&priv->lock);
+       if (!priv->config.buffer_mode || !priv->monitor_pending) {
+               mutex_unlock(&priv->lock);
+               return IRQ_NONE;
+       }
+
+       /*
+        * BUSY/PDY fires when the sequence stopped in
+        * trigger handler(ti_ads7142_trigger_handler),
+        * if buffer mode is stop_burst, all the required
+        * operations are in trigger handler, so irq handler
+        * simple returns at this point.
+        */
+       if (priv->config.buffer_mode == TI_ADS7142_BUFFM_STOP_BURST) {
+               mutex_unlock(&priv->lock);
+               return IRQ_NONE;
+       }
+
+       ret = ti_ads7142_reg_read(client, TI_ADS7142_SEQUENCE_STATUS, &seq_st);
+       if (ret) {
+               dev_err(indio_dev->dev.parent,
+                       "%s: SEQUENCE_STATUS reg read error(%i)",
+                       __func__, ret);
+               goto final;
+       }
+
+       if ((seq_st & TI_ADS7142_SEQUENCE_STATUS_SEQ_ERR_ST_MSK)
+           != TI_ADS7142_SEQUENCE_STATUS_SEQ_ENABLED) {
+               dev_err(indio_dev->dev.parent,
+                       "%s: SEQUENCE_STATUS error(%i)",
+                       __func__, seq_st);
+               goto final;
+       }
+
+       ret = ti_ads7142_reg_read(client, TI_ADS7142_ALT_LOW_FLAGS,
+                                 &low_flags);
+       if (ret) {
+               dev_err(indio_dev->dev.parent,
+                       "%s: ALT_LOW_FLAGS reg read error(%i)",
+                       __func__, ret);
+               goto final;
+       }
+
+       ret = ti_ads7142_reg_read(client, TI_ADS7142_ALT_HIGH_FLAGS,
+                                 &high_flags);
+       if (ret) {
+               dev_err(indio_dev->dev.parent,
+                       "%s: ALT_HIGH_FLAGS reg read error(%i)",
+                       __func__, ret);
+               goto final;
+       }
+
+       ret = ti_ads7142_sequence_abort(indio_dev);
+       if (ret)
+               goto final;
+
+       priv->monitor_pending = false;
+
+       channel_collected = 0;
+       ret = ti_ads7142_buffered_collect(indio_dev, &channel_collected);
+       if (ret && ret != -ENOENT) {
+               dev_err(indio_dev->dev.parent,
+                       "%s: error(%d) when collecting result for %s mode",
+                       __func__, ret,
+                       ti_ads7142_buffer_modes[priv->config.buffer_mode]);
+               goto final;
+       }
+
+       if (ret == -ENOENT)
+               ret = 0;
+
+       if (!channel_collected)
+               goto final;
+
+       if (priv->config.buffer_mode < TI_ADS7142_BUFFM_PRE_ALERT)
+               goto final;
+
+       for_each_set_bit(i, indio_dev->active_scan_mask,
+                        indio_dev->masklength) {
+               ret = ti_ads7142_address2channel(indio_dev, i,
+                                                &channel);
+               if (ret)
+                       goto final;
+
+               if (!(channel_collected & (1 << channel->channel)))
+                       continue;
+               if (channel->config.alert_low &&
+                   (low_flags & (1 << channel->channel))) {
+                       iio_push_event(indio_dev,
+                                      IIO_UNMOD_EVENT_CODE(IIO_VOLTAGE,
+                                                           i,
+                                                           IIO_EV_TYPE_THRESH,
+                                                           IIO_EV_DIR_FALLING),
+                                      timestamp);
+               }
+
+               if (channel->config.alert_high &&
+                   (high_flags & (1 << channel->channel))) {
+                       iio_push_event(indio_dev,
+                                      IIO_UNMOD_EVENT_CODE(IIO_VOLTAGE,
+                                                           i,
+                                                           IIO_EV_TYPE_THRESH,
+                                                           IIO_EV_DIR_RISING),
+                                      timestamp);
+               }
+       }
+
+final:
This final label looks a bit busy.
Maybe an idea would be to have 2 labels, and depdending on 'ret' you
do "goto {err,out}_unlock":

out_unlock:
      if (priv->config.buffer_mode >= TI_ADS7142_BUFFM_PRE_ALERT) {
              ret = ti_ads7142_buffered_setup_and_start(indio_dev);
               if (ret) {
                      dev_err(indio_dev->dev.parent,
                              "%s: error(%d) when starting %s mode",
                              __func__, ret,

ti_ads7142_buffer_modes[priv->config.buffer_mode]);
                      goto err_unlock;
              }
      }
      mutex_unlock(&priv->lock);
      return IRQ_HANDLED;

err_unlock:
       mutex_unlock(&priv->lock);
       return IRQ_NONE;

+       if (!ret && priv->config.buffer_mode >= TI_ADS7142_BUFFM_PRE_ALERT) {
+               ret = ti_ads7142_buffered_setup_and_start(indio_dev);
+               if (ret) {
+                       dev_err(indio_dev->dev.parent,
+                               "%s: error(%d) when starting %s mode",
+                               __func__, ret,
+                               ti_ads7142_buffer_modes[priv->config.buffer_mode]);
+               }
+       }
+       mutex_unlock(&priv->lock);
+       if (ret)
+               return IRQ_NONE;
+
+       return IRQ_HANDLED;
+}
+
+static int ti_ads7142_read_raw(struct iio_dev *indio_dev,
+                              struct iio_chan_spec const *chan,
+                              int *val, int *val2, long info)
+{
+       struct ti_ads7142_priv *priv = iio_priv(indio_dev);
+       int ret;
+
+       switch (info) {
+       case IIO_CHAN_INFO_RAW:
+               if (iio_buffer_enabled(indio_dev))
+                       return -EBUSY;
+               ret = iio_device_claim_direct_mode(indio_dev);
+               if (ret)
+                       return ret;
+               ret = ti_ads7142_manual_read(indio_dev, chan->address,
+                                            val);
+               if (!ret)
+                       ret = IIO_VAL_INT;
+               iio_device_release_direct_mode(indio_dev);
+               return ret;
+       case IIO_CHAN_INFO_SAMP_FREQ:
+               ti_ads7142_osc_calc_get(indio_dev, val);
+               return IIO_VAL_INT;
+       case IIO_CHAN_INFO_SCALE:
+               if (IS_ERR(priv->avdd)) {
+                       ret = -EINVAL;
+               } else {
+                       *val = regulator_get_voltage(priv->avdd) / 1000;
+                       *val2 = chan->scan_type.realbits;
+                       ret = IIO_VAL_FRACTIONAL_LOG2;
+               }
purely stylistic change; but this could also be:

              if (IS_ERR(priv->avdd))
                  return -EINVAL

              *val = regulator_get_voltage(priv->avdd) / 1000;
              *val2 = chan->scan_type.realbits;
              return IIO_VAL_FRACTIONAL_LOG2;
+               return ret;
+       default:
+               return -EINVAL;
+       }
+       return 0;
This "return 0;" looks like an unreachable statement.
Some GCC versions complain about it. Not sure which.
+}
+
+static int ti_ads7142_write_raw(struct iio_dev *indio_dev,
+                               struct iio_chan_spec const *chan,
+                               int val, int val2, long mask)
+{
+       switch (mask) {
+       case IIO_CHAN_INFO_SAMP_FREQ:
+               return ti_ads7142_osc_calc_set(indio_dev, val);
+       default:
+               return -EINVAL;
+       }
+
+       return 0;
Also, an unreachale statement.
+}
+
+static int ti_ads7142_read_event_value(struct iio_dev *indio_dev,
+                                      const struct iio_chan_spec *chan,
+                                      enum iio_event_type type,
+                                      enum iio_event_direction dir,
+                                      enum iio_event_info info,
+                                      int *val, int *val2)
+{
+       struct ti_ads7142_channel *channel;
+       int ret;
+
+       ret = ti_ads7142_address2channel(indio_dev, chan->address,
+                                        &channel);
+       if (ret)
+               return ret;
+
+       switch (info) {
+       case IIO_EV_INFO_VALUE:
+               if (dir == IIO_EV_DIR_RISING)
+                       *val = channel->config.high_threshold;
+               else
+                       *val = channel->config.low_threshold;
+               return IIO_VAL_INT;
+       case IIO_EV_INFO_HYSTERESIS:
+               *val = channel->config.hysteresis;
+               return IIO_VAL_INT;
+       default:
+               return -EINVAL;
+       }
+       return 0;
Also an unreachable statement.
+}
+
+static int ti_ads7142_write_event_value(struct iio_dev *indio_dev,
+                                       const struct iio_chan_spec *chan,
+                                       enum iio_event_type type,
+                                       enum iio_event_direction dir,
+                                       enum iio_event_info info,
+                                       int val, int val2)
+{
+       struct ti_ads7142_channel *channel;
+       int ret;
+
+       ret = ti_ads7142_address2channel(indio_dev, chan->address,
+                                        &channel);
+       if (ret)
+               return ret;
+
+       switch (info) {
+       case IIO_EV_INFO_VALUE:
+               if (val < 0 || val > TI_ADS7142_THRESHOLD_MSK) {
+                       ret = -EINVAL;
+               } else {
+                       if (dir == IIO_EV_DIR_RISING)
+                               channel->config.high_threshold = val;
+                       else
+                               channel->config.low_threshold = val;
+               }
+       break;
+       case IIO_EV_INFO_HYSTERESIS:
+               if (val < 0 || val > TI_ADS7142_HYSTERESIS_MSK)
+                       ret = -EINVAL;
+               else
+                       channel->config.hysteresis = val;
+       break;
+       default:
+               ret = -EINVAL;
+       break;
+       }
+
+       return ret;
+}
+
+static int ti_ads7142_read_event_config(struct iio_dev *indio_dev,
+                                       const struct iio_chan_spec *chan,
+                                       enum iio_event_type type,
+                                       enum iio_event_direction dir)
+{
+       struct ti_ads7142_channel *channel;
+       int ret;
+
+       if (type != IIO_EV_TYPE_THRESH)
+               return -EINVAL;
+
+       ret = ti_ads7142_address2channel(indio_dev, chan->address,
+                                        &channel);
+       if (ret)
+               return ret;
+
+       if (dir == IIO_EV_DIR_RISING)
+               ret = channel->config.alert_high ? 1 : 0;
+       else
+               ret = channel->config.alert_low ? 1 : 0;
+
+       return ret;
+}
+
+static int ti_ads7142_write_event_config(struct iio_dev *indio_dev,
+                                        const struct iio_chan_spec *chan,
+                                        enum iio_event_type type,
+                                        enum iio_event_direction dir,
+                                        int state)
+{
+       struct ti_ads7142_channel *channel;
+       int ret;
+
+       if (type != IIO_EV_TYPE_THRESH)
+               return -EINVAL;
+
+       ret = ti_ads7142_address2channel(indio_dev, chan->address,
+                                        &channel);
+       if (ret)
+               return ret;
+
+       if (dir == IIO_EV_DIR_RISING)
+               channel->config.alert_high = state;
+       else
+               channel->config.alert_low = state;
+
+       return ret;
+}
+
+static const struct iio_info ti_ads7142_iio_info = {
+       .read_raw               = ti_ads7142_read_raw,
+       .write_raw              = ti_ads7142_write_raw,
+       .read_event_value       = ti_ads7142_read_event_value,
+       .write_event_value      = ti_ads7142_write_event_value,
+       .read_event_config      = ti_ads7142_read_event_config,
+       .write_event_config     = ti_ads7142_write_event_config,
+};
+
+static int ti_ads7142_triggered_buffer_preenable(struct iio_dev *indio_dev)
+{
+       struct ti_ads7142_priv *priv = iio_priv(indio_dev);
+       int ret;
+
+       if (!priv->config.buffer_mode)
+               return -EINVAL;
+
+       /*
+        * Start/stop burst buffer modes requires trigger
+        */
+       if (priv->config.buffer_mode <= TI_ADS7142_BUFFM_START_BURST &&
+           !indio_dev->trig) {
+               dev_err(indio_dev->dev.parent,
+                       "%s: Start/stop burst buffer modes requires trigger",
+                       __func__);
+               return -EINVAL;
+       }
+
+       /*
+        * Start burst and pre/post alert modes requires irq
+        */
+       if (priv->config.buffer_mode >= TI_ADS7142_BUFFM_START_BURST &&
+           !priv->irq_present) {
+               dev_err(indio_dev->dev.parent,
+                       "%s: Start burst and pre/post alert modes requires irq",
+                       __func__);
+               return -EINVAL;
+       }
+
+       priv->scan_data = devm_krealloc(indio_dev->dev.parent,
+                                       priv->scan_data,
+                                       indio_dev->scan_bytes, GFP_KERNEL);
the scan_data doesn't look like it would be awefully big;
so, it could be static buffer on 'priv';
it should be marked with ____cacheline_aligned  though  [if moved on
the priv object].
though, i don't feel too strongly about moving it;

+       if (!priv->scan_data)
+               return -ENOMEM;
+
+       mutex_lock(&priv->lock);
+       /*
+        * Start burst mode started in trigger handler.
+        * Sequencer aborted here, just for safe.
+        */
+       if (priv->config.buffer_mode == TI_ADS7142_BUFFM_START_BURST)
+               ret = ti_ads7142_buffered_abort(indio_dev);
+       else
+               ret = ti_ads7142_buffered_setup_and_start(indio_dev);
+       mutex_unlock(&priv->lock);
+
+       return ret;
+}
+
+static int ti_ads7142_triggered_buffer_predisable(struct iio_dev *indio_dev)
+{
+       struct ti_ads7142_priv *priv = iio_priv(indio_dev);
+       int ret = 0;
+
+       mutex_lock(&priv->lock);
+       ti_ads7142_buffered_abort(indio_dev);
+       mutex_unlock(&priv->lock);
+
+       return ret;
+}
+
+static const struct iio_buffer_setup_ops ti_ads7142_triggered_buffer_ops = {
+       .preenable = &ti_ads7142_triggered_buffer_preenable,
+       .predisable = &ti_ads7142_triggered_buffer_predisable,
+};
+
+static irqreturn_t ti_ads7142_trigger_handler(int irq, void *p)
+{
+       struct iio_poll_func *pf = p;
+       struct iio_dev *indio_dev = pf->indio_dev;
+       struct ti_ads7142_priv *priv = iio_priv(indio_dev);
+       int ret = 0;
+
+       mutex_lock(&priv->lock);
+       if (priv->config.buffer_mode == TI_ADS7142_BUFFM_STOP_BURST) {
+               ret = ti_ads7142_buffered_abort(indio_dev);
+               if (ret) {
+                       dev_err(indio_dev->dev.parent,
+                               "%s: error(%d) when aborting in %s mode",
+                               __func__, ret,
+                               ti_ads7142_buffer_modes[priv->config.buffer_mode]);
+               }
+
+               ret = ti_ads7142_buffered_collect(indio_dev, NULL);
+               if (ret && ret != -ENOENT) {
+                       dev_err(indio_dev->dev.parent,
+                               "%s: error(%d) when collecting result for %s mode",
+                               __func__, ret,
+                               ti_ads7142_buffer_modes[priv->config.buffer_mode]);
+               }
+
+               if (ret == -ENOENT)
+                       ret = 0;
+       }
+       if (!ret &&
+           (priv->config.buffer_mode == TI_ADS7142_BUFFM_START_BURST ||
+            priv->config.buffer_mode == TI_ADS7142_BUFFM_STOP_BURST)) {
+               ret = ti_ads7142_buffered_setup_and_start(indio_dev);
+               if (ret) {
+                       dev_err(indio_dev->dev.parent,
+                               "%s: error(%d) when starting %s mode",
+                               __func__, ret,
+                               ti_ads7142_buffer_modes[priv->config.buffer_mode]);
+               }
+       }
+
+       mutex_unlock(&priv->lock);
+
+       if (ret)
+               return IRQ_NONE;
maybe doing 2 labels here (with goto err_unlock/out_unlock) would be
an idea here as well;
+
+       iio_trigger_notify_done(indio_dev->trig);
+
+       return IRQ_HANDLED;
+}
+
+static int ti_ads7142_get_buffer_mode(struct iio_dev *indio_dev,
+                                     const struct iio_chan_spec *chan)
+{
+       struct ti_ads7142_priv *priv = iio_priv(indio_dev);
+
+       return priv->config.buffer_mode;
+}
+
+static int ti_ads7142_set_buffer_mode(struct iio_dev *indio_dev,
+                                     const struct iio_chan_spec *chan,
+                                     unsigned int mode)
+{
+       struct ti_ads7142_priv *priv = iio_priv(indio_dev);
+       int ret;
+
+       if (mode > TI_ADS7142_BUFFM_STOP_BURST && !priv->irq_present) {
+               dev_err(indio_dev->dev.parent,
+                       "%s: no irq(BUSY/RDY) specified, mode %s is not supported",
+                       __func__, ti_ads7142_buffer_modes[mode]);
+               return -EINVAL;
+       }
+
+       ret = iio_device_claim_direct_mode(indio_dev);
+       if (ret)
+               return ret;
+
+       priv->config.buffer_mode = mode;
+       iio_device_release_direct_mode(indio_dev);
+       return 0;
+}
+
+static const struct iio_enum ti_ads7142_buffer_modes_enum = {
+       .items = ti_ads7142_buffer_modes,
+       .num_items = ARRAY_SIZE(ti_ads7142_buffer_modes),
+       .get = ti_ads7142_get_buffer_mode,
+       .set = ti_ads7142_set_buffer_mode,
+};
+
+static const struct iio_chan_spec_ext_info ti_ads7142_ext_info[] = {
+       IIO_ENUM("buffer_mode", IIO_SHARED_BY_ALL,
+                &ti_ads7142_buffer_modes_enum),
+       {
+               .name = "buffer_mode_available",
+               .shared = IIO_SHARED_BY_ALL,
+               .read = iio_enum_available_read,
+               .private = (uintptr_t)&ti_ads7142_buffer_modes_enum,
+       },
+       { },
the comma can be removed here;
since it's a null terminator;
+};
+
+static int ti_ads7142_parse_channel_config(struct device *dev,
+                                          struct iio_dev *indio_dev)
+{
+       struct ti_ads7142_priv *priv = iio_priv(indio_dev);
+       struct fwnode_handle *channel_node;
+       struct iio_chan_spec *iio_channels;
+       struct iio_chan_spec *iio_channel;
+       struct ti_ads7142_channel *ads_channel;
+       int channel_index = 0;
+       int channel_count;
+       int ret;
+
+       channel_count = device_get_child_node_count(dev);
+       if (!channel_count) {
+               dev_err(dev, "dt: there is no channel definition");
+               return -ENODEV;
+       }
+
+       if (channel_count > TI_ADS7142_CHANNEL_COUNT) {
+               dev_err(dev, "dt: invalid number of channel definitions");
+               return -ENODEV;
+       }
+
+       priv->channels = devm_kcalloc(dev, channel_count,
+                                     sizeof(*priv->channels),
+                                     GFP_KERNEL);
+       if (!priv->channels)
+               return -ENOMEM;
It looks to me that this device has up-to 2 channels.
For such a low channel count, it may make sense to just keep a static
table of iio_channels pointers [1].
+
+       indio_dev->num_channels = channel_count;
+       iio_channels = devm_kcalloc(dev, channel_count, sizeof(*iio_channels),
+                                   GFP_KERNEL);
+       if (!iio_channels)
+               return -ENOMEM;
+
+       indio_dev->channels = iio_channels;
+
+       device_for_each_child_node(dev, channel_node) {
+               ads_channel = &priv->channels[channel_index];
+
+               ret = fwnode_property_read_u32(channel_node, "reg",
+                                              &ads_channel->channel);
+               if (ret) {
+                       fwnode_handle_put(channel_node);
+                       return ret;
+               }
+
+               iio_channel = &iio_channels[channel_index];
+               iio_channel->datasheet_name = ti_ads7142_ain_names[ads_channel->channel];
+               iio_channel->type = IIO_VOLTAGE;
+               iio_channel->indexed = 1;
+               iio_channel->info_mask_separate = BIT(IIO_CHAN_INFO_RAW);
+               if (!IS_ERR_OR_NULL(priv->avdd))
+                       iio_channel->info_mask_separate |= BIT(IIO_CHAN_INFO_SCALE);
+               iio_channel->info_mask_shared_by_all = BIT(IIO_CHAN_INFO_SAMP_FREQ);
+               iio_channel->scan_type.sign = 'u';
+               iio_channel->scan_type.realbits = 12;
+               iio_channel->scan_type.storagebits = 16;
+               iio_channel->scan_type.endianness = IIO_CPU;
+               iio_channel->address = ads_channel->channel;
+               iio_channel->scan_index = ads_channel->channel;
+               iio_channel->channel = ads_channel->channel;
+               iio_channel->event_spec = ti_ads7142_events;
+               iio_channel->num_event_specs = ARRAY_SIZE(ti_ads7142_events);
+               iio_channel->ext_info = ti_ads7142_ext_info;
+
+               ads_channel->config.high_threshold = TI_ADS7142_THRESHOLD_MSK;
+               channel_index++;
Also, here I think it may make sense to keep a global const-static
table of iio_channel object-parameters.
Then it can be assigned to the iio_channels [1] pointer-list and then
to indio_dev->channels/num_channels.
+       }
+
+       return 0;
+}
+
+static int ti_ads7142_parse_config(struct device *dev,
+                                  struct iio_dev *indio_dev)
+{
+       return ti_ads7142_parse_channel_config(dev, indio_dev);
+}
+
+static void ti_ads7142_regulators_disable(void *data)
+{
+       struct ti_ads7142_priv *priv = data;
+
+       if (!IS_ERR_OR_NULL(priv->avdd))
+               regulator_disable(priv->avdd);
+       if (!IS_ERR_OR_NULL(priv->dvdd))
+               regulator_disable(priv->dvdd);
+}
So, I've also learned this the hard way, but the general rule of these
callbacks is one per resource.
Something like:

static void ti_ads7142_regulators_disable(void *reg)
{
        regulator_disable(reg);
}

Then some calls are needed for each regulator.
Also, IS_ERR() can be used instead of IS_ERR_OR_NULL()
{devm_}regulator_get() always returns non-NULL.


        priv->avdd = devm_regulator_get(&client->dev, "avdd");
        if (!IS_ERR(priv->avdd)) {
                ret = regulator_enable(priv->avdd);
                if (ret)
                        return ret;

                ret = devm_add_action_or_reset(&client->dev,
                                               ti_ads7142_regulators_disable,
                                               priv->avdd);
                if (ret)
                        return ret;
        }

        priv->dvdd = devm_regulator_get(&client->dev, "dvdd");
        if (!IS_ERR(priv->dvdd)) {
                ret = regulator_enable(priv->dvdd);
                if (ret)
                        return ret;

                ret = devm_add_action_or_reset(&client->dev,
                                               ti_ads7142_regulators_disable,
                                               priv->dvdd);
                if (ret)
                        return ret;
        }

+
+static int ti_ads7142_probe(struct i2c_client *client,
+                           const struct i2c_device_id *id)
+{
+       struct iio_dev *indio_dev;
+       struct ti_ads7142_priv *priv;
+       int ret;
+
+       indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*priv));
+       if (!indio_dev)
+               return -ENOMEM;
+
+       i2c_set_clientdata(client, indio_dev);
+       priv = iio_priv(indio_dev);
+
+       /**
+        * starting from v5.9-rc1 iio_device_alloc
+        *  sets indio_dev->dev.parent, but older versions not :(
+        **/
+       if (!indio_dev->dev.parent)
+               indio_dev->dev.parent = &client->dev;
+       indio_dev->name = TI_ADS7142_NAME;
+       indio_dev->modes = INDIO_DIRECT_MODE | INDIO_BUFFER_SOFTWARE;
+       indio_dev->info = &ti_ads7142_iio_info;
+
+       priv->avdd = devm_regulator_get(&client->dev, "avdd");
+       if (!IS_ERR_OR_NULL(priv->avdd)) {
+               ret = regulator_enable(priv->avdd);
+               if (ret)
+                       return ret;
+       }
+
+       priv->dvdd = devm_regulator_get(&client->dev, "dvdd");
+       if (!IS_ERR_OR_NULL(priv->dvdd)) {
+               ret = regulator_enable(priv->dvdd);
+               if (ret)
+                       goto final;
+       }
+
+       ret = devm_add_action_or_reset(&client->dev,
+                                      ti_ads7142_regulators_disable,
+                                      priv);
+       if (ret)
+               goto final;
+
+       ret = ti_ads7142_soft_reset(client);
+       if (ret)
+               goto final;
+
+       ret = ti_ads7142_parse_config(&client->dev, indio_dev);
+       if (ret)
+               goto final;
+
+       mutex_init(&priv->lock);
+
+       if (client->irq) {
+               ret = devm_request_threaded_irq(&client->dev, client->irq,
+                                               NULL, ti_ads7142_ist,
+                                               IRQF_ONESHOT | IRQF_SHARED,
+                                               dev_name(&client->dev),
+                                               indio_dev);
+               if (ret) {
+                       dev_err(&client->dev, "Unable to request IRQ %i",
+                               client->irq);
+                       goto final;
+               }
+               priv->irq_present = true;
+       }
+
+       ret = devm_iio_triggered_buffer_setup(&client->dev,
+                                             indio_dev,
+                                             &iio_pollfunc_store_time,
+                                             &ti_ads7142_trigger_handler,
+                                             &ti_ads7142_triggered_buffer_ops);
+       if (ret)
+               goto final;
+
+       ret = devm_iio_device_register(&client->dev, indio_dev);
Usually "return devm_iio_device_register(&client->dev, indio_dev);" is
sufficient.
The rest is syslog spam.
+       if (ret) {
+               dev_err(&client->dev, "Failed to register iio device");
+               goto final;
+       }
+
+       dev_info(&client->dev, "%s is a %s device at address 0x%X",
+                dev_name(&indio_dev->dev), indio_dev->name,
+                client->addr);
+final:
This 'final' label looks odd.
It looks like all 'goto final' calls in this function could be
replaced with 'return ret'
And the return below could be 'return 0;'

+       return ret;
+}
+
+static int __maybe_unused ti_ads7142_suspend(struct device *dev)
+{
+       struct iio_dev *indio_dev = i2c_get_clientdata(to_i2c_client(dev));
+       struct ti_ads7142_priv *priv = iio_priv(indio_dev);
+
+       mutex_lock(&priv->lock);
+       do {
+               /*
+                * Keep all regulators on when the device in autonomous
+                *  monitoring mode.
+                * The device can wake up the system with ALERT pin
+                */
+               if (priv->monitor_pending &&
+                   (priv->config.buffer_mode == TI_ADS7142_BUFFM_PRE_ALERT ||
+                    priv->config.buffer_mode == TI_ADS7142_BUFFM_POST_ALERT))
+                       continue;
+
+               if (!IS_ERR_OR_NULL(priv->avdd))
+                       regulator_disable(priv->avdd);
+               if (!IS_ERR_OR_NULL(priv->dvdd))
+                       regulator_disable(priv->dvdd);
+       } while (0);
+       mutex_unlock(&priv->lock);
+
+       return 0;
+}
+
+static int __maybe_unused ti_ads7142_resume(struct device *dev)
+{
+       struct iio_dev *indio_dev = i2c_get_clientdata(to_i2c_client(dev));
+       struct ti_ads7142_priv *priv = iio_priv(indio_dev);
+       int ret = 0;
+
+       mutex_lock(&priv->lock);
+       do {
+               /*
+                * Nothing to do when the device in autonomous monitoring mode.
+                */
+               if (priv->monitor_pending &&
+                   (priv->config.buffer_mode == TI_ADS7142_BUFFM_PRE_ALERT ||
+                    priv->config.buffer_mode == TI_ADS7142_BUFFM_POST_ALERT))
+                       continue;
+
+               if (!IS_ERR_OR_NULL(priv->avdd)) {
+                       ret = regulator_enable(priv->avdd);
+                       if (ret)
+                               continue;
+               }
+               if (!IS_ERR_OR_NULL(priv->dvdd)) {
+                       ret = regulator_enable(priv->dvdd);
+                       if (ret)
+                               continue;
+               }
+       } while (0);
This while(0) loop looks a bit funky.
I understand why it's here; but it still looks a bit weird.
+       mutex_unlock(&priv->lock);
+
+       return ret;
+}
+
+static SIMPLE_DEV_PM_OPS(ti_ads7142_pm_ops, ti_ads7142_suspend,
+                        ti_ads7142_resume);
+
+static const struct i2c_device_id ti_ads7142_id[] = {
+       { TI_ADS7142_NAME, 0 },
+       { }
+};
+MODULE_DEVICE_TABLE(i2c, ti_ads7142_id);
+
+static const struct of_device_id ti_ads7142_of_match[] = {
+       { .compatible = "ti,ads7142" },
+       {}
+};
+MODULE_DEVICE_TABLE(of, ti_ads7142_of_match);
+
+static struct i2c_driver ti_ads7142_driver = {
+       .driver = {
+               .name = TI_ADS7142_NAME,
+               .of_match_table = ti_ads7142_of_match,
+               .pm = &ti_ads7142_pm_ops,
+       },
+       .probe          = ti_ads7142_probe,
+       .id_table       = ti_ads7142_id,
+};
+
+module_i2c_driver(ti_ads7142_driver);
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Jozsef Horvath [off-list ref]");
+MODULE_DESCRIPTION("Texas Instruments ADS7142 ADC driver");
--
2.17.1
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