Comments inlined below.


Met vriendelijke groet / kind regards,

Mike Looijmans
System Expert


TOPIC Embedded Products B.V.
Materiaalweg 4, 5681 RJ Best
The Netherlands

T: +31 (0) 499 33 69 69
E: mike.looijmans@topicproducts.com
W: www.topicproducts.com

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On 20-01-2021 21:22, Jonathan Cameron wrote:

On Tue, 19 Jan 2021 13:46:22 +0100
Mike Looijmans [off-list ref] wrote:

quoted

The BMI088 is a combined module with both accelerometer and gyroscope.
This adds the accelerometer driver support for the SPI interface.
The gyroscope part is already supported by the BMG160 driver.

Signed-off-by: Mike Looijmans <redacted>
---

Changes in v6:
Hope you have good memory - v5 was almost a year ago now

*laughs* fresh review so probably disagree with what I said back then on
something :)


A few really small comments inline seeing as you are respinning anyway.

quoted

Remove superfluous *val=0
Make sample_frequency selection into read_avail list

Changes in v5:
Add includes and forward defines in header
BIT(7) instead of 0x80
Reset already sets defaults, do not set them again
Remove now unused bmi088_accel_set_bw
Remove unused AXIS_MAX
Use MASK define for ODR setting
Explain buffer use and alignment
Split bmi088_accel_set_power_state into "on" and "off" parts
Cosmetic changes to improve readability

Changes in v4:
Remove unused #include directives
Remove unused #defines for event and irq
Replace (ret < 0) with (ret) for all regmap calls
Consistent checking of IO errors in probe and init
Removed #ifdef CONFIG_PM guard
Use bitops for set_frequency instead of loop with shift
s/__s16/s16/g
Remove excess blank lines
Don't return -EAGAIN in pm_runtime

Changes in v3:
Processed comments from Jonathan Cameron and Lars-Peter Clausen
implement runtime PM (tested by code tracing) and sleep
fix scale and offset factors for accel and temperature and
return raw values instead of pre-scaled ones
Use iio_device_{claim,release}_direct_mode
Remove unused code and structs
Use a cache-aligned buffer for bulk read
Configure and enable caching register values

Changes in v2:
Remove unused typedefs and variables
Fix error return when iio_device_register fails

  drivers/iio/accel/Kconfig             |  18 +
  drivers/iio/accel/Makefile            |   2 +
  drivers/iio/accel/bmi088-accel-core.c | 630 ++++++++++++++++++++++++++
  drivers/iio/accel/bmi088-accel-spi.c  |  85 ++++
  drivers/iio/accel/bmi088-accel.h      |  18 +
  5 files changed, 753 insertions(+)
  create mode 100644 drivers/iio/accel/bmi088-accel-core.c
  create mode 100644 drivers/iio/accel/bmi088-accel-spi.c
  create mode 100644 drivers/iio/accel/bmi088-accel.h

diff --git a/drivers/iio/accel/Kconfig b/drivers/iio/accel/Kconfig
index 2e0c62c39155..cceda3cecbcf 100644
--- a/drivers/iio/accel/Kconfig
+++ b/drivers/iio/accel/Kconfig

@@ -157,6 +157,24 @@ config BMC150_ACCEL_SPI
  	tristate
  	select REGMAP_SPI
  
+config BMI088_ACCEL
+	tristate "Bosch BMI088 Accelerometer Driver"
+	depends on SPI
+	select IIO_BUFFER
+	select IIO_TRIGGERED_BUFFER
+	select REGMAP
+	select BMI088_ACCEL_SPI
+	help
+	  Say yes here to build support for the Bosch BMI088 accelerometer.
+
+	  This is a combo module with both accelerometer and gyroscope. This
+	  driver only implements the accelerometer part, which has its own
+	  address and register map. BMG160 provides the gyroscope driver.
+
+config BMI088_ACCEL_SPI
+	tristate
+	select REGMAP_SPI
+
  config DA280
  	tristate "MiraMEMS DA280 3-axis 14-bit digital accelerometer driver"
  	depends on I2C

diff --git a/drivers/iio/accel/Makefile b/drivers/iio/accel/Makefile
index 4f6c1ebe13b0..32cd1342a31a 100644
--- a/drivers/iio/accel/Makefile
+++ b/drivers/iio/accel/Makefile

@@ -20,6 +20,8 @@ obj-$(CONFIG_BMA400_SPI) += bma400_spi.o
  obj-$(CONFIG_BMC150_ACCEL) += bmc150-accel-core.o
  obj-$(CONFIG_BMC150_ACCEL_I2C) += bmc150-accel-i2c.o
  obj-$(CONFIG_BMC150_ACCEL_SPI) += bmc150-accel-spi.o
+obj-$(CONFIG_BMI088_ACCEL) += bmi088-accel-core.o
+obj-$(CONFIG_BMI088_ACCEL_SPI) += bmi088-accel-spi.o
  obj-$(CONFIG_DA280)	+= da280.o
  obj-$(CONFIG_DA311)	+= da311.o
  obj-$(CONFIG_DMARD06)	+= dmard06.o

diff --git a/drivers/iio/accel/bmi088-accel-core.c b/drivers/iio/accel/bmi088-accel-core.c
new file mode 100644
index 000000000000..788e54ed0728
--- /dev/null
+++ b/drivers/iio/accel/bmi088-accel-core.c

@@ -0,0 +1,630 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * 3-axis accelerometer driver supporting following Bosch-Sensortec chips:
+ *  - BMI088
+ *
+ * Copyright (c) 2018-2020, Topic Embedded Products
+ */
+
+#include <linux/module.h>
+#include <linux/interrupt.h>
+#include <linux/delay.h>

As below. Alphabetical ordering preferred.

Will do.

quoted

+#include <linux/slab.h>
+#include <linux/acpi.h>
+#include <linux/pm.h>
+#include <linux/pm_runtime.h>
+#include <linux/iio/iio.h>
+#include <linux/iio/sysfs.h>
+#include <linux/regmap.h>
+#include <asm/unaligned.h>
+
+#include "bmi088-accel.h"

...

quoted

+static int bmi088_accel_chip_init(struct bmi088_accel_data *data)
+{
+	struct device *dev = regmap_get_device(data->regmap);
+	int ret, i;
+	unsigned int val;
+
+	/* Do a dummy read to enable SPI interface, won't harm I2C */
+	regmap_read(data->regmap, BMI088_ACCEL_REG_INT_STATUS, &val);
+
+	/*
+	 * Reset chip to get it in a known good state. A delay of 1ms after
+	 * reset is required according to the data sheet
+	 */
+	ret = regmap_write(data->regmap, BMI088_ACCEL_REG_RESET,
+			   BMI088_ACCEL_RESET_VAL);
+	if (ret)
+		return ret;
+
+	usleep_range(1000, 2000);
+
+	/* Do a dummy read again after a reset to enable the SPI interface */
+	regmap_read(data->regmap, BMI088_ACCEL_REG_INT_STATUS, &val);
+
+	/* Read chip ID */
+	ret = regmap_read(data->regmap, BMI088_ACCEL_REG_CHIP_ID, &val);
+	if (ret) {
+		dev_err(dev, "Error: Reading chip id\n");
+		return ret;
+	}
+
+	/* Validate chip ID */
+	for (i = 0; i < ARRAY_SIZE(bmi088_accel_chip_info_tbl); i++) {
+		if (bmi088_accel_chip_info_tbl[i].chip_id == val) {
+			data->chip_info = &bmi088_accel_chip_info_tbl[i];
+			break;
+		}
+	}
+	if (i == ARRAY_SIZE(bmi088_accel_chip_info_tbl)) {
+		dev_err(dev, "Invalid chip %x\n", val);
+		return -ENODEV;
+	}
+
+	/* Enable accelerometer after reset */
+	return bmi088_accel_enable(data, true);

We bring the device up here, but I'm not seeing it turned off again
in either error paths of probe or remove.
Am I missing it somewhere?

Nah makes sense to put it back in the disabled state at removal.
I'll re-use the "suspend" code in the "remove" call so it'll be less code in 
total and things will be symetric.

quoted

+}
+
+int bmi088_accel_core_probe(struct device *dev, struct regmap *regmap,
+	int irq, const char *name, bool block_supported)
+{
+	struct bmi088_accel_data *data;
+	struct iio_dev *indio_dev;
+	int ret;
+
+	indio_dev = devm_iio_device_alloc(dev, sizeof(*data));
+	if (!indio_dev)
+		return -ENOMEM;
+
+	data = iio_priv(indio_dev);
+	dev_set_drvdata(dev, indio_dev);
+
+	data->regmap = regmap;
+
+	ret = bmi088_accel_chip_init(data);
+	if (ret)
+		return ret;
+
+	mutex_init(&data->mutex);
+
+	indio_dev->dev.parent = dev;
+	indio_dev->channels = data->chip_info->channels;
+	indio_dev->num_channels = data->chip_info->num_channels;
+	indio_dev->name = name ? name : data->chip_info->name;
+	indio_dev->available_scan_masks = bmi088_accel_scan_masks;
+	indio_dev->modes = INDIO_DIRECT_MODE;
+	indio_dev->info = &bmi088_accel_info;
+
+	ret = pm_runtime_set_active(dev);
+	if (ret)
+		return ret;
+
+	pm_runtime_enable(dev);
+	pm_runtime_set_autosuspend_delay(dev, BMI088_AUTO_SUSPEND_DELAY_MS);
+	pm_runtime_use_autosuspend(dev);
+
+	ret = iio_device_register(indio_dev);
+	if (ret)
+		dev_err(dev, "Unable to register iio device\n");
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(bmi088_accel_core_probe);
+
+int bmi088_accel_core_remove(struct device *dev)
+{
+	struct iio_dev *indio_dev = dev_get_drvdata(dev);
+	struct bmi088_accel_data *data = iio_priv(indio_dev);
+
+	iio_device_unregister(indio_dev);
+
+	pm_runtime_disable(dev);
+	pm_runtime_set_suspended(dev);
+	pm_runtime_put_noidle(dev);
+
+	mutex_lock(&data->mutex);
+	bmi088_accel_set_mode(data, BMI088_ACCEL_MODE_SUSPEND);
+	mutex_unlock(&data->mutex);
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(bmi088_accel_core_remove);
+
+/* When going into system sleep, put the chip in power down */
+static int __maybe_unused bmi088_accel_suspend(struct device *dev)
+{
+	struct iio_dev *indio_dev = dev_get_drvdata(dev);
+	struct bmi088_accel_data *data = iio_priv(indio_dev);
+
+	mutex_lock(&data->mutex);
+	bmi088_accel_set_mode(data, BMI088_ACCEL_MODE_SUSPEND);
+	bmi088_accel_enable(data, false);
+	mutex_unlock(&data->mutex);
+
+	return 0;
+}
+
+static int __maybe_unused bmi088_accel_resume(struct device *dev)
+{
+	struct iio_dev *indio_dev = dev_get_drvdata(dev);
+	struct bmi088_accel_data *data = iio_priv(indio_dev);
+
+	mutex_lock(&data->mutex);
+	bmi088_accel_enable(data, true);
+	bmi088_accel_set_mode(data, BMI088_ACCEL_MODE_ACTIVE);
+	mutex_unlock(&data->mutex);
+
+	return 0;
+}
+
+/* For runtime PM put the chip in suspend mode */
+static int __maybe_unused bmi088_accel_runtime_suspend(struct device *dev)
+{
+	struct iio_dev *indio_dev = dev_get_drvdata(dev);
+	struct bmi088_accel_data *data = iio_priv(indio_dev);
+
+	return bmi088_accel_set_mode(data, BMI088_ACCEL_MODE_SUSPEND);
+}
+
+static int __maybe_unused bmi088_accel_runtime_resume(struct device *dev)
+{
+	struct iio_dev *indio_dev = dev_get_drvdata(dev);
+	struct bmi088_accel_data *data = iio_priv(indio_dev);
+	int ret;
+
+	ret = bmi088_accel_set_mode(data, BMI088_ACCEL_MODE_ACTIVE);
+	if (ret)
+		return ret;
+
+	usleep_range(BMI088_ACCEL_MAX_STARTUP_TIME_US,
+		     BMI088_ACCEL_MAX_STARTUP_TIME_US * 2);
+
+	return 0;
+}
+
+const struct dev_pm_ops bmi088_accel_pm_ops = {
+	SET_SYSTEM_SLEEP_PM_OPS(bmi088_accel_suspend, bmi088_accel_resume)
+	SET_RUNTIME_PM_OPS(bmi088_accel_runtime_suspend,
+			   bmi088_accel_runtime_resume, NULL)
+};
+EXPORT_SYMBOL_GPL(bmi088_accel_pm_ops);
+
+MODULE_AUTHOR("Niek van Agt [off-list ref]");
+MODULE_LICENSE("GPL v2");
+MODULE_DESCRIPTION("BMI088 accelerometer driver (core)");

diff --git a/drivers/iio/accel/bmi088-accel-spi.c b/drivers/iio/accel/bmi088-accel-spi.c
new file mode 100644
index 000000000000..7794090b8e6d
--- /dev/null
+++ b/drivers/iio/accel/bmi088-accel-spi.c

@@ -0,0 +1,85 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * 3-axis accelerometer driver supporting following Bosch-Sensortec chips:
+ *  - BMI088
+ *
+ * Copyright (c) 2018-2020, Topic Embedded Products
+ */
+
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/spi/spi.h>
+#include <linux/regmap.h>

If no other reason for ordering ever so slight preference for
alphabetical order.

Will do

quoted

+
+#include "bmi088-accel.h"
+
+int bmi088_regmap_spi_write(void *context, const void *data, size_t count)

This should have been a static (as reported by build bot)

quoted

+{
+	struct spi_device *spi = context;
+
+	/* Write register is same as generic SPI */
+	return spi_write(spi, data, count);
+}
+
+int bmi088_regmap_spi_read(void *context, const void *reg,
+				size_t reg_size, void *val, size_t val_size)
+{
+	struct spi_device *spi = context;
+	u8 addr[2];
+
+	addr[0] = *(u8 *)reg;
+	addr[0] |= BIT(7); /* Set RW = '1' */
+	addr[1] = 0; /* Read requires a dummy byte transfer */
+
+	return spi_write_then_read(spi, addr, sizeof(addr), val, val_size);
+}
+
+static struct regmap_bus bmi088_regmap_bus = {
+	.write = bmi088_regmap_spi_write,
+	.read = bmi088_regmap_spi_read,
+	.reg_format_endian_default = REGMAP_ENDIAN_BIG,
+	.val_format_endian_default = REGMAP_ENDIAN_BIG,

Aren't these both 8 bits, making endian rather irrelevant?

Indeed, all registers are accessed as 8-bit only. Where bulk-read is involved, 
the byte order in interpreted in code.

quoted

+};

...