Re: [PATCH 4/4] iio: accel: Add driver for the MiraMEMS DA280 3-axis 14-bit digital accelerometer

On 08/10/16 19:02, Hans de Goede wrote:

Hi,

On 08-10-16 19:17, Jonathan Cameron wrote:

quoted

On 08/10/16 13:34, Hans de Goede wrote:

quoted

Add an iio driver for the MiraMEMS DA280 3-axis 14-bit accelerometer, as
well as for the DA226 which is a fully compatible 2-axis version.

Datasheets for the DA280 and DA226 can be found at the manufacturers site:
http://www.miramems.com/en/products.asp?list=1

Signed-off-by: Hans de Goede <redacted>

How many more of these devices do you have? :)

I own 13 identical (on the outside) 7" android tablets with an
Allwinner A13/A23/A33 SoC, and I've access to 3 friends of mine own.

And I'm trying to run Fedora with the mainline kernel on all 16 of them.
I'm actually working on hardware auto-detection for devicetree to deal
with the internal differences these "identical" tablets have, see:

https://openiotelceurope2016.sched.org/event/7rqw/devicetree-hardware-autoconfiguration-hans-de-goede-red-hat?iframe=no&w=i:100;&sidebar=yes&bg=no

I've the accelerometer working on all of them (now), so this should
be my last patch for a while. Although I do plan to add orientation
support to all the accel drivers used in those tablets, so I
guess that will be another round of patches.

quoted

You have another unwanted le16_to_cpu conversion of data coming off
the back of an smbus word read.

Ugh, I distinctly remember thinking that I needed to take that
out in this driver too, but clearly I did not. I'll post a fixed
v2 soon.

Meh, happens to us all :)

quoted

Otherwise, looks good to me.

Thank you for the quick response and review. I must say I find
the iio subsys a very welcoming subsys to contribute too.

It is indeed a nice corner of the kernel to work in.  If it
wasn't I'd have burnt out long ago!

Stuff like Daniel and co + now Alison mentoring outreachy
certainly helps + a steady stream of other people just getting
started keeps a level of enthusiasm going.  Might help that generally
the parts are cheap and getting something going as you've seen
is simple + we are in the classic (advanced) maker territory.

Anyhow, I thoroughly agree and would just like to add thanks
to everyone who does review - I wouldn't keep up (anywhere near)
without you all!

Anyhow enough soppy stuff - back to reviewing ;)

Jonathan

Regards,

Hans

quoted

Jonathan

quoted

---
 .../devicetree/bindings/i2c/trivial-devices.txt    |   2 +
 drivers/iio/accel/Kconfig                          |  10 ++
 drivers/iio/accel/Makefile                         |   1 +
 drivers/iio/accel/da280.c                          | 183 +++++++++++++++++++++
 4 files changed, 196 insertions(+)
 create mode 100644 drivers/iio/accel/da280.c

diff --git a/Documentation/devicetree/bindings/i2c/trivial-devices.txt b/Documentation/devicetree/bindings/i2c/trivial-devices.txt
index b23ded3..6e4ba81 100644
--- a/Documentation/devicetree/bindings/i2c/trivial-devices.txt
+++ b/Documentation/devicetree/bindings/i2c/trivial-devices.txt

@@ -124,6 +124,8 @@ microchip,mcp4662-502    Microchip 8-bit Dual I2C Digital Potentiometer with NV Mem
 microchip,mcp4662-103    Microchip 8-bit Dual I2C Digital Potentiometer with NV Memory (10k)
 microchip,mcp4662-503    Microchip 8-bit Dual I2C Digital Potentiometer with NV Memory (50k)
 microchip,mcp4662-104    Microchip 8-bit Dual I2C Digital Potentiometer with NV Memory (100k)
+miramems,da226        MiraMEMS DA226 2-axis 14-bit digital accelerometer
+miramems,da280        MiraMEMS DA280 3-axis 14-bit digital accelerometer
 miramems,da311        MiraMEMS DA311 3-axis 12-bit digital accelerometer
 national,lm63        Temperature sensor with integrated fan control
 national,lm75        I2C TEMP SENSOR

diff --git a/drivers/iio/accel/Kconfig b/drivers/iio/accel/Kconfig
index c94348f..c2ed6cf 100644
--- a/drivers/iio/accel/Kconfig
+++ b/drivers/iio/accel/Kconfig

@@ -52,6 +52,16 @@ config BMC150_ACCEL_SPI
     tristate
     select REGMAP_SPI

+config DA280
+    tristate "MiraMEMS DA280 3-axis 14-bit digital accelerometer driver"
+    depends on I2C
+    help
+      Say yes here to build support for the MiraMEMS DA280 3-axis 14-bit
+      digital accelerometer.
+
+      To compile this driver as a module, choose M here: the
+      module will be called da280.
+
 config DA311
     tristate "MiraMEMS DA311 3-axis 12-bit digital accelerometer driver"
     depends on I2C

diff --git a/drivers/iio/accel/Makefile b/drivers/iio/accel/Makefile
index 601ca59..b7a9ba7 100644
--- a/drivers/iio/accel/Makefile
+++ b/drivers/iio/accel/Makefile

@@ -8,6 +8,7 @@ obj-$(CONFIG_BMA220) += bma220_spi.o
 obj-$(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-$(CONFIG_DA280)    += da280.o
 obj-$(CONFIG_DA311)    += da311.o
 obj-$(CONFIG_DMARD06)    += dmard06.o
 obj-$(CONFIG_DMARD09)    += dmard09.o

diff --git a/drivers/iio/accel/da280.c b/drivers/iio/accel/da280.c
new file mode 100644
index 0000000..7b1fe88
--- /dev/null
+++ b/drivers/iio/accel/da280.c

@@ -0,0 +1,183 @@
+/**
+ * IIO driver for the MiraMEMS DA280 3-axis accelerometer and
+ * IIO driver for the MiraMEMS DA226 2-axis accelerometer
+ *
+ * Copyright (c) 2016 Hans de Goede <hdegoede-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ */
+
+#include <linux/module.h>
+#include <linux/i2c.h>
+#include <linux/iio/iio.h>
+#include <linux/iio/sysfs.h>
+#include <linux/byteorder/generic.h>
+
+#define DA280_REG_CHIP_ID        0x01
+#define DA280_REG_ACC_X_LSB        0x02
+#define DA280_REG_ACC_Y_LSB        0x04
+#define DA280_REG_ACC_Z_LSB        0x06
+#define DA280_REG_MODE_BW        0x11
+
+#define DA280_CHIP_ID            0x13
+#define DA280_MODE_ENABLE        0x1e
+#define DA280_MODE_DISABLE        0x9e
+
+enum { da226, da280 };
+
+/*
+ * a value of + or -4096 corresponds to + or - 1G
+ * scale = 9.81 / 4096 = 0.002395019
+ */
+
+static const int da280_nscale = 2395019;
+
+#define DA280_CHANNEL(reg, axis) {    \
+    .type = IIO_ACCEL,    \
+    .address = reg,    \
+    .modified = 1,    \
+    .channel2 = IIO_MOD_##axis,    \
+    .info_mask_separate = BIT(IIO_CHAN_INFO_RAW),    \
+    .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),    \
+}
+
+static const struct iio_chan_spec da280_channels[] = {
+    DA280_CHANNEL(DA280_REG_ACC_X_LSB, X),
+    DA280_CHANNEL(DA280_REG_ACC_Y_LSB, Y),
+    DA280_CHANNEL(DA280_REG_ACC_Z_LSB, Z),
+};
+
+struct da280_data {
+    struct i2c_client *client;
+};
+
+static int da280_enable(struct i2c_client *client, bool enable)
+{
+    u8 data = enable ? DA280_MODE_ENABLE : DA280_MODE_DISABLE;
+
+    return i2c_smbus_write_byte_data(client, DA280_REG_MODE_BW, data);
+}
+
+static int da280_read_raw(struct iio_dev *indio_dev,
+                struct iio_chan_spec const *chan,
+                int *val, int *val2, long mask)
+{
+    struct da280_data *data = iio_priv(indio_dev);
+    int ret;
+
+    switch (mask) {
+    case IIO_CHAN_INFO_RAW:
+        ret = i2c_smbus_read_word_data(data->client, chan->address);
+        if (ret < 0)
+            return ret;
+        /*
+         * Values are 14 bits, stored as 16 bits with the 2
+         * least significant bits always 0.
+         */
+        *val = ((short)le16_to_cpu(ret)) >> 2;

Same thing Lars picked up on before I think...  It's already in cpu endian.

quoted

+        return IIO_VAL_INT;
+    case IIO_CHAN_INFO_SCALE:
+        *val = 0;
+        *val2 = da280_nscale;
+        return IIO_VAL_INT_PLUS_NANO;
+    default:
+        return -EINVAL;
+    }
+}
+
+static const struct iio_info da280_info = {
+    .driver_module    = THIS_MODULE,
+    .read_raw    = da280_read_raw,
+};
+
+static int da280_probe(struct i2c_client *client,
+            const struct i2c_device_id *id)
+{
+    int ret;
+    struct iio_dev *indio_dev;
+    struct da280_data *data;
+
+    ret = i2c_smbus_read_byte_data(client, DA280_REG_CHIP_ID);
+    if (ret != DA280_CHIP_ID)
+        return (ret < 0) ? ret : -ENODEV;
+
+    indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*data));
+    if (!indio_dev)
+        return -ENOMEM;
+
+    data = iio_priv(indio_dev);
+    data->client = client;
+    i2c_set_clientdata(client, indio_dev);
+
+    indio_dev->dev.parent = &client->dev;
+    indio_dev->info = &da280_info;
+    indio_dev->modes = INDIO_DIRECT_MODE;
+    indio_dev->channels = da280_channels;
+    if (id->driver_data == da226) {
+        indio_dev->name = "da226";
+        indio_dev->num_channels = 2;
+    } else {
+        indio_dev->name = "da280";
+        indio_dev->num_channels = 3;
+    }
+
+    ret = da280_enable(client, true);
+    if (ret < 0)
+        return ret;
+
+    ret = iio_device_register(indio_dev);
+    if (ret < 0) {
+        dev_err(&client->dev, "device_register failed\n");
+        da280_enable(client, false);
+    }
+
+    return ret;
+}
+
+static int da280_remove(struct i2c_client *client)
+{
+    struct iio_dev *indio_dev = i2c_get_clientdata(client);
+
+    iio_device_unregister(indio_dev);
+
+    return da280_enable(client, false);
+}
+
+#ifdef CONFIG_PM_SLEEP
+static int da280_suspend(struct device *dev)
+{
+    return da280_enable(to_i2c_client(dev), false);
+}
+
+static int da280_resume(struct device *dev)
+{
+    return da280_enable(to_i2c_client(dev), true);
+}
+#endif
+
+static SIMPLE_DEV_PM_OPS(da280_pm_ops, da280_suspend, da280_resume);
+
+static const struct i2c_device_id da280_i2c_id[] = {
+    { "da226", da226 },
+    { "da280", da280 },
+    {}
+};
+MODULE_DEVICE_TABLE(i2c, da280_i2c_id);
+
+static struct i2c_driver da280_driver = {
+    .driver = {
+        .name = "da280",
+        .pm = &da280_pm_ops,
+    },
+    .probe        = da280_probe,
+    .remove        = da280_remove,
+    .id_table    = da280_i2c_id,
+};
+
+module_i2c_driver(da280_driver);
+
+MODULE_AUTHOR("Hans de Goede [off-list ref]");
+MODULE_DESCRIPTION("MiraMEMS DA280 3-Axis Accelerometer driver");
+MODULE_LICENSE("GPL v2");

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