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Date: Sun, 1 May 2016 19:56:23 +0100
From: Jonathan Cameron <jic23@...nel.org>
To: Constantin Musca <constantin.musca@...el.com>, knaack.h@....de,
lars@...afoo.de, pmeerw@...erw.net, linux-kernel@...r.kernel.org,
linux-iio@...r.kernel.org
Cc: daniel.baluta@...el.com
Subject: Re: [PATCH v3] iio: accel: Add support for Freescale MMA7660FC
On 29/04/16 13:19, Constantin Musca wrote:
> Minimal implementation of an IIO driver for the Freescale
> MMA7660FC 3-axis accelerometer. Datasheet:
> http://www.freescale.com.cn/files/sensors/doc/data_sheet/MMA7660FC.pdf
>
> Includes:
> - ACPI support;
> - read_raw for x,y,z axes;
> - reading and setting the scale (range) parameter.
> - power management
>
> Signed-off-by: Constantin Musca <constantin.musca@...el.com>
Couple of trivial bits inline as well as that request to update the link above
if possible...
Why the retries? (I'm on a train without internet access for quite a few
hours yet hence I can't dig into the datasheet!)
Anyhow, even if it's obvious from the datasheet, that sort of 'magic' needs
an explanation comment...
Jonathan
> ---
> drivers/iio/accel/Kconfig | 10 ++
> drivers/iio/accel/Makefile | 2 +
> drivers/iio/accel/mma7660.c | 269 ++++++++++++++++++++++++++++++++++++++++++++
> 3 files changed, 281 insertions(+)
> create mode 100644 drivers/iio/accel/mma7660.c
>
> diff --git a/drivers/iio/accel/Kconfig b/drivers/iio/accel/Kconfig
> index e4a758c..1df6361 100644
> --- a/drivers/iio/accel/Kconfig
> +++ b/drivers/iio/accel/Kconfig
> @@ -136,6 +136,16 @@ config MMA7455_SPI
> To compile this driver as a module, choose M here: the module
> will be called mma7455_spi.
>
> +config MMA7660
> + tristate "Freescale MMA7660FC 3-Axis Accelerometer Driver"
> + depends on I2C
> + help
> + Say yes here to get support for the Freescale MMA7660FC 3-Axis
> + accelerometer.
> +
> + Choosing M will build the driver as a module. If so, the module
> + will be called mma7660.
> +
> config MMA8452
> tristate "Freescale MMA8452Q and similar Accelerometers Driver"
> depends on I2C
> diff --git a/drivers/iio/accel/Makefile b/drivers/iio/accel/Makefile
> index 71b6794..ba1165f 100644
> --- a/drivers/iio/accel/Makefile
> +++ b/drivers/iio/accel/Makefile
> @@ -15,6 +15,8 @@ obj-$(CONFIG_MMA7455) += mma7455_core.o
> obj-$(CONFIG_MMA7455_I2C) += mma7455_i2c.o
> obj-$(CONFIG_MMA7455_SPI) += mma7455_spi.o
>
> +obj-$(CONFIG_MMA7660) += mma7660.o
> +
> obj-$(CONFIG_MMA8452) += mma8452.o
>
> obj-$(CONFIG_MMA9551_CORE) += mma9551_core.o
> diff --git a/drivers/iio/accel/mma7660.c b/drivers/iio/accel/mma7660.c
> new file mode 100644
> index 0000000..94b2999
> --- /dev/null
> +++ b/drivers/iio/accel/mma7660.c
> @@ -0,0 +1,269 @@
> +/**
> + * Freescale MMA7660FC 3-Axis Accelerometer
> + *
> + * Copyright (c) 2016, Intel Corporation.
> + *
> + * This file is subject to the terms and conditions of version 2 of
> + * the GNU General Public License. See the file COPYING in the main
> + * directory of this archive for more details.
> + *
> + * IIO driver for Freescale MMA7660FC; 7-bit I2C address: 0x4c.
> + */
> +
> +#include <linux/acpi.h>
> +#include <linux/i2c.h>
> +#include <linux/module.h>
> +#include <linux/iio/iio.h>
> +#include <linux/iio/sysfs.h>
> +
> +#define MMA7660_DRIVER_NAME "mma7660"
> +
> +#define MMA7660_REG_XOUT 0x00
> +#define MMA7660_REG_YOUT 0x01
> +#define MMA7660_REG_ZOUT 0x02
> +#define MMA7660_REG_OUT_BIT_ALERT BIT(6)
> +
> +#define MMA7660_REG_MODE 0x07
> +#define MMA7660_REG_MODE_BIT_MODE BIT(0)
> +#define MMA7660_REG_MODE_BIT_TON BIT(2)
> +
> +#define MMA7660_I2C_READ_RETRIES 5
> +
> +/*
> + * The accelerometer has one measurement range:
> + *
> + * -1.5g - +1.5g (6-bit, signed)
> + *
> + * scale = (1.5 + 1.5) * 9.81 / (2^6 - 1) = 0.467142857
> + */
> +
> +#define MMA7660_SCALE_AVAIL "0.467142857"
> +
> +const int mma7660_nscale = 467142857;
> +
> +#define MMA7660_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 mma7660_channels[] = {
> + MMA7660_CHANNEL(MMA7660_REG_XOUT, X),
> + MMA7660_CHANNEL(MMA7660_REG_YOUT, Y),
> + MMA7660_CHANNEL(MMA7660_REG_ZOUT, Z),
> +};
> +
> +enum mma7660_mode {
> + MMA7660_MODE_STANDBY,
> + MMA7660_MODE_ACTIVE
> +};
> +
> +struct mma7660_data {
> + struct i2c_client *client;
> + struct mutex lock;
> + enum mma7660_mode mode;
> +};
> +
> +static IIO_CONST_ATTR(in_accel_scale_available, MMA7660_SCALE_AVAIL);
> +
> +static struct attribute *mma7660_attributes[] = {
> + &iio_const_attr_in_accel_scale_available.dev_attr.attr,
> + NULL,
> +};
> +
> +static const struct attribute_group mma7660_attribute_group = {
> + .attrs = mma7660_attributes
> +};
> +
> +static int mma7660_set_mode(struct mma7660_data *data,
> + enum mma7660_mode mode)
> +{
> + int ret;
> + struct i2c_client *client = data->client;
> +
> + if (mode == data->mode)
> + return 0;
> +
> + ret = i2c_smbus_read_byte_data(client, MMA7660_REG_MODE);
> + if (ret < 0) {
> + dev_err(&client->dev, "failed to read sensor mode\n");
> + return ret;
> + }
> +
> + if (mode == MMA7660_MODE_ACTIVE) {
> + ret &= ~MMA7660_REG_MODE_BIT_TON;
> + ret |= MMA7660_REG_MODE_BIT_MODE;
> + } else {
> + ret &= ~MMA7660_REG_MODE_BIT_TON;
> + ret &= ~MMA7660_REG_MODE_BIT_MODE;
> + }
> +
> + ret = i2c_smbus_write_byte_data(client, MMA7660_REG_MODE, ret);
> + if (ret < 0) {
> + dev_err(&client->dev, "failed to change sensor mode\n");
> + return ret;
> + }
> +
> + data->mode = mode;
blank line here (slightly prefered)...
> + return ret;
> +}
> +
> +static int mma7660_read_accel(struct mma7660_data *data, u8 address)
> +{
> + int ret, retries = MMA7660_I2C_READ_RETRIES;
> + struct i2c_client *client = data->client;
> +
This needs a comment to explain why a number of tries might be needed.
> + do {
> + ret = i2c_smbus_read_byte_data(client, address);
> + if (ret < 0) {
> + dev_err(&client->dev, "register read failed\n");
> + return ret;
> + }
> + } while (retries-- > 0 && ret & MMA7660_REG_OUT_BIT_ALERT);
> +
> + if (ret & MMA7660_REG_OUT_BIT_ALERT) {
> + dev_err(&client->dev, "all register read retries failed\n");
> + return -ETIMEDOUT;
> + }
> +
> + return ret;
> +}
> +
> +static int mma7660_read_raw(struct iio_dev *indio_dev,
> + struct iio_chan_spec const *chan,
> + int *val, int *val2, long mask)
> +{
> + struct mma7660_data *data = iio_priv(indio_dev);
> + int ret;
> +
> + switch (mask) {
> + case IIO_CHAN_INFO_RAW:
> + mutex_lock(&data->lock);
> + ret = mma7660_read_accel(data, chan->address);
> + mutex_unlock(&data->lock);
> + if (ret < 0)
> + return ret;
> + *val = sign_extend32(ret, 5);
> + return IIO_VAL_INT;
> + case IIO_CHAN_INFO_SCALE:
> + *val = 0;
> + *val2 = mma7660_nscale;
> + return IIO_VAL_INT_PLUS_NANO;
> + default:
> + return -EINVAL;
> + }
> +
> + return -EINVAL;
> +}
> +
> +static const struct iio_info mma7660_info = {
> + .driver_module = THIS_MODULE,
> + .read_raw = mma7660_read_raw,
> + .attrs = &mma7660_attribute_group,
> +};
> +
> +static int mma7660_probe(struct i2c_client *client,
> + const struct i2c_device_id *id)
> +{
> + int ret;
> + struct iio_dev *indio_dev;
> + struct mma7660_data *data;
> +
> + indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*data));
> + if (!indio_dev) {
> + dev_err(&client->dev, "iio allocation failed!\n");
> + return -ENOMEM;
> + }
> +
> + data = iio_priv(indio_dev);
> + data->client = client;
> + i2c_set_clientdata(client, indio_dev);
> + mutex_init(&data->lock);
> + data->mode = MMA7660_MODE_STANDBY;
> +
> + indio_dev->dev.parent = &client->dev;
> + indio_dev->info = &mma7660_info;
> + indio_dev->name = MMA7660_DRIVER_NAME;
> + indio_dev->modes = INDIO_DIRECT_MODE;
> + indio_dev->channels = mma7660_channels;
> + indio_dev->num_channels = ARRAY_SIZE(mma7660_channels);
> +
> + ret = mma7660_set_mode(data, MMA7660_MODE_ACTIVE);
> + if (ret < 0)
> + return ret;
> +
> + ret = iio_device_register(indio_dev);
> + if (ret < 0) {
> + dev_err(&client->dev, "device_register failed\n");
> + mma7660_set_mode(data, MMA7660_MODE_STANDBY);
> + }
> +
> + return ret;
> +}
> +
> +static int mma7660_remove(struct i2c_client *client)
> +{
> + struct iio_dev *indio_dev = i2c_get_clientdata(client);
> +
> + iio_device_unregister(indio_dev);
> +
> + return mma7660_set_mode(iio_priv(indio_dev), MMA7660_MODE_STANDBY);
> +}
> +
> +#ifdef CONFIG_PM_SLEEP
> +static int mma7660_suspend(struct device *dev)
> +{
> + struct mma7660_data *data;
> +
> + data = iio_priv(i2c_get_clientdata(to_i2c_client(dev)));
> +
> + return mma7660_set_mode(data, MMA7660_MODE_STANDBY);
> +}
> +
> +static int mma7660_resume(struct device *dev)
> +{
> + struct mma7660_data *data;
> +
> + data = iio_priv(i2c_get_clientdata(to_i2c_client(dev)));
> +
> + return mma7660_set_mode(data, MMA7660_MODE_ACTIVE);
> +}
> +
> +static SIMPLE_DEV_PM_OPS(mma7660_pm_ops, mma7660_suspend, mma7660_resume);
> +
> +#define MMA7660_PM_OPS (&mma7660_pm_ops)
> +#else
> +#define MMA7660_PM_OPS NULL
> +#endif
> +
> +static const struct i2c_device_id mma7660_i2c_id[] = {
> + {"mma7660", 0},
> + {}
> +};
> +
> +static const struct acpi_device_id mma7660_acpi_id[] = {
> + {"MMA7660", 0},
> + {}
> +};
> +
> +MODULE_DEVICE_TABLE(acpi, mma7660_acpi_id);
> +
> +static struct i2c_driver mma7660_driver = {
> + .driver = {
> + .name = "mma7660",
> + .pm = MMA7660_PM_OPS,
> + .acpi_match_table = ACPI_PTR(mma7660_acpi_id),
> + },
> + .probe = mma7660_probe,
> + .remove = mma7660_remove,
> + .id_table = mma7660_i2c_id,
> +};
> +
> +module_i2c_driver(mma7660_driver);
> +
> +MODULE_AUTHOR("Constantin Musca <constantin.musca@...el.com>");
> +MODULE_DESCRIPTION("Freescale MMA7660FC 3-Axis Accelerometer driver");
> +MODULE_LICENSE("GPL v2");
>
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