Re: [PATCH v2 1/3] iio: accel: add support for mxc4005 accelerometer

From: Jonathan Cameron
Date: Sun Aug 16 2015 - 03:32:32 EST

On 13/08/15 18:31, Teodora Baluta wrote:
> This patch adds support for Memsic MXC4005XC 3-axis accelerometer. The
> current implementation is a minimal one as it adds raw readings for the
> three axes and setting scale from userspace.
>
> Signed-off-by: Teodora Baluta <teodora.baluta@xxxxxxxxx>
Looking pretty good. Some real nitpicks and minor suggestions
inline. I was going to leave this on the list anyway to give
Peter and others time for another look so thought I might as
well be fussy. What can I say. It's Sunday morning and the
coffee hasn't kicked in yet :)

Jonathan
> ---
> drivers/iio/accel/Kconfig | 11 ++
> drivers/iio/accel/Makefile | 2 +
> drivers/iio/accel/mxc4005.c | 358 ++++++++++++++++++++++++++++++++++++++++++++
> 3 files changed, 371 insertions(+)
> create mode 100644 drivers/iio/accel/mxc4005.c
>
> diff --git a/drivers/iio/accel/Kconfig b/drivers/iio/accel/Kconfig
> index a59047d..69302be 100644
> --- a/drivers/iio/accel/Kconfig
> +++ b/drivers/iio/accel/Kconfig
> @@ -137,6 +137,17 @@ config MMA9553
> To compile this driver as a module, choose M here: the module
> will be called mma9553.
>
> +config MXC4005
> + tristate "Memsic MXC4005XC 3-Axis Accelerometer Driver"
> + depends on I2C
> + select REGMAP_I2C
> + help
> + Say yes here to build support for the Memsic MXC4005XC 3-axis
> + accelerometer.
> +
> + To compile this driver as a module, choose M. The module will be
> + called mxc4005.
> +
> config STK8312
> tristate "Sensortek STK8312 3-Axis Accelerometer Driver"
> depends on I2C
> diff --git a/drivers/iio/accel/Makefile b/drivers/iio/accel/Makefile
> index ebd2675..020dda0 100644
> --- a/drivers/iio/accel/Makefile
> +++ b/drivers/iio/accel/Makefile
> @@ -14,6 +14,8 @@ obj-$(CONFIG_MMA9551_CORE) += mma9551_core.o
> obj-$(CONFIG_MMA9551) += mma9551.o
> obj-$(CONFIG_MMA9553) += mma9553.o
>
> +obj-$(CONFIG_MXC4005) += mxc4005.o
> +
> obj-$(CONFIG_STK8312) += stk8312.o
> obj-$(CONFIG_STK8BA50) += stk8ba50.o
>
> diff --git a/drivers/iio/accel/mxc4005.c b/drivers/iio/accel/mxc4005.c
> new file mode 100644
> index 0000000..76a7954
> --- /dev/null
> +++ b/drivers/iio/accel/mxc4005.c
> @@ -0,0 +1,358 @@
> +/*
> + * 3-axis accelerometer driver for MXC4005XC Memsic sensor
> + *
> + * Copyright (c) 2014, Intel Corporation.
> + *
> + * 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.
> + *
> + * This program is distributed in the hope it will be useful, but WITHOUT
> + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
> + * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
> + * more details.
> + */
> +
> +#include <linux/module.h>
> +#include <linux/i2c.h>
> +#include <linux/iio/iio.h>
> +#include <linux/acpi.h>
> +#include <linux/regmap.h>
> +#include <linux/iio/sysfs.h>
> +
> +#define MXC4005_DRV_NAME "mxc4005"
> +#define MXC4005_REGMAP_NAME "mxc4005_regmap"
You don't actually use the above... Guessing you did mean
to but used drv_name instead in the regmap configuration.
> +
> +#define MXC4005_REG_XOUT_UPPER 0x03
> +#define MXC4005_REG_XOUT_LOWER 0x04
> +#define MXC4005_REG_YOUT_UPPER 0x05
> +#define MXC4005_REG_YOUT_LOWER 0x06
> +#define MXC4005_REG_ZOUT_UPPER 0x07
> +#define MXC4005_REG_ZOUT_LOWER 0x08
> +
> +#define MXC4005_REG_CONTROL 0x0D
> +#define MXC4005_REG_CONTROL_MASK_FSR GENMASK(6, 5)
> +#define MXC4005_CONTROL_FSR_SHIFT 5
> +
> +#define MXC4005_REG_DEVICE_ID 0x0E
> +
> +enum mxc4005_axis {
> + AXIS_X,
> + AXIS_Y,
> + AXIS_Z,
> +};
> +
> +enum mxc4005_range {
> + MXC4005_RANGE_2G,
> + MXC4005_RANGE_4G,
> + MXC4005_RANGE_8G,
> +};
> +
> +struct mxc4005_data {
> + struct i2c_client *client;
In a regmap cleanup series someone posted the other day,
they just put struct device *dev in here instead and
assigned data.dev = client->dev;

Result is slightly cleaner code. Worth doing here?

> + struct mutex mutex;
> + struct regmap *regmap;
> +};
> +
> +/*
> + * MXC4005 can operate in the following ranges:
> + * +/- 2G, 4G, 8G (the default +/-2G)
> + *
> + * (2 + 2) * 9.81 / (2^12 - 1) = 0.009582
> + * (4 + 4) * 9.81 / (2^12 - 1) = 0.019164
> + * (8 + 8) * 9.81 / (2^12 - 1) = 0.038329
> + */
> +static const struct {
> + u8 range;
> + int scale;
> +} mxc4005_scale_table[] = {
> + {MXC4005_RANGE_2G, 9582},
> + {MXC4005_RANGE_4G, 19164},
> + {MXC4005_RANGE_8G, 38329},
> +};
> +
> +
> +static IIO_CONST_ATTR(in_accel_scale_available, "0.009582 0.019164 0.038329");
> +
> +static struct attribute *mxc4005_attributes[] = {
> + &iio_const_attr_in_accel_scale_available.dev_attr.attr,
> + NULL,
> +};
> +
> +static const struct attribute_group mxc4005_attrs_group = {
> + .attrs = mxc4005_attributes,
> +};
> +
> +static bool mxc4005_is_readable_reg(struct device *dev, unsigned int reg)
> +{
> + switch (reg) {
> + case MXC4005_REG_XOUT_UPPER:
> + case MXC4005_REG_XOUT_LOWER:
> + case MXC4005_REG_YOUT_UPPER:
> + case MXC4005_REG_YOUT_LOWER:
> + case MXC4005_REG_ZOUT_UPPER:
> + case MXC4005_REG_ZOUT_LOWER:
> + case MXC4005_REG_DEVICE_ID:
> + case MXC4005_REG_CONTROL:
> + return true;
> + default:
> + return false;
> + }
> +}
> +
> +static bool mxc4005_is_writeable_reg(struct device *dev, unsigned int reg)
> +{
> + switch (reg) {
> + case MXC4005_REG_CONTROL:
> + return true;
> + default:
> + return false;
> + }
> +}
> +
> +static const struct regmap_config mxc4005_regmap_config = {
> + .name = MXC4005_DRV_NAME,
> +
> + .reg_bits = 8,
> + .val_bits = 8,
> +
> + .max_register = MXC4005_REG_DEVICE_ID,
> + .cache_type = REGCACHE_NONE,
REGCACHE_NONE is the default. No need to specify it here.
(enum value of 0)
> +
> + .readable_reg = mxc4005_is_readable_reg,
> + .writeable_reg = mxc4005_is_writeable_reg,
> +};
> +
> +static int mxc4005_read_axis(struct mxc4005_data *data,
> + unsigned int addr)
> +{
> + __be16 reg;
> + int ret;
> +
> + ret = regmap_bulk_read(data->regmap, addr, (u8 *) &reg, sizeof(reg));
> + if (ret < 0) {
> + dev_err(&data->client->dev, "failed to read reg %02x\n", addr);
> + return ret;
> + }
> +
> + return be16_to_cpu(reg);
> +}
> +
> +static int mxc4005_read_scale(struct mxc4005_data *data)
> +{
> + unsigned int reg;
> + int ret;
> + int i;
> +
> + ret = regmap_read(data->regmap, MXC4005_REG_CONTROL, &reg);
> + if (ret < 0) {
> + dev_err(&data->client->dev, "failed to read reg_control\n");
> + return ret;
> + }
> +
> + i = reg >> MXC4005_CONTROL_FSR_SHIFT;
> +
> + if (i < 0 || i >= ARRAY_SIZE(mxc4005_scale_table))
> + return -EINVAL;
> +
> + return mxc4005_scale_table[i].scale;
> +}
> +
> +static int mxc4005_set_scale(struct mxc4005_data *data, int val)
> +{
> + unsigned int reg;
> + int i;
> + int ret;
> +
> + for (i = 0; i < ARRAY_SIZE(mxc4005_scale_table); i++) {
> + if (mxc4005_scale_table[i].scale == val) {
> + reg = i << MXC4005_CONTROL_FSR_SHIFT;
> + ret = regmap_update_bits(data->regmap,
> + MXC4005_REG_CONTROL,
> + MXC4005_REG_CONTROL_MASK_FSR,
> + reg);
> + if (ret < 0)
> + dev_err(&data->client->dev,
> + "failed to write reg_control\n");
> + return ret;
> + }
> + }
> +
> + return -EINVAL;
> +}
> +
> +static int mxc4005_read_raw(struct iio_dev *indio_dev,
> + struct iio_chan_spec const *chan,
> + int *val, int *val2, long mask)
> +{
> + struct mxc4005_data *data = iio_priv(indio_dev);
> + int ret;
> +
> + switch (mask) {
> + case IIO_CHAN_INFO_RAW:
> + switch (chan->type) {
> + case IIO_ACCEL:
> + if (iio_buffer_enabled(indio_dev))
> + return -EBUSY;
> +
> + ret = mxc4005_read_axis(data, chan->address);
> + if (ret < 0)
> + return ret;
> + *val = sign_extend32(ret >> 4, 11);
> + return IIO_VAL_INT;
> + default:
> + return -EINVAL;
> + }
> + case IIO_CHAN_INFO_SCALE:
> + ret = mxc4005_read_scale(data);
> + if (ret < 0)
> + return ret;
> +
> + *val = 0;
> + *val2 = ret;
> + return IIO_VAL_INT_PLUS_MICRO;
> + default:
> + return -EINVAL;
> + }
> +}
> +
> +static int mxc4005_write_raw(struct iio_dev *indio_dev,
> + struct iio_chan_spec const *chan,
> + int val, int val2, long mask)
> +{
> + struct mxc4005_data *data = iio_priv(indio_dev);
> +
> + switch (mask) {
> + case IIO_CHAN_INFO_SCALE:
> + if (val != 0)
> + return -EINVAL;
> +
> + return mxc4005_set_scale(data, val2);
> + default:
> + return -EINVAL;
> + }
> +}
> +
> +static const struct iio_info mxc4005_info = {
> + .driver_module = THIS_MODULE,
> + .read_raw = mxc4005_read_raw,
> + .write_raw = mxc4005_write_raw,
> + .attrs = &mxc4005_attrs_group,
> +};
> +
> +#define MXC4005_CHANNEL(_axis, _addr) { \
> + .type = IIO_ACCEL, \
> + .modified = 1, \
> + .channel2 = IIO_MOD_##_axis, \
> + .address = _addr, \
> + .info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \
> + .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE), \
> +}
> +
> +static const struct iio_chan_spec mxc4005_channels[] = {
> + MXC4005_CHANNEL(X, MXC4005_REG_XOUT_UPPER),
> + MXC4005_CHANNEL(Y, MXC4005_REG_YOUT_UPPER),
> + MXC4005_CHANNEL(Z, MXC4005_REG_ZOUT_UPPER),
> +};
> +
> +static int mxc4005_chip_init(struct mxc4005_data *data)
> +{
> + int ret;
> + unsigned int reg;
> +
> + ret = regmap_read(data->regmap, MXC4005_REG_DEVICE_ID, &reg);
> + if (ret < 0) {
> + dev_err(&data->client->dev, "failed to read chip id\n");
> + return ret;
> + }
> +
> + dev_dbg(&data->client->dev, "MXC4005 chip id %02x\n", reg);
> +
> + return 0;
> +}
> +
> +static int mxc4005_probe(struct i2c_client *client,
> + const struct i2c_device_id *id)
> +{
> + struct mxc4005_data *data;
> + struct iio_dev *indio_dev;
> + struct regmap *regmap;
> + int ret;
> +
> + indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*data));
> + if (!indio_dev)
> + return -ENOMEM;
> +
> + regmap = devm_regmap_init_i2c(client, &mxc4005_regmap_config);
> + if (IS_ERR(regmap)) {
> + dev_err(&client->dev, "failed to initialize regmap\n");
> + return PTR_ERR(regmap);
> + }
> +
> + data = iio_priv(indio_dev);
> + i2c_set_clientdata(client, indio_dev);
> + data->client = client;
> + data->regmap = regmap;
> +
> + ret = mxc4005_chip_init(data);
> + if (ret < 0) {
For consistency with previous error message (yeah I'm getting
picky ;) - initialize
> + dev_err(&client->dev, "failed to init chip\n");
> + return ret;
> + }
> +
> + mutex_init(&data->mutex);
> +
> + indio_dev->dev.parent = &client->dev;
> + indio_dev->channels = mxc4005_channels;
> + indio_dev->num_channels = ARRAY_SIZE(mxc4005_channels);
> + indio_dev->name = MXC4005_DRV_NAME;
> + indio_dev->modes = INDIO_DIRECT_MODE;
> + indio_dev->info = &mxc4005_info;
> +
> + ret = iio_device_register(indio_dev);
> + if (ret < 0) {
> + dev_err(&client->dev,
> + "unable to register iio device %d\n", ret);
> + return ret;
> + }
> +
> + return 0;
> +}
> +
> +static int mxc4005_remove(struct i2c_client *client)
> +{
> + struct iio_dev *indio_dev = i2c_get_clientdata(client);
> +
Roll the line above and the one below into one. No point in the
separation.
> + iio_device_unregister(indio_dev);
> +
> + return 0;
> +}
> +
> +static const struct acpi_device_id mxc4005_acpi_match[] = {
> + {"MXC4005", 0},
> + { },
> +};
> +MODULE_DEVICE_TABLE(acpi, mxc4005_acpi_match);
> +
> +static const struct i2c_device_id mxc4005_id[] = {
> + {"mxc4005", 0},
> + { },
> +};
For consistency no blank line here.
> +
> +MODULE_DEVICE_TABLE(i2c, mxc4005_id);
> +
> +static struct i2c_driver mxc4005_driver = {
> + .driver = {
> + .name = MXC4005_DRV_NAME,
> + .acpi_match_table = ACPI_PTR(mxc4005_acpi_match),
> + },
> + .probe = mxc4005_probe,
> + .remove = mxc4005_remove,
> + .id_table = mxc4005_id,
> +};
> +
> +module_i2c_driver(mxc4005_driver);
> +
> +MODULE_AUTHOR("Teodora Baluta <teodora.baluta@xxxxxxxxx>");
> +MODULE_LICENSE("GPL v2");
> +MODULE_DESCRIPTION("MXC4005 3-axis accelerometer driver");
>

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