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Date: Sun, 6 Oct 2019 09:38:55 +0100
From: Jonathan Cameron <jic23@...nel.org>
To: Dan Robertson <dan@...obertson.com>
Cc: linux-iio@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/1] iio: (bma400) add driver for the BMA400
On Wed, 25 Sep 2019 01:39:41 +0000
Dan Robertson <dan@...obertson.com> wrote:
> Add a IIO driver for the Bosch BMA400 3-axes ultra-low power accelerometer.
> The driver supports reading from the acceleration and temperature
> registers. The driver also supports reading and configuring the output data
> rate, oversampling ratio, and scale.
>
> Signed-off-by: Dan Robertson <dan@...obertson.com>
Hi Dan,
So my first thought was that Bosch have been moderately good at keeping their
interfaces consistent across generations. Seems not this time from
a quick look!
Minor stuff inline. Quite a bit of it is stylistic rather than functional.
I'm a lazy maintainer and tend to end up reading a lot of code so want to
think as little as possible ;)
I'd also expect a modern driver to have DT bindings. Might let that go if
it was being used with ACPI but neither is true here.
Thanks,
Jonathan
> ---
> drivers/iio/accel/Kconfig | 19 +
> drivers/iio/accel/Makefile | 2 +
> drivers/iio/accel/bma400.h | 74 +++
> drivers/iio/accel/bma400_core.c | 862 ++++++++++++++++++++++++++++++++
> drivers/iio/accel/bma400_i2c.c | 54 ++
> 5 files changed, 1011 insertions(+)
> create mode 100644 drivers/iio/accel/bma400.h
> create mode 100644 drivers/iio/accel/bma400_core.c
> create mode 100644 drivers/iio/accel/bma400_i2c.c
>
> diff --git a/drivers/iio/accel/Kconfig b/drivers/iio/accel/Kconfig
> index 9b9656ce37e6..cca6727e037e 100644
> --- a/drivers/iio/accel/Kconfig
> +++ b/drivers/iio/accel/Kconfig
> @@ -112,6 +112,25 @@ config BMA220
> To compile this driver as a module, choose M here: the
> module will be called bma220_spi.
>
> +config BMA400
> + tristate "Bosch BMA400 3-Axis Accelerometer Driver"
> + depends on I2C
> + select REGMAP
> + select BMA400_I2C if (I2C)
> + help
> + Say Y here if you want to build a driver for the Bosch BMA400
> + triaxial acceleration sensor.
> +
> + To compile this driver as a module, choose M here: the
> + module will be called bma400_core and you will also get
> + bma400_i2c for I2C
> +
> +config BMA400_I2C
> + tristate
> + depends on BMA400
> + depends on I2C
> + select REGMAP_I2C
> +
> config BMC150_ACCEL
> tristate "Bosch BMC150 Accelerometer Driver"
> select IIO_BUFFER
> diff --git a/drivers/iio/accel/Makefile b/drivers/iio/accel/Makefile
> index 56bd0215e0d4..3a051cf37f40 100644
> --- a/drivers/iio/accel/Makefile
> +++ b/drivers/iio/accel/Makefile
> @@ -14,6 +14,8 @@ obj-$(CONFIG_ADXL372_I2C) += adxl372_i2c.o
> obj-$(CONFIG_ADXL372_SPI) += adxl372_spi.o
> obj-$(CONFIG_BMA180) += bma180.o
> obj-$(CONFIG_BMA220) += bma220_spi.o
> +obj-$(CONFIG_BMA400) += bma400_core.o
> +obj-$(CONFIG_BMA400_I2C) += bma400_i2c.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
> diff --git a/drivers/iio/accel/bma400.h b/drivers/iio/accel/bma400.h
> new file mode 100644
> index 000000000000..7fa92bc457f6
> --- /dev/null
> +++ b/drivers/iio/accel/bma400.h
> @@ -0,0 +1,74 @@
> +/* SPDX-License-Identifier: GPL-2.0-only */
> +/*
> + * bma400.h - Register constants and other forward declarations
> + * needed by the bma400 sources.
> + *
> + * Copyright 2019 Dan Robertson <dan@...obertson.com>
> + *
Blank line not needed.
> + */
> +
> +#include <linux/regmap.h>
> +
> +/*
> + * Read-Only Registers
> + */
> +
> +/* Status and ID registers */
> +#define BMA400_CHIP_ID_REG 0x00
> +#define BMA400_ERR_REG 0x02
> +#define BMA400_STATUS_REG 0x03
> +
> +/* Acceleration registers */
> +#define BMA400_X_AXIS_LSB_REG 0x04
> +#define BMA400_X_AXIS_MSB_REG 0x05
> +#define BMA400_Y_AXIS_LSB_REG 0x06
> +#define BMA400_Y_AXIS_MSB_REG 0x07
> +#define BMA400_Z_AXIS_LSB_REG 0x08
> +#define BMA400_Z_AXIS_MSB_REG 0x09
> +
> +/* Sensort time registers */
> +#define BMA400_SENSOR_TIME0 0x0a
> +#define BMA400_SENSOR_TIME1 0x0b
> +#define BMA400_SENSOR_TIME2 0x0c
> +
> +/* Event and interrupt registers */
> +#define BMA400_EVENT_REG 0x0d
> +#define BMA400_INT_STAT0_REG 0x0e
> +#define BMA400_INT_STAT1_REG 0x0f
> +#define BMA400_INT_STAT2_REG 0x10
> +
> +/* Temperature register */
> +#define BMA400_TEMP_DATA_REG 0x11
> +
> +/* FIFO length and data registers */
> +#define BMA400_FIFO_LENGTH0_REG 0x12
> +#define BMA400_FIFO_LENGTH1_REG 0x13
> +#define BMA400_FIFO_DATA_REG 0x14
> +
> +/* Step count registers */
> +#define BMA400_STEP_CNT0_REG 0x15
> +#define BMA400_STEP_CNT1_REG 0x16
> +#define BMA400_STEP_CNT3_REG 0x17
> +#define BMA400_STEP_STAT_REG 0x18
> +
> +/*
> + * Read-write configuration registers
> + */
> +#define BMA400_ACC_CONFIG0_REG 0x19
> +#define BMA400_ACC_CONFIG1_REG 0x1a
> +#define BMA400_ACC_CONFIG2_REG 0x1b
> +#define BMA400_CMD_REG 0x7e
> +
> +/* Chip ID of BMA 400 devices found in the chip ID register. */
> +#define BMA400_ID_REG_VAL 0x90
> +
> +/* The softreset command */
> +#define BMA400_SOFTRESET_CMD 0xb6
> +
> +extern const struct regmap_config bma400_regmap_config;
> +
> +int bma400_probe(struct device *dev,
> + struct regmap *regmap,
> + const char *name);
> +
> +int bma400_remove(struct device *dev);
> diff --git a/drivers/iio/accel/bma400_core.c b/drivers/iio/accel/bma400_core.c
> new file mode 100644
> index 000000000000..55fe2f220c30
> --- /dev/null
> +++ b/drivers/iio/accel/bma400_core.c
> @@ -0,0 +1,862 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/*
> + * bma400-core.c - Core IIO driver for Bosch BMA400 triaxial acceleration
> + * sensor. Used by bma400-i2c.
> + *
> + * Copyright 2019 Dan Robertson <dan@...obertson.com>
> + *
> + * TODO:
> + * - Support for power management
> + * - Support events and interrupts
> + * - Create channel the step count
> + * - Create channel for sensor time
> + */
> +
> +#include <linux/device.h>
> +#include <linux/module.h>
> +#include <linux/regmap.h>
> +#include <linux/bitops.h>
> +#include <linux/iio/iio.h>
> +#include <linux/iio/sysfs.h>
> +
> +#include "bma400.h"
> +
> +/*
> + * The G-range selection may be one of 2g, 4g, 8, or 16g. The scale may
> + * be selected with the acc_range bits of the ACC_CONFIG1 register.
> + */
> +const int bma400_scale_table[] = { 38344, 76590, 153277, 306457 };
> +
> +struct bma400_sample_freq {
> + int hz;
> + int micro_hz;
> +};
> +
> +/* See the ACC_CONFIG1 section of the datasheet */
> +const struct bma400_sample_freq bma400_sample_freqs[] = {
> + { .hz = 12, .micro_hz = 500000 },
> + { .hz = 25, .micro_hz = 0 },
> + { .hz = 50, .micro_hz = 0 },
> + { .hz = 100, .micro_hz = 0 },
> + { .hz = 200, .micro_hz = 0 },
> + { .hz = 400, .micro_hz = 0 },
> + { .hz = 800, .micro_hz = 0 },
> +};
> +
> +/* See the ACC_CONFIG0 section of the datasheet */
> +enum bma400_power_mode {
> + POWER_MODE_SLEEP = 0x00,
> + POWER_MODE_LOW = 0x01,
> + POWER_MODE_NORMAL = 0x02,
> + POWER_MODE_INVALID = 0x03,
> +};
> +
> +struct bma400_data {
> + struct device *dev;
> + struct mutex mutex; /* data register lock */
> + struct iio_mount_matrix orientation;
> + struct regmap *regmap;
> + enum bma400_power_mode power_mode;
> + const struct bma400_sample_freq *sample_freq;
> + int oversampling_ratio;
> + int scale;
> +};
> +
> +static bool bma400_is_writable_reg(struct device *dev, unsigned int reg)
> +{
> + switch (reg) {
> + case BMA400_CHIP_ID_REG:
> + case BMA400_ERR_REG:
> + case BMA400_STATUS_REG:
> + case BMA400_X_AXIS_LSB_REG:
> + case BMA400_X_AXIS_MSB_REG:
> + case BMA400_Y_AXIS_LSB_REG:
> + case BMA400_Y_AXIS_MSB_REG:
> + case BMA400_Z_AXIS_LSB_REG:
> + case BMA400_Z_AXIS_MSB_REG:
> + case BMA400_SENSOR_TIME0:
> + case BMA400_SENSOR_TIME1:
> + case BMA400_SENSOR_TIME2:
> + case BMA400_EVENT_REG:
> + case BMA400_INT_STAT0_REG:
> + case BMA400_INT_STAT1_REG:
> + case BMA400_INT_STAT2_REG:
> + case BMA400_TEMP_DATA_REG:
> + case BMA400_FIFO_LENGTH0_REG:
> + case BMA400_FIFO_LENGTH1_REG:
> + case BMA400_FIFO_DATA_REG:
> + case BMA400_STEP_CNT0_REG:
> + case BMA400_STEP_CNT1_REG:
> + case BMA400_STEP_CNT3_REG:
> + case BMA400_STEP_STAT_REG:
> + return false;
> + default:
> + return true;
> + }
> +}
> +
> +static bool bma400_is_volatile_reg(struct device *dev, unsigned int reg)
> +{
> + switch (reg) {
> + case BMA400_ERR_REG:
> + case BMA400_STATUS_REG:
> + case BMA400_X_AXIS_LSB_REG:
> + case BMA400_X_AXIS_MSB_REG:
> + case BMA400_Y_AXIS_LSB_REG:
> + case BMA400_Y_AXIS_MSB_REG:
> + case BMA400_Z_AXIS_LSB_REG:
> + case BMA400_Z_AXIS_MSB_REG:
> + case BMA400_SENSOR_TIME0:
> + case BMA400_SENSOR_TIME1:
> + case BMA400_SENSOR_TIME2:
> + case BMA400_EVENT_REG:
> + case BMA400_INT_STAT0_REG:
> + case BMA400_INT_STAT1_REG:
> + case BMA400_INT_STAT2_REG:
> + case BMA400_TEMP_DATA_REG:
> + case BMA400_FIFO_LENGTH0_REG:
> + case BMA400_FIFO_LENGTH1_REG:
> + case BMA400_FIFO_DATA_REG:
> + case BMA400_STEP_CNT0_REG:
> + case BMA400_STEP_CNT1_REG:
> + case BMA400_STEP_CNT3_REG:
> + case BMA400_STEP_STAT_REG:
> + return true;
> + default:
> + return false;
> + }
> +}
> +
> +const struct regmap_config bma400_regmap_config = {
> + .reg_bits = 8,
> + .val_bits = 8,
> + .max_register = BMA400_CMD_REG,
> + .cache_type = REGCACHE_RBTREE,
> + .writeable_reg = bma400_is_writable_reg,
> + .volatile_reg = bma400_is_volatile_reg,
> +};
> +EXPORT_SYMBOL(bma400_regmap_config);
> +
> +static const struct iio_mount_matrix *
> +bma400_accel_get_mount_matrix(const struct iio_dev *indio_dev,
> + const struct iio_chan_spec *chan)
> +{
> + struct bma400_data *data = iio_priv(indio_dev);
> +
> + return &data->orientation;
> +}
> +
> +static const struct iio_chan_spec_ext_info bma400_ext_info[] = {
> + IIO_MOUNT_MATRIX(IIO_SHARED_BY_DIR, bma400_accel_get_mount_matrix),
> + { }
> +};
> +
> +#define BMA400_ACC_CHANNEL(_axis) { \
> + .type = IIO_ACCEL, \
> + .modified = 1, \
> + .channel2 = IIO_MOD_##_axis, \
> + .info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \
> + .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SAMP_FREQ) | \
> + BIT(IIO_CHAN_INFO_SCALE) | \
> + BIT(IIO_CHAN_INFO_OVERSAMPLING_RATIO), \
> + .ext_info = bma400_ext_info \
> +}
> +
> +static const struct iio_chan_spec bma400_channels[] = {
> + BMA400_ACC_CHANNEL(X),
> + BMA400_ACC_CHANNEL(Y),
> + BMA400_ACC_CHANNEL(Z),
> + {
> + .type = IIO_TEMP,
> + .info_mask_separate = BIT(IIO_CHAN_INFO_PROCESSED),
> + .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SAMP_FREQ),
> + },
> +};
> +
> +static int bma400_get_temp_reg(struct bma400_data *data, int *val, int *val2)
> +{
> + int ret;
> + int host_temp;
> + unsigned int raw_temp;
> +
> + if (data->power_mode == POWER_MODE_SLEEP)
> + return -EBUSY;
> +
> + ret = regmap_read(data->regmap, BMA400_TEMP_DATA_REG, &raw_temp);
> +
> + if (!ret) {
Error path out of line, not the good one. See below.
> + host_temp = sign_extend32(raw_temp, 7);
> + /*
> + * The formula for the TEMP_DATA register in the datasheet
> + * is: x * 0.5 + 23
> + */
> + *val = (host_temp >> 1) + 23;
> + *val2 = (host_temp & 0x1) * 500000;
> + ret = IIO_VAL_INT_PLUS_MICRO;
> + }
> + return ret;
> +}
> +
> +static int bma400_get_accel_reg(struct bma400_data *data,
> + const struct iio_chan_spec *chan,
> + int *val)
> +{
> + int ret;
> + u16 lsb_reg;
> + __le16 raw_accel = 0;
I don't think we need the assignment... Is there a compiler that
can't figure that out?
> +
> + if (data->power_mode == POWER_MODE_SLEEP)
> + return -EBUSY;
> +
> + switch (chan->channel2) {
> + case IIO_MOD_X:
> + lsb_reg = BMA400_X_AXIS_LSB_REG;
> + break;
> + case IIO_MOD_Y:
> + lsb_reg = BMA400_Y_AXIS_LSB_REG;
> + break;
> + case IIO_MOD_Z:
> + lsb_reg = BMA400_Z_AXIS_LSB_REG;
> + break;
> + default:
> + dev_err(data->dev, "invalid axis channel modifier");
> + return -EINVAL;
> + }
> +
> + /* bulk read two registers, with the base being the LSB register */
> + ret = regmap_bulk_read(data->regmap, lsb_reg, &raw_accel, 2);
> + if (!ret) {
Same point as below on error path out of line.
> + *val = sign_extend32(le16_to_cpu(raw_accel), 11);
> + ret = IIO_VAL_INT;
> + }
> +
> + return ret;
> +}
> +
> +static int bma400_ready_for_cmd(struct bma400_data *data)
> +{
> + unsigned int val;
> + int ret = regmap_read(data->regmap, BMA400_STATUS_REG, &val);
> +
> + if (ret < 0 || !(val & 0x10))
> + return 0;
> +
> + return 1;
Maybe... (up to you on this one as I'm not convinced this is better :)
if (ret < 0)
return 0;
return (val & 0x10) ? 1 : 0;
Separates the error case from checking the parameter.
> +}
> +
> +static int bma400_softreset(struct bma400_data *data)
> +{
> + int ret;
> +
> + if (!bma400_ready_for_cmd(data))
> + return -EAGAIN;
> +
> + ret = regmap_write(data->regmap, BMA400_CMD_REG,
> + BMA400_SOFTRESET_CMD);
> + if (!ret) {
As below, prefer the error path indented even if it costs a line or two of
code.
if (ret)
return ret;
data->...
> + /* a softreset restores registers to their defaults */
> + data->power_mode = POWER_MODE_SLEEP;
> + data->sample_freq = NULL;
> + data->oversampling_ratio = -1;
> + data->scale = bma400_scale_table[0];
> + }
> + return ret;
> +}
> +
> +static int bma400_get_acc_config0_reg(struct bma400_data *data)
> +{
I'm unconvinced these wrappers add anything. Just do the regmap_read
inline.
> + int ret;
> + unsigned int val;
> +
> + ret = regmap_read(data->regmap, BMA400_ACC_CONFIG0_REG,
> + &val);
> + if (ret < 0) {
> + dev_err(data->dev, "Failed read acc_config0");
> + return ret;
> + }
> +
> + return val;
> +}
> +
> +static int bma400_get_acc_config1_reg(struct bma400_data *data)
> +{
> + int ret;
> + unsigned int val;
> +
> + ret = regmap_read(data->regmap, BMA400_ACC_CONFIG1_REG,
> + &val);
> + if (ret < 0) {
> + dev_err(data->dev, "Failed read acc_config1");
> + return ret;
> + }
> +
> + return val;
> +}
> +
> +static int bma400_get_accel_output_data_rate(struct bma400_data *data)
> +{
> + int acc_config1;
> + unsigned int odr;
> + int idx;
> +
> + switch (data->power_mode) {
> + case POWER_MODE_LOW:
> + /*
> + * Runs at a fixed rate in low-power mode. See section 4.3
> + * in the datasheet.
> + */
> + data->sample_freq = &bma400_sample_freqs[1];
> + return 0;
> + case POWER_MODE_NORMAL:
> + /*
> + * In normal mode the ODR can be found in the ACC_CONFIG1
> + * register.
> + */
> + acc_config1 = bma400_get_acc_config1_reg(data);
> + if (acc_config1 < 0) {
> + data->sample_freq = NULL;
> + return acc_config1;
> + }
> +
> + odr = (acc_config1 & 0x0f);
> + if (odr < 0x05 || odr > 0x0b) {
> + dev_err(data->dev, "invalid ODR=%x", odr);
> + data->sample_freq = NULL;
> + return -EINVAL;
> + }
> + idx = odr - 0x05;
> +
> + data->sample_freq = &bma400_sample_freqs[idx];
> + return 0;
> + default:
> + data->sample_freq = NULL;
> + return 0;
> + }
> +}
> +
> +static int bma400_get_accel_output_data_rate_idx(struct bma400_data *data,
> + int hz, int uhz)
> +{
> + int i;
> + const struct bma400_sample_freq *sample_freq;
> +
> + for (i = 0; i < ARRAY_SIZE(bma400_sample_freqs); ++i) {
> + sample_freq = &bma400_sample_freqs[i];
> + if (sample_freq->hz == hz &&
> + sample_freq->micro_hz == uhz)
> + return i;
> + }
> +
> + return -EINVAL;
> +}
> +
> +static int bma400_set_accel_output_data_rate(struct bma400_data *data,
> + int hz, int uhz)
> +{
> + int acc_config1;
> + unsigned int odr;
> + int idx;
> + int ret;
> +
> + idx = bma400_get_accel_output_data_rate_idx(data, hz, uhz);
> +
> + if (idx < 0)
> + return idx;
> +
> + acc_config1 = bma400_get_acc_config1_reg(data);
> +
> + if (acc_config1 < 0)
> + return acc_config1;
> +
> + /* preserve the range and normal mode osr */
> + odr = (0xf0 & acc_config1) | (idx + 0x5);
> +
> + ret = regmap_write(data->regmap, BMA400_ACC_CONFIG1_REG, odr);
> + if (!ret)
> + data->sample_freq = &bma400_sample_freqs[idx];
I'd rather we kept error flow indented even if a bit longer. It means
these fine error checks are handled the same as earlier ones and makes
reviewing a little bit easier.
if (ret)
return ret;
data->...
> +
> + return ret;
> +}
> +
> +static int bma400_get_accel_oversampling_ratio(struct bma400_data *data)
> +{
> + int acc_config;
> +
> + /*
> + * The oversampling ratio is stored in a different register
> + * based on the power-mode. In normal mode the OSR is stored
> + * in ACC_CONFIG1. In low-power mode it is stored in
> + * ACC_CONFIG0.
> + */
> + switch (data->power_mode) {
> + case POWER_MODE_LOW:
> + acc_config = bma400_get_acc_config0_reg(data);
> + if (acc_config < 0) {
> + data->oversampling_ratio = -1;
> + return acc_config;
> + }
> +
> + data->oversampling_ratio = (acc_config & 0x60) >> 5;
> + return 0;
> + case POWER_MODE_NORMAL:
> + acc_config = bma400_get_acc_config1_reg(data);
> + if (acc_config < 0) {
> + data->oversampling_ratio = -1;
> + return acc_config;
> + }
> +
> + data->oversampling_ratio = (acc_config & 0x30) >> 4;
> + return 0;
> + default:
> + data->oversampling_ratio = -1;
> + return 0;
> + }
> +}
> +
> +static int bma400_set_accel_oversampling_ratio(struct bma400_data *data,
> + int val)
> +{
> + int ret;
> + int acc_config;
> +
> + /* The oversampling ratio is a two bit field */
> + if (val & ~0x3)
Use a define for that mask. Then we don't need the comment.
> + return -EINVAL;
> +
> + /* The oversampling ratio is stored in a different register
Most of the kernel, including iio, use
/*
* The...
* ..
*/
> + * based on the power-mode.
> + */
> + switch (data->power_mode) {
> + case POWER_MODE_LOW:
> + acc_config = bma400_get_acc_config0_reg(data);
> + if (acc_config < 0)
> + return acc_config;
> +
> + ret = regmap_write(data->regmap, BMA400_ACC_CONFIG0_REG,
> + (acc_config & 0x9f) | (val << 5));
Use defines for these masks.
> + if (ret < 0)
> + dev_err(data->dev, "Failed to write out OSR");
> + else
> + data->oversampling_ratio = val;
> + break;
> + case POWER_MODE_NORMAL:
> + acc_config = bma400_get_acc_config1_reg(data);
> + if (acc_config < 0)
> + return acc_config;
> +
> + ret = regmap_write(data->regmap, BMA400_ACC_CONFIG1_REG,
> + (acc_config & 0xcf) | (val << 4));
> + if (ret < 0)
> + dev_err(data->dev, "Failed to write out OSR");
> + else
> + data->oversampling_ratio = val;
Nicer (even if a little longer) to read as:
if (ret < 0) {
dev_err(data->dev, "Failed to write out OSR");
return ret;
}
data->oversampling_ration = val;
return 0;
> + break;
> + default:
> + return -EINVAL;
> + }
> + return ret;
> +}
> +
> +static int bma400_get_accel_scale(struct bma400_data *data)
> +{
> + int idx;
> + int acc_config1 = bma400_get_acc_config1_reg(data);
> +
> + if (acc_config1 < 0)
> + return acc_config1;
> +
> + idx = (acc_config1 & 0xc0) >> 6;
> + if (idx < ARRAY_SIZE(bma400_scale_table)) {
> + data->scale = bma400_scale_table[idx];
> + return 0;
Preference for error path indented in cases where it doesn't
make a substantial difference in code length.
if (idx >= ARRAY_SIZE(bma400_scale_table)
return -EINVAL;
data->scale = bma400_scale_table[idx];
return 0;
> + }
> + return -EINVAL;
> +}
> +
> +static int bma400_get_accel_scale_idx(struct bma400_data *data, int val)
> +{
> + int i;
> +
> + for (i = 0; i < ARRAY_SIZE(bma400_scale_table); ++i) {
> + if (bma400_scale_table[i] == val)
> + return i;
> + }
> + return -EINVAL;
> +}
> +
> +static int bma400_set_accel_scale(struct bma400_data *data, unsigned int val)
> +{
> + int ret;
> + int idx;
> + int acc_config1 = bma400_get_acc_config1_reg(data);
> +
> + if (acc_config1 < 0)
> + return acc_config1;
> +
> + idx = bma400_get_accel_scale_idx(data, val);
> +
> + if (idx < 0)
> + return idx;
> +
> + ret = regmap_write(data->regmap, BMA400_ACC_CONFIG1_REG,
> + (acc_config1 & 0x3f) | (idx << 6));
> + if (ret < 0)
> + return ret;
> +
> + data->scale = val;
> + return 0;
> +}
> +
> +static int bma400_get_power_mode(struct bma400_data *data)
> +{
> + int ret;
> + unsigned int val;
> +
> + ret = regmap_read(data->regmap, BMA400_STATUS_REG, &val);
> + if (ret < 0) {
> + dev_err(data->dev, "Failed to read status register");
> + return ret;
> + }
> +
> + data->power_mode = (val >> 1) & 0x03;
Blank line here and in similar cases helps readability (a tiny bit).
> + return 0;
> +}
> +
> +static int bma400_set_power_mode(struct bma400_data *data,
> + enum bma400_power_mode mode)
> +{
> + int ret;
> +
> + ret = bma400_get_acc_config0_reg(data);
> +
> + if (ret < 0)
> + return ret;
> +
> + if (data->power_mode == mode)
> + return 0;
> +
> + if (mode == POWER_MODE_INVALID)
> + return -EINVAL;
> +
> + /* Preserve the low-power oversample ratio etc */
> + ret = regmap_write(data->regmap, BMA400_ACC_CONFIG0_REG,
> + mode | (ret & 0xfc));
> +
> + if (ret < 0) {
> + dev_err(data->dev, "Failed to write to power-mode");
> + return ret;
> + }
> +
> + /* Update our cached power-mode */
Bit marginal on whether that comment adds anything not obvious from
the code. From a maintenance point of view, excess comments are
just opportunities for rot. Hence we are generally only in favour
of those that add significant value.
> + data->power_mode = mode;
> +
> + /*
> + * Update our cached osr and odr based on the new
> + * power-mode.
> + */
> + bma400_get_accel_output_data_rate(data);
> + bma400_get_accel_oversampling_ratio(data);
> +
> + return 0;
> +}
> +
> +static int bma400_init(struct bma400_data *data)
> +{
> + int ret;
> + unsigned int val;
> +
> + /* Try to read chip_id register. It must return 0x90. */
> + ret = regmap_read(data->regmap, BMA400_CHIP_ID_REG, &val);
> +
> + if (ret < 0) {
> + dev_err(data->dev, "Failed to read chip id register: %x!", ret);
> + return ret;
> + } else if (val != BMA400_ID_REG_VAL) {
> + dev_err(data->dev, "CHIP ID MISMATCH: %x!", ret);
> + return -ENODEV;
> + }
> +
> + ret = bma400_get_power_mode(data);
> + if (ret < 0) {
> + dev_err(data->dev, "Failed to get the initial power-mode!");
> + return ret;
> + }
> +
> + if (data->power_mode != POWER_MODE_NORMAL) {
> + ret = bma400_set_power_mode(data, POWER_MODE_NORMAL);
> + if (ret < 0) {
> + dev_err(data->dev, "Failed to wake up the device!");
> + return ret;
> + }
> + /*
> + * TODO: The datasheet waits 1500us here in the example, but
> + * lists 2/ODR as the wakeup time.
> + */
> + usleep_range(1500, 20000);
> + }
> +
> + ret = bma400_get_accel_output_data_rate(data);
> + if (ret < 0)
> + return ret;
> +
> + ret = bma400_get_accel_oversampling_ratio(data);
> + if (ret < 0)
> + return ret;
> +
> + ret = bma400_get_accel_scale(data);
> + if (ret < 0)
> + return ret;
> +
> + /*
> + * Once the interrupt engine is supported we might use the
> + * data_src_reg, but for now ensure this is set to the
> + * variable ODR filter selectable by the sample frequency
> + * channel.
> + */
> + return regmap_write(data->regmap, BMA400_ACC_CONFIG2_REG, 0x00);
> +}
> +
> +static ssize_t bma400_show_samp_freq_avail(struct device *dev,
> + struct device_attribute *attr,
> + char *buf)
> +{
> + int i;
> + int len = 0;
> + const struct bma400_sample_freq *sample_freq;
> +
> + for (i = 0; i < ARRAY_SIZE(bma400_sample_freqs); ++i) {
> + sample_freq = &bma400_sample_freqs[i];
> + len += scnprintf(buf + len, PAGE_SIZE - len, "%d.%06d ",
> + sample_freq->hz, sample_freq->micro_hz);
> + }
> +
> + buf[len - 1] = '\n';
> +
> + return len;
> +}
> +
> +static ssize_t bma400_show_scale_avail(struct device *dev,
> + struct device_attribute *attr,
> + char *buf)
As you are providing functions for it anyway, perhaps use the core
functions to do this?
See the docs for struct iio_info -> read_avail.
Not that many users yet as we added this for a few specific cases
that needed to query these from in kernel users.
> +{
> + int i;
> + int len = 0;
> +
> + for (i = 0; i < ARRAY_SIZE(bma400_scale_table); ++i)
> + len += scnprintf(buf + len, PAGE_SIZE - len, "0.%06d ",
> + bma400_scale_table[i]);
> +
> + buf[len - 1] = '\n';
> +
> + return len;
> +}
> +
> +static IIO_DEV_ATTR_SAMP_FREQ_AVAIL(bma400_show_samp_freq_avail);
> +
> +static IIO_DEVICE_ATTR(in_accel_scale_available, 0444,
> + bma400_show_scale_avail, NULL, 0);
> +
> +static struct attribute *bma400_attributes[] = {
> + &iio_dev_attr_sampling_frequency_available.dev_attr.attr,
> + &iio_dev_attr_in_accel_scale_available.dev_attr.attr,
> + NULL,
> +};
> +
> +static const struct attribute_group bma400_attrs_group = {
> + .attrs = bma400_attributes,
> +};
> +
> +static int bma400_read_raw(struct iio_dev *indio_dev,
> + struct iio_chan_spec const *chan, int *val,
> + int *val2, long mask)
> +{
> + struct bma400_data *data = iio_priv(indio_dev);
> + int ret;
> +
> + switch (mask) {
> + case IIO_CHAN_INFO_PROCESSED:
> + mutex_lock(&data->mutex);
> + ret = bma400_get_temp_reg(data, val, val2);
> + mutex_unlock(&data->mutex);
> + return ret;
> + case IIO_CHAN_INFO_RAW:
> + mutex_lock(&data->mutex);
> + ret = bma400_get_accel_reg(data, chan, val);
> + mutex_unlock(&data->mutex);
> + return ret;
> + case IIO_CHAN_INFO_SAMP_FREQ:
> + switch (chan->type) {
> + case IIO_ACCEL:
> + if (!data->sample_freq)
> + return -EINVAL;
> +
> + *val = data->sample_freq->hz;
> + if (!data->sample_freq->micro_hz)
> + return IIO_VAL_INT;
> +
> + *val2 = data->sample_freq->micro_hz;
> + return IIO_VAL_INT_PLUS_MICRO;
> + case IIO_TEMP:
> + /*
> + * Runs at a fixed sampling frequency. See Section 4.4
> + * of the datasheet.
> + */
> + *val = 6;
> + *val2 = 250000;
> + return IIO_VAL_INT_PLUS_MICRO;
> + default:
> + return -EINVAL;
> + }
> + case IIO_CHAN_INFO_SCALE:
> + *val = 0;
> + *val2 = data->scale;
> + return IIO_VAL_INT_PLUS_MICRO;
> + case IIO_CHAN_INFO_OVERSAMPLING_RATIO:
> + /*
> + * TODO: We could avoid this logic and returning -EINVAL here if
> + * we set both the low-power and normal mode OSR registers when
> + * we configure the device.
> + */
> + if (data->oversampling_ratio < 0)
> + return -EINVAL;
> +
> + *val = data->oversampling_ratio;
> + return IIO_VAL_INT;
> + default:
> + return -EINVAL;
> + }
> +}
> +
> +static int bma400_write_raw(struct iio_dev *indio_dev,
> + struct iio_chan_spec const *chan, int val, int val2,
> + long mask)
> +{
> + int ret;
> + struct bma400_data *data = iio_priv(indio_dev);
> +
> + switch (mask) {
> + case IIO_CHAN_INFO_SAMP_FREQ:
> + /*
> + * The sample frequency is readonly for the temperature
> + * register and a fixed value in low-power mode.
> + */
> + if (chan->type != IIO_ACCEL)
> + return -EINVAL;
> +
> + mutex_lock(&data->mutex);
> + ret = bma400_set_accel_output_data_rate(data, val, val2);
> + mutex_unlock(&data->mutex);
> + return ret;
> + case IIO_CHAN_INFO_SCALE:
> + if (val != 0)
> + return -EINVAL;
> +
> + mutex_lock(&data->mutex);
> + ret = bma400_set_accel_scale(data, val2);
> + mutex_unlock(&data->mutex);
> + return ret;
> + case IIO_CHAN_INFO_OVERSAMPLING_RATIO:
> + mutex_lock(&data->mutex);
> + ret = bma400_set_accel_oversampling_ratio(data, val);
> + mutex_unlock(&data->mutex);
> + return ret;
> + default:
> + return -EINVAL;
> + }
> +}
> +
> +static int bma400_write_raw_get_fmt(struct iio_dev *indio_dev,
> + struct iio_chan_spec const *chan,
> + long mask)
> +{
> + switch (mask) {
> + case IIO_CHAN_INFO_SAMP_FREQ:
> + return IIO_VAL_INT_PLUS_MICRO;
> + case IIO_CHAN_INFO_SCALE:
> + return IIO_VAL_INT_PLUS_MICRO;
> + case IIO_CHAN_INFO_OVERSAMPLING_RATIO:
> + return IIO_VAL_INT;
> + default:
> + return -EINVAL;
> + }
> +}
> +
> +static const struct iio_info bma400_info = {
> + .attrs = &bma400_attrs_group,
> + .read_raw = bma400_read_raw,
> + .write_raw = bma400_write_raw,
> + .write_raw_get_fmt = bma400_write_raw_get_fmt,
> +};
> +
> +int bma400_probe(struct device *dev,
> + struct regmap *regmap,
> + const char *name)
> +{
> + int ret;
> + struct bma400_data *data;
> + struct iio_dev *indio_dev;
> +
> + indio_dev = devm_iio_device_alloc(dev, sizeof(*data));
> + if (!indio_dev)
> + return -ENOMEM;
> +
> + data = iio_priv(indio_dev);
> + data->regmap = regmap;
> + data->dev = dev;
> +
> + ret = bma400_init(data);
> + if (ret < 0)
> + return ret;
> +
> + ret = iio_read_mount_matrix(dev, "mount-matrix",
> + &data->orientation);
Looks like the above will fit on one line..
> + if (ret)
> + return ret;
> +
> + mutex_init(&data->mutex);
> + indio_dev->dev.parent = dev;
> + indio_dev->name = name;
> + indio_dev->info = &bma400_info;
> + indio_dev->channels = bma400_channels;
> + indio_dev->num_channels = ARRAY_SIZE(bma400_channels);
> + indio_dev->modes = INDIO_DIRECT_MODE;
> +
> + dev_set_drvdata(dev, indio_dev);
> +
> + ret = iio_device_register(indio_dev);
> + if (ret < 0) {
> + dev_err(dev, "unable to register iio device\n");
> + return ret;
Drop the return out of the if statement and no need for the return 0 below.
> + }
> +
> + return 0;
> +}
> +EXPORT_SYMBOL(bma400_probe);
> +
> +int bma400_remove(struct device *dev)
> +{
> + int ret;
> + struct iio_dev *indio_dev = dev_get_drvdata(dev);
> + struct bma400_data *data = iio_priv(indio_dev);
> +
> + mutex_lock(&data->mutex);
> + ret = bma400_softreset(data);
> + if (ret < 0) {
> + /*
> + * If the softreset failed, try to put the device in
> + * sleep mode, but still report the error.
> + */
> + dev_err(data->dev, "Failed to reset the device");
> + bma400_set_power_mode(data, POWER_MODE_SLEEP);
> + }
> + mutex_unlock(&data->mutex);
> +
> + iio_device_unregister(indio_dev);
> +
> + return ret;
> +}
> +EXPORT_SYMBOL(bma400_remove);
> +
> +MODULE_AUTHOR("Dan Robertson <dan@...obertson.com>");
> +MODULE_DESCRIPTION("Bosch BMA400 triaxial acceleration sensor");
> +MODULE_LICENSE("GPL");
> diff --git a/drivers/iio/accel/bma400_i2c.c b/drivers/iio/accel/bma400_i2c.c
> new file mode 100644
> index 000000000000..227012a32e13
> --- /dev/null
> +++ b/drivers/iio/accel/bma400_i2c.c
> @@ -0,0 +1,54 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/*
> + * bma400-i2c.c - I2C IIO driver for Bosch BMA400 triaxial acceleration sensor.
> + *
> + * Copyright 2019 Dan Robertson <dan@...obertson.com>
> + *
> + * I2C address is either 0x14 or 0x15 depending on SDO
> + *
This blank line doesn't add anything (nitpick)
> + */
> +#include <linux/module.h>
> +#include <linux/i2c.h>
> +#include <linux/acpi.h>
Slight preference for alphabetical order. Also why ACPI?
> +#include <linux/of.h>
> +#include <linux/regmap.h>
> +
> +#include "bma400.h"
> +
> +static int bma400_i2c_probe(struct i2c_client *client,
> + const struct i2c_device_id *id)
> +{
> + struct regmap *regmap;
> +
> + regmap = devm_regmap_init_i2c(client,
> + &bma400_regmap_config);
> +
> + return bma400_probe(&client->dev, regmap, id->name);
> +}
> +
> +static int bma400_i2c_remove(struct i2c_client *client)
> +{
> + return bma400_remove(&client->dev);
> +}
> +
> +static const struct i2c_device_id bma400_i2c_ids[] = {
> + { "bma400", 0 },
> + { }
> +};
> +
> +MODULE_DEVICE_TABLE(i2c, bma400_i2c_ids);
> +
Good to have a of_device_id table as well from the start.
There is a general (but slow) move to stop using the fallback
to the i2c_device_id table.
> +static struct i2c_driver bma400_i2c_driver = {
> + .driver = {
> + .name = "bma400",
> + },
> + .probe = bma400_i2c_probe,
> + .remove = bma400_i2c_remove,
> + .id_table = bma400_i2c_ids,
> +};
> +
> +module_i2c_driver(bma400_i2c_driver);
> +
> +MODULE_AUTHOR("Dan Robertson <dan@...obertson.com>");
> +MODULE_DESCRIPTION("Bosch BMA400 triaxial acceleration sensor");
> +MODULE_LICENSE("GPL");
>
>
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