On Thu, 12 Sep 2019 10:58:34 +0000
Jean-Baptiste Maneyrol <JManeyrol@xxxxxxxxxxxxxx> wrote:
> Add helper functions to use the i2c auxiliary bus with the MPU i2c
> master block.
>
> Support only register based chip, reading and 1 byte writing. These
> will be useful for initializing magnetometers inside MPU9x50 chips.
>
> Signed-off-by: Jean-Baptiste Maneyrol <jmaneyrol@xxxxxxxxxxxxxx>
Docs should be by the implementation not in the header.
Otherwise, this looks fine I think. I'm not planning to plough through
datasheets for this set so mostly assuming you got it right ;)
Jonathan
> ---
> drivers/iio/imu/inv_mpu6050/Makefile | 3 +-
> drivers/iio/imu/inv_mpu6050/inv_mpu_aux.c | 184 ++++++++++++++++++++++
> drivers/iio/imu/inv_mpu6050/inv_mpu_aux.h | 46 ++++++
> 3 files changed, 232 insertions(+), 1 deletion(-)
> create mode 100644 drivers/iio/imu/inv_mpu6050/inv_mpu_aux.c
> create mode 100644 drivers/iio/imu/inv_mpu6050/inv_mpu_aux.h
>
> diff --git a/drivers/iio/imu/inv_mpu6050/Makefile b/drivers/iio/imu/inv_mpu6050/Makefile
> index 33bec09fee9b..2cfbd926522f 100644
> --- a/drivers/iio/imu/inv_mpu6050/Makefile
> +++ b/drivers/iio/imu/inv_mpu6050/Makefile
> @@ -4,7 +4,8 @@
> #
>
> obj-$(CONFIG_INV_MPU6050_IIO) += inv-mpu6050.o
> -inv-mpu6050-y := inv_mpu_core.o inv_mpu_ring.o inv_mpu_trigger.o
> +inv-mpu6050-y := inv_mpu_core.o inv_mpu_ring.o inv_mpu_trigger.o \
> + inv_mpu_aux.o
>
> obj-$(CONFIG_INV_MPU6050_I2C) += inv-mpu6050-i2c.o
> inv-mpu6050-i2c-y := inv_mpu_i2c.o inv_mpu_acpi.o
> diff --git a/drivers/iio/imu/inv_mpu6050/inv_mpu_aux.c b/drivers/iio/imu/inv_mpu6050/inv_mpu_aux.c
> new file mode 100644
> index 000000000000..b4907c1a8bb6
> --- /dev/null
> +++ b/drivers/iio/imu/inv_mpu6050/inv_mpu_aux.c
> @@ -0,0 +1,184 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Copyright (C) 2019 TDK-InvenSense, Inc.
> + */
> +
> +#include <linux/kernel.h>
> +#include <linux/device.h>
> +#include <linux/regmap.h>
> +#include <linux/delay.h>
> +
> +#include "inv_mpu_iio.h"
> +
> +/*
> + * i2c master auxiliary bus transfer function.
> + * Requires the i2c operations to be correctly setup before.
> + */
> +static int inv_mpu_i2c_master_xfer(const struct inv_mpu6050_state *st)
> +{
> + /* use 50hz frequency for xfer */
> + const unsigned int freq = 50;
> + const unsigned int period_ms = 1000 / freq;
> + uint8_t d;
> + unsigned int user_ctrl;
> + int ret;
> +
> + /* set sample rate */
> + d = INV_MPU6050_FIFO_RATE_TO_DIVIDER(freq);
> + ret = regmap_write(st->map, st->reg->sample_rate_div, d);
> + if (ret)
> + return ret;
> +
> + /* start i2c master */
> + user_ctrl = st->chip_config.user_ctrl | INV_MPU6050_BIT_I2C_MST_EN;
> + ret = regmap_write(st->map, st->reg->user_ctrl, user_ctrl);
> + if (ret)
> + goto error_restore_rate;
> +
> + /* wait for xfer: 1 period + half-period margin */
> + msleep(period_ms + period_ms / 2);
> +
> + /* stop i2c master */
> + user_ctrl = st->chip_config.user_ctrl;
> + ret = regmap_write(st->map, st->reg->user_ctrl, user_ctrl);
> + if (ret)
> + goto error_stop_i2c;
> +
> + /* restore sample rate */
> + d = st->chip_config.divider;
> + ret = regmap_write(st->map, st->reg->sample_rate_div, d);
> + if (ret)
> + goto error_restore_rate;
> +
> + return 0;
> +
> +error_stop_i2c:
> + regmap_write(st->map, st->reg->user_ctrl, st->chip_config.user_ctrl);
> +error_restore_rate:
> + regmap_write(st->map, st->reg->sample_rate_div, st->chip_config.divider);
> + return ret;
> +}
> +
> +int inv_mpu_aux_init(const struct inv_mpu6050_state *st)
> +{
> + unsigned int val;
> + int ret;
> +
> + /* configure i2c master */
> + val = INV_MPU6050_BITS_I2C_MST_CLK_400KHZ |
> + INV_MPU6050_BIT_WAIT_FOR_ES;
> + ret = regmap_write(st->map, INV_MPU6050_REG_I2C_MST_CTRL, val);
> + if (ret)
> + return ret;
> +
> + /* configure i2c master delay */
> + ret = regmap_write(st->map, INV_MPU6050_REG_I2C_SLV4_CTRL, 0);
> + if (ret)
> + return ret;
> +
> + val = INV_MPU6050_BIT_I2C_SLV0_DLY_EN |
> + INV_MPU6050_BIT_I2C_SLV1_DLY_EN |
> + INV_MPU6050_BIT_I2C_SLV2_DLY_EN |
> + INV_MPU6050_BIT_I2C_SLV3_DLY_EN |
> + INV_MPU6050_BIT_DELAY_ES_SHADOW;
> + return regmap_write(st->map, INV_MPU6050_REG_I2C_MST_DELAY_CTRL, val);
> +}
> +
> +/*
> + * i2c slave reading using SLV0
> + */
> +int inv_mpu_aux_read(const struct inv_mpu6050_state *st, uint8_t addr,
> + uint8_t reg, uint8_t *val, size_t size)
> +{
> + unsigned int status;
> + int ret;
> +
> + if (size > 0x0F)
> + return -EINVAL;
> +
> + /* setup i2c SLV0 control: i2c addr, register, enable + size */
> + ret = regmap_write(st->map, INV_MPU6050_REG_I2C_SLV_ADDR(0),
> + INV_MPU6050_BIT_I2C_SLV_RNW | addr);
> + if (ret)
> + return ret;
> + ret = regmap_write(st->map, INV_MPU6050_REG_I2C_SLV_REG(0), reg);
> + if (ret)
> + return ret;
> + ret = regmap_write(st->map, INV_MPU6050_REG_I2C_SLV_CTRL(0),
> + INV_MPU6050_BIT_SLV_EN | size);
> + if (ret)
> + return ret;
> +
> + /* do i2c xfer */
> + ret = inv_mpu_i2c_master_xfer(st);
> + if (ret)
> + goto error_disable_i2c;
> +
> + /* disable i2c slave */
> + ret = regmap_write(st->map, INV_MPU6050_REG_I2C_SLV_CTRL(0), 0);
> + if (ret)
> + goto error_disable_i2c;
> +
> + /* check i2c status */
> + ret = regmap_read(st->map, INV_MPU6050_REG_I2C_MST_STATUS, &status);
> + if (ret)
> + return ret;
> + if (status & INV_MPU6050_BIT_I2C_SLV0_NACK)
> + return -EIO;
> +
> + /* read data in registers */
> + return regmap_bulk_read(st->map, INV_MPU6050_REG_EXT_SENS_DATA,
> + val, size);
> +
> +error_disable_i2c:
> + regmap_write(st->map, INV_MPU6050_REG_I2C_SLV_CTRL(0), 0);
> + return ret;
> +}
> +
> +/*
> + * i2c slave writing 1 byte using SLV0
> + */
> +int inv_mpu_aux_write(const struct inv_mpu6050_state *st, uint8_t addr,
> + uint8_t reg, uint8_t val)
> +{
> + unsigned int status;
> + int ret;
> +
> + /* setup i2c SLV0 control: i2c addr, register, value, enable + size */
> + ret = regmap_write(st->map, INV_MPU6050_REG_I2C_SLV_ADDR(0), addr);
> + if (ret)
> + return ret;
> + ret = regmap_write(st->map, INV_MPU6050_REG_I2C_SLV_REG(0), reg);
> + if (ret)
> + return ret;
> + ret = regmap_write(st->map, INV_MPU6050_REG_I2C_SLV_DO(0), val);
> + if (ret)
> + return ret;
> + ret = regmap_write(st->map, INV_MPU6050_REG_I2C_SLV_CTRL(0),
> + INV_MPU6050_BIT_SLV_EN | 1);
> + if (ret)
> + return ret;
> +
> + /* do i2c xfer */
> + ret = inv_mpu_i2c_master_xfer(st);
> + if (ret)
> + goto error_disable_i2c;
> +
> + /* disable i2c slave */
> + ret = regmap_write(st->map, INV_MPU6050_REG_I2C_SLV_CTRL(0), 0);
> + if (ret)
> + goto error_disable_i2c;
> +
> + /* check i2c status */
> + ret = regmap_read(st->map, INV_MPU6050_REG_I2C_MST_STATUS, &status);
> + if (ret)
> + return ret;
> + if (status & INV_MPU6050_BIT_I2C_SLV0_NACK)
> + return -EIO;
> +
> + return 0;
> +
> +error_disable_i2c:
> + regmap_write(st->map, INV_MPU6050_REG_I2C_SLV_CTRL(0), 0);
> + return ret;
> +}
> diff --git a/drivers/iio/imu/inv_mpu6050/inv_mpu_aux.h b/drivers/iio/imu/inv_mpu6050/inv_mpu_aux.h
> new file mode 100644
> index 000000000000..bae4eab58e6c
> --- /dev/null
> +++ b/drivers/iio/imu/inv_mpu6050/inv_mpu_aux.h
> @@ -0,0 +1,46 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +/*
> + * Copyright (C) 2019 TDK-InvenSense, Inc.
> + */
> +
> +#ifndef INV_MPU_AUX_H_
> +#define INV_MPU_AUX_H_
> +
> +#include <linux/kernel.h>
> +
> +#include "inv_mpu_iio.h"
> +
> +/**
> + * inv_mpu_aux_init() - init i2c auxiliary bus
> + * @st: driver internal state
> + *
> + * Returns 0 on success, a negative error code otherwise.
> + */
> +int inv_mpu_aux_init(const struct inv_mpu6050_state *st);
> +
> +/**
> + * inv_mpu_aux_read() - read register function for i2c auxiliary bus
> + * @st: driver internal state.
> + * @addr: chip i2c Address
> + * @reg: chip register address
> + * @val: buffer for storing read bytes
> + * @size: number of bytes to read
> + *
> + * Returns 0 on success, a negative error code otherwise.
Documentation at implementation, not in the header.
Tends to rot when hidden away from the code.
> + */
> +int inv_mpu_aux_read(const struct inv_mpu6050_state *st, uint8_t addr,
> + uint8_t reg, uint8_t *val, size_t size);
> +
> +/**
> + * inv_mpu_aux_write() - write register function for i2c auxiliary bus
> + * @st: driver internal state.
> + * @addr: chip i2c Address
> + * @reg: chip register address
> + * @val: 1 byte value to write
> + *
> + * Returns 0 on success, a negative error code otherwise.
> + */
> +int inv_mpu_aux_write(const struct inv_mpu6050_state *st, uint8_t addr,
> + uint8_t reg, uint8_t val);
> +
> +#endif /* INV_MPU_AUX_H_ */
