> The AD5758 is a single channel DAC with 16-bit precision which uses the SPI
> interface that operates at clock rates up to 50MHz.
> 
> The output can be configured as voltage or current and is available on a
> single terminal.

comments below
 
> Datasheet:
> http://www.analog.com/media/en/technical-documentation/data-sheets/ad5758.pdf
> 
> Signed-off-by: Stefan Popa <stefan.p...@analog.com>
> ---
>  MAINTAINERS              |   7 +
>  drivers/iio/dac/Kconfig  |  10 +
>  drivers/iio/dac/Makefile |   1 +
>  drivers/iio/dac/ad5758.c | 826 
> +++++++++++++++++++++++++++++++++++++++++++++++
>  4 files changed, 844 insertions(+)
>  create mode 100644 drivers/iio/dac/ad5758.c
> 
> diff --git a/MAINTAINERS b/MAINTAINERS
> index 4b65225..1993779 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -802,6 +802,13 @@ S:       Supported
>  F:   drivers/iio/dac/ad5686*
>  F:   drivers/iio/dac/ad5696*
>  
> +ANALOG DEVICES INC AD5758 DRIVER
> +M:   Stefan Popa <stefan.p...@analog.com>
> +L:   linux-...@vger.kernel.org
> +W:   http://ez.analog.com/community/linux-device-drivers
> +S:   Supported
> +F:   drivers/iio/dac/ad5758.c
> +
>  ANALOG DEVICES INC AD9389B DRIVER
>  M:   Hans Verkuil <hans.verk...@cisco.com>
>  L:   linux-me...@vger.kernel.org
> diff --git a/drivers/iio/dac/Kconfig b/drivers/iio/dac/Kconfig
> index 06e90de..80beb64 100644
> --- a/drivers/iio/dac/Kconfig
> +++ b/drivers/iio/dac/Kconfig
> @@ -167,6 +167,16 @@ config AD5755
>         To compile this driver as a module, choose M here: the
>         module will be called ad5755.
>  
> +config AD5758
> +     tristate "Analog Devices AD5758 DAC driver"
> +     depends on SPI_MASTER
> +     help
> +       Say yes here to build support for Analog Devices AD5758 single channel
> +       Digital to Analog Converter.
> +
> +       To compile this driver as a module, choose M here: the
> +       module will be called ad5758.
> +
>  config AD5761
>       tristate "Analog Devices AD5761/61R/21/21R DAC driver"
>       depends on SPI_MASTER
> diff --git a/drivers/iio/dac/Makefile b/drivers/iio/dac/Makefile
> index 57aa230..e859f2d 100644
> --- a/drivers/iio/dac/Makefile
> +++ b/drivers/iio/dac/Makefile
> @@ -16,6 +16,7 @@ obj-$(CONFIG_AD5592R_BASE) += ad5592r-base.o
>  obj-$(CONFIG_AD5592R) += ad5592r.o
>  obj-$(CONFIG_AD5593R) += ad5593r.o
>  obj-$(CONFIG_AD5755) += ad5755.o
> +obj-$(CONFIG_AD5758) += ad5758.o
>  obj-$(CONFIG_AD5761) += ad5761.o
>  obj-$(CONFIG_AD5764) += ad5764.o
>  obj-$(CONFIG_AD5791) += ad5791.o
> diff --git a/drivers/iio/dac/ad5758.c b/drivers/iio/dac/ad5758.c
> new file mode 100644
> index 0000000..0a26b9d
> --- /dev/null
> +++ b/drivers/iio/dac/ad5758.c
> @@ -0,0 +1,826 @@
> +// SPDX-License-Identifier: GPL-2.0+
> +/*
> + * AD5758 Digital to analog converters driver
> + *
> + * Copyright 2018 Analog Devices Inc.
> + */
> +
> +#include <linux/fs.h>
> +#include <linux/device.h>
> +#include <linux/module.h>
> +#include <linux/kernel.h>
> +#include <linux/slab.h>
> +#include <linux/sysfs.h>
> +#include <linux/spi/spi.h>
> +#include <linux/delay.h>
> +
> +#include <linux/iio/iio.h>
> +#include <linux/iio/sysfs.h>
> +#include <linux/property.h>
> +
> +/* AD5758 registers definition */
> +#define AD5758_NOP                                   0x00
> +#define AD5758_DAC_INPUT                             0x01
> +#define AD5758_DAC_OUTPUT                            0x02
> +#define AD5758_CLEAR_CODE                            0x03
> +#define AD5758_USER_GAIN                             0x04
> +#define AD5758_USER_OFFSET                           0x05
> +#define AD5758_DAC_CONFIG                            0x06
> +#define AD5758_SW_LDAC                                       0x07
> +#define AD5758_KEY                                   0x08
> +#define AD5758_GP_CONFIG1                            0x09
> +#define AD5758_GP_CONFIG2                            0x0A
> +#define AD5758_DCDC_CONFIG1                          0x0B
> +#define AD5758_DCDC_CONFIG2                          0x0C
> +#define AD5758_WDT_CONFIG                            0x0F
> +#define AD5758_DIGITAL_DIAG_CONFIG                   0x10
> +#define AD5758_ADC_CONFIG                            0x11
> +#define AD5758_FAULT_PIN_CONFIG                              0x12
> +#define AD5758_TWO_STAGE_READBACK_SELECT             0x13
> +#define AD5758_DIGITAL_DIAG_RESULTS                  0x14
> +#define AD5758_ANALOG_DIAG_RESULTS                   0x15
> +#define AD5758_STATUS                                        0x16
> +#define AD5758_CHIP_ID                                       0x17
> +#define AD5758_FREQ_MONITOR                          0x18
> +#define AD5758_DEVICE_ID_0                           0x19
> +#define AD5758_DEVICE_ID_1                           0x1A
> +#define AD5758_DEVICE_ID_2                           0x1B
> +#define AD5758_DEVICE_ID_3                           0x1C
> +
> +/* AD5758_DAC_CONFIG */
> +#define AD5758_DAC_CONFIG_RANGE_MSK                  GENMASK(3, 0)
> +#define AD5758_DAC_CONFIG_RANGE_MODE(x)                      (((x) & 0xF) << 
> 0)
> +#define AD5758_DAC_CONFIG_OVRNG_EN_MSK                       BIT(4)
> +#define AD5758_DAC_CONFIG_OVRNG_EN_MODE(x)           (((x) & 0x1) << 4)
> +#define AD5758_DAC_CONFIG_INT_EN_MSK                 BIT(5)
> +#define AD5758_DAC_CONFIG_INT_EN_MODE(x)             (((x) & 0x1) << 5)
> +#define AD5758_DAC_CONFIG_OUT_EN_MSK                 BIT(6)
> +#define AD5758_DAC_CONFIG_OUT_EN_MODE(x)             (((x) & 0x1) << 6)
> +#define AD5758_DAC_CONFIG_RSET_EXT_EN_MSK            BIT(7)
> +#define AD5758_DAC_CONFIG_RSET_EXT_EN_MODE(x)                (((x) & 0x1) << 
> 7)
> +#define AD5758_DAC_CONFIG_SR_EN_MSK                  BIT(8)
> +#define AD5758_DAC_CONFIG_SR_EN_MODE(x)                      (((x) & 0x1) << 
> 8)
> +#define AD5758_DAC_CONFIG_SR_CLOCK_MSK                       GENMASK(12, 9)
> +#define AD5758_DAC_CONFIG_SR_CLOCK_MODE(x)           (((x) & 0xF) << 9)
> +#define AD5758_DAC_CONFIG_SR_STEP_MSK                        GENMASK(15, 13)
> +#define AD5758_DAC_CONFIG_SR_STEP_MODE(x)            (((x) & 0x7) << 13)
> +
> +/* AD5758_KEY */
> +#define AD5758_KEY_CODE_RESET_1                              0x15FA
> +#define AD5758_KEY_CODE_RESET_2                              0xAF51
> +#define AD5758_KEY_CODE_SINGLE_ADC_CONV                      0x1ADC
> +#define AD5758_KEY_CODE_RESET_WDT                    0x0D06
> +#define AD5758_KEY_CODE_CALIB_MEM_REFRESH            0xFCBA
> +
> +/* AD5758_DCDC_CONFIG1 */
> +#define AD5758_DCDC_CONFIG1_DCDC_VPROG_MSK           GENMASK(4, 0)
> +#define AD5758_DCDC_CONFIG1_DCDC_VPROG_MODE(x)               (((x) & 0x1F) 
> << 0)
> +#define AD5758_DCDC_CONFIG1_DCDC_MODE_MSK            GENMASK(6, 5)
> +#define AD5758_DCDC_CONFIG1_DCDC_MODE_MODE(x)                (((x) & 0x3) << 
> 5)
> +#define AD5758_DCDC_CONFIG1_FAULT_PROT_SW_EN_MSK     BIT(7)
> +#define AD5758_DCDC_CONFIG1_FAULT_PROT_SW_EN_MODE(x) (((x) & 0x1) << 7)
> +
> +/* AD5758_DCDC_CONFIG2 */
> +#define AD5758_DCDC_CONFIG2_ILIMIT_MSK                       GENMASK(3, 1)
> +#define AD5758_DCDC_CONFIG2_ILIMIT_MODE(x)           (((x) & 0x7) << 1)
> +#define AD5758_DCDC_CONFIG2_ADC_CONTROL_DIAG_MSK     GENMASK(5, 4)
> +#define AD5758_DCDC_CONFIG2_ADC_CONTROL_DIAG_MODE(x) (((x) & 0x3) << 4)
> +#define AD5758_DCDC_CONFIG2_VIOUT_PULLDOWN_EN_MSK    BIT(6)
> +#define AD5758_DCDC_CONFIG2_VIOUT_PULLDOWN_EN_MODE(x)        (((x) & 0x1) << 
> 6)
> +#define AD5758_DCDC_CONFIG2_SHORT_DEGLITCH_MSK               BIT(7)
> +#define AD5758_DCDC_CONFIG2_SHORT_DEGLITCH_MODE(x)   (((x) & 0x1) << 7)
> +#define AD5758_DCDC_CONFIG2_READ_COMP_DIS_MSK                BIT(10)
> +#define AD5758_DCDC_CONFIG2_READ_COMP_DIS_MODE(x)    (((x) & 0x1) << 10)
> +#define AD5758_DCDC_CONFIG2_INTR_SAT_3WI_MSK         BIT(11)
> +#define AD5758_DCDC_CONFIG2_BUSY_3WI_MSK             BIT(12)
> +
> +/* AD5758_DIGITAL_DIAG_RESULTS */
> +#define AD5758_DIG_DIAG_RES_CAL_MEM_UNREFRESHED_MSK  BIT(15)
> +
> +#define AD5758_REG_WRITE(x)  ((0x80) | ((x) & 0x1F))

parenthesis around 0x80 not strictly needed

> +
> +/* x^8 + x^2 + x^1 + x^0 */
> +#define AD5758_CRC8_POLY     0x07
> +
> +/**
> + * struct ad5758_state - driver instance specific data
> + * @spi:     spi_device
> + * @dc_dc_mode:      variable which stores the mode of operation

the documentation misses several fields

> + * @out_range:       variable which stores the output range
> + * @pwr_down:        variable which contains whether a channel is powered 
> down or not

sounds like it should be bool?

> + * @data:    spi transfer buffers
> + */
> +
> +struct ad5758_state {
> +     struct spi_device *spi;
> +     struct mutex lock;
> +     unsigned int dc_dc_mode;
> +     unsigned int dc_dc_ilim;
> +     unsigned int sr_config[3];
> +     unsigned int out_range;
> +     unsigned int pwr_down;
> +
> +     /*
> +      * DMA (thus cache coherency maintenance) requires the
> +      * transfer buffers to live in their own cache lines.
> +      */
> +
> +     union {
> +             __be32 d32;
> +             u8 d8[4];
> +     } data[3] ____cacheline_aligned;
> +};
> +
> +enum ad5758_output_range {
> +     AD5758_RANGE_0V_5V,
> +     AD5758_RANGE_0V_10V,
> +     AD5758_RANGE_PLUSMINUS_5V,
> +     AD5758_RANGE_PLUSMINUS_10V,
> +     AD5758_RANGE_0mA_20mA = 8,
> +     AD5758_RANGE_0mA_24mA,
> +     AD5758_RANGE_4mA_24mA,
> +     AD5758_RANGE_PLUSMINUS_20mA,
> +     AD5758_RANGE_PLUSMINUS_24mA,
> +     AD5758_RANGE_MINUS_1mA_PLUS_22mA,
> +};
> +
> +enum ad5758_dc_dc_mode {
> +     AD5758_DCDC_MODE_POWER_OFF,
> +     AD5758_DCDC_MODE_DPC_CURRENT,
> +     AD5758_DCDC_MODE_DPC_VOLTAGE,
> +     AD5758_DCDC_MODE_PPC_CURRENT,
> +};
> +
> +struct ad5758_range {
> +     int reg;
> +     int min;
> +     int max;
> +};
> +
> +static const struct ad5758_range ad5758_min_max_table[] = {
> +     { AD5758_RANGE_0V_5V, 0, 5000 },
> +     { AD5758_RANGE_0V_10V, 0, 10000 },
> +     { AD5758_RANGE_PLUSMINUS_5V, -5000, 5000 },
> +     { AD5758_RANGE_PLUSMINUS_10V, -10000, 10000 },
> +     { AD5758_RANGE_0mA_20mA, 0, 20},
> +     { AD5758_RANGE_0mA_24mA, 0, 24 },
> +     { AD5758_RANGE_4mA_24mA, 4, 24 },
> +     { AD5758_RANGE_PLUSMINUS_20mA, -20, 20 },
> +     { AD5758_RANGE_PLUSMINUS_24mA, -24, 24 },
> +     { AD5758_RANGE_MINUS_1mA_PLUS_22mA, -1, 22 },
> +};
> +
> +static const int ad5758_slew_rate_clk[16] = {
> +     240000, 200000, 150000, 128000, 64000, 32000, 16000, 8000, 4000, 2000,
> +     1000, 512, 256, 128, 64, 16
> +};
> +
> +static const int ad5758_slew_rate_step[8] = {
> +     4, 12, 64, 120, 256, 500, 1820, 2048
> +};
> +
> +static const int ad5758_dc_dc_ilimt[6] = {

maybe ad5758_dc_dc_ilim? consistent with the attribute in ad5758_state 
(dc_dc_ilim)

> +     150, 200, 250, 300, 350, 400
> +};
> +
> +static int ad5758_spi_reg_read(struct ad5758_state *st, unsigned int addr)
> +{
> +     struct spi_transfer t[] = {
> +             {
> +                     .tx_buf = &st->data[0].d8[0],
> +                     .len = 4,
> +                     .cs_change = 1,
> +             }, {
> +                     .tx_buf = &st->data[1].d8[0],
> +                     .rx_buf = &st->data[2].d8[0],
> +                     .len = 4,
> +             },
> +     };
> +     int ret;
> +
> +     st->data[0].d32 = cpu_to_be32(
> +             (AD5758_REG_WRITE(AD5758_TWO_STAGE_READBACK_SELECT) << 24) |
> +             (addr << 8));
> +     st->data[1].d32 = cpu_to_be32(AD5758_REG_WRITE(AD5758_NOP) << 24);
> +
> +     ret = spi_sync_transfer(st->spi, t, ARRAY_SIZE(t));
> +     if (ret < 0)
> +             return ret;
> +
> +     return (be32_to_cpu(st->data[2].d32) >> 8) & 0xFFFF;
> +}
> +
> +static int ad5758_spi_reg_write(struct ad5758_state *st,
> +                             unsigned int addr,
> +                             unsigned int val)
> +{
> +     st->data[0].d32 = cpu_to_be32((AD5758_REG_WRITE(addr) << 24) |
> +                                   ((val & 0xFFFF) << 8));
> +
> +     return spi_write(st->spi, &st->data[0].d8[0], 4);

wouldn't it be clearer to write
return spi_write(st->spi, &st->data[0].d32, sizeof(st->data[0].d32));

> +}
> +
> +static int ad5758_spi_write_mask(struct ad5758_state *st,
> +                              unsigned int addr,
> +                              unsigned long int mask,
> +                              unsigned int val)
> +{
> +     int regval;
> +
> +     regval = ad5758_spi_reg_read(st, addr);
> +     if (regval < 0)
> +             return regval;
> +
> +     regval &= ~mask;
> +     regval |= val;
> +
> +     return ad5758_spi_reg_write(st, addr, regval);
> +}
> +
> +static int ad5758_get_array_index(const int *array, unsigned int size, int 
> val)
> +{
> +     int i;
> +
> +     for (i = 0; i < size; i++) {
> +             if (val == array[i])
> +                     return i;
> +     }
> +
> +     return -EINVAL;
> +}
> +
> +static int ad5758_wait_for_task_complete(struct ad5758_state *st,
> +                                      unsigned int reg,
> +                                      unsigned int mask)
> +{
> +     unsigned int timeout;
> +     int ret;
> +
> +     timeout = 4;
> +     do {
> +             ret = ad5758_spi_reg_read(st, reg);
> +             if (ret < 0)
> +                     return ret;
> +
> +             if (!(ret & mask))
> +                     return 0;
> +
> +             mdelay(1);
> +     } while (--timeout);
> +
> +     dev_err(&st->spi->dev,
> +             "Error reading bit 0x%x in 0x%x register\n", mask, reg);
> +
> +     return -EIO;
> +}
> +
> +static int ad5758_calib_mem_refresh(struct ad5758_state *st)
> +{
> +     int ret;
> +
> +     ret = ad5758_spi_reg_write(st, AD5758_KEY,
> +                                AD5758_KEY_CODE_CALIB_MEM_REFRESH);
> +
no newline here

> +     if (ret < 0) {
> +             dev_err(&st->spi->dev,
> +                     "Failed to initiate a calibration memory refresh\n");
> +             return ret;
> +     }
> +
> +     /* Wait to allow time for the internal calibrations to complete */
> +     return ad5758_wait_for_task_complete(st, AD5758_DIGITAL_DIAG_RESULTS,
> +                             AD5758_DIG_DIAG_RES_CAL_MEM_UNREFRESHED_MSK);
> +}
> +
> +static int ad5758_soft_reset(struct ad5758_state *st)
> +{
> +     int ret;
> +
> +     ret = ad5758_spi_reg_write(st, AD5758_KEY, AD5758_KEY_CODE_RESET_1);
> +     if (ret < 0)
> +             return ret;
> +
> +     ret = ad5758_spi_reg_write(st, AD5758_KEY, AD5758_KEY_CODE_RESET_2);
> +
> +     mdelay(1);
> +
> +     return ret;
> +}
> +
> +static int ad5758_set_dc_dc_conv_mode(struct ad5758_state *st,
> +                                   unsigned int mode)

mode is more like u8?

or can the enum ad5758_dc_dc_mode be used here?

> +{
> +     int ret;
> +
> +     ret = ad5758_spi_write_mask(st, AD5758_DCDC_CONFIG1,
> +                                 AD5758_DCDC_CONFIG1_DCDC_MODE_MSK,
> +                                 AD5758_DCDC_CONFIG1_DCDC_MODE_MODE(mode));
> +     if (ret < 0)
> +             return ret;
> +
> +     /*
> +      * Poll the BUSY_3WI bit in the DCDC_CONFIG2 register until it is 0.
> +      * This allows the 3-wire interface communication to complete.
> +      */
> +     ret = ad5758_wait_for_task_complete(st, AD5758_DCDC_CONFIG2,
> +                                         AD5758_DCDC_CONFIG2_BUSY_3WI_MSK);
> +     if (ret < 0)
> +             return ret;

maybe a helper function that combines spi_write_mask() and 
wait_for_task_complete()?

> +
> +     st->dc_dc_mode = mode;
> +
> +     return ret;
> +}
> +
> +static int ad5758_set_dc_dc_ilim(struct ad5758_state *st, unsigned int ilim)
> +{
> +     int ret;
> +
> +     ret = ad5758_spi_write_mask(st, AD5758_DCDC_CONFIG2,
> +                                 AD5758_DCDC_CONFIG2_ILIMIT_MSK,
> +                                 AD5758_DCDC_CONFIG2_ILIMIT_MODE(ilim));
> +     if (ret < 0)
> +             return ret;
> +     /*
> +      * Poll the BUSY_3WI bit in the DCDC_CONFIG2 register until it is 0.
> +      * This allows the 3-wire interface communication to complete.
> +      */
> +     return ad5758_wait_for_task_complete(st, AD5758_DCDC_CONFIG2,
> +                                          AD5758_DCDC_CONFIG2_BUSY_3WI_MSK);
> +}
> +
> +static int ad5758_slew_rate_config(struct ad5758_state *st,
> +                                unsigned int enable,
> +                                unsigned int sr_clk,
> +                                unsigned int sr_step)
> +{
> +     unsigned int mode;
> +     unsigned long int mask;
> +     int ret;
> +
> +     mask = (AD5758_DAC_CONFIG_SR_EN_MSK |
> +            AD5758_DAC_CONFIG_SR_CLOCK_MSK |
> +            AD5758_DAC_CONFIG_SR_STEP_MSK);

parenthesis not needed

> +
> +     mode = (AD5758_DAC_CONFIG_SR_EN_MODE(enable) |
> +             AD5758_DAC_CONFIG_SR_CLOCK_MODE(sr_clk) |
> +             AD5758_DAC_CONFIG_SR_STEP_MODE(sr_step));

parenthesis not needed

> +
> +     ret = ad5758_spi_write_mask(st, AD5758_DAC_CONFIG, mask, mode);
> +     if (ret < 0)
> +             return ret;
> +
> +     /* Wait to allow time for the internal calibrations to complete */
> +     return ad5758_wait_for_task_complete(st, AD5758_DIGITAL_DIAG_RESULTS,
> +                             AD5758_DIG_DIAG_RES_CAL_MEM_UNREFRESHED_MSK);
> +}
> +
> +static int ad5758_set_out_range(struct ad5758_state *st, unsigned int range)
> +{
> +     int ret;
> +
> +     ret = ad5758_spi_write_mask(st, AD5758_DAC_CONFIG,
> +                                 AD5758_DAC_CONFIG_RANGE_MSK,
> +                                 AD5758_DAC_CONFIG_RANGE_MODE(
> +                                         ad5758_min_max_table[range].reg));
> +     if (ret < 0)
> +             return ret;
> +
> +     /* Wait to allow time for the internal calibrations to complete */
> +     ret =  ad5758_wait_for_task_complete(st, AD5758_DIGITAL_DIAG_RESULTS,
> +                             AD5758_DIG_DIAG_RES_CAL_MEM_UNREFRESHED_MSK);
> +     if (ret < 0)
> +             return ret;
> +
> +     st->out_range = range;
> +
> +     return ret;
> +}
> +
> +static int ad5758_fault_prot_switch_en(struct ad5758_state *st,
> +                                    unsigned char enable)

enable could be bool?

> +{
> +     int ret;
> +
> +     ret = ad5758_spi_write_mask(st, AD5758_DCDC_CONFIG1,
> +                     AD5758_DCDC_CONFIG1_FAULT_PROT_SW_EN_MSK,
> +                     AD5758_DCDC_CONFIG1_FAULT_PROT_SW_EN_MODE(enable));
> +     if (ret < 0)
> +             return ret;
> +     /*
> +      * Poll the BUSY_3WI bit in the DCDC_CONFIG2 register until it is 0.
> +      * This allows the 3-wire interface communication to complete.
> +      */
> +     return ad5758_wait_for_task_complete(st, AD5758_DCDC_CONFIG2,
> +                                          AD5758_DCDC_CONFIG2_BUSY_3WI_MSK);
> +}
> +
> +static int ad5758_internal_buffers_en(struct ad5758_state *st,
> +                                   unsigned char enable)

enable could be bool?

> +{
> +     int ret;
> +
> +     ret = ad5758_spi_write_mask(st, AD5758_DAC_CONFIG,
> +                                 AD5758_DAC_CONFIG_INT_EN_MSK,
> +                                 AD5758_DAC_CONFIG_INT_EN_MODE(enable));
> +     if (ret < 0)
> +             return ret;
> +
> +     /* Wait to allow time for the internal calibrations to complete */
> +     return ad5758_wait_for_task_complete(st, AD5758_DIGITAL_DIAG_RESULTS,
> +                             AD5758_DIG_DIAG_RES_CAL_MEM_UNREFRESHED_MSK);
> +}
> +
> +static int ad5758_reg_access(struct iio_dev *indio_dev,
> +                          unsigned int reg,
> +                          unsigned int writeval,
> +                          unsigned int *readval)
> +{
> +     struct ad5758_state *st = iio_priv(indio_dev);
> +     int ret;
> +
> +     mutex_lock(&st->lock);
> +     if (readval == NULL) {
> +             ret =  ad5758_spi_reg_write(st, reg, writeval);
> +     } else {
> +             ret = ad5758_spi_reg_read(st, reg);
> +             if (ret < 0)

mutex_unlock()?

> +                     return ret;
> +
> +             *readval = ret;
> +             ret = 0;
> +     }
> +     mutex_unlock(&st->lock);
> +
> +     return ret;
> +}
> +
> +static int ad5758_read_raw(struct iio_dev *indio_dev,
> +                        struct iio_chan_spec const *chan,
> +                        int *val, int *val2, long info)
> +{
> +     struct ad5758_state *st = iio_priv(indio_dev);
> +     int max, min, ret;
> +
> +     switch (info) {
> +     case IIO_CHAN_INFO_RAW:
> +             mutex_lock(&st->lock);
> +             ret = ad5758_spi_reg_read(st, AD5758_DAC_INPUT);

could move the mutex_unlock() to here?

> +             if (ret < 0) {
> +                     mutex_unlock(&st->lock);
> +                     return ret;
> +             }
> +
> +             *val = ret;
> +             mutex_unlock(&st->lock);
> +             return IIO_VAL_INT;
> +     case IIO_CHAN_INFO_SCALE:
> +             min = ad5758_min_max_table[st->out_range].min;
> +             max = ad5758_min_max_table[st->out_range].max;
> +             *val = max - min;
> +             *val2 = chan->scan_type.realbits;
> +             return IIO_VAL_FRACTIONAL_LOG2;
> +     default:
> +             return -EINVAL;
> +     }
> +

not reachable

> +     return -EINVAL;
> +}
> +
> +static int ad5758_write_raw(struct iio_dev *indio_dev,
> +                         struct iio_chan_spec const *chan,
> +                         int val, int val2, long info)
> +{
> +     struct ad5758_state *st = iio_priv(indio_dev);
> +     int ret;
> +
> +     switch (info) {
> +     case IIO_CHAN_INFO_RAW:
> +             mutex_lock(&st->lock);
> +             ret = ad5758_spi_reg_write(st, AD5758_DAC_INPUT, val);
> +             mutex_unlock(&st->lock);

return directly

> +             break;
> +     default:
> +             ret = -EINVAL;
> +             break;

return directly

> +     }
> +
> +     return ret;
> +}
> +
> +static ssize_t ad5758_read_powerdown(struct iio_dev *indio_dev,
> +                                  uintptr_t priv,
> +                                  const struct iio_chan_spec *chan,
> +                                  char *buf)
> +{
> +     struct ad5758_state *st = iio_priv(indio_dev);
> +
> +     return sprintf(buf, "%d\n", st->pwr_down);
> +}
> +
> +static ssize_t ad5758_write_powerdown(struct iio_dev *indio_dev,
> +                                   uintptr_t priv,
> +                                   struct iio_chan_spec const *chan,
> +                                   const char *buf, size_t len)
> +{
> +     struct ad5758_state *st = iio_priv(indio_dev);
> +     bool pwr_down;
> +     unsigned int dcdc_config1_mode, dc_dc_mode, dac_config_mode, val;
> +     unsigned long int dcdc_config1_msk, dac_config_msk;
> +     int ret;
> +
> +     ret = strtobool(buf, &pwr_down);
> +     if (ret)
> +             return ret;
> +
> +     mutex_lock(&st->lock);
> +     if (pwr_down) {
> +             dc_dc_mode = AD5758_DCDC_MODE_POWER_OFF;
> +             val = 0;
> +     } else {
> +             dc_dc_mode = st->dc_dc_mode;
> +             val = 1;
> +     }
> +
> +     dcdc_config1_mode = (AD5758_DCDC_CONFIG1_DCDC_MODE_MODE(dc_dc_mode) |
> +                          AD5758_DCDC_CONFIG1_FAULT_PROT_SW_EN_MODE(val));
> +     dcdc_config1_msk = (AD5758_DCDC_CONFIG1_DCDC_MODE_MSK |
> +                         AD5758_DCDC_CONFIG1_FAULT_PROT_SW_EN_MSK);
> +
> +     ret = ad5758_spi_write_mask(st, AD5758_DCDC_CONFIG1,
> +                                 dcdc_config1_msk,
> +                                 dcdc_config1_mode);
> +     if (ret < 0)
> +             goto err_unlock;
> +
> +     dac_config_mode = (AD5758_DAC_CONFIG_OUT_EN_MODE(val) |
> +                        AD5758_DAC_CONFIG_INT_EN_MODE(val));
> +     dac_config_msk =  (AD5758_DAC_CONFIG_OUT_EN_MSK |
> +                        AD5758_DAC_CONFIG_INT_EN_MSK);
> +
> +     ret = ad5758_spi_write_mask(st, AD5758_DAC_CONFIG,
> +                                 dac_config_msk,
> +                                 dac_config_mode);
> +     if (ret < 0)
> +             goto err_unlock;
> +
> +     st->pwr_down = pwr_down;
> +
> +err_unlock:
> +     mutex_unlock(&st->lock);
> +
> +     return ret ? ret : len;
> +}
> +
> +static const struct iio_info ad5758_info = {
> +     .read_raw = ad5758_read_raw,
> +     .write_raw = ad5758_write_raw,
> +     .debugfs_reg_access = &ad5758_reg_access,
> +};
> +
> +static const struct iio_chan_spec_ext_info ad5758_ext_info[] = {
> +     {
> +             .name = "powerdown",
> +             .read = ad5758_read_powerdown,
> +             .write = ad5758_write_powerdown,
> +             .shared = IIO_SEPARATE,
> +     },
> +     { },
> +};
> +
> +static const struct iio_chan_spec ad5758_channels[] = {
> +     {
> +             .type = IIO_VOLTAGE,
> +             .info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
> +             .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),
> +             .indexed = 1,
> +             .output = 1,
> +             .channel = 0,

no need for .channel = 0

> +             .scan_index = 0,

buffered mode not supported, hence no .scan_type, .scan_index necessary

> +             .scan_type = {
> +                     .sign = 'u',
> +                     .realbits = 16,
> +                     .storagebits = 32,
> +                     .shift = 0,
> +                     .endianness = IIO_BE,
> +             },
> +             .ext_info = ad5758_ext_info,
> +     },
> +};
> +
> +static int ad5758_crc_disable(struct ad5758_state *st)
> +{
> +     st->data[0].d32 =
> +             cpu_to_be32(
> +             (AD5758_REG_WRITE(AD5758_DIGITAL_DIAG_CONFIG) << 24) | 0x5C3A);
> +
> +     return spi_write(st->spi, &st->data[0].d8[0], 4);
> +}
> +
> +static void ad5758_parse_dt(struct ad5758_state *st)
> +{
> +     unsigned int i, tmp, tmparray[3];
> +     int index;
> +
> +     st->dc_dc_ilim = 150;
> +     if (!device_property_read_u32(&st->spi->dev,
> +                                   "adi,dc-dc-ilim", &tmp)) {
> +             index = ad5758_get_array_index(ad5758_dc_dc_ilimt,
> +                                     ARRAY_SIZE(ad5758_dc_dc_ilimt), tmp);
> +             if (index < 0)
> +                     dev_warn(&st->spi->dev,
> +                              "dc-dc-ilim out of range using default");

a comma after range, i.e. "dc-dc-ilim out of range, using default", maybe 
even state what the default is

\n missing

> +             else
> +                     st->dc_dc_ilim = index;
> +     } else {
> +             dev_dbg(&st->spi->dev,
> +                      "Missing \"dc-dc-ilim\" property, using default\n");
> +     }
> +
> +     st->dc_dc_mode = AD5758_DCDC_MODE_DPC_VOLTAGE;
> +     if (device_property_read_u32(&st->spi->dev, "adi,dc-dc-mode",
> +                                  &st->dc_dc_mode))
> +             dev_dbg(&st->spi->dev,
> +                     "Missing \"dc-dc-mode\" property, using DPC_VOLTAGE\n");
> +
> +     /* 0 V to 5 V voltage range */
> +     st->out_range = 0;
> +     if (!device_property_read_u32(&st->spi->dev, "adi,range", &tmp)) {
> +             for (i = 0; i < ARRAY_SIZE(ad5758_min_max_table); i++) {
> +                     if (tmp == ad5758_min_max_table[i].reg) {
> +                             st->out_range = i;
> +                             break;
> +                     }
> +             }
> +
> +             if (i == ARRAY_SIZE(ad5758_min_max_table))
> +                     dev_warn(&st->spi->dev, "range invalid, using default");

\n missing

> +     } else {
> +             dev_dbg(&st->spi->dev,
> +                     "Missing \"range\" property, using default\n");
> +     }
> +
> +     st->sr_config[0] = 1;
> +     st->sr_config[1] = 16000;
> +     st->sr_config[2] = 4;
> +     if (!device_property_read_u32_array(&st->spi->dev, "adi,slew",
> +                                         tmparray, 3)) {
> +             st->sr_config[0] = tmparray[0];
> +
> +             index = ad5758_get_array_index(ad5758_slew_rate_clk,
> +                                            ARRAY_SIZE(ad5758_slew_rate_clk),
> +                                            tmparray[1]);
> +
> +             if (index < 0)
> +                     dev_warn(&st->spi->dev,
> +                             "slew rate clock out of range, using default");

\n missing

> +             else
> +                     st->sr_config[1] = index;
> +
> +             index = ad5758_get_array_index(ad5758_slew_rate_step,
> +                                     ARRAY_SIZE(ad5758_slew_rate_step),
> +                                     tmparray[2]);
> +
> +             if (index < 0)
> +                     dev_warn(&st->spi->dev,
> +                             "slew rate step out of range, using default");

\n missing

> +             else
> +                     st->sr_config[2] = index;
> +     } else {
> +             dev_dbg(&st->spi->dev,
> +                      "Missing \"slew\" property, using default\n");
> +     }
> +}
> +
> +static int ad5758_init(struct ad5758_state *st)
> +{
> +     int regval, ret;
> +
> +     ad5758_parse_dt(st);
> +
> +     /* Disable CRC checks */
> +     ret = ad5758_crc_disable(st);
> +     if (ret < 0)
> +             return ret;
> +
> +     /* Perform a software reset */
> +     ret = ad5758_soft_reset(st);
> +     if (ret < 0)
> +             return ret;
> +
> +     /* Disable CRC checks */
> +     ret = ad5758_crc_disable(st);
> +     if (ret < 0)
> +             return ret;
> +
> +     /* Perform a calibration memory refresh */
> +     ret = ad5758_calib_mem_refresh(st);
> +     if (ret < 0)
> +             return ret;
> +
> +     regval = ad5758_spi_reg_read(st, AD5758_DIGITAL_DIAG_RESULTS);
> +     if (regval < 0)
> +             return regval;
> +
> +     /* Clear all the error flags */
> +     ret = ad5758_spi_reg_write(st, AD5758_DIGITAL_DIAG_RESULTS, regval);
> +     if (ret < 0)
> +             return ret;
> +
> +     /* Set the dc-to-dc current limit */
> +     ret = ad5758_set_dc_dc_ilim(st, st->dc_dc_ilim);
> +     if (ret < 0)
> +             return ret;
> +
> +     /* Configure the dc-to-dc controller mode */
> +     ret = ad5758_set_dc_dc_conv_mode(st, st->dc_dc_mode);
> +     if (ret < 0)
> +             return ret;
> +
> +     /* Configure the output range */
> +     ret = ad5758_set_out_range(st, st->out_range);
> +     if (ret < 0)
> +             return ret;
> +
> +     /* Enable Slew Rate Control, set the slew rate clock and step */
> +     ret = ad5758_slew_rate_config(st, st->sr_config[0],
> +                                   st->sr_config[1], st->sr_config[2]);
> +     if (ret < 0)
> +             return ret;
> +
> +     /* Enable the VIOUT fault protection switch (FPS is closed) */
> +     ret = ad5758_fault_prot_switch_en(st, 1);
> +     if (ret < 0)
> +             return ret;
> +
> +     /* Power up the DAC and internal (INT) amplifiers */
> +     ret = ad5758_internal_buffers_en(st, 1);
> +     if (ret < 0)
> +             return ret;
> +
> +     /* Enable VIOUT */
> +     ret = ad5758_spi_write_mask(st, AD5758_DAC_CONFIG,
> +                                 AD5758_DAC_CONFIG_OUT_EN_MSK,
> +                                 AD5758_DAC_CONFIG_OUT_EN_MODE(1));

return directly, i.e.
return ad5758_spi...

> +
> +     return ret;
> +}
> +
> +static int ad5758_probe(struct spi_device *spi)
> +{
> +     struct ad5758_state *st;
> +     struct iio_dev *indio_dev;
> +     int ret;
> +
> +     indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*st));
> +     if (!indio_dev)
> +             return -ENOMEM;
> +
> +     st = iio_priv(indio_dev);
> +     spi_set_drvdata(spi, indio_dev);
> +
> +     st->spi = spi;
> +
> +     indio_dev->dev.parent = &spi->dev;
> +     indio_dev->name = spi_get_device_id(spi)->name;
> +     indio_dev->info = &ad5758_info;
> +     indio_dev->modes = INDIO_DIRECT_MODE;
> +     indio_dev->channels = ad5758_channels;
> +     indio_dev->num_channels = ARRAY_SIZE(ad5758_channels);
> +
> +     mutex_init(&st->lock);
> +
> +     ret = ad5758_init(st);
> +     if (ret < 0) {
> +             dev_err(&spi->dev, "AD5758 init failed\n");
> +             return ret;
> +     }
> +
> +     ret = iio_device_register(indio_dev);
> +     if (ret) {
> +             dev_err(&spi->dev, "Failed to register iio device\n");

is the message really necessary/likely?

> +             return ret;
> +     }
> +
> +     return 0;
> +}
> +
> +static const struct spi_device_id ad5758_id[] = {
> +     { "ad5758", 0 },
> +     {}
> +};
> +MODULE_DEVICE_TABLE(spi, ad5758_id);
> +
> +static struct spi_driver ad5758_driver = {
> +     .driver = {
> +             .name = KBUILD_MODNAME,
> +     },
> +     .probe = ad5758_probe,
> +     .id_table = ad5758_id,
> +};
> +
> +module_spi_driver(ad5758_driver);
> +
> +MODULE_AUTHOR("Stefan Popa <stefan.p...@analog.com>");
> +MODULE_DESCRIPTION("Analog Devices AD5758 DAC");
> +MODULE_LICENSE("GPL v2");
> 

-- 

Peter Meerwald-Stadler
Mobile: +43 664 24 44 418

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