On Wed, 4 Jul 2018 17:32:03 +0300
Stefan Popa <stefan.p...@analog.com> wrote:

> 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.
> 
> Datasheet:
> http://www.analog.com/media/en/technical-documentation/data-sheets/ad5758.pdf
> 
> Signed-off-by: Stefan Popa <stefan.p...@analog.com>

Very nice!

Applied to the togreg branch of iio.git and pushed out as testing for the
autobuilders to play with it.

Thanks,

Jonathan

> ---
> Changes in v5:
>       - changed the handling choice of voltage vs current by picking
>         between two constant structs.
>       - returned ad5758_wait_for_task_complete() directly where possible.
>       - fixed double spaces and removed unnecessary parentheses.
>       - kept the includes in alphabetical order and removed asm/div64.h.
>       - used usleep_range() instead of udelay().
>       - removed unnecessary casting when calling bsearch().
> Changes in v4:
>       - fixed kbuild test robot warnings.
> Changes in v3:
>       - AD5758 can be both a current and voltage output DAC. The
>         decision is made based on the DT and the channel type is set
>         during probe.
>       - dc-dc-mode, range-microvolt and range-microamp are required
>         properties.
>       - Introduced a slew-time-us property from which slew rate clock
>         and slew rate step are calculated using a best match algorithm.
>       - Dropped the union from ad5758_state struct.
>       - Introduced a IIO_CHAN_INFO_OFFSET case part of ad5758_read_raw().
>       - Added a TODO comment which specifies that CRC is not supported.
>       - Kept the includes in order and removed the unused ones.
>       - Removed unused macros and shortened the lengthy ones.
>       - Renamed AD5758_REG_WRITE to AD5758_WR_FLAG_MSK.
>       - Added an explanation for enum ad5758_output_range.
>       - Used bsearch() instead of ad5758_get_array_index().
>       - Reduced the delays.
>       - strtobool() -> kstrtobool().
> 
> Changes in v2:
>       - removed unnecessary parenthesis in AD5758_REG_WRITE macro.
>       - added missing documentation fields of ad5758_state struct.
>       - changed the type of pwr_down attribute to bool.
>       - changed ad5758_dc_dc_ilimt[] to ad5758_dc_dc_ilim[].
>       - ad5758_spi_reg_write() now returns spi_write(st->spi,
>         &st->data[0].d32, sizeof(st->data[0].d32));
>       - removed unnecessary new line in ad5758_calib_mem_refresh().
>       - changed the type of the mode parameter in
>         ad5758_set_dc_dc_conv_mode() from unsigned int to enum
>         ad5758_dc_dc_mode.
>       - removed unnecessary parenthesis in ad5758_slew_rate_config().
>       - changed the type of the enable parameter in
>         ad5758_fault_prot_switch_en() from unsigned char to bool.
>       - the same as above, but for ad5758_internal_buffers_en().
>       - added a missing mutex_unlock() in ad5758_reg_access().
>       - moved the mutex_unlock() in ad5758_read_raw() and removed the
>         unreachable return.
>       - returned directly where it was possible in ad5758_write_raw().
>       - removed the channel, scan_type and scan_index fields.
>       - in ad5758_parse_dt(), added missing "\n", and specified what the
>         default mode actually is.
>       - returned directly at the end of ad5758_init().
>       - in ad5758_probe() used device managed for registering the device
>         and returned directly without the error message.
> 
>  MAINTAINERS              |   7 +
>  drivers/iio/dac/Kconfig  |  10 +
>  drivers/iio/dac/Makefile |   1 +
>  drivers/iio/dac/ad5758.c | 897 
> +++++++++++++++++++++++++++++++++++++++++++++++
>  4 files changed, 915 insertions(+)
>  create mode 100644 drivers/iio/dac/ad5758.c
> 
> diff --git a/MAINTAINERS b/MAINTAINERS
> index 00e9670..12d102d 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -796,6 +796,13 @@ M:       Michael Hanselmann <linux-ker...@hansmi.ch>
>  S:   Supported
>  F:   drivers/macintosh/ams/
>  
> +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 AD5686 DRIVER
>  M:   Stefan Popa <stefan.p...@analog.com>
>  L:   linux...@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..a1b37cf 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-$(CONFIG_AD5755) += ad5758.o
>  obj-$(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..bd36333
> --- /dev/null
> +++ b/drivers/iio/dac/ad5758.c
> @@ -0,0 +1,897 @@
> +// SPDX-License-Identifier: GPL-2.0+
> +/*
> + * AD5758 Digital to analog converters driver
> + *
> + * Copyright 2018 Analog Devices Inc.
> + *
> + * TODO: Currently CRC is not supported in this driver
> + */
> +#include <linux/bsearch.h>
> +#include <linux/delay.h>
> +#include <linux/kernel.h>
> +#include <linux/module.h>
> +#include <linux/property.h>
> +#include <linux/spi/spi.h>
> +
> +#include <linux/iio/iio.h>
> +#include <linux/iio/sysfs.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_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_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_PROT_SW_EN_MSK   BIT(7)
> +#define AD5758_DCDC_CONFIG1_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_INTR_SAT_3WI_MSK BIT(11)
> +#define AD5758_DCDC_CONFIG2_BUSY_3WI_MSK     BIT(12)
> +
> +/* AD5758_DIGITAL_DIAG_RESULTS */
> +#define AD5758_CAL_MEM_UNREFRESHED_MSK               BIT(15)
> +
> +#define AD5758_WR_FLAG_MSK(x)                (0x80 | ((x) & 0x1F))
> +
> +#define AD5758_FULL_SCALE_MICRO      65535000000ULL
> +
> +/**
> + * struct ad5758_state - driver instance specific data
> + * @spi:     spi_device
> + * @lock:    mutex lock
> + * @out_range:       struct which stores the output range
> + * @dc_dc_mode:      variable which stores the mode of operation
> + * @dc_dc_ilim:      variable which stores the dc-to-dc converter current 
> limit
> + * @slew_time:       variable which stores the target slew time
> + * @pwr_down:        variable which contains whether a channel is powered 
> down or not
> + * @data:    spi transfer buffers
> + */
> +
> +struct ad5758_range {
> +     int reg;
> +     int min;
> +     int max;
> +};
> +
> +struct ad5758_state {
> +     struct spi_device *spi;
> +     struct mutex lock;
> +     struct ad5758_range out_range;
> +     unsigned int dc_dc_mode;
> +     unsigned int dc_dc_ilim;
> +     unsigned int slew_time;
> +     bool pwr_down;
> +     __be32 d32[3];
> +};
> +
> +/**
> + * Output ranges corresponding to bits [3:0] from DAC_CONFIG register
> + * 0000: 0 V to 5 V voltage range
> + * 0001: 0 V to 10 V voltage range
> + * 0010: ±5 V voltage range
> + * 0011: ±10 V voltage range
> + * 1000: 0 mA to 20 mA current range
> + * 1001: 0 mA to 24 mA current range
> + * 1010: 4 mA to 20 mA current range
> + * 1011: ±20 mA current range
> + * 1100: ±24 mA current range
> + * 1101: -1 mA to +22 mA current range
> + */
> +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,
> +};
> +
> +static const struct ad5758_range ad5758_voltage_range[] = {
> +     { AD5758_RANGE_0V_5V, 0, 5000000 },
> +     { AD5758_RANGE_0V_10V, 0, 10000000 },
> +     { AD5758_RANGE_PLUSMINUS_5V, -5000000, 5000000 },
> +     { AD5758_RANGE_PLUSMINUS_10V, -10000000, 10000000 }
> +};
> +
> +static const struct ad5758_range ad5758_current_range[] = {
> +     { AD5758_RANGE_0mA_20mA, 0, 20000},
> +     { AD5758_RANGE_0mA_24mA, 0, 24000 },
> +     { AD5758_RANGE_4mA_24mA, 4, 24000 },
> +     { AD5758_RANGE_PLUSMINUS_20mA, -20000, 20000 },
> +     { AD5758_RANGE_PLUSMINUS_24mA, -24000, 24000 },
> +     { AD5758_RANGE_MINUS_1mA_PLUS_22mA, -1000, 22000 },
> +};
> +
> +static const int ad5758_sr_clk[16] = {
> +     240000, 200000, 150000, 128000, 64000, 32000, 16000, 8000, 4000, 2000,
> +     1000, 512, 256, 128, 64, 16
> +};
> +
> +static const int ad5758_sr_step[8] = {
> +     4, 12, 64, 120, 256, 500, 1820, 2048
> +};
> +
> +static const int ad5758_dc_dc_ilim[6] = {
> +     150000, 200000, 250000, 300000, 350000, 400000
> +};
> +
> +static int ad5758_spi_reg_read(struct ad5758_state *st, unsigned int addr)
> +{
> +     struct spi_transfer t[] = {
> +             {
> +                     .tx_buf = &st->d32[0],
> +                     .len = 4,
> +                     .cs_change = 1,
> +             }, {
> +                     .tx_buf = &st->d32[1],
> +                     .rx_buf = &st->d32[2],
> +                     .len = 4,
> +             },
> +     };
> +     int ret;
> +
> +     st->d32[0] = cpu_to_be32(
> +             (AD5758_WR_FLAG_MSK(AD5758_TWO_STAGE_READBACK_SELECT) << 24) |
> +             (addr << 8));
> +     st->d32[1] = cpu_to_be32(AD5758_WR_FLAG_MSK(AD5758_NOP) << 24);
> +
> +     ret = spi_sync_transfer(st->spi, t, ARRAY_SIZE(t));
> +     if (ret < 0)
> +             return ret;
> +
> +     return (be32_to_cpu(st->d32[2]) >> 8) & 0xFFFF;
> +}
> +
> +static int ad5758_spi_reg_write(struct ad5758_state *st,
> +                             unsigned int addr,
> +                             unsigned int val)
> +{
> +     st->d32[0] = cpu_to_be32((AD5758_WR_FLAG_MSK(addr) << 24) |
> +                              ((val & 0xFFFF) << 8));
> +
> +     return spi_write(st->spi, &st->d32[0], sizeof(st->d32[0]));
> +}
> +
> +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 cmpfunc(const void *a, const void *b)
> +{
> +     return *(int *)a - *(int *)b;
> +}
> +
> +static int ad5758_find_closest_match(const int *array,
> +                                  unsigned int size, int val)
> +{
> +     int i;
> +
> +     for (i = 0; i < size; i++) {
> +             if (val <= array[i])
> +                     return i;
> +     }
> +
> +     return size - 1;
> +}
> +
> +static int ad5758_wait_for_task_complete(struct ad5758_state *st,
> +                                      unsigned int reg,
> +                                      unsigned int mask)
> +{
> +     unsigned int timeout;
> +     int ret;
> +
> +     timeout = 10;
> +     do {
> +             ret = ad5758_spi_reg_read(st, reg);
> +             if (ret < 0)
> +                     return ret;
> +
> +             if (!(ret & mask))
> +                     return 0;
> +
> +             usleep_range(100, 1000);
> +     } 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);
> +     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_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);
> +
> +     /* Perform a software reset and wait at least 100us */
> +     usleep_range(100, 1000);
> +
> +     return ret;
> +}
> +
> +static int ad5758_set_dc_dc_conv_mode(struct ad5758_state *st,
> +                                   enum ad5758_dc_dc_mode mode)
> +{
> +     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;
> +
> +     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_set(struct ad5758_state *st,
> +                             unsigned int sr_clk_idx,
> +                             unsigned int sr_step_idx)
> +{
> +     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;
> +     mode = AD5758_DAC_CONFIG_SR_EN_MODE(1) |
> +            AD5758_DAC_CONFIG_SR_STEP_MODE(sr_step_idx) |
> +            AD5758_DAC_CONFIG_SR_CLOCK_MODE(sr_clk_idx);
> +
> +     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_CAL_MEM_UNREFRESHED_MSK);
> +}
> +
> +static int ad5758_slew_rate_config(struct ad5758_state *st)
> +{
> +     unsigned int sr_clk_idx, sr_step_idx;
> +     int i, res;
> +     s64 diff_new, diff_old;
> +     u64 sr_step, calc_slew_time;
> +
> +     sr_clk_idx = 0;
> +     sr_step_idx = 0;
> +     diff_old = S64_MAX;
> +     /*
> +      * The slew time can be determined by using the formula:
> +      * Slew Time = (Full Scale Out / (Step Size x Update Clk Freq))
> +      * where Slew time is expressed in microseconds
> +      * Given the desired slew time, the following algorithm determines the
> +      * best match for the step size and the update clock frequency.
> +      */
> +     for (i = 0; i < ARRAY_SIZE(ad5758_sr_clk); i++) {
> +             /*
> +              * Go through each valid update clock freq and determine a raw
> +              * value for the step size by using the formula:
> +              * Step Size = Full Scale Out / (Update Clk Freq * Slew Time)
> +              */
> +             sr_step = AD5758_FULL_SCALE_MICRO;
> +             do_div(sr_step, ad5758_sr_clk[i]);
> +             do_div(sr_step, st->slew_time);
> +             /*
> +              * After a raw value for step size was determined, find the
> +              * closest valid match
> +              */
> +             res = ad5758_find_closest_match(ad5758_sr_step,
> +                                             ARRAY_SIZE(ad5758_sr_step),
> +                                             sr_step);
> +             /* Calculate the slew time */
> +             calc_slew_time = AD5758_FULL_SCALE_MICRO;
> +             do_div(calc_slew_time, ad5758_sr_step[res]);
> +             do_div(calc_slew_time, ad5758_sr_clk[i]);
> +             /*
> +              * Determine with how many microseconds the calculated slew time
> +              * is different from the desired slew time and store the diff
> +              * for the next iteration
> +              */
> +             diff_new = abs(st->slew_time - calc_slew_time);
> +             if (diff_new < diff_old) {
> +                     diff_old = diff_new;
> +                     sr_clk_idx = i;
> +                     sr_step_idx = res;
> +             }
> +     }
> +
> +     return ad5758_slew_rate_set(st, sr_clk_idx, sr_step_idx);
> +}
> +
> +static int ad5758_set_out_range(struct ad5758_state *st, int range)
> +{
> +     int ret;
> +
> +     ret = ad5758_spi_write_mask(st, AD5758_DAC_CONFIG,
> +                                 AD5758_DAC_CONFIG_RANGE_MSK,
> +                                 AD5758_DAC_CONFIG_RANGE_MODE(range));
> +     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_CAL_MEM_UNREFRESHED_MSK);
> +}
> +
> +static int ad5758_fault_prot_switch_en(struct ad5758_state *st, bool enable)
> +{
> +     int ret;
> +
> +     ret = ad5758_spi_write_mask(st, AD5758_DCDC_CONFIG1,
> +                     AD5758_DCDC_CONFIG1_PROT_SW_EN_MSK,
> +                     AD5758_DCDC_CONFIG1_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, bool enable)
> +{
> +     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_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) {
> +             ret = ad5758_spi_reg_read(st, reg);
> +             if (ret < 0) {
> +                     mutex_unlock(&st->lock);
> +                     return ret;
> +             }
> +
> +             *readval = ret;
> +             ret = 0;
> +     } else {
> +             ret = ad5758_spi_reg_write(st, reg, writeval);
> +     }
> +     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);
> +             mutex_unlock(&st->lock);
> +             if (ret < 0)
> +                     return ret;
> +
> +             *val = ret;
> +             return IIO_VAL_INT;
> +     case IIO_CHAN_INFO_SCALE:
> +             min = st->out_range.min;
> +             max = st->out_range.max;
> +             *val = (max - min) / 1000;
> +             *val2 = 16;
> +             return IIO_VAL_FRACTIONAL_LOG2;
> +     case IIO_CHAN_INFO_OFFSET:
> +             min = st->out_range.min;
> +             max = st->out_range.max;
> +             *val = ((min * (1 << 16)) / (max - min)) / 1000;
> +             return IIO_VAL_INT;
> +     default:
> +             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 ret;
> +     default:
> +             return -EINVAL;
> +     }
> +}
> +
> +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 = kstrtobool(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_PROT_SW_EN_MODE(val);
> +     dcdc_config1_msk = AD5758_DCDC_CONFIG1_DCDC_MODE_MSK |
> +                        AD5758_DCDC_CONFIG1_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_SHARED_BY_TYPE,
> +     },
> +     { }
> +};
> +
> +#define AD5758_DAC_CHAN(_chan_type) {                                \
> +     .type = (_chan_type),                                   \
> +     .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_RAW) |    \
> +             BIT(IIO_CHAN_INFO_SCALE) |                      \
> +             BIT(IIO_CHAN_INFO_OFFSET),                      \
> +     .indexed = 1,                                           \
> +     .output = 1,                                            \
> +     .ext_info = ad5758_ext_info,                            \
> +}
> +
> +static const struct iio_chan_spec ad5758_voltage_ch[] = {
> +     AD5758_DAC_CHAN(IIO_VOLTAGE)
> +};
> +
> +static const struct iio_chan_spec ad5758_current_ch[] = {
> +     AD5758_DAC_CHAN(IIO_CURRENT)
> +};
> +
> +static bool ad5758_is_valid_mode(enum ad5758_dc_dc_mode mode)
> +{
> +     switch (mode) {
> +     case AD5758_DCDC_MODE_DPC_CURRENT:
> +     case AD5758_DCDC_MODE_DPC_VOLTAGE:
> +     case AD5758_DCDC_MODE_PPC_CURRENT:
> +             return true;
> +     default:
> +             return false;
> +     }
> +}
> +
> +static int ad5758_crc_disable(struct ad5758_state *st)
> +{
> +     unsigned int mask;
> +
> +     mask = (AD5758_WR_FLAG_MSK(AD5758_DIGITAL_DIAG_CONFIG) << 24) | 0x5C3A;
> +     st->d32[0] = cpu_to_be32(mask);
> +
> +     return spi_write(st->spi, &st->d32[0], 4);
> +}
> +
> +static int ad5758_find_out_range(struct ad5758_state *st,
> +                              const struct ad5758_range *range,
> +                              unsigned int size,
> +                              int min, int max)
> +{
> +     int i;
> +
> +     for (i = 0; i < size; i++) {
> +             if ((min == range[i].min) && (max == range[i].max)) {
> +                     st->out_range.reg = range[i].reg;
> +                     st->out_range.min = range[i].min;
> +                     st->out_range.max = range[i].max;
> +
> +                     return 0;
> +             }
> +     }
> +
> +     return -EINVAL;
> +}
> +
> +static int ad5758_parse_dt(struct ad5758_state *st)
> +{
> +     unsigned int tmp, tmparray[2], size;
> +     const struct ad5758_range *range;
> +     int *index, ret;
> +
> +     st->dc_dc_ilim = 0;
> +     ret = device_property_read_u32(&st->spi->dev,
> +                                    "adi,dc-dc-ilim-microamp", &tmp);
> +     if (ret) {
> +             dev_dbg(&st->spi->dev,
> +                     "Missing \"dc-dc-ilim-microamp\" property\n");
> +     } else {
> +             index = bsearch(&tmp, ad5758_dc_dc_ilim,
> +                             ARRAY_SIZE(ad5758_dc_dc_ilim),
> +                             sizeof(int), cmpfunc);
> +             if (!index)
> +                     dev_dbg(&st->spi->dev, "dc-dc-ilim out of range\n");
> +             else
> +                     st->dc_dc_ilim = index - ad5758_dc_dc_ilim;
> +     }
> +
> +     ret = device_property_read_u32(&st->spi->dev, "adi,dc-dc-mode",
> +                                    &st->dc_dc_mode);
> +     if (ret) {
> +             dev_err(&st->spi->dev, "Missing \"dc-dc-mode\" property\n");
> +             return ret;
> +     }
> +
> +     if (!ad5758_is_valid_mode(st->dc_dc_mode))
> +             return -EINVAL;
> +
> +     if (st->dc_dc_mode == AD5758_DCDC_MODE_DPC_VOLTAGE) {
> +             ret = device_property_read_u32_array(&st->spi->dev,
> +                                                  "adi,range-microvolt",
> +                                                  tmparray, 2);
> +             if (ret) {
> +                     dev_err(&st->spi->dev,
> +                             "Missing \"range-microvolt\" property\n");
> +                     return ret;
> +             }
> +             range = ad5758_voltage_range;
> +             size = ARRAY_SIZE(ad5758_voltage_range);
> +     } else {
> +             ret = device_property_read_u32_array(&st->spi->dev,
> +                                                  "adi,range-microamp",
> +                                                  tmparray, 2);
> +             if (ret) {
> +                     dev_err(&st->spi->dev,
> +                             "Missing \"range-microamp\" property\n");
> +                     return ret;
> +             }
> +             range = ad5758_current_range;
> +             size = ARRAY_SIZE(ad5758_current_range);
> +     }
> +
> +     ret = ad5758_find_out_range(st, range, size, tmparray[0], tmparray[1]);
> +     if (ret) {
> +             dev_err(&st->spi->dev, "range invalid\n");
> +             return ret;
> +     }
> +
> +     ret = device_property_read_u32(&st->spi->dev, "adi,slew-time-us", &tmp);
> +     if (ret) {
> +             dev_dbg(&st->spi->dev, "Missing \"slew-time-us\" property\n");
> +             st->slew_time = 0;
> +     } else {
> +             st->slew_time = tmp;
> +     }
> +
> +     return 0;
> +}
> +
> +static int ad5758_init(struct ad5758_state *st)
> +{
> +     int regval, ret;
> +
> +     /* 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.reg);
> +     if (ret < 0)
> +             return ret;
> +
> +     /* Enable Slew Rate Control, set the slew rate clock and step */
> +     if (st->slew_time) {
> +             ret = ad5758_slew_rate_config(st);
> +             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 */
> +     return ad5758_spi_write_mask(st, AD5758_DAC_CONFIG,
> +                                  AD5758_DAC_CONFIG_OUT_EN_MSK,
> +                                  AD5758_DAC_CONFIG_OUT_EN_MODE(1));
> +}
> +
> +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;
> +
> +     mutex_init(&st->lock);
> +
> +     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->num_channels = 1;
> +
> +     ret = ad5758_parse_dt(st);
> +     if (ret < 0)
> +             return ret;
> +
> +     if (st->dc_dc_mode == AD5758_DCDC_MODE_DPC_VOLTAGE)
> +             indio_dev->channels = ad5758_voltage_ch;
> +     else
> +             indio_dev->channels = ad5758_current_ch;
> +
> +     ret = ad5758_init(st);
> +     if (ret < 0) {
> +             dev_err(&spi->dev, "AD5758 init failed\n");
> +             return ret;
> +     }
> +
> +     return devm_iio_device_register(&st->spi->dev, indio_dev);
> +}
> +
> +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");

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