Linux 4.19.133

[linux/fpc-iii.git] / drivers / iio / adc / meson_saradc.c

/*
 * Amlogic Meson Successive Approximation Register (SAR) A/D Converter
 *
 * Copyright (C) 2017 Martin Blumenstingl <martin.blumenstingl@googlemail.com>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program. If not, see <http://www.gnu.org/licenses/>.
 */

#include <linux/bitfield.h>
#include <linux/clk.h>
#include <linux/clk-provider.h>
#include <linux/delay.h>
#include <linux/io.h>
#include <linux/iio/iio.h>
#include <linux/module.h>
#include <linux/interrupt.h>
#include <linux/of.h>
#include <linux/of_irq.h>
#include <linux/of_device.h>
#include <linux/platform_device.h>
#include <linux/regmap.h>
#include <linux/regulator/consumer.h>

#define MESON_SAR_ADC_REG0                                      0x00
        #define MESON_SAR_ADC_REG0_PANEL_DETECT                 BIT(31)
        #define MESON_SAR_ADC_REG0_BUSY_MASK                    GENMASK(30, 28)
        #define MESON_SAR_ADC_REG0_DELTA_BUSY                   BIT(30)
        #define MESON_SAR_ADC_REG0_AVG_BUSY                     BIT(29)
        #define MESON_SAR_ADC_REG0_SAMPLE_BUSY                  BIT(28)
        #define MESON_SAR_ADC_REG0_FIFO_FULL                    BIT(27)
        #define MESON_SAR_ADC_REG0_FIFO_EMPTY                   BIT(26)
        #define MESON_SAR_ADC_REG0_FIFO_COUNT_MASK              GENMASK(25, 21)
        #define MESON_SAR_ADC_REG0_ADC_BIAS_CTRL_MASK           GENMASK(20, 19)
        #define MESON_SAR_ADC_REG0_CURR_CHAN_ID_MASK            GENMASK(18, 16)
        #define MESON_SAR_ADC_REG0_ADC_TEMP_SEN_SEL             BIT(15)
        #define MESON_SAR_ADC_REG0_SAMPLING_STOP                BIT(14)
        #define MESON_SAR_ADC_REG0_CHAN_DELTA_EN_MASK           GENMASK(13, 12)
        #define MESON_SAR_ADC_REG0_DETECT_IRQ_POL               BIT(10)
        #define MESON_SAR_ADC_REG0_DETECT_IRQ_EN                BIT(9)
        #define MESON_SAR_ADC_REG0_FIFO_CNT_IRQ_MASK            GENMASK(8, 4)
        #define MESON_SAR_ADC_REG0_FIFO_IRQ_EN                  BIT(3)
        #define MESON_SAR_ADC_REG0_SAMPLING_START               BIT(2)
        #define MESON_SAR_ADC_REG0_CONTINUOUS_EN                BIT(1)
        #define MESON_SAR_ADC_REG0_SAMPLE_ENGINE_ENABLE         BIT(0)

#define MESON_SAR_ADC_CHAN_LIST                                 0x04
        #define MESON_SAR_ADC_CHAN_LIST_MAX_INDEX_MASK          GENMASK(26, 24)
        #define MESON_SAR_ADC_CHAN_LIST_ENTRY_MASK(_chan)       \
                                        (GENMASK(2, 0) << ((_chan) * 3))

#define MESON_SAR_ADC_AVG_CNTL                                  0x08
        #define MESON_SAR_ADC_AVG_CNTL_AVG_MODE_SHIFT(_chan)    \
                                        (16 + ((_chan) * 2))
        #define MESON_SAR_ADC_AVG_CNTL_AVG_MODE_MASK(_chan)     \
                                        (GENMASK(17, 16) << ((_chan) * 2))
        #define MESON_SAR_ADC_AVG_CNTL_NUM_SAMPLES_SHIFT(_chan) \
                                        (0 + ((_chan) * 2))
        #define MESON_SAR_ADC_AVG_CNTL_NUM_SAMPLES_MASK(_chan)  \
                                        (GENMASK(1, 0) << ((_chan) * 2))

#define MESON_SAR_ADC_REG3                                      0x0c
        #define MESON_SAR_ADC_REG3_CNTL_USE_SC_DLY              BIT(31)
        #define MESON_SAR_ADC_REG3_CLK_EN                       BIT(30)
        #define MESON_SAR_ADC_REG3_BL30_INITIALIZED             BIT(28)
        #define MESON_SAR_ADC_REG3_CTRL_CONT_RING_COUNTER_EN    BIT(27)
        #define MESON_SAR_ADC_REG3_CTRL_SAMPLING_CLOCK_PHASE    BIT(26)
        #define MESON_SAR_ADC_REG3_CTRL_CHAN7_MUX_SEL_MASK      GENMASK(25, 23)
        #define MESON_SAR_ADC_REG3_DETECT_EN                    BIT(22)
        #define MESON_SAR_ADC_REG3_ADC_EN                       BIT(21)
        #define MESON_SAR_ADC_REG3_PANEL_DETECT_COUNT_MASK      GENMASK(20, 18)
        #define MESON_SAR_ADC_REG3_PANEL_DETECT_FILTER_TB_MASK  GENMASK(17, 16)
        #define MESON_SAR_ADC_REG3_ADC_CLK_DIV_SHIFT            10
        #define MESON_SAR_ADC_REG3_ADC_CLK_DIV_WIDTH            5
        #define MESON_SAR_ADC_REG3_BLOCK_DLY_SEL_MASK           GENMASK(9, 8)
        #define MESON_SAR_ADC_REG3_BLOCK_DLY_MASK               GENMASK(7, 0)

#define MESON_SAR_ADC_DELAY                                     0x10
        #define MESON_SAR_ADC_DELAY_INPUT_DLY_SEL_MASK          GENMASK(25, 24)
        #define MESON_SAR_ADC_DELAY_BL30_BUSY                   BIT(15)
        #define MESON_SAR_ADC_DELAY_KERNEL_BUSY                 BIT(14)
        #define MESON_SAR_ADC_DELAY_INPUT_DLY_CNT_MASK          GENMASK(23, 16)
        #define MESON_SAR_ADC_DELAY_SAMPLE_DLY_SEL_MASK         GENMASK(9, 8)
        #define MESON_SAR_ADC_DELAY_SAMPLE_DLY_CNT_MASK         GENMASK(7, 0)

#define MESON_SAR_ADC_LAST_RD                                   0x14
        #define MESON_SAR_ADC_LAST_RD_LAST_CHANNEL1_MASK        GENMASK(23, 16)
        #define MESON_SAR_ADC_LAST_RD_LAST_CHANNEL0_MASK        GENMASK(9, 0)

#define MESON_SAR_ADC_FIFO_RD                                   0x18
        #define MESON_SAR_ADC_FIFO_RD_CHAN_ID_MASK              GENMASK(14, 12)
        #define MESON_SAR_ADC_FIFO_RD_SAMPLE_VALUE_MASK         GENMASK(11, 0)

#define MESON_SAR_ADC_AUX_SW                                    0x1c
        #define MESON_SAR_ADC_AUX_SW_MUX_SEL_CHAN_SHIFT(_chan)  \
                                        (8 + (((_chan) - 2) * 3))
        #define MESON_SAR_ADC_AUX_SW_VREF_P_MUX                 BIT(6)
        #define MESON_SAR_ADC_AUX_SW_VREF_N_MUX                 BIT(5)
        #define MESON_SAR_ADC_AUX_SW_MODE_SEL                   BIT(4)
        #define MESON_SAR_ADC_AUX_SW_YP_DRIVE_SW                BIT(3)
        #define MESON_SAR_ADC_AUX_SW_XP_DRIVE_SW                BIT(2)
        #define MESON_SAR_ADC_AUX_SW_YM_DRIVE_SW                BIT(1)
        #define MESON_SAR_ADC_AUX_SW_XM_DRIVE_SW                BIT(0)

#define MESON_SAR_ADC_CHAN_10_SW                                0x20
        #define MESON_SAR_ADC_CHAN_10_SW_CHAN1_MUX_SEL_MASK     GENMASK(25, 23)
        #define MESON_SAR_ADC_CHAN_10_SW_CHAN1_VREF_P_MUX       BIT(22)
        #define MESON_SAR_ADC_CHAN_10_SW_CHAN1_VREF_N_MUX       BIT(21)
        #define MESON_SAR_ADC_CHAN_10_SW_CHAN1_MODE_SEL         BIT(20)
        #define MESON_SAR_ADC_CHAN_10_SW_CHAN1_YP_DRIVE_SW      BIT(19)
        #define MESON_SAR_ADC_CHAN_10_SW_CHAN1_XP_DRIVE_SW      BIT(18)
        #define MESON_SAR_ADC_CHAN_10_SW_CHAN1_YM_DRIVE_SW      BIT(17)
        #define MESON_SAR_ADC_CHAN_10_SW_CHAN1_XM_DRIVE_SW      BIT(16)
        #define MESON_SAR_ADC_CHAN_10_SW_CHAN0_MUX_SEL_MASK     GENMASK(9, 7)
        #define MESON_SAR_ADC_CHAN_10_SW_CHAN0_VREF_P_MUX       BIT(6)
        #define MESON_SAR_ADC_CHAN_10_SW_CHAN0_VREF_N_MUX       BIT(5)
        #define MESON_SAR_ADC_CHAN_10_SW_CHAN0_MODE_SEL         BIT(4)
        #define MESON_SAR_ADC_CHAN_10_SW_CHAN0_YP_DRIVE_SW      BIT(3)
        #define MESON_SAR_ADC_CHAN_10_SW_CHAN0_XP_DRIVE_SW      BIT(2)
        #define MESON_SAR_ADC_CHAN_10_SW_CHAN0_YM_DRIVE_SW      BIT(1)
        #define MESON_SAR_ADC_CHAN_10_SW_CHAN0_XM_DRIVE_SW      BIT(0)

#define MESON_SAR_ADC_DETECT_IDLE_SW                            0x24
        #define MESON_SAR_ADC_DETECT_IDLE_SW_DETECT_SW_EN       BIT(26)
        #define MESON_SAR_ADC_DETECT_IDLE_SW_DETECT_MUX_MASK    GENMASK(25, 23)
        #define MESON_SAR_ADC_DETECT_IDLE_SW_DETECT_VREF_P_MUX  BIT(22)
        #define MESON_SAR_ADC_DETECT_IDLE_SW_DETECT_VREF_N_MUX  BIT(21)
        #define MESON_SAR_ADC_DETECT_IDLE_SW_DETECT_MODE_SEL    BIT(20)
        #define MESON_SAR_ADC_DETECT_IDLE_SW_DETECT_YP_DRIVE_SW BIT(19)
        #define MESON_SAR_ADC_DETECT_IDLE_SW_DETECT_XP_DRIVE_SW BIT(18)
        #define MESON_SAR_ADC_DETECT_IDLE_SW_DETECT_YM_DRIVE_SW BIT(17)
        #define MESON_SAR_ADC_DETECT_IDLE_SW_DETECT_XM_DRIVE_SW BIT(16)
        #define MESON_SAR_ADC_DETECT_IDLE_SW_IDLE_MUX_SEL_MASK  GENMASK(9, 7)
        #define MESON_SAR_ADC_DETECT_IDLE_SW_IDLE_VREF_P_MUX    BIT(6)
        #define MESON_SAR_ADC_DETECT_IDLE_SW_IDLE_VREF_N_MUX    BIT(5)
        #define MESON_SAR_ADC_DETECT_IDLE_SW_IDLE_MODE_SEL      BIT(4)
        #define MESON_SAR_ADC_DETECT_IDLE_SW_IDLE_YP_DRIVE_SW   BIT(3)
        #define MESON_SAR_ADC_DETECT_IDLE_SW_IDLE_XP_DRIVE_SW   BIT(2)
        #define MESON_SAR_ADC_DETECT_IDLE_SW_IDLE_YM_DRIVE_SW   BIT(1)
        #define MESON_SAR_ADC_DETECT_IDLE_SW_IDLE_XM_DRIVE_SW   BIT(0)

#define MESON_SAR_ADC_DELTA_10                                  0x28
        #define MESON_SAR_ADC_DELTA_10_TEMP_SEL                 BIT(27)
        #define MESON_SAR_ADC_DELTA_10_TS_REVE1                 BIT(26)
        #define MESON_SAR_ADC_DELTA_10_CHAN1_DELTA_VALUE_MASK   GENMASK(25, 16)
        #define MESON_SAR_ADC_DELTA_10_TS_REVE0                 BIT(15)
        #define MESON_SAR_ADC_DELTA_10_TS_C_SHIFT               11
        #define MESON_SAR_ADC_DELTA_10_TS_C_MASK                GENMASK(14, 11)
        #define MESON_SAR_ADC_DELTA_10_TS_VBG_EN                BIT(10)
        #define MESON_SAR_ADC_DELTA_10_CHAN0_DELTA_VALUE_MASK   GENMASK(9, 0)

/*
 * NOTE: registers from here are undocumented (the vendor Linux kernel driver
 * and u-boot source served as reference). These only seem to be relevant on
 * GXBB and newer.
 */
#define MESON_SAR_ADC_REG11                                     0x2c
        #define MESON_SAR_ADC_REG11_BANDGAP_EN                  BIT(13)

#define MESON_SAR_ADC_REG13                                     0x34
        #define MESON_SAR_ADC_REG13_12BIT_CALIBRATION_MASK      GENMASK(13, 8)

#define MESON_SAR_ADC_MAX_FIFO_SIZE                             32
#define MESON_SAR_ADC_TIMEOUT                                   100 /* ms */
/* for use with IIO_VAL_INT_PLUS_MICRO */
#define MILLION                                                 1000000

#define MESON_SAR_ADC_CHAN(_chan) {                                     \
        .type = IIO_VOLTAGE,                                            \
        .indexed = 1,                                                   \
        .channel = _chan,                                               \
        .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |                  \
                                BIT(IIO_CHAN_INFO_AVERAGE_RAW),         \
        .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE) |          \
                                BIT(IIO_CHAN_INFO_CALIBBIAS) |          \
                                BIT(IIO_CHAN_INFO_CALIBSCALE),          \
        .datasheet_name = "SAR_ADC_CH"#_chan,                           \
}

/*
 * TODO: the hardware supports IIO_TEMP for channel 6 as well which is
 * currently not supported by this driver.
 */
static const struct iio_chan_spec meson_sar_adc_iio_channels[] = {
        MESON_SAR_ADC_CHAN(0),
        MESON_SAR_ADC_CHAN(1),
        MESON_SAR_ADC_CHAN(2),
        MESON_SAR_ADC_CHAN(3),
        MESON_SAR_ADC_CHAN(4),
        MESON_SAR_ADC_CHAN(5),
        MESON_SAR_ADC_CHAN(6),
        MESON_SAR_ADC_CHAN(7),
        IIO_CHAN_SOFT_TIMESTAMP(8),
};

enum meson_sar_adc_avg_mode {
        NO_AVERAGING = 0x0,
        MEAN_AVERAGING = 0x1,
        MEDIAN_AVERAGING = 0x2,
};

enum meson_sar_adc_num_samples {
        ONE_SAMPLE = 0x0,
        TWO_SAMPLES = 0x1,
        FOUR_SAMPLES = 0x2,
        EIGHT_SAMPLES = 0x3,
};

enum meson_sar_adc_chan7_mux_sel {
        CHAN7_MUX_VSS = 0x0,
        CHAN7_MUX_VDD_DIV4 = 0x1,
        CHAN7_MUX_VDD_DIV2 = 0x2,
        CHAN7_MUX_VDD_MUL3_DIV4 = 0x3,
        CHAN7_MUX_VDD = 0x4,
        CHAN7_MUX_CH7_INPUT = 0x7,
};

struct meson_sar_adc_param {
        bool                                    has_bl30_integration;
        unsigned long                           clock_rate;
        u32                                     bandgap_reg;
        unsigned int                            resolution;
        const struct regmap_config              *regmap_config;
};

struct meson_sar_adc_data {
        const struct meson_sar_adc_param        *param;
        const char                              *name;
};

struct meson_sar_adc_priv {
        struct regmap                           *regmap;
        struct regulator                        *vref;
        const struct meson_sar_adc_data         *data;
        struct clk                              *clkin;
        struct clk                              *core_clk;
        struct clk                              *adc_sel_clk;
        struct clk                              *adc_clk;
        struct clk_gate                         clk_gate;
        struct clk                              *adc_div_clk;
        struct clk_divider                      clk_div;
        struct completion                       done;
        int                                     calibbias;
        int                                     calibscale;
};

static const struct regmap_config meson_sar_adc_regmap_config_gxbb = {
        .reg_bits = 8,
        .val_bits = 32,
        .reg_stride = 4,
        .max_register = MESON_SAR_ADC_REG13,
};

static const struct regmap_config meson_sar_adc_regmap_config_meson8 = {
        .reg_bits = 8,
        .val_bits = 32,
        .reg_stride = 4,
        .max_register = MESON_SAR_ADC_DELTA_10,
};

static unsigned int meson_sar_adc_get_fifo_count(struct iio_dev *indio_dev)
{
        struct meson_sar_adc_priv *priv = iio_priv(indio_dev);
        u32 regval;

        regmap_read(priv->regmap, MESON_SAR_ADC_REG0, &regval);

        return FIELD_GET(MESON_SAR_ADC_REG0_FIFO_COUNT_MASK, regval);
}

static int meson_sar_adc_calib_val(struct iio_dev *indio_dev, int val)
{
        struct meson_sar_adc_priv *priv = iio_priv(indio_dev);
        int tmp;

        /* use val_calib = scale * val_raw + offset calibration function */
        tmp = div_s64((s64)val * priv->calibscale, MILLION) + priv->calibbias;

        return clamp(tmp, 0, (1 << priv->data->param->resolution) - 1);
}

static int meson_sar_adc_wait_busy_clear(struct iio_dev *indio_dev)
{
        struct meson_sar_adc_priv *priv = iio_priv(indio_dev);
        int regval, timeout = 10000;

        /*
         * NOTE: we need a small delay before reading the status, otherwise
         * the sample engine may not have started internally (which would
         * seem to us that sampling is already finished).
         */
        do {
                udelay(1);
                regmap_read(priv->regmap, MESON_SAR_ADC_REG0, &regval);
        } while (FIELD_GET(MESON_SAR_ADC_REG0_BUSY_MASK, regval) && timeout--);

        if (timeout < 0)
                return -ETIMEDOUT;

        return 0;
}

static int meson_sar_adc_read_raw_sample(struct iio_dev *indio_dev,
                                         const struct iio_chan_spec *chan,
                                         int *val)
{
        struct meson_sar_adc_priv *priv = iio_priv(indio_dev);
        int regval, fifo_chan, fifo_val, count;

        if(!wait_for_completion_timeout(&priv->done,
                                msecs_to_jiffies(MESON_SAR_ADC_TIMEOUT)))
                return -ETIMEDOUT;

        count = meson_sar_adc_get_fifo_count(indio_dev);
        if (count != 1) {
                dev_err(&indio_dev->dev,
                        "ADC FIFO has %d element(s) instead of one\n", count);
                return -EINVAL;
        }

        regmap_read(priv->regmap, MESON_SAR_ADC_FIFO_RD, &regval);
        fifo_chan = FIELD_GET(MESON_SAR_ADC_FIFO_RD_CHAN_ID_MASK, regval);
        if (fifo_chan != chan->channel) {
                dev_err(&indio_dev->dev,
                        "ADC FIFO entry belongs to channel %d instead of %d\n",
                        fifo_chan, chan->channel);
                return -EINVAL;
        }

        fifo_val = FIELD_GET(MESON_SAR_ADC_FIFO_RD_SAMPLE_VALUE_MASK, regval);
        fifo_val &= GENMASK(priv->data->param->resolution - 1, 0);
        *val = meson_sar_adc_calib_val(indio_dev, fifo_val);

        return 0;
}

static void meson_sar_adc_set_averaging(struct iio_dev *indio_dev,
                                        const struct iio_chan_spec *chan,
                                        enum meson_sar_adc_avg_mode mode,
                                        enum meson_sar_adc_num_samples samples)
{
        struct meson_sar_adc_priv *priv = iio_priv(indio_dev);
        int val, channel = chan->channel;

        val = samples << MESON_SAR_ADC_AVG_CNTL_NUM_SAMPLES_SHIFT(channel);
        regmap_update_bits(priv->regmap, MESON_SAR_ADC_AVG_CNTL,
                           MESON_SAR_ADC_AVG_CNTL_NUM_SAMPLES_MASK(channel),
                           val);

        val = mode << MESON_SAR_ADC_AVG_CNTL_AVG_MODE_SHIFT(channel);
        regmap_update_bits(priv->regmap, MESON_SAR_ADC_AVG_CNTL,
                           MESON_SAR_ADC_AVG_CNTL_AVG_MODE_MASK(channel), val);
}

static void meson_sar_adc_enable_channel(struct iio_dev *indio_dev,
                                        const struct iio_chan_spec *chan)
{
        struct meson_sar_adc_priv *priv = iio_priv(indio_dev);
        u32 regval;

        /*
         * the SAR ADC engine allows sampling multiple channels at the same
         * time. to keep it simple we're only working with one *internal*
         * channel, which starts counting at index 0 (which means: count = 1).
         */
        regval = FIELD_PREP(MESON_SAR_ADC_CHAN_LIST_MAX_INDEX_MASK, 0);
        regmap_update_bits(priv->regmap, MESON_SAR_ADC_CHAN_LIST,
                           MESON_SAR_ADC_CHAN_LIST_MAX_INDEX_MASK, regval);

        /* map channel index 0 to the channel which we want to read */
        regval = FIELD_PREP(MESON_SAR_ADC_CHAN_LIST_ENTRY_MASK(0),
                            chan->channel);
        regmap_update_bits(priv->regmap, MESON_SAR_ADC_CHAN_LIST,
                           MESON_SAR_ADC_CHAN_LIST_ENTRY_MASK(0), regval);

        regval = FIELD_PREP(MESON_SAR_ADC_DETECT_IDLE_SW_DETECT_MUX_MASK,
                            chan->channel);
        regmap_update_bits(priv->regmap, MESON_SAR_ADC_DETECT_IDLE_SW,
                           MESON_SAR_ADC_DETECT_IDLE_SW_DETECT_MUX_MASK,
                           regval);

        regval = FIELD_PREP(MESON_SAR_ADC_DETECT_IDLE_SW_IDLE_MUX_SEL_MASK,
                            chan->channel);
        regmap_update_bits(priv->regmap, MESON_SAR_ADC_DETECT_IDLE_SW,
                           MESON_SAR_ADC_DETECT_IDLE_SW_IDLE_MUX_SEL_MASK,
                           regval);

        if (chan->channel == 6)
                regmap_update_bits(priv->regmap, MESON_SAR_ADC_DELTA_10,
                                   MESON_SAR_ADC_DELTA_10_TEMP_SEL, 0);
}

static void meson_sar_adc_set_chan7_mux(struct iio_dev *indio_dev,
                                        enum meson_sar_adc_chan7_mux_sel sel)
{
        struct meson_sar_adc_priv *priv = iio_priv(indio_dev);
        u32 regval;

        regval = FIELD_PREP(MESON_SAR_ADC_REG3_CTRL_CHAN7_MUX_SEL_MASK, sel);
        regmap_update_bits(priv->regmap, MESON_SAR_ADC_REG3,
                           MESON_SAR_ADC_REG3_CTRL_CHAN7_MUX_SEL_MASK, regval);

        usleep_range(10, 20);
}

static void meson_sar_adc_start_sample_engine(struct iio_dev *indio_dev)
{
        struct meson_sar_adc_priv *priv = iio_priv(indio_dev);

        reinit_completion(&priv->done);

        regmap_update_bits(priv->regmap, MESON_SAR_ADC_REG0,
                           MESON_SAR_ADC_REG0_FIFO_IRQ_EN,
                           MESON_SAR_ADC_REG0_FIFO_IRQ_EN);

        regmap_update_bits(priv->regmap, MESON_SAR_ADC_REG0,
                           MESON_SAR_ADC_REG0_SAMPLE_ENGINE_ENABLE,
                           MESON_SAR_ADC_REG0_SAMPLE_ENGINE_ENABLE);

        regmap_update_bits(priv->regmap, MESON_SAR_ADC_REG0,
                           MESON_SAR_ADC_REG0_SAMPLING_START,
                           MESON_SAR_ADC_REG0_SAMPLING_START);
}

static void meson_sar_adc_stop_sample_engine(struct iio_dev *indio_dev)
{
        struct meson_sar_adc_priv *priv = iio_priv(indio_dev);

        regmap_update_bits(priv->regmap, MESON_SAR_ADC_REG0,
                           MESON_SAR_ADC_REG0_FIFO_IRQ_EN, 0);

        regmap_update_bits(priv->regmap, MESON_SAR_ADC_REG0,
                           MESON_SAR_ADC_REG0_SAMPLING_STOP,
                           MESON_SAR_ADC_REG0_SAMPLING_STOP);

        /* wait until all modules are stopped */
        meson_sar_adc_wait_busy_clear(indio_dev);

        regmap_update_bits(priv->regmap, MESON_SAR_ADC_REG0,
                           MESON_SAR_ADC_REG0_SAMPLE_ENGINE_ENABLE, 0);
}

static int meson_sar_adc_lock(struct iio_dev *indio_dev)
{
        struct meson_sar_adc_priv *priv = iio_priv(indio_dev);
        int val, timeout = 10000;

        mutex_lock(&indio_dev->mlock);

        if (priv->data->param->has_bl30_integration) {
                /* prevent BL30 from using the SAR ADC while we are using it */
                regmap_update_bits(priv->regmap, MESON_SAR_ADC_DELAY,
                                MESON_SAR_ADC_DELAY_KERNEL_BUSY,
                                MESON_SAR_ADC_DELAY_KERNEL_BUSY);

                /*
                 * wait until BL30 releases it's lock (so we can use the SAR
                 * ADC)
                 */
                do {
                        udelay(1);
                        regmap_read(priv->regmap, MESON_SAR_ADC_DELAY, &val);
                } while (val & MESON_SAR_ADC_DELAY_BL30_BUSY && timeout--);

                if (timeout < 0) {
                        mutex_unlock(&indio_dev->mlock);
                        return -ETIMEDOUT;
                }
        }

        return 0;
}

static void meson_sar_adc_unlock(struct iio_dev *indio_dev)
{
        struct meson_sar_adc_priv *priv = iio_priv(indio_dev);

        if (priv->data->param->has_bl30_integration)
                /* allow BL30 to use the SAR ADC again */
                regmap_update_bits(priv->regmap, MESON_SAR_ADC_DELAY,
                                MESON_SAR_ADC_DELAY_KERNEL_BUSY, 0);

        mutex_unlock(&indio_dev->mlock);
}

static void meson_sar_adc_clear_fifo(struct iio_dev *indio_dev)
{
        struct meson_sar_adc_priv *priv = iio_priv(indio_dev);
        unsigned int count, tmp;

        for (count = 0; count < MESON_SAR_ADC_MAX_FIFO_SIZE; count++) {
                if (!meson_sar_adc_get_fifo_count(indio_dev))
                        break;

                regmap_read(priv->regmap, MESON_SAR_ADC_FIFO_RD, &tmp);
        }
}

static int meson_sar_adc_get_sample(struct iio_dev *indio_dev,
                                    const struct iio_chan_spec *chan,
                                    enum meson_sar_adc_avg_mode avg_mode,
                                    enum meson_sar_adc_num_samples avg_samples,
                                    int *val)
{
        int ret;

        ret = meson_sar_adc_lock(indio_dev);
        if (ret)
                return ret;

        /* clear the FIFO to make sure we're not reading old values */
        meson_sar_adc_clear_fifo(indio_dev);

        meson_sar_adc_set_averaging(indio_dev, chan, avg_mode, avg_samples);

        meson_sar_adc_enable_channel(indio_dev, chan);

        meson_sar_adc_start_sample_engine(indio_dev);
        ret = meson_sar_adc_read_raw_sample(indio_dev, chan, val);
        meson_sar_adc_stop_sample_engine(indio_dev);

        meson_sar_adc_unlock(indio_dev);

        if (ret) {
                dev_warn(indio_dev->dev.parent,
                         "failed to read sample for channel %d: %d\n",
                         chan->channel, ret);
                return ret;
        }

        return IIO_VAL_INT;
}

static int meson_sar_adc_iio_info_read_raw(struct iio_dev *indio_dev,
                                           const struct iio_chan_spec *chan,
                                           int *val, int *val2, long mask)
{
        struct meson_sar_adc_priv *priv = iio_priv(indio_dev);
        int ret;

        switch (mask) {
        case IIO_CHAN_INFO_RAW:
                return meson_sar_adc_get_sample(indio_dev, chan, NO_AVERAGING,
                                                ONE_SAMPLE, val);
                break;

        case IIO_CHAN_INFO_AVERAGE_RAW:
                return meson_sar_adc_get_sample(indio_dev, chan,
                                                MEAN_AVERAGING, EIGHT_SAMPLES,
                                                val);
                break;

        case IIO_CHAN_INFO_SCALE:
                ret = regulator_get_voltage(priv->vref);
                if (ret < 0) {
                        dev_err(indio_dev->dev.parent,
                                "failed to get vref voltage: %d\n", ret);
                        return ret;
                }

                *val = ret / 1000;
                *val2 = priv->data->param->resolution;
                return IIO_VAL_FRACTIONAL_LOG2;

        case IIO_CHAN_INFO_CALIBBIAS:
                *val = priv->calibbias;
                return IIO_VAL_INT;

        case IIO_CHAN_INFO_CALIBSCALE:
                *val = priv->calibscale / MILLION;
                *val2 = priv->calibscale % MILLION;
                return IIO_VAL_INT_PLUS_MICRO;

        default:
                return -EINVAL;
        }
}

static int meson_sar_adc_clk_init(struct iio_dev *indio_dev,
                                  void __iomem *base)
{
        struct meson_sar_adc_priv *priv = iio_priv(indio_dev);
        struct clk_init_data init;
        const char *clk_parents[1];

        init.name = devm_kasprintf(&indio_dev->dev, GFP_KERNEL, "%s#adc_div",
                                   dev_name(indio_dev->dev.parent));
        if (!init.name)
                return -ENOMEM;

        init.flags = 0;
        init.ops = &clk_divider_ops;
        clk_parents[0] = __clk_get_name(priv->clkin);
        init.parent_names = clk_parents;
        init.num_parents = 1;

        priv->clk_div.reg = base + MESON_SAR_ADC_REG3;
        priv->clk_div.shift = MESON_SAR_ADC_REG3_ADC_CLK_DIV_SHIFT;
        priv->clk_div.width = MESON_SAR_ADC_REG3_ADC_CLK_DIV_WIDTH;
        priv->clk_div.hw.init = &init;
        priv->clk_div.flags = 0;

        priv->adc_div_clk = devm_clk_register(&indio_dev->dev,
                                              &priv->clk_div.hw);
        if (WARN_ON(IS_ERR(priv->adc_div_clk)))
                return PTR_ERR(priv->adc_div_clk);

        init.name = devm_kasprintf(&indio_dev->dev, GFP_KERNEL, "%s#adc_en",
                                   dev_name(indio_dev->dev.parent));
        if (!init.name)
                return -ENOMEM;

        init.flags = CLK_SET_RATE_PARENT;
        init.ops = &clk_gate_ops;
        clk_parents[0] = __clk_get_name(priv->adc_div_clk);
        init.parent_names = clk_parents;
        init.num_parents = 1;

        priv->clk_gate.reg = base + MESON_SAR_ADC_REG3;
        priv->clk_gate.bit_idx = __ffs(MESON_SAR_ADC_REG3_CLK_EN);
        priv->clk_gate.hw.init = &init;

        priv->adc_clk = devm_clk_register(&indio_dev->dev, &priv->clk_gate.hw);
        if (WARN_ON(IS_ERR(priv->adc_clk)))
                return PTR_ERR(priv->adc_clk);

        return 0;
}

static int meson_sar_adc_init(struct iio_dev *indio_dev)
{
        struct meson_sar_adc_priv *priv = iio_priv(indio_dev);
        int regval, i, ret;

        /*
         * make sure we start at CH7 input since the other muxes are only used
         * for internal calibration.
         */
        meson_sar_adc_set_chan7_mux(indio_dev, CHAN7_MUX_CH7_INPUT);

        if (priv->data->param->has_bl30_integration) {
                /*
                 * leave sampling delay and the input clocks as configured by
                 * BL30 to make sure BL30 gets the values it expects when
                 * reading the temperature sensor.
                 */
                regmap_read(priv->regmap, MESON_SAR_ADC_REG3, &regval);
                if (regval & MESON_SAR_ADC_REG3_BL30_INITIALIZED)
                        return 0;
        }

        meson_sar_adc_stop_sample_engine(indio_dev);

        /* update the channel 6 MUX to select the temperature sensor */
        regmap_update_bits(priv->regmap, MESON_SAR_ADC_REG0,
                        MESON_SAR_ADC_REG0_ADC_TEMP_SEN_SEL,
                        MESON_SAR_ADC_REG0_ADC_TEMP_SEN_SEL);

        /* disable all channels by default */
        regmap_write(priv->regmap, MESON_SAR_ADC_CHAN_LIST, 0x0);

        regmap_update_bits(priv->regmap, MESON_SAR_ADC_REG3,
                           MESON_SAR_ADC_REG3_CTRL_SAMPLING_CLOCK_PHASE, 0);
        regmap_update_bits(priv->regmap, MESON_SAR_ADC_REG3,
                           MESON_SAR_ADC_REG3_CNTL_USE_SC_DLY,
                           MESON_SAR_ADC_REG3_CNTL_USE_SC_DLY);

        /* delay between two samples = (10+1) * 1uS */
        regmap_update_bits(priv->regmap, MESON_SAR_ADC_DELAY,
                           MESON_SAR_ADC_DELAY_INPUT_DLY_CNT_MASK,
                           FIELD_PREP(MESON_SAR_ADC_DELAY_SAMPLE_DLY_CNT_MASK,
                                      10));
        regmap_update_bits(priv->regmap, MESON_SAR_ADC_DELAY,
                           MESON_SAR_ADC_DELAY_SAMPLE_DLY_SEL_MASK,
                           FIELD_PREP(MESON_SAR_ADC_DELAY_SAMPLE_DLY_SEL_MASK,
                                      0));

        /* delay between two samples = (10+1) * 1uS */
        regmap_update_bits(priv->regmap, MESON_SAR_ADC_DELAY,
                           MESON_SAR_ADC_DELAY_INPUT_DLY_CNT_MASK,
                           FIELD_PREP(MESON_SAR_ADC_DELAY_INPUT_DLY_CNT_MASK,
                                      10));
        regmap_update_bits(priv->regmap, MESON_SAR_ADC_DELAY,
                           MESON_SAR_ADC_DELAY_INPUT_DLY_SEL_MASK,
                           FIELD_PREP(MESON_SAR_ADC_DELAY_INPUT_DLY_SEL_MASK,
                                      1));

        /*
         * set up the input channel muxes in MESON_SAR_ADC_CHAN_10_SW
         * (0 = SAR_ADC_CH0, 1 = SAR_ADC_CH1)
         */
        regval = FIELD_PREP(MESON_SAR_ADC_CHAN_10_SW_CHAN0_MUX_SEL_MASK, 0);
        regmap_update_bits(priv->regmap, MESON_SAR_ADC_CHAN_10_SW,
                           MESON_SAR_ADC_CHAN_10_SW_CHAN0_MUX_SEL_MASK,
                           regval);
        regval = FIELD_PREP(MESON_SAR_ADC_CHAN_10_SW_CHAN1_MUX_SEL_MASK, 1);
        regmap_update_bits(priv->regmap, MESON_SAR_ADC_CHAN_10_SW,
                           MESON_SAR_ADC_CHAN_10_SW_CHAN1_MUX_SEL_MASK,
                           regval);

        /*
         * set up the input channel muxes in MESON_SAR_ADC_AUX_SW
         * (2 = SAR_ADC_CH2, 3 = SAR_ADC_CH3, ...) and enable
         * MESON_SAR_ADC_AUX_SW_YP_DRIVE_SW and
         * MESON_SAR_ADC_AUX_SW_XP_DRIVE_SW like the vendor driver.
         */
        regval = 0;
        for (i = 2; i <= 7; i++)
                regval |= i << MESON_SAR_ADC_AUX_SW_MUX_SEL_CHAN_SHIFT(i);
        regval |= MESON_SAR_ADC_AUX_SW_YP_DRIVE_SW;
        regval |= MESON_SAR_ADC_AUX_SW_XP_DRIVE_SW;
        regmap_write(priv->regmap, MESON_SAR_ADC_AUX_SW, regval);

        ret = clk_set_parent(priv->adc_sel_clk, priv->clkin);
        if (ret) {
                dev_err(indio_dev->dev.parent,
                        "failed to set adc parent to clkin\n");
                return ret;
        }

        ret = clk_set_rate(priv->adc_clk, priv->data->param->clock_rate);
        if (ret) {
                dev_err(indio_dev->dev.parent,
                        "failed to set adc clock rate\n");
                return ret;
        }

        return 0;
}

static void meson_sar_adc_set_bandgap(struct iio_dev *indio_dev, bool on_off)
{
        struct meson_sar_adc_priv *priv = iio_priv(indio_dev);
        const struct meson_sar_adc_param *param = priv->data->param;
        u32 enable_mask;

        if (param->bandgap_reg == MESON_SAR_ADC_REG11)
                enable_mask = MESON_SAR_ADC_REG11_BANDGAP_EN;
        else
                enable_mask = MESON_SAR_ADC_DELTA_10_TS_VBG_EN;

        regmap_update_bits(priv->regmap, param->bandgap_reg, enable_mask,
                           on_off ? enable_mask : 0);
}

static int meson_sar_adc_hw_enable(struct iio_dev *indio_dev)
{
        struct meson_sar_adc_priv *priv = iio_priv(indio_dev);
        int ret;
        u32 regval;

        ret = meson_sar_adc_lock(indio_dev);
        if (ret)
                goto err_lock;

        ret = regulator_enable(priv->vref);
        if (ret < 0) {
                dev_err(indio_dev->dev.parent,
                        "failed to enable vref regulator\n");
                goto err_vref;
        }

        ret = clk_prepare_enable(priv->core_clk);
        if (ret) {
                dev_err(indio_dev->dev.parent, "failed to enable core clk\n");
                goto err_core_clk;
        }

        regval = FIELD_PREP(MESON_SAR_ADC_REG0_FIFO_CNT_IRQ_MASK, 1);
        regmap_update_bits(priv->regmap, MESON_SAR_ADC_REG0,
                           MESON_SAR_ADC_REG0_FIFO_CNT_IRQ_MASK, regval);

        meson_sar_adc_set_bandgap(indio_dev, true);

        regmap_update_bits(priv->regmap, MESON_SAR_ADC_REG3,
                           MESON_SAR_ADC_REG3_ADC_EN,
                           MESON_SAR_ADC_REG3_ADC_EN);

        udelay(5);

        ret = clk_prepare_enable(priv->adc_clk);
        if (ret) {
                dev_err(indio_dev->dev.parent, "failed to enable adc clk\n");
                goto err_adc_clk;
        }

        meson_sar_adc_unlock(indio_dev);

        return 0;

err_adc_clk:
        regmap_update_bits(priv->regmap, MESON_SAR_ADC_REG3,
                           MESON_SAR_ADC_REG3_ADC_EN, 0);
        meson_sar_adc_set_bandgap(indio_dev, false);
        clk_disable_unprepare(priv->core_clk);
err_core_clk:
        regulator_disable(priv->vref);
err_vref:
        meson_sar_adc_unlock(indio_dev);
err_lock:
        return ret;
}

static int meson_sar_adc_hw_disable(struct iio_dev *indio_dev)
{
        struct meson_sar_adc_priv *priv = iio_priv(indio_dev);
        int ret;

        ret = meson_sar_adc_lock(indio_dev);
        if (ret)
                return ret;

        clk_disable_unprepare(priv->adc_clk);

        regmap_update_bits(priv->regmap, MESON_SAR_ADC_REG3,
                           MESON_SAR_ADC_REG3_ADC_EN, 0);

        meson_sar_adc_set_bandgap(indio_dev, false);

        clk_disable_unprepare(priv->core_clk);

        regulator_disable(priv->vref);

        meson_sar_adc_unlock(indio_dev);

        return 0;
}

static irqreturn_t meson_sar_adc_irq(int irq, void *data)
{
        struct iio_dev *indio_dev = data;
        struct meson_sar_adc_priv *priv = iio_priv(indio_dev);
        unsigned int cnt, threshold;
        u32 regval;

        regmap_read(priv->regmap, MESON_SAR_ADC_REG0, &regval);
        cnt = FIELD_GET(MESON_SAR_ADC_REG0_FIFO_COUNT_MASK, regval);
        threshold = FIELD_GET(MESON_SAR_ADC_REG0_FIFO_CNT_IRQ_MASK, regval);

        if (cnt < threshold)
                return IRQ_NONE;

        complete(&priv->done);

        return IRQ_HANDLED;
}

static int meson_sar_adc_calib(struct iio_dev *indio_dev)
{
        struct meson_sar_adc_priv *priv = iio_priv(indio_dev);
        int ret, nominal0, nominal1, value0, value1;

        /* use points 25% and 75% for calibration */
        nominal0 = (1 << priv->data->param->resolution) / 4;
        nominal1 = (1 << priv->data->param->resolution) * 3 / 4;

        meson_sar_adc_set_chan7_mux(indio_dev, CHAN7_MUX_VDD_DIV4);
        usleep_range(10, 20);
        ret = meson_sar_adc_get_sample(indio_dev,
                                       &meson_sar_adc_iio_channels[7],
                                       MEAN_AVERAGING, EIGHT_SAMPLES, &value0);
        if (ret < 0)
                goto out;

        meson_sar_adc_set_chan7_mux(indio_dev, CHAN7_MUX_VDD_MUL3_DIV4);
        usleep_range(10, 20);
        ret = meson_sar_adc_get_sample(indio_dev,
                                       &meson_sar_adc_iio_channels[7],
                                       MEAN_AVERAGING, EIGHT_SAMPLES, &value1);
        if (ret < 0)
                goto out;

        if (value1 <= value0) {
                ret = -EINVAL;
                goto out;
        }

        priv->calibscale = div_s64((nominal1 - nominal0) * (s64)MILLION,
                                   value1 - value0);
        priv->calibbias = nominal0 - div_s64((s64)value0 * priv->calibscale,
                                             MILLION);
        ret = 0;
out:
        meson_sar_adc_set_chan7_mux(indio_dev, CHAN7_MUX_CH7_INPUT);

        return ret;
}

static const struct iio_info meson_sar_adc_iio_info = {
        .read_raw = meson_sar_adc_iio_info_read_raw,
};

static const struct meson_sar_adc_param meson_sar_adc_meson8_param = {
        .has_bl30_integration = false,
        .clock_rate = 1150000,
        .bandgap_reg = MESON_SAR_ADC_DELTA_10,
        .regmap_config = &meson_sar_adc_regmap_config_meson8,
        .resolution = 10,
};

static const struct meson_sar_adc_param meson_sar_adc_gxbb_param = {
        .has_bl30_integration = true,
        .clock_rate = 1200000,
        .bandgap_reg = MESON_SAR_ADC_REG11,
        .regmap_config = &meson_sar_adc_regmap_config_gxbb,
        .resolution = 10,
};

static const struct meson_sar_adc_param meson_sar_adc_gxl_param = {
        .has_bl30_integration = true,
        .clock_rate = 1200000,
        .bandgap_reg = MESON_SAR_ADC_REG11,
        .regmap_config = &meson_sar_adc_regmap_config_gxbb,
        .resolution = 12,
};

static const struct meson_sar_adc_data meson_sar_adc_meson8_data = {
        .param = &meson_sar_adc_meson8_param,
        .name = "meson-meson8-saradc",
};

static const struct meson_sar_adc_data meson_sar_adc_meson8b_data = {
        .param = &meson_sar_adc_meson8_param,
        .name = "meson-meson8b-saradc",
};

static const struct meson_sar_adc_data meson_sar_adc_meson8m2_data = {
        .param = &meson_sar_adc_meson8_param,
        .name = "meson-meson8m2-saradc",
};

static const struct meson_sar_adc_data meson_sar_adc_gxbb_data = {
        .param = &meson_sar_adc_gxbb_param,
        .name = "meson-gxbb-saradc",
};

static const struct meson_sar_adc_data meson_sar_adc_gxl_data = {
        .param = &meson_sar_adc_gxl_param,
        .name = "meson-gxl-saradc",
};

static const struct meson_sar_adc_data meson_sar_adc_gxm_data = {
        .param = &meson_sar_adc_gxl_param,
        .name = "meson-gxm-saradc",
};

static const struct meson_sar_adc_data meson_sar_adc_axg_data = {
        .param = &meson_sar_adc_gxl_param,
        .name = "meson-axg-saradc",
};

static const struct of_device_id meson_sar_adc_of_match[] = {
        {
                .compatible = "amlogic,meson8-saradc",
                .data = &meson_sar_adc_meson8_data,
        },
        {
                .compatible = "amlogic,meson8b-saradc",
                .data = &meson_sar_adc_meson8b_data,
        },
        {
                .compatible = "amlogic,meson8m2-saradc",
                .data = &meson_sar_adc_meson8m2_data,
        },
        {
                .compatible = "amlogic,meson-gxbb-saradc",
                .data = &meson_sar_adc_gxbb_data,
        }, {
                .compatible = "amlogic,meson-gxl-saradc",
                .data = &meson_sar_adc_gxl_data,
        }, {
                .compatible = "amlogic,meson-gxm-saradc",
                .data = &meson_sar_adc_gxm_data,
        }, {
                .compatible = "amlogic,meson-axg-saradc",
                .data = &meson_sar_adc_axg_data,
        },
        {},
};
MODULE_DEVICE_TABLE(of, meson_sar_adc_of_match);

static int meson_sar_adc_probe(struct platform_device *pdev)
{
        struct meson_sar_adc_priv *priv;
        struct iio_dev *indio_dev;
        struct resource *res;
        void __iomem *base;
        const struct of_device_id *match;
        int irq, ret;

        indio_dev = devm_iio_device_alloc(&pdev->dev, sizeof(*priv));
        if (!indio_dev) {
                dev_err(&pdev->dev, "failed allocating iio device\n");
                return -ENOMEM;
        }

        priv = iio_priv(indio_dev);
        init_completion(&priv->done);

        match = of_match_device(meson_sar_adc_of_match, &pdev->dev);
        if (!match) {
                dev_err(&pdev->dev, "failed to match device\n");
                return -ENODEV;
        }

        priv->data = match->data;

        indio_dev->name = priv->data->name;
        indio_dev->dev.parent = &pdev->dev;
        indio_dev->dev.of_node = pdev->dev.of_node;
        indio_dev->modes = INDIO_DIRECT_MODE;
        indio_dev->info = &meson_sar_adc_iio_info;

        indio_dev->channels = meson_sar_adc_iio_channels;
        indio_dev->num_channels = ARRAY_SIZE(meson_sar_adc_iio_channels);

        res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
        base = devm_ioremap_resource(&pdev->dev, res);
        if (IS_ERR(base))
                return PTR_ERR(base);

        priv->regmap = devm_regmap_init_mmio(&pdev->dev, base,
                                             priv->data->param->regmap_config);
        if (IS_ERR(priv->regmap))
                return PTR_ERR(priv->regmap);

        irq = irq_of_parse_and_map(pdev->dev.of_node, 0);
        if (!irq)
                return -EINVAL;

        ret = devm_request_irq(&pdev->dev, irq, meson_sar_adc_irq, IRQF_SHARED,
                               dev_name(&pdev->dev), indio_dev);
        if (ret)
                return ret;

        priv->clkin = devm_clk_get(&pdev->dev, "clkin");
        if (IS_ERR(priv->clkin)) {
                dev_err(&pdev->dev, "failed to get clkin\n");
                return PTR_ERR(priv->clkin);
        }

        priv->core_clk = devm_clk_get(&pdev->dev, "core");
        if (IS_ERR(priv->core_clk)) {
                dev_err(&pdev->dev, "failed to get core clk\n");
                return PTR_ERR(priv->core_clk);
        }

        priv->adc_clk = devm_clk_get(&pdev->dev, "adc_clk");
        if (IS_ERR(priv->adc_clk)) {
                if (PTR_ERR(priv->adc_clk) == -ENOENT) {
                        priv->adc_clk = NULL;
                } else {
                        dev_err(&pdev->dev, "failed to get adc clk\n");
                        return PTR_ERR(priv->adc_clk);
                }
        }

        priv->adc_sel_clk = devm_clk_get(&pdev->dev, "adc_sel");
        if (IS_ERR(priv->adc_sel_clk)) {
                if (PTR_ERR(priv->adc_sel_clk) == -ENOENT) {
                        priv->adc_sel_clk = NULL;
                } else {
                        dev_err(&pdev->dev, "failed to get adc_sel clk\n");
                        return PTR_ERR(priv->adc_sel_clk);
                }
        }

        /* on pre-GXBB SoCs the SAR ADC itself provides the ADC clock: */
        if (!priv->adc_clk) {
                ret = meson_sar_adc_clk_init(indio_dev, base);
                if (ret)
                        return ret;
        }

        priv->vref = devm_regulator_get(&pdev->dev, "vref");
        if (IS_ERR(priv->vref)) {
                dev_err(&pdev->dev, "failed to get vref regulator\n");
                return PTR_ERR(priv->vref);
        }

        priv->calibscale = MILLION;

        ret = meson_sar_adc_init(indio_dev);
        if (ret)
                goto err;

        ret = meson_sar_adc_hw_enable(indio_dev);
        if (ret)
                goto err;

        ret = meson_sar_adc_calib(indio_dev);
        if (ret)
                dev_warn(&pdev->dev, "calibration failed\n");

        platform_set_drvdata(pdev, indio_dev);

        ret = iio_device_register(indio_dev);
        if (ret)
                goto err_hw;

        return 0;

err_hw:
        meson_sar_adc_hw_disable(indio_dev);
err:
        return ret;
}

static int meson_sar_adc_remove(struct platform_device *pdev)
{
        struct iio_dev *indio_dev = platform_get_drvdata(pdev);

        iio_device_unregister(indio_dev);

        return meson_sar_adc_hw_disable(indio_dev);
}

static int __maybe_unused meson_sar_adc_suspend(struct device *dev)
{
        struct iio_dev *indio_dev = dev_get_drvdata(dev);

        return meson_sar_adc_hw_disable(indio_dev);
}

static int __maybe_unused meson_sar_adc_resume(struct device *dev)
{
        struct iio_dev *indio_dev = dev_get_drvdata(dev);

        return meson_sar_adc_hw_enable(indio_dev);
}

static SIMPLE_DEV_PM_OPS(meson_sar_adc_pm_ops,
                         meson_sar_adc_suspend, meson_sar_adc_resume);

static struct platform_driver meson_sar_adc_driver = {
        .probe          = meson_sar_adc_probe,
        .remove         = meson_sar_adc_remove,
        .driver         = {
                .name   = "meson-saradc",
                .of_match_table = meson_sar_adc_of_match,
                .pm = &meson_sar_adc_pm_ops,
        },
};

module_platform_driver(meson_sar_adc_driver);

MODULE_AUTHOR("Martin Blumenstingl <martin.blumenstingl@googlemail.com>");
MODULE_DESCRIPTION("Amlogic Meson SAR ADC driver");
MODULE_LICENSE("GPL v2");