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    Subject[PATCH v5 5/9] iio: adc: mcp3911: add support for buffers
    Date
    Add support for buffers to make the driver fit for more usecases.

    Signed-off-by: Marcus Folkesson <marcus.folkesson@gmail.com>
    Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
    ---
    drivers/iio/adc/Kconfig | 2 +
    drivers/iio/adc/mcp3911.c | 102 +++++++++++++++++++++++++++++++++++---
    2 files changed, 97 insertions(+), 7 deletions(-)

    diff --git a/drivers/iio/adc/Kconfig b/drivers/iio/adc/Kconfig
    index 7fe5930891e0..3b5db59f3931 100644
    --- a/drivers/iio/adc/Kconfig
    +++ b/drivers/iio/adc/Kconfig
    @@ -718,6 +718,8 @@ config MCP3422
    config MCP3911
    tristate "Microchip Technology MCP3911 driver"
    depends on SPI
    + select IIO_BUFFER
    + select IIO_TRIGGERED_BUFFER
    help
    Say yes here to build support for Microchip Technology's MCP3911
    analog to digital converter.
    diff --git a/drivers/iio/adc/mcp3911.c b/drivers/iio/adc/mcp3911.c
    index 29d73b847f5f..87ab7e24ab08 100644
    --- a/drivers/iio/adc/mcp3911.c
    +++ b/drivers/iio/adc/mcp3911.c
    @@ -5,16 +5,24 @@
    * Copyright (C) 2018 Marcus Folkesson <marcus.folkesson@gmail.com>
    * Copyright (C) 2018 Kent Gustavsson <kent@minoris.se>
    */
    +#include <linux/bitfield.h>
    +#include <linux/bits.h>
    #include <linux/clk.h>
    #include <linux/delay.h>
    #include <linux/err.h>
    #include <linux/iio/iio.h>
    +#include <linux/iio/buffer.h>
    +#include <linux/iio/triggered_buffer.h>
    +#include <linux/iio/trigger_consumer.h>
    +#include <linux/iio/trigger.h>
    #include <linux/module.h>
    #include <linux/mod_devicetable.h>
    #include <linux/property.h>
    #include <linux/regulator/consumer.h>
    #include <linux/spi/spi.h>

    +#include <asm/unaligned.h>
    +
    #define MCP3911_REG_CHANNEL0 0x00
    #define MCP3911_REG_CHANNEL1 0x03
    #define MCP3911_REG_MOD 0x06
    @@ -22,6 +30,7 @@
    #define MCP3911_REG_GAIN 0x09

    #define MCP3911_REG_STATUSCOM 0x0a
    +#define MCP3911_STATUSCOM_READ GENMASK(7, 6)
    #define MCP3911_STATUSCOM_CH1_24WIDTH BIT(4)
    #define MCP3911_STATUSCOM_CH0_24WIDTH BIT(3)
    #define MCP3911_STATUSCOM_EN_OFFCAL BIT(2)
    @@ -54,6 +63,13 @@ struct mcp3911 {
    struct regulator *vref;
    struct clk *clki;
    u32 dev_addr;
    + struct {
    + u32 channels[MCP3911_NUM_CHANNELS];
    + s64 ts __aligned(8);
    + } scan;
    +
    + u8 tx_buf __aligned(IIO_DMA_MINALIGN);
    + u8 rx_buf[MCP3911_NUM_CHANNELS * 3];
    };

    static int mcp3911_read(struct mcp3911 *adc, u8 reg, u32 *val, u8 len)
    @@ -196,16 +212,68 @@ static int mcp3911_write_raw(struct iio_dev *indio_dev,
    .type = IIO_VOLTAGE, \
    .indexed = 1, \
    .channel = idx, \
    + .scan_index = idx, \
    .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) | \
    BIT(IIO_CHAN_INFO_OFFSET) | \
    BIT(IIO_CHAN_INFO_SCALE), \
    + .scan_type = { \
    + .sign = 's', \
    + .realbits = 24, \
    + .storagebits = 32, \
    + .endianness = IIO_BE, \
    + }, \
    }

    static const struct iio_chan_spec mcp3911_channels[] = {
    MCP3911_CHAN(0),
    MCP3911_CHAN(1),
    + IIO_CHAN_SOFT_TIMESTAMP(2),
    };

    +static irqreturn_t mcp3911_trigger_handler(int irq, void *p)
    +{
    + struct iio_poll_func *pf = p;
    + struct iio_dev *indio_dev = pf->indio_dev;
    + struct mcp3911 *adc = iio_priv(indio_dev);
    + struct spi_transfer xfer[] = {
    + {
    + .tx_buf = &adc->tx_buf,
    + .len = 1,
    + }, {
    + .rx_buf = adc->rx_buf,
    + .len = sizeof(adc->rx_buf),
    + },
    + };
    +
    + int scan_index;
    + int i = 0;
    + int ret;
    +
    + mutex_lock(&adc->lock);
    + adc->tx_buf = MCP3911_REG_READ(MCP3911_CHANNEL(0), adc->dev_addr);
    + ret = spi_sync_transfer(adc->spi, xfer, ARRAY_SIZE(xfer));
    + if (ret < 0) {
    + dev_warn(&adc->spi->dev,
    + "failed to get conversion data\n");
    + goto out;
    + }
    +
    + for_each_set_bit(scan_index, indio_dev->active_scan_mask,
    + indio_dev->masklength) {
    + const struct iio_chan_spec *scan_chan = &indio_dev->channels[scan_index];
    +
    + adc->scan.channels[i] = get_unaligned_be24(&adc->rx_buf[scan_chan->channel * 3]);
    + i++;
    + }
    + iio_push_to_buffers_with_timestamp(indio_dev, &adc->scan,
    + iio_get_time_ns(indio_dev));
    +out:
    + mutex_unlock(&adc->lock);
    + iio_trigger_notify_done(indio_dev->trig);
    +
    + return IRQ_HANDLED;
    +}
    +
    static const struct iio_info mcp3911_info = {
    .read_raw = mcp3911_read_raw,
    .write_raw = mcp3911_write_raw,
    @@ -214,7 +282,7 @@ static const struct iio_info mcp3911_info = {
    static int mcp3911_config(struct mcp3911 *adc)
    {
    struct device *dev = &adc->spi->dev;
    - u32 configreg;
    + u32 regval;
    int ret;

    ret = device_property_read_u32(dev, "microchip,device-addr", &adc->dev_addr);
    @@ -233,29 +301,43 @@ static int mcp3911_config(struct mcp3911 *adc)
    }
    dev_dbg(&adc->spi->dev, "use device address %i\n", adc->dev_addr);

    - ret = mcp3911_read(adc, MCP3911_REG_CONFIG, &configreg, 2);
    + ret = mcp3911_read(adc, MCP3911_REG_CONFIG, &regval, 2);
    if (ret)
    return ret;

    + regval &= ~MCP3911_CONFIG_VREFEXT;
    if (adc->vref) {
    dev_dbg(&adc->spi->dev, "use external voltage reference\n");
    - configreg |= MCP3911_CONFIG_VREFEXT;
    + regval |= FIELD_PREP(MCP3911_CONFIG_VREFEXT, 1);
    } else {
    dev_dbg(&adc->spi->dev,
    "use internal voltage reference (1.2V)\n");
    - configreg &= ~MCP3911_CONFIG_VREFEXT;
    + regval |= FIELD_PREP(MCP3911_CONFIG_VREFEXT, 0);
    }

    + regval &= ~MCP3911_CONFIG_CLKEXT;
    if (adc->clki) {
    dev_dbg(&adc->spi->dev, "use external clock as clocksource\n");
    - configreg |= MCP3911_CONFIG_CLKEXT;
    + regval |= FIELD_PREP(MCP3911_CONFIG_CLKEXT, 1);
    } else {
    dev_dbg(&adc->spi->dev,
    "use crystal oscillator as clocksource\n");
    - configreg &= ~MCP3911_CONFIG_CLKEXT;
    + regval |= FIELD_PREP(MCP3911_CONFIG_CLKEXT, 0);
    }

    - return mcp3911_write(adc, MCP3911_REG_CONFIG, configreg, 2);
    + ret = mcp3911_write(adc, MCP3911_REG_CONFIG, regval, 2);
    + if (ret)
    + return ret;
    +
    + ret = mcp3911_read(adc, MCP3911_REG_STATUSCOM, &regval, 2);
    + if (ret)
    + return ret;
    +
    + /* Address counter incremented, cycle through register types */
    + regval &= ~MCP3911_STATUSCOM_READ;
    + regval |= FIELD_PREP(MCP3911_STATUSCOM_READ, 0x02);
    +
    + return mcp3911_write(adc, MCP3911_REG_STATUSCOM, regval, 2);
    }

    static void mcp3911_cleanup_clock(void *_adc)
    @@ -343,6 +425,12 @@ static int mcp3911_probe(struct spi_device *spi)

    mutex_init(&adc->lock);

    + ret = devm_iio_triggered_buffer_setup(&spi->dev, indio_dev,
    + NULL,
    + mcp3911_trigger_handler, NULL);
    + if (ret)
    + return ret;
    +
    return devm_iio_device_register(&adc->spi->dev, indio_dev);
    }

    --
    2.37.1
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