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    Subject[PATCH v7 5/7] IIO: Ingenic JZ47xx: Add touchscreen mode.
    Date
    The SADC component in JZ47xx SoCs provides support for touchscreen
    operations (pen position and pen down pressure) in single-ended and
    differential modes.

    Of the known hardware to use this controller, GCW Zero and Anbernic RG-350
    utilize the touchscreen mode by having their joystick(s) attached to the
    X/Y positive/negative input pins.
    GCW Zero comes with a single joystick and is sufficiently handled with the
    currently implemented single-ended mode. Support for boards with two
    joysticks, where one is hooked up to Xn/Yn and the other to Xp/Yp channels
    will need to be provided in the future.

    The touchscreen component of SADC takes a significant time to stabilize
    after first receiving the clock and a delay of 50ms has been empirically
    proven to be a safe value before data sampling can begin.

    All the boards which probe this driver have the interrupt provided from
    Device Tree, with no need to handle a case where the IRQ was not provided.

    Signed-off-by: Artur Rojek <contact@artur-rojek.eu>
    Tested-by: Paul Cercueil <paul@crapouillou.net>
    ---

    Changes:

    v2: - improve description of the touchscreen mode,
    - get rid of the unneeded kfifo,
    - drop IIO_BUFFER_CB from Kconfig,
    - remove extended names from the touchscreen channels

    v3: remove unneeded `linux/iio/kfifo_buf.h` include

    v4: clarify irq provider source in the patch description

    v5: no change

    v6: - correct the spelling of Device Tree and IRQ in commit message
    - don't omit trailing commas from initializer lists
    - error check `clk_enable`
    - remove redundant `dev_err` from `platform_get_irq` error check

    v7: no change

    drivers/iio/adc/Kconfig | 1 +
    drivers/iio/adc/ingenic-adc.c | 115 +++++++++++++++++++++++++++++++++-
    2 files changed, 114 insertions(+), 2 deletions(-)

    diff --git a/drivers/iio/adc/Kconfig b/drivers/iio/adc/Kconfig
    index 12bb8b7ca1ff..c3314135fa2a 100644
    --- a/drivers/iio/adc/Kconfig
    +++ b/drivers/iio/adc/Kconfig
    @@ -465,6 +465,7 @@ config INA2XX_ADC
    config INGENIC_ADC
    tristate "Ingenic JZ47xx SoCs ADC driver"
    depends on MIPS || COMPILE_TEST
    + select IIO_BUFFER
    help
    Say yes here to build support for the Ingenic JZ47xx SoCs ADC unit.

    diff --git a/drivers/iio/adc/ingenic-adc.c b/drivers/iio/adc/ingenic-adc.c
    index 0eee4b4fb96c..49226d8fd8f6 100644
    --- a/drivers/iio/adc/ingenic-adc.c
    +++ b/drivers/iio/adc/ingenic-adc.c
    @@ -8,7 +8,9 @@

    #include <dt-bindings/iio/adc/ingenic,adc.h>
    #include <linux/clk.h>
    +#include <linux/iio/buffer.h>
    #include <linux/iio/iio.h>
    +#include <linux/interrupt.h>
    #include <linux/io.h>
    #include <linux/iopoll.h>
    #include <linux/kernel.h>
    @@ -20,6 +22,8 @@
    #define JZ_ADC_REG_CFG 0x04
    #define JZ_ADC_REG_CTRL 0x08
    #define JZ_ADC_REG_STATUS 0x0c
    +#define JZ_ADC_REG_ADSAME 0x10
    +#define JZ_ADC_REG_ADWAIT 0x14
    #define JZ_ADC_REG_ADTCH 0x18
    #define JZ_ADC_REG_ADBDAT 0x1c
    #define JZ_ADC_REG_ADSDAT 0x20
    @@ -28,6 +32,9 @@
    #define JZ_ADC_REG_ENABLE_PD BIT(7)
    #define JZ_ADC_REG_CFG_AUX_MD (BIT(0) | BIT(1))
    #define JZ_ADC_REG_CFG_BAT_MD BIT(4)
    +#define JZ_ADC_REG_CFG_PULL_UP(n) ((n) << 16)
    +#define JZ_ADC_REG_CFG_SAMPLE_NUM(n) ((n) << 10)
    +#define JZ_ADC_REG_CFG_TOUCH_OPS_MASK (BIT(31) | GENMASK(23, 10))
    #define JZ_ADC_REG_ADCLK_CLKDIV_LSB 0
    #define JZ4725B_ADC_REG_ADCLK_CLKDIV10US_LSB 16
    #define JZ4770_ADC_REG_ADCLK_CLKDIV10US_LSB 8
    @@ -44,6 +51,14 @@
    #define JZ4770_ADC_BATTERY_VREF 6600
    #define JZ4770_ADC_BATTERY_VREF_BITS 12

    +#define JZ_ADC_IRQ_AUX BIT(0)
    +#define JZ_ADC_IRQ_BATTERY BIT(1)
    +#define JZ_ADC_IRQ_TOUCH BIT(2)
    +#define JZ_ADC_IRQ_PEN_DOWN BIT(3)
    +#define JZ_ADC_IRQ_PEN_UP BIT(4)
    +#define JZ_ADC_IRQ_PEN_DOWN_SLEEP BIT(5)
    +#define JZ_ADC_IRQ_SLEEP BIT(7)
    +
    struct ingenic_adc;

    struct ingenic_adc_soc_data {
    @@ -428,6 +443,28 @@ static const struct iio_info ingenic_adc_info = {
    };

    static const struct iio_chan_spec ingenic_channels[] = {
    + {
    + .type = IIO_POSITIONRELATIVE,
    + .indexed = 1,
    + .channel = INGENIC_ADC_TOUCH_XP,
    + .scan_index = 0,
    + .scan_type = {
    + .sign = 'u',
    + .realbits = 12,
    + .storagebits = 16,
    + },
    + },
    + {
    + .type = IIO_POSITIONRELATIVE,
    + .indexed = 1,
    + .channel = INGENIC_ADC_TOUCH_YP,
    + .scan_index = 1,
    + .scan_type = {
    + .sign = 'u',
    + .realbits = 12,
    + .storagebits = 16,
    + },
    + },
    {
    .extend_name = "aux",
    .type = IIO_VOLTAGE,
    @@ -435,6 +472,7 @@ static const struct iio_chan_spec ingenic_channels[] = {
    BIT(IIO_CHAN_INFO_SCALE),
    .indexed = 1,
    .channel = INGENIC_ADC_AUX,
    + .scan_index = -1,
    },
    {
    .extend_name = "battery",
    @@ -445,6 +483,7 @@ static const struct iio_chan_spec ingenic_channels[] = {
    BIT(IIO_CHAN_INFO_SCALE),
    .indexed = 1,
    .channel = INGENIC_ADC_BATTERY,
    + .scan_index = -1,
    },
    { /* Must always be last in the array. */
    .extend_name = "aux2",
    @@ -453,16 +492,76 @@ static const struct iio_chan_spec ingenic_channels[] = {
    BIT(IIO_CHAN_INFO_SCALE),
    .indexed = 1,
    .channel = INGENIC_ADC_AUX2,
    + .scan_index = -1,
    },
    };

    +static int ingenic_adc_buffer_enable(struct iio_dev *iio_dev)
    +{
    + struct ingenic_adc *adc = iio_priv(iio_dev);
    + int ret;
    +
    + ret = clk_enable(adc->clk);
    + if (ret) {
    + dev_err(iio_dev->dev.parent, "Failed to enable clock: %d\n",
    + ret);
    + return ret;
    + }
    +
    + /* It takes significant time for the touchscreen hw to stabilize. */
    + msleep(50);
    + ingenic_adc_set_config(adc, JZ_ADC_REG_CFG_TOUCH_OPS_MASK,
    + JZ_ADC_REG_CFG_SAMPLE_NUM(4) |
    + JZ_ADC_REG_CFG_PULL_UP(4));
    + writew(80, adc->base + JZ_ADC_REG_ADWAIT);
    + writew(2, adc->base + JZ_ADC_REG_ADSAME);
    + writeb((u8)~JZ_ADC_IRQ_TOUCH, adc->base + JZ_ADC_REG_CTRL);
    + writel(0, adc->base + JZ_ADC_REG_ADTCH);
    + ingenic_adc_enable(adc, 2, true);
    +
    + return 0;
    +}
    +
    +static int ingenic_adc_buffer_disable(struct iio_dev *iio_dev)
    +{
    + struct ingenic_adc *adc = iio_priv(iio_dev);
    +
    + ingenic_adc_enable(adc, 2, false);
    + writeb(0xff, adc->base + JZ_ADC_REG_CTRL);
    + writeb(0xff, adc->base + JZ_ADC_REG_STATUS);
    + ingenic_adc_set_config(adc, JZ_ADC_REG_CFG_TOUCH_OPS_MASK, 0);
    + writew(0, adc->base + JZ_ADC_REG_ADSAME);
    + writew(0, adc->base + JZ_ADC_REG_ADWAIT);
    + clk_disable(adc->clk);
    +
    + return 0;
    +}
    +
    +static const struct iio_buffer_setup_ops ingenic_buffer_setup_ops = {
    + .postenable = &ingenic_adc_buffer_enable,
    + .predisable = &ingenic_adc_buffer_disable
    +};
    +
    +static irqreturn_t ingenic_adc_irq(int irq, void *data)
    +{
    + struct iio_dev *iio_dev = data;
    + struct ingenic_adc *adc = iio_priv(iio_dev);
    + u32 tdat;
    +
    + tdat = readl(adc->base + JZ_ADC_REG_ADTCH);
    + iio_push_to_buffers(iio_dev, &tdat);
    + writeb(JZ_ADC_IRQ_TOUCH, adc->base + JZ_ADC_REG_STATUS);
    +
    + return IRQ_HANDLED;
    +}
    +
    static int ingenic_adc_probe(struct platform_device *pdev)
    {
    struct device *dev = &pdev->dev;
    struct iio_dev *iio_dev;
    struct ingenic_adc *adc;
    const struct ingenic_adc_soc_data *soc_data;
    - int ret;
    + int irq, ret;

    soc_data = device_get_match_data(dev);
    if (!soc_data)
    @@ -477,6 +576,17 @@ static int ingenic_adc_probe(struct platform_device *pdev)
    mutex_init(&adc->aux_lock);
    adc->soc_data = soc_data;

    + irq = platform_get_irq(pdev, 0);
    + if (irq < 0)
    + return irq;
    +
    + ret = devm_request_irq(dev, irq, ingenic_adc_irq, 0,
    + dev_name(dev), iio_dev);
    + if (ret < 0) {
    + dev_err(dev, "Failed to request irq: %d\n", ret);
    + return ret;
    + }
    +
    adc->base = devm_platform_ioremap_resource(pdev, 0);
    if (IS_ERR(adc->base))
    return PTR_ERR(adc->base);
    @@ -516,7 +626,8 @@ static int ingenic_adc_probe(struct platform_device *pdev)

    iio_dev->dev.parent = dev;
    iio_dev->name = "jz-adc";
    - iio_dev->modes = INDIO_DIRECT_MODE;
    + iio_dev->modes = INDIO_DIRECT_MODE | INDIO_BUFFER_SOFTWARE;
    + iio_dev->setup_ops = &ingenic_buffer_setup_ops;
    iio_dev->channels = ingenic_channels;
    iio_dev->num_channels = ARRAY_SIZE(ingenic_channels);
    /* Remove AUX2 from the list of supported channels. */
    --
    2.26.2
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