Re: [PATCH v2] iio: exynos-adc: add experimental touchscreen support

Dmitry Torokhov
2014-07-22T18:09:04Z

On Tue, Jul 22, 2014 at 03:03:12PM +0200, Arnd Bergmann wrote:
> This adds support for the touchscreen on Samsung s3c64xx.
> The driver is completely untested but shows roughly how
> it could be done, following the example of the at91 driver.
>
> Open questions include:
>
> - compared to the old plat-samsung/adc driver, there is
> no support for prioritizing ts over other clients, nor
> for oversampling. From my reading of the code, the
> priorities didn't actually have any effect at all, but
> the oversampling might be needed. Maybe the original
> authors have some insight.
>
> - We probably need to add support for platform_data as well,
> I've skipped this so far.
>
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
> ---
> This should address all previous comments, and I've also added
> a write to ADC_V1_DLY() as the old driver does.
>
> diff --git a/Documentation/devicetree/bindings/arm/samsung/exynos-adc.txt b/Documentation/devicetree/bindings/arm/samsung/exynos-adc.txt
> index cad81b666a67..ba30836c73cb 100644
> --- a/Documentation/devicetree/bindings/arm/samsung/exynos-adc.txt
> +++ b/Documentation/devicetree/bindings/arm/samsung/exynos-adc.txt
> @@ -43,6 +43,10 @@ Required properties:
> and compatible ADC block)
> - vdd-supply VDD input supply.
>
> +Optional properties:
> +- has-touchscreen: If present, indicates that a touchscreen is
> + connected an usable.
> +
> Note: child nodes can be added for auto probing from device tree.
>
> Example: adding device info in dtsi file
> diff --git a/drivers/iio/adc/exynos_adc.c b/drivers/iio/adc/exynos_adc.c
> index 420c5cda09c3..3b684a117b9c 100644
> --- a/drivers/iio/adc/exynos_adc.c
> +++ b/drivers/iio/adc/exynos_adc.c
> @@ -34,6 +34,7 @@
> #include <linux/regulator/consumer.h>
> #include <linux/of_platform.h>
> #include <linux/err.h>
> +#include <linux/input.h>
>
> #include <linux/iio/iio.h>
> #include <linux/iio/machine.h>
> @@ -66,6 +67,9 @@
>
> #define ADC_S3C2410_CON_SELMUX(x) (((x)&0x7)<<3)
>
> +/* touch screen always uses channel 0 */
> +#define ADC_S3C2410_MUX_TS 0
> +
> /* ADCTSC Register Bits */
> #define ADC_S3C2443_TSC_UD_SEN (1u << 8)
> #define ADC_S3C2410_TSC_YM_SEN (1u << 7)
> @@ -103,24 +107,32 @@
>
> /* Bit definitions common for ADC_V1 and ADC_V2 */
> #define ADC_CON_EN_START (1u << 0)
> +#define ADC_DATX_PRESSED (1u << 15)
> #define ADC_DATX_MASK 0xFFF
> +#define ADC_DATY_MASK 0xFFF
>
> #define EXYNOS_ADC_TIMEOUT (msecs_to_jiffies(100))
>
> struct exynos_adc {
> struct exynos_adc_data *data;
> struct device *dev;
> + struct input_dev *input;
> void __iomem *regs;
> void __iomem *enable_reg;
> struct clk *clk;
> struct clk *sclk;
> unsigned int irq;
> + unsigned int tsirq;
> struct regulator *vdd;
>
> struct completion completion;
>
> u32 value;
> unsigned int version;
> +
> + bool read_ts;
> + u32 ts_x;
> + u32 ts_y;
> };
>
> struct exynos_adc_data {
> @@ -205,6 +217,9 @@ static void exynos_adc_v1_init_hw(struct exynos_adc *info)
> /* Enable 12-bit ADC resolution */
> con1 |= ADC_V1_CON_RES;
> writel(con1, ADC_V1_CON(info->regs));
> +
> + /* set default touchscreen delay */
> + writel(10000, ADC_V1_DLY(info->regs));
> }
>
> static void exynos_adc_v1_exit_hw(struct exynos_adc *info)
> @@ -390,12 +405,54 @@ static int exynos_read_raw(struct iio_dev *indio_dev,
> return ret;
> }
>
> +static int exynos_read_s3c64xx_ts(struct iio_dev *indio_dev, int *x, int *y)
> +{
> + struct exynos_adc *info = iio_priv(indio_dev);
> + unsigned long timeout;
> + int ret;
> +
> + mutex_lock(&indio_dev->mlock);
> + info->read_ts = true;
> +
> + reinit_completion(&info->completion);
> +
> + writel(ADC_S3C2410_TSC_PULL_UP_DISABLE | ADC_TSC_AUTOPST,
> + ADC_V1_TSC(info->regs));
> +
> + /* Select the ts channel to be used and Trigger conversion */
> + info->data->start_conv(info, ADC_S3C2410_MUX_TS);
> +
> + timeout = wait_for_completion_timeout
> + (&info->completion, EXYNOS_ADC_TIMEOUT);
> + if (timeout == 0) {
> + dev_warn(&indio_dev->dev, "Conversion timed out! Resetting\n");
> + if (info->data->init_hw)
> + info->data->init_hw(info);
> + ret = -ETIMEDOUT;
> + } else {
> + *x = info->ts_x;
> + *y = info->ts_y;
> + ret = 0;
> + }
> +
> + info->read_ts = false;
> + mutex_unlock(&indio_dev->mlock);
> +
> + return ret;
> +}
> +
> static irqreturn_t exynos_adc_isr(int irq, void *dev_id)
> {
> struct exynos_adc *info = (struct exynos_adc *)dev_id;
>
> /* Read value */
> - info->value = readl(ADC_V1_DATX(info->regs)) & ADC_DATX_MASK;
> + if (info->read_ts) {
> + info->ts_x = readl(ADC_V1_DATX(info->regs));
> + info->ts_y = readl(ADC_V1_DATY(info->regs));
> + writel(ADC_TSC_WAIT4INT | ADC_S3C2443_TSC_UD_SEN, ADC_V1_TSC(info->regs));
> + } else {
> + info->value = readl(ADC_V1_DATX(info->regs)) & ADC_DATX_MASK;
> + }
>
> /* clear irq */
> if (info->data->clear_irq)
> @@ -406,6 +463,46 @@ static irqreturn_t exynos_adc_isr(int irq, void *dev_id)
> return IRQ_HANDLED;
> }
>
> +/*
> + * Here we (ab)use a threaded interrupt handler to stay running
> + * for as long as the touchscreen remains pressed, we report
> + * a new event with the latest data and then sleep until the
> + * next timer tick. This mirrors the behavior of the old
> + * driver, with much less code.
> + */
> +static irqreturn_t exynos_ts_isr(int irq, void *dev_id)
> +{
> + struct exynos_adc *info = dev_id;
> + struct iio_dev *dev = dev_get_drvdata(info->dev);
> + u32 x, y;
> + bool pressed;
> + int ret;
> +
> + while (info->input->users) {
> + ret = exynos_read_s3c64xx_ts(dev, &x, &y);
> + if (ret == -ETIMEDOUT)
> + break;
> +
> + pressed = x & y & ADC_DATX_PRESSED;
> + if (!pressed) {
> + input_report_key(info->input, BTN_TOUCH, 0);
> + input_sync(info->input);
> + break;
> + }
> +
> + input_report_abs(info->input, ABS_X, x & ADC_DATX_MASK);
> + input_report_abs(info->input, ABS_Y, y & ADC_DATY_MASK);
> + input_report_key(info->input, BTN_TOUCH, 1);
> + input_sync(info->input);
> +
> + msleep(1);
> + };
> +
> + writel(0, ADC_V1_CLRINTPNDNUP(info->regs));
> +
> + return IRQ_HANDLED;
> +}
> +
> static int exynos_adc_reg_access(struct iio_dev *indio_dev,
> unsigned reg, unsigned writeval,
> unsigned *readval)
> @@ -457,12 +554,66 @@ static int exynos_adc_remove_devices(struct device *dev, void *c)
> return 0;
> }
>
> +static int exynos_adc_ts_open(struct input_dev *dev)
> +{
> + struct exynos_adc *info = input_get_drvdata(dev);
> +
> + enable_irq(info->tsirq);
> +
> + return 0;
> +}
> +
> +static void exynos_adc_ts_close(struct input_dev *dev)
> +{
> + struct exynos_adc *info = input_get_drvdata(dev);
> +
> + disable_irq(info->tsirq);
> +}
> +
> +static int exynos_adc_ts_init(struct exynos_adc *info)
> +{
> + int ret;
> +
> + if (info->tsirq <= 0)
> + return -ENODEV;
> +
> + info->input = input_allocate_device();
> + if (!info->input)
> + return -ENOMEM;
> +
> + info->input->evbit[0] = BIT_MASK(EV_KEY) | BIT_MASK(EV_ABS);
> + info->input->keybit[BIT_WORD(BTN_TOUCH)] = BIT_MASK(BTN_TOUCH);
> +
> + input_set_abs_params(info->input, ABS_X, 0, 0x3FF, 0, 0);
> + input_set_abs_params(info->input, ABS_Y, 0, 0x3FF, 0, 0);
> +
> + info->input->name = "S3C24xx TouchScreen";
> + info->input->id.bustype = BUS_HOST;
> + info->input->open = exynos_adc_ts_open;
> + info->input->close = exynos_adc_ts_close;
> +
> + input_set_drvdata(info->input, info);
> +
> + ret = input_register_device(info->input);
> + if (ret)
> + input_free_device(info->input);
> +
> + disable_irq(info->tsirq);
> + ret = request_threaded_irq(info->tsirq, NULL, exynos_ts_isr,
> + 0, "touchscreen", info);
> + if (ret)
> + input_unregister_device(info->input);
> +
> + return ret;
> +}
> +
> static int exynos_adc_probe(struct platform_device *pdev)
> {
> struct exynos_adc *info = NULL;
> struct device_node *np = pdev->dev.of_node;
> struct iio_dev *indio_dev = NULL;
> struct resource *mem;
> + bool has_ts = false;
> int ret = -ENODEV;
> int irq;
>
> @@ -498,8 +649,14 @@ static int exynos_adc_probe(struct platform_device *pdev)
> dev_err(&pdev->dev, "no irq resource?\n");
> return irq;
> }
> -
> info->irq = irq;
> +
> + irq = platform_get_irq(pdev, 1);
> + if (irq == -EPROBE_DEFER)
> + return irq;
> +
> + info->tsirq = irq;
> +
> info->dev = &pdev->dev;
>
> init_completion(&info->completion);
> @@ -565,6 +722,15 @@ static int exynos_adc_probe(struct platform_device *pdev)
> if (info->data->init_hw)
> info->data->init_hw(info);
>
> + /* leave out any TS related code if unreachable */
> + if (IS_BUILTIN(CONFIG_INPUT) ||
> + (IS_MODULE(CONFIG_INPUT) && config_enabled(MODULE)))

This is ugly... We need IS_SUBSYSTEM_AVAILABLE() wrapper for this...

Anyway,

Acked-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

> + has_ts = of_property_read_bool(pdev->dev.of_node, "has-touchscreen");
> + if (has_ts)
> + ret = exynos_adc_ts_init(info);
> + if (ret)
> + goto err_iio;
> +
> ret = of_platform_populate(np, exynos_adc_match, NULL, &indio_dev->dev);
> if (ret < 0) {
> dev_err(&pdev->dev, "failed adding child nodes\n");
> @@ -576,6 +742,11 @@ static int exynos_adc_probe(struct platform_device *pdev)
> err_of_populate:
> device_for_each_child(&indio_dev->dev, NULL,
> exynos_adc_remove_devices);
> + if (has_ts) {
> + input_unregister_device(info->input);
> + free_irq(info->tsirq, info);
> + }
> +err_iio:
> iio_device_unregister(indio_dev);
> err_irq:
> free_irq(info->irq, info);
> @@ -595,6 +766,11 @@ static int exynos_adc_remove(struct platform_device *pdev)
> struct iio_dev *indio_dev = platform_get_drvdata(pdev);
> struct exynos_adc *info = iio_priv(indio_dev);
>
> + if (IS_BUILTIN(CONFIG_INPUT) ||
> + (IS_MODULE(CONFIG_INPUT) && config_enabled(MODULE))) {
> + free_irq(info->tsirq, info);
> + input_unregister_device(info->input);
> + }
> device_for_each_child(&indio_dev->dev, NULL,
> exynos_adc_remove_devices);
> iio_device_unregister(indio_dev);
>

--
Dmitry