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

Arnd Bergmann
2014-07-22T13:03:12Z

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-r2nGTMty4D4@public.gmane.org>
---
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)))
+ 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);