iio: adc: at91_adc: Add support for touchscreens without TSMR

Old ADCs, as present on the sam9rl and the sam9g45 don't have a TSMR register
and the touchscreen support should be handled differently.

Signed-off-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>
Acked-by: Jonathan Cameron <jic23@kernel.org>
Signed-off-by: Nicolas Ferre <nicolas.ferre@atmel.com>

3 files changed, 174 insertions, 47 deletions

diff --git a/arch/arm/mach-at91/include/mach/at91_adc.h b/arch/arm/mach-at91/include/mach/at91_adc.h
index c287307b9a3b..7d80396346b2 100644
--- a/arch/arm/mach-at91/include/mach/at91_adc.h
+++ b/arch/arm/mach-at91/include/mach/at91_adc.h
@@ -20,6 +20,9 @@
 #define         AT91_ADC_START          (1 << 1)        /* Start Conversion */
 
 #define AT91_ADC_MR             0x04            /* Mode Register */
+#define         AT91_ADC_TSAMOD         (3 << 0)        /* ADC mode */
+#define         AT91_ADC_TSAMOD_ADC_ONLY_MODE           (0 << 0)        /* ADC Mode */
+#define         AT91_ADC_TSAMOD_TS_ONLY_MODE            (1 << 0)        /* Touch Screen Only Mode */
 #define         AT91_ADC_TRGEN          (1 << 0)        /* Trigger Enable */
 #define         AT91_ADC_TRGSEL         (7 << 1)        /* Trigger Selection */
 #define                 AT91_ADC_TRGSEL_TC0             (0 << 1)
@@ -28,6 +31,7 @@
 #define                 AT91_ADC_TRGSEL_EXTERNAL        (6 << 1)
 #define         AT91_ADC_LOWRES         (1 << 4)        /* Low Resolution */
 #define         AT91_ADC_SLEEP          (1 << 5)        /* Sleep Mode */
+#define         AT91_ADC_PENDET         (1 << 6)        /* Pen contact detection enable */
 #define         AT91_ADC_PRESCAL_9260   (0x3f << 8)     /* Prescalar Rate Selection */
 #define         AT91_ADC_PRESCAL_9G45   (0xff << 8)
 #define                 AT91_ADC_PRESCAL_(x)    ((x) << 8)
@@ -37,6 +41,12 @@
 #define                 AT91_ADC_STARTUP_(x)    ((x) << 16)
 #define         AT91_ADC_SHTIM          (0xf  << 24)    /* Sample & Hold Time */
 #define                 AT91_ADC_SHTIM_(x)      ((x) << 24)
+#define         AT91_ADC_PENDBC         (0x0f << 28)    /* Pen Debounce time */
+#define                 AT91_ADC_PENDBC_(x)     ((x) << 28)
+
+#define AT91_ADC_TSR            0x0C
+#define         AT91_ADC_TSR_SHTIM      (0xf  << 24)    /* Sample & Hold Time */
+#define                 AT91_ADC_TSR_SHTIM_(x)  ((x) << 24)
 
 #define AT91_ADC_CHER           0x10            /* Channel Enable Register */
 #define AT91_ADC_CHDR           0x14            /* Channel Disable Register */
@@ -60,6 +70,8 @@
 #define AT91_ADC_IER            0x24            /* Interrupt Enable Register */
 #define AT91_ADC_IDR            0x28            /* Interrupt Disable Register */
 #define AT91_ADC_IMR            0x2C            /* Interrupt Mask Register */
+#define         AT91RL_ADC_IER_PEN      (1 << 20)
+#define         AT91RL_ADC_IER_NOPEN    (1 << 21)
 #define         AT91_ADC_IER_PEN        (1 << 29)
 #define         AT91_ADC_IER_NOPEN      (1 << 30)
 #define         AT91_ADC_IER_XRDY       (1 << 20)
@@ -102,6 +114,7 @@
 #define         AT91_ADC_TRGR_TRGPER    (0xffff << 16)
 #define                 AT91_ADC_TRGR_TRGPER_(x)        ((x) << 16)
 #define         AT91_ADC_TRGR_TRGMOD    (0x7 << 0)
+#define                 AT91_ADC_TRGR_NONE              (0 << 0)
 #define                 AT91_ADC_TRGR_MOD_PERIOD_TRIG   (5 << 0)
 
 #endif
diff --git a/drivers/iio/adc/at91_adc.c b/drivers/iio/adc/at91_adc.c
index 1beae65aef2c..c0e4206e34e5 100644
--- a/drivers/iio/adc/at91_adc.c
+++ b/drivers/iio/adc/at91_adc.c
@@ -46,6 +46,10 @@
 #define TOUCH_SAMPLE_PERIOD_US          2000    /* 2ms */
 #define TOUCH_PEN_DETECT_DEBOUNCE_US    200
 
+#define MAX_RLPOS_BITS         10
+#define TOUCH_SAMPLE_PERIOD_US_RL      10000   /* 10ms, the SoC can't keep up with 2ms */
+#define TOUCH_SHTIM                    0xa
+
 /**
  * struct at91_adc_reg_desc - Various informations relative to registers
  * @channel_base:       Base offset for the channel data registers
@@ -83,12 +87,6 @@ struct at91_adc_caps {
         struct at91_adc_reg_desc registers;
 };
 
-enum atmel_adc_ts_type {
-        ATMEL_ADC_TOUCHSCREEN_NONE = 0,
-        ATMEL_ADC_TOUCHSCREEN_4WIRE = 4,
-        ATMEL_ADC_TOUCHSCREEN_5WIRE = 5,
-};
-
 struct at91_adc_state {
         struct clk              *adc_clk;
         u16                     *buffer;
@@ -133,6 +131,11 @@ struct at91_adc_state {
 
         u16                     ts_sample_period_val;
         u32                     ts_pressure_threshold;
+        u16                     ts_pendbc;
+
+        bool                    ts_bufferedmeasure;
+        u32                     ts_prev_absx;
+        u32                     ts_prev_absy;
 };
 
 static irqreturn_t at91_adc_trigger_handler(int irq, void *p)
@@ -239,7 +242,72 @@ static int at91_ts_sample(struct at91_adc_state *st)
         return 0;
 }
 
-static irqreturn_t at91_adc_interrupt(int irq, void *private)
+static irqreturn_t at91_adc_rl_interrupt(int irq, void *private)
+{
+        struct iio_dev *idev = private;
+        struct at91_adc_state *st = iio_priv(idev);
+        u32 status = at91_adc_readl(st, st->registers->status_register);
+        unsigned int reg;
+
+        status &= at91_adc_readl(st, AT91_ADC_IMR);
+        if (status & st->registers->drdy_mask)
+                handle_adc_eoc_trigger(irq, idev);
+
+        if (status & AT91RL_ADC_IER_PEN) {
+                /* Disabling pen debounce is required to get a NOPEN irq */
+                reg = at91_adc_readl(st, AT91_ADC_MR);
+                reg &= ~AT91_ADC_PENDBC;
+                at91_adc_writel(st, AT91_ADC_MR, reg);
+
+                at91_adc_writel(st, AT91_ADC_IDR, AT91RL_ADC_IER_PEN);
+                at91_adc_writel(st, AT91_ADC_IER, AT91RL_ADC_IER_NOPEN
+                                | AT91_ADC_EOC(3));
+                /* Set up period trigger for sampling */
+                at91_adc_writel(st, st->registers->trigger_register,
+                        AT91_ADC_TRGR_MOD_PERIOD_TRIG |
+                        AT91_ADC_TRGR_TRGPER_(st->ts_sample_period_val));
+        } else if (status & AT91RL_ADC_IER_NOPEN) {
+                reg = at91_adc_readl(st, AT91_ADC_MR);
+                reg |= AT91_ADC_PENDBC_(st->ts_pendbc) & AT91_ADC_PENDBC;
+                at91_adc_writel(st, AT91_ADC_MR, reg);
+                at91_adc_writel(st, st->registers->trigger_register,
+                        AT91_ADC_TRGR_NONE);
+
+                at91_adc_writel(st, AT91_ADC_IDR, AT91RL_ADC_IER_NOPEN
+                                | AT91_ADC_EOC(3));
+                at91_adc_writel(st, AT91_ADC_IER, AT91RL_ADC_IER_PEN);
+                st->ts_bufferedmeasure = false;
+                input_report_key(st->ts_input, BTN_TOUCH, 0);
+                input_sync(st->ts_input);
+        } else if (status & AT91_ADC_EOC(3)) {
+                /* Conversion finished */
+                if (st->ts_bufferedmeasure) {
+                        /*
+                         * Last measurement is always discarded, since it can
+                         * be erroneous.
+                         * Always report previous measurement
+                         */
+                        input_report_abs(st->ts_input, ABS_X, st->ts_prev_absx);
+                        input_report_abs(st->ts_input, ABS_Y, st->ts_prev_absy);
+                        input_report_key(st->ts_input, BTN_TOUCH, 1);
+                        input_sync(st->ts_input);
+                } else
+                        st->ts_bufferedmeasure = true;
+
+                /* Now make new measurement */
+                st->ts_prev_absx = at91_adc_readl(st, AT91_ADC_CHAN(st, 3))
+                                   << MAX_RLPOS_BITS;
+                st->ts_prev_absx /= at91_adc_readl(st, AT91_ADC_CHAN(st, 2));
+
+                st->ts_prev_absy = at91_adc_readl(st, AT91_ADC_CHAN(st, 1))
+                                   << MAX_RLPOS_BITS;
+                st->ts_prev_absy /= at91_adc_readl(st, AT91_ADC_CHAN(st, 0));
+        }
+
+        return IRQ_HANDLED;
+}
+
+static irqreturn_t at91_adc_9x5_interrupt(int irq, void *private)
 {
         struct iio_dev *idev = private;
         struct at91_adc_state *st = iio_priv(idev);
@@ -672,6 +740,8 @@ static int at91_adc_probe_dt_ts(struct device_node *node,
                 return -EINVAL;
         }
 
+        if (!st->caps->has_tsmr)
+                return 0;
         prop = 0;
         of_property_read_u32(node, "atmel,adc-ts-pressure-threshold", &prop);
         st->ts_pressure_threshold = prop;
@@ -795,6 +865,7 @@ static int at91_adc_probe_pdata(struct at91_adc_state *st,
         st->trigger_number = pdata->trigger_number;
         st->trigger_list = pdata->trigger_list;
         st->registers = &st->caps->registers;
+        st->touchscreen_type = pdata->touchscreen_type;
 
         return 0;
 }
@@ -809,7 +880,10 @@ static int atmel_ts_open(struct input_dev *dev)
 {
         struct at91_adc_state *st = input_get_drvdata(dev);
 
-        at91_adc_writel(st, AT91_ADC_IER, AT91_ADC_IER_PEN);
+        if (st->caps->has_tsmr)
+                at91_adc_writel(st, AT91_ADC_IER, AT91_ADC_IER_PEN);
+        else
+                at91_adc_writel(st, AT91_ADC_IER, AT91RL_ADC_IER_PEN);
         return 0;
 }
 
@@ -817,45 +891,61 @@ static void atmel_ts_close(struct input_dev *dev)
 {
         struct at91_adc_state *st = input_get_drvdata(dev);
 
-        at91_adc_writel(st, AT91_ADC_IDR, AT91_ADC_IER_PEN);
+        if (st->caps->has_tsmr)
+                at91_adc_writel(st, AT91_ADC_IDR, AT91_ADC_IER_PEN);
+        else
+                at91_adc_writel(st, AT91_ADC_IDR, AT91RL_ADC_IER_PEN);
 }
 
 static int at91_ts_hw_init(struct at91_adc_state *st, u32 adc_clk_khz)
 {
-        u32 reg = 0, pendbc;
+        u32 reg = 0;
         int i = 0;
 
-        if (st->touchscreen_type == ATMEL_ADC_TOUCHSCREEN_4WIRE)
-                reg = AT91_ADC_TSMR_TSMODE_4WIRE_PRESS;
-        else
-                reg = AT91_ADC_TSMR_TSMODE_5WIRE;
-
         /* a Pen Detect Debounce Time is necessary for the ADC Touch to avoid
          * pen detect noise.
          * The formula is : Pen Detect Debounce Time = (2 ^ pendbc) / ADCClock
          */
-        pendbc = round_up(TOUCH_PEN_DETECT_DEBOUNCE_US * adc_clk_khz / 1000, 1);
+        st->ts_pendbc = round_up(TOUCH_PEN_DETECT_DEBOUNCE_US * adc_clk_khz /
+                                 1000, 1);
 
-        while (pendbc >> ++i)
+        while (st->ts_pendbc >> ++i)
                 ;       /* Empty! Find the shift offset */
-        if (abs(pendbc - (1 << i)) < abs(pendbc - (1 << (i - 1))))
-                pendbc = i;
+        if (abs(st->ts_pendbc - (1 << i)) < abs(st->ts_pendbc - (1 << (i - 1))))
+                st->ts_pendbc = i;
         else
-                pendbc = i - 1;
+                st->ts_pendbc = i - 1;
 
-        if (st->caps->has_tsmr) {
-                reg |= AT91_ADC_TSMR_TSAV_(st->caps->ts_filter_average)
-                                & AT91_ADC_TSMR_TSAV;
-                reg |= AT91_ADC_TSMR_PENDBC_(pendbc) & AT91_ADC_TSMR_PENDBC;
-                reg |= AT91_ADC_TSMR_NOTSDMA;
-                reg |= AT91_ADC_TSMR_PENDET_ENA;
-                reg |= 0x03 << 8;       /* TSFREQ, need bigger than TSAV */
-
-                at91_adc_writel(st, AT91_ADC_TSMR, reg);
-        } else {
-                /* TODO: for 9g45 which has no TSMR */
+        if (!st->caps->has_tsmr) {
+                reg = at91_adc_readl(st, AT91_ADC_MR);
+                reg |= AT91_ADC_TSAMOD_TS_ONLY_MODE | AT91_ADC_PENDET;
+
+                reg |= AT91_ADC_PENDBC_(st->ts_pendbc) & AT91_ADC_PENDBC;
+                at91_adc_writel(st, AT91_ADC_MR, reg);
+
+                reg = AT91_ADC_TSR_SHTIM_(TOUCH_SHTIM) & AT91_ADC_TSR_SHTIM;
+                at91_adc_writel(st, AT91_ADC_TSR, reg);
+
+                st->ts_sample_period_val = round_up((TOUCH_SAMPLE_PERIOD_US_RL *
+                                                    adc_clk_khz / 1000) - 1, 1);
+
+                return 0;
         }
 
+        if (st->touchscreen_type == ATMEL_ADC_TOUCHSCREEN_4WIRE)
+                reg = AT91_ADC_TSMR_TSMODE_4WIRE_PRESS;
+        else
+                reg = AT91_ADC_TSMR_TSMODE_5WIRE;
+
+        reg |= AT91_ADC_TSMR_TSAV_(st->caps->ts_filter_average)
+               & AT91_ADC_TSMR_TSAV;
+        reg |= AT91_ADC_TSMR_PENDBC_(st->ts_pendbc) & AT91_ADC_TSMR_PENDBC;
+        reg |= AT91_ADC_TSMR_NOTSDMA;
+        reg |= AT91_ADC_TSMR_PENDET_ENA;
+        reg |= 0x03 << 8;       /* TSFREQ, needs to be bigger than TSAV */
+
+        at91_adc_writel(st, AT91_ADC_TSMR, reg);
+
         /* Change adc internal resistor value for better pen detection,
          * default value is 100 kOhm.
          * 0 = 200 kOhm, 1 = 150 kOhm, 2 = 100 kOhm, 3 = 50 kOhm
@@ -864,7 +954,7 @@ static int at91_ts_hw_init(struct at91_adc_state *st, u32 adc_clk_khz)
         at91_adc_writel(st, AT91_ADC_ACR, st->caps->ts_pen_detect_sensitivity
                         & AT91_ADC_ACR_PENDETSENS);
 
-        /* Sample Peroid Time = (TRGPER + 1) / ADCClock */
+        /* Sample Period Time = (TRGPER + 1) / ADCClock */
         st->ts_sample_period_val = round_up((TOUCH_SAMPLE_PERIOD_US *
                         adc_clk_khz / 1000) - 1, 1);
 
@@ -893,17 +983,37 @@ static int at91_ts_register(struct at91_adc_state *st,
         __set_bit(EV_ABS, input->evbit);
         __set_bit(EV_KEY, input->evbit);
         __set_bit(BTN_TOUCH, input->keybit);
-        input_set_abs_params(input, ABS_X, 0, (1 << MAX_POS_BITS) - 1, 0, 0);
-        input_set_abs_params(input, ABS_Y, 0, (1 << MAX_POS_BITS) - 1, 0, 0);
-        input_set_abs_params(input, ABS_PRESSURE, 0, 0xffffff, 0, 0);
+        if (st->caps->has_tsmr) {
+                input_set_abs_params(input, ABS_X, 0, (1 << MAX_POS_BITS) - 1,
+                                     0, 0);
+                input_set_abs_params(input, ABS_Y, 0, (1 << MAX_POS_BITS) - 1,
+                                     0, 0);
+                input_set_abs_params(input, ABS_PRESSURE, 0, 0xffffff, 0, 0);
+        } else {
+                if (st->touchscreen_type != ATMEL_ADC_TOUCHSCREEN_4WIRE) {
+                        dev_err(&pdev->dev,
+                                "This touchscreen controller only support 4 wires\n");
+                        ret = -EINVAL;
+                        goto err;
+                }
+
+                input_set_abs_params(input, ABS_X, 0, (1 << MAX_RLPOS_BITS) - 1,
+                                     0, 0);
+                input_set_abs_params(input, ABS_Y, 0, (1 << MAX_RLPOS_BITS) - 1,
+                                     0, 0);
+        }
 
         st->ts_input = input;
         input_set_drvdata(input, st);
 
         ret = input_register_device(input);
         if (ret)
-                input_free_device(st->ts_input);
+                goto err;
+
+        return ret;
 
+err:
+        input_free_device(st->ts_input);
         return ret;
 }
 
@@ -962,11 +1072,13 @@ static int at91_adc_probe(struct platform_device *pdev)
          */
         at91_adc_writel(st, AT91_ADC_CR, AT91_ADC_SWRST);
         at91_adc_writel(st, AT91_ADC_IDR, 0xFFFFFFFF);
-        ret = request_irq(st->irq,
-                          at91_adc_interrupt,
-                          0,
-                          pdev->dev.driver->name,
-                          idev);
+
+        if (st->caps->has_tsmr)
+                ret = request_irq(st->irq, at91_adc_9x5_interrupt, 0,
+                                  pdev->dev.driver->name, idev);
+        else
+                ret = request_irq(st->irq, at91_adc_rl_interrupt, 0,
+                                  pdev->dev.driver->name, idev);
         if (ret) {
                 dev_err(&pdev->dev, "Failed to allocate IRQ.\n");
                 return ret;
@@ -1070,12 +1182,6 @@ static int at91_adc_probe(struct platform_device *pdev)
                         goto error_disable_adc_clk;
                 }
         } else {
-                if (!st->caps->has_tsmr) {
-                        dev_err(&pdev->dev, "We don't support non-TSMR adc\n");
-                        ret = -ENODEV;
-                        goto error_disable_adc_clk;
-                }
-
                 ret = at91_ts_register(st, pdev);
                 if (ret)
                         goto error_disable_adc_clk;
diff --git a/include/linux/platform_data/at91_adc.h b/include/linux/platform_data/at91_adc.h
index fcf73879dbfe..7819fc787731 100644
--- a/include/linux/platform_data/at91_adc.h
+++ b/include/linux/platform_data/at91_adc.h
@@ -7,6 +7,12 @@
 #ifndef _AT91_ADC_H_
 #define _AT91_ADC_H_
 
+enum atmel_adc_ts_type {
+        ATMEL_ADC_TOUCHSCREEN_NONE = 0,
+        ATMEL_ADC_TOUCHSCREEN_4WIRE = 4,
+        ATMEL_ADC_TOUCHSCREEN_5WIRE = 5,
+};
+
 /**
  * struct at91_adc_trigger - description of triggers
  * @name:               name of the trigger advertised to the user
@@ -28,6 +34,7 @@ struct at91_adc_trigger {
  * @trigger_number:             Number of triggers available in the ADC
  * @use_external_triggers:      does the board has external triggers availables
  * @vref:                       Reference voltage for the ADC in millivolts
+ * @touchscreen_type:           If a touchscreen is connected, its type (4 or 5 wires)
  */
 struct at91_adc_data {
         unsigned long                   channels_used;
@@ -36,6 +43,7 @@ struct at91_adc_data {
         u8                              trigger_number;
         bool                            use_external_triggers;
         u16                             vref;
+        enum atmel_adc_ts_type          touchscreen_type;
 };
 
 extern void __init at91_add_device_adc(struct at91_adc_data *data);