[PATCH v3 1/8] drivers:input:tsc2007: add new common binding names, pre-calibration, flipping and rotation

H. Nikolaus Schaller
2016-09-23T12:41:09Z

commit b98abe52fa8e ("Input: add common DT binding for touchscreens")
introduced common DT bindings for touchscreens [1] and a helper function to
parse the DT.

commit ed7c9870c9bc ("Input: of_touchscreen - add support for inverted / swapped axes")
added another helper for parsing axis inversion and swapping
and applying them to x and y coordinates.

Both helpers have been integrated to accommodate any orientation of the
touch panel in relation to the LCD.

A new feature is to introduce scaling the min/max ADC values to the screen
size.

This makes it possible to pre-calibrate the touch so that is (almost)
exactly matches the LCD pixel coordinates it is glued onto. This allows to
well enough operate the touch before a user space calibration step can
improve the precision.

Finally, calculate_pressure has been renamed to calculate_resistance
because that is what it is doing.

[1]: Documentation/devicetree/bindings/input/touchscreen/touchscreen.txt

Signed-off-by: H. Nikolaus Schaller <hns@goldelico.com>
---
.../bindings/input/touchscreen/tsc2007.txt | 20 ++--
drivers/input/touchscreen/tsc2007.c | 126 +++++++++++++++++----
include/linux/i2c/tsc2007.h | 8 ++
3 files changed, 123 insertions(+), 31 deletions(-)

diff --git a/Documentation/devicetree/bindings/input/touchscreen/tsc2007.txt b/Documentation/devicetree/bindings/input/touchscreen/tsc2007.txt
index ec365e1..6e9fd55 100644
--- a/Documentation/devicetree/bindings/input/touchscreen/tsc2007.txt
+++ b/Documentation/devicetree/bindings/input/touchscreen/tsc2007.txt
@@ -6,6 +6,7 @@ Required properties:
- ti,x-plate-ohms: X-plate resistance in ohms.

Optional properties:
+- generic touch screen properties: see touchscreen binding [2].
- gpios: the interrupt gpio the chip is connected to (trough the penirq pin).
The penirq pin goes to low when the panel is touched.
(see GPIO binding[1] for more details).
@@ -13,17 +14,20 @@ Optional properties:
(see interrupt binding[0]).
- interrupts: (gpio) interrupt to which the chip is connected
(see interrupt binding[0]).
-- ti,max-rt: maximum pressure.
-- ti,fuzzx: specifies the absolute input fuzz x value.
- If set, it will permit noise in the data up to +- the value given to the fuzz
- parameter, that is used to filter noise from the event stream.
-- ti,fuzzy: specifies the absolute input fuzz y value.
-- ti,fuzzz: specifies the absolute input fuzz z value.
+- ti,max-rt: maximum pressure resistance above which samples are ignored
+ (default: 4095).
+- ti,report-resistance: report resistance (no pressure = max_rt) instead
+ of pressure (no pressure = 0).
+- ti,min-x: minimum value reported by X axis ADC (default 0).
+- ti,max-x: maximum value reported by X axis ADC (default 4095).
+- ti,min-y: minimum value reported by Y axis ADC (default 0).
+- ti,max-y: maximum value reported by Y axis ADC (default 4095).
- ti,poll-period: how much time to wait (in milliseconds) before reading again the
- values from the tsc2007.
+ values from the tsc2007 (default 1).

[0]: Documentation/devicetree/bindings/interrupt-controller/interrupts.txt
[1]: Documentation/devicetree/bindings/gpio/gpio.txt
+[2]: Documentation/devicetree/bindings/input/touchscreen/touchscreen.txt

Example:
&i2c1 {
@@ -35,6 +39,8 @@ Example:
interrupts = <0x0 0x8>;
gpios = <&gpio4 0 0>;
ti,x-plate-ohms = <180>;
+ touchscreen-size-x = <640>;
+ touchscreen-size-y = <480>;
};

/* ... */
diff --git a/drivers/input/touchscreen/tsc2007.c b/drivers/input/touchscreen/tsc2007.c
index 5d0cd51..9a11509 100644
--- a/drivers/input/touchscreen/tsc2007.c
+++ b/drivers/input/touchscreen/tsc2007.c
@@ -29,6 +29,7 @@
#include <linux/of_device.h>
#include <linux/of.h>
#include <linux/of_gpio.h>
+#include <linux/input/touchscreen.h>

#define TSC2007_MEASURE_TEMP0 (0x0 << 4)
#define TSC2007_MEASURE_AUX (0x2 << 4)
@@ -74,6 +75,14 @@ struct tsc2007 {

u16 model;
u16 x_plate_ohms;
+
+ struct touchscreen_properties prop;
+
+ bool report_resistance;
+ u16 min_x;
+ u16 min_y;
+ u16 max_x;
+ u16 max_y;
u16 max_rt;
unsigned long poll_period; /* in jiffies */
int fuzzx;
@@ -128,7 +137,8 @@ static void tsc2007_read_values(struct tsc2007 *tsc, struct ts_event *tc)
tsc2007_xfer(tsc, PWRDOWN);
}

-static u32 tsc2007_calculate_pressure(struct tsc2007 *tsc, struct ts_event *tc)
+static u32 tsc2007_calculate_resistance(struct tsc2007 *tsc,
+ struct ts_event *tc)
{
u32 rt = 0;

@@ -177,12 +187,13 @@ static irqreturn_t tsc2007_soft_irq(int irq, void *handle)
struct ts_event tc;
u32 rt;

+ dev_dbg(&ts->client->dev, "soft irq %d\n", irq);
while (!ts->stopped && tsc2007_is_pen_down(ts)) {

/* pen is down, continue with the measurement */
tsc2007_read_values(ts, &tc);

- rt = tsc2007_calculate_pressure(ts, &tc);
+ rt = tsc2007_calculate_resistance(ts, &tc);

if (!rt && !ts->get_pendown_state) {
/*
@@ -194,21 +205,45 @@ static irqreturn_t tsc2007_soft_irq(int irq, void *handle)
}

if (rt <= ts->max_rt) {
+ int sx, sy;
+
dev_dbg(&ts->client->dev,
"DOWN point(%4d,%4d), pressure (%4u)\n",
tc.x, tc.y, rt);

- input_report_key(input, BTN_TOUCH, 1);
- input_report_abs(input, ABS_X, tc.x);
- input_report_abs(input, ABS_Y, tc.y);
+ if (!ts->report_resistance)
+ rt = ts->max_rt - rt;
+
+ /* scale ADC values to desired output range */
+ sx = (ts->prop.max_x * (tc.x - ts->min_x))
+ / (ts->max_x - ts->min_x);
+ sy = (ts->prop.max_y * (tc.y - ts->min_y))
+ / (ts->max_y - ts->min_y);
+ rt = (input->absinfo[ABS_PRESSURE].maximum * rt) /
+ ts->max_rt;
+
+ dev_dbg(&ts->client->dev,
+ "Scaled point(%4d,%4d), pressure (%4u)\n",
+ sx, sy, rt);
+
+ /* report event */
+ if (!ts->pendown) {
+ input_report_key(input, BTN_TOUCH, 1);
+ ts->pendown = true;
+ }
+
+ touchscreen_report_pos(ts->input, &ts->prop,
+ (unsigned int) sx,
+ (unsigned int) sy,
+ false);
input_report_abs(input, ABS_PRESSURE, rt);

input_sync(input);

} else {
/*
- * Sample found inconsistent by debouncing or pressure is
- * beyond the maximum. Don't report it to user space,
+ * Sample found inconsistent by debouncing or resistance
+ * is beyond the maximum. Don't report it to user space,
* repeat at least once more the measurement.
*/
dev_dbg(&ts->client->dev, "ignored pressure %d\n", rt);
@@ -233,6 +268,7 @@ static irqreturn_t tsc2007_hard_irq(int irq, void *handle)
{
struct tsc2007 *ts = handle;

+ dev_dbg(&ts->client->dev, "hard irq %d\n", irq);
if (tsc2007_is_pen_down(ts))
return IRQ_WAKE_THREAD;

@@ -303,14 +339,24 @@ static int tsc2007_probe_dt(struct i2c_client *client, struct tsc2007 *ts)
else
ts->max_rt = MAX_12BIT;

- if (!of_property_read_u32(np, "ti,fuzzx", &val32))
- ts->fuzzx = val32;
+ ts->report_resistance =
+ of_property_read_bool(np, "ti,report-resistance");

- if (!of_property_read_u32(np, "ti,fuzzy", &val32))
- ts->fuzzy = val32;
+ touchscreen_parse_properties(ts->input, false, &ts->prop);

- if (!of_property_read_u32(np, "ti,fuzzz", &val32))
- ts->fuzzz = val32;
+ if (!of_property_read_u32(np, "ti,min-x", &val32))
+ ts->min_x = val32;
+ if (!of_property_read_u32(np, "ti,max-x", &val32))
+ ts->max_x = val32;
+ else
+ ts->max_x = MAX_12BIT;
+
+ if (!of_property_read_u32(np, "ti,min-y", &val32))
+ ts->min_y = val32;
+ if (!of_property_read_u32(np, "ti,max-y", &val32))
+ ts->max_y = val32;
+ else
+ ts->max_y = MAX_12BIT;

if (!of_property_read_u64(np, "ti,poll-period", &val64))
ts->poll_period = msecs_to_jiffies(val64);
@@ -332,6 +378,22 @@ static int tsc2007_probe_dt(struct i2c_client *client, struct tsc2007 *ts)
"GPIO not specified in DT (of_get_gpio returned %d)\n",
ts->gpio);

+ dev_dbg(&client->dev,
+ "min/max_x (%4d,%4d)\n",
+ ts->min_x, ts->max_x);
+ dev_dbg(&client->dev,
+ "min/max_y (%4d,%4d)\n",
+ ts->min_y, ts->max_y);
+ dev_dbg(&client->dev,
+ "max_rt (%4d)\n",
+ ts->max_rt);
+ dev_dbg(&client->dev,
+ "size (%4d,%4d)\n",
+ ts->prop.max_x, ts->prop.max_y);
+ dev_dbg(&client->dev,
+ "ts-gpio: %d\n",
+ ts->gpio);
+
return 0;
}
#else
@@ -349,6 +411,14 @@ static int tsc2007_probe_pdev(struct i2c_client *client, struct tsc2007 *ts,
ts->model = pdata->model;
ts->x_plate_ohms = pdata->x_plate_ohms;
ts->max_rt = pdata->max_rt ? : MAX_12BIT;
+ ts->prop.swap_x_y = pdata->swap_xy;
+ ts->prop.invert_x = pdata->invert_x;
+ ts->prop.invert_y = pdata->invert_y;
+ ts->report_resistance = pdata->report_resistance;
+ ts->min_x = pdata->min_x ? : 0;
+ ts->min_y = pdata->min_y ? : 0;
+ ts->max_x = pdata->max_x ? : MAX_12BIT;
+ ts->max_y = pdata->max_y ? : MAX_12BIT;
ts->poll_period = msecs_to_jiffies(pdata->poll_period ? : 1);
ts->get_pendown_state = pdata->get_pendown_state;
ts->clear_penirq = pdata->clear_penirq;
@@ -388,13 +458,6 @@ static int tsc2007_probe(struct i2c_client *client,
if (!ts)
return -ENOMEM;

- if (pdata)
- err = tsc2007_probe_pdev(client, ts, pdata, id);
- else
- err = tsc2007_probe_dt(client, ts);
- if (err)
- return err;
-
input_dev = devm_input_allocate_device(&client->dev);
if (!input_dev)
return -ENOMEM;
@@ -419,12 +482,25 @@ static int tsc2007_probe(struct i2c_client *client,
input_set_drvdata(input_dev, ts);

input_dev->evbit[0] = BIT_MASK(EV_KEY) | BIT_MASK(EV_ABS);
+ input_dev->absbit[0] = BIT_MASK(ABS_X) | BIT_MASK(ABS_Y) |
+ BIT_MASK(ABS_PRESSURE);
input_dev->keybit[BIT_WORD(BTN_TOUCH)] = BIT_MASK(BTN_TOUCH);

- input_set_abs_params(input_dev, ABS_X, 0, MAX_12BIT, ts->fuzzx, 0);
- input_set_abs_params(input_dev, ABS_Y, 0, MAX_12BIT, ts->fuzzy, 0);
- input_set_abs_params(input_dev, ABS_PRESSURE, 0, MAX_12BIT,
- ts->fuzzz, 0);
+ if (pdata) {
+ err = tsc2007_probe_pdev(client, ts, pdata, id);
+ if (err)
+ return err;
+ input_set_abs_params(input_dev, ABS_X, 0, ts->max_x-ts->min_x,
+ ts->fuzzx, 0);
+ input_set_abs_params(input_dev, ABS_Y, 0, ts->max_y-ts->min_y,
+ ts->fuzzy, 0);
+ input_set_abs_params(input_dev, ABS_PRESSURE, 0, ts->max_rt,
+ ts->fuzzz, 0);
+ } else {
+ err = tsc2007_probe_dt(client, ts);
+ if (err)
+ return err;
+ }

if (pdata) {
if (pdata->exit_platform_hw) {
@@ -443,6 +519,8 @@ static int tsc2007_probe(struct i2c_client *client,
pdata->init_platform_hw();
}

+ dev_dbg(&client->dev, "request irq %d\n",
+ ts->irq);
err = devm_request_threaded_irq(&client->dev, ts->irq,
tsc2007_hard_irq, tsc2007_soft_irq,
IRQF_ONESHOT,
diff --git a/include/linux/i2c/tsc2007.h b/include/linux/i2c/tsc2007.h
index 4f35b6a..632db20 100644
--- a/include/linux/i2c/tsc2007.h
+++ b/include/linux/i2c/tsc2007.h
@@ -6,6 +6,14 @@
struct tsc2007_platform_data {
u16 model; /* 2007. */
u16 x_plate_ohms; /* must be non-zero value */
+ bool swap_xy; /* swap x and y axis */
+ bool invert_x;
+ bool invert_y;
+ bool report_resistance;
+ u16 min_x; /* min and max values reported by ADC */
+ u16 min_y;
+ u16 max_x;
+ u16 max_y;
u16 max_rt; /* max. resistance above which samples are ignored */
unsigned long poll_period; /* time (in ms) between samples */
int fuzzx; /* fuzz factor for X, Y and pressure axes */
--
2.7.3