[Letux-kernel] [PATCH v8 3/8] drivers:input:tsc2007: add iio interface to read external ADC input and temperature

H. Nikolaus Schaller hns at goldelico.com
Tue Nov 22 15:02:30 CET 2016


The tsc2007 chip not only has a resistive touch screen controller but
also an external AUX adc imput which can be used for an ambient
light sensor, battery voltage monitoring or any general purpose.

Additionally it can measure the chip temperature.

This extension provides an iio interface for these adc channels.

Since it is not wasting much resources and is very straightforward,
we simply provide all other adc channels as optional iio interfaces
as weel. This can be used for debugging or special applications.

This patch also splits the tsc2007 driver in several source files:
tsc2007.h -- constants, structs and stubs
tsc2007_core.c -- functional parts of the original driver
tsc2007_iio.c -- the optional iio stuff

Makefile magic allows to conditionally link the iio stuff
if CONFIG_IIO=y or =m in a way that it works with
CONFIG_TOUCHSCREEN_TSC2007=m.

Signed-off-by: H. Nikolaus Schaller <hns at goldelico.com>
Reviewed-by: Jonathan Cameron <jic23 at kernel.org>
---
 drivers/input/touchscreen/Makefile                 |   7 +
 drivers/input/touchscreen/tsc2007.h                | 116 ++++++++++++++++
 .../touchscreen/{tsc2007.c => tsc2007_core.c}      |  95 +++----------
 drivers/input/touchscreen/tsc2007_iio.c            | 150 +++++++++++++++++++++
 4 files changed, 294 insertions(+), 74 deletions(-)
 create mode 100644 drivers/input/touchscreen/tsc2007.h
 rename drivers/input/touchscreen/{tsc2007.c => tsc2007_core.c} (86%)
 create mode 100644 drivers/input/touchscreen/tsc2007_iio.c

diff --git a/drivers/input/touchscreen/Makefile b/drivers/input/touchscreen/Makefile
index 81b8645..3be0d19 100644
--- a/drivers/input/touchscreen/Makefile
+++ b/drivers/input/touchscreen/Makefile
@@ -80,6 +80,13 @@ obj-$(CONFIG_TOUCHSCREEN_TSC_SERIO)	+= tsc40.o
 obj-$(CONFIG_TOUCHSCREEN_TSC200X_CORE)	+= tsc200x-core.o
 obj-$(CONFIG_TOUCHSCREEN_TSC2004)	+= tsc2004.o
 obj-$(CONFIG_TOUCHSCREEN_TSC2005)	+= tsc2005.o
+tsc2007-y				:= tsc2007_core.o
+ifeq ($(CONFIG_IIO),y)
+tsc2007-y				+= tsc2007_iio.o
+endif
+ifeq ($(CONFIG_IIO),m)
+tsc2007-y				+= tsc2007_iio.o
+endif
 obj-$(CONFIG_TOUCHSCREEN_TSC2007)	+= tsc2007.o
 obj-$(CONFIG_TOUCHSCREEN_UCB1400)	+= ucb1400_ts.o
 obj-$(CONFIG_TOUCHSCREEN_WACOM_W8001)	+= wacom_w8001.o
diff --git a/drivers/input/touchscreen/tsc2007.h b/drivers/input/touchscreen/tsc2007.h
new file mode 100644
index 0000000..c25932f
--- /dev/null
+++ b/drivers/input/touchscreen/tsc2007.h
@@ -0,0 +1,116 @@
+/*
+ * Copyright (c) 2008 MtekVision Co., Ltd.
+ *	Kwangwoo Lee <kwlee at mtekvision.com>
+ *
+ * Using code from:
+ *  - ads7846.c
+ *	Copyright (c) 2005 David Brownell
+ *	Copyright (c) 2006 Nokia Corporation
+ *  - corgi_ts.c
+ *	Copyright (C) 2004-2005 Richard Purdie
+ *  - omap_ts.[hc], ads7846.h, ts_osk.c
+ *	Copyright (C) 2002 MontaVista Software
+ *	Copyright (C) 2004 Texas Instruments
+ *	Copyright (C) 2005 Dirk Behme
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License version 2 as
+ *  published by the Free Software Foundation.
+ */
+
+#include <linux/input/touchscreen.h>
+
+#define TSC2007_MEASURE_TEMP0		(0x0 << 4)
+#define TSC2007_MEASURE_AUX		(0x2 << 4)
+#define TSC2007_MEASURE_TEMP1		(0x4 << 4)
+#define TSC2007_ACTIVATE_XN		(0x8 << 4)
+#define TSC2007_ACTIVATE_YN		(0x9 << 4)
+#define TSC2007_ACTIVATE_YP_XN		(0xa << 4)
+#define TSC2007_SETUP			(0xb << 4)
+#define TSC2007_MEASURE_X		(0xc << 4)
+#define TSC2007_MEASURE_Y		(0xd << 4)
+#define TSC2007_MEASURE_Z1		(0xe << 4)
+#define TSC2007_MEASURE_Z2		(0xf << 4)
+
+#define TSC2007_POWER_OFF_IRQ_EN	(0x0 << 2)
+#define TSC2007_ADC_ON_IRQ_DIS0		(0x1 << 2)
+#define TSC2007_ADC_OFF_IRQ_EN		(0x2 << 2)
+#define TSC2007_ADC_ON_IRQ_DIS1		(0x3 << 2)
+
+#define TSC2007_12BIT			(0x0 << 1)
+#define TSC2007_8BIT			(0x1 << 1)
+
+#define	MAX_12BIT			((1 << 12) - 1)
+
+#define ADC_ON_12BIT	(TSC2007_12BIT | TSC2007_ADC_ON_IRQ_DIS0)
+
+#define READ_Y		(ADC_ON_12BIT | TSC2007_MEASURE_Y)
+#define READ_Z1		(ADC_ON_12BIT | TSC2007_MEASURE_Z1)
+#define READ_Z2		(ADC_ON_12BIT | TSC2007_MEASURE_Z2)
+#define READ_X		(ADC_ON_12BIT | TSC2007_MEASURE_X)
+#define PWRDOWN		(TSC2007_12BIT | TSC2007_POWER_OFF_IRQ_EN)
+
+struct ts_event {
+	u16	x;
+	u16	y;
+	u16	z1, z2;
+};
+
+struct tsc2007 {
+	struct input_dev	*input;
+	char			phys[32];
+
+	struct i2c_client	*client;
+
+	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;
+	int			fuzzy;
+	int			fuzzz;
+
+	unsigned int		gpio;
+	int			irq;
+
+	wait_queue_head_t	wait;
+	bool			stopped;
+	bool			pendown;
+
+	int			(*get_pendown_state)(struct device *);
+	void			(*clear_penirq)(void);
+
+	struct mutex		mlock;
+	struct iio_dev		*iio_dev;	/* optional */
+};
+
+int tsc2007_xfer(struct tsc2007 *tsc, u8 cmd);
+u32 tsc2007_calculate_resistance(struct tsc2007 *tsc,
+					struct ts_event *tc);
+bool tsc2007_is_pen_down(struct tsc2007 *ts);
+
+#if IS_ENABLED(CONFIG_IIO)
+
+/* defined in tsc2007_iio.c */
+int tsc2007_iio_configure(struct tsc2007 *ts);
+void tsc2007_iio_unconfigure(struct tsc2007 *ts);
+
+#else /* CONFIG_IIO */
+
+static inline int tsc2007_iio_configure(struct tsc2007 *ts)
+{
+	return 0;
+}
+static inline void tsc2007_iio_unconfigure(struct tsc2007 *ts)
+{
+}
+
+#endif /* CONFIG_IIO */
diff --git a/drivers/input/touchscreen/tsc2007.c b/drivers/input/touchscreen/tsc2007_core.c
similarity index 86%
rename from drivers/input/touchscreen/tsc2007.c
rename to drivers/input/touchscreen/tsc2007_core.c
index 76b462b..812ded8 100644
--- a/drivers/input/touchscreen/tsc2007.c
+++ b/drivers/input/touchscreen/tsc2007_core.c
@@ -27,79 +27,11 @@
 #include <linux/i2c.h>
 #include <linux/i2c/tsc2007.h>
 #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)
-#define TSC2007_MEASURE_TEMP1		(0x4 << 4)
-#define TSC2007_ACTIVATE_XN		(0x8 << 4)
-#define TSC2007_ACTIVATE_YN		(0x9 << 4)
-#define TSC2007_ACTIVATE_YP_XN		(0xa << 4)
-#define TSC2007_SETUP			(0xb << 4)
-#define TSC2007_MEASURE_X		(0xc << 4)
-#define TSC2007_MEASURE_Y		(0xd << 4)
-#define TSC2007_MEASURE_Z1		(0xe << 4)
-#define TSC2007_MEASURE_Z2		(0xf << 4)
-
-#define TSC2007_POWER_OFF_IRQ_EN	(0x0 << 2)
-#define TSC2007_ADC_ON_IRQ_DIS0		(0x1 << 2)
-#define TSC2007_ADC_OFF_IRQ_EN		(0x2 << 2)
-#define TSC2007_ADC_ON_IRQ_DIS1		(0x3 << 2)
-
-#define TSC2007_12BIT			(0x0 << 1)
-#define TSC2007_8BIT			(0x1 << 1)
-
-#define	MAX_12BIT			((1 << 12) - 1)
-
-#define ADC_ON_12BIT	(TSC2007_12BIT | TSC2007_ADC_ON_IRQ_DIS0)
-
-#define READ_Y		(ADC_ON_12BIT | TSC2007_MEASURE_Y)
-#define READ_Z1		(ADC_ON_12BIT | TSC2007_MEASURE_Z1)
-#define READ_Z2		(ADC_ON_12BIT | TSC2007_MEASURE_Z2)
-#define READ_X		(ADC_ON_12BIT | TSC2007_MEASURE_X)
-#define PWRDOWN		(TSC2007_12BIT | TSC2007_POWER_OFF_IRQ_EN)
-
-struct ts_event {
-	u16	x;
-	u16	y;
-	u16	z1, z2;
-};
-
-struct tsc2007 {
-	struct input_dev	*input;
-	char			phys[32];
-
-	struct i2c_client	*client;
-
-	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;
-	int			fuzzy;
-	int			fuzzz;
-
-	unsigned		gpio;
-	int			irq;
-
-	wait_queue_head_t	wait;
-	bool			stopped;
+#include "tsc2007.h"
 
-	int			(*get_pendown_state)(struct device *);
-	void			(*clear_penirq)(void);
-};
 
-static inline int tsc2007_xfer(struct tsc2007 *tsc, u8 cmd)
+int tsc2007_xfer(struct tsc2007 *tsc, u8 cmd)
 {
 	s32 data;
 	u16 val;
@@ -137,7 +69,7 @@ static void tsc2007_read_values(struct tsc2007 *tsc, struct ts_event *tc)
 	tsc2007_xfer(tsc, PWRDOWN);
 }
 
-static u32 tsc2007_calculate_resistance(struct tsc2007 *tsc,
+u32 tsc2007_calculate_resistance(struct tsc2007 *tsc,
 					struct ts_event *tc)
 {
 	u32 rt = 0;
@@ -158,7 +90,7 @@ static u32 tsc2007_calculate_resistance(struct tsc2007 *tsc,
 	return rt;
 }
 
-static bool tsc2007_is_pen_down(struct tsc2007 *ts)
+bool tsc2007_is_pen_down(struct tsc2007 *ts)
 {
 	/*
 	 * NOTE: We can't rely on the pressure to determine the pen down
@@ -191,7 +123,10 @@ static irqreturn_t tsc2007_soft_irq(int irq, void *handle)
 	while (!ts->stopped && tsc2007_is_pen_down(ts)) {
 
 		/* pen is down, continue with the measurement */
+
+		mutex_lock(&ts->mlock);
 		tsc2007_read_values(ts, &tc);
+		mutex_unlock(&ts->mlock);
 
 		rt = tsc2007_calculate_resistance(ts, &tc);
 
@@ -441,7 +376,8 @@ static void tsc2007_call_exit_platform_hw(void *data)
 static int tsc2007_probe(struct i2c_client *client,
 			 const struct i2c_device_id *id)
 {
-	const struct tsc2007_platform_data *pdata = dev_get_platdata(&client->dev);
+	const struct tsc2007_platform_data *pdata =
+		dev_get_platdata(&client->dev);
 	struct tsc2007 *ts;
 	struct input_dev *input_dev;
 	int err;
@@ -463,7 +399,9 @@ static int tsc2007_probe(struct i2c_client *client,
 	ts->client = client;
 	ts->irq = client->irq;
 	ts->input = input_dev;
+
 	init_waitqueue_head(&ts->wait);
+	mutex_init(&ts->mlock);
 
 	snprintf(ts->phys, sizeof(ts->phys),
 		 "%s/input0", dev_name(&client->dev));
@@ -534,7 +472,7 @@ static int tsc2007_probe(struct i2c_client *client,
 	if (err < 0) {
 		dev_err(&client->dev,
 			"Failed to setup chip: %d\n", err);
-		return err;	/* usually, chip does not respond */
+		return err;	/* chip does not respond */
 	}
 
 	err = input_register_device(input_dev);
@@ -544,6 +482,14 @@ static int tsc2007_probe(struct i2c_client *client,
 		return err;
 	}
 
+	return tsc2007_iio_configure(ts);
+}
+
+static int tsc2007_remove(struct i2c_client *client)
+{
+	struct tsc2007 *ts = i2c_get_clientdata(client);
+
+	tsc2007_iio_unconfigure(ts);
 	return 0;
 }
 
@@ -569,6 +515,7 @@ static struct i2c_driver tsc2007_driver = {
 	},
 	.id_table	= tsc2007_idtable,
 	.probe		= tsc2007_probe,
+	.remove		= tsc2007_remove,
 };
 
 module_i2c_driver(tsc2007_driver);
diff --git a/drivers/input/touchscreen/tsc2007_iio.c b/drivers/input/touchscreen/tsc2007_iio.c
new file mode 100644
index 0000000..ed79944
--- /dev/null
+++ b/drivers/input/touchscreen/tsc2007_iio.c
@@ -0,0 +1,150 @@
+/*
+ * Copyright (c) 2016 Golden Delicious Comp. GmbH&Co. KG
+ *	Nikolaus Schaller <hns at goldelico.com>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License version 2 as
+ *  published by the Free Software Foundation.
+ */
+
+#include <linux/i2c.h>
+#include <linux/iio/iio.h>
+#include "tsc2007.h"
+
+struct tsc2007_iio {
+	struct tsc2007 *ts;
+};
+
+#define TSC2007_CHAN_IIO(_chan, _name, _type, _chan_info) \
+{ \
+	.datasheet_name = _name, \
+	.type = _type, \
+	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |	\
+			BIT(_chan_info), \
+	.indexed = 1, \
+	.channel = _chan, \
+}
+
+static const struct iio_chan_spec tsc2007_iio_channel[] = {
+	TSC2007_CHAN_IIO(0, "x", IIO_VOLTAGE, IIO_CHAN_INFO_RAW),
+	TSC2007_CHAN_IIO(1, "y", IIO_VOLTAGE, IIO_CHAN_INFO_RAW),
+	TSC2007_CHAN_IIO(2, "z1", IIO_VOLTAGE, IIO_CHAN_INFO_RAW),
+	TSC2007_CHAN_IIO(3, "z2", IIO_VOLTAGE, IIO_CHAN_INFO_RAW),
+	TSC2007_CHAN_IIO(4, "adc", IIO_VOLTAGE, IIO_CHAN_INFO_RAW),
+	TSC2007_CHAN_IIO(5, "rt", IIO_VOLTAGE, IIO_CHAN_INFO_RAW), /* Ohms? */
+	TSC2007_CHAN_IIO(6, "pen", IIO_PRESSURE, IIO_CHAN_INFO_RAW),
+	TSC2007_CHAN_IIO(7, "temp0", IIO_TEMP, IIO_CHAN_INFO_RAW),
+	TSC2007_CHAN_IIO(8, "temp1", IIO_TEMP, IIO_CHAN_INFO_RAW),
+};
+
+static int tsc2007_read_raw(struct iio_dev *indio_dev,
+	struct iio_chan_spec const *chan, int *val, int *val2, long mask)
+{
+	struct tsc2007_iio *iio = iio_priv(indio_dev);
+	struct tsc2007 *tsc = iio->ts;
+	int adc_chan = chan->channel;
+	int ret = 0;
+
+	if (adc_chan >= ARRAY_SIZE(tsc2007_iio_channel))
+		return -EINVAL;
+
+	if (mask != IIO_CHAN_INFO_RAW)
+		return -EINVAL;
+
+	mutex_lock(&tsc->mlock);
+
+	switch (chan->channel) {
+	case 0:
+		*val = tsc2007_xfer(tsc, READ_X);
+		break;
+	case 1:
+		*val = tsc2007_xfer(tsc, READ_Y);
+		break;
+	case 2:
+		*val = tsc2007_xfer(tsc, READ_Z1);
+		break;
+	case 3:
+		*val = tsc2007_xfer(tsc, READ_Z2);
+		break;
+	case 4:
+		*val = tsc2007_xfer(tsc, (ADC_ON_12BIT | TSC2007_MEASURE_AUX));
+		break;
+	case 5: {
+		struct ts_event tc;
+
+		tc.x = tsc2007_xfer(tsc, READ_X);
+		tc.z1 = tsc2007_xfer(tsc, READ_Z1);
+		tc.z2 = tsc2007_xfer(tsc, READ_Z2);
+		*val = tsc2007_calculate_resistance(tsc, &tc);
+		break;
+	}
+	case 6:
+		*val = tsc2007_is_pen_down(tsc);
+		break;
+	case 7:
+		*val = tsc2007_xfer(tsc,
+				    (ADC_ON_12BIT | TSC2007_MEASURE_TEMP0));
+		break;
+	case 8:
+		*val = tsc2007_xfer(tsc,
+				    (ADC_ON_12BIT | TSC2007_MEASURE_TEMP1));
+		break;
+	}
+
+	/* Prepare for next touch reading - power down ADC, enable PENIRQ */
+	tsc2007_xfer(tsc, PWRDOWN);
+
+	mutex_unlock(&tsc->mlock);
+
+	ret = IIO_VAL_INT;
+
+	return ret;
+}
+
+static const struct iio_info tsc2007_iio_info = {
+	.read_raw = tsc2007_read_raw,
+	.driver_module = THIS_MODULE,
+};
+
+int tsc2007_iio_configure(struct tsc2007 *ts)
+{
+	int err;
+	struct iio_dev *indio_dev;
+	struct tsc2007_iio *iio;
+
+	indio_dev = devm_iio_device_alloc(&ts->client->dev,
+		sizeof(struct tsc2007_iio));
+	if (!indio_dev) {
+		dev_err(&ts->client->dev, "iio_device_alloc failed\n");
+		return -ENOMEM;
+	}
+
+	iio = iio_priv(indio_dev);
+	iio->ts = ts;
+	ts->iio_dev = (void *) indio_dev;
+
+	indio_dev->name = "tsc2007";
+	indio_dev->dev.parent = &ts->client->dev;
+	indio_dev->info = &tsc2007_iio_info;
+	indio_dev->modes = INDIO_DIRECT_MODE;
+	indio_dev->channels = tsc2007_iio_channel;
+	indio_dev->num_channels = ARRAY_SIZE(tsc2007_iio_channel);
+
+	err = iio_device_register(indio_dev);
+	if (err < 0) {
+		dev_err(&ts->client->dev, "iio_device_register() failed: %d\n",
+			err);
+		return err;
+	}
+
+	return 0;
+}
+EXPORT_SYMBOL(tsc2007_iio_configure);
+
+void tsc2007_iio_unconfigure(struct tsc2007 *ts)
+{
+	struct iio_dev *indio_dev = ts->iio_dev;
+
+	iio_device_unregister(indio_dev);
+}
+EXPORT_SYMBOL(tsc2007_iio_unconfigure);
-- 
2.7.3



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