RE: [PATCH 2/2] hwmon: da9052: add support for TSI channel

From: Steve Twiss <hidden>
Date: 2017-06-28 17:03:57
Also in: linux-devicetree, linux-hwmon, lkml

Hi Sebastian,

On 26 June 2017 15:49 Sebastian Reichel wrote:

quoted hunk ↗ jump to hunk

Subject: [PATCH 2/2] hwmon: da9052: add support for TSI channel

TSI channel has a 4 channel mux connected to it and is normally
used for touchscreen support. The hardware may alternatively
use it as general purpose adc.

Signed-off-by: Sebastian Reichel <redacted>
---
 .../devicetree/bindings/mfd/da9052-i2c.txt         |   8 +
 drivers/hwmon/da9052-hwmon.c                       | 229
++++++++++++++++++++-
 drivers/input/touchscreen/da9052_tsi.c             |   5 +
 include/linux/mfd/da9052/da9052.h                  |   6 +
 4 files changed, 244 insertions(+), 4 deletions(-)

diff --git a/Documentation/devicetree/bindings/mfd/da9052-i2c.txt

b/Documentation/devicetree/bindings/mfd/da9052-i2c.txt
index 9554292dc6cb..94f3bb1d9a0a 100644

--- a/Documentation/devicetree/bindings/mfd/da9052-i2c.txt
+++ b/Documentation/devicetree/bindings/mfd/da9052-i2c.txt

@@ -4,6 +4,14 @@ Required properties:
 - compatible : Should be "dlg,da9052", "dlg,da9053-aa",
 			 "dlg,da9053-ab", or "dlg,da9053-bb"

+Optional properties:
+- diag,tsi-as-adc : Boolean, if set the X+, X-, Y+, Y- touchscreen
+                    input lines are used as general purpose analogue
+					input.
+- diag,tsiref-microvolt: Voltage applied to the TSIREF pin, which is
+                         used as reference voltage when reading TSI
+						 pins as ADC. Defaults to 2500000.
+

"dlg" is the standard vendor prefix we are using for Dialog Semiconductor
bindings. You can find this definition in the kernel file:
./Documentation/devicetree/bindings/vendor-prefixes.txt

quoted hunk ↗ jump to hunk

 Sub-nodes:
 - regulators : Contain the regulator nodes. The DA9052/53 regulators are
   bound using their names as listed below:

diff --git a/drivers/hwmon/da9052-hwmon.c b/drivers/hwmon/da9052-

hwmon.c
index c9832bfacfe5..a0b9d5498ba4 100644

--- a/drivers/hwmon/da9052-hwmon.c
+++ b/drivers/hwmon/da9052-hwmon.c

@@ -20,13 +20,17 @@
 #include <linux/module.h>
 #include <linux/slab.h>
 #include <linux/platform_device.h>
+#include <linux/property.h>

 #include <linux/mfd/da9052/da9052.h>
 #include <linux/mfd/da9052/reg.h>

 struct da9052_hwmon {
-	struct da9052	*da9052;
-	struct mutex	hwmon_lock;
+	struct da9052		*da9052;
+	struct mutex		hwmon_lock;
+	bool			tsi_as_adc;
+	int			tsiref_mv;
+	struct completion	tsidone;
 };

 static const char * const input_names[] = {

@@ -37,6 +41,10 @@ static const char * const input_names[] = {
 	[DA9052_ADC_IN4]	=	"ADC IN4",
 	[DA9052_ADC_IN5]	=	"ADC IN5",
 	[DA9052_ADC_IN6]	=	"ADC IN6",
+	[DA9052_ADC_TSI_XP]	=	"ADC TS X+",
+	[DA9052_ADC_TSI_YP]	=	"ADC TS Y+",
+	[DA9052_ADC_TSI_XN]	=	"ADC TS X-",
+	[DA9052_ADC_TSI_YN]	=	"ADC TS Y-",
 	[DA9052_ADC_TJUNC]	=	"BATTERY JUNCTION TEMP",
 	[DA9052_ADC_VBBAT]	=	"BACK-UP BATTERY VOLTAGE",
 };

@@ -59,6 +67,11 @@ static inline int vbbat_reg_to_mv(int value)
 	return DIV_ROUND_CLOSEST(value * 5000, 1023);
 }

+static inline int input_tsireg_to_mv(struct da9052_hwmon *hwmon, int

value)
+{
+	return DIV_ROUND_CLOSEST(value * hwmon->tsiref_mv, 1023);
+}
+
 static inline int da9052_enable_vddout_channel(struct da9052 *da9052)
 {
 	return da9052_reg_update(da9052, DA9052_ADC_CONT_REG,

@@ -154,6 +167,103 @@ static ssize_t da9052_read_misc_channel(struct

device *dev,
 	return sprintf(buf, "%d\n", input_reg_to_mv(ret));
 }

+static int da9052_request_tsi_read(struct da9052_hwmon *hwmon, int
channel)
+{
+	u8 val = BIT(6); /* TSI_MAN */

There is an explicit #define for bit 6 from the TSI control register B, in the
file include/linux/mfd/da9052/reg.h #define DA9052_TSICONTB_TSIMAN 0X40

+
+	switch (channel) {
+	case DA9052_ADC_TSI_XP:
+		val |= (0 << 4); /* TSI_MUX */
+		break;
+	case DA9052_ADC_TSI_YP:
+		val |= (1 << 4); /* TSI_MUX */
+		break;
+	case DA9052_ADC_TSI_XN:
+		val |= (2 << 4); /* TSI_MUX */
+		break;
+	case DA9052_ADC_TSI_YN:
+		val |= (3 << 4); /* TSI_MUX */
+		break;
+	}

Same for these magic numbers.
Although I don't find any entries for these in the reg.h file.

The datasheet for DA9053, Revision 2.1, says
(http://www.dialog-semiconductor.com/products/da9053)

bits (5:4)  R/W TSI_MUX
Direct setting of MUX selecting which XY pin is routed to ADC_IN7 input.

00: X+ (results will be stored in TSI_XM)
01: Y+ (results will be stored in TSI_YM)
10: X- (results will be stored in TSI_XM)
11: Y- (results will be stored in TSI_YM)

May I suggest adding explicit entries to the reg.h file, somewhere near the 
TSI CONTROL REGISTER B BITS line. Something like this:

#define DA9052_TSICONTB_TSIMUX_XP_XM	0x00
#define DA9052_TSICONTB_TSIMUX_YP_YM	0x10
#define DA9052_TSICONTB_TSIMUX_XN_XM	0x20
#define DA9052_TSICONTB_TSIMUX_YN_YM	0x30

+
+	return da9052_reg_write(hwmon->da9052, DA9052_TSI_CONT_B_REG, val);
+}
+
+static int da9052_get_tsi_result(struct da9052_hwmon *hwmon, int
channel)
+{
+	int msb, lsb;
+
+	switch (channel) {
+	case DA9052_ADC_TSI_XP:
+	case DA9052_ADC_TSI_XN:
+		msb = da9052_reg_read(hwmon->da9052, DA9052_TSI_X_MSB_REG);
+		if (msb < 0)
+			return msb;
+
+		lsb = da9052_reg_read(hwmon->da9052, DA9052_TSI_LSB_REG);
+		if (lsb < 0)
+			return lsb;

It seems you will risk having non-synchronous data reads by separating the MSB
and LSB read operations in this case.

Reading the datasheet on this, the TSI_X_MSB register latches the TSI_Y_MSB and
TSI_LSB registers, which in turn should allow for a single read operation across
these registers instead of four separate reads. The switch could then be
completed on the calculation instead across the four register reads.

da9052_group_read()?

+
+		break;
+	case DA9052_ADC_TSI_YP:
+	case DA9052_ADC_TSI_YN:
+		msb = da9052_reg_read(hwmon->da9052, DA9052_TSI_Y_MSB_REG);
+		if (msb < 0)
+			return msb;
+
+		lsb = da9052_reg_read(hwmon->da9052, DA9052_TSI_LSB_REG);
+		if (lsb < 0)
+			return lsb;
+		lsb >>= 2;

The header file does contain some symbols to access the bits in the register
fields for these MSB X/Y and LSB registers.

/* TSI X CO-ORDINATE MSB RESULT REGISTER BITS */
#define DA9052_TSIXMSB_TSIXM	0XFF

/* TSI Y CO-ORDINATE MSB RESULT REGISTER BITS */
#define DA9052_TSIYMSB_TSIYM	0XFF

/* TSI CO-ORDINATE LSB RESULT REGISTER BITS */
#define DA9052_TSILSB_PENDOWN	0X40
#define DA9052_TSILSB_TSIZL		0X30
#define DA9052_TSILSB_TSIYL		0X0C
#define DA9052_TSILSB_TSIXL		0X03

+
+		break;
+	default:
+		return -ENXIO;

Is this a function argument error and should be, EINVAL?

+	}
+
+	return (msb << 2) | (lsb & 0x3);
+}

Although the reg.h register header file does not explicitly label MASK defines,
and there do not seem to be any SHIFT defines in the TSI X/Y CO-ORDINATE bits,
new entries can be added if necessary.

quoted hunk ↗ jump to hunk

+
+
+static ssize_t __da9052_read_tsi(struct device *dev, int channel)
+{
+	struct da9052_hwmon *hwmon = dev_get_drvdata(dev);
+	int ret;
+
+	reinit_completion(&hwmon->tsidone);
+
+	ret = da9052_request_tsi_read(hwmon, channel);
+	if (ret < 0)
+		return ret;
+
+	/* Wait for an conversion done interrupt */
+	if (!wait_for_completion_timeout(&hwmon->tsidone,
+					 msecs_to_jiffies(500))) {
+		dev_err(dev, "timeout waiting for TSI conversion interrupt\n");
+		return -ETIMEDOUT;
+	}
+
+	return da9052_get_tsi_result(hwmon, channel);
+}
+
+static ssize_t da9052_read_tsi(struct device *dev,
+			       struct device_attribute *devattr,
+			       char *buf)
+{
+	struct da9052_hwmon *hwmon = dev_get_drvdata(dev);
+	int channel = to_sensor_dev_attr(devattr)->index;
+	int ret;
+
+	mutex_lock(&hwmon->hwmon_lock);
+	ret = __da9052_read_tsi(dev, channel);
+	mutex_unlock(&hwmon->hwmon_lock);
+
+	if (ret < 0)
+		return ret;
+	else
+		return sprintf(buf, "%d\n", input_tsireg_to_mv(hwmon, ret));
+}
+
 static ssize_t da9052_read_tjunc(struct device *dev,
 				 struct device_attribute *devattr, char *buf)
 {

@@ -196,6 +306,28 @@ static ssize_t show_label(struct device *dev,
 		       input_names[to_sensor_dev_attr(devattr)->index]);
 }

+static umode_t da9052_channel_is_visible(struct kobject *kobj,
+					 struct attribute *a, int index)
+{
+	struct device *dev = container_of(kobj, struct device, kobj);
+	struct da9052_hwmon *hwmon = dev_get_drvdata(dev);
+
+	switch (index) {
+	case DA9052_ADC_TSI_XP:
+	case DA9052_ADC_TSI_YP:
+	case DA9052_ADC_TSI_XN:
+	case DA9052_ADC_TSI_YN:
+		break;
+	default:
+		return a->mode;
+	}
+
+	if (!hwmon->tsi_as_adc)
+		return 0;
+
+	return a->mode;
+}
+
 static SENSOR_DEVICE_ATTR(in0_input, S_IRUGO, da9052_read_vddout,

NULL,
 			  DA9052_ADC_VDDOUT);
 static SENSOR_DEVICE_ATTR(in0_label, S_IRUGO, show_label, NULL,

@@ -221,6 +353,23 @@ static SENSOR_DEVICE_ATTR(in9_input, S_IRUGO,

da9052_read_vbbat, NULL,
 static SENSOR_DEVICE_ATTR(in9_label, S_IRUGO, show_label, NULL,
 			  DA9052_ADC_VBBAT);

+static SENSOR_DEVICE_ATTR(in70_input, S_IRUGO, da9052_read_tsi, NULL,
+			  DA9052_ADC_TSI_XP);
+static SENSOR_DEVICE_ATTR(in70_label, S_IRUGO, show_label, NULL,
+			  DA9052_ADC_TSI_XP);
+static SENSOR_DEVICE_ATTR(in71_input, S_IRUGO, da9052_read_tsi, NULL,
+			  DA9052_ADC_TSI_XN);
+static SENSOR_DEVICE_ATTR(in71_label, S_IRUGO, show_label, NULL,
+			  DA9052_ADC_TSI_XN);
+static SENSOR_DEVICE_ATTR(in72_input, S_IRUGO, da9052_read_tsi, NULL,
+			  DA9052_ADC_TSI_YP);
+static SENSOR_DEVICE_ATTR(in72_label, S_IRUGO, show_label, NULL,
+			  DA9052_ADC_TSI_YP);
+static SENSOR_DEVICE_ATTR(in73_input, S_IRUGO, da9052_read_tsi, NULL,
+			  DA9052_ADC_TSI_YN);
+static SENSOR_DEVICE_ATTR(in73_label, S_IRUGO, show_label, NULL,
+			  DA9052_ADC_TSI_YN);
+
 static SENSOR_DEVICE_ATTR(curr1_input, S_IRUGO, da9052_read_ich,
NULL,
 			  DA9052_ADC_ICH);
 static SENSOR_DEVICE_ATTR(curr1_label, S_IRUGO, show_label, NULL,

@@ -246,6 +395,14 @@ static struct attribute *da9052_attrs[] = {
 	&sensor_dev_attr_in5_label.dev_attr.attr,
 	&sensor_dev_attr_in6_input.dev_attr.attr,
 	&sensor_dev_attr_in6_label.dev_attr.attr,
+	&sensor_dev_attr_in70_input.dev_attr.attr,
+	&sensor_dev_attr_in70_label.dev_attr.attr,
+	&sensor_dev_attr_in71_input.dev_attr.attr,
+	&sensor_dev_attr_in71_label.dev_attr.attr,
+	&sensor_dev_attr_in72_input.dev_attr.attr,
+	&sensor_dev_attr_in72_label.dev_attr.attr,
+	&sensor_dev_attr_in73_input.dev_attr.attr,
+	&sensor_dev_attr_in73_label.dev_attr.attr,
 	&sensor_dev_attr_in9_input.dev_attr.attr,
 	&sensor_dev_attr_in9_label.dev_attr.attr,
 	&sensor_dev_attr_curr1_input.dev_attr.attr,
@@ -257,29 +414,93 @@ static struct attribute *da9052_attrs[] = {
 	NULL
 };

-ATTRIBUTE_GROUPS(da9052);
+static const struct attribute_group da9052_group = {
+	.attrs = da9052_attrs,
+	.is_visible = da9052_channel_is_visible,
+};
+__ATTRIBUTE_GROUPS(da9052);
+
+static irqreturn_t da9052_tsi_datardy_irq(int irq, void *data)
+{
+	struct da9052_hwmon *hwmon = data;
+	complete(&hwmon->tsidone);
+	return IRQ_HANDLED;
+}

 static int da9052_hwmon_probe(struct platform_device *pdev)
 {
 	struct device *dev = &pdev->dev;
 	struct da9052_hwmon *hwmon;
 	struct device *hwmon_dev;
+	int err;

 	hwmon = devm_kzalloc(dev, sizeof(struct da9052_hwmon),

GFP_KERNEL);
 	if (!hwmon)
 		return -ENOMEM;

+	platform_set_drvdata(pdev, hwmon);
+
 	mutex_init(&hwmon->hwmon_lock);
 	hwmon->da9052 = dev_get_drvdata(pdev->dev.parent);

+	init_completion(&hwmon->tsidone);
+
+	hwmon->tsi_as_adc =
+		device_property_read_bool(pdev->dev.parent, "diag,tsi-as-adc");

Dialog device tree bindings should be "dlg" not "diag".

quoted hunk ↗ jump to hunk

+
+	/* get tsiref from DT, default to 2.5 Volt (typ. value in datasheet) */
+	hwmon->tsiref_mv = 2500000;
+	device_property_read_u32(pdev->dev.parent, "diag,tsiref-microvolt",
+				 &hwmon->tsiref_mv);
+
+	/* convert from microvolt (DT) to millivolt (hwmon) */
+	hwmon->tsiref_mv /= 1000;
+
+	/* TSIREF must be between 1.8 and 2.6 Volt according to datasheet */
+	if (hwmon->tsiref_mv < 1800 || hwmon->tsiref_mv > 2600) {
+		dev_err(hwmon->da9052->dev, "invalid TSIREF voltage: %d\n",
+			hwmon->tsiref_mv);
+		return -ENXIO;
+	}
+
+	if (hwmon->tsi_as_adc) {
+		/* disable touchscreen features */
+		da9052_reg_write(hwmon->da9052, DA9052_TSI_CONT_A_REG, 0x00);
+
+		err = da9052_request_irq(hwmon->da9052, DA9052_IRQ_TSIREADY,
+					 "tsiready-irq" da9052_tsi_datardy_irq,
+					 hwmon);
+		if (err) {
+			dev_err(hwmon->da9052->dev,
+				"Failed to register TSIRDY IRQ: %d\n", err);
+			return err;
+		}
+	}
+
 	hwmon_dev = devm_hwmon_device_register_with_groups(dev, "da9052",
 							   hwmon,
 							   da9052_groups);
-	return PTR_ERR_OR_ZERO(hwmon_dev);
+	err = PTR_ERR_OR_ZERO(hwmon_dev);
+	if (err) {
+		if (hwmon->tsi_as_adc)
+			da9052_free_irq(hwmon->da9052, DA9052_IRQ_TSIREADY, hwmon);
+		return err;
+	}
+
+	return 0;
+}
+
+static int da9052_hwmon_remove(struct platform_device *pdev)
+{
+	struct da9052_hwmon *hwmon = platform_get_drvdata(pdev);
+	if (hwmon->tsi_as_adc)
+		da9052_free_irq(hwmon->da9052, DA9052_IRQ_TSIREADY, hwmon);
+	return 0;
 }

 static struct platform_driver da9052_hwmon_driver = {
 	.probe = da9052_hwmon_probe,
+	.remove = da9052_hwmon_remove,
 	.driver = {
 		.name = "da9052-hwmon",
 	},

diff --git a/drivers/input/touchscreen/da9052_tsi.c

b/drivers/input/touchscreen/da9052_tsi.c
index 5a013bb7bcad..f0cb239546a9 100644

--- a/drivers/input/touchscreen/da9052_tsi.c
+++ b/drivers/input/touchscreen/da9052_tsi.c

@@ -16,6 +16,7 @@
 #include <linux/delay.h>
 #include <linux/platform_device.h>
 #include <linux/interrupt.h>
+#include <linux/property.h>

 #include <linux/mfd/da9052/reg.h>
 #include <linux/mfd/da9052/da9052.h>

@@ -238,6 +239,10 @@ static int da9052_ts_probe(struct platform_device

*pdev)
 	if (!da9052)
 		return -EINVAL;

+	/* check if pins are used as general purpose ADC input */
+	if (device_property_read_bool(pdev->dev.parent, "diag,tsi-as-adc"))
+		return -ENODEV;
+

Doesn't this presume the hwmon driver is being used?
If this "tsi-as-adc" exists in the DT binary blob and the hwmon driver is not
added, would this still disable the TS?

quoted hunk ↗ jump to hunk

 	tsi = kzalloc(sizeof(struct da9052_tsi), GFP_KERNEL);
 	input_dev = input_allocate_device();
 	if (!tsi || !input_dev) {

diff --git a/include/linux/mfd/da9052/da9052.h

b/include/linux/mfd/da9052/da9052.h
index ce9230af09c2..ae5b663836d0 100644

--- a/include/linux/mfd/da9052/da9052.h
+++ b/include/linux/mfd/da9052/da9052.h

@@ -45,6 +45,12 @@
 #define DA9052_ADC_TJUNC	8
 #define DA9052_ADC_VBBAT	9

+/* TSI channel has its own 4 channel mux */
+#define DA9052_ADC_TSI_XP	70
+#define DA9052_ADC_TSI_XN	71
+#define DA9052_ADC_TSI_YP	72
+#define DA9052_ADC_TSI_YN	73
+
 #define DA9052_IRQ_DCIN	0
 #define DA9052_IRQ_VBUS	1
 #define DA9052_IRQ_DCINREM	2
--

2.11.0

Regards,
Steve

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