Input: sun4i-ts - add support for temperature sensor

The sun4i resisitive touchscreen controller also comes with a built-in
temperature sensor. This commit adds support for it.

This commit also introduces a new "ts-attached" device-tree property,
when this is not set, the input part of the driver won't register. This way
the internal temperature sensor can be used to measure the SoC temperature
independent of there actually being a touchscreen attached to the controller.
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Acked-by: Maxime Ripard <maxime.ripard@free-electrons.com>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

Documentation/devicetree/bindings/input/touchscreen/sun4i.txt

@@ -6,10 +6,15 @@ Required properties:
  - reg: mmio address range of the chip
  - interrupts: interrupt to which the chip is connected
 
+Optional properties:
+ - allwinner,ts-attached: boolean indicating that an actual touchscreen is
+			  attached to the controller
+
 Example:
 
 	rtp: rtp@01c25000 {
 		compatible = "allwinner,sun4i-a10-ts";
 		reg = <0x01c25000 0x100>;
 		interrupts = <29>;
+		allwinner,ts-attached;
 	};

drivers/input/touchscreen/Kconfig

@@ -900,6 +900,7 @@ config TOUCHSCREEN_STMPE
 config TOUCHSCREEN_SUN4I
 	tristate "Allwinner sun4i resistive touchscreen controller support"
 	depends on ARCH_SUNXI || COMPILE_TEST
+	depends on HWMON
 	help
 	  This selects support for the resistive touchscreen controller
 	  found on Allwinner sunxi SoCs.

drivers/input/touchscreen/sun4i-ts.c

@@ -3,6 +3,9 @@
  *
  * Copyright (C) 2013 - 2014 Hans de Goede <hdegoede@redhat.com>
  *
+ * The hwmon parts are based on work by Corentin LABBE which is:
+ * Copyright (C) 2013 Corentin LABBE <clabbe.montjoie@gmail.com>
+ *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
  * the Free Software Foundation; either version 2 of the License, or
@@ -30,6 +33,7 @@
  */
 
 #include <linux/err.h>
+#include <linux/hwmon.h>
 #include <linux/init.h>
 #include <linux/input.h>
 #include <linux/interrupt.h>
@@ -106,14 +110,12 @@ struct sun4i_ts_data {
 	void __iomem *base;
 	unsigned int irq;
 	bool ignore_fifo_data;
+	int temp_data;
 };
 
-static irqreturn_t sun4i_ts_irq(int irq, void *dev_id)
+static void sun4i_ts_irq_handle_input(struct sun4i_ts_data *ts, u32 reg_val)
 {
-	struct sun4i_ts_data *ts = dev_id;
-	u32 reg_val, x, y;
-
-	reg_val  = readl(ts->base + TP_INT_FIFOS);
+	u32 x, y;
 
 	if (reg_val & FIFO_DATA_PENDING) {
 		x = readl(ts->base + TP_DATA);
@@ -139,6 +141,20 @@ static irqreturn_t sun4i_ts_irq(int irq, void *dev_id)
 		input_report_key(ts->input, BTN_TOUCH, 0);
 		input_sync(ts->input);
 	}
+}
+
+static irqreturn_t sun4i_ts_irq(int irq, void *dev_id)
+{
+	struct sun4i_ts_data *ts = dev_id;
+	u32 reg_val;
+
+	reg_val  = readl(ts->base + TP_INT_FIFOS);
+
+	if (reg_val & TEMP_DATA_PENDING)
+		ts->temp_data = readl(ts->base + TEMP_DATA);
+
+	if (ts->input)
+		sun4i_ts_irq_handle_input(ts, reg_val);
 
 	writel(reg_val, ts->base + TP_INT_FIFOS);
 
@@ -149,9 +165,9 @@ static int sun4i_ts_open(struct input_dev *dev)
 {
 	struct sun4i_ts_data *ts = input_get_drvdata(dev);
 
-	/* Flush, set trig level to 1, enable data and up irqs */
-	writel(DATA_IRQ_EN(1) | FIFO_TRIG(1) | FIFO_FLUSH(1) | TP_UP_IRQ_EN(1),
-	       ts->base + TP_INT_FIFOC);
+	/* Flush, set trig level to 1, enable temp, data and up irqs */
+	writel(TEMP_IRQ_EN(1) | DATA_IRQ_EN(1) | FIFO_TRIG(1) | FIFO_FLUSH(1) |
+		TP_UP_IRQ_EN(1), ts->base + TP_INT_FIFOC);
 
 	return 0;
 }
@@ -160,15 +176,46 @@ static void sun4i_ts_close(struct input_dev *dev)
 {
 	struct sun4i_ts_data *ts = input_get_drvdata(dev);
 
-	/* Deactivate all IRQs */
-	writel(0, ts->base + TP_INT_FIFOC);
+	/* Deactivate all input IRQs */
+	writel(TEMP_IRQ_EN(1), ts->base + TP_INT_FIFOC);
 }
 
+static ssize_t show_temp(struct device *dev, struct device_attribute *devattr,
+			 char *buf)
+{
+	struct sun4i_ts_data *ts = dev_get_drvdata(dev);
+
+	/* No temp_data until the first irq */
+	if (ts->temp_data == -1)
+		return -EAGAIN;
+
+	return sprintf(buf, "%d\n", (ts->temp_data - 1447) * 100);
+}
+
+static ssize_t show_temp_label(struct device *dev,
+			      struct device_attribute *devattr, char *buf)
+{
+	return sprintf(buf, "SoC temperature\n");
+}
+
+static DEVICE_ATTR(temp1_input, S_IRUGO, show_temp, NULL);
+static DEVICE_ATTR(temp1_label, S_IRUGO, show_temp_label, NULL);
+
+static struct attribute *sun4i_ts_attrs[] = {
+	&dev_attr_temp1_input.attr,
+	&dev_attr_temp1_label.attr,
+	NULL
+};
+ATTRIBUTE_GROUPS(sun4i_ts);
+
 static int sun4i_ts_probe(struct platform_device *pdev)
 {
 	struct sun4i_ts_data *ts;
 	struct device *dev = &pdev->dev;
+	struct device_node *np = dev->of_node;
+	struct device *hwmon;
 	int error;
+	bool ts_attached;
 
 	ts = devm_kzalloc(dev, sizeof(struct sun4i_ts_data), GFP_KERNEL);
 	if (!ts)
@@ -176,7 +223,10 @@ static int sun4i_ts_probe(struct platform_device *pdev)
 
 	ts->dev = dev;
 	ts->ignore_fifo_data = true;
+	ts->temp_data = -1;
 
+	ts_attached = of_property_read_bool(np, "allwinner,ts-attached");
+	if (ts_attached) {
 		ts->input = devm_input_allocate_device(dev);
 		if (!ts->input)
 			return -ENOMEM;
@@ -194,6 +244,7 @@ static int sun4i_ts_probe(struct platform_device *pdev)
 		input_set_abs_params(ts->input, ABS_X, 0, 4095, 0, 0);
 		input_set_abs_params(ts->input, ABS_Y, 0, 4095, 0, 0);
 		input_set_drvdata(ts->input, ts);
+	}
 
 	ts->base = devm_ioremap_resource(dev,
 			      platform_get_resource(pdev, IORESOURCE_MEM, 0));
@@ -232,14 +283,39 @@ static int sun4i_ts_probe(struct platform_device *pdev)
 	writel(STYLUS_UP_DEBOUN(5) | STYLUS_UP_DEBOUN_EN(1) | TP_MODE_EN(1),
 	       ts->base + TP_CTRL1);
 
+	hwmon = devm_hwmon_device_register_with_groups(ts->dev, "sun4i_ts",
+						       ts, sun4i_ts_groups);
+	if (IS_ERR(hwmon))
+		return PTR_ERR(hwmon);
+
+	writel(TEMP_IRQ_EN(1), ts->base + TP_INT_FIFOC);
+
+	if (ts_attached) {
 		error = input_register_device(ts->input);
-	if (error)
+		if (error) {
+			writel(0, ts->base + TP_INT_FIFOC);
 			return error;
+		}
+	}
 
 	platform_set_drvdata(pdev, ts);
 	return 0;
 }
 
+static int sun4i_ts_remove(struct platform_device *pdev)
+{
+	struct sun4i_ts_data *ts = platform_get_drvdata(pdev);
+
+	/* Explicit unregister to avoid open/close changing the imask later */
+	if (ts->input)
+		input_unregister_device(ts->input);
+
+	/* Deactivate all IRQs */
+	writel(0, ts->base + TP_INT_FIFOC);
+
+	return 0;
+}
+
 static const struct of_device_id sun4i_ts_of_match[] = {
 	{ .compatible = "allwinner,sun4i-a10-ts", },
 	{ /* sentinel */ }
@@ -253,6 +329,7 @@ static struct platform_driver sun4i_ts_driver = {
 		.of_match_table = of_match_ptr(sun4i_ts_of_match),
 	},
 	.probe	= sun4i_ts_probe,
+	.remove	= sun4i_ts_remove,
 };
 
 module_platform_driver(sun4i_ts_driver);