Subject: [PATCH] add omap34xx temperature monitoring support

From: [email-masked] (Pavel Machek)
Date: Fri, 26 Dec 2014 11:29:34 +0100

Signed-off-by: Pavel Machek <[email-masked]>

diff --git a/drivers/hwmon/Kconfig b/drivers/hwmon/Kconfig
index 6529c09..9007ca9 100644
--- a/drivers/hwmon/Kconfig
+++ b/drivers/hwmon/Kconfig
@@ -28,6 +28,10 @@ config HWMON_VID
 	tristate
 	default n
 
+config SENSORS_OMAP34XX
+	bool "TI OMAP34xx internal temperature sensor"
+	depends on ARCH_OMAP3 && HIGH_RES_TIMERS
+
 config HWMON_DEBUG_CHIP
 	bool "Hardware Monitoring Chip debugging messages"
 	default n
diff --git a/drivers/hwmon/Makefile b/drivers/hwmon/Makefile
index 6728064..5c3b5d1 100644
--- a/drivers/hwmon/Makefile
+++ b/drivers/hwmon/Makefile
@@ -120,6 +120,7 @@ obj-$(CONFIG_SENSORS_NCT6683)	+= nct6683.o
 obj-$(CONFIG_SENSORS_NCT6775)	+= nct6775.o
 obj-$(CONFIG_SENSORS_NCT7802)	+= nct7802.o
 obj-$(CONFIG_SENSORS_NTC_THERMISTOR)	+= ntc_thermistor.o
+obj-$(CONFIG_SENSORS_OMAP34XX)  += omap34xx_temp.o
 obj-$(CONFIG_SENSORS_PC87360)	+= pc87360.o
 obj-$(CONFIG_SENSORS_PC87427)	+= pc87427.o
 obj-$(CONFIG_SENSORS_PCF8591)	+= pcf8591.o
diff --git a/drivers/hwmon/omap34xx_temp.c b/drivers/hwmon/omap34xx_temp.c
new file mode 100644
index 0000000..bc7a72f
--- /dev/null
+++ b/drivers/hwmon/omap34xx_temp.c
@@ -0,0 +1,263 @@
+/*
+ * omap34xx_temp.c - Linux kernel module for OMAP34xx hardware monitoring
+ *
+ * Copyright (C) 2008 Nokia Corporation
+ *
+ * Written by Peter De Schrijver <[email-masked]>
+ *
+ * Inspired by k8temp.c
+ *
+ * This file is subject to the terms and conditions of the GNU General
+ * Public License. See the file "COPYING" in the main directory of this
+ * archive for more details.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+#include <linux/clk.h>
+#include <linux/hrtimer.h>
+#include <linux/module.h>
+#include <linux/hwmon.h>
+#include <linux/hwmon-sysfs.h>
+#include <linux/err.h>
+#include <linux/platform_device.h>
+#include <linux/io.h>
+#include <linux/slab.h>
+
+#include "../../arch/arm/mach-omap2/control.h"
+
+#define TEMP_SENSOR_SOC BIT(8)
+#define TEMP_SENSOR_EOCZ BIT(7)
+
+/* minimum delay for EOCZ rise after SOC rise is
+ * 11 cycles of the 32.768Khz clock */
+#define EOCZ_MIN_RISING_DELAY (11 * 30518)
+
+/* maximum delay for EOCZ rise after SOC rise is
+ * 14 cycles of the 32.768Khz clock */
+#define EOCZ_MAX_RISING_DELAY (14 * 30518)
+
+/* minimum delay for EOCZ falling is
+ * 36 cycles of the 32.768Khz clock */
+#define EOCZ_MIN_FALLING_DELAY (36 * 30518)
+
+/* maximum delay for EOCZ falling is
+ * 40 cycles of the 32.768Khz clock */
+#define EOCZ_MAX_FALLING_DELAY (40 * 30518)
+
+struct omap34xx_data {
+	struct device *hwmon_dev;
+	struct clk *clk_32k;
+	struct mutex update_lock;
+	const char *name;
+	char valid;
+	unsigned long last_updated;
+	u32 temp;
+};
+
+static struct platform_device omap34xx_temp_device = {
+	.name	= "omap34xx_temp",
+	.id	= -1,
+};
+
+static int adc_to_temp[] = {
+	-40, -40, -40, -40, -40, -39, -38, -36, -34, -32, -31, -29, -28, -26,
+	-25, -24, -22, -21, -19, -18, -17, -15, -14, -12, -11, -9, -8, -7, -5,
+	-4, -2, -1, 0, 1, 3, 4, 5, 7, 8, 10, 11, 13, 14, 15, 17, 18, 20, 21,
+	22, 24, 25, 27, 28, 30, 31, 32, 34, 35, 37, 38, 39, 41, 42, 44, 45,
+	47, 48, 49, 51, 52, 53, 55, 56, 58, 59, 60, 62, 63, 65, 66, 67, 69,
+	70, 72, 73, 74, 76, 77, 79, 80, 81, 83, 84, 85, 87, 88, 89, 91, 92,
+	94, 95, 96, 98, 99, 100, 102, 103, 105, 106, 107, 109, 110, 111, 113,
+	114, 116, 117, 118, 120, 121, 122, 124, 124, 125, 125, 125, 125, 125};
+
+static inline u32 wait_for_eocz(int min_delay, int max_delay, u32 level)
+{
+	struct timespec timeout;
+	ktime_t expire;
+	u32 temp_sensor_reg;
+
+	level &= 1;
+	level *= TEMP_SENSOR_EOCZ;
+
+	expire = ktime_add_ns(ktime_get(), max_delay);
+	timeout = ns_to_timespec(min_delay);
+	hrtimer_nanosleep(&timeout, NULL, HRTIMER_MODE_REL, CLOCK_MONOTONIC);
+	do {
+		temp_sensor_reg = omap_ctrl_readl(OMAP343X_CONTROL_TEMP_SENSOR);
+		if ((temp_sensor_reg & TEMP_SENSOR_EOCZ) == level)
+			break;
+	} while (ktime_us_delta(expire, ktime_get()) > 0);
+
+	return (temp_sensor_reg & TEMP_SENSOR_EOCZ) == level;
+}
+
+static void omap34xx_update(struct omap34xx_data *data)
+{
+	u32 temp_sensor_reg;
+
+	mutex_lock(&data->update_lock);
+
+	if (!data->valid
+	    || time_after(jiffies, data->last_updated + HZ)) {
+		clk_prepare_enable(data->clk_32k);
+
+		temp_sensor_reg = omap_ctrl_readl(OMAP343X_CONTROL_TEMP_SENSOR);
+		temp_sensor_reg |= TEMP_SENSOR_SOC;
+		omap_ctrl_writel(temp_sensor_reg, OMAP343X_CONTROL_TEMP_SENSOR);
+
+		if (!wait_for_eocz(EOCZ_MIN_RISING_DELAY,
+					EOCZ_MAX_RISING_DELAY, 1))
+			goto err;
+
+		temp_sensor_reg = omap_ctrl_readl(OMAP343X_CONTROL_TEMP_SENSOR);
+		temp_sensor_reg &= ~TEMP_SENSOR_SOC;
+		omap_ctrl_writel(temp_sensor_reg, OMAP343X_CONTROL_TEMP_SENSOR);
+
+		if (!wait_for_eocz(EOCZ_MIN_FALLING_DELAY,
+					EOCZ_MAX_FALLING_DELAY, 0))
+			goto err;
+
+		data->temp = omap_ctrl_readl(OMAP343X_CONTROL_TEMP_SENSOR) &
+						((1<<7) - 1);
+		data->last_updated = jiffies;
+		data->valid = 1;
+
+err:
+		clk_disable_unprepare(data->clk_32k);
+	}
+
+	mutex_unlock(&data->update_lock);
+}
+
+static ssize_t show_name(struct device *dev,
+			struct device_attribute *devattr, char *buf)
+{
+	struct omap34xx_data *data = dev_get_drvdata(dev);
+
+	return sprintf(buf, "%s\n", data->name);
+}
+
+static ssize_t show_temp_raw(struct device *dev,
+			 struct device_attribute *devattr, char *buf)
+{
+	struct omap34xx_data *data = dev_get_drvdata(dev);
+
+	omap34xx_update(data);
+
+	return sprintf(buf, "%d\n", data->temp);
+}
+
+static ssize_t show_temp(struct device *dev,
+			 struct device_attribute *devattr, char *buf)
+{
+	struct omap34xx_data *data = dev_get_drvdata(dev);
+
+	omap34xx_update(data);
+
+	return sprintf(buf, "%d\n", adc_to_temp[data->temp]);
+}
+
+static SENSOR_DEVICE_ATTR_2(temp1_input, S_IRUGO, show_temp, NULL, 0, 0);
+static SENSOR_DEVICE_ATTR_2(temp1_input_raw, S_IRUGO, show_temp_raw,
+				NULL, 0, 0);
+static DEVICE_ATTR(name, S_IRUGO, show_name, NULL);
+
+static int omap34xx_temp_probe(void)
+{
+	int err;
+	struct omap34xx_data *data;
+
+	err = platform_device_register(&omap34xx_temp_device);
+	if (err) {
+		pr_err("Unable to register omap34xx temperature device\n");
+		goto exit;
+	}
+
+	data = kzalloc(sizeof(struct omap34xx_data), GFP_KERNEL);
+	if (!data) {
+		err = -ENOMEM;
+		goto exit_platform;
+	}
+
+	dev_set_drvdata(&omap34xx_temp_device.dev, data);
+	mutex_init(&data->update_lock);
+	data->name = "omap34xx_temp";
+
+	data->clk_32k = clk_get(&omap34xx_temp_device.dev, "ts_fck");
+	if (IS_ERR(data->clk_32k)) {
+		err = PTR_ERR(data->clk_32k);
+		goto exit_free;
+	}
+
+	err = device_create_file(&omap34xx_temp_device.dev,
+				 &sensor_dev_attr_temp1_input.dev_attr);
+	if (err)
+		goto clock_free;
+
+	err = device_create_file(&omap34xx_temp_device.dev,
+				 &sensor_dev_attr_temp1_input_raw.dev_attr);
+	if (err)
+		goto exit_remove;
+
+	err = device_create_file(&omap34xx_temp_device.dev, &dev_attr_name);
+	if (err)
+		goto exit_remove_raw;
+
+	data->hwmon_dev = hwmon_device_register(&omap34xx_temp_device.dev);
+
+	if (IS_ERR(data->hwmon_dev)) {
+		err = PTR_ERR(data->hwmon_dev);
+		goto exit_remove_all;
+	}
+
+	return 0;
+
+exit_remove_all:
+	device_remove_file(&omap34xx_temp_device.dev,
+			   &dev_attr_name);
+exit_remove_raw:
+	device_remove_file(&omap34xx_temp_device.dev,
+			   &sensor_dev_attr_temp1_input_raw.dev_attr);
+exit_remove:
+	device_remove_file(&omap34xx_temp_device.dev,
+			   &sensor_dev_attr_temp1_input.dev_attr);
+clock_free:
+	clk_put(data->clk_32k);
+
+exit_free:
+	kfree(data);
+exit_platform:
+	platform_device_unregister(&omap34xx_temp_device);
+exit:
+	return err;
+}
+
+static int __init omap34xx_temp_init(void)
+{
+	return omap34xx_temp_probe();
+}
+
+static void __exit omap34xx_temp_exit(void)
+{
+	struct omap34xx_data *data =
+			dev_get_drvdata(&omap34xx_temp_device.dev);
+
+	clk_put(data->clk_32k);
+	hwmon_device_unregister(data->hwmon_dev);
+	device_remove_file(&omap34xx_temp_device.dev,
+			   &sensor_dev_attr_temp1_input.dev_attr);
+	device_remove_file(&omap34xx_temp_device.dev, &dev_attr_name);
+	kfree(data);
+	platform_device_unregister(&omap34xx_temp_device);
+}
+
+MODULE_AUTHOR("Peter De Schrijver");
+MODULE_DESCRIPTION("Omap34xx temperature sensor");
+MODULE_LICENSE("GPL");
+
+module_init(omap34xx_temp_init)
+module_exit(omap34xx_temp_exit)
+

-- 
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