hwmon: Add driver for EXYNOS4 TMU

This patch allows to read temperature
from TMU(Thermal Management Unit) of SAMSUNG EXYNOS4 series of SoC.
Signed-off-by: Donggeun Kim <dg77.kim@samsung.com>
Signed-off-by: MyungJoo Ham <myungjoo.ham@samsung.com>
Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
Signed-off-by: Guenter Roeck <guenter.roeck@ericsson.com>

Documentation/hwmon/exynos4_tmu

+Kernel driver exynos4_tmu
+=================
+
+Supported chips:
+* ARM SAMSUNG EXYNOS4 series of SoC
+  Prefix: 'exynos4-tmu'
+  Datasheet: Not publicly available
+
+Authors: Donggeun Kim <dg77.kim@samsung.com>
+
+Description
+-----------
+
+This driver allows to read temperature inside SAMSUNG EXYNOS4 series of SoC.
+
+The chip only exposes the measured 8-bit temperature code value
+through a register.
+Temperature can be taken from the temperature code.
+There are three equations converting from temperature to temperature code.
+
+The three equations are:
+  1. Two point trimming
+	Tc = (T - 25) * (TI2 - TI1) / (85 - 25) + TI1
+
+  2. One point trimming
+	Tc = T + TI1 - 25
+
+  3. No trimming
+	Tc = T + 50
+
+  Tc: Temperature code, T: Temperature,
+  TI1: Trimming info for 25 degree Celsius (stored at TRIMINFO register)
+       Temperature code measured at 25 degree Celsius which is unchanged
+  TI2: Trimming info for 85 degree Celsius (stored at TRIMINFO register)
+       Temperature code measured at 85 degree Celsius which is unchanged
+
+TMU(Thermal Management Unit) in EXYNOS4 generates interrupt
+when temperature exceeds pre-defined levels.
+The maximum number of configurable threshold is four.
+The threshold levels are defined as follows:
+  Level_0: current temperature > trigger_level_0 + threshold
+  Level_1: current temperature > trigger_level_1 + threshold
+  Level_2: current temperature > trigger_level_2 + threshold
+  Level_3: current temperature > trigger_level_3 + threshold
+
+  The threshold and each trigger_level are set
+  through the corresponding registers.
+
+When an interrupt occurs, this driver notify user space of
+one of four threshold levels for the interrupt
+through kobject_uevent_env and sysfs_notify functions.
+Although an interrupt condition for level_0 can be set,
+it is not notified to user space through sysfs_notify function.
+
+Sysfs Interface
+---------------
+name		name of the temperature sensor
+		RO
+
+temp1_input	temperature
+		RO
+
+temp1_max	temperature for level_1 interrupt
+		RO
+
+temp1_crit	temperature for level_2 interrupt
+		RO
+
+temp1_emergency	temperature for level_3 interrupt
+		RO
+
+temp1_max_alarm	alarm for level_1 interrupt
+		RO
+
+temp1_crit_alarm
+		alarm for level_2 interrupt
+		RO
+
+temp1_emergency_alarm
+		alarm for level_3 interrupt
+		RO

drivers/hwmon/Kconfig

@@ -303,6 +303,16 @@ config SENSORS_DS1621
 	  This driver can also be built as a module.  If so, the module
 	  will be called ds1621.
 
+config SENSORS_EXYNOS4_TMU
+	tristate "Temperature sensor on Samsung EXYNOS4"
+	depends on EXYNOS4_DEV_TMU
+	help
+	  If you say yes here you get support for TMU (Thermal Managment
+	  Unit) on SAMSUNG EXYNOS4 series of SoC.
+
+	  This driver can also be built as a module. If so, the module
+	  will be called exynos4-tmu.
+
 config SENSORS_I5K_AMB
 	tristate "FB-DIMM AMB temperature sensor on Intel 5000 series chipsets"
 	depends on PCI && EXPERIMENTAL

drivers/hwmon/Makefile

@@ -47,6 +47,7 @@ obj-$(CONFIG_SENSORS_DS1621)	+= ds1621.o
 obj-$(CONFIG_SENSORS_EMC1403)	+= emc1403.o
 obj-$(CONFIG_SENSORS_EMC2103)	+= emc2103.o
 obj-$(CONFIG_SENSORS_EMC6W201)	+= emc6w201.o
+obj-$(CONFIG_SENSORS_EXYNOS4_TMU)	+= exynos4_tmu.o
 obj-$(CONFIG_SENSORS_F71805F)	+= f71805f.o
 obj-$(CONFIG_SENSORS_F71882FG)	+= f71882fg.o
 obj-$(CONFIG_SENSORS_F75375S)	+= f75375s.o

include/linux/platform_data/exynos4_tmu.h

+/*
+ * exynos4_tmu.h - Samsung EXYNOS4 TMU (Thermal Management Unit)
+ *
+ *  Copyright (C) 2011 Samsung Electronics
+ *  Donggeun Kim <dg77.kim@samsung.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
+ * (at your option) any later version.
+ *
+ * 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.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+ */
+
+#ifndef _LINUX_EXYNOS4_TMU_H
+#define _LINUX_EXYNOS4_TMU_H
+
+enum calibration_type {
+	TYPE_ONE_POINT_TRIMMING,
+	TYPE_TWO_POINT_TRIMMING,
+	TYPE_NONE,
+};
+
+/**
+ * struct exynos4_tmu_platform_data
+ * @threshold: basic temperature for generating interrupt
+ *	       25 <= threshold <= 125 [unit: degree Celsius]
+ * @trigger_levels: array for each interrupt levels
+ *	[unit: degree Celsius]
+ *	0: temperature for trigger_level0 interrupt
+ *	   condition for trigger_level0 interrupt:
+ *		current temperature > threshold + trigger_levels[0]
+ *	1: temperature for trigger_level1 interrupt
+ *	   condition for trigger_level1 interrupt:
+ *		current temperature > threshold + trigger_levels[1]
+ *	2: temperature for trigger_level2 interrupt
+ *	   condition for trigger_level2 interrupt:
+ *		current temperature > threshold + trigger_levels[2]
+ *	3: temperature for trigger_level3 interrupt
+ *	   condition for trigger_level3 interrupt:
+ *		current temperature > threshold + trigger_levels[3]
+ * @trigger_level0_en:
+ *	1 = enable trigger_level0 interrupt,
+ *	0 = disable trigger_level0 interrupt
+ * @trigger_level1_en:
+ *	1 = enable trigger_level1 interrupt,
+ *	0 = disable trigger_level1 interrupt
+ * @trigger_level2_en:
+ *	1 = enable trigger_level2 interrupt,
+ *	0 = disable trigger_level2 interrupt
+ * @trigger_level3_en:
+ *	1 = enable trigger_level3 interrupt,
+ *	0 = disable trigger_level3 interrupt
+ * @gain: gain of amplifier in the positive-TC generator block
+ *	0 <= gain <= 15
+ * @reference_voltage: reference voltage of amplifier
+ *	in the positive-TC generator block
+ *	0 <= reference_voltage <= 31
+ * @cal_type: calibration type for temperature
+ *
+ * This structure is required for configuration of exynos4_tmu driver.
+ */
+struct exynos4_tmu_platform_data {
+	u8 threshold;
+	u8 trigger_levels[4];
+	bool trigger_level0_en;
+	bool trigger_level1_en;
+	bool trigger_level2_en;
+	bool trigger_level3_en;
+
+	u8 gain;
+	u8 reference_voltage;
+
+	enum calibration_type cal_type;
+};
+#endif /* _LINUX_EXYNOS4_TMU_H */