Merge branch 'next' of git://git.kernel.org/pub/scm/linux/kernel/git/rzhang/linux

Pull thermal management updates from Zhang Rui:

 - fix a race condition issue in power allocator governor (Yi Zeng).

 - add support for AP806 and CP110 in armada thermal driver, together
   with several improvements (Baruch Siach, Miquel Raynal)

 - add support for r8z7743 in rcar thermal driver (Biju Das)

 - convert thermal core to use new hwmon API to avoid warning (Fabio
   Estevam)

 - small fixes and cleanups in thermal core and x86_pkg_thermal,
   int3400_thermal, hisi_thermal, mtk_thermal and imx_thermal drivers
   (Pravin Shedge, Geert Uytterhoeven, Alexey Khoroshilov, Brian Bian,
   Matthias Brugger, Nicolin Chen, Uwe Kleine-König)

* 'next' of git://git.kernel.org/pub/scm/linux/kernel/git/rzhang/linux: (25 commits)
  thermal: thermal_hwmon: Convert to hwmon_device_register_with_info()
  thermal/x86 pkg temp: Remove debugfs_create_u32() casts
  thermal: int3400_thermal: fix error handling in int3400_thermal_probe()
  thermal/drivers/hisi: Remove bogus const from function return type
  thermal: armada: Give meaningful names to the thermal zones
  thermal: armada: Wait sensors validity before exiting the init callback
  thermal: armada: Change sensors trim default value
  thermal: armada: Update Kconfig and module description
  thermal: armada: Add support for Armada CP110
  thermal: armada: Add support for Armada AP806
  thermal: armada: Use real status register name
  thermal: armada: Clarify control registers accesses
  thermal: armada: Simplify the check of the validity bit
  thermal: armada: Use msleep for long delays
  dt-bindings: thermal: Describe Armada AP806 and CP110
  dt-bindings: thermal: rcar: Add device tree support for r8a7743
  thermal: mtk: Cleanup unused defines
  thermal: imx: update to new formula according to NXP AN5215
  thermal: imx: use consistent style to write temperatures
  thermal: imx: improve comments describing algorithm for temp calculation
  ...

1 files changed, 33 insertions, 41 deletions

diff --git a/drivers/thermal/imx_thermal.c b/drivers/thermal/imx_thermal.c
index e7d4ffc3de7f..a67781b7a0b2 100644
--- a/drivers/thermal/imx_thermal.c
+++ b/drivers/thermal/imx_thermal.c
@@ -70,10 +70,6 @@ enum imx_thermal_trip {
 #define IMX_POLLING_DELAY		2000 /* millisecond */
 #define IMX_PASSIVE_DELAY		1000
 
-#define FACTOR0				10000000
-#define FACTOR1				15976
-#define FACTOR2				4297157
-
 #define TEMPMON_IMX6Q			1
 #define TEMPMON_IMX6SX			2
 
@@ -347,78 +343,74 @@ static struct thermal_zone_device_ops imx_tz_ops = {
 	.set_trip_temp = imx_set_trip_temp,
 };
 
-static int imx_init_calib(struct platform_device *pdev, u32 val)
+static int imx_init_calib(struct platform_device *pdev, u32 ocotp_ana1)
 {
 	struct imx_thermal_data *data = platform_get_drvdata(pdev);
-	int t1, n1;
+	int n1;
 	u64 temp64;
 
-	if (val == 0 || val == ~0) {
+	if (ocotp_ana1 == 0 || ocotp_ana1 == ~0) {
 		dev_err(&pdev->dev, "invalid sensor calibration data\n");
 		return -EINVAL;
 	}
 
 	/*
-	 * Sensor data layout:
-	 *   [31:20] - sensor value @ 25C
-	 * Use universal formula now and only need sensor value @ 25C
-	 * slope = 0.4297157 - (0.0015976 * 25C fuse)
+	 * The sensor is calibrated at 25 °C (aka T1) and the value measured
+	 * (aka N1) at this temperature is provided in bits [31:20] in the
+	 * i.MX's OCOTP value ANA1.
+	 * To find the actual temperature T, the following formula has to be used
+	 * when reading value n from the sensor:
+	 *
+	 * T = T1 + (N - N1) / (0.4148468 - 0.0015423 * N1) °C + 3.580661 °C
+	 *   = [T1' - N1 / (0.4148468 - 0.0015423 * N1) °C] + N / (0.4148468 - 0.0015423 * N1) °C
+	 *   = [T1' + N1 / (0.0015423 * N1 - 0.4148468) °C] - N / (0.0015423 * N1 - 0.4148468) °C
+	 *   = c2 - c1 * N
+	 *
+	 * with
+	 *
+	 *  T1' = 28.580661 °C
+	 *   c1 = 1 / (0.0015423 * N1 - 0.4297157) °C
+	 *   c2 = T1' + N1 / (0.0015423 * N1 - 0.4148468) °C
+	 *      = T1' + N1 * c1
 	 */
-	n1 = val >> 20;
-	t1 = 25; /* t1 always 25C */
+	n1 = ocotp_ana1 >> 20;
 
-	/*
-	 * Derived from linear interpolation:
-	 * slope = 0.4297157 - (0.0015976 * 25C fuse)
-	 * slope = (FACTOR2 - FACTOR1 * n1) / FACTOR0
-	 * (Nmeas - n1) / (Tmeas - t1) = slope
-	 * We want to reduce this down to the minimum computation necessary
-	 * for each temperature read.  Also, we want Tmeas in millicelsius
-	 * and we don't want to lose precision from integer division. So...
-	 * Tmeas = (Nmeas - n1) / slope + t1
-	 * milli_Tmeas = 1000 * (Nmeas - n1) / slope + 1000 * t1
-	 * milli_Tmeas = -1000 * (n1 - Nmeas) / slope + 1000 * t1
-	 * Let constant c1 = (-1000 / slope)
-	 * milli_Tmeas = (n1 - Nmeas) * c1 + 1000 * t1
-	 * Let constant c2 = n1 *c1 + 1000 * t1
-	 * milli_Tmeas = c2 - Nmeas * c1
-	 */
-	temp64 = FACTOR0;
-	temp64 *= 1000;
-	do_div(temp64, FACTOR1 * n1 - FACTOR2);
+	temp64 = 10000000; /* use 10^7 as fixed point constant for values in formula */
+	temp64 *= 1000; /* to get result in °mC */
+	do_div(temp64, 15423 * n1 - 4148468);
 	data->c1 = temp64;
-	data->c2 = n1 * data->c1 + 1000 * t1;
+	data->c2 = n1 * data->c1 + 28581;
 
 	return 0;
 }
 
-static void imx_init_temp_grade(struct platform_device *pdev, u32 val)
+static void imx_init_temp_grade(struct platform_device *pdev, u32 ocotp_mem0)
 {
 	struct imx_thermal_data *data = platform_get_drvdata(pdev);
 
 	/* The maximum die temp is specified by the Temperature Grade */
-	switch ((val >> 6) & 0x3) {
-	case 0: /* Commercial (0 to 95C) */
+	switch ((ocotp_mem0 >> 6) & 0x3) {
+	case 0: /* Commercial (0 to 95 °C) */
 		data->temp_grade = "Commercial";
 		data->temp_max = 95000;
 		break;
-	case 1: /* Extended Commercial (-20 to 105C) */
+	case 1: /* Extended Commercial (-20 °C to 105 °C) */
 		data->temp_grade = "Extended Commercial";
 		data->temp_max = 105000;
 		break;
-	case 2: /* Industrial (-40 to 105C) */
+	case 2: /* Industrial (-40 °C to 105 °C) */
 		data->temp_grade = "Industrial";
 		data->temp_max = 105000;
 		break;
-	case 3: /* Automotive (-40 to 125C) */
+	case 3: /* Automotive (-40 °C to 125 °C) */
 		data->temp_grade = "Automotive";
 		data->temp_max = 125000;
 		break;
 	}
 
 	/*
-	 * Set the critical trip point at 5C under max
-	 * Set the passive trip point at 10C under max (can change via sysfs)
+	 * Set the critical trip point at 5 °C under max
+	 * Set the passive trip point at 10 °C under max (changeable via sysfs)
 	 */
 	data->temp_critical = data->temp_max - (1000 * 5);
 	data->temp_passive = data->temp_max - (1000 * 10);