From 0130e6433130fb5b10c7821f476673d9c94a033b Mon Sep 17 00:00:00 2001 From: Peng Fan Date: Wed, 6 May 2015 14:47:02 +0800 Subject: MLK-10827 imx: mx6 update thermal driver according new equation MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit From IC guys: " After a thorough accuracy study of the Temp sense circuit, we found that with our current equation, an average part can read 7 degrees lower than a known forced temperature. We also found out that the standard variance was around 2C; which is the tightest distribution that we could create. We need to change the temp sense equation to center the average part around the target temperature. Old Equation: Temp = Troom,cal – slope*(Count measured – Count room fuse) Where Troom,cal = 25C and Slope = 0.4297157 – (0.0015974 * Count room fuse) New Equation: Temp = Troom,cal – slope*(Count measured – Count room fuse) +offset Where Troom,cal = 25C and Slope = 0.4445388 – (0.0016549 * Count room fuse) Offset = 3.580661 " According the new equation, update the thermal driver. c1 and c2 changed to u64 type and update comments. Conflicts: drivers/thermal/imx_thermal.c since to imx_v2014.04, there is no imx_thermal driver, implement the new equation in arch/arm/cpu/armv7/mx6/soc.c. Also drop the orignial way to calculate temp, but use the way in imx_v2015.04 which aligns with linux kernel Signed-off-by: Peng Fan (cherry picked from commit 87723f903454aaf17336e0fe9098ea7911c19f3c) (cherry picked from commit 7f8fa8b46f90d41fe3f37fbac40d8d773cdee5ce) --- arch/arm/cpu/armv7/mx6/soc.c | 59 +++++++++++++++++++++++++++----------------- 1 file changed, 36 insertions(+), 23 deletions(-) diff --git a/arch/arm/cpu/armv7/mx6/soc.c b/arch/arm/cpu/armv7/mx6/soc.c index 3cb5bdf..6af6b4c 100644 --- a/arch/arm/cpu/armv7/mx6/soc.c +++ b/arch/arm/cpu/armv7/mx6/soc.c @@ -17,6 +17,7 @@ #include #include #include +#include #include #include #include @@ -48,13 +49,12 @@ struct scu_regs { #define TEMPERATURE_MIN -40 #define TEMPERATURE_HOT 80 #define TEMPERATURE_MAX 125 -#define FACTOR1 15976 -#define FACTOR2 4297157 +#define FACTOR0 10000000 +#define FACTOR1 16549 +#define FACTOR2 4445388 +#define OFFSET 3580661 #define MEASURE_FREQ 327 -#define REG_VALUE_TO_CEL(ratio, raw) \ - ((raw_n40c - raw) * 100 / ratio - 40) - static unsigned int fuse = ~0; u32 get_cpu_rev(void) @@ -243,8 +243,9 @@ static void imx_set_wdog_powerdown(bool enable) static int read_cpu_temperature(int *temperature) { unsigned int ccm_ccgr2; - unsigned int reg, tmp; - unsigned int raw_25c, raw_n40c, ratio; + unsigned int reg, n_meas; + int t1, n1; + u64 temp64, c1, c2; struct mxc_ccm_reg *mxc_ccm = (struct mxc_ccm_reg *)CCM_BASE_ADDR; struct ocotp_regs *ocotp = (struct ocotp_regs *)OCOTP_BASE_ADDR; struct fuse_bank *bank = &ocotp->bank[1]; @@ -287,20 +288,33 @@ static int read_cpu_temperature(int *temperature) * [19:8] sensor value of hot * [7:0] hot temperature value */ - raw_25c = fuse >> 20; + n1 = fuse >> 20; + t1 = 25; /* t1 always 25C */ /* - * The universal equation for thermal sensor - * is slope = 0.4297157 - (0.0015976 * 25C fuse), - * here we convert them to integer to make them - * easy for counting, FACTOR1 is 15976, - * FACTOR2 is 4297157. Our ratio = -100 * slope + * Derived from linear interpolation: + * slope = 0.4445388 - (0.0016549 * 25C fuse) + * slope = (FACTOR2 - FACTOR1 * n1) / FACTOR0 + * offset = 3.580661 + * offset = OFFSET / 1000000 + * (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 + offset + * milli_Tmeas = 1000000 * (Nmeas - n1) / slope + 1000000 * t1 + OFFSET + * milli_Tmeas = -1000000 * (n1 - Nmeas) / slope + 1000000 * t1 + OFFSET + * Let constant c1 = (-1000000 / slope) + * milli_Tmeas = (n1 - Nmeas) * c1 + 1000000 * t1 + OFFSET + * Let constant c2 = n1 *c1 + 1000000 * t1 + * milli_Tmeas = (c2 - Nmeas * c1) / 1000000 + OFFSET + * Tmeas = ((c2 - Nmeas * c1) + OFFSET) / 1000000 */ - ratio = ((FACTOR1 * raw_25c - FACTOR2) + 50000) / 100000; - - debug("Thermal sensor with ratio = %d\n", ratio); - - raw_n40c = raw_25c + (13 * ratio) / 20; + temp64 = FACTOR0; + temp64 *= 1000000; + do_div(temp64, FACTOR1 * n1 - FACTOR2); + c1 = temp64; + c2 = n1 * c1 + 1000000 * t1; /* * now we only use single measure, every time we read @@ -325,14 +339,13 @@ static int read_cpu_temperature(int *temperature) udelay(10000); reg = readl(&mxc_ccm->tempsense0); - tmp = (reg & BM_ANADIG_TEMPSENSE0_TEMP_VALUE) + n_meas = (reg & BM_ANADIG_TEMPSENSE0_TEMP_VALUE) >> BP_ANADIG_TEMPSENSE0_TEMP_VALUE; writel(BM_ANADIG_TEMPSENSE0_FINISHED, &mxc_ccm->tempsense0_clr); - if (tmp <= raw_n40c) - *temperature = REG_VALUE_TO_CEL(ratio, tmp); - else - *temperature = TEMPERATURE_MIN; + /* Tmeas = (c2 - Nmeas * c1 + OFFSET) / 1000000 */ + *temperature = lldiv(c2 - n_meas * c1 + OFFSET, 1000000); + /* power down anatop thermal sensor */ writel(BM_ANADIG_TEMPSENSE0_POWER_DOWN, &mxc_ccm->tempsense0_set); writel(BM_ANADIG_ANA_MISC0_REFTOP_SELBIASOFF, &mxc_ccm->ana_misc0_clr); -- cgit v1.1