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author | Peng Fan <Peng.Fan@freescale.com> | 2015-05-06 14:39:46 +0800 |
---|---|---|
committer | Ye Li <ye.li@nxp.com> | 2017-03-14 21:27:09 +0800 |
commit | 52a95d753328ce4df03ca7acae3295ceab53c66b (patch) | |
tree | 32685aff5d04460e798aea880b912fda1fcfee34 /drivers | |
parent | 88c32ab51fdc54fe029f03b1da80f58d0f0f78a6 (diff) | |
download | u-boot-imx-52a95d753328ce4df03ca7acae3295ceab53c66b.zip u-boot-imx-52a95d753328ce4df03ca7acae3295ceab53c66b.tar.gz u-boot-imx-52a95d753328ce4df03ca7acae3295ceab53c66b.tar.bz2 |
MLK-10827 imx: mx6 update thermal driver according new equation
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.
Signed-off-by: Peng Fan <Peng.Fan@freescale.com>
(cherry picked from commit 87723f903454aaf17336e0fe9098ea7911c19f3c)
(cherry picked from commit 3392203fc3ae2f0701461143094cfbb112f7bc04)
Diffstat (limited to 'drivers')
-rw-r--r-- | drivers/thermal/imx_thermal.c | 38 |
1 files changed, 21 insertions, 17 deletions
diff --git a/drivers/thermal/imx_thermal.c b/drivers/thermal/imx_thermal.c index 0509094..741a3f7 100644 --- a/drivers/thermal/imx_thermal.c +++ b/drivers/thermal/imx_thermal.c @@ -1,5 +1,5 @@ /* - * (C) Copyright 2014 Freescale Semiconductor, Inc. + * (C) Copyright 2014-2016 Freescale Semiconductor, Inc. * Author: Nitin Garg <nitin.garg@freescale.com> * Ye Li <Ye.Li@freescale.com> * @@ -22,8 +22,9 @@ /* board will busyloop until this many degrees C below CPU max temperature */ #define TEMPERATURE_HOT_DELTA 5 /* CPU maxT - 5C */ #define FACTOR0 10000000 -#define FACTOR1 15976 -#define FACTOR2 4297157 +#define FACTOR1 16549 +#define FACTOR2 4445388 +#define OFFSET 3580661 #define MEASURE_FREQ 327 #define TEMPERATURE_MIN -40 #define TEMPERATURE_HOT 85 @@ -54,39 +55,42 @@ static int read_cpu_temperature(struct udevice *dev) struct thermal_data *priv = dev_get_priv(dev); u32 fuse = priv->fuse; int t1, n1; - u32 c1, c2; + u64 c1, c2; u64 temp64; /* * Sensor data layout: * [31:20] - sensor value @ 25C * We use universal formula now and only need sensor value @ 25C - * slope = 0.4297157 - (0.0015976 * 25C fuse) + * slope = 0.4445388 - (0.0016549 * 25C fuse) */ n1 = fuse >> 20; t1 = 25; /* t1 always 25C */ /* * Derived from linear interpolation: - * slope = 0.4297157 - (0.0015976 * 25C fuse) + * 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 - * 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 + * 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 */ temp64 = FACTOR0; - temp64 *= 1000; + temp64 *= 1000000; do_div(temp64, FACTOR1 * n1 - FACTOR2); c1 = temp64; - c2 = n1 * c1 + 1000 * t1; + c2 = n1 * c1 + 1000000 * t1; /* * now we only use single measure, every time we read @@ -118,8 +122,8 @@ static int read_cpu_temperature(struct udevice *dev) >> TEMPSENSE0_TEMP_CNT_SHIFT; writel(TEMPSENSE0_FINISHED, &anatop->tempsense0_clr); - /* milli_Tmeas = c2 - Nmeas * c1 */ - temperature = (long)(c2 - n_meas * c1)/1000; + /* Tmeas = (c2 - Nmeas * c1 + OFFSET) / 1000000 */ + temperature = lldiv(c2 - n_meas * c1 + OFFSET, 1000000); /* power down anatop thermal sensor */ writel(TEMPSENSE0_POWER_DOWN, &anatop->tempsense0_set); |