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hwmon: (mr75203) modify the temperature equation according to series 5 datasheet

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Modify the equation and coefficients used to convert the digital output
to temperature according to series 5 of the Moortec Embedded Temperature
Sensor (METS) datasheet:
T = G + H * (n / cal5 - 0.5) + J * F

Where:
*) G = 60, H = 200, cal5 = 4094, J = -0.1.
*) F = frequency clock in MHz.
*) n is the digital output.

In code, the G, H and J coefficients are multiplied by a factor of 1000
to get the temperature in milli-Celsius.
Final result is clamped in case it exceeds min/max thresholds.

Change is done since it is unclear where the current equation and
coefficients came from.

Signed-off-by: Eliav Farber <farbere@amazon.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20220908152449.35457-16-farbere@amazon.com
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
This commit is contained in:
Eliav Farber 2022-09-08 15:24:43 +00:00 committed by Guenter Roeck
parent 430c0d7ff5
commit 94c025b6f7
1 changed files with 25 additions and 8 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

33
drivers/hwmon/mr75203.c
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@ -102,13 +102,19 @@
#define PVT_POLL_DELAY_US 20
#define PVT_POLL_TIMEOUT_US 20000
#define PVT_H_CONST 100000
#define PVT_CAL5_CONST 2047
#define PVT_G_CONST 40000
#define PVT_CONV_BITS 10
#define PVT_N_CONST 90
#define PVT_R_CONST 245805
#define PVT_TEMP_MIN_mC -40000
#define PVT_TEMP_MAX_mC 125000
/* Temperature coefficients for series 5 */
#define PVT_SERIES5_H_CONST 200000
#define PVT_SERIES5_G_CONST 60000
#define PVT_SERIES5_J_CONST -100
#define PVT_SERIES5_CAL5_CONST 4094
#define PRE_SCALER_X1 1
#define PRE_SCALER_X2 2
@ -174,13 +180,26 @@ static umode_t pvt_is_visible(const void *data, enum hwmon_sensor_types type,
return 0;
}
static long pvt_calc_temp(struct pvt_device *pvt, u32 nbs)
{
/*
* Convert the register value to degrees centigrade temperature:
* T = G + H * (n / cal5 - 0.5) + J * F
*/
s64 tmp = PVT_SERIES5_G_CONST +
PVT_SERIES5_H_CONST * (s64)nbs / PVT_SERIES5_CAL5_CONST -
PVT_SERIES5_H_CONST / 2 +
PVT_SERIES5_J_CONST * (s64)pvt->ip_freq / HZ_PER_MHZ;
return clamp_val(tmp, PVT_TEMP_MIN_mC, PVT_TEMP_MAX_mC);
}
static int pvt_read_temp(struct device *dev, u32 attr, int channel, long *val)
{
struct pvt_device *pvt = dev_get_drvdata(dev);
struct regmap *t_map = pvt->t_map;
u32 stat, nbs;
int ret;
u64 tmp;
switch (attr) {
case hwmon_temp_input:
@ -201,9 +220,7 @@ static int pvt_read_temp(struct device *dev, u32 attr, int channel, long *val)
* Convert the register value to
* degrees centigrade temperature
*/
tmp = nbs * PVT_H_CONST;
do_div(tmp, PVT_CAL5_CONST);
*val = tmp - PVT_G_CONST - pvt->ip_freq;
*val = pvt_calc_temp(pvt, nbs);
return 0;
default:
@ -327,7 +344,7 @@ static int pvt_init(struct pvt_device *pvt)
(key >> 1) << CLK_SYNTH_HI_SFT |
(key >> 1) << CLK_SYNTH_HOLD_SFT | CLK_SYNTH_EN;
pvt->ip_freq = sys_freq * 100 / (key + 2);
pvt->ip_freq = clk_get_rate(pvt->clk) / (key + 2);
if (t_num) {
ret = regmap_write(t_map, SDIF_SMPL_CTRL, 0x0);