Commit 94c025b6 authored by Eliav Farber's avatar Eliav Farber Committed by Guenter Roeck
Browse files

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



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: default avatarEliav Farber <farbere@amazon.com>
Reviewed-by: default avatarAndy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20220908152449.35457-16-farbere@amazon.com


Signed-off-by: default avatarGuenter Roeck <linux@roeck-us.net>
parent 430c0d7f

drivers/hwmon/mr75203.c

+25 −8
Original line number Diff line number Diff line
@@ -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);