Commit 9ea7c790 authored by Alexandre Belloni's avatar Alexandre Belloni Committed by Jonathan Cameron
Browse files

iio:common:ms_sensors:ms_sensors_i2c: add support for alternative PROM layout 



Currently, only the 112bit PROM with 7 words is supported. However the ms58xx
family also have devices with a 128bit PROM on 8 words. See AN520:
C-CODE EXAMPLE FOR MS56XX, MS57XX (EXCEPT ANALOG SENSOR), AND MS58XX SERIES
PRESSURE SENSORS and the various device datasheets.

The difference is that the CRC is the 4 LSBs of word7 instead of being the
4 MSBs of word0.

Signed-off-by: default avatarAlexandre Belloni <alexandre.belloni@bootlin.com>
Link: https://lore.kernel.org/r/20210109231148.1168104-6-alexandre.belloni@bootlin.com


Signed-off-by: default avatarJonathan Cameron <Jonathan.Cameron@huawei.com>
parent 7ae7f750

drivers/iio/common/ms_sensors/ms_sensors_i2c.c

+59 −11
Original line number Diff line number Diff line
@@ -488,21 +488,18 @@ int ms_sensors_ht_read_humidity(struct ms_ht_dev *dev_data, 
EXPORT_SYMBOL(ms_sensors_ht_read_humidity);



/**

 * ms_sensors_tp_crc_valid() - CRC check function for

 * ms_sensors_tp_crc4() - Calculate PROM CRC for

 *     Temperature and pressure devices.

 *     This function is only used when reading PROM coefficients

 *

 * @prom:	pointer to PROM coefficients array

 *

 * Return: True if CRC is ok.

 * Return: CRC.

 */

static bool ms_sensors_tp_crc_valid(u16 *prom)

static u8 ms_sensors_tp_crc4(u16 *prom)

{

	unsigned int cnt, n_bit;

	u16 n_rem = 0x0000, crc_read = prom[0], crc = (*prom & 0xF000) >> 12;



	prom[MS_SENSORS_TP_PROM_WORDS_NB - 1] = 0;

	prom[0] &= 0x0FFF;      /* Clear the CRC computation part */

	u16 n_rem = 0x0000;



	for (cnt = 0; cnt < MS_SENSORS_TP_PROM_WORDS_NB * 2; cnt++) {

		if (cnt % 2 == 1)
@@ -517,10 +514,55 @@ static bool ms_sensors_tp_crc_valid(u16 *prom) 
				n_rem <<= 1;

		}

	}

	n_rem >>= 12;

	prom[0] = crc_read;



	return n_rem == crc;

	return n_rem >> 12;

}



/**

 * ms_sensors_tp_crc_valid_112() - CRC check function for

 *     Temperature and pressure devices for 112bit PROM.

 *     This function is only used when reading PROM coefficients

 *

 * @prom:	pointer to PROM coefficients array

 *

 * Return: True if CRC is ok.

 */

static bool ms_sensors_tp_crc_valid_112(u16 *prom)

{

	u16 w0 = prom[0], crc_read = (w0 & 0xF000) >> 12;

	u8 crc;



	prom[0] &= 0x0FFF;      /* Clear the CRC computation part */

	prom[MS_SENSORS_TP_PROM_WORDS_NB - 1] = 0;



	crc = ms_sensors_tp_crc4(prom);



	prom[0] = w0;



	return crc == crc_read;

}



/**

 * ms_sensors_tp_crc_valid_128() - CRC check function for

 *     Temperature and pressure devices for 128bit PROM.

 *     This function is only used when reading PROM coefficients

 *

 * @prom:	pointer to PROM coefficients array

 *

 * Return: True if CRC is ok.

 */

static bool ms_sensors_tp_crc_valid_128(u16 *prom)

{

	u16 w7 = prom[7], crc_read = w7 & 0x000F;

	u8 crc;



	prom[7] &= 0xFF00;      /* Clear the CRC and LSB part */



	crc = ms_sensors_tp_crc4(prom);



	prom[7] = w7;



	return crc == crc_read;

}



/**
@@ -535,6 +577,7 @@ static bool ms_sensors_tp_crc_valid(u16 *prom) 
int ms_sensors_tp_read_prom(struct ms_tp_dev *dev_data)

{

	int i, ret;

	bool valid;



	for (i = 0; i < dev_data->hw->prom_len; i++) {

		ret = ms_sensors_read_prom_word(
@@ -546,7 +589,12 @@ int ms_sensors_tp_read_prom(struct ms_tp_dev *dev_data) 
			return ret;

	}



	if (!ms_sensors_tp_crc_valid(dev_data->prom)) {

	if (dev_data->hw->prom_len == 8)

		valid = ms_sensors_tp_crc_valid_128(dev_data->prom);

	else

		valid = ms_sensors_tp_crc_valid_112(dev_data->prom);



	if (!valid) {

		dev_err(&dev_data->client->dev,

			"Calibration coefficients crc check error\n");

		return -ENODEV;