Commit 7ae7f750 authored by Alexandre Belloni's avatar Alexandre Belloni Committed by Jonathan Cameron
Browse files

iio:common:ms_sensors:ms_sensors_i2c: rework CRC calculation helper 



The CRC calculation always happens on 8 words which is why there is an
extra element in the prom array of struct ms_tp_dev. However, on ms5637 and
similar, only 7 words are readable.

Then, set MS_SENSORS_TP_PROM_WORDS_NB to 8 and stop passing a len parameter
to ms_sensors_tp_crc_valid as this simply hide the fact that it is
hardcoded.

Finally, use the newly introduced hw->prom_len to know how many words can be
read.

Signed-off-by: default avatarAlexandre Belloni <alexandre.belloni@bootlin.com>
Link: https://lore.kernel.org/r/20210109231148.1168104-5-alexandre.belloni@bootlin.com


Signed-off-by: default avatarJonathan Cameron <Jonathan.Cameron@huawei.com>
parent 07498719

drivers/iio/common/ms_sensors/ms_sensors_i2c.c

+5 −7
Original line number Diff line number Diff line
@@ -493,19 +493,18 @@ EXPORT_SYMBOL(ms_sensors_ht_read_humidity); 
 *     This function is only used when reading PROM coefficients

 *

 * @prom:	pointer to PROM coefficients array

 * @len:	length of PROM coefficients array

 *

 * Return: True if CRC is ok.

 */

static bool ms_sensors_tp_crc_valid(u16 *prom, u8 len)

static bool ms_sensors_tp_crc_valid(u16 *prom)

{

	unsigned int cnt, n_bit;

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



	prom[len - 1] = 0;

	prom[MS_SENSORS_TP_PROM_WORDS_NB - 1] = 0;

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



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

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

		if (cnt % 2 == 1)

			n_rem ^= prom[cnt >> 1] & 0x00FF;

		else
@@ -537,7 +536,7 @@ int ms_sensors_tp_read_prom(struct ms_tp_dev *dev_data) 
{

	int i, ret;



	for (i = 0; i < MS_SENSORS_TP_PROM_WORDS_NB; i++) {

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

		ret = ms_sensors_read_prom_word(

			dev_data->client,

			MS_SENSORS_TP_PROM_READ + (i << 1),
@@ -547,8 +546,7 @@ int ms_sensors_tp_read_prom(struct ms_tp_dev *dev_data) 
			return ret;

	}



	if (!ms_sensors_tp_crc_valid(dev_data->prom,

				     MS_SENSORS_TP_PROM_WORDS_NB + 1)) {

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

		dev_err(&dev_data->client->dev,

			"Calibration coefficients crc check error\n");

		return -ENODEV;

drivers/iio/common/ms_sensors/ms_sensors_i2c.h

+2 −2
Original line number Diff line number Diff line
@@ -11,7 +11,7 @@ 
#include <linux/i2c.h>

#include <linux/mutex.h>



#define MS_SENSORS_TP_PROM_WORDS_NB		7

#define MS_SENSORS_TP_PROM_WORDS_NB		8



/**

 * struct ms_ht_dev - Humidity/Temperature sensor device structure
@@ -47,7 +47,7 @@ struct ms_tp_dev { 
	struct i2c_client *client;

	struct mutex lock;

	const struct ms_tp_hw_data *hw;

	u16 prom[MS_SENSORS_TP_PROM_WORDS_NB + 1];

	u16 prom[MS_SENSORS_TP_PROM_WORDS_NB];

	u8 res_index;

};