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Commit a7f6e287 authored by Michael Buesch's avatar Michael Buesch Committed by Alexandre Belloni
Browse files

rtc: rv3029: Add functions for EEPROM access 



This adds functions for access to the EEPROM memory on the rv3029.

Signed-off-by: default avatarMichael Buesch <m@bues.ch>
Signed-off-by: default avatarAlexandre Belloni <alexandre.belloni@free-electrons.com>
parent 2dca3d9e

drivers/rtc/rtc-rv3029c2.c

+125 −0
Original line number Diff line number Diff line
@@ -19,6 +19,9 @@ 
#include <linux/i2c.h>

#include <linux/bcd.h>

#include <linux/rtc.h>

#include <linux/delay.h>

#include <linux/of.h>





/* Register map */

/* control section */
@@ -186,6 +189,128 @@ rv3029_i2c_set_sr(struct i2c_client *client, u8 val) 
	return 0;

}



static int rv3029_eeprom_busywait(struct i2c_client *client)

{

	int i, ret;

	u8 sr;



	for (i = 100; i > 0; i--) {

		ret = rv3029_i2c_get_sr(client, &sr);

		if (ret < 0)

			break;

		if (!(sr & RV3029_STATUS_EEBUSY))

			break;

		usleep_range(1000, 10000);

	}

	if (i <= 0) {

		dev_err(&client->dev, "EEPROM busy wait timeout.\n");

		return -ETIMEDOUT;

	}



	return ret;

}



static int rv3029_eeprom_exit(struct i2c_client *client)

{

	/* Re-enable eeprom refresh */

	return rv3029_i2c_update_bits(client, RV3029_ONOFF_CTRL,

				      RV3029_ONOFF_CTRL_EERE,

				      RV3029_ONOFF_CTRL_EERE);

}



static int rv3029_eeprom_enter(struct i2c_client *client)

{

	int ret;

	u8 sr;



	/* Check whether we are in the allowed voltage range. */

	ret = rv3029_i2c_get_sr(client, &sr);

	if (ret < 0)

		return ret;

	if (sr & (RV3029_STATUS_VLOW1 | RV3029_STATUS_VLOW2)) {

		/* We clear the bits and retry once just in case

		 * we had a brown out in early startup.

		 */

		sr &= ~RV3029_STATUS_VLOW1;

		sr &= ~RV3029_STATUS_VLOW2;

		ret = rv3029_i2c_set_sr(client, sr);

		if (ret < 0)

			return ret;

		usleep_range(1000, 10000);

		ret = rv3029_i2c_get_sr(client, &sr);

		if (ret < 0)

			return ret;

		if (sr & (RV3029_STATUS_VLOW1 | RV3029_STATUS_VLOW2)) {

			dev_err(&client->dev,

				"Supply voltage is too low to safely access the EEPROM.\n");

			return -ENODEV;

		}

	}



	/* Disable eeprom refresh. */

	ret = rv3029_i2c_update_bits(client, RV3029_ONOFF_CTRL,

				     RV3029_ONOFF_CTRL_EERE, 0);

	if (ret < 0)

		return ret;



	/* Wait for any previous eeprom accesses to finish. */

	ret = rv3029_eeprom_busywait(client);

	if (ret < 0)

		rv3029_eeprom_exit(client);



	return ret;

}



static int rv3029_eeprom_read(struct i2c_client *client, u8 reg,

			      u8 buf[], size_t len)

{

	int ret, err;



	err = rv3029_eeprom_enter(client);

	if (err < 0)

		return err;



	ret = rv3029_i2c_read_regs(client, reg, buf, len);



	err = rv3029_eeprom_exit(client);

	if (err < 0)

		return err;



	return ret;

}



static int rv3029_eeprom_write(struct i2c_client *client, u8 reg,

			       u8 const buf[], size_t len)

{

	int ret, err;

	size_t i;

	u8 tmp;



	err = rv3029_eeprom_enter(client);

	if (err < 0)

		return err;



	for (i = 0; i < len; i++, reg++) {

		ret = rv3029_i2c_read_regs(client, reg, &tmp, 1);

		if (ret < 0)

			break;

		if (tmp != buf[i]) {

			ret = rv3029_i2c_write_regs(client, reg, &buf[i], 1);

			if (ret < 0)

				break;

		}

		ret = rv3029_eeprom_busywait(client);

		if (ret < 0)

			break;

	}



	err = rv3029_eeprom_exit(client);

	if (err < 0)

		return err;



	return ret;

}



static int

rv3029_i2c_read_time(struct i2c_client *client, struct rtc_time *tm)

{