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rtc: rv3029: Add functions for EEPROM access 

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

Signed-off-by: Michael Buesch <m@bues.ch>
Signed-off-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>
hifive-unleashed-5.1
Michael Büsch 2016-03-04 22:40:55 +01:00 committed by Alexandre Belloni
parent 2dca3d9e14
commit a7f6e28741
1 changed files with 125 additions and 0 deletions
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125
drivers/rtc/rtc-rv3029c2.c
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@ -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)
{