diff options
Diffstat (limited to 'drivers')
| -rw-r--r-- | drivers/rtc/rtc-rv3029c2.c | 125 |
1 files changed, 125 insertions, 0 deletions
diff --git a/drivers/rtc/rtc-rv3029c2.c b/drivers/rtc/rtc-rv3029c2.c index a58188ed4666..e59b8a54d9a7 100644 --- a/drivers/rtc/rtc-rv3029c2.c +++ b/drivers/rtc/rtc-rv3029c2.c @@ -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) { |