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>
diff --git a/drivers/rtc/rtc-rv3029c2.c b/drivers/rtc/rtc-rv3029c2.c
index a58188e..e59b8a5 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 @@
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)
{