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 a58188ed4666fe9fb23f3666957229e30739e53b..e59b8a54d9a7d3ca9c936ad05f3301cc29fba10a 100644 (file)
--- 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)
 {