[PATCH] i2c: Extend ds1337 initialization

Add code to handle case where board firmware does not start the
RTC.

Signed-off-by: Jean Delvare <khali@linux-fr.org>
CC: James Chapman <jchapman@katalix.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 31 insertions, 6 deletions

diff --git a/drivers/i2c/chips/ds1337.c b/drivers/i2c/chips/ds1337.c
index 02682fb794c8..18228957606c 100644
--- a/drivers/i2c/chips/ds1337.c
+++ b/drivers/i2c/chips/ds1337.c
@@ -337,13 +337,38 @@ exit:
 
 static void ds1337_init_client(struct i2c_client *client)
 {
-        s32 val;
+        u8 status, control;
 
-        /* Ensure that device is set in 24-hour mode */
-        val = i2c_smbus_read_byte_data(client, DS1337_REG_HOUR);
-        if ((val >= 0) && (val & (1 << 6)))
-                i2c_smbus_write_byte_data(client, DS1337_REG_HOUR,
-                                          val & 0x3f);
+        /* On some boards, the RTC isn't configured by boot firmware.
+         * Handle that case by starting/configuring the RTC now.
+         */
+        status = i2c_smbus_read_byte_data(client, DS1337_REG_STATUS);
+        control = i2c_smbus_read_byte_data(client, DS1337_REG_CONTROL);
+
+        if ((status & 0x80) || (control & 0x80)) {
+                /* RTC not running */
+                u8 buf[16];
+                struct i2c_msg msg[1];
+
+                dev_dbg(&client->dev, "%s: RTC not running!\n", __FUNCTION__);
+
+                /* Initialize all, including STATUS and CONTROL to zero */
+                memset(buf, 0, sizeof(buf));
+                msg[0].addr = client->addr;
+                msg[0].flags = 0;
+                msg[0].len = sizeof(buf);
+                msg[0].buf = &buf[0];
+
+                i2c_transfer(client->adapter, msg, 1);
+        } else {
+                /* Running: ensure that device is set in 24-hour mode */
+                s32 val;
+
+                val = i2c_smbus_read_byte_data(client, DS1337_REG_HOUR);
+                if ((val >= 0) && (val & (1 << 6)))
+                        i2c_smbus_write_byte_data(client, DS1337_REG_HOUR,
+                                                  val & 0x3f);
+        }
 }
 
 static int ds1337_detach_client(struct i2c_client *client)