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authorMylène Josserand <mylene.josserand@free-electrons.com>2016-03-29 08:56:05 +0200
committerAlexandre Belloni <alexandre.belloni@free-electrons.com>2016-05-20 12:33:51 +0200
commit05a7f27a889f1635b7b7d5b051b17cacb25267fa (patch)
tree4198df3102566ceec1e0d65052be1179aa610ba1
parent3726a21833c9c96255735bddb5dacc8eacbff3ef (diff)
rtc: m41t80: handle oscillator failure bit
Handle the Oscillator Failure (OF) bit on each read of date-time. If the OF is set, an error is returned (-EINVAL) instead of the date-time. The OF bit is cleared each time the date is set. Signed-off-by: Mylène Josserand <mylene.josserand@free-electrons.com> Signed-off-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>
-rw-r--r--drivers/rtc/rtc-m41t80.c25
1 files changed, 23 insertions, 2 deletions
diff --git a/drivers/rtc/rtc-m41t80.c b/drivers/rtc/rtc-m41t80.c
index 5706e99..d1bf93a 100644
--- a/drivers/rtc/rtc-m41t80.c
+++ b/drivers/rtc/rtc-m41t80.c
@@ -56,6 +56,7 @@
#define M41T80_ALMON_AFE BIT(7) /* AFE: AF Enable Bit */
#define M41T80_ALMON_SQWE BIT(6) /* SQWE: SQW Enable Bit */
#define M41T80_ALHOUR_HT BIT(6) /* HT: Halt Update Bit */
+#define M41T80_FLAGS_OF BIT(2) /* OF: Oscillator Failure Bit */
#define M41T80_FLAGS_AF BIT(6) /* AF: Alarm Flag Bit */
#define M41T80_FLAGS_BATT_LOW BIT(4) /* BL: Battery Low Bit */
#define M41T80_WATCHDOG_RB2 BIT(7) /* RB: Watchdog resolution */
@@ -134,7 +135,16 @@ static int m41t80_get_datetime(struct i2c_client *client,
struct rtc_time *tm)
{
unsigned char buf[8];
- int err;
+ int err, flags;
+
+ flags = i2c_smbus_read_byte_data(client, M41T80_REG_FLAGS);
+ if (flags < 0)
+ return flags;
+
+ if (flags & M41T80_FLAGS_OF) {
+ dev_err(&client->dev, "Oscillator failure, data is invalid.\n");
+ return -EINVAL;
+ }
err = i2c_smbus_read_i2c_block_data(client, M41T80_REG_SSEC,
sizeof(buf), buf);
@@ -159,7 +169,7 @@ static int m41t80_get_datetime(struct i2c_client *client,
static int m41t80_set_datetime(struct i2c_client *client, struct rtc_time *tm)
{
unsigned char buf[8];
- int err;
+ int err, flags;
if (tm->tm_year < 100 || tm->tm_year > 199)
return -EINVAL;
@@ -180,6 +190,17 @@ static int m41t80_set_datetime(struct i2c_client *client, struct rtc_time *tm)
return err;
}
+ /* Clear the OF bit of Flags Register */
+ flags = i2c_smbus_read_byte_data(client, M41T80_REG_FLAGS);
+ if (flags < 0)
+ return flags;
+
+ if (i2c_smbus_write_byte_data(client, M41T80_REG_FLAGS,
+ flags & ~M41T80_FLAGS_OF)) {
+ dev_err(&client->dev, "Unable to write flags register\n");
+ return -EIO;
+ }
+
return err;
}