diff options
| author | Keerthy <j-keerthy@ti.com> | 2016-06-01 13:49:07 +0300 |
|---|---|---|
| committer | Alexandre Belloni <alexandre.belloni@free-electrons.com> | 2016-07-09 11:24:44 +0300 |
| commit | e29385fab0bf94017fac130ee32f5bb2daf74417 (patch) | |
| tree | 8541a455ce5697bfc01ec92580995d06dda808c8 /drivers/rtc | |
| parent | cd9b518b98d3e989f523e63b2ffda78467a3679e (diff) | |
| download | linux-e29385fab0bf94017fac130ee32f5bb2daf74417.tar.xz | |
rtc: ds1307: Fix relying on reset value for weekday
The reset value of weekday is 0x1. This is wrong since
the reset values of the day/month/year make up to Jan 1 2001.
When computed weekday comes out to be Monday. On a scale
of 1-7(Sunday - Saturday) it should be 0x2. So we should not
be relying on the reset value.
Hence compute the wday using the current date/month/year values.
Check if reset wday is any different from the computed wday,
If different then set the wday which we computed using
date/month/year values.
Document Referred:
http://ww1.microchip.com/downloads/en/DeviceDoc/20002266F.pdf
Fixes: 1d1945d261a2af "drivers/rtc/rtc-ds1307.c: add alarm support for mcp7941x chips"
Signed-off-by: Keerthy <j-keerthy@ti.com>
Signed-off-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>
Diffstat (limited to 'drivers/rtc')
| -rw-r--r-- | drivers/rtc/rtc-ds1307.c | 28 |
1 files changed, 27 insertions, 1 deletions
diff --git a/drivers/rtc/rtc-ds1307.c b/drivers/rtc/rtc-ds1307.c index 821d9c089cdb..f25f7dce6e1f 100644 --- a/drivers/rtc/rtc-ds1307.c +++ b/drivers/rtc/rtc-ds1307.c @@ -602,6 +602,8 @@ static const struct rtc_class_ops ds13xx_rtc_ops = { * Alarm support for mcp794xx devices. */ +#define MCP794XX_REG_WEEKDAY 0x3 +#define MCP794XX_REG_WEEKDAY_WDAY_MASK 0x7 #define MCP794XX_REG_CONTROL 0x07 # define MCP794XX_BIT_ALM0_EN 0x10 # define MCP794XX_BIT_ALM1_EN 0x20 @@ -1231,13 +1233,16 @@ static int ds1307_probe(struct i2c_client *client, { struct ds1307 *ds1307; int err = -ENODEV; - int tmp; + int tmp, wday; struct chip_desc *chip = &chips[id->driver_data]; struct i2c_adapter *adapter = to_i2c_adapter(client->dev.parent); bool want_irq = false; bool ds1307_can_wakeup_device = false; unsigned char *buf; struct ds1307_platform_data *pdata = dev_get_platdata(&client->dev); + struct rtc_time tm; + unsigned long timestamp; + irq_handler_t irq_handler = ds1307_irq; static const int bbsqi_bitpos[] = { @@ -1526,6 +1531,27 @@ read_rtc: bin2bcd(tmp)); } + /* + * Some IPs have weekday reset value = 0x1 which might not correct + * hence compute the wday using the current date/month/year values + */ + ds1307_get_time(&client->dev, &tm); + wday = tm.tm_wday; + timestamp = rtc_tm_to_time64(&tm); + rtc_time64_to_tm(timestamp, &tm); + + /* + * Check if reset wday is different from the computed wday + * If different then set the wday which we computed using + * timestamp + */ + if (wday != tm.tm_wday) { + wday = i2c_smbus_read_byte_data(client, MCP794XX_REG_WEEKDAY); + wday = wday & ~MCP794XX_REG_WEEKDAY_WDAY_MASK; + wday = wday | (tm.tm_wday + 1); + i2c_smbus_write_byte_data(client, MCP794XX_REG_WEEKDAY, wday); + } + if (want_irq) { device_set_wakeup_capable(&client->dev, true); set_bit(HAS_ALARM, &ds1307->flags); |