Hi, On 01/06/2016 at 16:19:07 +0530, Keerthy wrote : > 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. >
Hum, what are the chances that the reset value is actually the correct date/time? Won't that be corrected after the first call to set_time? Until then, the date is not correct so, do we care anyway? Maybe I'm missing something here. > 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 <[email protected]> > --- > drivers/rtc/rtc-ds1307.c | 28 +++++++++++++++++++++++++++- > 1 file changed, 27 insertions(+), 1 deletion(-) > > diff --git a/drivers/rtc/rtc-ds1307.c b/drivers/rtc/rtc-ds1307.c > index 821d9c0..d9045cc 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); > -- > 1.9.1 -- Alexandre Belloni, Free Electrons Embedded Linux, Kernel and Android engineering http://free-electrons.com
