From 750f53c399143d35b4cf2b460cdead72d6f7cf9f Mon Sep 17 00:00:00 2001 From: Andrey Smirnov Date: Sun, 3 Apr 2016 18:06:33 -0700 Subject: ds1307: Configure ds1341 for lowest power mode Empirical observations show that configuring INTCN=1, ECLK=0, EGFIL=0, DOSF=1 on DS1341 put the chip in the mode where it draws the least amount fo current. Add code to configure DS1341 in such a way in case Barebox is the last code that runs on the processor before being shut down. Signed-off-by: Andrey Smirnov Signed-off-by: Sascha Hauer --- drivers/rtc/rtc-ds1307.c | 20 ++++++++++++++++---- 1 file changed, 16 insertions(+), 4 deletions(-) (limited to 'drivers/rtc') diff --git a/drivers/rtc/rtc-ds1307.c b/drivers/rtc/rtc-ds1307.c index a1cfed6795..726586af4a 100644 --- a/drivers/rtc/rtc-ds1307.c +++ b/drivers/rtc/rtc-ds1307.c @@ -68,6 +68,7 @@ enum ds_type { #define DS1337_REG_CONTROL 0x0e # define DS1337_BIT_nEOSC 0x80 # define DS1339_BIT_BBSQI 0x20 +# define DS1341_BIT_EGFIL 0x20 # define DS3231_BIT_BBSQW 0x40 /* same as BBSQI */ # define DS1337_BIT_RS2 0x10 # define DS1337_BIT_RS1 0x08 @@ -83,6 +84,7 @@ enum ds_type { # define DS1340_BIT_OSF 0x80 #define DS1337_REG_STATUS 0x0f # define DS1337_BIT_OSF 0x80 +# define DS1341_BIT_DOSF 0x40 # define DS1341_BIT_ECLK 0x04 # define DS1337_BIT_A2I 0x02 # define DS1337_BIT_A1I 0x01 @@ -333,12 +335,22 @@ static int ds1307_probe(struct device_d *dev) i2c_smbus_write_byte_data(client, DS1337_REG_CONTROL, ds1307->regs[0]); - /* - For the above to be true, DS1341 also has to have - ECLK bit set to 0 - */ if (ds1307->type == ds_1341) { + /* + * For the above to be true, DS1341 also has to have + * ECLK bit set to 0 + */ ds1307->regs[1] &= ~DS1341_BIT_ECLK; + + /* + * Let's set additionale RTC bits to + * facilitate maximum power saving. + */ + ds1307->regs[0] |= DS1341_BIT_DOSF; + ds1307->regs[0] &= ~DS1341_BIT_EGFIL; + + i2c_smbus_write_byte_data(client, DS1337_REG_CONTROL, + ds1307->regs[0]); i2c_smbus_write_byte_data(client, DS1337_REG_STATUS, ds1307->regs[1]); } -- cgit v1.2.3