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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 <andrew.smirnov@gmail.com>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
This commit is contained in:
Andrey Smirnov 2016-04-03 18:06:33 -07:00 committed by Sascha Hauer
parent 6587b56678
commit 750f53c399
1 changed files with 16 additions and 4 deletions
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20
drivers/rtc/rtc-ds1307.c
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@ -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]);
}