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rtc: ds1305/ds1306 driver

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Support the Dallas/Maxim DS1305 and DS1306 RTC chips.  These use SPI, and
support alarms, NVRAM, and a trickle charger for use when their backup
power supply is a supercap or rechargeable cell.

This basic driver doesn't yet support suspend/resume or wakealarms.

Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Cc: Alessandro Zummo <a.zummo@towertech.it>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
David Brownell 2008-07-23 21:30:36 -07:00 • committed by Linus Torvalds
commit 53e84b672c
4 changed files with 893 additions and 0 deletions
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35
include/linux/spi/ds1305.h Normal file
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#ifndef __LINUX_SPI_DS1305_H
#define __LINUX_SPI_DS1305_H
/*
* One-time configuration for ds1305 and ds1306 RTC chips.
*
* Put a pointer to this in spi_board_info.platform_data if you want to
* be sure that Linux (re)initializes this as needed ... after losing
* backup power, and potentially on the first boot.
*/
struct ds1305_platform_data {
/* Trickle charge configuration: it's OK to leave out the MAGIC
* bitmask; mask in either DS1 or DS2, and then one of 2K/4k/8K.
*/
#define DS1305_TRICKLE_MAGIC 0xa0
#define DS1305_TRICKLE_DS2 0x08 /* two diodes */
#define DS1305_TRICKLE_DS1 0x04 /* one diode */
#define DS1305_TRICKLE_2K 0x01 /* 2 KOhm resistance */
#define DS1305_TRICKLE_4K 0x02 /* 4 KOhm resistance */
#define DS1305_TRICKLE_8K 0x03 /* 8 KOhm resistance */
u8 trickle;
/* set only on ds1306 parts */
bool is_ds1306;
/* ds1306 only: enable 1 Hz output */
bool en_1hz;
/* REVISIT: the driver currently expects nINT0 to be wired
* as the alarm IRQ. ALM1 may also need to be set up ...
*/
};
#endif /* __LINUX_SPI_DS1305_H */