w1: ds2760_battery: add support for sleep mode feature

This adds support for ds2760's sleep mode feature. With this feature
enabled, the chip enters a deep sleep mode and disconnects from the
battery when the w1 line is held down for more than 2 seconds.

This new behaviour can be switched on and off using a new module
parameter.

Signed-off-by: Daniel Mack <daniel@caiaq.de>
Cc: Szabolcs Gyurko <szabolcs.gyurko@tlt.hu>
Acked-by: Matt Reimer <mreimer@vpop.net>
Acked-by: Evgeniy Polyakov <zbr@ioremap.net>
Signed-off-by: Anton Vorontsov <cbouatmailru@gmail.com>

drivers/w1/slaves/w1_ds2760.h

@@ -25,6 +25,10 @@
 
 #define DS2760_PROTECTION_REG		0x00
 #define DS2760_STATUS_REG		0x01
+	#define DS2760_STATUS_IE	(1 << 2)
+	#define DS2760_STATUS_SWEN	(1 << 3)
+	#define DS2760_STATUS_RNAOP	(1 << 4)
+	#define DS2760_STATUS_PMOD	(1 << 5)
 #define DS2760_EEPROM_REG		0x07
 #define DS2760_SPECIAL_FEATURE_REG	0x08
 #define DS2760_VOLTAGE_MSB		0x0c
@@ -38,6 +42,7 @@
 #define DS2760_EEPROM_BLOCK0		0x20
 #define DS2760_ACTIVE_FULL		0x20
 #define DS2760_EEPROM_BLOCK1		0x30
+#define DS2760_STATUS_WRITE_REG		0x31
 #define DS2760_RATED_CAPACITY		0x32
 #define DS2760_CURRENT_OFFSET_BIAS	0x33
 #define DS2760_ACTIVE_EMPTY		0x3b