ARM: OMAP2+: PRM: create PRM reset source API for the watchdog timer driver

The OMAP watchdog timer driver needs to determine what caused the SoC
to reset for its GETBOOTSTATUS ioctl.  So, define a set of standard
reset sources across OMAP SoCs.  For OMAP2xxx, 3xxx, and 4xxx SoCs,
define mappings from the SoC-specific reset source register bits to
the standardized reset source IDs.  Create SoC-specific PRM functions
that read the appropriate per-SoC register and use the mapping to
return the standardized reset bits.  Register the SoC-specific PRM
functions with the common PRM code via prm_register().  Create a
function in the common PRM code, prm_read_reset_sources(), that
calls the SoC-specific function, registered during boot.

This patch does not yet handle some SoCs, such as AM33xx.  Those SoCs
were not handled by the code this will replace.

Signed-off-by: Paul Walmsley <paul@pwsan.com>
diff --git a/arch/arm/mach-omap2/prm-regbits-34xx.h b/arch/arm/mach-omap2/prm-regbits-34xx.h
index 073d4db..838b594 100644
--- a/arch/arm/mach-omap2/prm-regbits-34xx.h
+++ b/arch/arm/mach-omap2/prm-regbits-34xx.h
@@ -509,15 +509,25 @@
 #define OMAP3430_RSTTIME1_MASK				(0xff << 0)
 
 /* PRM_RSTST */
+#define OMAP3430_ICECRUSHER_RST_SHIFT			10
 #define OMAP3430_ICECRUSHER_RST_MASK			(1 << 10)
+#define OMAP3430_ICEPICK_RST_SHIFT			9
 #define OMAP3430_ICEPICK_RST_MASK			(1 << 9)
+#define OMAP3430_VDD2_VOLTAGE_MANAGER_RST_SHIFT		8
 #define OMAP3430_VDD2_VOLTAGE_MANAGER_RST_MASK		(1 << 8)
+#define OMAP3430_VDD1_VOLTAGE_MANAGER_RST_SHIFT		7
 #define OMAP3430_VDD1_VOLTAGE_MANAGER_RST_MASK		(1 << 7)
+#define OMAP3430_EXTERNAL_WARM_RST_SHIFT		6
 #define OMAP3430_EXTERNAL_WARM_RST_MASK			(1 << 6)
+#define OMAP3430_SECURE_WD_RST_SHIFT			5
 #define OMAP3430_SECURE_WD_RST_MASK			(1 << 5)
+#define OMAP3430_MPU_WD_RST_SHIFT			4
 #define OMAP3430_MPU_WD_RST_MASK			(1 << 4)
+#define OMAP3430_SECURITY_VIOL_RST_SHIFT		3
 #define OMAP3430_SECURITY_VIOL_RST_MASK			(1 << 3)
+#define OMAP3430_GLOBAL_SW_RST_SHIFT			1
 #define OMAP3430_GLOBAL_SW_RST_MASK			(1 << 1)
+#define OMAP3430_GLOBAL_COLD_RST_SHIFT			0
 #define OMAP3430_GLOBAL_COLD_RST_MASK			(1 << 0)
 
 /* PRM_VOLTCTRL */