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>

1 files changed, 43 insertions, 1 deletions

diff --git a/arch/arm/mach-omap2/prm.h b/arch/arm/mach-omap2/prm.h
index 3e51c1d1575..c30ab5de8d1 100644
--- a/arch/arm/mach-omap2/prm.h
+++ b/arch/arm/mach-omap2/prm.h
@@ -52,16 +52,58 @@
 #define OMAP_POWERSTATE_SHIFT				0
 #define OMAP_POWERSTATE_MASK				(0x3 << 0)
 
+/*
+ * Standardized OMAP reset source bits
+ *
+ * To the extent these happen to match the hardware register bit
+ * shifts, it's purely coincidental.  Used by omap-wdt.c.
+ * OMAP_UNKNOWN_RST_SRC_ID_SHIFT is a special value, used whenever
+ * there are any bits remaining in the global PRM_RSTST register that
+ * haven't been identified, or when the PRM code for the current SoC
+ * doesn't know how to interpret the register.
+ */
+#define OMAP_GLOBAL_COLD_RST_SRC_ID_SHIFT			0
+#define OMAP_GLOBAL_WARM_RST_SRC_ID_SHIFT			1
+#define OMAP_SECU_VIOL_RST_SRC_ID_SHIFT				2
+#define OMAP_MPU_WD_RST_SRC_ID_SHIFT				3
+#define OMAP_SECU_WD_RST_SRC_ID_SHIFT				4
+#define OMAP_EXTWARM_RST_SRC_ID_SHIFT				5
+#define OMAP_VDD_MPU_VM_RST_SRC_ID_SHIFT			6
+#define OMAP_VDD_IVA_VM_RST_SRC_ID_SHIFT			7
+#define OMAP_VDD_CORE_VM_RST_SRC_ID_SHIFT			8
+#define OMAP_ICEPICK_RST_SRC_ID_SHIFT				9
+#define OMAP_ICECRUSHER_RST_SRC_ID_SHIFT			10
+#define OMAP_C2C_RST_SRC_ID_SHIFT				11
+#define OMAP_UNKNOWN_RST_SRC_ID_SHIFT				12
+
 #ifndef __ASSEMBLER__
 
 /**
+ * struct prm_reset_src_map - map register bitshifts to standard bitshifts
+ * @reg_shift: bitshift in the PRM reset source register
+ * @std_shift: bitshift equivalent in the standard reset source list
+ *
+ * The fields are signed because -1 is used as a terminator.
+ */
+struct prm_reset_src_map {
+	s8 reg_shift;
+	s8 std_shift;
+};
+
+/**
  * struct prm_ll_data - fn ptrs to per-SoC PRM function implementations
+ * @read_reset_sources: ptr to the Soc PRM-specific get_reset_source impl
  */
-struct prm_ll_data {};
+struct prm_ll_data {
+	u32 (*read_reset_sources)(void);
+};
 
 extern int prm_register(struct prm_ll_data *pld);
 extern int prm_unregister(struct prm_ll_data *pld);
 
+extern u32 prm_read_reset_sources(void);
+
 #endif
 
+
 #endif