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, 68 insertions, 0 deletions

diff --git a/arch/arm/mach-omap2/prm2xxx.c b/arch/arm/mach-omap2/prm2xxx.c
index 9cdb4e5e3d80..e2860f9c111d 100644
--- a/arch/arm/mach-omap2/prm2xxx.c
+++ b/arch/arm/mach-omap2/prm2xxx.c
@@ -29,6 +29,46 @@
 #include "cm2xxx_3xxx.h"
 #include "prm-regbits-24xx.h"
 
+/*
+ * omap2xxx_prm_reset_src_map - map from bits in the PRM_RSTST_WKUP
+ *   hardware register (which are specific to the OMAP2xxx SoCs) to
+ *   reset source ID bit shifts (which is an OMAP SoC-independent
+ *   enumeration)
+ */
+static struct prm_reset_src_map omap2xxx_prm_reset_src_map[] = {
+        { OMAP_GLOBALCOLD_RST_SHIFT, OMAP_GLOBAL_COLD_RST_SRC_ID_SHIFT },
+        { OMAP_GLOBALWARM_RST_SHIFT, OMAP_GLOBAL_WARM_RST_SRC_ID_SHIFT },
+        { OMAP24XX_SECU_VIOL_RST_SHIFT, OMAP_SECU_VIOL_RST_SRC_ID_SHIFT },
+        { OMAP24XX_MPU_WD_RST_SHIFT, OMAP_MPU_WD_RST_SRC_ID_SHIFT },
+        { OMAP24XX_SECU_WD_RST_SHIFT, OMAP_SECU_WD_RST_SRC_ID_SHIFT },
+        { OMAP24XX_EXTWMPU_RST_SHIFT, OMAP_EXTWARM_RST_SRC_ID_SHIFT },
+        { -1, -1 },
+};
+
+/**
+ * omap2xxx_prm_read_reset_sources - return the last SoC reset source
+ *
+ * Return a u32 representing the last reset sources of the SoC.  The
+ * returned reset source bits are standardized across OMAP SoCs.
+ */
+static u32 omap2xxx_prm_read_reset_sources(void)
+{
+        struct prm_reset_src_map *p;
+        u32 r = 0;
+        u32 v;
+
+        v = omap2_prm_read_mod_reg(WKUP_MOD, OMAP2_RM_RSTST);
+
+        p = omap2xxx_prm_reset_src_map;
+        while (p->reg_shift >= 0 && p->std_shift >= 0) {
+                if (v & (1 << p->reg_shift))
+                        r |= 1 << p->std_shift;
+                p++;
+        }
+
+        return r;
+}
+
 int omap2xxx_clkdm_sleep(struct clockdomain *clkdm)
 {
         omap2_prm_set_mod_reg_bits(OMAP24XX_FORCESTATE_MASK,
@@ -56,3 +96,31 @@ struct pwrdm_ops omap2_pwrdm_operations = {
         .pwrdm_read_mem_retst   = omap2_pwrdm_read_mem_retst,
         .pwrdm_wait_transition  = omap2_pwrdm_wait_transition,
 };
+
+/*
+ *
+ */
+
+static struct prm_ll_data omap2xxx_prm_ll_data = {
+        .read_reset_sources = &omap2xxx_prm_read_reset_sources,
+};
+
+static int __init omap2xxx_prm_init(void)
+{
+        if (!cpu_is_omap24xx())
+                return 0;
+
+        return prm_register(&omap2xxx_prm_ll_data);
+}
+subsys_initcall(omap2xxx_prm_init);
+
+static void __exit omap2xxx_prm_exit(void)
+{
+        if (!cpu_is_omap24xx())
+                return;
+
+        /* Should never happen */
+        WARN(prm_unregister(&omap2xxx_prm_ll_data),
+             "%s: prm_ll_data function pointer mismatch\n", __func__);
+}
+__exitcall(omap2xxx_prm_exit);