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, 80 insertions, 3 deletions

diff --git a/arch/arm/mach-omap2/prm44xx.c b/arch/arm/mach-omap2/prm44xx.c
index 48d91930796d..a799e9552fbf 100644
--- a/arch/arm/mach-omap2/prm44xx.c
+++ b/arch/arm/mach-omap2/prm44xx.c
@@ -1,7 +1,7 @@
 /*
  * OMAP4 PRM module functions
  *
- * Copyright (C) 2011 Texas Instruments, Inc.
+ * Copyright (C) 2011-2012 Texas Instruments, Inc.
  * Copyright (C) 2010 Nokia Corporation
  * Benoît Cousson
  * Paul Walmsley
@@ -30,6 +30,8 @@
 #include "prminst44xx.h"
 #include "powerdomain.h"
 
+/* Static data */
+
 static const struct omap_prcm_irq omap4_prcm_irqs[] = {
         OMAP_PRCM_IRQ("wkup",   0,      0),
         OMAP_PRCM_IRQ("io",     9,      1),
@@ -48,6 +50,33 @@ static struct omap_prcm_irq_setup omap4_prcm_irq_setup = {
         .restore_irqen          = &omap44xx_prm_restore_irqen,
 };
 
+/*
+ * omap44xx_prm_reset_src_map - map from bits in the PRM_RSTST
+ *   hardware register (which are specific to OMAP44xx SoCs) to reset
+ *   source ID bit shifts (which is an OMAP SoC-independent
+ *   enumeration)
+ */
+static struct prm_reset_src_map omap44xx_prm_reset_src_map[] = {
+        { OMAP4430_RST_GLOBAL_WARM_SW_SHIFT,
+          OMAP_GLOBAL_WARM_RST_SRC_ID_SHIFT },
+        { OMAP4430_RST_GLOBAL_COLD_SW_SHIFT,
+          OMAP_GLOBAL_COLD_RST_SRC_ID_SHIFT },
+        { OMAP4430_MPU_SECURITY_VIOL_RST_SHIFT,
+          OMAP_SECU_VIOL_RST_SRC_ID_SHIFT },
+        { OMAP4430_MPU_WDT_RST_SHIFT, OMAP_MPU_WD_RST_SRC_ID_SHIFT },
+        { OMAP4430_SECURE_WDT_RST_SHIFT, OMAP_SECU_WD_RST_SRC_ID_SHIFT },
+        { OMAP4430_EXTERNAL_WARM_RST_SHIFT, OMAP_EXTWARM_RST_SRC_ID_SHIFT },
+        { OMAP4430_VDD_MPU_VOLT_MGR_RST_SHIFT,
+          OMAP_VDD_MPU_VM_RST_SRC_ID_SHIFT },
+        { OMAP4430_VDD_IVA_VOLT_MGR_RST_SHIFT,
+          OMAP_VDD_IVA_VM_RST_SRC_ID_SHIFT },
+        { OMAP4430_VDD_CORE_VOLT_MGR_RST_SHIFT,
+          OMAP_VDD_CORE_VM_RST_SRC_ID_SHIFT },
+        { OMAP4430_ICEPICK_RST_SHIFT, OMAP_ICEPICK_RST_SRC_ID_SHIFT },
+        { OMAP4430_C2C_RST_SHIFT, OMAP_C2C_RST_SRC_ID_SHIFT },
+        { -1, -1 },
+};
+
 /* PRM low-level functions */
 
 /* Read a register in a CM/PRM instance in the PRM module */
@@ -293,6 +322,31 @@ static void __init omap44xx_prm_enable_io_wakeup(void)
                                     OMAP4_PRM_IO_PMCTRL_OFFSET);
 }
 
+/**
+ * omap44xx_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 omap44xx_prm_read_reset_sources(void)
+{
+        struct prm_reset_src_map *p;
+        u32 r = 0;
+        u32 v;
+
+        v = omap4_prm_read_inst_reg(OMAP4430_PRM_OCP_SOCKET_INST,
+                                    OMAP4_RM_RSTST);
+
+        p = omap44xx_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;
+}
+
 /* Powerdomain low-level functions */
 
 static int omap4_pwrdm_set_next_pwrst(struct powerdomain *pwrdm, u8 pwrst)
@@ -555,14 +609,37 @@ struct pwrdm_ops omap4_pwrdm_operations = {
         .pwrdm_wait_transition  = omap4_pwrdm_wait_transition,
 };
 
+/*
+ * XXX document
+ */
+static struct prm_ll_data omap44xx_prm_ll_data = {
+        .read_reset_sources = &omap44xx_prm_read_reset_sources,
+};
 
-static int __init omap4xxx_prm_init(void)
+static int __init omap44xx_prm_init(void)
 {
+        int ret;
+
         if (!cpu_is_omap44xx())
                 return 0;
 
+        ret = prm_register(&omap44xx_prm_ll_data);
+        if (ret)
+                return ret;
+
         omap44xx_prm_enable_io_wakeup();
 
         return omap_prcm_register_chain_handler(&omap4_prcm_irq_setup);
 }
-subsys_initcall(omap4xxx_prm_init);
+subsys_initcall(omap44xx_prm_init);
+
+static void __exit omap44xx_prm_exit(void)
+{
+        if (!cpu_is_omap44xx())
+                return;
+
+        /* Should never happen */
+        WARN(prm_unregister(&omap44xx_prm_ll_data),
+             "%s: prm_ll_data function pointer mismatch\n", __func__);
+}
+__exitcall(omap44xx_prm_exit);