arm: mach-k3: am64x: Implement get_reset_reason()

Implement get_reset_reason() for AM64x to enable reporting of the reset
cause in the cpuinfo output.

Notice that the AM64x does not support dedicated reset cause bits for
WDT and PORZ as the AM62x does.

An explanation of this difference is not part of the technical reference
manual and remains unclear.

Signed-off-by: Steffen Kothe <steffen.kothe@skothe.net>
Reviewed-by: Bryan Brattlof <bb@ti.com>

diff --git a/arch/arm/mach-k3/am64x/boot.c b/arch/arm/mach-k3/am64x/boot.c
index ce8ae941be6f598b562d121ed92b0a4733b12a09..f88f92b9f23aca6dfd7810bed00833bb52a789a9 100644 (file)
--- a/arch/arm/mach-k3/am64x/boot.c
+++ b/arch/arm/mach-k3/am64x/boot.c
@@ -103,3 +103,39 @@ u32 get_boot_device(void)
 
        return bootmedia;
 }
+
+const char *get_reset_reason(void)
+{
+       u32 reset_reason = readl(CTRLMMR_MCU_RST_SRC);
+
+       /* After reading reset source register, software must clear it */
+       if (reset_reason)
+               writel(reset_reason, CTRLMMR_MCU_RST_SRC);
+
+       if (reset_reason == 0 ||
+          (reset_reason & (RST_SRC_SW_MAIN_POR_FROM_MAIN |
+                           RST_SRC_SW_MAIN_POR_FROM_MCU)))
+               return "POR";
+
+       if (reset_reason & (RST_SRC_SAFETY_ERR | RST_SRC_MAIN_ESM_ERR))
+               return "ESM";
+
+       if (reset_reason & (RST_SRC_SW_MAIN_WARM_FROM_MAIN |
+                           RST_SRC_SW_MAIN_WARM_FROM_MCU  |
+                           RST_SRC_SW_MCU_WARM_RST))
+               return "RST";
+
+       if (reset_reason & (RST_SRC_SMS_WARM_RST | RST_SRC_SMS_COLD_RST))
+               return "DMSC";
+
+       if (reset_reason & RST_SRC_DEBUG_RST)
+               return "JTAG";
+
+       if (reset_reason & RST_SRC_THERMAL_RST)
+               return "THERMAL";
+
+       if (reset_reason & (RST_SRC_MAIN_RESET_PIN | RST_SRC_MCU_RESET_PIN))
+               return "PIN";
+
+       return "UNKNOWN";
+}