ARM: bcm283x: Implement EFI RTS reset_system

The rpi has a pretty simple way of resetting the whole system. All it takes
is to poke a few registers at a well defined location in MMIO space.

This patch adds support for the EFI loader implementation to allow an OS to
reset and power off the system when we're outside of boot time.
Signed-off-by: NAlexander Graf <agraf@suse.de>

arch/arm/mach-bcm283x/include/mach/wdog.h

@@ -16,7 +16,7 @@
 struct bcm2835_wdog_regs {
 	u32 unknown0[7];
 	u32 rstc;
-	u32 unknown1;
+	u32 rsts;
 	u32 wdog;
 };
 

arch/arm/mach-bcm283x/reset.c

@@ -10,19 +10,66 @@
 #include <common.h>
 #include <asm/io.h>
 #include <asm/arch/wdog.h>
+#include <efi_loader.h>
 
 #define RESET_TIMEOUT 10
 
-void reset_cpu(ulong addr)
+/*
+ * The Raspberry Pi firmware uses the RSTS register to know which partiton
+ * to boot from. The partiton value is spread into bits 0, 2, 4, 6, 8, 10.
+ * Partiton 63 is a special partition used by the firmware to indicate halt.
+ */
+#define BCM2835_WDOG_RSTS_RASPBERRYPI_HALT	0x555
+
+__efi_runtime_data struct bcm2835_wdog_regs *wdog_regs =
+	(struct bcm2835_wdog_regs *)BCM2835_WDOG_PHYSADDR;
+
+void __efi_runtime reset_cpu(ulong addr)
 {
-	struct bcm2835_wdog_regs *regs =
-		(struct bcm2835_wdog_regs *)BCM2835_WDOG_PHYSADDR;
 	uint32_t rstc;
 
-	rstc = readl(&regs->rstc);
+	rstc = readl(&wdog_regs->rstc);
 	rstc &= ~BCM2835_WDOG_RSTC_WRCFG_MASK;
 	rstc |= BCM2835_WDOG_RSTC_WRCFG_FULL_RESET;
 
-	writel(BCM2835_WDOG_PASSWORD | RESET_TIMEOUT, &regs->wdog);
-	writel(BCM2835_WDOG_PASSWORD | rstc, &regs->rstc);
+	writel(BCM2835_WDOG_PASSWORD | RESET_TIMEOUT, &wdog_regs->wdog);
+	writel(BCM2835_WDOG_PASSWORD | rstc, &wdog_regs->rstc);
+}
+
+#ifdef CONFIG_EFI_LOADER
+
+void __efi_runtime EFIAPI efi_reset_system(
+			enum efi_reset_type reset_type,
+			efi_status_t reset_status,
+			unsigned long data_size, void *reset_data)
+{
+	u32 val;
+
+	switch (reset_type) {
+	case EFI_RESET_COLD:
+	case EFI_RESET_WARM:
+		reset_cpu(0);
+		break;
+	case EFI_RESET_SHUTDOWN:
+		/*
+		 * We set the watchdog hard reset bit here to distinguish this reset
+		 * from the normal (full) reset. bootcode.bin will not reboot after a
+		 * hard reset.
+		 */
+		val = readl(&wdog_regs->rsts);
+		val |= BCM2835_WDOG_PASSWORD;
+		val |= BCM2835_WDOG_RSTS_RASPBERRYPI_HALT;
+		writel(val, &wdog_regs->rsts);
+		reset_cpu(0);
+		break;
+	}
+
+	while (1) { }
 }
+
+void efi_reset_system_init(void)
+{
+	efi_add_runtime_mmio(&wdog_regs, sizeof(*wdog_regs));
+}
+
+#endif