ARM: tegra: Support reboot modes

From: Thierry Reding <[email protected]>

The boot ROM on Tegra SoCs supports booting into forced recovery mode (RCM) by setting a bit in the PMC scratch register 0. Similarily, the Android bootloader examines some of the bits in this register to disable autoboot or enter recovery mode.

Support these modes by setting the corresponding bits depending on the specified reboot command (forced-recovery, bootloader, recovery). Recent systemd-based distributions allow this to be specified using an optional argument to the reboot command.

Signed-off-by Thierry Reding <[email protected]>

---
 arch/arm/mach-tegra/pmc.c | 24 ++++++++++++++++++++++++
 1 file changed, 24 insertions(+)

arch/arm/mach-tegra/pmc.c +24 -1

index fb7920201ab4..7c7123e7557b 100644
@@ -41,6 +41,14 @@
 #define PMC_REMOVE_CLAMPING            0x34
 #define PMC_PWRGATE_STATUS             0x38
 
+#define PMC_SCRATCH0                   0x50
+#define PMC_SCRATCH0_MODE_RECOVERY     (1 << 31)
+#define PMC_SCRATCH0_MODE_BOOTLOADER   (1 << 30)
+#define PMC_SCRATCH0_MODE_RCM          (1 << 1)
+#define PMC_SCRATCH0_MODE_MASK         (PMC_SCRATCH0_MODE_RECOVERY | \
+                                        PMC_SCRATCH0_MODE_BOOTLOADER | \
+                                        PMC_SCRATCH0_MODE_RCM)
+
 #define PMC_CPUPWRGOOD_TIMER   0xc8
 #define PMC_CPUPWROFF_TIMER    0xcc
 

@@ -165,6 +173,22 @@ void tegra_pmc_restart(enum reboot_mode mode, const char *cmd)
 {
        u32 val;
 
+       val = tegra_pmc_readl(PMC_SCRATCH0);
+       val &= ~PMC_SCRATCH0_MODE_MASK;
+
+       if (cmd) {
+               if (strcmp(cmd, "recovery") == 0)
+                       val |= PMC_SCRATCH0_MODE_RECOVERY;
+
+               if (strcmp(cmd, "bootloader") == 0)
+                       val |= PMC_SCRATCH0_MODE_BOOTLOADER;
+
+               if (strcmp(cmd, "forced-recovery") == 0)
+                       val |= PMC_SCRATCH0_MODE_RCM;
+       }
+
+       tegra_pmc_writel(val, PMC_SCRATCH0);
+
        val = tegra_pmc_readl(0);
        val |= 0x10;
        tegra_pmc_writel(val, 0);
--

1.9.2

From: Thierry Reding <[email protected]>

The boot ROM on Tegra SoCs supports booting into forced recovery mode (RCM) by setting a bit in the PMC scratch register 0. Similarily, the Android bootloader examines some of the bits in this register to disable autoboot or enter recovery mode.

Support these modes by setting the corresponding bits depending on the specified reboot command (forced-recovery, bootloader, recovery). Recent systemd-based distributions allow this to be specified using an optional argument to the reboot command.