[PATCH 01/10] aspeed/smc: Add watchdog Control/Status Registers

[Cédric Le Goater]

The Aspeed SoCs have a dual boot function for firmware fail-over
recovery. The system auto-reboots from the second flash if the main
flash does not boot sucessfully within a certain amount of time. This
function is called alternate boot (ABR) in the FMC controllers.

On AST2400/AST2500, ABR is enabled by hardware strapping in SCU70 to
enable the 2nd watchdog timer, on AST2600, through register SCU510.
If the boot on the the main flash succeeds, the firmware should
disable the 2nd watchdog timer. If not, the BMC is reset and the CE0
and CE1 mappings are swapped to restart the BMC from the 2nd flash.

On the AST2600, the registers controlling the 2nd watchdog timer were
moved from the watchdog register to the FMC controller. Add simple
read/write handlers for these to let the FW disable the 2nd watchdog
without error.

Reported-by: Peter Delevoryas <pdel@fb.com>
Signed-off-by: Cédric Le Goater <clg@kaod.org>
---
 hw/ssi/aspeed_smc.c | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

diff --git a/hw/ssi/aspeed_smc.c b/hw/ssi/aspeed_smc.c
index 331a2c544635..c9990f069ea4 100644
--- a/hw/ssi/aspeed_smc.c
+++ b/hw/ssi/aspeed_smc.c
@@ -124,6 +124,13 @@
 /* SPI dummy cycle data */
 #define R_DUMMY_DATA      (0x54 / 4)
 
+/* FMC_WDT2 Control/Status Register for Alternate Boot (AST2600) */
+#define R_FMC_WDT2_CTRL   (0x64 / 4)
+#define   FMC_WDT2_CTRL_ALT_BOOT_MODE    BIT(6) /* O: 2 chips 1: 1 chip */
+#define   FMC_WDT2_CTRL_SINGLE_BOOT_MODE BIT(5)
+#define   FMC_WDT2_CTRL_BOOT_SOURCE      BIT(4) /* O: primary 1: alternate */
+#define   FMC_WDT2_CTRL_EN               BIT(0)
+
 /* DMA Control/Status Register */
 #define R_DMA_CTRL        (0x80 / 4)
 #define   DMA_CTRL_REQUEST      (1 << 31)
@@ -263,12 +270,18 @@ static void aspeed_2600_smc_dma_ctrl(AspeedSMCState *s, 
uint32_t value);
 
 #define ASPEED_SMC_FEATURE_DMA       0x1
 #define ASPEED_SMC_FEATURE_DMA_GRANT 0x2
+#define ASPEED_SMC_FEATURE_WDT_CONTROL 0x4
 
 static inline bool aspeed_smc_has_dma(const AspeedSMCState *s)
 {
     return !!(s->ctrl->features & ASPEED_SMC_FEATURE_DMA);
 }
 
+static inline bool aspeed_smc_has_wdt_control(const AspeedSMCState *s)
+{
+    return !!(s->ctrl->features & ASPEED_SMC_FEATURE_WDT_CONTROL);
+}
+
 static const AspeedSMCController controllers[] = {
     {
         .name              = "aspeed.smc-ast2400",
@@ -1019,6 +1032,7 @@ static uint64_t aspeed_smc_read(void *opaque, hwaddr 
addr, unsigned int size)
         addr == R_CE_CMD_CTRL ||
         addr == R_INTR_CTRL ||
         addr == R_DUMMY_DATA ||
+        (aspeed_smc_has_wdt_control(s) && addr == R_FMC_WDT2_CTRL) ||
         (aspeed_smc_has_dma(s) && addr == R_DMA_CTRL) ||
         (aspeed_smc_has_dma(s) && addr == R_DMA_FLASH_ADDR) ||
         (aspeed_smc_has_dma(s) && addr == R_DMA_DRAM_ADDR) ||
@@ -1350,6 +1364,8 @@ static void aspeed_smc_write(void *opaque, hwaddr addr, 
uint64_t data,
         s->regs[addr] = value & 0xff;
     } else if (addr == R_DUMMY_DATA) {
         s->regs[addr] = value & 0xff;
+    } else if (aspeed_smc_has_wdt_control(s) && addr == R_FMC_WDT2_CTRL) {
+        s->regs[addr] = value & 0xb;
     } else if (addr == R_INTR_CTRL) {
         s->regs[addr] = value;
     } else if (aspeed_smc_has_dma(s) && addr == R_DMA_CTRL) {
-- 
2.31.1