reset: Provide new single-function reset API

board_reset() replaces the existing common reset API. There is no common
distinction between reset types across platforms, hence, common code
could never decide which one to call.

Currently only hard_reset() is used by common code. We replace these
calls and provide a fall-back to the current hard_reset() implemen-
tation. The fall-back will be removed along with hard_reset() after the
transition of all boards.

Change-Id: I274a8cee9cb38226b5a0bdff6a847c74ef0b3128
Signed-off-by: Nico Huber <nico.h@gmx.de>
Reviewed-on: https://review.coreboot.org/29047
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Julius Werner <jwerner@chromium.org>
Reviewed-by: Aaron Durbin <adurbin@chromium.org>

src/device/root_device.c

@@ -147,7 +147,7 @@ static void root_dev_scan_bus(struct device *bus)
 static void root_dev_reset(struct bus *bus)
 {
 	printk(BIOS_INFO, "Resetting board...\n");
-	hard_reset();
+	board_reset();
 }
 
 #if IS_ENABLED(CONFIG_HAVE_ACPI_TABLES)

src/include/reset.h

@@ -1,7 +1,43 @@
 #ifndef RESET_H
 #define RESET_H
 
-/* Generic reset functions. Call from code that wants to trigger a reset. */
+/*
+ * Generic board reset function. Call from common code that
+ * wants to trigger a reset.
+ */
+__noreturn void board_reset(void);
+/*
+ * SoC or board specific implementation of the board reset.
+ *
+ * Implementations shall meet the following criteria:
+ *
+ *   o For vboot support, the TPM MUST be reset.
+ *
+ *   o All SoC/chipset blocks SHOULD be reset except for those
+ *     that are intentionally meant to survive reset (e.g. tomb-
+ *     stone registers and that sort of stuff).
+ *
+ *   o All external SoC pins SHOULD return to power-on reset values.
+ *
+ *   o The CPU MUST resume execution from power-on reset vector
+ *     (same as cold boot).
+ *
+ *   o Other board components (e.g. PCI, SDIO and stuff) SHOULD
+ *     be reset.
+ *
+ *   o USB SHOULD be power-cycled.
+ *
+ *   o Board components that are intended to be fully independent
+ *     from SoC (e.g. EC and EC-attached devices, the Cr50 on
+ *     Chromebooks) SHOULD NOT be reset.
+ *
+ * General recommendations:
+ *
+ *   o DRAM SHOULD NOT lose power if possible.
+ *
+ *   o Reset time SHOULD be minimized
+ */
+void do_board_reset(void);
 
 /* Super-hard reset specific to some Intel SoCs. */
 __noreturn void global_reset(void);

src/lib/Kconfig

@@ -1,3 +1,10 @@
+config MISSING_BOARD_RESET
+	bool
+	help
+	  Selected by boards that don't provide a do_board_reset()
+	  implementation. This activates a stub that logs the missing
+	  board reset and halts execution.
+
 config NO_EDID_FILL_FB
 	bool
 	default y if !MAINBOARD_DO_NATIVE_VGA_INIT

src/lib/prog_loaders.c

@@ -84,8 +84,7 @@ static void ramstage_cache_invalid(void)
 {
 	printk(BIOS_ERR, "ramstage cache invalid.\n");
 	if (IS_ENABLED(CONFIG_RESET_ON_INVALID_RAMSTAGE_CACHE)) {
-		hard_reset();
-		halt();
+		board_reset();
 	}
 }
 

src/lib/reset.c

@@ -18,6 +18,30 @@
 #include <halt.h>
 #include <reset.h>
 
+__noreturn void board_reset(void)
+{
+	printk(BIOS_INFO, "%s() called!\n", __func__);
+	dcache_clean_all();
+	do_board_reset();
+	halt();
+}
+
+#if IS_ENABLED(CONFIG_MISSING_BOARD_RESET)
+void do_board_reset(void)
+{
+	printk(BIOS_CRIT, "No board_reset implementation, hanging...\n");
+}
+#else
+/*
+ * Fall back to hard_reset() for a regression free transition.
+ * FIXME: Remove after everything is converted to board_reset().
+ */
+__weak void do_board_reset(void)
+{
+	hard_reset();
+}
+#endif
+
 __noreturn static void __hard_reset(void) {
 	if (IS_ENABLED(CONFIG_HAVE_HARD_RESET))
 		do_hard_reset();

src/security/vboot/Kconfig

@@ -18,7 +18,7 @@ config VBOOT
 	bool "Verify firmware with vboot."
 	default n
 	select VBOOT_MOCK_SECDATA if !TPM1 && !TPM2
-	depends on HAVE_HARD_RESET
+	depends on HAVE_HARD_RESET || !MISSING_BOARD_RESET
 	help
 	  Enabling VBOOT will use vboot to verify the components of the firmware
 	  (stages, payload, etc).

src/security/vboot/vboot_common.c

@@ -129,6 +129,5 @@ void vboot_reboot(void)
 	if (IS_ENABLED(CONFIG_CONSOLE_CBMEM_DUMP_TO_UART))
 		cbmem_dump_console();
 	vboot_platform_prepare_reboot();
-	hard_reset();
-	die("failed to reboot");
+	board_reset();
 }

src/vendorcode/google/chromeos/watchdog.c

@@ -52,5 +52,5 @@ void reboot_from_watchdog(void)
 {
 	printk(BIOS_INFO, "Last reset was watchdog, reboot again to reset TPM!\n");
 	mark_watchdog_tombstone();
-	hard_reset();
+	board_reset();
 }