[mask_rom] Clear the retention SRAM if the reset reason is POR
Signed-off-by: Michael Munday <mike.munday@lowrisc.org>
diff --git a/sw/device/silicon_creator/mask_rom/mask_rom.c b/sw/device/silicon_creator/mask_rom/mask_rom.c
index 222c87b..3a96741 100644
--- a/sw/device/silicon_creator/mask_rom/mask_rom.c
+++ b/sw/device/silicon_creator/mask_rom/mask_rom.c
@@ -18,6 +18,8 @@
#include "sw/device/silicon_creator/lib/base/sec_mmio.h"
#include "sw/device/silicon_creator/lib/drivers/keymgr.h"
#include "sw/device/silicon_creator/lib/drivers/lifecycle.h"
+#include "sw/device/silicon_creator/lib/drivers/retention_sram.h"
+#include "sw/device/silicon_creator/lib/drivers/rstmgr.h"
#include "sw/device/silicon_creator/lib/drivers/uart.h"
#include "sw/device/silicon_creator/lib/error.h"
#include "sw/device/silicon_creator/lib/shutdown.h"
@@ -64,6 +66,22 @@
shutdown_init(lc_state);
// Initiaize in-memory copy of the ePMP register configuration.
mask_rom_epmp_state_init(&epmp);
+
+ // Initialize the retention SRAM at power-on.
+ //
+ // The reset reason is treated as power-on if the POR bit is asserted
+ // regardless of whether or not any other reset reason bits are set. This is
+ // because we cannot guarantee that the retention SRAM was fully initialized
+ // if the device was reset before the POR bit was cleared.
+ //
+ // TODO(lowRISC/opentitan#7887): once the retention SRAM is initialized the
+ // reset reason should probably be saved into either main SRAM or the
+ // retention SRAM and the reset reason register cleared.
+ uint32_t reset_reasons = rstmgr_reason_get();
+ if (bitfield_bit32_read(reset_reasons, kRstmgrReasonPowerOn)) {
+ retention_sram_clear();
+ }
+
// Initialize pinmux configuration so we can use the UART.
pinmux_init();
// Configure UART0 as stdout.
@@ -72,7 +90,7 @@
.data = NULL,
.sink = uart_sink,
});
- // TODO: Clean device state based on reset reason (chip-specific startup).
+
// TODO: Bootstrap.
}
diff --git a/sw/device/silicon_creator/mask_rom/meson.build b/sw/device/silicon_creator/mask_rom/meson.build
index aa3fd75..2499f34 100644
--- a/sw/device/silicon_creator/mask_rom/meson.build
+++ b/sw/device/silicon_creator/mask_rom/meson.build
@@ -173,6 +173,8 @@
sw_silicon_creator_lib_driver_keymgr,
sw_silicon_creator_lib_driver_lifecycle,
sw_silicon_creator_lib_driver_pinmux,
+ sw_silicon_creator_lib_driver_retention_sram,
+ sw_silicon_creator_lib_driver_rstmgr,
sw_silicon_creator_lib_driver_uart,
sw_silicon_creator_lib_fake_deps,
sw_silicon_creator_lib_irq_asm,
