Move flash persistent state to flash_common

Persistent state is needed by all platforms to hold the
protect-ro-at-boot flag.  STM32F100 and LM4 implementations were
near-identical, and are now common code (with one #ifdef to handle the
single place where they weren't).

STM32L doesn't use pstate yet, but it'll need to.  I can't simply
store the protect-ro-at-boot flag inside the WRP registers themselves
because they're still writable in EC-RW.  The change to STM32L to use
pstate is coming next.

BUG=chrome-os-partner:15613
BRANCH=none
TEST=build pit, link, spring; on link and spring, do

 - flashinfo -> (no flags)
 - enable WP (via screw or dut-control)
 - flashinfo -> wp_gpio_asserted
 - flashwp enable
 - flashinfo -> wp_gpio_asserted ro_at_boot
 - flashwp now
 - flashinfo -> wp_gpio_asserted ro_at_boot all_now (and possibly ro_now)
 - flashwp disable -> fails
 - flashinfo -> wp_gpio_asserted ro_at_boot all_now
 - reboot ap-off
 - flashinfo -> wp_gpio_asserted ro_at_boot ro_now
 - disable WP (via screw or dut-control)
 - reboot
 - flashinfo -> ro_at_boot
 - flashwp disable
 - flashinfo -> (no flags)

(Note that on Spring you'll need to 'forceen on' before enabling WP,
or the console will be disabled once you enable ro_at_boot and reboot.)

Change-Id: I415388b98ec8bf1d149803aaaa7fe8c7f3076c36
Signed-off-by: Randall Spangler <rspangler@chromium.org>
Reviewed-on: https://gerrit.chromium.org/gerrit/56064

1 files changed, 49 insertions, 0 deletions

diff --git a/include/flash.h b/include/flash.h
index fe592e3478..8969a56c8b 100644
--- a/include/flash.h
+++ b/include/flash.h
@@ -11,6 +11,23 @@
 #include "common.h"
 #include "ec_commands.h"  /* For EC_FLASH_PROTECT_* flags */
 
+/* Number of physical flash banks */
+#define PHYSICAL_BANKS (CONFIG_FLASH_PHYSICAL_SIZE / CONFIG_FLASH_BANK_SIZE)
+
+/* Read-only firmware offset and size in units of flash banks */
+#define RO_BANK_OFFSET (CONFIG_SECTION_RO_OFF / CONFIG_FLASH_BANK_SIZE)
+#define RO_BANK_COUNT  (CONFIG_SECTION_RO_SIZE / CONFIG_FLASH_BANK_SIZE)
+
+/* Read-write firmware offset and size in units of flash banks */
+#define RW_BANK_OFFSET (CONFIG_SECTION_RW_OFF / CONFIG_FLASH_BANK_SIZE)
+#define RW_BANK_COUNT  (CONFIG_SECTION_RW_SIZE / CONFIG_FLASH_BANK_SIZE)
+
+/* Persistent protection state flash offset / size / bank */
+#define PSTATE_OFFSET     CONFIG_SECTION_FLASH_PSTATE_OFF
+#define PSTATE_SIZE       CONFIG_SECTION_FLASH_PSTATE_SIZE
+#define PSTATE_BANK       (PSTATE_OFFSET / CONFIG_FLASH_BANK_SIZE)
+#define PSTATE_BANK_COUNT (PSTATE_SIZE / CONFIG_FLASH_BANK_SIZE)
+
 /*****************************************************************************/
 /* Low-level methods, for use by flash_common. */
 
@@ -71,6 +88,17 @@ int flash_physical_erase(int offset, int size);
 int flash_physical_get_protect(int bank);
 
 /**
+ * Set physical write protect status for the next boot.
+ *
+ * @param start_bank	Start bank
+ * @param bank_count	Number of banks to protect
+ * @param enable	Enable (non-zero) or disable (zero) protection
+ * @return non-zero if error.
+ */
+int flash_physical_set_protect_at_boot(int start_bank, int bank_count,
+				       int enable);
+
+/**
  * Force reload of flash protection bits.
  *
  * Some EC architectures (STM32L) only load the bits from option bytes at
@@ -82,6 +110,27 @@ int flash_physical_get_protect(int bank);
 int flash_physical_force_reload(void);
 
 /*****************************************************************************/
+/* Low-level persistent state code for use by flash modules. */
+
+/**
+ * Return non-zero if RO flash should be protected at boot.
+ */
+int flash_get_protect_ro_at_boot(void);
+
+/**
+ * Enable write protect for the read-only code.
+ *
+ * Once write protect is enabled, it will STAY enabled until the system is
+ * hard-rebooted with the hardware write protect pin deasserted.  If the write
+ * protect pin is deasserted, the protect setting is ignored, and the entire
+ * flash will be writable.
+ *
+ * @param enable        Enable write protection
+ * @return EC_SUCCESS, or nonzero if error.
+ */
+int flash_protect_ro_at_boot(int enable);
+
+/*****************************************************************************/
 /* High-level interface for use by other modules. */
 
 /**