cr50: use dedicated region for info1 accesses

The INFO1 flash space is used for various purposes (endorsement key
seed, Board ID and flags, serial number, etc.).

Accessing these spaces in INFO1 is accompanied by managing the flash
region registers, each time opening a window of the appropriate size,
with appropriate permissions, etc,

In fact none of these spaces contain a secret, to simplify things and
preventing situations when concurrent accesses change the flash range
window settings lets dedicate previously unused Region 7 register file
to providing always open read access to INFO1.

Write access will be enabled/disabled as required. In prod images
write accesses will always happen from the vendor command context. In
DBG images CLI commands will also have write access to INFO1.

INFO1 window is accessed by other H1 based devices as well, this is
why it is necessary to enable the window in the common chip code.

BRANCH=cr50, cr50-mp
BUG=b:138256149
TEST=the firmware_Cr50SetBoardId test now passes on Mistral.

Cq-Depend: chrome-internal:1577866, chrome-internal:1581327
Change-Id: Id27348f3b04191f1b3b60fd838d06009f756baa2
Signed-off-by: Vadim Bendebury <vbendeb@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/1730147
Legacy-Commit-Queue: Commit Bot <commit-bot@chromium.org>
Reviewed-by: Mary Ruthven <mruthven@chromium.org>

1 files changed, 12 insertions, 54 deletions

diff --git a/chip/g/flash.c b/chip/g/flash.c
index 07573f7fd9..443ab23efe 100644
--- a/chip/g/flash.c
+++ b/chip/g/flash.c
@@ -103,6 +103,13 @@ int flash_pre_init(void)
 	GWRITE_FIELD(GLOBALSEC, FLASH_REGION5_CTRL, RD_EN, 1);
 	flash_log_register_flash_control_callback(flash_log_space_control);
 #endif
+
+	/* Create a flash region window for INFO1 access. */
+	GREG32(GLOBALSEC, FLASH_REGION7_BASE_ADDR) = FLASH_INFO_MEMORY_BASE;
+	GREG32(GLOBALSEC, FLASH_REGION7_SIZE) = FLASH_INFO_SIZE - 1;
+	GWRITE_FIELD(GLOBALSEC, FLASH_REGION7_CTRL, EN, 1);
+	GWRITE_FIELD(GLOBALSEC, FLASH_REGION7_CTRL, RD_EN, 1);
+
 	return EC_SUCCESS;
 }
 
@@ -388,62 +395,14 @@ int flash_physical_info_read_word(int byte_offset, uint32_t *dst)
 	return ret;
 }
 
-/*
- * Verify that the range's size is power of 2, the range offset is aligned by
- * size, and the range does not cross the INFO space boundary.
- */
-static int valid_info_range(uint32_t offset, size_t size)
+void flash_info_write_enable(void)
 {
-	if (!size || (size & (size - 1)))
-		return 0;
-
-	if (offset & (size - 1))
-		return 0;
-
-	if ((offset + size) > FLASH_INFO_SIZE)
-		return 0;
-
-	return 1;
-
-}
-
-/* Write access is a superset of read access. */
-static int flash_info_configure_access(uint32_t offset,
-				       size_t size, int write_mode)
-{
-	int mask;
-
-	if (!valid_info_range(offset, size))
-		return EC_ERROR_INVAL;
-
-	mask = GREG32(GLOBALSEC, FLASH_REGION6_CTRL);
-	mask |= GC_GLOBALSEC_FLASH_REGION6_CTRL_EN_MASK |
-		GC_GLOBALSEC_FLASH_REGION6_CTRL_RD_EN_MASK;
-	if (write_mode)
-		mask |= GC_GLOBALSEC_FLASH_REGION6_CTRL_WR_EN_MASK;
-
-	GREG32(GLOBALSEC, FLASH_REGION6_BASE_ADDR) =
-		FLASH_INFO_MEMORY_BASE + offset;
-
-	GREG32(GLOBALSEC, FLASH_REGION6_SIZE) = size - 1;
-	GREG32(GLOBALSEC, FLASH_REGION6_CTRL) = mask;
-
-	return EC_SUCCESS;
-}
-
-int flash_info_read_enable(uint32_t offset, size_t size)
-{
-	return flash_info_configure_access(offset, size, 0);
-}
-
-int flash_info_write_enable(uint32_t offset, size_t size)
-{
-	return flash_info_configure_access(offset, size, 1);
+	GWRITE_FIELD(GLOBALSEC, FLASH_REGION7_CTRL, WR_EN, 1);
 }
 
 void flash_info_write_disable(void)
 {
-	GWRITE_FIELD(GLOBALSEC, FLASH_REGION6_CTRL, WR_EN, 0);
+	GWRITE_FIELD(GLOBALSEC, FLASH_REGION7_CTRL, WR_EN, 0);
 }
 
 int flash_info_physical_write(int byte_offset, int num_bytes, const char *data)
@@ -516,9 +475,6 @@ static int command_erase_flash_info(int argc, char **argv)
 		return rv;
 	}
 
-	flash_info_read_enable(0, 2048);
-	flash_info_write_enable(0, 2048);
-
 	/* Read the entire info1. */
 	p = (uint32_t *)info1;
 	for (i = 0; i < (sizeof(*info1) / sizeof(*p)); i++) {
@@ -577,6 +533,8 @@ static int command_erase_flash_info(int argc, char **argv)
 
 	mutex_lock(&flash_mtx);
 
+	flash_info_write_enable();
+
 	rv = do_flash_op(OP_ERASE_BLOCK, 1, 0, 512);
 
 	mutex_unlock(&flash_mtx);