[PATCH v4] mtd: cfi: respect reg address length

Nuno Sá nuno.sa at analog.com
Thu May 11 13:19:50 CEST 2023

flash_get_size() will get the flash size from the device itself and go
through all erase regions to read protection status. However, the device
mappable region (eg: devicetree reg property) might be lower than the
device full size which means that the above cycle will result in a data
bus exception. This change fixes it by reading the 'addr_size' during
probe() and also use that as one possible upper limit.

Signed-off-by: Nuno Sá <nuno.sa at analog.com>

 * Fix compilation when CONFIG_CFI_FLASH is not set. Done by redefining
cfi_flash_bank_size() when CONFIG_CFI_FLASH is set (by returning dts
 * Fix another compilation warning by explicitly casting to unsigned
long in cfi_flash_bank_size()
 * Made CI tests pass. Done by going back to the basic v1 patch and
making sure we have proper guards for CONFIG_CFI_FLASH and the proper
casts when needed.
 * Dropped second patch.

Alright, Stefan, I think now it's ready to go. All checks passed for me
in github [1]. Apparently, I needed to go back to version 1 (with proper
fixes) which adds the reg size check without changing any previous
functionality. I cannot say for sure but seems some platforms are
relying on cfi_flash_bank_size() and that cannot be overwritten to
return reg_size. Also dropped the second patch as (I think) it would
only be meaningful to have it if also converting flash_info_t:size which
would be a fairly bigger change...
[1]: https://github.com/u-boot/u-boot/pull/281

 drivers/mtd/cfi_flash.c | 10 +++++++++-
 include/flash.h         |  1 +
 2 files changed, 10 insertions(+), 1 deletion(-)

diff --git a/drivers/mtd/cfi_flash.c b/drivers/mtd/cfi_flash.c
index f378f6fb6139..8ade7949a68e 100644
--- a/drivers/mtd/cfi_flash.c
+++ b/drivers/mtd/cfi_flash.c
@@ -2196,6 +2196,12 @@ ulong flash_get_size(phys_addr_t base, int banknum)
 		/* multiply the size by the number of chips */
 		info->size *= size_ratio;
 		max_size = cfi_flash_bank_size(banknum);
+		if (max_size)
+			max_size = min((unsigned long)info->addr_size, max_size);
+		else
+			max_size = info->addr_size;
 		if (max_size && info->size > max_size) {
 			debug("[truncated from %ldMiB]", info->size >> 20);
 			info->size = max_size;
@@ -2492,15 +2498,17 @@ unsigned long flash_init(void)
 static int cfi_flash_probe(struct udevice *dev)
 	fdt_addr_t addr;
+	fdt_size_t size;
 	int idx;
 	for (idx = 0; idx < CFI_MAX_FLASH_BANKS; idx++) {
-		addr = dev_read_addr_index(dev, idx);
+		addr = dev_read_addr_size_index(dev, idx, &size);
 		if (addr == FDT_ADDR_T_NONE)
 		flash_info[cfi_flash_num_flash_banks].dev = dev;
 		flash_info[cfi_flash_num_flash_banks].base = addr;
+		flash_info[cfi_flash_num_flash_banks].addr_size = size;
 	gd->bd->bi_flashstart = flash_info[0].base;
diff --git a/include/flash.h b/include/flash.h
index 95992fa689bb..3710a2731b76 100644
--- a/include/flash.h
+++ b/include/flash.h
@@ -46,6 +46,7 @@ typedef struct {
 #ifdef CONFIG_CFI_FLASH			/* DM-specific parts */
 	struct udevice *dev;
 	phys_addr_t base;
+	phys_size_t addr_size;
 } flash_info_t;

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