[PATCH linux dev-5.3 09/13] mtd: spi-nor: aspeed: Check for disabled segments on the AST2600

[Cédric Le Goater]

The segments can be disabled on the AST2600 (zero register value).
CS0 is open by default but not the other CS. This is closing the
access to the flash device in user mode and forbids scanning. For
multiple CS, we will need firmware or a DT property to reopen the
flash AHB window.

Signed-off-by: Cédric Le Goater <clg at kaod.org>
---
 drivers/mtd/spi-nor/aspeed-smc.c | 15 +++++++++++----
 1 file changed, 11 insertions(+), 4 deletions(-)

diff --git a/drivers/mtd/spi-nor/aspeed-smc.c b/drivers/mtd/spi-nor/aspeed-smc.c
index 6c5ecea21882..ea9b4a157677 100644
--- a/drivers/mtd/spi-nor/aspeed-smc.c
+++ b/drivers/mtd/spi-nor/aspeed-smc.c
@@ -659,8 +659,15 @@ static u32 chip_set_segment(struct aspeed_smc_chip *chip, u32 cs, u32 start,
 	 * size, but take into account the possible overlap with the
 	 * previous segment
 	 */
-	if (!size)
-		size = info->segment_end(controller, seg_oldval) - start;
+	if (!size) {
+		end = info->segment_end(controller, seg_oldval);
+
+		/*
+		 * Check for disabled segment (AST2600).
+		 */
+		if (end != ahb_base_phy)
+			size = end - start;
+	}
 
 	/*
 	 * The segment cannot exceed the maximum window size of the
@@ -689,8 +696,8 @@ static u32 chip_set_segment(struct aspeed_smc_chip *chip, u32 cs, u32 start,
 		size = end - start;
 	}
 
-	dev_info(chip->nor.dev, "CE%d window [ 0x%.8x - 0x%.8x ] %dMB",
-		 cs, start, end, size >> 20);
+	dev_info(chip->nor.dev, "CE%d window [ 0x%.8x - 0x%.8x ] %dMB%s",
+		 cs, start, end, size >> 20, size ? "" : " (disabled)");
 
 	return size;
 }
-- 
2.21.0