[PATCH v3] mtd: spi-nor: Add support for Cypress cy15x104q

[Sascha Hauer <s.hauer@xxxxxxxxxxxxxx>]

The Cypress cy15b104q and cy15v104q are 4Mbit serial SPI F-RAM devices.
Add support for them to the spi-nor driver.

The actual Device ID of this chip is 7f 7f 7f 7f 7f 7f c2 2c 04. That is
six times the continuation code 7f followed by c2 for Ramtron.
Unfortunately the chip sends the Device ID in reversed order, so the
continuation code is not at the beginning, but instead at the end. Even
more unfortunate is that when reading further the chip sends more 7f
codes which means we are not even able to count the continuation codes.
We can only hope that this reversed Device ID will never match any other
devices ID.

Signed-off-by: Sascha Hauer <s.hauer@xxxxxxxxxxxxxx>
---

Changes since v2:
- Add explanation of the reversed order of the Device ID to the commit message
Changes since v1:
- Instead of specifying 1024 sectors with a sector size of 512 specify
  512 * 1024 sectos with a sector size of 1. The device has no idea of
  sectors and is not erasable, so a sector size of 1 seems to better
  reflect reality.

 drivers/mtd/spi-nor/spansion.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/mtd/spi-nor/spansion.c b/drivers/mtd/spi-nor/spansion.c
index 6756202ace4b..3e8ac602e36b 100644
--- a/drivers/mtd/spi-nor/spansion.c
+++ b/drivers/mtd/spi-nor/spansion.c
@@ -70,6 +70,7 @@ static const struct flash_info spansion_parts[] = {
 	{ "s25fl256l",  INFO(0x016019,      0,  64 * 1024, 512,
 			     SECT_4K | SPI_NOR_DUAL_READ | SPI_NOR_QUAD_READ |
 			     SPI_NOR_4B_OPCODES) },
+	{ "cy15x104q",  INFO6(0x042cc2, 0x7f7f7f, 512 * 1024, 1, SPI_NOR_NO_ERASE) },
 };
 
 static void spansion_post_sfdp_fixups(struct spi_nor *nor)
-- 
2.26.1


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