[PATCH 2/3] mtd: spi-nor: use rdid-dummy-ncycles DT property

[Takahiro Kuwano]

There are infineon flashes [1] that require 8 dummy cycles for the
1-1-1 Read ID command. Since the command is not covered by JESD216
or any other standard, get the number of dummy cycles from DT and use
them to correctly identify the flash.

Link: https://www.infineon.com/dgdl/Infineon-CYRS17B512_512_MB_64_MB_SERIAL_NOR_FLASH_SPI_QSPI_3-DataSheet-v07_00-EN.pdf?fileId=8ac78c8c8fc2dd9c01900eee733d45f3 [1]
Signed-off-by: Takahiro Kuwano <Takahiro.Kuwano@xxxxxxxxxxxx>
---
 drivers/mtd/spi-nor/core.c | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/drivers/mtd/spi-nor/core.c b/drivers/mtd/spi-nor/core.c
index 19eb98bd68210f41acd716635c02a8936678a385..6452ae6eecee3325b52cdcc2cc9703355951e0db 100644
--- a/drivers/mtd/spi-nor/core.c
+++ b/drivers/mtd/spi-nor/core.c
@@ -7,6 +7,7 @@
  * Copyright (C) 2014, Freescale Semiconductor, Inc.
  */
 
+#include <linux/bits.h>
 #include <linux/err.h>
 #include <linux/errno.h>
 #include <linux/delay.h>
@@ -16,6 +17,7 @@
 #include <linux/mtd/mtd.h>
 #include <linux/mtd/spi-nor.h>
 #include <linux/mutex.h>
+#include <linux/of.h>
 #include <linux/of_platform.h>
 #include <linux/regulator/consumer.h>
 #include <linux/sched/task_stack.h>
@@ -2011,9 +2013,14 @@ static const struct flash_info *spi_nor_detect(struct spi_nor *nor)
 {
 	const struct flash_info *info;
 	u8 *id = nor->bouncebuf;
+	u32 ndummy = 0;
 	int ret;
 
-	ret = spi_nor_read_id(nor, 0, 0, id, nor->reg_proto);
+	if (!of_property_read_u32(nor->dev->of_node, "rdid-dummy-ncycles",
+				  &ndummy))
+		ndummy /= BITS_PER_BYTE;
+
+	ret = spi_nor_read_id(nor, 0, ndummy, id, nor->reg_proto);
 	if (ret) {
 		dev_dbg(nor->dev, "error %d reading JEDEC ID\n", ret);
 		return ERR_PTR(ret);

-- 
2.34.1