kernel: backport support for m25p80 compatible="jedec,spi-nor" in DT

Signed-off-by: Felix Fietkau <nbd@openwrt.org>

SVN-Revision: 47716

target/linux/generic/patches-3.18/044-backport-m25p80-jedec-probe.patch

+--- a/drivers/mtd/devices/m25p80.c
++++ b/drivers/mtd/devices/m25p80.c
+@@ -310,11 +310,21 @@ static const struct spi_device_id m25p_i
+ };
+ MODULE_DEVICE_TABLE(spi, m25p_ids);
+ 
++static const struct of_device_id m25p_of_table[] = {
++	/*
++	 * Generic compatibility for SPI NOR that can be identified by the
++	 * JEDEC READ ID opcode (0x9F). Use this, if possible.
++	 */
++	{ .compatible = "jedec,spi-nor" },
++	{}
++};
++MODULE_DEVICE_TABLE(of, m25p_of_table);
+ 
+ static struct spi_driver m25p80_driver = {
+ 	.driver = {
+ 		.name	= "m25p80",
+ 		.owner	= THIS_MODULE,
++		.of_match_table = m25p_of_table,
+ 	},
+ 	.id_table	= m25p_ids,
+ 	.probe	= m25p_probe,
+--- a/drivers/mtd/spi-nor/spi-nor.c
++++ b/drivers/mtd/spi-nor/spi-nor.c
+@@ -927,8 +927,11 @@ int spi_nor_scan(struct spi_nor *nor, co
+ 	if (ret)
+ 		return ret;
+ 
+-	id = spi_nor_match_id(name);
++	if (name)
++		id = spi_nor_match_id(name);
+ 	if (!id)
++		id = nor->read_id(nor);
++	if (IS_ERR_OR_NULL(id))
+ 		return -ENOENT;
+ 
+ 	info = (void *)id->driver_data;