[PATCH u-boot-dm + u-boot-spi v3 10/11] mtd: compare also with OF path and device name in get_mtd_device_nm()

[Marek Behún]

The get_mtd_device_nm() function (code imported from Linux) simply
iterates all registered MTD devices and compares the given name with
all MTDs' names.

With SPI_FLASH_MTD enabled U-Boot registers a SPI-NOR as a MTD device
with name identical to the SPI flash chip name (from SPI ID table). Thus
for a board with multiple same SPI-NORs it registers multiple MTDs, but
all with the same name (such as "s25fl164k"). We do not want to change
this behaviour, since such a change could break existing boot scripts,
which can rely on a hardcoded name.

In order to allow somehow to uniqely select a MTD device, change
get_mtd_device_nm() function as such:
- if first character of name is '/', interpret it as OF path
- otherwise compare the name with MTDs name and MTDs device name.

In the following example a board has two "s25fl164k" SPI-NORs. They both
have name "s25fl164k", thus cannot be uniquely selected via this name.
With this change, the user can select the second SPI-NOR either with
"spi-nor at 1" or "/soc/spi at 10600/spi-nor at 1".

Example:
  => mtd list
  List of MTD devices:
  * s25fl164k
    - device: spi-nor at 0
    - parent: spi at 10600
    - driver: jedec_spi_nor
    - path: /soc/spi at 10600/spi-nor at 0
    - type: NOR flash
    - block size: 0x1000 bytes
    - min I/O: 0x1 bytes
    - 0x000000000000-0x000000800000 : "s25fl164k"
  * s25fl164k
    - device: spi-nor at 1
    - parent: spi at 10600
    - driver: jedec_spi_nor
    - path: /soc/spi at 10600/spi-nor at 1
    - type: NOR flash
    - block size: 0x1000 bytes
    - min I/O: 0x1 bytes
    - 0x000000000000-0x000000800000 : "s25fl164k"

This change adds code that depends on CONFIG_DM. Although CONFIG_DM
is compulsory since v2020.01, there are still some boards (for example
tqma6s_wru4_mmc_defconfig) that don't enable it. Therefore the code
guards this parts by #ifdefs.

Signed-off-by: Marek Behún <marek.behun at nic.cz>
Cc: Jagan Teki <jagan at amarulasolutions.com>
Cc: Priyanka Jain <priyanka.jain at nxp.com>
Cc: Simon Glass <sjg at chromium.org>
Cc: Heiko Schocher <hs at denx.de>
Cc: Jagan Teki <jagan at amarulasolutions.com>
Cc: Patrick Delaunay <patrick.delaunay at st.com>
Cc: Patrice CHOTARD <patrice.chotard at foss.st.com>
Cc: Miquel Raynal <miquel.raynal at bootlin.com>
---
 drivers/mtd/mtdcore.c | 29 +++++++++++++++++++++++++++++
 1 file changed, 29 insertions(+)

diff --git a/drivers/mtd/mtdcore.c b/drivers/mtd/mtdcore.c
index 0d1f94c6cb..7c894b2e41 100644
--- a/drivers/mtd/mtdcore.c
+++ b/drivers/mtd/mtdcore.c
@@ -780,13 +780,42 @@ struct mtd_info *get_mtd_device_nm(const char *name)
 {
 	int err = -ENODEV;
 	struct mtd_info *mtd = NULL, *other;
+#ifdef CONFIG_DM
+	struct udevice *dev = NULL;
+#endif
+
+#ifdef CONFIG_DM
+	/*
+	 * If the first character of mtd name is '/', interpret it as OF path.
+	 * Otherwise try comparing by mtd->name and mtd->dev->name.
+	 */
+	if (*name == '/') {
+		err = device_get_global_by_ofnode(ofnode_path(name), &dev);
+		if (err)
+			return ERR_PTR(err);
+	}
+#endif
 
 	mutex_lock(&mtd_table_mutex);
 
 	mtd_for_each_device(other) {
+#ifdef CONFIG_DM
+		if ((dev && !mtd_is_partition(other) && other->dev == dev) ||
+		    !strcmp(name, other->name) ||
+		    (!mtd_is_partition(other) && other->dev &&
+		     !strcmp(name, other->dev->name))) {
+#else
 		if (!strcmp(name, other->name)) {
+#endif
+#ifdef __UBOOT__
+			if (mtd)
+				printf("\nWarning: MTD name \"%s\" is not unique!\n\n",
+				       name);
+			mtd = other;
+#else /* !__UBOOT__ */
 			mtd = other;
 			break;
+#endif /* !__UBOOT__ */
 		}
 	}
 
-- 
2.26.2