[PATCH] mtd: parsers: qcom: deal with partitions names on Netgear WAX218

[Rafał Miłecki]

From: Rafał Miłecki <rafal at milecki.pl>

Netgear WAX218 has two similar partitions: "rootfs" and "rootfs_1". They
both contain device firmware (kernel + rootfs). Bootloader chooses the
one to boot from depending on the "active_fw" variable.

The whole mechanism is used for safe firmware upgrades.

Sadly original bootloader on this device doesn't let know what firmware
it has booted.

To run system reliably we need to know which kernel has been booted and
mount proper rootfs accordingly. This patch registers currently used
partition using the "firmware" name.

It isn't clear how many devices will need this so just check for a
WAX218 compatible string for now.

Signed-off-by: Rafał Miłecki <rafal at milecki.pl>
Cc: Alexandru Gagniuc <mr.nuke.me at gmail.com>
Cc: Christian Marangi <ansuelsmth at gmail.com>
---
 drivers/mtd/parsers/qcomsmempart.c | 92 +++++++++++++++++++++++++++---
 1 file changed, 84 insertions(+), 8 deletions(-)

diff --git a/drivers/mtd/parsers/qcomsmempart.c b/drivers/mtd/parsers/qcomsmempart.c
index 4311b89d8df0..352fb153745c 100644
--- a/drivers/mtd/parsers/qcomsmempart.c
+++ b/drivers/mtd/parsers/qcomsmempart.c
@@ -54,6 +54,69 @@ struct smem_flash_ptable {
 	struct smem_flash_pentry pentry[SMEM_FLASH_PTABLE_MAX_PARTS_V4];
 } __packed __aligned(4);
 
+/**
+ * parse_qcomsmem_get_active_fw - get active firmware index
+ *
+ * Some devices have active and backup/fallback firmwares. This function returns index of the active
+ * one. It's useful for registering MTD partitions using clear names.
+ */
+static int parse_qcomsmem_get_active_fw(struct mtd_info *mtd, struct smem_flash_ptable *ptable)
+{
+	bool found = false;
+	size_t offset;
+	size_t bytes;
+	size_t size;
+	char *buf;
+	char *var;
+	int err;
+	int i;
+
+	if (!of_machine_is_compatible("netgear,wax218"))
+		return -EOPNOTSUPP;
+
+	/* Find partition with environment data */
+
+	for (i = 0; i < le32_to_cpu(ptable->numparts); i++) {
+		struct smem_flash_pentry *pentry = &ptable->pentry[i];
+
+		if (!strcmp(pentry->name, "0:APPSBLENV")) {
+			offset = le32_to_cpu(pentry->offset) * mtd->erasesize;
+			size = le32_to_cpu(pentry->length) * mtd->erasesize;
+			found = true;
+			break;
+		}
+	}
+	if (!found)
+		return -ENOENT;
+
+	/* Read it */
+
+	buf = kcalloc(1, size, GFP_KERNEL);
+	if (!buf)
+		return -ENOMEM;
+
+	err = mtd_read(mtd, offset, size, &bytes, buf);
+	if ((err && !mtd_is_bitflip(err)) || bytes != size) {
+		pr_err("Failed to read environment\n");
+		return -EIO;
+	}
+
+	/* Find & parse entry with active firmware index */
+
+	for (var = buf + 4; var < buf + size && *var; var += strlen(var) + 1) {
+		const char *prefix = "active_fw=";
+		unsigned long idx;
+
+		if (strstarts(var, prefix)) {
+			err = kstrtol(var + strlen(prefix), 0, &idx);
+
+			return err ? err : idx;
+		}
+	}
+
+	return -ENOENT;
+}
+
 static int parse_qcomsmem_part(struct mtd_info *mtd,
 			       const struct mtd_partition **pparts,
 			       struct mtd_part_parser_data *data)
@@ -64,6 +127,8 @@ static int parse_qcomsmem_part(struct mtd_info *mtd,
 	struct smem_flash_ptable *ptable;
 	struct mtd_partition *parts;
 	char *name, *c;
+	int active_fw;
+	int fw_idx;
 
 	if (IS_ENABLED(CONFIG_MTD_SPI_NOR_USE_4K_SECTORS)
 			&& mtd->type == MTD_NORFLASH) {
@@ -123,24 +188,35 @@ static int parse_qcomsmem_part(struct mtd_info *mtd,
 			numparts++;
 	}
 
+	active_fw = parse_qcomsmem_get_active_fw(mtd, ptable);
+
 	parts = kcalloc(numparts, sizeof(*parts), GFP_KERNEL);
 	if (!parts)
 		return -ENOMEM;
 
+	fw_idx = -1;
 	for (i = 0, j = 0; i < tmpparts; i++) {
 		pentry = &ptable->pentry[i];
 		if (pentry->name[0] == '\0')
 			continue;
 
-		name = kstrdup(pentry->name, GFP_KERNEL);
-		if (!name) {
-			ret = -ENOMEM;
-			goto out_free_parts;
-		}
+		if (active_fw >= 0 && strstarts(pentry->name, "rootfs")) {
+			name = kstrdup(++fw_idx == active_fw ? "firmware" : "backup", GFP_KERNEL);
+			if (!name) {
+				ret = -ENOMEM;
+				goto out_free_parts;
+			}
+		} else {
+			name = kstrdup(pentry->name, GFP_KERNEL);
+			if (!name) {
+				ret = -ENOMEM;
+				goto out_free_parts;
+			}
 
-		/* Convert name to lower case */
-		for (c = name; *c != '\0'; c++)
-			*c = tolower(*c);
+			/* Convert name to lower case */
+			for (c = name; *c != '\0'; c++)
+				*c = tolower(*c);
+		}
 
 		parts[j].name = name;
 		parts[j].offset = le32_to_cpu(pentry->offset) * mtd->erasesize;
-- 
2.34.1