--- /dev/null
+From: =?UTF-8?q?Rafa=C5=82=20Mi=C5=82ecki?= <rafal@milecki.pl>
+Date: Thu, 14 Sep 2023 07:59:09 +0200
+Subject: [PATCH] nvmem: brcm_nvram: store a copy of NVRAM content
+MIME-Version: 1.0
+Content-Type: text/plain; charset=UTF-8
+Content-Transfer-Encoding: 8bit
+
+This driver uses MMIO access for reading NVRAM from a flash device.
+Underneath there is a flash controller that reads data and provides
+mapping window.
+
+Using MMIO interface affects controller configuration and may break real
+controller driver. It was reported by multiple users of devices with
+NVRAM stored on NAND.
+
+Modify driver to read & cache NVRAM content during init and use that
+copy to provide NVMEM data when requested. On NAND flashes due to their
+alignment NVRAM partitions can be quite big (1 MiB and more) while
+actual NVRAM content stays quite small (usually 16 to 32 KiB). To avoid
+allocating so much memory check for actual data length.
+
+Link: https://lore.kernel.org/linux-mtd/CACna6rwf3_9QVjYcM+847biTX=K0EoWXuXcSMkJO1Vy_5vmVqA@mail.gmail.com/
+Fixes: 3fef9ed0627a ("nvmem: brcm_nvram: new driver exposing Broadcom's NVRAM")
+Cc: Arınç ÜNAL <arinc.unal@arinc9.com>
+Cc: Florian Fainelli <florian.fainelli@broadcom.com>
+Cc: Scott Branden <scott.branden@broadcom.com>
+Signed-off-by: Rafał Miłecki <rafal@milecki.pl>
+Acked-by: Arınç ÜNAL <arinc.unal@arinc9.com>
+---
+ drivers/nvmem/brcm_nvram.c | 134 ++++++++++++++++++++++++++-----------
+ 1 file changed, 94 insertions(+), 40 deletions(-)
+
+--- a/drivers/nvmem/brcm_nvram.c
++++ b/drivers/nvmem/brcm_nvram.c
+@@ -17,9 +17,23 @@
+
+ #define NVRAM_MAGIC "FLSH"
+
++/**
++ * struct brcm_nvram - driver state internal struct
++ *
++ * @dev: NVMEM device pointer
++ * @nvmem_size: Size of the whole space available for NVRAM
++ * @data: NVRAM data copy stored to avoid poking underlaying flash controller
++ * @data_len: NVRAM data size
++ * @padding_byte: Padding value used to fill remaining space
++ * @cells: Array of discovered NVMEM cells
++ * @ncells: Number of elements in cells
++ */
+ struct brcm_nvram {
+ struct device *dev;
+- void __iomem *base;
++ size_t nvmem_size;
++ uint8_t *data;
++ size_t data_len;
++ uint8_t padding_byte;
+ struct nvmem_cell_info *cells;
+ int ncells;
+ };
+@@ -36,10 +50,47 @@ static int brcm_nvram_read(void *context
+ size_t bytes)
+ {
+ struct brcm_nvram *priv = context;
+- u8 *dst = val;
++ size_t to_copy;
++
++ if (offset + bytes > priv->data_len)
++ to_copy = max_t(ssize_t, (ssize_t)priv->data_len - offset, 0);
++ else
++ to_copy = bytes;
++
++ memcpy(val, priv->data + offset, to_copy);
++
++ memset((uint8_t *)val + to_copy, priv->padding_byte, bytes - to_copy);
++
++ return 0;
++}
++
++static int brcm_nvram_copy_data(struct brcm_nvram *priv, struct platform_device *pdev)
++{
++ struct resource *res;
++ void __iomem *base;
++
++ base = devm_platform_get_and_ioremap_resource(pdev, 0, &res);
++ if (IS_ERR(base))
++ return PTR_ERR(base);
++
++ priv->nvmem_size = resource_size(res);
++
++ priv->padding_byte = readb(base + priv->nvmem_size - 1);
++ for (priv->data_len = priv->nvmem_size;
++ priv->data_len;
++ priv->data_len--) {
++ if (readb(base + priv->data_len - 1) != priv->padding_byte)
++ break;
++ }
++ WARN(priv->data_len > SZ_128K, "Unexpected (big) NVRAM size: %zu B\n", priv->data_len);
+
+- while (bytes--)
+- *dst++ = readb(priv->base + offset++);
++ priv->data = devm_kzalloc(priv->dev, priv->data_len, GFP_KERNEL);
++ if (!priv->data)
++ return -ENOMEM;
++
++ memcpy_fromio(priv->data, base, priv->data_len);
++
++ bcm47xx_nvram_init_from_iomem(base, priv->data_len);
+
+ return 0;
+ }
+@@ -67,8 +118,13 @@ static int brcm_nvram_add_cells(struct b
+ size_t len)
+ {
+ struct device *dev = priv->dev;
+- char *var, *value, *eq;
++ char *var, *value;
++ uint8_t tmp;
+ int idx;
++ int err = 0;
++
++ tmp = priv->data[len - 1];
++ priv->data[len - 1] = '\0';
+
+ priv->ncells = 0;
+ for (var = data + sizeof(struct brcm_nvram_header);
+@@ -78,67 +134,68 @@ static int brcm_nvram_add_cells(struct b
+ }
+
+ priv->cells = devm_kcalloc(dev, priv->ncells, sizeof(*priv->cells), GFP_KERNEL);
+- if (!priv->cells)
+- return -ENOMEM;
++ if (!priv->cells) {
++ err = -ENOMEM;
++ goto out;
++ }
+
+ for (var = data + sizeof(struct brcm_nvram_header), idx = 0;
+ var < (char *)data + len && *var;
+ var = value + strlen(value) + 1, idx++) {
++ char *eq, *name;
++
+ eq = strchr(var, '=');
+ if (!eq)
+ break;
+ *eq = '\0';
++ name = devm_kstrdup(dev, var, GFP_KERNEL);
++ *eq = '=';
++ if (!name) {
++ err = -ENOMEM;
++ goto out;
++ }
+ value = eq + 1;
+
+- priv->cells[idx].name = devm_kstrdup(dev, var, GFP_KERNEL);
+- if (!priv->cells[idx].name)
+- return -ENOMEM;
++ priv->cells[idx].name = name;
+ priv->cells[idx].offset = value - (char *)data;
+ priv->cells[idx].bytes = strlen(value);
+ priv->cells[idx].np = of_get_child_by_name(dev->of_node, priv->cells[idx].name);
+- if (!strcmp(var, "et0macaddr") ||
+- !strcmp(var, "et1macaddr") ||
+- !strcmp(var, "et2macaddr")) {
++ if (!strcmp(name, "et0macaddr") ||
++ !strcmp(name, "et1macaddr") ||
++ !strcmp(name, "et2macaddr")) {
+ priv->cells[idx].raw_len = strlen(value);
+ priv->cells[idx].bytes = ETH_ALEN;
+ priv->cells[idx].read_post_process = brcm_nvram_read_post_process_macaddr;
+ }
+ }
+
+- return 0;
++out:
++ priv->data[len - 1] = tmp;
++ return err;
+ }
+
+ static int brcm_nvram_parse(struct brcm_nvram *priv)
+ {
++ struct brcm_nvram_header *header = (struct brcm_nvram_header *)priv->data;
+ struct device *dev = priv->dev;
+- struct brcm_nvram_header header;
+- uint8_t *data;
+ size_t len;
+ int err;
+
+- memcpy_fromio(&header, priv->base, sizeof(header));
+-
+- if (memcmp(header.magic, NVRAM_MAGIC, 4)) {
++ if (memcmp(header->magic, NVRAM_MAGIC, 4)) {
+ dev_err(dev, "Invalid NVRAM magic\n");
+ return -EINVAL;
+ }
+
+- len = le32_to_cpu(header.len);
+-
+- data = kzalloc(len, GFP_KERNEL);
+- if (!data)
+- return -ENOMEM;
+-
+- memcpy_fromio(data, priv->base, len);
+- data[len - 1] = '\0';
+-
+- err = brcm_nvram_add_cells(priv, data, len);
+- if (err) {
+- dev_err(dev, "Failed to add cells: %d\n", err);
+- return err;
++ len = le32_to_cpu(header->len);
++ if (len > priv->nvmem_size) {
++ dev_err(dev, "NVRAM length (%zd) exceeds mapped size (%zd)\n", len,
++ priv->nvmem_size);
++ return -EINVAL;
+ }
+
+- kfree(data);
++ err = brcm_nvram_add_cells(priv, priv->data, len);
++ if (err)
++ dev_err(dev, "Failed to add cells: %d\n", err);
+
+ return 0;
+ }
+@@ -150,7 +207,6 @@ static int brcm_nvram_probe(struct platf
+ .reg_read = brcm_nvram_read,
+ };
+ struct device *dev = &pdev->dev;
+- struct resource *res;
+ struct brcm_nvram *priv;
+ int err;
+
+@@ -159,21 +215,19 @@ static int brcm_nvram_probe(struct platf
+ return -ENOMEM;
+ priv->dev = dev;
+
+- priv->base = devm_platform_get_and_ioremap_resource(pdev, 0, &res);
+- if (IS_ERR(priv->base))
+- return PTR_ERR(priv->base);
++ err = brcm_nvram_copy_data(priv, pdev);
++ if (err)
++ return err;
+
+ err = brcm_nvram_parse(priv);
+ if (err)
+ return err;
+
+- bcm47xx_nvram_init_from_iomem(priv->base, resource_size(res));
+-
+ config.dev = dev;
+ config.cells = priv->cells;
+ config.ncells = priv->ncells;
+ config.priv = priv;
+- config.size = resource_size(res);
++ config.size = priv->nvmem_size;
+
+ return PTR_ERR_OR_ZERO(devm_nvmem_register(dev, &config));
+ }
projects / openwrt / openwrt.git / commitdiff