nvmem: brcm_nvram: parse NVRAM content into NVMEM cells

NVRAM consist of header and NUL separated key-value pairs. Parse it and
create NVMEM cell for every key-value entry.
Signed-off-by: NRafał Miłecki <rafal@milecki.pl>
Signed-off-by: NSrinivas Kandagatla <srinivas.kandagatla@linaro.org>
Link: https://lore.kernel.org/r/20220225175822.8293-3-srinivas.kandagatla@linaro.orgSigned-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/nvmem/brcm_nvram.c

@@ -6,12 +6,26 @@
 #include <linux/io.h>
 #include <linux/mod_devicetable.h>
 #include <linux/module.h>
+#include <linux/nvmem-consumer.h>
 #include <linux/nvmem-provider.h>
 #include <linux/platform_device.h>
+#include <linux/slab.h>
+
+#define NVRAM_MAGIC			"FLSH"
 
 struct brcm_nvram {
 	struct device *dev;
 	void __iomem *base;
+	struct nvmem_cell_info *cells;
+	int ncells;
+};
+
+struct brcm_nvram_header {
+	char magic[4];
+	__le32 len;
+	__le32 crc_ver_init;	/* 0:7 crc, 8:15 ver, 16:31 sdram_init */
+	__le32 config_refresh;	/* 0:15 sdram_config, 16:31 sdram_refresh */
+	__le32 config_ncdl;	/* ncdl values for memc */
 };
 
 static int brcm_nvram_read(void *context, unsigned int offset, void *val,
@@ -26,6 +40,75 @@ static int brcm_nvram_read(void *context, unsigned int offset, void *val,
 	return 0;
 }
 
+static int brcm_nvram_add_cells(struct brcm_nvram *priv, uint8_t *data,
+				size_t len)
+{
+	struct device *dev = priv->dev;
+	char *var, *value, *eq;
+	int idx;
+
+	priv->ncells = 0;
+	for (var = data + sizeof(struct brcm_nvram_header);
+	     var < (char *)data + len && *var;
+	     var += strlen(var) + 1) {
+		priv->ncells++;
+	}
+
+	priv->cells = devm_kcalloc(dev, priv->ncells, sizeof(*priv->cells), GFP_KERNEL);
+	if (!priv->cells)
+		return -ENOMEM;
+
+	for (var = data + sizeof(struct brcm_nvram_header), idx = 0;
+	     var < (char *)data + len && *var;
+	     var = value + strlen(value) + 1, idx++) {
+		eq = strchr(var, '=');
+		if (!eq)
+			break;
+		*eq = '\0';
+		value = eq + 1;
+
+		priv->cells[idx].name = devm_kstrdup(dev, var, GFP_KERNEL);
+		if (!priv->cells[idx].name)
+			return -ENOMEM;
+		priv->cells[idx].offset = value - (char *)data;
+		priv->cells[idx].bytes = strlen(value);
+	}
+
+	return 0;
+}
+
+static int brcm_nvram_parse(struct brcm_nvram *priv)
+{
+	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)) {
+		dev_err(dev, "Invalid NVRAM magic\n");
+		return -EINVAL;
+	}
+
+	len = le32_to_cpu(header.len);
+
+	data = kcalloc(1, len, GFP_KERNEL);
+	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;
+	}
+
+	kfree(data);
+
+	return 0;
+}
+
 static int brcm_nvram_probe(struct platform_device *pdev)
 {
 	struct nvmem_config config = {
@@ -35,6 +118,7 @@ static int brcm_nvram_probe(struct platform_device *pdev)
 	struct device *dev = &pdev->dev;
 	struct resource *res;
 	struct brcm_nvram *priv;
+	int err;
 
 	priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
 	if (!priv)
@@ -46,7 +130,13 @@ static int brcm_nvram_probe(struct platform_device *pdev)
 	if (IS_ERR(priv->base))
 		return PTR_ERR(priv->base);
 
+	err = brcm_nvram_parse(priv);
+	if (err)
+		return err;
+
 	config.dev = dev;
+	config.cells = priv->cells;
+	config.ncells = priv->ncells;
 	config.priv = priv;
 	config.size = resource_size(res);