nvmem: sfp: Use regmap

This converts the SFP driver to use regmap. This will allow easily
supporting devices with different endians. We disallow byte-level
access, as regmap_bulk_read doesn't support it (and it's unclear what
the correct result would be when we have an endianness difference).
Signed-off-by: Sean Anderson <sean.anderson@seco.com>
Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
Link: https://lore.kernel.org/r/20220429162701.2222-16-srinivas.kandagatla@linaro.orgSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/nvmem/Kconfig

@@ -304,6 +304,7 @@ config NVMEM_LAYERSCAPE_SFP
 	tristate "Layerscape SFP (Security Fuse Processor) support"
 	depends on ARCH_LAYERSCAPE || COMPILE_TEST
 	depends on HAS_IOMEM
+	select REGMAP_MMIO
 	help
 	  This driver provides support to read the eFuses on Freescale
 	  Layerscape SoC's. For example, the vendor provides a per part

drivers/nvmem/layerscape-sfp.c

@@ -13,15 +13,17 @@
 #include <linux/nvmem-provider.h>
 #include <linux/platform_device.h>
 #include <linux/property.h>
+#include <linux/regmap.h>
 
 #define LAYERSCAPE_SFP_OTP_OFFSET	0x0200
 
 struct layerscape_sfp_priv {
-	void __iomem *base;
+	struct regmap *regmap;
 };
 
 struct layerscape_sfp_data {
 	int size;
+	enum regmap_endian endian;
 };
 
 static int layerscape_sfp_read(void *context, unsigned int offset, void *val,
@@ -29,15 +31,16 @@ static int layerscape_sfp_read(void *context, unsigned int offset, void *val,
 {
 	struct layerscape_sfp_priv *priv = context;
 
-	memcpy_fromio(val, priv->base + LAYERSCAPE_SFP_OTP_OFFSET + offset,
-		      bytes);
-
-	return 0;
+	return regmap_bulk_read(priv->regmap,
+				LAYERSCAPE_SFP_OTP_OFFSET + offset, val,
+				bytes / 4);
 }
 
 static struct nvmem_config layerscape_sfp_nvmem_config = {
 	.name = "fsl-sfp",
 	.reg_read = layerscape_sfp_read,
+	.word_size = 4,
+	.stride = 4,
 };
 
 static int layerscape_sfp_probe(struct platform_device *pdev)
@@ -45,16 +48,26 @@ static int layerscape_sfp_probe(struct platform_device *pdev)
 	const struct layerscape_sfp_data *data;
 	struct layerscape_sfp_priv *priv;
 	struct nvmem_device *nvmem;
+	struct regmap_config config = { 0 };
+	void __iomem *base;
 
 	priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
 	if (!priv)
 		return -ENOMEM;
 
-	priv->base = devm_platform_ioremap_resource(pdev, 0);
-	if (IS_ERR(priv->base))
-		return PTR_ERR(priv->base);
+	base = devm_platform_ioremap_resource(pdev, 0);
+	if (IS_ERR(base))
+		return PTR_ERR(base);
 
 	data = device_get_match_data(&pdev->dev);
+	config.reg_bits = 32;
+	config.reg_stride = 4;
+	config.val_bits = 32;
+	config.val_format_endian = data->endian;
+	config.max_register = LAYERSCAPE_SFP_OTP_OFFSET + data->size - 4;
+	priv->regmap = devm_regmap_init_mmio(&pdev->dev, base, &config);
+	if (IS_ERR(priv->regmap))
+		return PTR_ERR(priv->regmap);
 
 	layerscape_sfp_nvmem_config.size = data->size;
 	layerscape_sfp_nvmem_config.dev = &pdev->dev;
@@ -67,6 +80,7 @@ static int layerscape_sfp_probe(struct platform_device *pdev)
 
 static const struct layerscape_sfp_data ls1028a_data = {
 	.size = 0x88,
+	.endian = REGMAP_ENDIAN_LITTLE,
 };
 
 static const struct of_device_id layerscape_sfp_dt_ids[] = {