eeprom: 93xx46: extend driver to plug into the NVMEM framework

Add a regmap for accessing the EEPROM, and then use that with the
NVMEM framework. Enable backward compatibility in the NVMEM config
structure, so that the 'eeprom' file in sys is provided by the
framework.
Signed-off-by: Andrew Lunn <andrew@lunn.ch>
Acked-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/misc/eeprom/Kconfig

@@ -78,6 +78,8 @@ config EEPROM_93CX6
 config EEPROM_93XX46
 	tristate "Microwire EEPROM 93XX46 support"
 	depends on SPI && SYSFS
+	select REGMAP
+	select NVMEM
 	help
 	  Driver for the microwire EEPROM chipsets 93xx46x. The driver
 	  supports both read and write commands and also the command to

drivers/misc/eeprom/eeprom_93xx46.c

@@ -19,7 +19,8 @@
 #include <linux/of_gpio.h>
 #include <linux/slab.h>
 #include <linux/spi/spi.h>
-#include <linux/sysfs.h>
+#include <linux/nvmem-provider.h>
+#include <linux/regmap.h>
 #include <linux/eeprom_93xx46.h>
 
 #define OP_START	0x4
@@ -41,9 +42,12 @@ static const struct eeprom_93xx46_devtype_data atmel_at93c46d_data = {
 struct eeprom_93xx46_dev {
 	struct spi_device *spi;
 	struct eeprom_93xx46_platform_data *pdata;
-	struct bin_attribute bin;
 	struct mutex lock;
+	struct regmap_config regmap_config;
+	struct nvmem_config nvmem_config;
+	struct nvmem_device *nvmem;
 	int addrlen;
+	int size;
 };
 
 static inline bool has_quirk_single_word_read(struct eeprom_93xx46_dev *edev)
@@ -57,16 +61,17 @@ static inline bool has_quirk_instruction_length(struct eeprom_93xx46_dev *edev)
 }
 
 static ssize_t
-eeprom_93xx46_bin_read(struct file *filp, struct kobject *kobj,
-		       struct bin_attribute *bin_attr,
-		       char *buf, loff_t off, size_t count)
+eeprom_93xx46_read(struct eeprom_93xx46_dev *edev, char *buf,
+		   unsigned off, size_t count)
 {
-	struct eeprom_93xx46_dev *edev;
-	struct device *dev;
 	ssize_t ret = 0;
 
-	dev = kobj_to_dev(kobj);
-	edev = dev_get_drvdata(dev);
+	if (unlikely(off >= edev->size))
+		return 0;
+	if ((off + count) > edev->size)
+		count = edev->size - off;
+	if (unlikely(!count))
+		return count;
 
 	mutex_lock(&edev->lock);
 
@@ -226,16 +231,17 @@ eeprom_93xx46_write_word(struct eeprom_93xx46_dev *edev,
 }
 
 static ssize_t
-eeprom_93xx46_bin_write(struct file *filp, struct kobject *kobj,
-			struct bin_attribute *bin_attr,
-			char *buf, loff_t off, size_t count)
+eeprom_93xx46_write(struct eeprom_93xx46_dev *edev, const char *buf,
+		    loff_t off, size_t count)
 {
-	struct eeprom_93xx46_dev *edev;
-	struct device *dev;
 	int i, ret, step = 1;
 
-	dev = kobj_to_dev(kobj);
-	edev = dev_get_drvdata(dev);
+	if (unlikely(off >= edev->size))
+		return -EFBIG;
+	if ((off + count) > edev->size)
+		count = edev->size - off;
+	if (unlikely(!count))
+		return count;
 
 	/* only write even number of bytes on 16-bit devices */
 	if (edev->addrlen == 6) {
@@ -272,6 +278,49 @@ eeprom_93xx46_bin_write(struct file *filp, struct kobject *kobj,
 	return ret ? : count;
 }
 
+/*
+ * Provide a regmap interface, which is registered with the NVMEM
+ * framework
+*/
+static int eeprom_93xx46_regmap_read(void *context, const void *reg,
+				     size_t reg_size, void *val,
+				     size_t val_size)
+{
+	struct eeprom_93xx46_dev *eeprom_93xx46 = context;
+	off_t offset = *(u32 *)reg;
+	int err;
+
+	err = eeprom_93xx46_read(eeprom_93xx46, val, offset, val_size);
+	if (err)
+		return err;
+	return 0;
+}
+
+static int eeprom_93xx46_regmap_write(void *context, const void *data,
+				      size_t count)
+{
+	struct eeprom_93xx46_dev *eeprom_93xx46 = context;
+	const char *buf;
+	u32 offset;
+	size_t len;
+	int err;
+
+	memcpy(&offset, data, sizeof(offset));
+	buf = (const char *)data + sizeof(offset);
+	len = count - sizeof(offset);
+
+	err = eeprom_93xx46_write(eeprom_93xx46, buf, offset, len);
+	if (err)
+		return err;
+	return 0;
+}
+
+static const struct regmap_bus eeprom_93xx46_regmap_bus = {
+	.read = eeprom_93xx46_regmap_read,
+	.write = eeprom_93xx46_regmap_write,
+	.reg_format_endian_default = REGMAP_ENDIAN_NATIVE,
+};
+
 static int eeprom_93xx46_eral(struct eeprom_93xx46_dev *edev)
 {
 	struct eeprom_93xx46_platform_data *pd = edev->pdata;
@@ -431,6 +480,7 @@ static int eeprom_93xx46_probe(struct spi_device *spi)
 {
 	struct eeprom_93xx46_platform_data *pd;
 	struct eeprom_93xx46_dev *edev;
+	struct regmap *regmap;
 	int err;
 
 	if (spi->dev.of_node) {
@@ -464,19 +514,34 @@ static int eeprom_93xx46_probe(struct spi_device *spi)
 	edev->spi = spi_dev_get(spi);
 	edev->pdata = pd;
 
-	sysfs_bin_attr_init(&edev->bin);
-	edev->bin.attr.name = "eeprom";
-	edev->bin.attr.mode = S_IRUSR;
-	edev->bin.read = eeprom_93xx46_bin_read;
-	edev->bin.size = 128;
-	if (!(pd->flags & EE_READONLY)) {
-		edev->bin.write = eeprom_93xx46_bin_write;
-		edev->bin.attr.mode |= S_IWUSR;
+	edev->size = 128;
+
+	edev->regmap_config.reg_bits = 32;
+	edev->regmap_config.val_bits = 8;
+	edev->regmap_config.reg_stride = 1;
+	edev->regmap_config.max_register = edev->size - 1;
+
+	regmap = devm_regmap_init(&spi->dev, &eeprom_93xx46_regmap_bus, edev,
+				  &edev->regmap_config);
+	if (IS_ERR(regmap)) {
+		dev_err(&spi->dev, "regmap init failed\n");
+		err = PTR_ERR(regmap);
+		goto fail;
 	}
 
-	err = sysfs_create_bin_file(&spi->dev.kobj, &edev->bin);
-	if (err)
+	edev->nvmem_config.name = dev_name(&spi->dev);
+	edev->nvmem_config.dev = &spi->dev;
+	edev->nvmem_config.read_only = pd->flags & EE_READONLY;
+	edev->nvmem_config.root_only = true;
+	edev->nvmem_config.owner = THIS_MODULE;
+	edev->nvmem_config.compat = true;
+	edev->nvmem_config.base_dev = &spi->dev;
+
+	edev->nvmem = nvmem_register(&edev->nvmem_config);
+	if (IS_ERR(edev->nvmem)) {
+		err = PTR_ERR(edev->nvmem);
 		goto fail;
+	}
 
 	dev_info(&spi->dev, "%d-bit eeprom %s\n",
 		(pd->flags & EE_ADDR8) ? 8 : 16,
@@ -498,10 +563,11 @@ static int eeprom_93xx46_remove(struct spi_device *spi)
 {
 	struct eeprom_93xx46_dev *edev = spi_get_drvdata(spi);
 
+	nvmem_unregister(edev->nvmem);
+
 	if (!(edev->pdata->flags & EE_READONLY))
 		device_remove_file(&spi->dev, &dev_attr_erase);
 
-	sysfs_remove_bin_file(&spi->dev.kobj, &edev->bin);
 	kfree(edev);
 	return 0;
 }