Merge branch 'for-next/nvmem'

10 files changed, 1064 insertions, 0 deletions

diff --git a/drivers/Kconfig b/drivers/Kconfig
index 44159f83d3..ced8f3d0f8 100644
--- a/drivers/Kconfig
+++ b/drivers/Kconfig
@@ -27,6 +27,7 @@ source "drivers/dma/Kconfig"
 source "drivers/gpio/Kconfig"
 source "drivers/w1/Kconfig"
 source "drivers/pinctrl/Kconfig"
+source "drivers/nvmem/Kconfig"
 source "drivers/bus/Kconfig"
 source "drivers/regulator/Kconfig"
 source "drivers/reset/Kconfig"
diff --git a/drivers/Makefile b/drivers/Makefile
index d46cc28869..4ce781b63f 100644
--- a/drivers/Makefile
+++ b/drivers/Makefile
@@ -19,6 +19,7 @@ obj-y	+= eeprom/
 obj-$(CONFIG_PWM) += pwm/
 obj-y	+= input/
 obj-y	+= misc/
+obj-$(CONFIG_NVMEM) += nvmem/
 obj-y	+= dma/
 obj-y  += watchdog/
 obj-y	+= gpio/
diff --git a/drivers/nvmem/Kconfig b/drivers/nvmem/Kconfig
new file mode 100644
index 0000000000..d801cc25af
--- /dev/null
+++ b/drivers/nvmem/Kconfig
@@ -0,0 +1,18 @@
+menuconfig NVMEM
+	bool "NVMEM Support"
+	help
+	  Support for NVMEM(Non Volatile Memory) devices like EEPROM, EFUSES...
+
+	  This framework is designed to provide a generic interface to NVMEM
+
+	  If unsure, say no.
+
+if NVMEM
+
+config NVMEM_SNVS_LPGPR
+	tristate "Freescale SNVS LPGPR support"
+	select MFD_SYSCON
+	help
+	  If you say yes here you get NVMEM support for the Freescale SNVS
+	  Low Power Generic Purpose Register (LPGPR).
+endif
diff --git a/drivers/nvmem/Makefile b/drivers/nvmem/Makefile
new file mode 100644
index 0000000000..32522e9fbf
--- /dev/null
+++ b/drivers/nvmem/Makefile
@@ -0,0 +1,10 @@
+#
+# Makefile for nvmem drivers.
+#
+
+obj-$(CONFIG_NVMEM)		+= nvmem_core.o
+nvmem_core-y			:= core.o
+
+# Devices
+obj-$(CONFIG_NVMEM_SNVS_LPGPR)	+= nvmem_snvs_lpgpr.o
+nvmem_snvs_lpgpr-y		:= snvs_lpgpr.o
diff --git a/drivers/nvmem/core.c b/drivers/nvmem/core.c
new file mode 100644
index 0000000000..4e50a8843f
--- /dev/null
+++ b/drivers/nvmem/core.c
@@ -0,0 +1,764 @@
+/*
+ * nvmem framework core.
+ *
+ * Copyright (C) 2015 Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
+ * Copyright (C) 2013 Maxime Ripard <maxime.ripard@free-electrons.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 and
+ * only version 2 as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+#include <common.h>
+#include <libbb.h>
+#include <malloc.h>
+#include <of.h>
+#include <linux/nvmem-consumer.h>
+#include <linux/nvmem-provider.h>
+
+struct nvmem_device {
+	const char		*name;
+	struct device_d		dev;
+	const struct nvmem_bus	*bus;
+	struct list_head	node;
+	int			stride;
+	int			word_size;
+	int			ncells;
+	int			users;
+	size_t			size;
+	bool			read_only;
+	struct cdev		cdev;
+};
+
+struct nvmem_cell {
+	const char		*name;
+	int			offset;
+	int			bytes;
+	int			bit_offset;
+	int			nbits;
+	struct nvmem_device	*nvmem;
+	struct list_head	node;
+};
+
+static LIST_HEAD(nvmem_cells);
+static LIST_HEAD(nvmem_devs);
+
+int nvmem_device_read(struct nvmem_device *nvmem, unsigned int offset,
+		      size_t bytes, void *buf);
+int nvmem_device_write(struct nvmem_device *nvmem, unsigned int offset,
+		       size_t bytes, const void *buf);
+
+
+static ssize_t nvmem_cdev_read(struct cdev *cdev, void *buf, size_t count,
+			       loff_t offset, unsigned long flags)
+{
+	struct nvmem_device *nvmem = container_of(cdev, struct nvmem_device, cdev);
+	ssize_t retlen;
+
+	dev_dbg(cdev->dev, "read ofs: 0x%08llx count: 0x%08zx\n",
+		offset, count);
+
+	retlen = nvmem_device_read(nvmem, offset, count, buf);
+
+	return retlen;
+}
+
+static ssize_t nvmem_cdev_write(struct cdev *cdev, const void *buf, size_t count,
+				loff_t offset, unsigned long flags)
+{
+	struct nvmem_device *nvmem = container_of(cdev, struct nvmem_device, cdev);
+	ssize_t retlen;
+
+	dev_dbg(cdev->dev, "write ofs: 0x%08llx count: 0x%08zx\n",
+		offset, count);
+
+	retlen = nvmem_device_write(nvmem, offset, count, buf);
+
+	return retlen;
+}
+
+static struct file_operations nvmem_chrdev_ops = {
+	.read  = nvmem_cdev_read,
+	.write  = nvmem_cdev_write,
+	.lseek = dev_lseek_default,
+};
+
+static int nvmem_register_cdev(struct nvmem_device *nvmem)
+{
+	struct device_d *dev = &nvmem->dev;
+	const char *alias;
+	char *devname;
+	int err;
+
+	alias = of_alias_get(dev->device_node);
+	if (alias) {
+		devname = xstrdup(alias);
+	} else {
+		err = cdev_find_free_index("nvmem");
+		if (err < 0) {
+			dev_err(dev, "no index found to name device\n");
+			return err;
+		}
+		devname = xasprintf("nvmem%d", err);
+	}
+
+	nvmem->cdev.name = devname;
+	nvmem->cdev.flags = DEVFS_IS_CHARACTER_DEV;
+	nvmem->cdev.ops = &nvmem_chrdev_ops;
+	nvmem->cdev.dev = &nvmem->dev;
+	nvmem->cdev.size = nvmem->size;
+
+	return devfs_create(&nvmem->cdev);
+}
+
+static struct nvmem_device *of_nvmem_find(struct device_node *nvmem_np)
+{
+	struct nvmem_device *dev;
+
+	if (!nvmem_np)
+		return NULL;
+
+	list_for_each_entry(dev, &nvmem_devs, node)
+		if (dev->dev.device_node->name && !strcmp(dev->dev.device_node->name, nvmem_np->name))
+			return dev;
+
+	return NULL;
+}
+
+static struct nvmem_cell *nvmem_find_cell(const char *cell_id)
+{
+	struct nvmem_cell *p;
+
+	list_for_each_entry(p, &nvmem_cells, node)
+		if (p && !strcmp(p->name, cell_id))
+			return p;
+
+	return NULL;
+}
+
+static void nvmem_cell_drop(struct nvmem_cell *cell)
+{
+	list_del(&cell->node);
+	kfree(cell);
+}
+
+static void nvmem_cell_add(struct nvmem_cell *cell)
+{
+	list_add_tail(&cell->node, &nvmem_cells);
+}
+
+static int nvmem_cell_info_to_nvmem_cell(struct nvmem_device *nvmem,
+				   const struct nvmem_cell_info *info,
+				   struct nvmem_cell *cell)
+{
+	cell->nvmem = nvmem;
+	cell->offset = info->offset;
+	cell->bytes = info->bytes;
+	cell->name = info->name;
+
+	cell->bit_offset = info->bit_offset;
+	cell->nbits = info->nbits;
+
+	if (cell->nbits)
+		cell->bytes = DIV_ROUND_UP(cell->nbits + cell->bit_offset,
+					   BITS_PER_BYTE);
+
+	if (!IS_ALIGNED(cell->offset, nvmem->stride)) {
+		dev_err(&nvmem->dev,
+			"cell %s unaligned to nvmem stride %d\n",
+			cell->name, nvmem->stride);
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+/**
+ * nvmem_register() - Register a nvmem device for given nvmem_config.
+ *
+ * @config: nvmem device configuration with which nvmem device is created.
+ *
+ * Return: Will be an ERR_PTR() on error or a valid pointer to nvmem_device
+ * on success.
+ */
+
+struct nvmem_device *nvmem_register(const struct nvmem_config *config)
+{
+	struct nvmem_device *nvmem;
+	struct device_node *np;
+	int rval;
+
+	if (!config->dev)
+		return ERR_PTR(-EINVAL);
+
+	nvmem = kzalloc(sizeof(*nvmem), GFP_KERNEL);
+	if (!nvmem)
+		return ERR_PTR(-ENOMEM);
+
+	nvmem->stride = config->stride;
+	nvmem->word_size = config->word_size;
+	nvmem->size = config->size;
+	nvmem->dev.parent = config->dev;
+	nvmem->bus = config->bus;
+	np = config->dev->device_node;
+	nvmem->dev.device_node = np;
+
+	nvmem->read_only = of_property_read_bool(np, "read-only") |
+			   config->read_only;
+
+	safe_strncpy(nvmem->dev.name, config->name, MAX_DRIVER_NAME);
+	nvmem->dev.id = DEVICE_ID_DYNAMIC;
+
+	dev_dbg(&nvmem->dev, "Registering nvmem device %s\n", config->name);
+
+	rval = register_device(&nvmem->dev);
+	if (rval) {
+		kfree(nvmem);
+		return ERR_PTR(rval);
+	}
+
+	rval = nvmem_register_cdev(nvmem);
+	if (rval) {
+		kfree(nvmem);
+		return ERR_PTR(rval);
+	}
+
+	list_add_tail(&nvmem->node, &nvmem_devs);
+
+	return nvmem;
+}
+EXPORT_SYMBOL_GPL(nvmem_register);
+
+static struct nvmem_device *__nvmem_device_get(struct device_node *np,
+					       struct nvmem_cell **cellp,
+					       const char *cell_id)
+{
+	struct nvmem_device *nvmem = NULL;
+
+	if (np) {
+		nvmem = of_nvmem_find(np);
+		if (!nvmem)
+			return ERR_PTR(-EPROBE_DEFER);
+	} else {
+		struct nvmem_cell *cell = nvmem_find_cell(cell_id);
+
+		if (cell) {
+			nvmem = cell->nvmem;
+			*cellp = cell;
+		}
+
+		if (!nvmem)
+			return ERR_PTR(-ENOENT);
+	}
+
+	nvmem->users++;
+
+	return nvmem;
+}
+
+static void __nvmem_device_put(struct nvmem_device *nvmem)
+{
+	nvmem->users--;
+}
+
+static struct nvmem_device *nvmem_find(const char *name)
+{
+	return ERR_PTR(-ENOSYS);
+}
+
+#if IS_ENABLED(CONFIG_NVMEM) && IS_ENABLED(CONFIG_OFTREE)
+/**
+ * of_nvmem_device_get() - Get nvmem device from a given id
+ *
+ * @dev node: Device tree node that uses the nvmem device
+ * @id: nvmem name from nvmem-names property.
+ *
+ * Return: ERR_PTR() on error or a valid pointer to a struct nvmem_device
+ * on success.
+ */
+struct nvmem_device *of_nvmem_device_get(struct device_node *np, const char *id)
+{
+
+	struct device_node *nvmem_np;
+	int index;
+
+	index = of_property_match_string(np, "nvmem-names", id);
+
+	nvmem_np = of_parse_phandle(np, "nvmem", index);
+	if (!nvmem_np)
+		return ERR_PTR(-EINVAL);
+
+	return __nvmem_device_get(nvmem_np, NULL, NULL);
+}
+EXPORT_SYMBOL_GPL(of_nvmem_device_get);
+#endif
+
+/**
+ * nvmem_device_get() - Get nvmem device from a given id
+ *
+ * @dev : Device that uses the nvmem device
+ * @id: nvmem name from nvmem-names property.
+ *
+ * Return: ERR_PTR() on error or a valid pointer to a struct nvmem_device
+ * on success.
+ */
+struct nvmem_device *nvmem_device_get(struct device_d *dev, const char *dev_name)
+{
+	if (dev->device_node) { /* try dt first */
+		struct nvmem_device *nvmem;
+
+		nvmem = of_nvmem_device_get(dev->device_node, dev_name);
+
+		if (!IS_ERR(nvmem) || PTR_ERR(nvmem) == -EPROBE_DEFER)
+			return nvmem;
+
+	}
+
+	return nvmem_find(dev_name);
+}
+EXPORT_SYMBOL_GPL(nvmem_device_get);
+
+/**
+ * nvmem_device_put() - put alredy got nvmem device
+ *
+ * @nvmem: pointer to nvmem device that needs to be released.
+ */
+void nvmem_device_put(struct nvmem_device *nvmem)
+{
+	__nvmem_device_put(nvmem);
+}
+EXPORT_SYMBOL_GPL(nvmem_device_put);
+
+static struct nvmem_cell *nvmem_cell_get_from_list(const char *cell_id)
+{
+	struct nvmem_cell *cell = NULL;
+	struct nvmem_device *nvmem;
+
+	nvmem = __nvmem_device_get(NULL, &cell, cell_id);
+	if (IS_ERR(nvmem))
+		return ERR_CAST(nvmem);
+
+	return cell;
+}
+
+#if IS_ENABLED(CONFIG_NVMEM) && IS_ENABLED(CONFIG_OFTREE)
+/**
+ * of_nvmem_cell_get() - Get a nvmem cell from given device node and cell id
+ *
+ * @dev node: Device tree node that uses the nvmem cell
+ * @id: nvmem cell name from nvmem-cell-names property.
+ *
+ * Return: Will be an ERR_PTR() on error or a valid pointer
+ * to a struct nvmem_cell.  The nvmem_cell will be freed by the
+ * nvmem_cell_put().
+ */
+struct nvmem_cell *of_nvmem_cell_get(struct device_node *np,
+					    const char *name)
+{
+	struct device_node *cell_np, *nvmem_np;
+	struct nvmem_cell *cell;
+	struct nvmem_device *nvmem;
+	const __be32 *addr;
+	int rval, len, index;
+
+	index = of_property_match_string(np, "nvmem-cell-names", name);
+
+	cell_np = of_parse_phandle(np, "nvmem-cells", index);
+	if (!cell_np)
+		return ERR_PTR(-EINVAL);
+
+	nvmem_np = of_get_parent(cell_np);
+	if (!nvmem_np)
+		return ERR_PTR(-EINVAL);
+
+	nvmem = __nvmem_device_get(nvmem_np, NULL, NULL);
+	if (IS_ERR(nvmem))
+		return ERR_CAST(nvmem);
+
+	addr = of_get_property(cell_np, "reg", &len);
+	if (!addr || (len < 2 * sizeof(u32))) {
+		dev_err(&nvmem->dev, "nvmem: invalid reg on %s\n",
+			cell_np->full_name);
+		rval  = -EINVAL;
+		goto err_mem;
+	}
+
+	cell = kzalloc(sizeof(*cell), GFP_KERNEL);
+	if (!cell) {
+		rval = -ENOMEM;
+		goto err_mem;
+	}
+
+	cell->nvmem = nvmem;
+	cell->offset = be32_to_cpup(addr++);
+	cell->bytes = be32_to_cpup(addr);
+	cell->name = cell_np->name;
+
+	addr = of_get_property(cell_np, "bits", &len);
+	if (addr && len == (2 * sizeof(u32))) {
+		cell->bit_offset = be32_to_cpup(addr++);
+		cell->nbits = be32_to_cpup(addr);
+	}
+
+	if (cell->nbits)
+		cell->bytes = DIV_ROUND_UP(cell->nbits + cell->bit_offset,
+					   BITS_PER_BYTE);
+
+	if (cell->bytes < nvmem->word_size)
+		cell->bytes = nvmem->word_size;
+
+	if (!IS_ALIGNED(cell->offset, nvmem->stride)) {
+			dev_err(&nvmem->dev,
+				"cell %s unaligned to nvmem stride %d\n",
+				cell->name, nvmem->stride);
+		rval  = -EINVAL;
+		goto err_sanity;
+	}
+
+	nvmem_cell_add(cell);
+
+	return cell;
+
+err_sanity:
+	kfree(cell);
+
+err_mem:
+	__nvmem_device_put(nvmem);
+
+	return ERR_PTR(rval);
+}
+EXPORT_SYMBOL_GPL(of_nvmem_cell_get);
+#endif
+
+/**
+ * nvmem_cell_get() - Get nvmem cell of device form a given cell name
+ *
+ * @dev node: Device tree node that uses the nvmem cell
+ * @id: nvmem cell name to get.
+ *
+ * Return: Will be an ERR_PTR() on error or a valid pointer
+ * to a struct nvmem_cell.  The nvmem_cell will be freed by the
+ * nvmem_cell_put().
+ */
+struct nvmem_cell *nvmem_cell_get(struct device_d *dev, const char *cell_id)
+{
+	struct nvmem_cell *cell;
+
+	if (dev->device_node) { /* try dt first */
+		cell = of_nvmem_cell_get(dev->device_node, cell_id);
+		if (!IS_ERR(cell) || PTR_ERR(cell) == -EPROBE_DEFER)
+			return cell;
+	}
+
+	return nvmem_cell_get_from_list(cell_id);
+}
+EXPORT_SYMBOL_GPL(nvmem_cell_get);
+
+/**
+ * nvmem_cell_put() - Release previously allocated nvmem cell.
+ *
+ * @cell: Previously allocated nvmem cell by nvmem_cell_get()
+ */
+void nvmem_cell_put(struct nvmem_cell *cell)
+{
+	struct nvmem_device *nvmem = cell->nvmem;
+
+	__nvmem_device_put(nvmem);
+	nvmem_cell_drop(cell);
+}
+EXPORT_SYMBOL_GPL(nvmem_cell_put);
+
+static inline void nvmem_shift_read_buffer_in_place(struct nvmem_cell *cell,
+						    void *buf)
+{
+	u8 *p, *b;
+	int i, bit_offset = cell->bit_offset;
+
+	p = b = buf;
+	if (bit_offset) {
+		/* First shift */
+		*b++ >>= bit_offset;
+
+		/* setup rest of the bytes if any */
+		for (i = 1; i < cell->bytes; i++) {
+			/* Get bits from next byte and shift them towards msb */
+			*p |= *b << (BITS_PER_BYTE - bit_offset);
+
+			p = b;
+			*b++ >>= bit_offset;
+		}
+
+		/* result fits in less bytes */
+		if (cell->bytes != DIV_ROUND_UP(cell->nbits, BITS_PER_BYTE))
+			*p-- = 0;
+	}
+	/* clear msb bits if any leftover in the last byte */
+	*p &= GENMASK((cell->nbits%BITS_PER_BYTE) - 1, 0);
+}
+
+static int __nvmem_cell_read(struct nvmem_device *nvmem,
+		      struct nvmem_cell *cell,
+		      void *buf, size_t *len)
+{
+	int rc;
+
+	rc = nvmem->bus->read(&nvmem->dev, cell->offset, buf, cell->bytes);
+	if (IS_ERR_VALUE(rc))
+		return rc;
+
+	/* shift bits in-place */
+	if (cell->bit_offset || cell->nbits)
+		nvmem_shift_read_buffer_in_place(cell, buf);
+
+	*len = cell->bytes;
+
+	return 0;
+}
+
+/**
+ * nvmem_cell_read() - Read a given nvmem cell
+ *
+ * @cell: nvmem cell to be read.
+ * @len: pointer to length of cell which will be populated on successful read.
+ *
+ * Return: ERR_PTR() on error or a valid pointer to a char * buffer on success.
+ * The buffer should be freed by the consumer with a kfree().
+ */
+void *nvmem_cell_read(struct nvmem_cell *cell, size_t *len)
+{
+	struct nvmem_device *nvmem = cell->nvmem;
+	u8 *buf;
+	int rc;
+
+	if (!nvmem)
+		return ERR_PTR(-EINVAL);
+
+	buf = kzalloc(cell->bytes, GFP_KERNEL);
+	if (!buf)
+		return ERR_PTR(-ENOMEM);
+
+	rc = __nvmem_cell_read(nvmem, cell, buf, len);
+	if (IS_ERR_VALUE(rc)) {
+		kfree(buf);
+		return ERR_PTR(rc);
+	}
+
+	return buf;
+}
+EXPORT_SYMBOL_GPL(nvmem_cell_read);
+
+static inline void *nvmem_cell_prepare_write_buffer(struct nvmem_cell *cell,
+						    u8 *_buf, int len)
+{
+	struct nvmem_device *nvmem = cell->nvmem;
+	int i, rc, nbits, bit_offset = cell->bit_offset;
+	u8 v, *p, *buf, *b, pbyte, pbits;
+
+	nbits = cell->nbits;
+	buf = kzalloc(cell->bytes, GFP_KERNEL);
+	if (!buf)
+		return ERR_PTR(-ENOMEM);
+
+	memcpy(buf, _buf, len);
+	p = b = buf;
+
+	if (bit_offset) {
+		pbyte = *b;
+		*b <<= bit_offset;
+
+		/* setup the first byte with lsb bits from nvmem */
+		rc = nvmem->bus->read(&nvmem->dev, cell->offset, &v, 1);
+		*b++ |= GENMASK(bit_offset - 1, 0) & v;
+
+		/* setup rest of the byte if any */
+		for (i = 1; i < cell->bytes; i++) {
+			/* Get last byte bits and shift them towards lsb */
+			pbits = pbyte >> (BITS_PER_BYTE - 1 - bit_offset);
+			pbyte = *b;
+			p = b;
+			*b <<= bit_offset;
+			*b++ |= pbits;
+		}
+	}
+
+	/* if it's not end on byte boundary */
+	if ((nbits + bit_offset) % BITS_PER_BYTE) {
+		/* setup the last byte with msb bits from nvmem */
+		rc = nvmem->bus->read(&nvmem->dev, cell->offset + cell->bytes - 1,
+				      &v, 1);
+		*p |= GENMASK(7, (nbits + bit_offset) % BITS_PER_BYTE) & v;
+
+	}
+
+	return buf;
+}
+
+/**
+ * nvmem_cell_write() - Write to a given nvmem cell
+ *
+ * @cell: nvmem cell to be written.
+ * @buf: Buffer to be written.
+ * @len: length of buffer to be written to nvmem cell.
+ *
+ * Return: length of bytes written or negative on failure.
+ */
+int nvmem_cell_write(struct nvmem_cell *cell, void *buf, size_t len)
+{
+	struct nvmem_device *nvmem = cell->nvmem;
+	int rc;
+
+	if (!nvmem || nvmem->read_only ||
+	    (cell->bit_offset == 0 && len != cell->bytes))
+		return -EINVAL;
+
+	if (cell->bit_offset || cell->nbits) {
+		buf = nvmem_cell_prepare_write_buffer(cell, buf, len);
+		if (IS_ERR(buf))
+			return PTR_ERR(buf);
+	}
+
+	rc = nvmem->bus->write(&nvmem->dev, cell->offset, buf, cell->bytes);
+
+	/* free the tmp buffer */
+	if (cell->bit_offset || cell->nbits)
+		kfree(buf);
+
+	if (IS_ERR_VALUE(rc))
+		return rc;
+
+	return len;
+}
+EXPORT_SYMBOL_GPL(nvmem_cell_write);
+
+/**
+ * nvmem_device_cell_read() - Read a given nvmem device and cell
+ *
+ * @nvmem: nvmem device to read from.
+ * @info: nvmem cell info to be read.
+ * @buf: buffer pointer which will be populated on successful read.
+ *
+ * Return: length of successful bytes read on success and negative
+ * error code on error.
+ */
+ssize_t nvmem_device_cell_read(struct nvmem_device *nvmem,
+			   struct nvmem_cell_info *info, void *buf)
+{
+	struct nvmem_cell cell;
+	int rc;
+	ssize_t len;
+
+	if (!nvmem)
+		return -EINVAL;
+
+	rc = nvmem_cell_info_to_nvmem_cell(nvmem, info, &cell);
+	if (IS_ERR_VALUE(rc))
+		return rc;
+
+	rc = __nvmem_cell_read(nvmem, &cell, buf, &len);
+	if (IS_ERR_VALUE(rc))
+		return rc;
+
+	return len;
+}
+EXPORT_SYMBOL_GPL(nvmem_device_cell_read);
+
+/**
+ * nvmem_device_cell_write() - Write cell to a given nvmem device
+ *
+ * @nvmem: nvmem device to be written to.
+ * @info: nvmem cell info to be written
+ * @buf: buffer to be written to cell.
+ *
+ * Return: length of bytes written or negative error code on failure.
+ * */
+int nvmem_device_cell_write(struct nvmem_device *nvmem,
+			    struct nvmem_cell_info *info, void *buf)
+{
+	struct nvmem_cell cell;
+	int rc;
+
+	if (!nvmem)
+		return -EINVAL;
+
+	rc = nvmem_cell_info_to_nvmem_cell(nvmem, info, &cell);
+	if (IS_ERR_VALUE(rc))
+		return rc;
+
+	return nvmem_cell_write(&cell, buf, cell.bytes);
+}
+EXPORT_SYMBOL_GPL(nvmem_device_cell_write);
+
+/**
+ * nvmem_device_read() - Read from a given nvmem device
+ *
+ * @nvmem: nvmem device to read from.
+ * @offset: offset in nvmem device.
+ * @bytes: number of bytes to read.
+ * @buf: buffer pointer which will be populated on successful read.
+ *
+ * Return: length of successful bytes read on success and negative
+ * error code on error.
+ */
+int nvmem_device_read(struct nvmem_device *nvmem,
+		      unsigned int offset,
+		      size_t bytes, void *buf)
+{
+	int rc;
+
+	if (!nvmem)
+		return -EINVAL;
+
+	if (offset >= nvmem->size || bytes > nvmem->size - offset)
+		return -EINVAL;
+
+	if (!bytes)
+		return 0;
+
+	rc = nvmem->bus->read(&nvmem->dev, offset, buf, bytes);
+
+	if (IS_ERR_VALUE(rc))
+		return rc;
+
+	return bytes;
+}
+EXPORT_SYMBOL_GPL(nvmem_device_read);
+
+/**
+ * nvmem_device_write() - Write cell to a given nvmem device
+ *
+ * @nvmem: nvmem device to be written to.
+ * @offset: offset in nvmem device.
+ * @bytes: number of bytes to write.
+ * @buf: buffer to be written.
+ *
+ * Return: length of bytes written or negative error code on failure.
+ * */
+int nvmem_device_write(struct nvmem_device *nvmem,
+		       unsigned int offset,
+		       size_t bytes, const void *buf)
+{
+	int rc;
+
+	if (!nvmem || nvmem->read_only)
+		return -EINVAL;
+
+	if (offset >= nvmem->size || bytes > nvmem->size - offset)
+		return -EINVAL;
+
+	if (!bytes)
+		return 0;
+
+	rc = nvmem->bus->write(&nvmem->dev, offset, buf, bytes);
+
+	if (IS_ERR_VALUE(rc))
+		return rc;
+
+
+	return bytes;
+}
+EXPORT_SYMBOL_GPL(nvmem_device_write);
diff --git a/drivers/nvmem/snvs_lpgpr.c b/drivers/nvmem/snvs_lpgpr.c
new file mode 100644
index 0000000000..74118a6b75
--- /dev/null
+++ b/drivers/nvmem/snvs_lpgpr.c
@@ -0,0 +1,115 @@
+/*
+ * Copyright (c) 2015 Pengutronix, Steffen Trumtrar <kernel@pengutronix.de>
+ * Copyright (c) 2017 Pengutronix, Oleksij Rempel <kernel@pengutronix.de>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2
+ * as published by the Free Software Foundation.
+ */
+#include <common.h>
+#include <driver.h>
+#include <init.h>
+#include <io.h>
+#include <of.h>
+#include <malloc.h>
+#include <regmap.h>
+#include <mfd/syscon.h>
+#include <linux/nvmem-provider.h>
+
+struct snvs_lpgpr_priv {
+	struct device_d		*dev;
+	struct regmap		*regmap;
+	int			offset;
+	struct nvmem_config	cfg;
+};
+
+static int snvs_lpgpr_write(struct device_d *dev, const int reg,
+			    const void *_val, int bytes)
+{
+	struct snvs_lpgpr_priv *priv = dev->parent->priv;
+	const u32 *val = _val;
+	int i = 0, words = bytes / 4;
+
+	while (words--)
+		regmap_write(priv->regmap, priv->offset + reg + (i++ * 4),
+			     *val++);
+
+	return 0;
+}
+
+static int snvs_lpgpr_read(struct device_d *dev, const int reg, void *_val,
+			int bytes)
+{
+	struct snvs_lpgpr_priv *priv = dev->parent->priv;
+	u32 *val = _val;
+	int i = 0, words = bytes / 4;
+
+	while (words--)
+		regmap_read(priv->regmap, priv->offset + reg + (i++ * 4),
+			    val++);
+
+
+	return 0;
+}
+
+static const struct nvmem_bus snvs_lpgpr_nvmem_bus = {
+	.write = snvs_lpgpr_write,
+	.read  = snvs_lpgpr_read,
+};
+
+static int snvs_lpgpr_probe(struct device_d *dev)
+{
+	struct device_node *node = dev->device_node;
+	struct snvs_lpgpr_priv *priv;
+	struct nvmem_config *cfg;
+	struct nvmem_device *nvmem;
+	int err;
+
+	if (!node)
+		return -ENOENT;
+
+	priv = kzalloc(sizeof(*priv), GFP_KERNEL);
+	if (!priv)
+		return -ENOMEM;
+
+	priv->regmap = syscon_node_to_regmap(of_get_parent(node));
+	if (IS_ERR(priv->regmap)) {
+		free(priv);
+		return PTR_ERR(priv->regmap);
+	}
+
+	err = of_property_read_u32(node, "offset", &priv->offset);
+	if (err)
+		return err;
+
+	cfg = &priv->cfg;
+	cfg->name = dev_name(dev);
+	cfg->dev = dev;
+	cfg->stride = 4,
+	cfg->word_size = 4,
+	cfg->size = 4,
+	cfg->bus = &snvs_lpgpr_nvmem_bus,
+
+	nvmem = nvmem_register(cfg);
+	if (IS_ERR(nvmem)) {
+		free(priv);
+		return PTR_ERR(nvmem);
+	}
+
+	dev->priv = priv;
+
+	return 0;
+}
+
+static __maybe_unused struct of_device_id snvs_lpgpr_dt_ids[] = {
+	{ .compatible = "fsl,imx6sl-snvs-lpgpr", },
+	{ .compatible = "fsl,imx6q-snvs-lpgpr", },
+	{ },
+};
+
+static struct driver_d snvs_lpgpr_driver = {
+	.name	= "nvmem-snvs-lpgpr",
+	.probe	= snvs_lpgpr_probe,
+	.of_compatible = DRV_OF_COMPAT(snvs_lpgpr_dt_ids),
+};
+device_platform_driver(snvs_lpgpr_driver);
diff --git a/dts/src/arm/imx6qdl.dtsi b/dts/src/arm/imx6qdl.dtsi
index 6d7bf64961..8e90014705 100644
--- a/dts/src/arm/imx6qdl.dtsi
+++ b/dts/src/arm/imx6qdl.dtsi
@@ -768,6 +768,12 @@
 					mask = <0x60>;
 					status = "disabled";
 				};
+
+				snvs_lpgpr: snvs-lpgpr {
+					compatible = "fsl,imx6q-snvs-lpgpr";
+					regmap = <&snvs>;
+					offset = <0x68>;
+				};
 			};
 
 			epit1: epit@020d0000 { /* EPIT1 */
diff --git a/dts/src/arm/imx6sl.dtsi b/dts/src/arm/imx6sl.dtsi
index cc9572ea28..eeafba04cf 100644
--- a/dts/src/arm/imx6sl.dtsi
+++ b/dts/src/arm/imx6sl.dtsi
@@ -655,6 +655,12 @@
 					mask = <0x60>;
 					status = "disabled";
 				};
+
+				snvs_lpgpr: snvs-lpgpr {
+					compatible = "fsl,imx6sl-snvs-lpgpr";
+					regmap = <&snvs>;
+					offset = <0x68>;
+				};
 			};
 
 			epit1: epit@020d0000 {
diff --git a/include/linux/nvmem-consumer.h b/include/linux/nvmem-consumer.h
new file mode 100644
index 0000000000..606cadb498
--- /dev/null
+++ b/include/linux/nvmem-consumer.h
@@ -0,0 +1,94 @@
+/*
+ * nvmem framework consumer.
+ *
+ * Copyright (C) 2015 Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
+ * Copyright (C) 2013 Maxime Ripard <maxime.ripard@free-electrons.com>
+ *
+ * This file is licensed under the terms of the GNU General Public
+ * License version 2.  This program is licensed "as is" without any
+ * warranty of any kind, whether express or implied.
+ */
+
+#ifndef _LINUX_NVMEM_CONSUMER_H
+#define _LINUX_NVMEM_CONSUMER_H
+
+struct device_d;
+struct device_node;
+/* consumer cookie */
+struct nvmem_cell;
+struct nvmem_device;
+
+struct nvmem_cell_info {
+	const char		*name;
+	unsigned int		offset;
+	unsigned int		bytes;
+	unsigned int		bit_offset;
+	unsigned int		nbits;
+};
+
+#if IS_ENABLED(CONFIG_NVMEM)
+
+/* Cell based interface */
+struct nvmem_cell *nvmem_cell_get(struct device_d *dev, const char *name);
+void nvmem_cell_put(struct nvmem_cell *cell);
+void *nvmem_cell_read(struct nvmem_cell *cell, size_t *len);
+int nvmem_cell_write(struct nvmem_cell *cell, void *buf, size_t len);
+
+/* direct nvmem device read/write interface */
+struct nvmem_device *nvmem_device_get(struct device_d *dev, const char *name);
+void nvmem_device_put(struct nvmem_device *nvmem);
+
+#else
+
+static inline struct nvmem_cell *nvmem_cell_get(struct device_d *dev,
+						const char *name)
+{
+	return ERR_PTR(-ENOSYS);
+}
+
+static inline void nvmem_cell_put(struct nvmem_cell *cell)
+{
+}
+
+static inline char *nvmem_cell_read(struct nvmem_cell *cell, size_t *len)
+{
+	return ERR_PTR(-ENOSYS);
+}
+
+static inline int nvmem_cell_write(struct nvmem_cell *cell,
+				    const char *buf, size_t len)
+{
+	return -ENOSYS;
+}
+
+static inline struct nvmem_device *nvmem_device_get(struct device_d *dev,
+						    const char *name)
+{
+	return ERR_PTR(-ENOSYS);
+}
+
+static inline void nvmem_device_put(struct nvmem_device *nvmem)
+{
+}
+#endif /* CONFIG_NVMEM */
+
+#if IS_ENABLED(CONFIG_NVMEM) && IS_ENABLED(CONFIG_OFTREE)
+struct nvmem_cell *of_nvmem_cell_get(struct device_node *np,
+				     const char *name);
+struct nvmem_device *of_nvmem_device_get(struct device_node *np,
+					 const char *name);
+#else
+static inline struct nvmem_cell *of_nvmem_cell_get(struct device_node *np,
+				     const char *name)
+{
+	return ERR_PTR(-ENOSYS);
+}
+
+static inline struct nvmem_device *of_nvmem_device_get(struct device_node *np,
+						       const char *name)
+{
+	return ERR_PTR(-ENOSYS);
+}
+#endif /* CONFIG_NVMEM && CONFIG_OF */
+
+#endif  /* ifndef _LINUX_NVMEM_CONSUMER_H */
diff --git a/include/linux/nvmem-provider.h b/include/linux/nvmem-provider.h
new file mode 100644
index 0000000000..6ef5ea6854
--- /dev/null
+++ b/include/linux/nvmem-provider.h
@@ -0,0 +1,49 @@
+/*
+ * nvmem framework provider.
+ *
+ * Copyright (C) 2015 Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
+ * Copyright (C) 2013 Maxime Ripard <maxime.ripard@free-electrons.com>
+ *
+ * This file is licensed under the terms of the GNU General Public
+ * License version 2.  This program is licensed "as is" without any
+ * warranty of any kind, whether express or implied.
+ */
+
+#ifndef _LINUX_NVMEM_PROVIDER_H
+#define _LINUX_NVMEM_PROVIDER_H
+
+#include <common.h>
+#include <linux/types.h>
+
+struct nvmem_device;
+
+struct nvmem_bus {
+	int (*write)(struct device_d *dev, const int reg, const void *val,
+		     int val_size);
+	int (*read)(struct device_d *dev, const int reg, void *val,
+		    int val_size);
+};
+
+struct nvmem_config {
+	struct device_d		*dev;
+	const char		*name;
+	bool			read_only;
+	int			stride;
+	int			word_size;
+	int			size;
+	const struct nvmem_bus	*bus;
+};
+
+#if IS_ENABLED(CONFIG_NVMEM)
+
+struct nvmem_device *nvmem_register(const struct nvmem_config *cfg);
+
+#else
+
+static inline struct nvmem_device *nvmem_register(const struct nvmem_config *c)
+{
+	return ERR_PTR(-ENOSYS);
+}
+
+#endif /* CONFIG_NVMEM */
+#endif  /* ifndef _LINUX_NVMEM_PROVIDER_H */