[PATCH] Add nvmem support

[PATCH] Add nvmem support

[Sascha Hauer]

This ports over the nvmem framework from the kernel. I probably won't
apply it as is since it doesn't make me very happy. While it generally
works the very first test already reveals that it can't properly handle
the different layouts of nvmem cells. The MAC addresses for the i.MX
FEC are stored in different byte orders in the IIM/OCOTP units. There's
simply no proper place to encode these different byte orders, see patch
[2/2].

Sascha

----------------------------------------------------------------
Sascha Hauer (1):
      nvmem: Test it with fec/ocotp

Steffen Trumtrar (1):
      drivers: add nvmem framework from kernel

 arch/arm/dts/imx6qdl-phytec-pfla02.dtsi |   9 +
 arch/arm/mach-imx/ocotp.c               |   8 +
 drivers/Kconfig                         |   1 +
 drivers/Makefile                        |   1 +
 drivers/net/fec_imx.c                   |  30 ++
 drivers/nvmem/Kconfig                   |   8 +
 drivers/nvmem/Makefile                  |   6 +
 drivers/nvmem/core.c                    | 749 ++++++++++++++++++++++++++++++++
 include/linux/nvmem-consumer.h          | 157 +++++++
 include/linux/nvmem-provider.h          |  49 +++
 10 files changed, 1018 insertions(+)
 create mode 100644 drivers/nvmem/Kconfig
 create mode 100644 drivers/nvmem/Makefile
 create mode 100644 drivers/nvmem/core.c
 create mode 100644 include/linux/nvmem-consumer.h
 create mode 100644 include/linux/nvmem-provider.h

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[PATCH 1/2] drivers: add nvmem framework from kernel

[Sascha Hauer]

From: Steffen Trumtrar <s.trumtrar@pengutronix.de>

Add the nvmem framework from Linux.

Based on the v4.4-rc3 version.

Signed-off-by: Steffen Trumtrar <s.trumtrar@pengutronix.de>
---
 drivers/Kconfig                |   1 +
 drivers/Makefile               |   1 +
 drivers/nvmem/Kconfig          |   8 +
 drivers/nvmem/Makefile         |   6 +
 drivers/nvmem/core.c           | 749 +++++++++++++++++++++++++++++++++++++++++
 include/linux/nvmem-consumer.h | 157 +++++++++
 include/linux/nvmem-provider.h |  49 +++
 7 files changed, 971 insertions(+)
 create mode 100644 drivers/nvmem/Kconfig
 create mode 100644 drivers/nvmem/Makefile
 create mode 100644 drivers/nvmem/core.c
 create mode 100644 include/linux/nvmem-consumer.h
 create mode 100644 include/linux/nvmem-provider.h

diff --git a/drivers/Kconfig b/drivers/Kconfig
index 5984ccc..3b2ea4d 100644
--- a/drivers/Kconfig
+++ b/drivers/Kconfig
@@ -31,5 +31,6 @@ source "drivers/pci/Kconfig"
 source "drivers/rtc/Kconfig"
 source "drivers/firmware/Kconfig"
 source "drivers/phy/Kconfig"
+source "drivers/nvmem/Kconfig"
 
 endmenu
diff --git a/drivers/Makefile b/drivers/Makefile
index 3afbb61..3d7f328 100644
--- a/drivers/Makefile
+++ b/drivers/Makefile
@@ -31,3 +31,4 @@ obj-y += rtc/
 obj-$(CONFIG_FIRMWARE) += firmware/
 obj-$(CONFIG_GENERIC_PHY) += phy/
 obj-$(CONFIG_HABV4) += habv4/
+obj-$(CONFIG_NVMEM) += nvmem/
diff --git a/drivers/nvmem/Kconfig b/drivers/nvmem/Kconfig
new file mode 100644
index 0000000..218be05
--- /dev/null
+++ b/drivers/nvmem/Kconfig
@@ -0,0 +1,8 @@
+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.
diff --git a/drivers/nvmem/Makefile b/drivers/nvmem/Makefile
new file mode 100644
index 0000000..6df2c69
--- /dev/null
+++ b/drivers/nvmem/Makefile
@@ -0,0 +1,6 @@
+#
+# Makefile for nvmem drivers.
+#
+
+obj-$(CONFIG_NVMEM)		+= nvmem_core.o
+nvmem_core-y			:= core.o
diff --git a/drivers/nvmem/core.c b/drivers/nvmem/core.c
new file mode 100644
index 0000000..0214253
--- /dev/null
+++ b/drivers/nvmem/core.c
@@ -0,0 +1,749 @@
+/*
+ * 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.
+ */
+#define DEBUG
+#include <common.h>
+#include <libbb.h>
+#include <malloc.h>
+#include <of.h>
+#include <regmap.h>
+#include <linux/nvmem-consumer.h>
+#include <linux/nvmem-provider.h>
+
+struct nvmem_device {
+	const char		*name;
+	struct device_d		dev;
+	struct nvmem_bus	*bus;
+	struct list_head	node;
+	int			stride;
+	int			word_size;
+	int			ncells;
+	int			users;
+	size_t			size;
+	bool			read_only;
+	struct regmap		*regmap;
+};
+
+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);
+
+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_device_remove_all_cells(const struct nvmem_device *nvmem)
+{
+	struct nvmem_cell *cell;
+	struct list_head *p, *n;
+
+	list_for_each_safe(p, n, &nvmem_cells) {
+		cell = list_entry(p, struct nvmem_cell, node);
+		if (cell->nvmem == nvmem)
+			nvmem_cell_drop(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;
+}
+
+static int nvmem_add_cells(struct nvmem_device *nvmem,
+			   const struct nvmem_config *cfg)
+{
+	struct nvmem_cell **cells;
+	const struct nvmem_cell_info *info = cfg->cells;
+	int i, rval;
+
+	cells = kzalloc(sizeof(*cells)*cfg->ncells, GFP_KERNEL);
+	if (!cells)
+		return -ENOMEM;
+
+	for (i = 0; i < cfg->ncells; i++) {
+		cells[i] = kzalloc(sizeof(**cells), GFP_KERNEL);
+		if (!cells[i]) {
+			rval = -ENOMEM;
+			goto err;
+		}
+
+		rval = nvmem_cell_info_to_nvmem_cell(nvmem, &info[i], cells[i]);
+		if (IS_ERR_VALUE(rval)) {
+			kfree(cells[i]);
+			goto err;
+		}
+
+		nvmem_cell_add(cells[i]);
+	}
+
+	nvmem->ncells = cfg->ncells;
+	/* remove tmp array */
+	kfree(cells);
+
+	return 0;
+err:
+	while (--i)
+		nvmem_cell_drop(cells[i]);
+
+	return rval;
+}
+
+/**
+ * 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 regmap *map)
+{
+	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 = regmap_get_reg_stride(map);
+	nvmem->word_size = regmap_get_val_bytes(map);
+	nvmem->size = regmap_get_max_register(map) + nvmem->stride;
+	nvmem->dev.parent = config->dev;
+	nvmem->regmap = map;
+	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);
+	}
+
+	list_add_tail(&nvmem->node, &nvmem_devs);
+
+	if (config->cells)
+		nvmem_add_cells(nvmem, config);
+
+	return nvmem;
+}
+EXPORT_SYMBOL_GPL(nvmem_register);
+
+/**
+ * nvmem_unregister() - Unregister previously registered nvmem device
+ *
+ * @nvmem: Pointer to previously registered nvmem device.
+ *
+ * Return: Will be an negative on error or a zero on success.
+ */
+int nvmem_unregister(struct nvmem_device *nvmem)
+{
+	if (nvmem->users)
+		return -EBUSY;
+
+	nvmem_device_remove_all_cells(nvmem);
+	unregister_device(&nvmem->dev);
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(nvmem_unregister);
+
+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--;
+}
+
+#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 ERR_PTR(-ENOENT);
+}
+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);
+	if (index < 0)
+		return ERR_PTR(index);
+
+	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 = regmap_bulk_read(nvmem->regmap, 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 = regmap_bulk_read(nvmem->regmap, 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 = regmap_bulk_read(nvmem->regmap, 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 = regmap_bulk_write(nvmem->regmap, 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;
+
+	rc = regmap_bulk_read(nvmem->regmap, 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, void *buf)
+{
+	int rc;
+
+	if (!nvmem)
+		return -EINVAL;
+
+	rc = regmap_bulk_write(nvmem->regmap, offset, buf, bytes);
+
+	if (IS_ERR_VALUE(rc))
+		return rc;
+
+
+	return bytes;
+}
+EXPORT_SYMBOL_GPL(nvmem_device_write);
diff --git a/include/linux/nvmem-consumer.h b/include/linux/nvmem-consumer.h
new file mode 100644
index 0000000..cae6ec7
--- /dev/null
+++ b/include/linux/nvmem-consumer.h
@@ -0,0 +1,157 @@
+/*
+ * 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);
+struct nvmem_cell *devm_nvmem_cell_get(struct device_d *dev, const char *name);
+void nvmem_cell_put(struct nvmem_cell *cell);
+void devm_nvmem_cell_put(struct device_d *dev, 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);
+struct nvmem_device *devm_nvmem_device_get(struct device_d *dev,
+					   const char *name);
+void nvmem_device_put(struct nvmem_device *nvmem);
+void devm_nvmem_device_put(struct device_d *dev, struct nvmem_device *nvmem);
+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, void *buf);
+ssize_t nvmem_device_cell_read(struct nvmem_device *nvmem,
+			   struct nvmem_cell_info *info, void *buf);
+int nvmem_device_cell_write(struct nvmem_device *nvmem,
+			    struct nvmem_cell_info *info, void *buf);
+
+#else
+
+static inline struct nvmem_cell *nvmem_cell_get(struct device_d *dev,
+						const char *name)
+{
+	return ERR_PTR(-ENOSYS);
+}
+
+static inline struct nvmem_cell *devm_nvmem_cell_get(struct device_d *dev,
+				       const char *name)
+{
+	return ERR_PTR(-ENOSYS);
+}
+
+static inline void devm_nvmem_cell_put(struct device_d *dev,
+				       struct nvmem_cell *cell)
+{
+
+}
+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 struct nvmem_device *devm_nvmem_device_get(struct device_d *dev,
+							 const char *name)
+{
+	return ERR_PTR(-ENOSYS);
+}
+
+static inline void nvmem_device_put(struct nvmem_device *nvmem)
+{
+}
+
+static inline void devm_nvmem_device_put(struct device_d *dev,
+					 struct nvmem_device *nvmem)
+{
+}
+
+static inline ssize_t nvmem_device_cell_read(struct nvmem_device *nvmem,
+					 struct nvmem_cell_info *info,
+					 void *buf)
+{
+	return -ENOSYS;
+}
+
+static inline int nvmem_device_cell_write(struct nvmem_device *nvmem,
+					  struct nvmem_cell_info *info,
+					  void *buf)
+{
+	return -ENOSYS;
+}
+
+static inline int nvmem_device_read(struct nvmem_device *nvmem,
+				    unsigned int offset, size_t bytes,
+				    void *buf)
+{
+	return -ENOSYS;
+}
+
+static inline int nvmem_device_write(struct nvmem_device *nvmem,
+				     unsigned int offset, size_t bytes,
+				     void *buf)
+{
+	return -ENOSYS;
+}
+#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 0000000..99605a9
--- /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
+
+struct device_d;
+struct nvmem_device;
+struct nvmem_cell_info;
+
+struct nvmem_config {
+	struct device_d		*dev;
+	const char		*name;
+	int			id;
+	const struct nvmem_cell_info	*cells;
+	int			ncells;
+	bool			read_only;
+};
+
+#if IS_ENABLED(CONFIG_NVMEM)
+
+struct nvmem_device *nvmem_register(const struct nvmem_config *cfg,
+				    struct regmap *map);
+int nvmem_unregister(struct nvmem_device *nvmem);
+
+#else
+
+static inline struct nvmem_device *nvmem_register(const struct nvmem_config *c,
+						  struct regmap *map);
+{
+	return ERR_PTR(-ENOSYS);
+}
+
+static inline int nvmem_unregister(struct nvmem_device *nvmem)
+{
+	return -ENOSYS;
+}
+
+#endif /* CONFIG_NVMEM */
+
+#endif  /* ifndef _LINUX_NVMEM_PROVIDER_H */
-- 
2.7.0.rc3


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[PATCH 2/2] nvmem: Test it with fec/ocotp

[Sascha Hauer]

This adds a test for the nvmem framework. The ocotp is registered as a
nvmem device which shall provide the MAC address for the i.MX FEC
driver.

While this generally works it reveals a shortcoming of the nvmem
framework: There's no way to specify the layout of the cell. For example
the MAC address stored in the OCOTP has another byte order than
the one stored in the IIM module on older i.MX SoCs. The FEC driver
shouldn't know about these differences, so it shouldn't be implemented
there. The OCOTP and IIM drivers are generic drivers used on different
SoCs aswell, so the differences shouldn't be encoded there either.
This leaves the device tree to put the differences in, but this simple
example already shows how complex such a binding probably becomes when
all kinds of different possibilities of byte orders shall be encoded.
What's missing is some kind of mapping driver that could be plugged
between a nvmem provider and its consumer where all these differences
can be handled.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
---
 arch/arm/dts/imx6qdl-phytec-pfla02.dtsi |  9 +++++++++
 arch/arm/mach-imx/ocotp.c               |  8 ++++++++
 drivers/net/fec_imx.c                   | 30 ++++++++++++++++++++++++++++++
 3 files changed, 47 insertions(+)

diff --git a/arch/arm/dts/imx6qdl-phytec-pfla02.dtsi b/arch/arm/dts/imx6qdl-phytec-pfla02.dtsi
index b79ce2c..c5f25f9 100644
--- a/arch/arm/dts/imx6qdl-phytec-pfla02.dtsi
+++ b/arch/arm/dts/imx6qdl-phytec-pfla02.dtsi
@@ -85,6 +85,8 @@
 
 &fec {
 	phy-handle = <&ethphy>;
+	nvmem-cells = <&fec_mac_address>;
+	nvmem-cell-names = "mac-address";
 
 	mdio {
 		#address-cells = <1>;
@@ -171,7 +173,14 @@
 };
 
 &ocotp {
+	#address-cells = <1>;
+	#size-cells = <1>;
+
 	barebox,provide-mac-address = <&fec 0x620>;
+
+	fec_mac_address: mac_address@88 {
+		reg = <0x88 0x8>;
+	};
 };
 
 &usdhc3 {
diff --git a/arch/arm/mach-imx/ocotp.c b/arch/arm/mach-imx/ocotp.c
index c6c341d..c8ba932 100644
--- a/arch/arm/mach-imx/ocotp.c
+++ b/arch/arm/mach-imx/ocotp.c
@@ -28,6 +28,7 @@
 #include <clock.h>
 #include <regmap.h>
 #include <linux/clk.h>
+#include <linux/nvmem-provider.h>
 
 /*
  * a single MAC address reference has the form
@@ -79,6 +80,7 @@ struct ocotp_priv {
 	int permanent_write_enable;
 	int sense_enable;
 	char ethaddr[6];
+	struct nvmem_config nvmem_config;
 };
 
 static int imx6_ocotp_set_timing(struct ocotp_priv *priv)
@@ -404,6 +406,12 @@ static int imx_ocotp_probe(struct device_d *dev)
         if (ret)
                 return ret;
 
+	priv->nvmem_config.name = "imx-ocotp",
+	priv->nvmem_config.read_only = true,
+	priv->nvmem_config.dev = dev;
+
+	nvmem_register(&priv->nvmem_config, priv->map);
+
 	if (IS_ENABLED(CONFIG_IMX_OCOTP_WRITE)) {
 		dev_add_param_bool(&(priv->dev), "permanent_write_enable",
 				NULL, NULL, &priv->permanent_write_enable, NULL);
diff --git a/drivers/net/fec_imx.c b/drivers/net/fec_imx.c
index 5418034..0448b51 100644
--- a/drivers/net/fec_imx.c
+++ b/drivers/net/fec_imx.c
@@ -621,6 +621,34 @@ static int fec_alloc_receive_packets(struct fec_priv *fec, int count, int size)
 	return 0;
 }
 
+#include <linux/nvmem-consumer.h>
+
+static void nvmem_test(struct device_d *dev)
+{
+	struct nvmem_cell *cell;
+	uint8_t *buf;
+	int len, i;
+
+	cell = nvmem_cell_get(dev, "mac-address");
+	if (IS_ERR(cell)) {
+		dev_err(dev, "Failed to get cell: %s\n", strerrorp(cell));
+	}
+
+	buf = nvmem_cell_read(cell, &len);
+	if (IS_ERR(buf)) {
+		dev_err(dev, "Failed to read cell: %s\n", strerrorp(buf));
+	}
+
+	printf("buf: 0x%p len %d\n", buf, len);
+
+	for (i = 0; i < len; i++)
+		printf("%02x ", buf[i]);
+
+	printf("\n");
+
+	free(buf);
+}
+
 #ifdef CONFIG_OFDEVICE
 static int fec_probe_dt(struct device_d *dev, struct fec_priv *fec)
 {
@@ -637,6 +665,8 @@ static int fec_probe_dt(struct device_d *dev, struct fec_priv *fec)
 	if (mdiobus)
 		fec->miibus.dev.device_node = mdiobus;
 
+	nvmem_test(dev);
+
 	return 0;
 }
 #else
-- 
2.7.0.rc3


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Re: [PATCH 2/2] nvmem: Test it with fec/ocotp

[Trent Piepho]

On Wed, 2016-02-03 at 17:27 +0100, Sascha Hauer wrote:
> While this generally works it reveals a shortcoming of the nvmem
> framework: There's no way to specify the layout of the cell. For example
> the MAC address stored in the OCOTP has another byte order than
> the one stored in the IIM module on older i.MX SoCs. The FEC driver
> shouldn't know about these differences, so it shouldn't be implemented
> there. The OCOTP and IIM drivers are generic drivers used on different
> SoCs aswell, so the differences shouldn't be encoded there either.
> This leaves the device tree to put the differences in, but this simple
> example already shows how complex such a binding probably becomes when
> all kinds of different possibilities of byte orders shall be encoded.
> What's missing is some kind of mapping driver that could be plugged
> between a nvmem provider and its consumer where all these differences
> can be handled.

>  
>  &fec {
>  	phy-handle = <&ethphy>;
> +	nvmem-cells = <&fec_mac_address>;
> +	nvmem-cell-names = "mac-address";
>  
>  	mdio {
>  		#address-cells = <1>;
> @@ -171,7 +173,14 @@
>  };
>  
>  &ocotp {
> +	#address-cells = <1>;
> +	#size-cells = <1>;
> +
>  	barebox,provide-mac-address = <&fec 0x620>;
> +
> +	fec_mac_address: mac_address@88 {
> +		reg = <0x88 0x8>;
> +	};
>  };

Why is there both a nvmem-cells = <&fec_mac_address> property in the fec
and also a barebox,provide-mac-address = <&fec 0x620> property in the
ocotp?  It seems like only one should need to point to the other.


Here's an idea for an nvmem property for coping byteorder, etc.


fec_mac_address: mac_address@88 {
        reg = <0x88 0x8>;
        map = [1 2 3 4 5 6 0 0];  // Leftmost octet first order
        map = [6 5 4 3 2 1 0 0];  // Rightmost octet first order

        // Leftmost first, but with opposite byte order within each word
        map = [4 3 2 1 0 0 6 5];

        // Only extension is stored
        reg = <0x88 4>; // Just four bytes are used
        map = [4 5 6 0];
};

The idea is the map property lists the destination location of each byte
in the reg range.  The first item in map is the location of the first
byte in the range, a value of one (not zero) indicates it should be the
first byte in the output, 2 the second byte, and so on.  0 means the
byte isn't used.  It's pretty common to use use six bytes inside a 8
byte field for a mac.
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Re: [PATCH 2/2] nvmem: Test it with fec/ocotp

[Sascha Hauer]

On Wed, Feb 03, 2016 at 07:01:03PM +0000, Trent Piepho wrote:
> On Wed, 2016-02-03 at 17:27 +0100, Sascha Hauer wrote:
> > While this generally works it reveals a shortcoming of the nvmem
> > framework: There's no way to specify the layout of the cell. For example
> > the MAC address stored in the OCOTP has another byte order than
> > the one stored in the IIM module on older i.MX SoCs. The FEC driver
> > shouldn't know about these differences, so it shouldn't be implemented
> > there. The OCOTP and IIM drivers are generic drivers used on different
> > SoCs aswell, so the differences shouldn't be encoded there either.
> > This leaves the device tree to put the differences in, but this simple
> > example already shows how complex such a binding probably becomes when
> > all kinds of different possibilities of byte orders shall be encoded.
> > What's missing is some kind of mapping driver that could be plugged
> > between a nvmem provider and its consumer where all these differences
> > can be handled.
> 
> >  
> >  &fec {
> >  	phy-handle = <&ethphy>;
> > +	nvmem-cells = <&fec_mac_address>;
> > +	nvmem-cell-names = "mac-address";
> >  
> >  	mdio {
> >  		#address-cells = <1>;
> > @@ -171,7 +173,14 @@
> >  };
> >  
> >  &ocotp {
> > +	#address-cells = <1>;
> > +	#size-cells = <1>;
> > +
> >  	barebox,provide-mac-address = <&fec 0x620>;
> > +
> > +	fec_mac_address: mac_address@88 {
> > +		reg = <0x88 0x8>;
> > +	};
> >  };
> 
> Why is there both a nvmem-cells = <&fec_mac_address> property in the fec
> and also a barebox,provide-mac-address = <&fec 0x620> property in the
> ocotp?  It seems like only one should need to point to the other.

Yes, finally only one is needed. The patch is for testing purposes only
at the moment.

> 
> 
> Here's an idea for an nvmem property for coping byteorder, etc.
> 
> 
> fec_mac_address: mac_address@88 {
>         reg = <0x88 0x8>;
>         map = [1 2 3 4 5 6 0 0];  // Leftmost octet first order
>         map = [6 5 4 3 2 1 0 0];  // Rightmost octet first order
> 
>         // Leftmost first, but with opposite byte order within each word
>         map = [4 3 2 1 0 0 6 5];
> 
>         // Only extension is stored
>         reg = <0x88 4>; // Just four bytes are used
>         map = [4 5 6 0];
> };
> 
> The idea is the map property lists the destination location of each byte
> in the reg range.  The first item in map is the location of the first
> byte in the range, a value of one (not zero) indicates it should be the
> first byte in the output, 2 the second byte, and so on.  0 means the
> byte isn't used.  It's pretty common to use use six bytes inside a 8
> byte field for a mac.

I guess that would work for this case. The binding as it is documented
currently allows a 'bits' property:

bits:	Is pair of bit location and number of bits, which specifies offset
	in bit and number of bits within the address range specified by
	reg property. Offset takes values from 0-7.

Both 'map' and 'bits' combined already make a quite confusing binding.

Still it's easy to think of situations where this is still not enough.
Think of checksums or things like "The MAC is valid when this bit is
set" or the case you mention above when only the lower bytes of the MAC
address are stored in the nvmem. I think in all these situations a
purely descriptive binding is not enough.

Sascha

-- 
Pengutronix e.K.                           |                             |
Industrial Linux Solutions                 | http://www.pengutronix.de/  |
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