From 23fa18eaa71266feff7ba8d83022d9e1cc83c65a Mon Sep 17 00:00:00 2001
From: hc <hc@nodka.com>
Date: Fri, 10 May 2024 07:42:03 +0000
Subject: [PATCH] disable pwm7

---
 kernel/drivers/nvmem/core.c |  729 +++++++++++++++++++++++++++++++++++++++++++++----------
 1 files changed, 595 insertions(+), 134 deletions(-)

diff --git a/kernel/drivers/nvmem/core.c b/kernel/drivers/nvmem/core.c
index 9e4ba7a..b9a0326 100644
--- a/kernel/drivers/nvmem/core.c
+++ b/kernel/drivers/nvmem/core.c
@@ -1,17 +1,9 @@
+// SPDX-License-Identifier: GPL-2.0
 /*
  * 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 <linux/device.h>
@@ -23,10 +15,34 @@
 #include <linux/module.h>
 #include <linux/nvmem-consumer.h>
 #include <linux/nvmem-provider.h>
+#include <linux/gpio/consumer.h>
 #include <linux/of.h>
 #include <linux/slab.h>
 
-#include "nvmem.h"
+struct nvmem_device {
+	struct module		*owner;
+	struct device		dev;
+	int			stride;
+	int			word_size;
+	int			id;
+	struct kref		refcnt;
+	size_t			size;
+	bool			read_only;
+	bool			root_only;
+	int			flags;
+	enum nvmem_type		type;
+	struct bin_attribute	eeprom;
+	struct device		*base_dev;
+	struct list_head	cells;
+	nvmem_reg_read_t	reg_read;
+	nvmem_reg_write_t	reg_write;
+	struct gpio_desc	*wp_gpio;
+	void *priv;
+};
+
+#define to_nvmem_device(d) container_of(d, struct nvmem_device, dev)
+
+#define FLAG_COMPAT		BIT(0)
 
 struct nvmem_cell {
 	const char		*name;
@@ -45,6 +61,11 @@
 static DEFINE_MUTEX(nvmem_cell_mutex);
 static LIST_HEAD(nvmem_cell_tables);
 
+static DEFINE_MUTEX(nvmem_lookup_mutex);
+static LIST_HEAD(nvmem_lookup_list);
+
+static BLOCKING_NOTIFIER_HEAD(nvmem_notifier);
+
 static int nvmem_reg_read(struct nvmem_device *nvmem, unsigned int offset,
 			  void *val, size_t bytes)
 {
@@ -57,17 +78,253 @@
 static int nvmem_reg_write(struct nvmem_device *nvmem, unsigned int offset,
 			   void *val, size_t bytes)
 {
-	if (nvmem->reg_write)
-		return nvmem->reg_write(nvmem->priv, offset, val, bytes);
+	int ret;
+
+	if (nvmem->reg_write) {
+		gpiod_set_value_cansleep(nvmem->wp_gpio, 0);
+		ret = nvmem->reg_write(nvmem->priv, offset, val, bytes);
+		gpiod_set_value_cansleep(nvmem->wp_gpio, 1);
+		return ret;
+	}
 
 	return -EINVAL;
 }
+
+#ifdef CONFIG_NVMEM_SYSFS
+static const char * const nvmem_type_str[] = {
+	[NVMEM_TYPE_UNKNOWN] = "Unknown",
+	[NVMEM_TYPE_EEPROM] = "EEPROM",
+	[NVMEM_TYPE_OTP] = "OTP",
+	[NVMEM_TYPE_BATTERY_BACKED] = "Battery backed",
+};
+
+#ifdef CONFIG_DEBUG_LOCK_ALLOC
+static struct lock_class_key eeprom_lock_key;
+#endif
+
+static ssize_t type_show(struct device *dev,
+			 struct device_attribute *attr, char *buf)
+{
+	struct nvmem_device *nvmem = to_nvmem_device(dev);
+
+	return sprintf(buf, "%s\n", nvmem_type_str[nvmem->type]);
+}
+
+static DEVICE_ATTR_RO(type);
+
+static struct attribute *nvmem_attrs[] = {
+	&dev_attr_type.attr,
+	NULL,
+};
+
+static ssize_t bin_attr_nvmem_read(struct file *filp, struct kobject *kobj,
+				   struct bin_attribute *attr, char *buf,
+				   loff_t pos, size_t count)
+{
+	struct device *dev;
+	struct nvmem_device *nvmem;
+	int rc;
+
+	if (attr->private)
+		dev = attr->private;
+	else
+		dev = kobj_to_dev(kobj);
+	nvmem = to_nvmem_device(dev);
+
+	/* Stop the user from reading */
+	if (pos >= nvmem->size)
+		return 0;
+
+	if (!IS_ALIGNED(pos, nvmem->stride))
+		return -EINVAL;
+
+	if (count < nvmem->word_size)
+		return -EINVAL;
+
+	if (pos + count > nvmem->size)
+		count = nvmem->size - pos;
+
+	count = round_down(count, nvmem->word_size);
+
+	if (!nvmem->reg_read)
+		return -EPERM;
+
+	rc = nvmem_reg_read(nvmem, pos, buf, count);
+
+	if (rc)
+		return rc;
+
+	return count;
+}
+
+static ssize_t bin_attr_nvmem_write(struct file *filp, struct kobject *kobj,
+				    struct bin_attribute *attr, char *buf,
+				    loff_t pos, size_t count)
+{
+	struct device *dev;
+	struct nvmem_device *nvmem;
+	int rc;
+
+	if (attr->private)
+		dev = attr->private;
+	else
+		dev = kobj_to_dev(kobj);
+	nvmem = to_nvmem_device(dev);
+
+	/* Stop the user from writing */
+	if (pos >= nvmem->size)
+		return -EFBIG;
+
+	if (!IS_ALIGNED(pos, nvmem->stride))
+		return -EINVAL;
+
+	if (count < nvmem->word_size)
+		return -EINVAL;
+
+	if (pos + count > nvmem->size)
+		count = nvmem->size - pos;
+
+	count = round_down(count, nvmem->word_size);
+
+	if (!nvmem->reg_write)
+		return -EPERM;
+
+	rc = nvmem_reg_write(nvmem, pos, buf, count);
+
+	if (rc)
+		return rc;
+
+	return count;
+}
+
+static umode_t nvmem_bin_attr_get_umode(struct nvmem_device *nvmem)
+{
+	umode_t mode = 0400;
+
+	if (!nvmem->root_only)
+		mode |= 0044;
+
+	if (!nvmem->read_only)
+		mode |= 0200;
+
+	if (!nvmem->reg_write)
+		mode &= ~0200;
+
+	if (!nvmem->reg_read)
+		mode &= ~0444;
+
+	return mode;
+}
+
+static umode_t nvmem_bin_attr_is_visible(struct kobject *kobj,
+					 struct bin_attribute *attr, int i)
+{
+	struct device *dev = kobj_to_dev(kobj);
+	struct nvmem_device *nvmem = to_nvmem_device(dev);
+
+	attr->size = nvmem->size;
+
+	return nvmem_bin_attr_get_umode(nvmem);
+}
+
+/* default read/write permissions */
+static struct bin_attribute bin_attr_rw_nvmem = {
+	.attr	= {
+		.name	= "nvmem",
+		.mode	= 0644,
+	},
+	.read	= bin_attr_nvmem_read,
+	.write	= bin_attr_nvmem_write,
+};
+
+static struct bin_attribute *nvmem_bin_attributes[] = {
+	&bin_attr_rw_nvmem,
+	NULL,
+};
+
+static const struct attribute_group nvmem_bin_group = {
+	.bin_attrs	= nvmem_bin_attributes,
+	.attrs		= nvmem_attrs,
+	.is_bin_visible = nvmem_bin_attr_is_visible,
+};
+
+static const struct attribute_group *nvmem_dev_groups[] = {
+	&nvmem_bin_group,
+	NULL,
+};
+
+static struct bin_attribute bin_attr_nvmem_eeprom_compat = {
+	.attr	= {
+		.name	= "eeprom",
+	},
+	.read	= bin_attr_nvmem_read,
+	.write	= bin_attr_nvmem_write,
+};
+
+/*
+ * nvmem_setup_compat() - Create an additional binary entry in
+ * drivers sys directory, to be backwards compatible with the older
+ * drivers/misc/eeprom drivers.
+ */
+static int nvmem_sysfs_setup_compat(struct nvmem_device *nvmem,
+				    const struct nvmem_config *config)
+{
+	int rval;
+
+	if (!config->compat)
+		return 0;
+
+	if (!config->base_dev)
+		return -EINVAL;
+
+	nvmem->eeprom = bin_attr_nvmem_eeprom_compat;
+	nvmem->eeprom.attr.mode = nvmem_bin_attr_get_umode(nvmem);
+	nvmem->eeprom.size = nvmem->size;
+#ifdef CONFIG_DEBUG_LOCK_ALLOC
+	nvmem->eeprom.attr.key = &eeprom_lock_key;
+#endif
+	nvmem->eeprom.private = &nvmem->dev;
+	nvmem->base_dev = config->base_dev;
+
+	rval = device_create_bin_file(nvmem->base_dev, &nvmem->eeprom);
+	if (rval) {
+		dev_err(&nvmem->dev,
+			"Failed to create eeprom binary file %d\n", rval);
+		return rval;
+	}
+
+	nvmem->flags |= FLAG_COMPAT;
+
+	return 0;
+}
+
+static void nvmem_sysfs_remove_compat(struct nvmem_device *nvmem,
+			      const struct nvmem_config *config)
+{
+	if (config->compat)
+		device_remove_bin_file(nvmem->base_dev, &nvmem->eeprom);
+}
+
+#else /* CONFIG_NVMEM_SYSFS */
+
+static int nvmem_sysfs_setup_compat(struct nvmem_device *nvmem,
+				    const struct nvmem_config *config)
+{
+	return -ENOSYS;
+}
+static void nvmem_sysfs_remove_compat(struct nvmem_device *nvmem,
+				      const struct nvmem_config *config)
+{
+}
+
+#endif /* CONFIG_NVMEM_SYSFS */
 
 static void nvmem_release(struct device *dev)
 {
 	struct nvmem_device *nvmem = to_nvmem_device(dev);
 
-	ida_simple_remove(&nvmem_ida, nvmem->id);
+	ida_free(&nvmem_ida, nvmem->id);
+	gpiod_put(nvmem->wp_gpio);
 	kfree(nvmem);
 }
 
@@ -79,32 +336,14 @@
 	.name		= "nvmem",
 };
 
-static int of_nvmem_match(struct device *dev, void *nvmem_np)
-{
-	return dev->of_node == nvmem_np;
-}
-
-static struct nvmem_device *of_nvmem_find(struct device_node *nvmem_np)
-{
-	struct device *d;
-
-	if (!nvmem_np)
-		return NULL;
-
-	d = bus_find_device(&nvmem_bus_type, NULL, nvmem_np, of_nvmem_match);
-
-	if (!d)
-		return NULL;
-
-	return to_nvmem_device(d);
-}
-
 static void nvmem_cell_drop(struct nvmem_cell *cell)
 {
+	blocking_notifier_call_chain(&nvmem_notifier, NVMEM_CELL_REMOVE, cell);
 	mutex_lock(&nvmem_mutex);
 	list_del(&cell->node);
 	mutex_unlock(&nvmem_mutex);
 	of_node_put(cell->np);
+	kfree_const(cell->name);
 	kfree(cell);
 }
 
@@ -121,11 +360,12 @@
 	mutex_lock(&nvmem_mutex);
 	list_add_tail(&cell->node, &cell->nvmem->cells);
 	mutex_unlock(&nvmem_mutex);
+	blocking_notifier_call_chain(&nvmem_notifier, NVMEM_CELL_ADD, cell);
 }
 
-static int nvmem_cell_info_to_nvmem_cell(struct nvmem_device *nvmem,
-				   const struct nvmem_cell_info *info,
-				   struct nvmem_cell *cell)
+static int nvmem_cell_info_to_nvmem_cell_nodup(struct nvmem_device *nvmem,
+					const struct nvmem_cell_info *info,
+					struct nvmem_cell *cell)
 {
 	cell->nvmem = nvmem;
 	cell->offset = info->offset;
@@ -142,9 +382,26 @@
 	if (!IS_ALIGNED(cell->offset, nvmem->stride)) {
 		dev_err(&nvmem->dev,
 			"cell %s unaligned to nvmem stride %d\n",
-			cell->name, nvmem->stride);
+			cell->name ?: "<unknown>", nvmem->stride);
 		return -EINVAL;
 	}
+
+	return 0;
+}
+
+static int nvmem_cell_info_to_nvmem_cell(struct nvmem_device *nvmem,
+				const struct nvmem_cell_info *info,
+				struct nvmem_cell *cell)
+{
+	int err;
+
+	err = nvmem_cell_info_to_nvmem_cell_nodup(nvmem, info, cell);
+	if (err)
+		return err;
+
+	cell->name = kstrdup_const(info->name, GFP_KERNEL);
+	if (!cell->name)
+		return -ENOMEM;
 
 	return 0;
 }
@@ -158,7 +415,7 @@
  *
  * Return: 0 or negative error code on failure.
  */
-int nvmem_add_cells(struct nvmem_device *nvmem,
+static int nvmem_add_cells(struct nvmem_device *nvmem,
 		    const struct nvmem_cell_info *info,
 		    int ncells)
 {
@@ -197,7 +454,32 @@
 
 	return rval;
 }
-EXPORT_SYMBOL_GPL(nvmem_add_cells);
+
+/**
+ * nvmem_register_notifier() - Register a notifier block for nvmem events.
+ *
+ * @nb: notifier block to be called on nvmem events.
+ *
+ * Return: 0 on success, negative error number on failure.
+ */
+int nvmem_register_notifier(struct notifier_block *nb)
+{
+	return blocking_notifier_chain_register(&nvmem_notifier, nb);
+}
+EXPORT_SYMBOL_GPL(nvmem_register_notifier);
+
+/**
+ * nvmem_unregister_notifier() - Unregister a notifier block for nvmem events.
+ *
+ * @nb: notifier block to be unregistered.
+ *
+ * Return: 0 on success, negative error number on failure.
+ */
+int nvmem_unregister_notifier(struct notifier_block *nb)
+{
+	return blocking_notifier_chain_unregister(&nvmem_notifier, nb);
+}
+EXPORT_SYMBOL_GPL(nvmem_unregister_notifier);
 
 static int nvmem_add_cells_from_table(struct nvmem_device *nvmem)
 {
@@ -236,6 +518,23 @@
 	return rval;
 }
 
+static struct nvmem_cell *
+nvmem_find_cell_by_name(struct nvmem_device *nvmem, const char *cell_id)
+{
+	struct nvmem_cell *iter, *cell = NULL;
+
+	mutex_lock(&nvmem_mutex);
+	list_for_each_entry(iter, &nvmem->cells, node) {
+		if (strcmp(cell_id, iter->name) == 0) {
+			cell = iter;
+			break;
+		}
+	}
+	mutex_unlock(&nvmem_mutex);
+
+	return cell;
+}
+
 static int nvmem_add_cells_from_of(struct nvmem_device *nvmem)
 {
 	struct device_node *parent, *child;
@@ -248,20 +547,24 @@
 
 	for_each_child_of_node(parent, child) {
 		addr = of_get_property(child, "reg", &len);
-		if (!addr || (len < 2 * sizeof(u32))) {
+		if (!addr)
+			continue;
+		if (len < 2 * sizeof(u32)) {
 			dev_err(dev, "nvmem: invalid reg on %pOF\n", child);
+			of_node_put(child);
 			return -EINVAL;
 		}
 
 		cell = kzalloc(sizeof(*cell), GFP_KERNEL);
-		if (!cell)
+		if (!cell) {
+			of_node_put(child);
 			return -ENOMEM;
+		}
 
 		cell->nvmem = nvmem;
-		cell->np = of_node_get(child);
 		cell->offset = be32_to_cpup(addr++);
 		cell->bytes = be32_to_cpup(addr);
-		cell->name = child->name;
+		cell->name = kasprintf(GFP_KERNEL, "%pOFn", child);
 
 		addr = of_get_property(child, "bits", &len);
 		if (addr && len == (2 * sizeof(u32))) {
@@ -278,10 +581,13 @@
 			dev_err(dev, "cell %s unaligned to nvmem stride %d\n",
 				cell->name, nvmem->stride);
 			/* Cells already added will be freed later. */
+			kfree_const(cell->name);
 			kfree(cell);
+			of_node_put(child);
 			return -EINVAL;
 		}
 
+		cell->np = of_node_get(child);
 		nvmem_cell_add(cell);
 	}
 
@@ -290,7 +596,7 @@
 
 /**
  * nvmem_register() - Register a nvmem device for given nvmem_config.
- * Also creates an binary entry in /sys/bus/nvmem/devices/dev-name/nvmem
+ * Also creates a binary entry in /sys/bus/nvmem/devices/dev-name/nvmem
  *
  * @config: nvmem device configuration with which nvmem device is created.
  *
@@ -306,12 +612,29 @@
 	if (!config->dev)
 		return ERR_PTR(-EINVAL);
 
+	if (!config->reg_read && !config->reg_write)
+		return ERR_PTR(-EINVAL);
+
 	nvmem = kzalloc(sizeof(*nvmem), GFP_KERNEL);
 	if (!nvmem)
 		return ERR_PTR(-ENOMEM);
 
-	rval  = ida_simple_get(&nvmem_ida, 0, 0, GFP_KERNEL);
+	rval  = ida_alloc(&nvmem_ida, GFP_KERNEL);
 	if (rval < 0) {
+		kfree(nvmem);
+		return ERR_PTR(rval);
+	}
+
+	nvmem->id = rval;
+
+	if (config->wp_gpio)
+		nvmem->wp_gpio = config->wp_gpio;
+	else
+		nvmem->wp_gpio = gpiod_get_optional(config->dev, "wp",
+						    GPIOD_OUT_HIGH);
+	if (IS_ERR(nvmem->wp_gpio)) {
+		ida_free(&nvmem_ida, nvmem->id);
+		rval = PTR_ERR(nvmem->wp_gpio);
 		kfree(nvmem);
 		return ERR_PTR(rval);
 	}
@@ -319,7 +642,6 @@
 	kref_init(&nvmem->refcnt);
 	INIT_LIST_HEAD(&nvmem->cells);
 
-	nvmem->id = rval;
 	nvmem->owner = config->owner;
 	if (!nvmem->owner && config->dev->driver)
 		nvmem->owner = config->dev->driver->owner;
@@ -329,29 +651,44 @@
 	nvmem->dev.type = &nvmem_provider_type;
 	nvmem->dev.bus = &nvmem_bus_type;
 	nvmem->dev.parent = config->dev;
+	nvmem->root_only = config->root_only;
 	nvmem->priv = config->priv;
+	nvmem->type = config->type;
 	nvmem->reg_read = config->reg_read;
 	nvmem->reg_write = config->reg_write;
-	nvmem->dev.of_node = config->dev->of_node;
+	if (!config->no_of_node)
+		nvmem->dev.of_node = config->dev->of_node;
 
-	if (config->id == -1 && config->name) {
-		dev_set_name(&nvmem->dev, "%s", config->name);
-	} else {
-		dev_set_name(&nvmem->dev, "%s%d",
+	switch (config->id) {
+	case NVMEM_DEVID_NONE:
+		rval = dev_set_name(&nvmem->dev, "%s", config->name);
+		break;
+	case NVMEM_DEVID_AUTO:
+		rval = dev_set_name(&nvmem->dev, "%s%d", config->name, nvmem->id);
+		break;
+	default:
+		rval = dev_set_name(&nvmem->dev, "%s%d",
 			     config->name ? : "nvmem",
 			     config->name ? config->id : nvmem->id);
+		break;
 	}
 
-	nvmem->read_only = device_property_present(config->dev, "read-only") |
-			   config->read_only;
+	if (rval) {
+		ida_free(&nvmem_ida, nvmem->id);
+		kfree(nvmem);
+		return ERR_PTR(rval);
+	}
 
-	nvmem->dev.groups = nvmem_sysfs_get_groups(nvmem, config);
+	nvmem->read_only = device_property_present(config->dev, "read-only") ||
+			   config->read_only || !nvmem->reg_write;
 
-	device_initialize(&nvmem->dev);
+#ifdef CONFIG_NVMEM_SYSFS
+	nvmem->dev.groups = nvmem_dev_groups;
+#endif
 
 	dev_dbg(&nvmem->dev, "Registering nvmem device %s\n", config->name);
 
-	rval = device_add(&nvmem->dev);
+	rval = device_register(&nvmem->dev);
 	if (rval)
 		goto err_put_device;
 
@@ -364,7 +701,7 @@
 	if (config->cells) {
 		rval = nvmem_add_cells(nvmem, config->cells, config->ncells);
 		if (rval)
-			goto err_teardown_compat;
+			goto err_remove_cells;
 	}
 
 	rval = nvmem_add_cells_from_table(nvmem);
@@ -375,11 +712,12 @@
 	if (rval)
 		goto err_remove_cells;
 
+	blocking_notifier_call_chain(&nvmem_notifier, NVMEM_ADD, nvmem);
+
 	return nvmem;
 
 err_remove_cells:
 	nvmem_device_remove_all_cells(nvmem);
-err_teardown_compat:
 	if (config->compat)
 		nvmem_sysfs_remove_compat(nvmem, config);
 err_device_del:
@@ -397,38 +735,35 @@
 
 	nvmem = container_of(kref, struct nvmem_device, refcnt);
 
+	blocking_notifier_call_chain(&nvmem_notifier, NVMEM_REMOVE, nvmem);
+
 	if (nvmem->flags & FLAG_COMPAT)
 		device_remove_bin_file(nvmem->base_dev, &nvmem->eeprom);
 
 	nvmem_device_remove_all_cells(nvmem);
-	device_del(&nvmem->dev);
-	put_device(&nvmem->dev);
+	device_unregister(&nvmem->dev);
 }
 
 /**
  * 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)
+void nvmem_unregister(struct nvmem_device *nvmem)
 {
 	kref_put(&nvmem->refcnt, nvmem_device_release);
-
-	return 0;
 }
 EXPORT_SYMBOL_GPL(nvmem_unregister);
 
 static void devm_nvmem_release(struct device *dev, void *res)
 {
-	WARN_ON(nvmem_unregister(*(struct nvmem_device **)res));
+	nvmem_unregister(*(struct nvmem_device **)res);
 }
 
 /**
  * devm_nvmem_register() - Register a managed nvmem device for given
  * nvmem_config.
- * Also creates an binary entry in /sys/bus/nvmem/devices/dev-name/nvmem
+ * Also creates a binary entry in /sys/bus/nvmem/devices/dev-name/nvmem
  *
  * @dev: Device that uses the nvmem device.
  * @config: nvmem device configuration with which nvmem device is created.
@@ -472,7 +807,7 @@
  * @dev: Device that uses the nvmem device.
  * @nvmem: Pointer to previously registered nvmem device.
  *
- * Return: Will be an negative on error or a zero on success.
+ * Return: Will be negative on error or zero on success.
  */
 int devm_nvmem_unregister(struct device *dev, struct nvmem_device *nvmem)
 {
@@ -480,18 +815,16 @@
 }
 EXPORT_SYMBOL(devm_nvmem_unregister);
 
-
-static struct nvmem_device *__nvmem_device_get(struct device_node *np,
-					       struct nvmem_cell **cellp,
-					       const char *cell_id)
+static struct nvmem_device *__nvmem_device_get(void *data,
+			int (*match)(struct device *dev, const void *data))
 {
 	struct nvmem_device *nvmem = NULL;
-
-	if (!np)
-		return ERR_PTR(-ENOENT);
+	struct device *dev;
 
 	mutex_lock(&nvmem_mutex);
-	nvmem = of_nvmem_find(np);
+	dev = bus_find_device(&nvmem_bus_type, NULL, data, match);
+	if (dev)
+		nvmem = to_nvmem_device(dev);
 	mutex_unlock(&nvmem_mutex);
 	if (!nvmem)
 		return ERR_PTR(-EPROBE_DEFER);
@@ -499,8 +832,9 @@
 	if (!try_module_get(nvmem->owner)) {
 		dev_err(&nvmem->dev,
 			"could not increase module refcount for cell %s\n",
-			nvmem->name);
+			nvmem_dev_name(nvmem));
 
+		put_device(&nvmem->dev);
 		return ERR_PTR(-EINVAL);
 	}
 
@@ -511,20 +845,9 @@
 
 static void __nvmem_device_put(struct nvmem_device *nvmem)
 {
+	put_device(&nvmem->dev);
 	module_put(nvmem->owner);
 	kref_put(&nvmem->refcnt, nvmem_device_release);
-}
-
-static struct nvmem_device *nvmem_find(const char *name)
-{
-	struct device *d;
-
-	d = bus_find_device_by_name(&nvmem_bus_type, NULL, name);
-
-	if (!d)
-		return ERR_PTR(-ENOENT);
-
-	return to_nvmem_device(d);
 }
 
 #if IS_ENABLED(CONFIG_OF)
@@ -541,15 +864,19 @@
 {
 
 	struct device_node *nvmem_np;
-	int index;
+	struct nvmem_device *nvmem;
+	int index = 0;
 
-	index = of_property_match_string(np, "nvmem-names", id);
+	if (id)
+		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 ERR_PTR(-ENOENT);
 
-	return __nvmem_device_get(nvmem_np, NULL, NULL);
+	nvmem = __nvmem_device_get(nvmem_np, device_match_of_node);
+	of_node_put(nvmem_np);
+	return nvmem;
 }
 EXPORT_SYMBOL_GPL(of_nvmem_device_get);
 #endif
@@ -575,9 +902,25 @@
 
 	}
 
-	return nvmem_find(dev_name);
+	return __nvmem_device_get((void *)dev_name, device_match_name);
 }
 EXPORT_SYMBOL_GPL(nvmem_device_get);
+
+/**
+ * nvmem_device_find() - Find nvmem device with matching function
+ *
+ * @data: Data to pass to match function
+ * @match: Callback function to check device
+ *
+ * Return: ERR_PTR() on error or a valid pointer to a struct nvmem_device
+ * on success.
+ */
+struct nvmem_device *nvmem_device_find(void *data,
+			int (*match)(struct device *dev, const void *data))
+{
+	return __nvmem_device_get(data, match);
+}
+EXPORT_SYMBOL_GPL(nvmem_device_find);
 
 static int devm_nvmem_device_match(struct device *dev, void *res, void *data)
 {
@@ -653,15 +996,44 @@
 }
 EXPORT_SYMBOL_GPL(devm_nvmem_device_get);
 
-static struct nvmem_cell *nvmem_cell_get_from_list(const char *cell_id)
+static struct nvmem_cell *
+nvmem_cell_get_from_lookup(struct device *dev, const char *con_id)
 {
-	struct nvmem_cell *cell = NULL;
+	struct nvmem_cell *cell = ERR_PTR(-ENOENT);
+	struct nvmem_cell_lookup *lookup;
 	struct nvmem_device *nvmem;
+	const char *dev_id;
 
-	nvmem = __nvmem_device_get(NULL, &cell, cell_id);
-	if (IS_ERR(nvmem))
-		return ERR_CAST(nvmem);
+	if (!dev)
+		return ERR_PTR(-EINVAL);
 
+	dev_id = dev_name(dev);
+
+	mutex_lock(&nvmem_lookup_mutex);
+
+	list_for_each_entry(lookup, &nvmem_lookup_list, node) {
+		if ((strcmp(lookup->dev_id, dev_id) == 0) &&
+		    (strcmp(lookup->con_id, con_id) == 0)) {
+			/* This is the right entry. */
+			nvmem = __nvmem_device_get((void *)lookup->nvmem_name,
+						   device_match_name);
+			if (IS_ERR(nvmem)) {
+				/* Provider may not be registered yet. */
+				cell = ERR_CAST(nvmem);
+				break;
+			}
+
+			cell = nvmem_find_cell_by_name(nvmem,
+						       lookup->cell_name);
+			if (!cell) {
+				__nvmem_device_put(nvmem);
+				cell = ERR_PTR(-ENOENT);
+			}
+			break;
+		}
+	}
+
+	mutex_unlock(&nvmem_lookup_mutex);
 	return cell;
 }
 
@@ -669,12 +1041,14 @@
 static struct nvmem_cell *
 nvmem_find_cell_by_node(struct nvmem_device *nvmem, struct device_node *np)
 {
-	struct nvmem_cell *cell = NULL;
+	struct nvmem_cell *iter, *cell = NULL;
 
 	mutex_lock(&nvmem_mutex);
-	list_for_each_entry(cell, &nvmem->cells, node) {
-		if (np == cell->np)
+	list_for_each_entry(iter, &nvmem->cells, node) {
+		if (np == iter->np) {
+			cell = iter;
 			break;
+		}
 	}
 	mutex_unlock(&nvmem_mutex);
 
@@ -685,16 +1059,15 @@
  * of_nvmem_cell_get() - Get a nvmem cell from given device node and cell id
  *
  * @np: Device tree node that uses the nvmem cell.
- * @name: nvmem cell name from nvmem-cell-names property, or NULL
- *	  for the cell at index 0 (the lone cell with no accompanying
- *	  nvmem-cell-names property).
+ * @id: nvmem cell name from nvmem-cell-names property, or NULL
+ *      for the cell at index 0 (the lone cell with no accompanying
+ *      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 nvmem_cell *of_nvmem_cell_get(struct device_node *np, const char *id)
 {
 	struct device_node *cell_np, *nvmem_np;
 	struct nvmem_device *nvmem;
@@ -702,18 +1075,18 @@
 	int index = 0;
 
 	/* if cell name exists, find index to the name */
-	if (name)
-		index = of_property_match_string(np, "nvmem-cell-names", name);
+	if (id)
+		index = of_property_match_string(np, "nvmem-cell-names", id);
 
 	cell_np = of_parse_phandle(np, "nvmem-cells", index);
 	if (!cell_np)
-		return ERR_PTR(-EINVAL);
+		return ERR_PTR(-ENOENT);
 
 	nvmem_np = of_get_next_parent(cell_np);
 	if (!nvmem_np)
 		return ERR_PTR(-EINVAL);
 
-	nvmem = __nvmem_device_get(nvmem_np, NULL, NULL);
+	nvmem = __nvmem_device_get(nvmem_np, device_match_of_node);
 	of_node_put(nvmem_np);
 	if (IS_ERR(nvmem))
 		return ERR_CAST(nvmem);
@@ -733,27 +1106,29 @@
  * nvmem_cell_get() - Get nvmem cell of device form a given cell name
  *
  * @dev: Device that requests the nvmem cell.
- * @cell_id: nvmem cell name to get.
+ * @id: nvmem cell name to get (this corresponds with the name from the
+ *      nvmem-cell-names property for DT systems and with the con_id from
+ *      the lookup entry for non-DT systems).
  *
  * 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 *dev, const char *cell_id)
+struct nvmem_cell *nvmem_cell_get(struct device *dev, const char *id)
 {
 	struct nvmem_cell *cell;
 
 	if (dev->of_node) { /* try dt first */
-		cell = of_nvmem_cell_get(dev->of_node, cell_id);
+		cell = of_nvmem_cell_get(dev->of_node, id);
 		if (!IS_ERR(cell) || PTR_ERR(cell) == -EPROBE_DEFER)
 			return cell;
 	}
 
-	/* NULL cell_id only allowed for device tree; invalid otherwise */
-	if (!cell_id)
+	/* NULL cell id only allowed for device tree; invalid otherwise */
+	if (!id)
 		return ERR_PTR(-EINVAL);
 
-	return nvmem_cell_get_from_list(cell_id);
+	return nvmem_cell_get_from_lookup(dev, id);
 }
 EXPORT_SYMBOL_GPL(nvmem_cell_get);
 
@@ -1010,16 +1385,8 @@
 }
 EXPORT_SYMBOL_GPL(nvmem_cell_write);
 
-/**
- * nvmem_cell_read_u32() - Read a cell value as an u32
- *
- * @dev: Device that requests the nvmem cell.
- * @cell_id: Name of nvmem cell to read.
- * @val: pointer to output value.
- *
- * Return: 0 on success or negative errno.
- */
-int nvmem_cell_read_u32(struct device *dev, const char *cell_id, u32 *val)
+static int nvmem_cell_read_common(struct device *dev, const char *cell_id,
+				  void *val, size_t count)
 {
 	struct nvmem_cell *cell;
 	void *buf;
@@ -1034,18 +1401,77 @@
 		nvmem_cell_put(cell);
 		return PTR_ERR(buf);
 	}
-	if (len != sizeof(*val)) {
+	if (len != count) {
 		kfree(buf);
 		nvmem_cell_put(cell);
 		return -EINVAL;
 	}
-	memcpy(val, buf, sizeof(*val));
-
+	memcpy(val, buf, count);
 	kfree(buf);
 	nvmem_cell_put(cell);
+
 	return 0;
 }
+
+/**
+ * nvmem_cell_read_u8() - Read a cell value as a u8
+ *
+ * @dev: Device that requests the nvmem cell.
+ * @cell_id: Name of nvmem cell to read.
+ * @val: pointer to output value.
+ *
+ * Return: 0 on success or negative errno.
+ */
+int nvmem_cell_read_u8(struct device *dev, const char *cell_id, u8 *val)
+{
+	return nvmem_cell_read_common(dev, cell_id, val, sizeof(*val));
+}
+EXPORT_SYMBOL_GPL(nvmem_cell_read_u8);
+
+/**
+ * nvmem_cell_read_u16() - Read a cell value as a u16
+ *
+ * @dev: Device that requests the nvmem cell.
+ * @cell_id: Name of nvmem cell to read.
+ * @val: pointer to output value.
+ *
+ * Return: 0 on success or negative errno.
+ */
+int nvmem_cell_read_u16(struct device *dev, const char *cell_id, u16 *val)
+{
+	return nvmem_cell_read_common(dev, cell_id, val, sizeof(*val));
+}
+EXPORT_SYMBOL_GPL(nvmem_cell_read_u16);
+
+/**
+ * nvmem_cell_read_u32() - Read a cell value as a u32
+ *
+ * @dev: Device that requests the nvmem cell.
+ * @cell_id: Name of nvmem cell to read.
+ * @val: pointer to output value.
+ *
+ * Return: 0 on success or negative errno.
+ */
+int nvmem_cell_read_u32(struct device *dev, const char *cell_id, u32 *val)
+{
+	return nvmem_cell_read_common(dev, cell_id, val, sizeof(*val));
+}
 EXPORT_SYMBOL_GPL(nvmem_cell_read_u32);
+
+/**
+ * nvmem_cell_read_u64() - Read a cell value as a u64
+ *
+ * @dev: Device that requests the nvmem cell.
+ * @cell_id: Name of nvmem cell to read.
+ * @val: pointer to output value.
+ *
+ * Return: 0 on success or negative errno.
+ */
+int nvmem_cell_read_u64(struct device *dev, const char *cell_id, u64 *val)
+{
+	return nvmem_cell_read_common(dev, cell_id, val, sizeof(*val));
+}
+EXPORT_SYMBOL_GPL(nvmem_cell_read_u64);
 
 /**
  * nvmem_device_cell_read() - Read a given nvmem device and cell
@@ -1067,7 +1493,7 @@
 	if (!nvmem)
 		return -EINVAL;
 
-	rc = nvmem_cell_info_to_nvmem_cell(nvmem, info, &cell);
+	rc = nvmem_cell_info_to_nvmem_cell_nodup(nvmem, info, &cell);
 	if (rc)
 		return rc;
 
@@ -1087,7 +1513,7 @@
  * @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)
 {
@@ -1097,7 +1523,7 @@
 	if (!nvmem)
 		return -EINVAL;
 
-	rc = nvmem_cell_info_to_nvmem_cell(nvmem, info, &cell);
+	rc = nvmem_cell_info_to_nvmem_cell_nodup(nvmem, info, &cell);
 	if (rc)
 		return rc;
 
@@ -1143,7 +1569,7 @@
  * @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)
@@ -1190,6 +1616,41 @@
 EXPORT_SYMBOL_GPL(nvmem_del_cell_table);
 
 /**
+ * nvmem_add_cell_lookups() - register a list of cell lookup entries
+ *
+ * @entries: array of cell lookup entries
+ * @nentries: number of cell lookup entries in the array
+ */
+void nvmem_add_cell_lookups(struct nvmem_cell_lookup *entries, size_t nentries)
+{
+	int i;
+
+	mutex_lock(&nvmem_lookup_mutex);
+	for (i = 0; i < nentries; i++)
+		list_add_tail(&entries[i].node, &nvmem_lookup_list);
+	mutex_unlock(&nvmem_lookup_mutex);
+}
+EXPORT_SYMBOL_GPL(nvmem_add_cell_lookups);
+
+/**
+ * nvmem_del_cell_lookups() - remove a list of previously added cell lookup
+ *                            entries
+ *
+ * @entries: array of cell lookup entries
+ * @nentries: number of cell lookup entries in the array
+ */
+void nvmem_del_cell_lookups(struct nvmem_cell_lookup *entries, size_t nentries)
+{
+	int i;
+
+	mutex_lock(&nvmem_lookup_mutex);
+	for (i = 0; i < nentries; i++)
+		list_del(&entries[i].node);
+	mutex_unlock(&nvmem_lookup_mutex);
+}
+EXPORT_SYMBOL_GPL(nvmem_del_cell_lookups);
+
+/**
  * nvmem_dev_name() - Get the name of a given nvmem device.
  *
  * @nvmem: nvmem device.

--
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