diff options
Diffstat (limited to 'drivers/nvmem/core.c')
-rw-r--r-- | drivers/nvmem/core.c | 406 |
1 files changed, 406 insertions, 0 deletions
diff --git a/drivers/nvmem/core.c b/drivers/nvmem/core.c new file mode 100644 index 000000000000..2b024915e224 --- /dev/null +++ b/drivers/nvmem/core.c @@ -0,0 +1,406 @@ +/* + * 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> +#include <linux/export.h> +#include <linux/fs.h> +#include <linux/idr.h> +#include <linux/init.h> +#include <linux/module.h> +#include <linux/nvmem-consumer.h> +#include <linux/nvmem-provider.h> +#include <linux/of.h> +#include <linux/regmap.h> +#include <linux/slab.h> + +struct nvmem_device { + const char *name; + struct regmap *regmap; + struct module *owner; + struct device dev; + int stride; + int word_size; + int ncells; + int id; + int users; + size_t size; + bool read_only; +}; + +struct nvmem_cell { + const char *name; + int offset; + int bytes; + int bit_offset; + int nbits; + struct nvmem_device *nvmem; + struct list_head node; +}; + +static DEFINE_MUTEX(nvmem_mutex); +static DEFINE_IDA(nvmem_ida); + +static LIST_HEAD(nvmem_cells); +static DEFINE_MUTEX(nvmem_cells_mutex); + +#define to_nvmem_device(d) container_of(d, struct nvmem_device, dev) + +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 = container_of(kobj, struct device, kobj); + struct nvmem_device *nvmem = to_nvmem_device(dev); + int rc; + + /* Stop the user from reading */ + if (pos > nvmem->size) + return 0; + + if (pos + count > nvmem->size) + count = nvmem->size - pos; + + count = round_down(count, nvmem->word_size); + + rc = regmap_raw_read(nvmem->regmap, pos, buf, count); + + if (IS_ERR_VALUE(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 = container_of(kobj, struct device, kobj); + struct nvmem_device *nvmem = to_nvmem_device(dev); + int rc; + + /* Stop the user from writing */ + if (pos > nvmem->size) + return 0; + + if (pos + count > nvmem->size) + count = nvmem->size - pos; + + count = round_down(count, nvmem->word_size); + + rc = regmap_raw_write(nvmem->regmap, pos, buf, count); + + if (IS_ERR_VALUE(rc)) + return rc; + + return count; +} + +/* default read/write permissions */ +static struct bin_attribute bin_attr_rw_nvmem = { + .attr = { + .name = "nvmem", + .mode = S_IWUSR | S_IRUGO, + }, + .read = bin_attr_nvmem_read, + .write = bin_attr_nvmem_write, +}; + +static struct bin_attribute *nvmem_bin_rw_attributes[] = { + &bin_attr_rw_nvmem, + NULL, +}; + +static const struct attribute_group nvmem_bin_rw_group = { + .bin_attrs = nvmem_bin_rw_attributes, +}; + +static const struct attribute_group *nvmem_rw_dev_groups[] = { + &nvmem_bin_rw_group, + NULL, +}; + +/* read only permission */ +static struct bin_attribute bin_attr_ro_nvmem = { + .attr = { + .name = "nvmem", + .mode = S_IRUGO, + }, + .read = bin_attr_nvmem_read, +}; + +static struct bin_attribute *nvmem_bin_ro_attributes[] = { + &bin_attr_ro_nvmem, + NULL, +}; + +static const struct attribute_group nvmem_bin_ro_group = { + .bin_attrs = nvmem_bin_ro_attributes, +}; + +static const struct attribute_group *nvmem_ro_dev_groups[] = { + &nvmem_bin_ro_group, + NULL, +}; + +static void nvmem_release(struct device *dev) +{ + struct nvmem_device *nvmem = to_nvmem_device(dev); + + ida_simple_remove(&nvmem_ida, nvmem->id); + kfree(nvmem); +} + +static const struct device_type nvmem_provider_type = { + .release = nvmem_release, +}; + +static struct bus_type nvmem_bus_type = { + .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 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) +{ + mutex_lock(&nvmem_cells_mutex); + list_del(&cell->node); + mutex_unlock(&nvmem_cells_mutex); + 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) +{ + mutex_lock(&nvmem_cells_mutex); + list_add_tail(&cell->node, &nvmem_cells); + mutex_unlock(&nvmem_cells_mutex); +} + +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 = kcalloc(cfg->ncells, sizeof(*cells), 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. + * Also creates an binary entry in /sys/bus/nvmem/devices/dev-name/nvmem + * + * @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; + struct regmap *rm; + int rval; + + if (!config->dev) + return ERR_PTR(-EINVAL); + + rm = dev_get_regmap(config->dev, NULL); + if (!rm) { + dev_err(config->dev, "Regmap not found\n"); + 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); + if (rval < 0) { + kfree(nvmem); + return ERR_PTR(rval); + } + + nvmem->id = rval; + nvmem->regmap = rm; + nvmem->owner = config->owner; + nvmem->stride = regmap_get_reg_stride(rm); + nvmem->word_size = regmap_get_val_bytes(rm); + nvmem->size = regmap_get_max_register(rm) + nvmem->stride; + nvmem->dev.type = &nvmem_provider_type; + nvmem->dev.bus = &nvmem_bus_type; + nvmem->dev.parent = config->dev; + np = config->dev->of_node; + nvmem->dev.of_node = np; + dev_set_name(&nvmem->dev, "%s%d", + config->name ? : "nvmem", config->id); + + nvmem->read_only = of_property_read_bool(np, "read-only") | + config->read_only; + + nvmem->dev.groups = nvmem->read_only ? nvmem_ro_dev_groups : + nvmem_rw_dev_groups; + + device_initialize(&nvmem->dev); + + dev_dbg(&nvmem->dev, "Registering nvmem device %s\n", config->name); + + rval = device_add(&nvmem->dev); + if (rval) { + ida_simple_remove(&nvmem_ida, nvmem->id); + kfree(nvmem); + return ERR_PTR(rval); + } + + 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); + device_del(&nvmem->dev); + + return 0; +} +EXPORT_SYMBOL_GPL(nvmem_unregister); + +static int __init nvmem_init(void) +{ + return bus_register(&nvmem_bus_type); +} + +static void __exit nvmem_exit(void) +{ + bus_unregister(&nvmem_bus_type); +} + +subsys_initcall(nvmem_init); +module_exit(nvmem_exit); + +MODULE_AUTHOR("Srinivas Kandagatla <srinivas.kandagatla@linaro.org"); +MODULE_AUTHOR("Maxime Ripard <maxime.ripard@free-electrons.com"); +MODULE_DESCRIPTION("nvmem Driver Core"); +MODULE_LICENSE("GPL v2"); |