99 lines
2.4 KiB
C
99 lines
2.4 KiB
C
|
// SPDX-License-Identifier: GPL-2.0+
|
||
|
|
/*
|
||
|
|
* Copyright (C) 2020 Nicolas Saenz Julienne <nsaenzjulienne@suse.de>
|
||
|
|
*/
|
||
|
|
|
||
|
|
#include <linux/io.h>
|
||
|
|
#include <linux/module.h>
|
||
|
|
#include <linux/nvmem-provider.h>
|
||
|
|
#include <linux/of_reserved_mem.h>
|
||
|
|
#include <linux/platform_device.h>
|
||
|
|
|
||
|
|
struct rmem {
|
||
|
|
struct device *dev;
|
||
|
|
struct nvmem_device *nvmem;
|
||
|
|
struct reserved_mem *mem;
|
||
|
|
|
||
|
|
phys_addr_t size;
|
||
|
|
};
|
||
|
|
|
||
|
|
static int rmem_read(void *context, unsigned int offset,
|
||
|
|
void *val, size_t bytes)
|
||
|
|
{
|
||
|
|
struct rmem *priv = context;
|
||
|
|
size_t available = priv->mem->size;
|
||
|
|
loff_t off = offset;
|
||
|
|
void *addr;
|
||
|
|
int count;
|
||
|
|
|
||
|
|
/*
|
||
|
|
* Only map the reserved memory at this point to avoid potential rogue
|
||
|
|
* kernel threads inadvertently modifying it. Based on the current
|
||
|
|
* uses-cases for this driver, the performance hit isn't a concern.
|
||
|
|
* Nor is likely to be, given the nature of the subsystem. Most nvmem
|
||
|
|
* devices operate over slow buses to begin with.
|
||
|
|
*
|
||
|
|
* An alternative would be setting the memory as RO, set_memory_ro(),
|
||
|
|
* but as of Dec 2020 this isn't possible on arm64.
|
||
|
|
*/
|
||
|
|
addr = memremap(priv->mem->base, available, MEMREMAP_WB);
|
||
|
|
if (!addr) {
|
||
|
|
dev_err(priv->dev, "Failed to remap memory region\n");
|
||
|
|
return -ENOMEM;
|
||
|
|
}
|
||
|
|
|
||
|
|
count = memory_read_from_buffer(val, bytes, &off, addr, available);
|
||
|
|
|
||
|
|
memunmap(addr);
|
||
|
|
|
||
|
|
return count;
|
||
|
|
}
|
||
|
|
|
||
|
|
static int rmem_probe(struct platform_device *pdev)
|
||
|
|
{
|
||
|
|
struct nvmem_config config = { };
|
||
|
|
struct device *dev = &pdev->dev;
|
||
|
|
struct reserved_mem *mem;
|
||
|
|
struct rmem *priv;
|
||
|
|
|
||
|
|
priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
|
||
|
|
if (!priv)
|
||
|
|
return -ENOMEM;
|
||
|
|
priv->dev = dev;
|
||
|
|
|
||
|
|
mem = of_reserved_mem_lookup(dev->of_node);
|
||
|
|
if (!mem) {
|
||
|
|
dev_err(dev, "Failed to lookup reserved memory\n");
|
||
|
|
return -EINVAL;
|
||
|
|
}
|
||
|
|
priv->mem = mem;
|
||
|
|
|
||
|
|
config.dev = dev;
|
||
|
|
config.priv = priv;
|
||
|
|
config.name = "rmem";
|
||
|
|
config.id = NVMEM_DEVID_AUTO;
|
||
|
|
config.size = mem->size;
|
||
|
|
config.reg_read = rmem_read;
|
||
|
|
|
||
|
|
return PTR_ERR_OR_ZERO(devm_nvmem_register(dev, &config));
|
||
|
|
}
|
||
|
|
|
||
|
|
static const struct of_device_id rmem_match[] = {
|
||
|
|
{ .compatible = "nvmem-rmem", },
|
||
|
|
{ /* sentinel */ },
|
||
|
|
};
|
||
|
|
MODULE_DEVICE_TABLE(of, rmem_match);
|
||
|
|
|
||
|
|
static struct platform_driver rmem_driver = {
|
||
|
|
.probe = rmem_probe,
|
||
|
|
.driver = {
|
||
|
|
.name = "rmem",
|
||
|
|
.of_match_table = rmem_match,
|
||
|
|
},
|
||
|
|
};
|
||
|
|
module_platform_driver(rmem_driver);
|
||
|
|
|
||
|
|
MODULE_AUTHOR("Nicolas Saenz Julienne <nsaenzjulienne@suse.de>");
|
||
|
|
MODULE_DESCRIPTION("Reserved Memory Based nvmem Driver");
|
||
|
|
MODULE_LICENSE("GPL");
|