nvmem-reboot-mode.c

 1// SPDX-License-Identifier: GPL-2.0+
 2/*
 3 * Copyright (c) Vaisala Oyj. All rights reserved.
 4 */
 5
 6#include <linux/init.h>
 7#include <linux/module.h>
 8#include <linux/kernel.h>
 9#include <linux/of.h>
10#include <linux/nvmem-consumer.h>
11#include <linux/platform_device.h>
12#include <linux/reboot-mode.h>
13#include <linux/slab.h>
14
15struct nvmem_reboot_mode {
16	struct reboot_mode_driver reboot;
17	struct nvmem_cell *cell;
18};
19
20static int nvmem_reboot_mode_write(struct reboot_mode_driver *reboot,
21				    unsigned int magic)
22{
23	struct nvmem_reboot_mode *nvmem_rbm;
24	size_t buf_len;
25	void *buf;
26	int ret;
27
28	nvmem_rbm = container_of(reboot, struct nvmem_reboot_mode, reboot);
29
30	buf = nvmem_cell_read(nvmem_rbm->cell, &buf_len);
31	if (IS_ERR(buf))
32		return PTR_ERR(buf);
33	kfree(buf);
34
35	if (buf_len > sizeof(magic))
36		return -EINVAL;
37
38	ret = nvmem_cell_write(nvmem_rbm->cell, &magic, buf_len);
39	if (ret < 0)
40		dev_err(reboot->dev, "update reboot mode bits failed\n");
41
42	return ret;
43}
44
45static int nvmem_reboot_mode_probe(struct platform_device *pdev)
46{
47	int ret;
48	struct nvmem_reboot_mode *nvmem_rbm;
49
50	nvmem_rbm = devm_kzalloc(&pdev->dev, sizeof(*nvmem_rbm), GFP_KERNEL);
51	if (!nvmem_rbm)
52		return -ENOMEM;
53
54	nvmem_rbm->reboot.dev = &pdev->dev;
55	nvmem_rbm->reboot.write = nvmem_reboot_mode_write;
56
57	nvmem_rbm->cell = devm_nvmem_cell_get(&pdev->dev, "reboot-mode");
58	if (IS_ERR(nvmem_rbm->cell)) {
59		return dev_err_probe(&pdev->dev, PTR_ERR(nvmem_rbm->cell),
60				     "failed to get the nvmem cell reboot-mode\n");
61	}
62
63	ret = devm_reboot_mode_register(&pdev->dev, &nvmem_rbm->reboot);
64	if (ret)
65		dev_err(&pdev->dev, "can't register reboot mode\n");
66
67	return ret;
68}
69
70static const struct of_device_id nvmem_reboot_mode_of_match[] = {
71	{ .compatible = "nvmem-reboot-mode" },
72	{}
73};
74MODULE_DEVICE_TABLE(of, nvmem_reboot_mode_of_match);
75
76static struct platform_driver nvmem_reboot_mode_driver = {
77	.probe = nvmem_reboot_mode_probe,
78	.driver = {
79		.name = "nvmem-reboot-mode",
80		.of_match_table = nvmem_reboot_mode_of_match,
81	},
82};
83module_platform_driver(nvmem_reboot_mode_driver);
84
85MODULE_AUTHOR("Nandor Han <nandor.han@vaisala.com>");
86MODULE_DESCRIPTION("NVMEM reboot mode driver");
87MODULE_LICENSE("GPL");