1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 *
4 * Copyright (C) 2012 ARM Limited
5 */
6
7#include <linux/delay.h>
8#include <linux/notifier.h>
9#include <linux/of.h>
10#include <linux/platform_device.h>
11#include <linux/property.h>
12#include <linux/reboot.h>
13#include <linux/stat.h>
14#include <linux/vexpress.h>
15
16static void vexpress_reset_do(struct device *dev, const char *what)
17{
18	int err = -ENOENT;
19	struct regmap *reg = dev_get_drvdata(dev);
20
21	if (reg) {
22		err = regmap_write(reg, 0, 0);
23		if (!err)
24			mdelay(1000);
25	}
26
27	dev_emerg(dev, "Unable to %s (%d)\n", what, err);
28}
29
30static struct device *vexpress_power_off_device;
31static atomic_t vexpress_restart_nb_refcnt = ATOMIC_INIT(0);
32
33static void vexpress_power_off(void)
34{
35	vexpress_reset_do(vexpress_power_off_device, "power off");
36}
37
38static struct device *vexpress_restart_device;
39
40static int vexpress_restart(struct notifier_block *this, unsigned long mode,
41			     void *cmd)
42{
43	vexpress_reset_do(vexpress_restart_device, "restart");
44
45	return NOTIFY_DONE;
46}
47
48static struct notifier_block vexpress_restart_nb = {
49	.notifier_call = vexpress_restart,
50	.priority = 128,
51};
52
53static ssize_t vexpress_reset_active_show(struct device *dev,
54		struct device_attribute *attr, char *buf)
55{
56	return sprintf(buf, "%d\n", vexpress_restart_device == dev);
57}
58
59static ssize_t vexpress_reset_active_store(struct device *dev,
60		struct device_attribute *attr, const char *buf, size_t count)
61{
62	long value;
63	int err = kstrtol(buf, 0, &value);
64
65	if (!err && value)
66		vexpress_restart_device = dev;
67
68	return err ? err : count;
69}
70
71static DEVICE_ATTR(active, S_IRUGO | S_IWUSR, vexpress_reset_active_show,
72		   vexpress_reset_active_store);
73
74
75enum vexpress_reset_func { FUNC_RESET, FUNC_SHUTDOWN, FUNC_REBOOT };
76
77static const struct of_device_id vexpress_reset_of_match[] = {
78	{
79		.compatible = "arm,vexpress-reset",
80		.data = (void *)FUNC_RESET,
81	}, {
82		.compatible = "arm,vexpress-shutdown",
83		.data = (void *)FUNC_SHUTDOWN
84	}, {
85		.compatible = "arm,vexpress-reboot",
86		.data = (void *)FUNC_REBOOT
87	},
88	{}
89};
90
91static int _vexpress_register_restart_handler(struct device *dev)
92{
93	int err;
94
95	vexpress_restart_device = dev;
96	if (atomic_inc_return(&vexpress_restart_nb_refcnt) == 1) {
97		err = register_restart_handler(&vexpress_restart_nb);
98		if (err) {
99			dev_err(dev, "cannot register restart handler (err=%d)\n", err);
100			atomic_dec(&vexpress_restart_nb_refcnt);
101			return err;
102		}
103	}
104	device_create_file(dev, &dev_attr_active);
105
106	return 0;
107}
108
109static int vexpress_reset_probe(struct platform_device *pdev)
110{
111	enum vexpress_reset_func func;
112	struct regmap *regmap;
113	int ret = 0;
114
115	regmap = devm_regmap_init_vexpress_config(&pdev->dev);
116	if (IS_ERR(regmap))
117		return PTR_ERR(regmap);
118	dev_set_drvdata(&pdev->dev, regmap);
119
120	func = (uintptr_t)device_get_match_data(&pdev->dev);
121	switch (func) {
122	case FUNC_SHUTDOWN:
123		vexpress_power_off_device = &pdev->dev;
124		pm_power_off = vexpress_power_off;
125		break;
126	case FUNC_RESET:
127		if (!vexpress_restart_device)
128			ret = _vexpress_register_restart_handler(&pdev->dev);
129		break;
130	case FUNC_REBOOT:
131		ret = _vexpress_register_restart_handler(&pdev->dev);
132		break;
133	}
134
135	return ret;
136}
137
138static struct platform_driver vexpress_reset_driver = {
139	.probe = vexpress_reset_probe,
140	.driver = {
141		.name = "vexpress-reset",
142		.of_match_table = vexpress_reset_of_match,
143		.suppress_bind_attrs = true,
144	},
145};
146builtin_platform_driver(vexpress_reset_driver);
147