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/of_device.h>
11 #include <linux/platform_device.h>
12 #include <linux/reboot.h>
13 #include <linux/stat.h>
14 #include <linux/vexpress.h>
15 
16 static 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 
30 static struct device *vexpress_power_off_device;
31 static atomic_t vexpress_restart_nb_refcnt = ATOMIC_INIT(0);
32 
33 static void vexpress_power_off(void)
34 {
35 	vexpress_reset_do(vexpress_power_off_device, "power off");
36 }
37 
38 static struct device *vexpress_restart_device;
39 
40 static 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 
48 static struct notifier_block vexpress_restart_nb = {
49 	.notifier_call = vexpress_restart,
50 	.priority = 128,
51 };
52 
53 static 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 
59 static 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 
71 static DEVICE_ATTR(active, S_IRUGO | S_IWUSR, vexpress_reset_active_show,
72 		   vexpress_reset_active_store);
73 
74 
75 enum vexpress_reset_func { FUNC_RESET, FUNC_SHUTDOWN, FUNC_REBOOT };
76 
77 static 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 
91 static 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 
109 static int vexpress_reset_probe(struct platform_device *pdev)
110 {
111 	const struct of_device_id *match =
112 			of_match_device(vexpress_reset_of_match, &pdev->dev);
113 	struct regmap *regmap;
114 	int ret = 0;
115 
116 	if (!match)
117 		return -EINVAL;
118 
119 	regmap = devm_regmap_init_vexpress_config(&pdev->dev);
120 	if (IS_ERR(regmap))
121 		return PTR_ERR(regmap);
122 	dev_set_drvdata(&pdev->dev, regmap);
123 
124 	switch ((enum vexpress_reset_func)match->data) {
125 	case FUNC_SHUTDOWN:
126 		vexpress_power_off_device = &pdev->dev;
127 		pm_power_off = vexpress_power_off;
128 		break;
129 	case FUNC_RESET:
130 		if (!vexpress_restart_device)
131 			ret = _vexpress_register_restart_handler(&pdev->dev);
132 		break;
133 	case FUNC_REBOOT:
134 		ret = _vexpress_register_restart_handler(&pdev->dev);
135 		break;
136 	};
137 
138 	return ret;
139 }
140 
141 static struct platform_driver vexpress_reset_driver = {
142 	.probe = vexpress_reset_probe,
143 	.driver = {
144 		.name = "vexpress-reset",
145 		.of_match_table = vexpress_reset_of_match,
146 	},
147 };
148 
149 static int __init vexpress_reset_init(void)
150 {
151 	return platform_driver_register(&vexpress_reset_driver);
152 }
153 device_initcall(vexpress_reset_init);
154