1 /*
2  * Generic Syscon Poweroff Driver
3  *
4  * Copyright (c) 2015, National Instruments Corp.
5  * Author: Moritz Fischer <moritz.fischer@ettus.com>
6  *
7  * This program is free software; you can redistribute it and/or
8  * modify it under the terms of the GNU General Public License as
9  * published by the Free Software Foundation; either version 2 of
10  * the License, or (at your option) any later version.
11  *
12  * This program is distributed in the hope that it will be useful,
13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
15  * GNU General Public License for more details.
16  */
17 
18 #include <linux/kallsyms.h>
19 #include <linux/delay.h>
20 #include <linux/io.h>
21 #include <linux/notifier.h>
22 #include <linux/mfd/syscon.h>
23 #include <linux/of_address.h>
24 #include <linux/of_device.h>
25 #include <linux/platform_device.h>
26 #include <linux/pm.h>
27 #include <linux/regmap.h>
28 
29 static struct regmap *map;
30 static u32 offset;
31 static u32 mask;
32 
33 void syscon_poweroff(void)
34 {
35 	/* Issue the poweroff */
36 	regmap_write(map, offset, mask);
37 
38 	mdelay(1000);
39 
40 	pr_emerg("Unable to poweroff system\n");
41 }
42 
43 static int syscon_poweroff_probe(struct platform_device *pdev)
44 {
45 	char symname[KSYM_NAME_LEN];
46 
47 	map = syscon_regmap_lookup_by_phandle(pdev->dev.of_node, "regmap");
48 	if (IS_ERR(map)) {
49 		dev_err(&pdev->dev, "unable to get syscon");
50 		return PTR_ERR(map);
51 	}
52 
53 	if (of_property_read_u32(pdev->dev.of_node, "offset", &offset)) {
54 		dev_err(&pdev->dev, "unable to read 'offset'");
55 		return -EINVAL;
56 	}
57 
58 	if (of_property_read_u32(pdev->dev.of_node, "mask", &mask)) {
59 		dev_err(&pdev->dev, "unable to read 'mask'");
60 		return -EINVAL;
61 	}
62 
63 	if (pm_power_off) {
64 		lookup_symbol_name((ulong)pm_power_off, symname);
65 		dev_err(&pdev->dev,
66 		"pm_power_off already claimed %p %s",
67 		pm_power_off, symname);
68 		return -EBUSY;
69 	}
70 
71 	pm_power_off = syscon_poweroff;
72 
73 	return 0;
74 }
75 
76 static int syscon_poweroff_remove(struct platform_device *pdev)
77 {
78 	if (pm_power_off == syscon_poweroff)
79 		pm_power_off = NULL;
80 
81 	return 0;
82 }
83 
84 static const struct of_device_id syscon_poweroff_of_match[] = {
85 	{ .compatible = "syscon-poweroff" },
86 	{}
87 };
88 
89 static struct platform_driver syscon_poweroff_driver = {
90 	.probe = syscon_poweroff_probe,
91 	.remove = syscon_poweroff_remove,
92 	.driver = {
93 		.name = "syscon-poweroff",
94 		.of_match_table = syscon_poweroff_of_match,
95 	},
96 };
97 
98 static int __init syscon_poweroff_register(void)
99 {
100 	return platform_driver_register(&syscon_poweroff_driver);
101 }
102 device_initcall(syscon_poweroff_register);
103