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 value;
32 static u32 mask;
33 
34 static void syscon_poweroff(void)
35 {
36 	/* Issue the poweroff */
37 	regmap_update_bits(map, offset, mask, value);
38 
39 	mdelay(1000);
40 
41 	pr_emerg("Unable to poweroff system\n");
42 }
43 
44 static int syscon_poweroff_probe(struct platform_device *pdev)
45 {
46 	char symname[KSYM_NAME_LEN];
47 	int mask_err, value_err;
48 
49 	map = syscon_regmap_lookup_by_phandle(pdev->dev.of_node, "regmap");
50 	if (IS_ERR(map)) {
51 		dev_err(&pdev->dev, "unable to get syscon");
52 		return PTR_ERR(map);
53 	}
54 
55 	if (of_property_read_u32(pdev->dev.of_node, "offset", &offset)) {
56 		dev_err(&pdev->dev, "unable to read 'offset'");
57 		return -EINVAL;
58 	}
59 
60 	value_err = of_property_read_u32(pdev->dev.of_node, "value", &value);
61 	mask_err = of_property_read_u32(pdev->dev.of_node, "mask", &mask);
62 	if (value_err && mask_err) {
63 		dev_err(&pdev->dev, "unable to read 'value' and 'mask'");
64 		return -EINVAL;
65 	}
66 
67 	if (value_err) {
68 		/* support old binding */
69 		value = mask;
70 		mask = 0xFFFFFFFF;
71 	} else if (mask_err) {
72 		/* support value without mask*/
73 		mask = 0xFFFFFFFF;
74 	}
75 
76 	if (pm_power_off) {
77 		lookup_symbol_name((ulong)pm_power_off, symname);
78 		dev_err(&pdev->dev,
79 		"pm_power_off already claimed %p %s",
80 		pm_power_off, symname);
81 		return -EBUSY;
82 	}
83 
84 	pm_power_off = syscon_poweroff;
85 
86 	return 0;
87 }
88 
89 static int syscon_poweroff_remove(struct platform_device *pdev)
90 {
91 	if (pm_power_off == syscon_poweroff)
92 		pm_power_off = NULL;
93 
94 	return 0;
95 }
96 
97 static const struct of_device_id syscon_poweroff_of_match[] = {
98 	{ .compatible = "syscon-poweroff" },
99 	{}
100 };
101 
102 static struct platform_driver syscon_poweroff_driver = {
103 	.probe = syscon_poweroff_probe,
104 	.remove = syscon_poweroff_remove,
105 	.driver = {
106 		.name = "syscon-poweroff",
107 		.of_match_table = syscon_poweroff_of_match,
108 	},
109 };
110 
111 static int __init syscon_poweroff_register(void)
112 {
113 	return platform_driver_register(&syscon_poweroff_driver);
114 }
115 device_initcall(syscon_poweroff_register);
116