1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3  * AppliedMicro X-Gene SoC Reboot Driver
4  *
5  * Copyright (c) 2013, Applied Micro Circuits Corporation
6  * Author: Feng Kan <fkan@apm.com>
7  * Author: Loc Ho <lho@apm.com>
8  *
9  * This driver provides system reboot functionality for APM X-Gene SoC.
10  * For system shutdown, this is board specify. If a board designer
11  * implements GPIO shutdown, use the gpio-poweroff.c driver.
12  */
13 #include <linux/delay.h>
14 #include <linux/io.h>
15 #include <linux/notifier.h>
16 #include <linux/of_device.h>
17 #include <linux/of_address.h>
18 #include <linux/platform_device.h>
19 #include <linux/reboot.h>
20 #include <linux/stat.h>
21 #include <linux/slab.h>
22 
23 struct xgene_reboot_context {
24 	struct device *dev;
25 	void *csr;
26 	u32 mask;
27 	struct notifier_block restart_handler;
28 };
29 
30 static int xgene_restart_handler(struct notifier_block *this,
31 				 unsigned long mode, void *cmd)
32 {
33 	struct xgene_reboot_context *ctx =
34 		container_of(this, struct xgene_reboot_context,
35 			     restart_handler);
36 
37 	/* Issue the reboot */
38 	writel(ctx->mask, ctx->csr);
39 
40 	mdelay(1000);
41 
42 	dev_emerg(ctx->dev, "Unable to restart system\n");
43 
44 	return NOTIFY_DONE;
45 }
46 
47 static int xgene_reboot_probe(struct platform_device *pdev)
48 {
49 	struct xgene_reboot_context *ctx;
50 	struct device *dev = &pdev->dev;
51 	int err;
52 
53 	ctx = devm_kzalloc(dev, sizeof(*ctx), GFP_KERNEL);
54 	if (!ctx)
55 		return -ENOMEM;
56 
57 	ctx->csr = of_iomap(dev->of_node, 0);
58 	if (!ctx->csr) {
59 		dev_err(dev, "can not map resource\n");
60 		return -ENODEV;
61 	}
62 
63 	if (of_property_read_u32(dev->of_node, "mask", &ctx->mask))
64 		ctx->mask = 0xFFFFFFFF;
65 
66 	ctx->dev = dev;
67 	ctx->restart_handler.notifier_call = xgene_restart_handler;
68 	ctx->restart_handler.priority = 128;
69 	err = register_restart_handler(&ctx->restart_handler);
70 	if (err) {
71 		iounmap(ctx->csr);
72 		dev_err(dev, "cannot register restart handler (err=%d)\n", err);
73 	}
74 
75 	return err;
76 }
77 
78 static const struct of_device_id xgene_reboot_of_match[] = {
79 	{ .compatible = "apm,xgene-reboot" },
80 	{}
81 };
82 
83 static struct platform_driver xgene_reboot_driver = {
84 	.probe = xgene_reboot_probe,
85 	.driver = {
86 		.name = "xgene-reboot",
87 		.of_match_table = xgene_reboot_of_match,
88 	},
89 };
90 
91 static int __init xgene_reboot_init(void)
92 {
93 	return platform_driver_register(&xgene_reboot_driver);
94 }
95 device_initcall(xgene_reboot_init);
96