1 /*
2  * AppliedMicro X-Gene SoC Reboot Driver
3  *
4  * Copyright (c) 2013, Applied Micro Circuits Corporation
5  * Author: Feng Kan <fkan@apm.com>
6  * Author: Loc Ho <lho@apm.com>
7  *
8  * This program is free software; you can redistribute it and/or
9  * modify it under the terms of the GNU General Public License as
10  * published by the Free Software Foundation; either version 2 of
11  * the License, or (at your option) any later version.
12  *
13  * This program is distributed in the hope that it will be useful,
14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
16  * GNU General Public License for more details.
17  *
18  * You should have received a copy of the GNU General Public License
19  * along with this program; if not, write to the Free Software
20  * Foundation, Inc., 59 Temple Place, Suite 330, Boston,
21  * MA 02111-1307 USA
22  *
23  * This driver provides system reboot functionality for APM X-Gene SoC.
24  * For system shutdown, this is board specify. If a board designer
25  * implements GPIO shutdown, use the gpio-poweroff.c driver.
26  */
27 #include <linux/io.h>
28 #include <linux/of_device.h>
29 #include <linux/of_address.h>
30 #include <linux/platform_device.h>
31 #include <linux/stat.h>
32 #include <linux/slab.h>
33 #include <asm/system_misc.h>
34 
35 struct xgene_reboot_context {
36 	struct platform_device *pdev;
37 	void *csr;
38 	u32 mask;
39 };
40 
41 static struct xgene_reboot_context *xgene_restart_ctx;
42 
43 static void xgene_restart(enum reboot_mode mode, const char *cmd)
44 {
45 	struct xgene_reboot_context *ctx = xgene_restart_ctx;
46 	unsigned long timeout;
47 
48 	/* Issue the reboot */
49 	if (ctx)
50 		writel(ctx->mask, ctx->csr);
51 
52 	timeout = jiffies + HZ;
53 	while (time_before(jiffies, timeout))
54 		cpu_relax();
55 
56 	dev_emerg(&ctx->pdev->dev, "Unable to restart system\n");
57 }
58 
59 static int xgene_reboot_probe(struct platform_device *pdev)
60 {
61 	struct xgene_reboot_context *ctx;
62 
63 	ctx = devm_kzalloc(&pdev->dev, sizeof(*ctx), GFP_KERNEL);
64 	if (!ctx) {
65 		dev_err(&pdev->dev, "out of memory for context\n");
66 		return -ENODEV;
67 	}
68 
69 	ctx->csr = of_iomap(pdev->dev.of_node, 0);
70 	if (!ctx->csr) {
71 		devm_kfree(&pdev->dev, ctx);
72 		dev_err(&pdev->dev, "can not map resource\n");
73 		return -ENODEV;
74 	}
75 
76 	if (of_property_read_u32(pdev->dev.of_node, "mask", &ctx->mask))
77 		ctx->mask = 0xFFFFFFFF;
78 
79 	ctx->pdev = pdev;
80 	arm_pm_restart = xgene_restart;
81 	xgene_restart_ctx = ctx;
82 
83 	return 0;
84 }
85 
86 static struct of_device_id xgene_reboot_of_match[] = {
87 	{ .compatible = "apm,xgene-reboot" },
88 	{}
89 };
90 
91 static struct platform_driver xgene_reboot_driver = {
92 	.probe = xgene_reboot_probe,
93 	.driver = {
94 		.name = "xgene-reboot",
95 		.of_match_table = xgene_reboot_of_match,
96 	},
97 };
98 
99 static int __init xgene_reboot_init(void)
100 {
101 	return platform_driver_register(&xgene_reboot_driver);
102 }
103 device_initcall(xgene_reboot_init);
104