1 /* 2 * Generic Syscon Reboot Driver 3 * 4 * Copyright (c) 2013, Applied Micro Circuits Corporation 5 * Author: Feng Kan <fkan@apm.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 #include <linux/delay.h> 18 #include <linux/io.h> 19 #include <linux/notifier.h> 20 #include <linux/mfd/syscon.h> 21 #include <linux/of_address.h> 22 #include <linux/of_device.h> 23 #include <linux/platform_device.h> 24 #include <linux/reboot.h> 25 #include <linux/regmap.h> 26 27 struct syscon_reboot_context { 28 struct regmap *map; 29 u32 offset; 30 u32 mask; 31 struct notifier_block restart_handler; 32 }; 33 34 static int syscon_restart_handle(struct notifier_block *this, 35 unsigned long mode, void *cmd) 36 { 37 struct syscon_reboot_context *ctx = 38 container_of(this, struct syscon_reboot_context, 39 restart_handler); 40 41 /* Issue the reboot */ 42 regmap_write(ctx->map, ctx->offset, ctx->mask); 43 44 mdelay(1000); 45 46 pr_emerg("Unable to restart system\n"); 47 return NOTIFY_DONE; 48 } 49 50 static int syscon_reboot_probe(struct platform_device *pdev) 51 { 52 struct syscon_reboot_context *ctx; 53 struct device *dev = &pdev->dev; 54 int err; 55 56 ctx = devm_kzalloc(&pdev->dev, sizeof(*ctx), GFP_KERNEL); 57 if (!ctx) 58 return -ENOMEM; 59 60 ctx->map = syscon_regmap_lookup_by_phandle(dev->of_node, "regmap"); 61 if (IS_ERR(ctx->map)) 62 return PTR_ERR(ctx->map); 63 64 if (of_property_read_u32(pdev->dev.of_node, "offset", &ctx->offset)) 65 return -EINVAL; 66 67 if (of_property_read_u32(pdev->dev.of_node, "mask", &ctx->mask)) 68 return -EINVAL; 69 70 ctx->restart_handler.notifier_call = syscon_restart_handle; 71 ctx->restart_handler.priority = 192; 72 err = register_restart_handler(&ctx->restart_handler); 73 if (err) 74 dev_err(dev, "can't register restart notifier (err=%d)\n", err); 75 76 return err; 77 } 78 79 static const struct of_device_id syscon_reboot_of_match[] = { 80 { .compatible = "syscon-reboot" }, 81 {} 82 }; 83 84 static struct platform_driver syscon_reboot_driver = { 85 .probe = syscon_reboot_probe, 86 .driver = { 87 .name = "syscon-reboot", 88 .of_match_table = syscon_reboot_of_match, 89 }, 90 }; 91 builtin_platform_driver(syscon_reboot_driver); 92