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 value; 31 u32 mask; 32 struct notifier_block restart_handler; 33 }; 34 35 static int syscon_restart_handle(struct notifier_block *this, 36 unsigned long mode, void *cmd) 37 { 38 struct syscon_reboot_context *ctx = 39 container_of(this, struct syscon_reboot_context, 40 restart_handler); 41 42 /* Issue the reboot */ 43 regmap_update_bits(ctx->map, ctx->offset, ctx->mask, ctx->value); 44 45 mdelay(1000); 46 47 pr_emerg("Unable to restart system\n"); 48 return NOTIFY_DONE; 49 } 50 51 static int syscon_reboot_probe(struct platform_device *pdev) 52 { 53 struct syscon_reboot_context *ctx; 54 struct device *dev = &pdev->dev; 55 int mask_err, value_err; 56 int err; 57 58 ctx = devm_kzalloc(&pdev->dev, sizeof(*ctx), GFP_KERNEL); 59 if (!ctx) 60 return -ENOMEM; 61 62 ctx->map = syscon_regmap_lookup_by_phandle(dev->of_node, "regmap"); 63 if (IS_ERR(ctx->map)) 64 return PTR_ERR(ctx->map); 65 66 if (of_property_read_u32(pdev->dev.of_node, "offset", &ctx->offset)) 67 return -EINVAL; 68 69 value_err = of_property_read_u32(pdev->dev.of_node, "value", &ctx->value); 70 mask_err = of_property_read_u32(pdev->dev.of_node, "mask", &ctx->mask); 71 if (value_err && mask_err) { 72 dev_err(dev, "unable to read 'value' and 'mask'"); 73 return -EINVAL; 74 } 75 76 if (value_err) { 77 /* support old binding */ 78 ctx->value = ctx->mask; 79 ctx->mask = 0xFFFFFFFF; 80 } else if (mask_err) { 81 /* support value without mask*/ 82 ctx->mask = 0xFFFFFFFF; 83 } 84 85 ctx->restart_handler.notifier_call = syscon_restart_handle; 86 ctx->restart_handler.priority = 192; 87 err = register_restart_handler(&ctx->restart_handler); 88 if (err) 89 dev_err(dev, "can't register restart notifier (err=%d)\n", err); 90 91 return err; 92 } 93 94 static const struct of_device_id syscon_reboot_of_match[] = { 95 { .compatible = "syscon-reboot" }, 96 {} 97 }; 98 99 static struct platform_driver syscon_reboot_driver = { 100 .probe = syscon_reboot_probe, 101 .driver = { 102 .name = "syscon-reboot", 103 .of_match_table = syscon_reboot_of_match, 104 }, 105 }; 106 builtin_platform_driver(syscon_reboot_driver); 107