1 // SPDX-License-Identifier: GPL-2.0-or-later 2 /* 3 * Generic Syscon Reboot Driver 4 * 5 * Copyright (c) 2013, Applied Micro Circuits Corporation 6 * Author: Feng Kan <fkan@apm.com> 7 */ 8 #include <linux/delay.h> 9 #include <linux/io.h> 10 #include <linux/notifier.h> 11 #include <linux/mfd/syscon.h> 12 #include <linux/of_address.h> 13 #include <linux/of_device.h> 14 #include <linux/platform_device.h> 15 #include <linux/reboot.h> 16 #include <linux/regmap.h> 17 18 struct syscon_reboot_context { 19 struct regmap *map; 20 u32 offset; 21 u32 value; 22 u32 mask; 23 struct notifier_block restart_handler; 24 }; 25 26 static int syscon_restart_handle(struct notifier_block *this, 27 unsigned long mode, void *cmd) 28 { 29 struct syscon_reboot_context *ctx = 30 container_of(this, struct syscon_reboot_context, 31 restart_handler); 32 33 /* Issue the reboot */ 34 regmap_update_bits(ctx->map, ctx->offset, ctx->mask, ctx->value); 35 36 mdelay(1000); 37 38 pr_emerg("Unable to restart system\n"); 39 return NOTIFY_DONE; 40 } 41 42 static int syscon_reboot_probe(struct platform_device *pdev) 43 { 44 struct syscon_reboot_context *ctx; 45 struct device *dev = &pdev->dev; 46 int mask_err, value_err; 47 int err; 48 49 ctx = devm_kzalloc(&pdev->dev, sizeof(*ctx), GFP_KERNEL); 50 if (!ctx) 51 return -ENOMEM; 52 53 ctx->map = syscon_regmap_lookup_by_phandle(dev->of_node, "regmap"); 54 if (IS_ERR(ctx->map)) 55 return PTR_ERR(ctx->map); 56 57 if (of_property_read_u32(pdev->dev.of_node, "offset", &ctx->offset)) 58 return -EINVAL; 59 60 value_err = of_property_read_u32(pdev->dev.of_node, "value", &ctx->value); 61 mask_err = of_property_read_u32(pdev->dev.of_node, "mask", &ctx->mask); 62 if (value_err && mask_err) { 63 dev_err(dev, "unable to read 'value' and 'mask'"); 64 return -EINVAL; 65 } 66 67 if (value_err) { 68 /* support old binding */ 69 ctx->value = ctx->mask; 70 ctx->mask = 0xFFFFFFFF; 71 } else if (mask_err) { 72 /* support value without mask*/ 73 ctx->mask = 0xFFFFFFFF; 74 } 75 76 ctx->restart_handler.notifier_call = syscon_restart_handle; 77 ctx->restart_handler.priority = 192; 78 err = register_restart_handler(&ctx->restart_handler); 79 if (err) 80 dev_err(dev, "can't register restart notifier (err=%d)\n", err); 81 82 return err; 83 } 84 85 static const struct of_device_id syscon_reboot_of_match[] = { 86 { .compatible = "syscon-reboot" }, 87 {} 88 }; 89 90 static struct platform_driver syscon_reboot_driver = { 91 .probe = syscon_reboot_probe, 92 .driver = { 93 .name = "syscon-reboot", 94 .of_match_table = syscon_reboot_of_match, 95 }, 96 }; 97 builtin_platform_driver(syscon_reboot_driver); 98