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.h> 13 #include <linux/platform_device.h> 14 #include <linux/reboot.h> 15 #include <linux/regmap.h> 16 17 struct syscon_reboot_context { 18 struct regmap *map; 19 u32 offset; 20 u32 value; 21 u32 mask; 22 struct notifier_block restart_handler; 23 }; 24 25 static int syscon_restart_handle(struct notifier_block *this, 26 unsigned long mode, void *cmd) 27 { 28 struct syscon_reboot_context *ctx = 29 container_of(this, struct syscon_reboot_context, 30 restart_handler); 31 32 /* Issue the reboot */ 33 regmap_update_bits(ctx->map, ctx->offset, ctx->mask, ctx->value); 34 35 mdelay(1000); 36 37 pr_emerg("Unable to restart system\n"); 38 return NOTIFY_DONE; 39 } 40 41 static int syscon_reboot_probe(struct platform_device *pdev) 42 { 43 struct syscon_reboot_context *ctx; 44 struct device *dev = &pdev->dev; 45 int mask_err, value_err; 46 int priority; 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 ctx->map = syscon_node_to_regmap(dev->parent->of_node); 56 if (IS_ERR(ctx->map)) 57 return PTR_ERR(ctx->map); 58 } 59 60 if (of_property_read_s32(pdev->dev.of_node, "priority", &priority)) 61 priority = 192; 62 63 if (of_property_read_u32(pdev->dev.of_node, "offset", &ctx->offset)) 64 if (of_property_read_u32(pdev->dev.of_node, "reg", &ctx->offset)) 65 return -EINVAL; 66 67 value_err = of_property_read_u32(pdev->dev.of_node, "value", &ctx->value); 68 mask_err = of_property_read_u32(pdev->dev.of_node, "mask", &ctx->mask); 69 if (value_err && mask_err) { 70 dev_err(dev, "unable to read 'value' and 'mask'"); 71 return -EINVAL; 72 } 73 74 if (value_err) { 75 /* support old binding */ 76 ctx->value = ctx->mask; 77 ctx->mask = 0xFFFFFFFF; 78 } else if (mask_err) { 79 /* support value without mask*/ 80 ctx->mask = 0xFFFFFFFF; 81 } 82 83 ctx->restart_handler.notifier_call = syscon_restart_handle; 84 ctx->restart_handler.priority = priority; 85 err = register_restart_handler(&ctx->restart_handler); 86 if (err) 87 dev_err(dev, "can't register restart notifier (err=%d)\n", err); 88 89 return err; 90 } 91 92 static const struct of_device_id syscon_reboot_of_match[] = { 93 { .compatible = "syscon-reboot" }, 94 {} 95 }; 96 97 static struct platform_driver syscon_reboot_driver = { 98 .probe = syscon_reboot_probe, 99 .driver = { 100 .name = "syscon-reboot", 101 .of_match_table = syscon_reboot_of_match, 102 }, 103 }; 104 builtin_platform_driver(syscon_reboot_driver); 105