power/reset/syscon-reboot.c

0001 // SPDX-License-Identifier: GPL-2.0-or-later
0002 /*
0003  * Generic Syscon Reboot Driver
0004  *
0005  * Copyright (c) 2013, Applied Micro Circuits Corporation
0006  * Author: Feng Kan <fkan@apm.com>
0007  */
0008 #include <linux/delay.h>
0009 #include <linux/io.h>
0010 #include <linux/notifier.h>
0011 #include <linux/mfd/syscon.h>
0012 #include <linux/of_address.h>
0013 #include <linux/of_device.h>
0014 #include <linux/platform_device.h>
0015 #include <linux/reboot.h>
0016 #include <linux/regmap.h>
0017
0018 struct syscon_reboot_context {
0019     struct regmap *map;
0020     u32 offset;
0021     u32 value;
0022     u32 mask;
0023     struct notifier_block restart_handler;
0024 };
0025
0026 static int syscon_restart_handle(struct notifier_block *this,
0027                     unsigned long mode, void *cmd)
0028 {
0029     struct syscon_reboot_context *ctx =
0030             container_of(this, struct syscon_reboot_context,
0031                     restart_handler);
0032
0033     /* Issue the reboot */
0034     regmap_update_bits(ctx->map, ctx->offset, ctx->mask, ctx->value);
0035
0036     mdelay(1000);
0037
0038     pr_emerg("Unable to restart system\n");
0039     return NOTIFY_DONE;
0040 }
0041
0042 static int syscon_reboot_probe(struct platform_device *pdev)
0043 {
0044     struct syscon_reboot_context *ctx;
0045     struct device *dev = &pdev->dev;
0046     int mask_err, value_err;
0047     int err;
0048
0049     ctx = devm_kzalloc(&pdev->dev, sizeof(*ctx), GFP_KERNEL);
0050     if (!ctx)
0051         return -ENOMEM;
0052
0053     ctx->map = syscon_regmap_lookup_by_phandle(dev->of_node, "regmap");
0054     if (IS_ERR(ctx->map)) {
0055         ctx->map = syscon_node_to_regmap(dev->parent->of_node);
0056         if (IS_ERR(ctx->map))
0057             return PTR_ERR(ctx->map);
0058     }
0059
0060     if (of_property_read_u32(pdev->dev.of_node, "offset", &ctx->offset))
0061         return -EINVAL;
0062
0063     value_err = of_property_read_u32(pdev->dev.of_node, "value", &ctx->value);
0064     mask_err = of_property_read_u32(pdev->dev.of_node, "mask", &ctx->mask);
0065     if (value_err && mask_err) {
0066         dev_err(dev, "unable to read 'value' and 'mask'");
0067         return -EINVAL;
0068     }
0069
0070     if (value_err) {
0071         /* support old binding */
0072         ctx->value = ctx->mask;
0073         ctx->mask = 0xFFFFFFFF;
0074     } else if (mask_err) {
0075         /* support value without mask*/
0076         ctx->mask = 0xFFFFFFFF;
0077     }
0078
0079     ctx->restart_handler.notifier_call = syscon_restart_handle;
0080     ctx->restart_handler.priority = 192;
0081     err = register_restart_handler(&ctx->restart_handler);
0082     if (err)
0083         dev_err(dev, "can't register restart notifier (err=%d)\n", err);
0084
0085     return err;
0086 }
0087
0088 static const struct of_device_id syscon_reboot_of_match[] = {
0089     { .compatible = "syscon-reboot" },
0090     {}
0091 };
0092
0093 static struct platform_driver syscon_reboot_driver = {
0094     .probe = syscon_reboot_probe,
0095     .driver = {
0096         .name = "syscon-reboot",
0097         .of_match_table = syscon_reboot_of_match,
0098     },
0099 };
0100 builtin_platform_driver(syscon_reboot_driver);