syscon-reboot.c

  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
 17struct reboot_mode_bits {
 18	u32 offset;
 19	u32 mask;
 20	u32 value;
 21	bool valid;
 22};
 23
 24struct reboot_data {
 25	struct reboot_mode_bits mode_bits[REBOOT_SOFT + 1];
 26	struct reboot_mode_bits catchall;
 27};
 28
 29struct syscon_reboot_context {
 30	struct regmap *map;
 31
 32	const struct reboot_data *rd; /* from of match data, if any */
 33	struct reboot_mode_bits catchall; /* from DT */
 34
 35	struct notifier_block restart_handler;
 36};
 37
 38static int syscon_restart_handle(struct notifier_block *this,
 39					unsigned long mode, void *cmd)
 40{
 41	struct syscon_reboot_context *ctx =
 42			container_of(this, struct syscon_reboot_context,
 43					restart_handler);
 44	const struct reboot_mode_bits *mode_bits;
 45
 46	if (ctx->rd) {
 47		if (mode < ARRAY_SIZE(ctx->rd->mode_bits) &&
 48		    ctx->rd->mode_bits[mode].valid)
 49			mode_bits = &ctx->rd->mode_bits[mode];
 50		else
 51			mode_bits = &ctx->rd->catchall;
 52	} else {
 53		mode_bits = &ctx->catchall;
 54	}
 55
 56	/* Issue the reboot */
 57	regmap_update_bits(ctx->map, mode_bits->offset, mode_bits->mask,
 58			   mode_bits->value);
 59
 60	mdelay(1000);
 61
 62	pr_emerg("Unable to restart system\n");
 63	return NOTIFY_DONE;
 64}
 65
 66static int syscon_reboot_probe(struct platform_device *pdev)
 67{
 68	struct syscon_reboot_context *ctx;
 69	struct device *dev = &pdev->dev;
 70	int priority;
 71	int err;
 72
 73	ctx = devm_kzalloc(&pdev->dev, sizeof(*ctx), GFP_KERNEL);
 74	if (!ctx)
 75		return -ENOMEM;
 76
 77	ctx->map = syscon_regmap_lookup_by_phandle(dev->of_node, "regmap");
 78	if (IS_ERR(ctx->map)) {
 79		ctx->map = syscon_node_to_regmap(dev->parent->of_node);
 80		if (IS_ERR(ctx->map))
 81			return PTR_ERR(ctx->map);
 82	}
 83
 84	if (of_property_read_s32(pdev->dev.of_node, "priority", &priority))
 85		priority = 192;
 86
 87	ctx->rd = of_device_get_match_data(dev);
 88	if (!ctx->rd) {
 89		int mask_err, value_err;
 90
 91		if (of_property_read_u32(pdev->dev.of_node, "offset",
 92					 &ctx->catchall.offset) &&
 93		    of_property_read_u32(pdev->dev.of_node, "reg",
 94					 &ctx->catchall.offset))
 95			return -EINVAL;
 96
 97		value_err = of_property_read_u32(pdev->dev.of_node, "value",
 98						 &ctx->catchall.value);
 99		mask_err = of_property_read_u32(pdev->dev.of_node, "mask",
100						&ctx->catchall.mask);
101		if (value_err && mask_err) {
102			dev_err(dev, "unable to read 'value' and 'mask'");
103			return -EINVAL;
104		}
105
106		if (value_err) {
107			/* support old binding */
108			ctx->catchall.value = ctx->catchall.mask;
109			ctx->catchall.mask = 0xFFFFFFFF;
110		} else if (mask_err) {
111			/* support value without mask */
112			ctx->catchall.mask = 0xFFFFFFFF;
113		}
114	}
115
116	ctx->restart_handler.notifier_call = syscon_restart_handle;
117	ctx->restart_handler.priority = priority;
118	err = register_restart_handler(&ctx->restart_handler);
119	if (err)
120		dev_err(dev, "can't register restart notifier (err=%d)\n", err);
121
122	return err;
123}
124
125static const struct reboot_data gs101_reboot_data = {
126	.mode_bits = {
127		[REBOOT_WARM] = {
128			.offset = 0x3a00, /* SYSTEM_CONFIGURATION */
129			.mask = 0x00000002, /* SWRESET_SYSTEM */
130			.value = 0x00000002,
131			.valid = true,
132		},
133		[REBOOT_SOFT] = {
134			.offset = 0x3a00, /* SYSTEM_CONFIGURATION */
135			.mask = 0x00000002, /* SWRESET_SYSTEM */
136			.value = 0x00000002,
137			.valid = true,
138		},
139	},
140	.catchall = {
141		.offset = 0x3e9c, /* PAD_CTRL_PWR_HOLD */
142		.mask = 0x00000100,
143		.value = 0x00000000,
144	},
145};
146
147static const struct of_device_id syscon_reboot_of_match[] = {
148	{ .compatible = "google,gs101-reboot", .data = &gs101_reboot_data  },
149	{ .compatible = "syscon-reboot" },
150	{}
151};
152
153static struct platform_driver syscon_reboot_driver = {
154	.probe = syscon_reboot_probe,
155	.driver = {
156		.name = "syscon-reboot",
157		.of_match_table = syscon_reboot_of_match,
158	},
159};
160builtin_platform_driver(syscon_reboot_driver);