1// SPDX-License-Identifier: GPL-2.0-or-later
  2/*
  3 * BCM6345 Reset Controller Driver
  4 *
  5 * Copyright (C) 2020 Álvaro Fernández Rojas <noltari@gmail.com>
  6 */
  7
  8#include <linux/delay.h>
  9#include <linux/init.h>
 10#include <linux/io.h>
 11#include <linux/mod_devicetable.h>
 12#include <linux/platform_device.h>
 13#include <linux/reset-controller.h>
 14
 15#define BCM6345_RESET_NUM		32
 16#define BCM6345_RESET_SLEEP_MIN_US	10000
 17#define BCM6345_RESET_SLEEP_MAX_US	20000
 18
 19struct bcm6345_reset {
 20	struct reset_controller_dev rcdev;
 21	void __iomem *base;
 22	spinlock_t lock;
 23};
 24
 25static inline struct bcm6345_reset *
 26to_bcm6345_reset(struct reset_controller_dev *rcdev)
 27{
 28	return container_of(rcdev, struct bcm6345_reset, rcdev);
 29}
 30
 31static int bcm6345_reset_update(struct reset_controller_dev *rcdev,
 32				unsigned long id, bool assert)
 33{
 34	struct bcm6345_reset *bcm6345_reset = to_bcm6345_reset(rcdev);
 35	unsigned long flags;
 36	uint32_t val;
 37
 38	spin_lock_irqsave(&bcm6345_reset->lock, flags);
 39	val = __raw_readl(bcm6345_reset->base);
 40	if (assert)
 41		val &= ~BIT(id);
 42	else
 43		val |= BIT(id);
 44	__raw_writel(val, bcm6345_reset->base);
 45	spin_unlock_irqrestore(&bcm6345_reset->lock, flags);
 46
 47	return 0;
 48}
 49
 50static int bcm6345_reset_assert(struct reset_controller_dev *rcdev,
 51				unsigned long id)
 52{
 53	return bcm6345_reset_update(rcdev, id, true);
 54}
 55
 56static int bcm6345_reset_deassert(struct reset_controller_dev *rcdev,
 57				  unsigned long id)
 58{
 59	return bcm6345_reset_update(rcdev, id, false);
 60}
 61
 62static int bcm6345_reset_reset(struct reset_controller_dev *rcdev,
 63			       unsigned long id)
 64{
 65	bcm6345_reset_update(rcdev, id, true);
 66	usleep_range(BCM6345_RESET_SLEEP_MIN_US,
 67		     BCM6345_RESET_SLEEP_MAX_US);
 68
 69	bcm6345_reset_update(rcdev, id, false);
 70	/*
 71	 * Ensure component is taken out reset state by sleeping also after
 72	 * deasserting the reset. Otherwise, the component may not be ready
 73	 * for operation.
 74	 */
 75	usleep_range(BCM6345_RESET_SLEEP_MIN_US,
 76		     BCM6345_RESET_SLEEP_MAX_US);
 77
 78	return 0;
 79}
 80
 81static int bcm6345_reset_status(struct reset_controller_dev *rcdev,
 82				unsigned long id)
 83{
 84	struct bcm6345_reset *bcm6345_reset = to_bcm6345_reset(rcdev);
 85
 86	return !(__raw_readl(bcm6345_reset->base) & BIT(id));
 87}
 88
 89static const struct reset_control_ops bcm6345_reset_ops = {
 90	.assert = bcm6345_reset_assert,
 91	.deassert = bcm6345_reset_deassert,
 92	.reset = bcm6345_reset_reset,
 93	.status = bcm6345_reset_status,
 94};
 95
 96static int bcm6345_reset_probe(struct platform_device *pdev)
 97{
 98	struct bcm6345_reset *bcm6345_reset;
 99
100	bcm6345_reset = devm_kzalloc(&pdev->dev,
101				     sizeof(*bcm6345_reset), GFP_KERNEL);
102	if (!bcm6345_reset)
103		return -ENOMEM;
104
105	platform_set_drvdata(pdev, bcm6345_reset);
106
107	bcm6345_reset->base = devm_platform_ioremap_resource(pdev, 0);
108	if (IS_ERR(bcm6345_reset->base))
109		return PTR_ERR(bcm6345_reset->base);
110
111	spin_lock_init(&bcm6345_reset->lock);
112	bcm6345_reset->rcdev.ops = &bcm6345_reset_ops;
113	bcm6345_reset->rcdev.owner = THIS_MODULE;
114	bcm6345_reset->rcdev.of_node = pdev->dev.of_node;
115	bcm6345_reset->rcdev.of_reset_n_cells = 1;
116	bcm6345_reset->rcdev.nr_resets = BCM6345_RESET_NUM;
117
118	return devm_reset_controller_register(&pdev->dev,
119					      &bcm6345_reset->rcdev);
120}
121
122static const struct of_device_id bcm6345_reset_of_match[] = {
123	{ .compatible = "brcm,bcm6345-reset" },
124	{ /* sentinel */ },
125};
126
127static struct platform_driver bcm6345_reset_driver = {
128	.probe = bcm6345_reset_probe,
129	.driver	= {
130		.name = "bcm6345-reset",
131		.of_match_table = bcm6345_reset_of_match,
132		.suppress_bind_attrs = true,
133	},
134};
135builtin_platform_driver(bcm6345_reset_driver);