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	bcm6345_reset->base = devm_platform_ioremap_resource(pdev, 0);
106	if (IS_ERR(bcm6345_reset->base))
107		return PTR_ERR(bcm6345_reset->base);
108
109	spin_lock_init(&bcm6345_reset->lock);
110	bcm6345_reset->rcdev.ops = &bcm6345_reset_ops;
111	bcm6345_reset->rcdev.owner = THIS_MODULE;
112	bcm6345_reset->rcdev.of_node = pdev->dev.of_node;
113	bcm6345_reset->rcdev.of_reset_n_cells = 1;
114	bcm6345_reset->rcdev.nr_resets = BCM6345_RESET_NUM;
115
116	return devm_reset_controller_register(&pdev->dev,
117					      &bcm6345_reset->rcdev);
118}
119
120static const struct of_device_id bcm6345_reset_of_match[] = {
121	{ .compatible = "brcm,bcm6345-reset" },
122	{ /* sentinel */ },
123};
124
125static struct platform_driver bcm6345_reset_driver = {
126	.probe = bcm6345_reset_probe,
127	.driver	= {
128		.name = "bcm6345-reset",
129		.of_match_table = bcm6345_reset_of_match,
130		.suppress_bind_attrs = true,
131	},
132};
133builtin_platform_driver(bcm6345_reset_driver);
134