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(addr: bcm6345_reset->base);
40 if (assert)
41 val &= ~BIT(id);
42 else
43 val |= BIT(id);
44 __raw_writel(val, addr: bcm6345_reset->base);
45 spin_unlock_irqrestore(lock: &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, assert: 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, assert: false);
60}
61
62static int bcm6345_reset_reset(struct reset_controller_dev *rcdev,
63 unsigned long id)
64{
65 bcm6345_reset_update(rcdev, id, assert: true);
66 usleep_range(BCM6345_RESET_SLEEP_MIN_US,
67 BCM6345_RESET_SLEEP_MAX_US);
68
69 bcm6345_reset_update(rcdev, id, assert: 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(addr: 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(dev: &pdev->dev,
101 size: sizeof(*bcm6345_reset), GFP_KERNEL);
102 if (!bcm6345_reset)
103 return -ENOMEM;
104
105 bcm6345_reset->base = devm_platform_ioremap_resource(pdev, index: 0);
106 if (IS_ERR(ptr: bcm6345_reset->base))
107 return PTR_ERR(ptr: 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(dev: &pdev->dev,
117 rcdev: &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

source code of linux/drivers/reset/reset-bcm6345.c