1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Copyright (C) STMicroelectronics SA 2018
4 * Author: Benjamin Gaignard <benjamin.gaignard@st.com> for STMicroelectronics.
5 */
6
7#include <linux/clk.h>
8#include <linux/delay.h>
9#include <linux/hwspinlock.h>
10#include <linux/io.h>
11#include <linux/kernel.h>
12#include <linux/module.h>
13#include <linux/of.h>
14#include <linux/platform_device.h>
15#include <linux/pm_runtime.h>
16
17#include "hwspinlock_internal.h"
18
19#define STM32_MUTEX_COREID	BIT(8)
20#define STM32_MUTEX_LOCK_BIT	BIT(31)
21#define STM32_MUTEX_NUM_LOCKS	32
22
23struct stm32_hwspinlock {
24	struct clk *clk;
25	struct hwspinlock_device bank;
26};
27
28static int stm32_hwspinlock_trylock(struct hwspinlock *lock)
29{
30	void __iomem *lock_addr = lock->priv;
31	u32 status;
32
33	writel(STM32_MUTEX_LOCK_BIT | STM32_MUTEX_COREID, lock_addr);
34	status = readl(lock_addr);
35
36	return status == (STM32_MUTEX_LOCK_BIT | STM32_MUTEX_COREID);
37}
38
39static void stm32_hwspinlock_unlock(struct hwspinlock *lock)
40{
41	void __iomem *lock_addr = lock->priv;
42
43	writel(STM32_MUTEX_COREID, lock_addr);
44}
45
46static void stm32_hwspinlock_relax(struct hwspinlock *lock)
47{
48	ndelay(50);
49}
50
51static const struct hwspinlock_ops stm32_hwspinlock_ops = {
52	.trylock	= stm32_hwspinlock_trylock,
53	.unlock		= stm32_hwspinlock_unlock,
54	.relax		= stm32_hwspinlock_relax,
55};
56
57static void stm32_hwspinlock_disable_clk(void *data)
58{
59	struct platform_device *pdev = data;
60	struct stm32_hwspinlock *hw = platform_get_drvdata(pdev);
61	struct device *dev = &pdev->dev;
62
63	pm_runtime_get_sync(dev);
64	pm_runtime_disable(dev);
65	pm_runtime_set_suspended(dev);
66	pm_runtime_put_noidle(dev);
67
68	clk_disable_unprepare(hw->clk);
69}
70
71static int stm32_hwspinlock_probe(struct platform_device *pdev)
72{
73	struct device *dev = &pdev->dev;
74	struct stm32_hwspinlock *hw;
75	void __iomem *io_base;
76	int i, ret;
77
78	io_base = devm_platform_ioremap_resource(pdev, 0);
79	if (IS_ERR(io_base))
80		return PTR_ERR(io_base);
81
82	hw = devm_kzalloc(dev, struct_size(hw, bank.lock, STM32_MUTEX_NUM_LOCKS), GFP_KERNEL);
83	if (!hw)
84		return -ENOMEM;
85
86	hw->clk = devm_clk_get(dev, "hsem");
87	if (IS_ERR(hw->clk))
88		return PTR_ERR(hw->clk);
89
90	ret = clk_prepare_enable(hw->clk);
91	if (ret) {
92		dev_err(dev, "Failed to prepare_enable clock\n");
93		return ret;
94	}
95
96	platform_set_drvdata(pdev, hw);
97
98	pm_runtime_get_noresume(dev);
99	pm_runtime_set_active(dev);
100	pm_runtime_enable(dev);
101	pm_runtime_put(dev);
102
103	ret = devm_add_action_or_reset(dev, stm32_hwspinlock_disable_clk, pdev);
104	if (ret) {
105		dev_err(dev, "Failed to register action\n");
106		return ret;
107	}
108
109	for (i = 0; i < STM32_MUTEX_NUM_LOCKS; i++)
110		hw->bank.lock[i].priv = io_base + i * sizeof(u32);
111
112	ret = devm_hwspin_lock_register(dev, &hw->bank, &stm32_hwspinlock_ops,
113					0, STM32_MUTEX_NUM_LOCKS);
114
115	if (ret)
116		dev_err(dev, "Failed to register hwspinlock\n");
117
118	return ret;
119}
120
121static int __maybe_unused stm32_hwspinlock_runtime_suspend(struct device *dev)
122{
123	struct stm32_hwspinlock *hw = dev_get_drvdata(dev);
124
125	clk_disable_unprepare(hw->clk);
126
127	return 0;
128}
129
130static int __maybe_unused stm32_hwspinlock_runtime_resume(struct device *dev)
131{
132	struct stm32_hwspinlock *hw = dev_get_drvdata(dev);
133
134	clk_prepare_enable(hw->clk);
135
136	return 0;
137}
138
139static const struct dev_pm_ops stm32_hwspinlock_pm_ops = {
140	SET_RUNTIME_PM_OPS(stm32_hwspinlock_runtime_suspend,
141			   stm32_hwspinlock_runtime_resume,
142			   NULL)
143};
144
145static const struct of_device_id stm32_hwpinlock_ids[] = {
146	{ .compatible = "st,stm32-hwspinlock", },
147	{},
148};
149MODULE_DEVICE_TABLE(of, stm32_hwpinlock_ids);
150
151static struct platform_driver stm32_hwspinlock_driver = {
152	.probe		= stm32_hwspinlock_probe,
153	.driver		= {
154		.name	= "stm32_hwspinlock",
155		.of_match_table = stm32_hwpinlock_ids,
156		.pm	= &stm32_hwspinlock_pm_ops,
157	},
158};
159
160static int __init stm32_hwspinlock_init(void)
161{
162	return platform_driver_register(&stm32_hwspinlock_driver);
163}
164/* board init code might need to reserve hwspinlocks for predefined purposes */
165postcore_initcall(stm32_hwspinlock_init);
166
167static void __exit stm32_hwspinlock_exit(void)
168{
169	platform_driver_unregister(&stm32_hwspinlock_driver);
170}
171module_exit(stm32_hwspinlock_exit);
172
173MODULE_LICENSE("GPL v2");
174MODULE_DESCRIPTION("Hardware spinlock driver for STM32 SoCs");
175MODULE_AUTHOR("Benjamin Gaignard <benjamin.gaignard@st.com>");
176