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 
23 struct stm32_hwspinlock {
24 	struct clk *clk;
25 	struct hwspinlock_device bank;
26 };
27 
28 static 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 
39 static 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 
46 static void stm32_hwspinlock_relax(struct hwspinlock *lock)
47 {
48 	ndelay(50);
49 }
50 
51 static const struct hwspinlock_ops stm32_hwspinlock_ops = {
52 	.trylock	= stm32_hwspinlock_trylock,
53 	.unlock		= stm32_hwspinlock_unlock,
54 	.relax		= stm32_hwspinlock_relax,
55 };
56 
57 static int stm32_hwspinlock_probe(struct platform_device *pdev)
58 {
59 	struct stm32_hwspinlock *hw;
60 	void __iomem *io_base;
61 	size_t array_size;
62 	int i, ret;
63 
64 	io_base = devm_platform_ioremap_resource(pdev, 0);
65 	if (IS_ERR(io_base))
66 		return PTR_ERR(io_base);
67 
68 	array_size = STM32_MUTEX_NUM_LOCKS * sizeof(struct hwspinlock);
69 	hw = devm_kzalloc(&pdev->dev, sizeof(*hw) + array_size, GFP_KERNEL);
70 	if (!hw)
71 		return -ENOMEM;
72 
73 	hw->clk = devm_clk_get(&pdev->dev, "hsem");
74 	if (IS_ERR(hw->clk))
75 		return PTR_ERR(hw->clk);
76 
77 	for (i = 0; i < STM32_MUTEX_NUM_LOCKS; i++)
78 		hw->bank.lock[i].priv = io_base + i * sizeof(u32);
79 
80 	platform_set_drvdata(pdev, hw);
81 	pm_runtime_enable(&pdev->dev);
82 
83 	ret = hwspin_lock_register(&hw->bank, &pdev->dev, &stm32_hwspinlock_ops,
84 				   0, STM32_MUTEX_NUM_LOCKS);
85 
86 	if (ret)
87 		pm_runtime_disable(&pdev->dev);
88 
89 	return ret;
90 }
91 
92 static int stm32_hwspinlock_remove(struct platform_device *pdev)
93 {
94 	struct stm32_hwspinlock *hw = platform_get_drvdata(pdev);
95 	int ret;
96 
97 	ret = hwspin_lock_unregister(&hw->bank);
98 	if (ret)
99 		dev_err(&pdev->dev, "%s failed: %d\n", __func__, ret);
100 
101 	pm_runtime_disable(&pdev->dev);
102 
103 	return 0;
104 }
105 
106 static int __maybe_unused stm32_hwspinlock_runtime_suspend(struct device *dev)
107 {
108 	struct stm32_hwspinlock *hw = dev_get_drvdata(dev);
109 
110 	clk_disable_unprepare(hw->clk);
111 
112 	return 0;
113 }
114 
115 static int __maybe_unused stm32_hwspinlock_runtime_resume(struct device *dev)
116 {
117 	struct stm32_hwspinlock *hw = dev_get_drvdata(dev);
118 
119 	clk_prepare_enable(hw->clk);
120 
121 	return 0;
122 }
123 
124 static const struct dev_pm_ops stm32_hwspinlock_pm_ops = {
125 	SET_RUNTIME_PM_OPS(stm32_hwspinlock_runtime_suspend,
126 			   stm32_hwspinlock_runtime_resume,
127 			   NULL)
128 };
129 
130 static const struct of_device_id stm32_hwpinlock_ids[] = {
131 	{ .compatible = "st,stm32-hwspinlock", },
132 	{},
133 };
134 MODULE_DEVICE_TABLE(of, stm32_hwpinlock_ids);
135 
136 static struct platform_driver stm32_hwspinlock_driver = {
137 	.probe		= stm32_hwspinlock_probe,
138 	.remove		= stm32_hwspinlock_remove,
139 	.driver		= {
140 		.name	= "stm32_hwspinlock",
141 		.of_match_table = stm32_hwpinlock_ids,
142 		.pm	= &stm32_hwspinlock_pm_ops,
143 	},
144 };
145 
146 static int __init stm32_hwspinlock_init(void)
147 {
148 	return platform_driver_register(&stm32_hwspinlock_driver);
149 }
150 /* board init code might need to reserve hwspinlocks for predefined purposes */
151 postcore_initcall(stm32_hwspinlock_init);
152 
153 static void __exit stm32_hwspinlock_exit(void)
154 {
155 	platform_driver_unregister(&stm32_hwspinlock_driver);
156 }
157 module_exit(stm32_hwspinlock_exit);
158 
159 MODULE_LICENSE("GPL v2");
160 MODULE_DESCRIPTION("Hardware spinlock driver for STM32 SoCs");
161 MODULE_AUTHOR("Benjamin Gaignard <benjamin.gaignard@st.com>");
162