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/hwspinlock.h>
9 #include <linux/io.h>
10 #include <linux/kernel.h>
11 #include <linux/module.h>
12 #include <linux/of.h>
13 #include <linux/platform_device.h>
14 #include <linux/pm_runtime.h>
15 
16 #include "hwspinlock_internal.h"
17 
18 #define STM32_MUTEX_COREID	BIT(8)
19 #define STM32_MUTEX_LOCK_BIT	BIT(31)
20 #define STM32_MUTEX_NUM_LOCKS	32
21 
22 struct stm32_hwspinlock {
23 	struct clk *clk;
24 	struct hwspinlock_device bank;
25 };
26 
27 static int stm32_hwspinlock_trylock(struct hwspinlock *lock)
28 {
29 	void __iomem *lock_addr = lock->priv;
30 	u32 status;
31 
32 	writel(STM32_MUTEX_LOCK_BIT | STM32_MUTEX_COREID, lock_addr);
33 	status = readl(lock_addr);
34 
35 	return status == (STM32_MUTEX_LOCK_BIT | STM32_MUTEX_COREID);
36 }
37 
38 static void stm32_hwspinlock_unlock(struct hwspinlock *lock)
39 {
40 	void __iomem *lock_addr = lock->priv;
41 
42 	writel(STM32_MUTEX_COREID, lock_addr);
43 }
44 
45 static const struct hwspinlock_ops stm32_hwspinlock_ops = {
46 	.trylock	= stm32_hwspinlock_trylock,
47 	.unlock		= stm32_hwspinlock_unlock,
48 };
49 
50 static int stm32_hwspinlock_probe(struct platform_device *pdev)
51 {
52 	struct stm32_hwspinlock *hw;
53 	void __iomem *io_base;
54 	struct resource *res;
55 	size_t array_size;
56 	int i, ret;
57 
58 	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
59 	io_base = devm_ioremap_resource(&pdev->dev, res);
60 	if (IS_ERR(io_base))
61 		return PTR_ERR(io_base);
62 
63 	array_size = STM32_MUTEX_NUM_LOCKS * sizeof(struct hwspinlock);
64 	hw = devm_kzalloc(&pdev->dev, sizeof(*hw) + array_size, GFP_KERNEL);
65 	if (!hw)
66 		return -ENOMEM;
67 
68 	hw->clk = devm_clk_get(&pdev->dev, "hsem");
69 	if (IS_ERR(hw->clk))
70 		return PTR_ERR(hw->clk);
71 
72 	for (i = 0; i < STM32_MUTEX_NUM_LOCKS; i++)
73 		hw->bank.lock[i].priv = io_base + i * sizeof(u32);
74 
75 	platform_set_drvdata(pdev, hw);
76 	pm_runtime_enable(&pdev->dev);
77 
78 	ret = hwspin_lock_register(&hw->bank, &pdev->dev, &stm32_hwspinlock_ops,
79 				   0, STM32_MUTEX_NUM_LOCKS);
80 
81 	if (ret)
82 		pm_runtime_disable(&pdev->dev);
83 
84 	return ret;
85 }
86 
87 static int stm32_hwspinlock_remove(struct platform_device *pdev)
88 {
89 	struct stm32_hwspinlock *hw = platform_get_drvdata(pdev);
90 	int ret;
91 
92 	ret = hwspin_lock_unregister(&hw->bank);
93 	if (ret)
94 		dev_err(&pdev->dev, "%s failed: %d\n", __func__, ret);
95 
96 	pm_runtime_disable(&pdev->dev);
97 
98 	return 0;
99 }
100 
101 static int __maybe_unused stm32_hwspinlock_runtime_suspend(struct device *dev)
102 {
103 	struct stm32_hwspinlock *hw = dev_get_drvdata(dev);
104 
105 	clk_disable_unprepare(hw->clk);
106 
107 	return 0;
108 }
109 
110 static int __maybe_unused stm32_hwspinlock_runtime_resume(struct device *dev)
111 {
112 	struct stm32_hwspinlock *hw = dev_get_drvdata(dev);
113 
114 	clk_prepare_enable(hw->clk);
115 
116 	return 0;
117 }
118 
119 static const struct dev_pm_ops stm32_hwspinlock_pm_ops = {
120 	SET_RUNTIME_PM_OPS(stm32_hwspinlock_runtime_suspend,
121 			   stm32_hwspinlock_runtime_resume,
122 			   NULL)
123 };
124 
125 static const struct of_device_id stm32_hwpinlock_ids[] = {
126 	{ .compatible = "st,stm32-hwspinlock", },
127 	{},
128 };
129 MODULE_DEVICE_TABLE(of, stm32_hwpinlock_ids);
130 
131 static struct platform_driver stm32_hwspinlock_driver = {
132 	.probe		= stm32_hwspinlock_probe,
133 	.remove		= stm32_hwspinlock_remove,
134 	.driver		= {
135 		.name	= "stm32_hwspinlock",
136 		.of_match_table = stm32_hwpinlock_ids,
137 		.pm	= &stm32_hwspinlock_pm_ops,
138 	},
139 };
140 
141 static int __init stm32_hwspinlock_init(void)
142 {
143 	return platform_driver_register(&stm32_hwspinlock_driver);
144 }
145 /* board init code might need to reserve hwspinlocks for predefined purposes */
146 postcore_initcall(stm32_hwspinlock_init);
147 
148 static void __exit stm32_hwspinlock_exit(void)
149 {
150 	platform_driver_unregister(&stm32_hwspinlock_driver);
151 }
152 module_exit(stm32_hwspinlock_exit);
153 
154 MODULE_LICENSE("GPL v2");
155 MODULE_DESCRIPTION("Hardware spinlock driver for STM32 SoCs");
156 MODULE_AUTHOR("Benjamin Gaignard <benjamin.gaignard@st.com>");
157