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 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 
71 static 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 
121 static 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 
130 static 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 
139 static 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 
145 static const struct of_device_id stm32_hwpinlock_ids[] = {
146 	{ .compatible = "st,stm32-hwspinlock", },
147 	{},
148 };
149 MODULE_DEVICE_TABLE(of, stm32_hwpinlock_ids);
150 
151 static 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 
160 static 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 */
165 postcore_initcall(stm32_hwspinlock_init);
166 
167 static void __exit stm32_hwspinlock_exit(void)
168 {
169 	platform_driver_unregister(&stm32_hwspinlock_driver);
170 }
171 module_exit(stm32_hwspinlock_exit);
172 
173 MODULE_LICENSE("GPL v2");
174 MODULE_DESCRIPTION("Hardware spinlock driver for STM32 SoCs");
175 MODULE_AUTHOR("Benjamin Gaignard <benjamin.gaignard@st.com>");
176