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 	size_t array_size;
77 	int i, ret;
78 
79 	io_base = devm_platform_ioremap_resource(pdev, 0);
80 	if (IS_ERR(io_base))
81 		return PTR_ERR(io_base);
82 
83 	array_size = STM32_MUTEX_NUM_LOCKS * sizeof(struct hwspinlock);
84 	hw = devm_kzalloc(dev, sizeof(*hw) + array_size, GFP_KERNEL);
85 	if (!hw)
86 		return -ENOMEM;
87 
88 	hw->clk = devm_clk_get(dev, "hsem");
89 	if (IS_ERR(hw->clk))
90 		return PTR_ERR(hw->clk);
91 
92 	ret = clk_prepare_enable(hw->clk);
93 	if (ret) {
94 		dev_err(dev, "Failed to prepare_enable clock\n");
95 		return ret;
96 	}
97 
98 	platform_set_drvdata(pdev, hw);
99 
100 	pm_runtime_get_noresume(dev);
101 	pm_runtime_set_active(dev);
102 	pm_runtime_enable(dev);
103 	pm_runtime_put(dev);
104 
105 	ret = devm_add_action_or_reset(dev, stm32_hwspinlock_disable_clk, pdev);
106 	if (ret) {
107 		dev_err(dev, "Failed to register action\n");
108 		return ret;
109 	}
110 
111 	for (i = 0; i < STM32_MUTEX_NUM_LOCKS; i++)
112 		hw->bank.lock[i].priv = io_base + i * sizeof(u32);
113 
114 	ret = devm_hwspin_lock_register(dev, &hw->bank, &stm32_hwspinlock_ops,
115 					0, STM32_MUTEX_NUM_LOCKS);
116 
117 	if (ret)
118 		dev_err(dev, "Failed to register hwspinlock\n");
119 
120 	return ret;
121 }
122 
123 static int __maybe_unused stm32_hwspinlock_runtime_suspend(struct device *dev)
124 {
125 	struct stm32_hwspinlock *hw = dev_get_drvdata(dev);
126 
127 	clk_disable_unprepare(hw->clk);
128 
129 	return 0;
130 }
131 
132 static int __maybe_unused stm32_hwspinlock_runtime_resume(struct device *dev)
133 {
134 	struct stm32_hwspinlock *hw = dev_get_drvdata(dev);
135 
136 	clk_prepare_enable(hw->clk);
137 
138 	return 0;
139 }
140 
141 static const struct dev_pm_ops stm32_hwspinlock_pm_ops = {
142 	SET_RUNTIME_PM_OPS(stm32_hwspinlock_runtime_suspend,
143 			   stm32_hwspinlock_runtime_resume,
144 			   NULL)
145 };
146 
147 static const struct of_device_id stm32_hwpinlock_ids[] = {
148 	{ .compatible = "st,stm32-hwspinlock", },
149 	{},
150 };
151 MODULE_DEVICE_TABLE(of, stm32_hwpinlock_ids);
152 
153 static struct platform_driver stm32_hwspinlock_driver = {
154 	.probe		= stm32_hwspinlock_probe,
155 	.driver		= {
156 		.name	= "stm32_hwspinlock",
157 		.of_match_table = stm32_hwpinlock_ids,
158 		.pm	= &stm32_hwspinlock_pm_ops,
159 	},
160 };
161 
162 static int __init stm32_hwspinlock_init(void)
163 {
164 	return platform_driver_register(&stm32_hwspinlock_driver);
165 }
166 /* board init code might need to reserve hwspinlocks for predefined purposes */
167 postcore_initcall(stm32_hwspinlock_init);
168 
169 static void __exit stm32_hwspinlock_exit(void)
170 {
171 	platform_driver_unregister(&stm32_hwspinlock_driver);
172 }
173 module_exit(stm32_hwspinlock_exit);
174 
175 MODULE_LICENSE("GPL v2");
176 MODULE_DESCRIPTION("Hardware spinlock driver for STM32 SoCs");
177 MODULE_AUTHOR("Benjamin Gaignard <benjamin.gaignard@st.com>");
178