1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * OMAP hardware spinlock driver
4  *
5  * Copyright (C) 2010-2015 Texas Instruments Incorporated - http://www.ti.com
6  *
7  * Contact: Simon Que <sque@ti.com>
8  *          Hari Kanigeri <h-kanigeri2@ti.com>
9  *          Ohad Ben-Cohen <ohad@wizery.com>
10  */
11 
12 #include <linux/kernel.h>
13 #include <linux/module.h>
14 #include <linux/device.h>
15 #include <linux/delay.h>
16 #include <linux/io.h>
17 #include <linux/bitops.h>
18 #include <linux/pm_runtime.h>
19 #include <linux/slab.h>
20 #include <linux/spinlock.h>
21 #include <linux/hwspinlock.h>
22 #include <linux/of.h>
23 #include <linux/platform_device.h>
24 
25 #include "hwspinlock_internal.h"
26 
27 /* Spinlock register offsets */
28 #define SYSSTATUS_OFFSET		0x0014
29 #define LOCK_BASE_OFFSET		0x0800
30 
31 #define SPINLOCK_NUMLOCKS_BIT_OFFSET	(24)
32 
33 /* Possible values of SPINLOCK_LOCK_REG */
34 #define SPINLOCK_NOTTAKEN		(0)	/* free */
35 #define SPINLOCK_TAKEN			(1)	/* locked */
36 
37 static int omap_hwspinlock_trylock(struct hwspinlock *lock)
38 {
39 	void __iomem *lock_addr = lock->priv;
40 
41 	/* attempt to acquire the lock by reading its value */
42 	return (SPINLOCK_NOTTAKEN == readl(lock_addr));
43 }
44 
45 static void omap_hwspinlock_unlock(struct hwspinlock *lock)
46 {
47 	void __iomem *lock_addr = lock->priv;
48 
49 	/* release the lock by writing 0 to it */
50 	writel(SPINLOCK_NOTTAKEN, lock_addr);
51 }
52 
53 /*
54  * relax the OMAP interconnect while spinning on it.
55  *
56  * The specs recommended that the retry delay time will be
57  * just over half of the time that a requester would be
58  * expected to hold the lock.
59  *
60  * The number below is taken from an hardware specs example,
61  * obviously it is somewhat arbitrary.
62  */
63 static void omap_hwspinlock_relax(struct hwspinlock *lock)
64 {
65 	ndelay(50);
66 }
67 
68 static const struct hwspinlock_ops omap_hwspinlock_ops = {
69 	.trylock = omap_hwspinlock_trylock,
70 	.unlock = omap_hwspinlock_unlock,
71 	.relax = omap_hwspinlock_relax,
72 };
73 
74 static int omap_hwspinlock_probe(struct platform_device *pdev)
75 {
76 	struct device_node *node = pdev->dev.of_node;
77 	struct hwspinlock_device *bank;
78 	struct hwspinlock *hwlock;
79 	struct resource *res;
80 	void __iomem *io_base;
81 	int num_locks, i, ret;
82 	/* Only a single hwspinlock block device is supported */
83 	int base_id = 0;
84 
85 	if (!node)
86 		return -ENODEV;
87 
88 	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
89 	if (!res)
90 		return -ENODEV;
91 
92 	io_base = ioremap(res->start, resource_size(res));
93 	if (!io_base)
94 		return -ENOMEM;
95 
96 	/*
97 	 * make sure the module is enabled and clocked before reading
98 	 * the module SYSSTATUS register
99 	 */
100 	pm_runtime_enable(&pdev->dev);
101 	ret = pm_runtime_get_sync(&pdev->dev);
102 	if (ret < 0) {
103 		pm_runtime_put_noidle(&pdev->dev);
104 		goto iounmap_base;
105 	}
106 
107 	/* Determine number of locks */
108 	i = readl(io_base + SYSSTATUS_OFFSET);
109 	i >>= SPINLOCK_NUMLOCKS_BIT_OFFSET;
110 
111 	/*
112 	 * runtime PM will make sure the clock of this module is
113 	 * enabled again iff at least one lock is requested
114 	 */
115 	ret = pm_runtime_put(&pdev->dev);
116 	if (ret < 0)
117 		goto iounmap_base;
118 
119 	/* one of the four lsb's must be set, and nothing else */
120 	if (hweight_long(i & 0xf) != 1 || i > 8) {
121 		ret = -EINVAL;
122 		goto iounmap_base;
123 	}
124 
125 	num_locks = i * 32; /* actual number of locks in this device */
126 
127 	bank = kzalloc(struct_size(bank, lock, num_locks), GFP_KERNEL);
128 	if (!bank) {
129 		ret = -ENOMEM;
130 		goto iounmap_base;
131 	}
132 
133 	platform_set_drvdata(pdev, bank);
134 
135 	for (i = 0, hwlock = &bank->lock[0]; i < num_locks; i++, hwlock++)
136 		hwlock->priv = io_base + LOCK_BASE_OFFSET + sizeof(u32) * i;
137 
138 	ret = hwspin_lock_register(bank, &pdev->dev, &omap_hwspinlock_ops,
139 						base_id, num_locks);
140 	if (ret)
141 		goto reg_fail;
142 
143 	return 0;
144 
145 reg_fail:
146 	kfree(bank);
147 iounmap_base:
148 	pm_runtime_disable(&pdev->dev);
149 	iounmap(io_base);
150 	return ret;
151 }
152 
153 static int omap_hwspinlock_remove(struct platform_device *pdev)
154 {
155 	struct hwspinlock_device *bank = platform_get_drvdata(pdev);
156 	void __iomem *io_base = bank->lock[0].priv - LOCK_BASE_OFFSET;
157 	int ret;
158 
159 	ret = hwspin_lock_unregister(bank);
160 	if (ret) {
161 		dev_err(&pdev->dev, "%s failed: %d\n", __func__, ret);
162 		return ret;
163 	}
164 
165 	pm_runtime_disable(&pdev->dev);
166 	iounmap(io_base);
167 	kfree(bank);
168 
169 	return 0;
170 }
171 
172 static const struct of_device_id omap_hwspinlock_of_match[] = {
173 	{ .compatible = "ti,omap4-hwspinlock", },
174 	{ /* end */ },
175 };
176 MODULE_DEVICE_TABLE(of, omap_hwspinlock_of_match);
177 
178 static struct platform_driver omap_hwspinlock_driver = {
179 	.probe		= omap_hwspinlock_probe,
180 	.remove		= omap_hwspinlock_remove,
181 	.driver		= {
182 		.name	= "omap_hwspinlock",
183 		.of_match_table = of_match_ptr(omap_hwspinlock_of_match),
184 	},
185 };
186 
187 static int __init omap_hwspinlock_init(void)
188 {
189 	return platform_driver_register(&omap_hwspinlock_driver);
190 }
191 /* board init code might need to reserve hwspinlocks for predefined purposes */
192 postcore_initcall(omap_hwspinlock_init);
193 
194 static void __exit omap_hwspinlock_exit(void)
195 {
196 	platform_driver_unregister(&omap_hwspinlock_driver);
197 }
198 module_exit(omap_hwspinlock_exit);
199 
200 MODULE_LICENSE("GPL v2");
201 MODULE_DESCRIPTION("Hardware spinlock driver for OMAP");
202 MODULE_AUTHOR("Simon Que <sque@ti.com>");
203 MODULE_AUTHOR("Hari Kanigeri <h-kanigeri2@ti.com>");
204 MODULE_AUTHOR("Ohad Ben-Cohen <ohad@wizery.com>");
205