Merge tag 'arm64-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux
[linux-2.6-block.git] / drivers / hwspinlock / omap_hwspinlock.c
1 /*
2  * OMAP hardware spinlock driver
3  *
4  * Copyright (C) 2010-2015 Texas Instruments Incorporated - http://www.ti.com
5  *
6  * Contact: Simon Que <sque@ti.com>
7  *          Hari Kanigeri <h-kanigeri2@ti.com>
8  *          Ohad Ben-Cohen <ohad@wizery.com>
9  *
10  * This program is free software; you can redistribute it and/or
11  * modify it under the terms of the GNU General Public License
12  * version 2 as published by the Free Software Foundation.
13  *
14  * This program is distributed in the hope that it will be useful, but
15  * WITHOUT ANY WARRANTY; without even the implied warranty of
16  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
17  * General Public License for more details.
18  */
19
20 #include <linux/kernel.h>
21 #include <linux/module.h>
22 #include <linux/device.h>
23 #include <linux/delay.h>
24 #include <linux/io.h>
25 #include <linux/bitops.h>
26 #include <linux/pm_runtime.h>
27 #include <linux/slab.h>
28 #include <linux/spinlock.h>
29 #include <linux/hwspinlock.h>
30 #include <linux/of.h>
31 #include <linux/platform_device.h>
32
33 #include "hwspinlock_internal.h"
34
35 /* Spinlock register offsets */
36 #define SYSSTATUS_OFFSET                0x0014
37 #define LOCK_BASE_OFFSET                0x0800
38
39 #define SPINLOCK_NUMLOCKS_BIT_OFFSET    (24)
40
41 /* Possible values of SPINLOCK_LOCK_REG */
42 #define SPINLOCK_NOTTAKEN               (0)     /* free */
43 #define SPINLOCK_TAKEN                  (1)     /* locked */
44
45 static int omap_hwspinlock_trylock(struct hwspinlock *lock)
46 {
47         void __iomem *lock_addr = lock->priv;
48
49         /* attempt to acquire the lock by reading its value */
50         return (SPINLOCK_NOTTAKEN == readl(lock_addr));
51 }
52
53 static void omap_hwspinlock_unlock(struct hwspinlock *lock)
54 {
55         void __iomem *lock_addr = lock->priv;
56
57         /* release the lock by writing 0 to it */
58         writel(SPINLOCK_NOTTAKEN, lock_addr);
59 }
60
61 /*
62  * relax the OMAP interconnect while spinning on it.
63  *
64  * The specs recommended that the retry delay time will be
65  * just over half of the time that a requester would be
66  * expected to hold the lock.
67  *
68  * The number below is taken from an hardware specs example,
69  * obviously it is somewhat arbitrary.
70  */
71 static void omap_hwspinlock_relax(struct hwspinlock *lock)
72 {
73         ndelay(50);
74 }
75
76 static const struct hwspinlock_ops omap_hwspinlock_ops = {
77         .trylock = omap_hwspinlock_trylock,
78         .unlock = omap_hwspinlock_unlock,
79         .relax = omap_hwspinlock_relax,
80 };
81
82 static int omap_hwspinlock_probe(struct platform_device *pdev)
83 {
84         struct device_node *node = pdev->dev.of_node;
85         struct hwspinlock_device *bank;
86         struct hwspinlock *hwlock;
87         struct resource *res;
88         void __iomem *io_base;
89         int num_locks, i, ret;
90         /* Only a single hwspinlock block device is supported */
91         int base_id = 0;
92
93         if (!node)
94                 return -ENODEV;
95
96         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
97         if (!res)
98                 return -ENODEV;
99
100         io_base = ioremap(res->start, resource_size(res));
101         if (!io_base)
102                 return -ENOMEM;
103
104         /*
105          * make sure the module is enabled and clocked before reading
106          * the module SYSSTATUS register
107          */
108         pm_runtime_enable(&pdev->dev);
109         ret = pm_runtime_get_sync(&pdev->dev);
110         if (ret < 0) {
111                 pm_runtime_put_noidle(&pdev->dev);
112                 goto iounmap_base;
113         }
114
115         /* Determine number of locks */
116         i = readl(io_base + SYSSTATUS_OFFSET);
117         i >>= SPINLOCK_NUMLOCKS_BIT_OFFSET;
118
119         /*
120          * runtime PM will make sure the clock of this module is
121          * enabled again iff at least one lock is requested
122          */
123         ret = pm_runtime_put(&pdev->dev);
124         if (ret < 0)
125                 goto iounmap_base;
126
127         /* one of the four lsb's must be set, and nothing else */
128         if (hweight_long(i & 0xf) != 1 || i > 8) {
129                 ret = -EINVAL;
130                 goto iounmap_base;
131         }
132
133         num_locks = i * 32; /* actual number of locks in this device */
134
135         bank = kzalloc(sizeof(*bank) + num_locks * sizeof(*hwlock), GFP_KERNEL);
136         if (!bank) {
137                 ret = -ENOMEM;
138                 goto iounmap_base;
139         }
140
141         platform_set_drvdata(pdev, bank);
142
143         for (i = 0, hwlock = &bank->lock[0]; i < num_locks; i++, hwlock++)
144                 hwlock->priv = io_base + LOCK_BASE_OFFSET + sizeof(u32) * i;
145
146         ret = hwspin_lock_register(bank, &pdev->dev, &omap_hwspinlock_ops,
147                                                 base_id, num_locks);
148         if (ret)
149                 goto reg_fail;
150
151         return 0;
152
153 reg_fail:
154         kfree(bank);
155 iounmap_base:
156         pm_runtime_disable(&pdev->dev);
157         iounmap(io_base);
158         return ret;
159 }
160
161 static int omap_hwspinlock_remove(struct platform_device *pdev)
162 {
163         struct hwspinlock_device *bank = platform_get_drvdata(pdev);
164         void __iomem *io_base = bank->lock[0].priv - LOCK_BASE_OFFSET;
165         int ret;
166
167         ret = hwspin_lock_unregister(bank);
168         if (ret) {
169                 dev_err(&pdev->dev, "%s failed: %d\n", __func__, ret);
170                 return ret;
171         }
172
173         pm_runtime_disable(&pdev->dev);
174         iounmap(io_base);
175         kfree(bank);
176
177         return 0;
178 }
179
180 static const struct of_device_id omap_hwspinlock_of_match[] = {
181         { .compatible = "ti,omap4-hwspinlock", },
182         { /* end */ },
183 };
184 MODULE_DEVICE_TABLE(of, omap_hwspinlock_of_match);
185
186 static struct platform_driver omap_hwspinlock_driver = {
187         .probe          = omap_hwspinlock_probe,
188         .remove         = omap_hwspinlock_remove,
189         .driver         = {
190                 .name   = "omap_hwspinlock",
191                 .of_match_table = of_match_ptr(omap_hwspinlock_of_match),
192         },
193 };
194
195 static int __init omap_hwspinlock_init(void)
196 {
197         return platform_driver_register(&omap_hwspinlock_driver);
198 }
199 /* board init code might need to reserve hwspinlocks for predefined purposes */
200 postcore_initcall(omap_hwspinlock_init);
201
202 static void __exit omap_hwspinlock_exit(void)
203 {
204         platform_driver_unregister(&omap_hwspinlock_driver);
205 }
206 module_exit(omap_hwspinlock_exit);
207
208 MODULE_LICENSE("GPL v2");
209 MODULE_DESCRIPTION("Hardware spinlock driver for OMAP");
210 MODULE_AUTHOR("Simon Que <sque@ti.com>");
211 MODULE_AUTHOR("Hari Kanigeri <h-kanigeri2@ti.com>");
212 MODULE_AUTHOR("Ohad Ben-Cohen <ohad@wizery.com>");