a8f02734c026f0691a0e7b3847af07429bb937bd
[linux-2.6.git] / drivers / hwspinlock / omap_hwspinlock.c
1 /*
2  * OMAP hardware spinlock driver
3  *
4  * Copyright (C) 2010 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/platform_device.h>
31
32 #include "hwspinlock_internal.h"
33
34 /* Spinlock register offsets */
35 #define SYSSTATUS_OFFSET                0x0014
36 #define LOCK_BASE_OFFSET                0x0800
37
38 #define SPINLOCK_NUMLOCKS_BIT_OFFSET    (24)
39
40 /* Possible values of SPINLOCK_LOCK_REG */
41 #define SPINLOCK_NOTTAKEN               (0)     /* free */
42 #define SPINLOCK_TAKEN                  (1)     /* locked */
43
44 #define to_omap_hwspinlock(lock)        \
45         container_of(lock, struct omap_hwspinlock, lock)
46
47 struct omap_hwspinlock {
48         struct hwspinlock lock;
49         void __iomem *addr;
50 };
51
52 struct omap_hwspinlock_state {
53         int num_locks;                  /* Total number of locks in system */
54         void __iomem *io_base;          /* Mapped base address */
55 };
56
57 static int omap_hwspinlock_trylock(struct hwspinlock *lock)
58 {
59         struct omap_hwspinlock *omap_lock = to_omap_hwspinlock(lock);
60
61         /* attempt to acquire the lock by reading its value */
62         return (SPINLOCK_NOTTAKEN == readl(omap_lock->addr));
63 }
64
65 static void omap_hwspinlock_unlock(struct hwspinlock *lock)
66 {
67         struct omap_hwspinlock *omap_lock = to_omap_hwspinlock(lock);
68
69         /* release the lock by writing 0 to it */
70         writel(SPINLOCK_NOTTAKEN, omap_lock->addr);
71 }
72
73 /*
74  * relax the OMAP interconnect while spinning on it.
75  *
76  * The specs recommended that the retry delay time will be
77  * just over half of the time that a requester would be
78  * expected to hold the lock.
79  *
80  * The number below is taken from an hardware specs example,
81  * obviously it is somewhat arbitrary.
82  */
83 static void omap_hwspinlock_relax(struct hwspinlock *lock)
84 {
85         ndelay(50);
86 }
87
88 static const struct hwspinlock_ops omap_hwspinlock_ops = {
89         .trylock = omap_hwspinlock_trylock,
90         .unlock = omap_hwspinlock_unlock,
91         .relax = omap_hwspinlock_relax,
92 };
93
94 static int __devinit omap_hwspinlock_probe(struct platform_device *pdev)
95 {
96         struct omap_hwspinlock *omap_lock;
97         struct omap_hwspinlock_state *state;
98         struct hwspinlock *lock;
99         struct resource *res;
100         void __iomem *io_base;
101         int i, ret;
102
103         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
104         if (!res)
105                 return -ENODEV;
106
107         state = kzalloc(sizeof(*state), GFP_KERNEL);
108         if (!state)
109                 return -ENOMEM;
110
111         io_base = ioremap(res->start, resource_size(res));
112         if (!io_base) {
113                 ret = -ENOMEM;
114                 goto free_state;
115         }
116
117         /* Determine number of locks */
118         i = readl(io_base + SYSSTATUS_OFFSET);
119         i >>= SPINLOCK_NUMLOCKS_BIT_OFFSET;
120
121         /* one of the four lsb's must be set, and nothing else */
122         if (hweight_long(i & 0xf) != 1 || i > 8) {
123                 ret = -EINVAL;
124                 goto iounmap_base;
125         }
126
127         state->num_locks = i * 32;
128         state->io_base = io_base;
129
130         platform_set_drvdata(pdev, state);
131
132         /*
133          * runtime PM will make sure the clock of this module is
134          * enabled iff at least one lock is requested
135          */
136         pm_runtime_enable(&pdev->dev);
137
138         for (i = 0; i < state->num_locks; i++) {
139                 omap_lock = kzalloc(sizeof(*omap_lock), GFP_KERNEL);
140                 if (!omap_lock) {
141                         ret = -ENOMEM;
142                         goto free_locks;
143                 }
144
145                 omap_lock->lock.dev = &pdev->dev;
146                 omap_lock->lock.owner = THIS_MODULE;
147                 omap_lock->lock.id = i;
148                 omap_lock->lock.ops = &omap_hwspinlock_ops;
149                 omap_lock->addr = io_base + LOCK_BASE_OFFSET + sizeof(u32) * i;
150
151                 ret = hwspin_lock_register(&omap_lock->lock);
152                 if (ret) {
153                         kfree(omap_lock);
154                         goto free_locks;
155                 }
156         }
157
158         return 0;
159
160 free_locks:
161         while (--i >= 0) {
162                 lock = hwspin_lock_unregister(i);
163                 /* this should't happen, but let's give our best effort */
164                 if (!lock) {
165                         dev_err(&pdev->dev, "%s: cleanups failed\n", __func__);
166                         continue;
167                 }
168                 omap_lock = to_omap_hwspinlock(lock);
169                 kfree(omap_lock);
170         }
171         pm_runtime_disable(&pdev->dev);
172 iounmap_base:
173         iounmap(io_base);
174 free_state:
175         kfree(state);
176         return ret;
177 }
178
179 static int omap_hwspinlock_remove(struct platform_device *pdev)
180 {
181         struct omap_hwspinlock_state *state = platform_get_drvdata(pdev);
182         struct hwspinlock *lock;
183         struct omap_hwspinlock *omap_lock;
184         int i;
185
186         for (i = 0; i < state->num_locks; i++) {
187                 lock = hwspin_lock_unregister(i);
188                 /* this shouldn't happen at this point. if it does, at least
189                  * don't continue with the remove */
190                 if (!lock) {
191                         dev_err(&pdev->dev, "%s: failed on %d\n", __func__, i);
192                         return -EBUSY;
193                 }
194
195                 omap_lock = to_omap_hwspinlock(lock);
196                 kfree(omap_lock);
197         }
198
199         pm_runtime_disable(&pdev->dev);
200         iounmap(state->io_base);
201         kfree(state);
202
203         return 0;
204 }
205
206 static struct platform_driver omap_hwspinlock_driver = {
207         .probe          = omap_hwspinlock_probe,
208         .remove         = omap_hwspinlock_remove,
209         .driver         = {
210                 .name   = "omap_hwspinlock",
211         },
212 };
213
214 static int __init omap_hwspinlock_init(void)
215 {
216         return platform_driver_register(&omap_hwspinlock_driver);
217 }
218 /* board init code might need to reserve hwspinlocks for predefined purposes */
219 postcore_initcall(omap_hwspinlock_init);
220
221 static void __exit omap_hwspinlock_exit(void)
222 {
223         platform_driver_unregister(&omap_hwspinlock_driver);
224 }
225 module_exit(omap_hwspinlock_exit);
226
227 MODULE_LICENSE("GPL v2");
228 MODULE_DESCRIPTION("Hardware spinlock driver for OMAP");
229 MODULE_AUTHOR("Simon Que <sque@ti.com>");
230 MODULE_AUTHOR("Hari Kanigeri <h-kanigeri2@ti.com>");
231 MODULE_AUTHOR("Ohad Ben-Cohen <ohad@wizery.com>");