Root/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
44static int omap_hwspinlock_trylock(struct hwspinlock *lock)
45{
46    void __iomem *lock_addr = lock->priv;
47
48    /* attempt to acquire the lock by reading its value */
49    return (SPINLOCK_NOTTAKEN == readl(lock_addr));
50}
51
52static void omap_hwspinlock_unlock(struct hwspinlock *lock)
53{
54    void __iomem *lock_addr = lock->priv;
55
56    /* release the lock by writing 0 to it */
57    writel(SPINLOCK_NOTTAKEN, lock_addr);
58}
59
60/*
61 * relax the OMAP interconnect while spinning on it.
62 *
63 * The specs recommended that the retry delay time will be
64 * just over half of the time that a requester would be
65 * expected to hold the lock.
66 *
67 * The number below is taken from an hardware specs example,
68 * obviously it is somewhat arbitrary.
69 */
70static void omap_hwspinlock_relax(struct hwspinlock *lock)
71{
72    ndelay(50);
73}
74
75static const struct hwspinlock_ops omap_hwspinlock_ops = {
76    .trylock = omap_hwspinlock_trylock,
77    .unlock = omap_hwspinlock_unlock,
78    .relax = omap_hwspinlock_relax,
79};
80
81static int __devinit omap_hwspinlock_probe(struct platform_device *pdev)
82{
83    struct hwspinlock_pdata *pdata = pdev->dev.platform_data;
84    struct hwspinlock_device *bank;
85    struct hwspinlock *hwlock;
86    struct resource *res;
87    void __iomem *io_base;
88    int num_locks, i, ret;
89
90    if (!pdata)
91        return -ENODEV;
92
93    res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
94    if (!res)
95        return -ENODEV;
96
97    io_base = ioremap(res->start, resource_size(res));
98    if (!io_base)
99        return -ENOMEM;
100
101    /* Determine number of locks */
102    i = readl(io_base + SYSSTATUS_OFFSET);
103    i >>= SPINLOCK_NUMLOCKS_BIT_OFFSET;
104
105    /* one of the four lsb's must be set, and nothing else */
106    if (hweight_long(i & 0xf) != 1 || i > 8) {
107        ret = -EINVAL;
108        goto iounmap_base;
109    }
110
111    num_locks = i * 32; /* actual number of locks in this device */
112
113    bank = kzalloc(sizeof(*bank) + num_locks * sizeof(*hwlock), GFP_KERNEL);
114    if (!bank) {
115        ret = -ENOMEM;
116        goto iounmap_base;
117    }
118
119    platform_set_drvdata(pdev, bank);
120
121    for (i = 0, hwlock = &bank->lock[0]; i < num_locks; i++, hwlock++)
122        hwlock->priv = io_base + LOCK_BASE_OFFSET + sizeof(u32) * i;
123
124    /*
125     * runtime PM will make sure the clock of this module is
126     * enabled iff at least one lock is requested
127     */
128    pm_runtime_enable(&pdev->dev);
129
130    ret = hwspin_lock_register(bank, &pdev->dev, &omap_hwspinlock_ops,
131                        pdata->base_id, num_locks);
132    if (ret)
133        goto reg_fail;
134
135    return 0;
136
137reg_fail:
138    pm_runtime_disable(&pdev->dev);
139    kfree(bank);
140iounmap_base:
141    iounmap(io_base);
142    return ret;
143}
144
145static int __devexit omap_hwspinlock_remove(struct platform_device *pdev)
146{
147    struct hwspinlock_device *bank = platform_get_drvdata(pdev);
148    void __iomem *io_base = bank->lock[0].priv - LOCK_BASE_OFFSET;
149    int ret;
150
151    ret = hwspin_lock_unregister(bank);
152    if (ret) {
153        dev_err(&pdev->dev, "%s failed: %d\n", __func__, ret);
154        return ret;
155    }
156
157    pm_runtime_disable(&pdev->dev);
158    iounmap(io_base);
159    kfree(bank);
160
161    return 0;
162}
163
164static struct platform_driver omap_hwspinlock_driver = {
165    .probe = omap_hwspinlock_probe,
166    .remove = __devexit_p(omap_hwspinlock_remove),
167    .driver = {
168        .name = "omap_hwspinlock",
169        .owner = THIS_MODULE,
170    },
171};
172
173static int __init omap_hwspinlock_init(void)
174{
175    return platform_driver_register(&omap_hwspinlock_driver);
176}
177/* board init code might need to reserve hwspinlocks for predefined purposes */
178postcore_initcall(omap_hwspinlock_init);
179
180static void __exit omap_hwspinlock_exit(void)
181{
182    platform_driver_unregister(&omap_hwspinlock_driver);
183}
184module_exit(omap_hwspinlock_exit);
185
186MODULE_LICENSE("GPL v2");
187MODULE_DESCRIPTION("Hardware spinlock driver for OMAP");
188MODULE_AUTHOR("Simon Que <sque@ti.com>");
189MODULE_AUTHOR("Hari Kanigeri <h-kanigeri2@ti.com>");
190MODULE_AUTHOR("Ohad Ben-Cohen <ohad@wizery.com>");
191

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