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 static 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
  52 static 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  */
  70 static void omap_hwspinlock_relax(struct hwspinlock *lock)
  71 {
  72         ndelay(50);
  73 }
  74
  75 static const struct hwspinlock_ops omap_hwspinlock_ops = {
  76         .trylock = omap_hwspinlock_trylock,
  77         .unlock = omap_hwspinlock_unlock,
  78         .relax = omap_hwspinlock_relax,
  79 };
  80
  81 static int 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
 137 reg_fail:
 138         pm_runtime_disable(&pdev->dev);
 139         kfree(bank);
 140 iounmap_base:
 141         iounmap(io_base);
 142         return ret;
 143 }
 144
 145 static int 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
 164 static struct platform_driver omap_hwspinlock_driver = {
 165         .probe          = omap_hwspinlock_probe,
 166         .remove         = omap_hwspinlock_remove,
 167         .driver         = {
 168                 .name   = "omap_hwspinlock",
 169                 .owner  = THIS_MODULE,
 170         },
 171 };
 172
 173 static 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 */
 178 postcore_initcall(omap_hwspinlock_init);
 179
 180 static void __exit omap_hwspinlock_exit(void)
 181 {
 182         platform_driver_unregister(&omap_hwspinlock_driver);
 183 }
 184 module_exit(omap_hwspinlock_exit);
 185
 186 MODULE_LICENSE("GPL v2");
 187 MODULE_DESCRIPTION("Hardware spinlock driver for OMAP");
 188 MODULE_AUTHOR("Simon Que <sque@ti.com>");
 189 MODULE_AUTHOR("Hari Kanigeri <h-kanigeri2@ti.com>");
 190 MODULE_AUTHOR("Ohad Ben-Cohen <ohad@wizery.com>");