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         /*
 102          * make sure the module is enabled and clocked before reading
 103          * the module SYSSTATUS register
 104          */
 105         pm_runtime_enable(&pdev->dev);
 106         ret = pm_runtime_get_sync(&pdev->dev);
 107         if (ret < 0) {
 108                 pm_runtime_put_noidle(&pdev->dev);
 109                 goto iounmap_base;
 110         }
 111
 112         /* Determine number of locks */
 113         i = readl(io_base + SYSSTATUS_OFFSET);
 114         i >>= SPINLOCK_NUMLOCKS_BIT_OFFSET;
 115
 116         /*
 117          * runtime PM will make sure the clock of this module is
 118          * enabled again iff at least one lock is requested
 119          */
 120         ret = pm_runtime_put(&pdev->dev);
 121         if (ret < 0)
 122                 goto iounmap_base;
 123
 124         /* one of the four lsb's must be set, and nothing else */
 125         if (hweight_long(i & 0xf) != 1 || i > 8) {
 126                 ret = -EINVAL;
 127                 goto iounmap_base;
 128         }
 129
 130         num_locks = i * 32; /* actual number of locks in this device */
 131
 132         bank = kzalloc(sizeof(*bank) + num_locks * sizeof(*hwlock), GFP_KERNEL);
 133         if (!bank) {
 134                 ret = -ENOMEM;
 135                 goto iounmap_base;
 136         }
 137
 138         platform_set_drvdata(pdev, bank);
 139
 140         for (i = 0, hwlock = &bank->lock[0]; i < num_locks; i++, hwlock++)
 141                 hwlock->priv = io_base + LOCK_BASE_OFFSET + sizeof(u32) * i;
 142
 143         ret = hwspin_lock_register(bank, &pdev->dev, &omap_hwspinlock_ops,
 144                                                 pdata->base_id, num_locks);
 145         if (ret)
 146                 goto reg_fail;
 147
 148         return 0;
 149
 150 reg_fail:
 151         kfree(bank);
 152 iounmap_base:
 153         pm_runtime_disable(&pdev->dev);
 154         iounmap(io_base);
 155         return ret;
 156 }
 157
 158 static int omap_hwspinlock_remove(struct platform_device *pdev)
 159 {
 160         struct hwspinlock_device *bank = platform_get_drvdata(pdev);
 161         void __iomem *io_base = bank->lock[0].priv - LOCK_BASE_OFFSET;
 162         int ret;
 163
 164         ret = hwspin_lock_unregister(bank);
 165         if (ret) {
 166                 dev_err(&pdev->dev, "%s failed: %d\n", __func__, ret);
 167                 return ret;
 168         }
 169
 170         pm_runtime_disable(&pdev->dev);
 171         iounmap(io_base);
 172         kfree(bank);
 173
 174         return 0;
 175 }
 176
 177 static struct platform_driver omap_hwspinlock_driver = {
 178         .probe          = omap_hwspinlock_probe,
 179         .remove         = omap_hwspinlock_remove,
 180         .driver         = {
 181                 .name   = "omap_hwspinlock",
 182         },
 183 };
 184
 185 static int __init omap_hwspinlock_init(void)
 186 {
 187         return platform_driver_register(&omap_hwspinlock_driver);
 188 }
 189 /* board init code might need to reserve hwspinlocks for predefined purposes */
 190 postcore_initcall(omap_hwspinlock_init);
 191
 192 static void __exit omap_hwspinlock_exit(void)
 193 {
 194         platform_driver_unregister(&omap_hwspinlock_driver);
 195 }
 196 module_exit(omap_hwspinlock_exit);
 197
 198 MODULE_LICENSE("GPL v2");
 199 MODULE_DESCRIPTION("Hardware spinlock driver for OMAP");
 200 MODULE_AUTHOR("Simon Que <sque@ti.com>");
 201 MODULE_AUTHOR("Hari Kanigeri <h-kanigeri2@ti.com>");
 202 MODULE_AUTHOR("Ohad Ben-Cohen <ohad@wizery.com>");