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         struct omap_hwspinlock lock[0]; /* Array of 'num_locks' locks */
  56 };
  57
  58 static int omap_hwspinlock_trylock(struct hwspinlock *lock)
  59 {
  60         struct omap_hwspinlock *omap_lock = to_omap_hwspinlock(lock);
  61
  62         /* attempt to acquire the lock by reading its value */
  63         return (SPINLOCK_NOTTAKEN == readl(omap_lock->addr));
  64 }
  65
  66 static void omap_hwspinlock_unlock(struct hwspinlock *lock)
  67 {
  68         struct omap_hwspinlock *omap_lock = to_omap_hwspinlock(lock);
  69
  70         /* release the lock by writing 0 to it */
  71         writel(SPINLOCK_NOTTAKEN, omap_lock->addr);
  72 }
  73
  74 /*
  75  * relax the OMAP interconnect while spinning on it.
  76  *
  77  * The specs recommended that the retry delay time will be
  78  * just over half of the time that a requester would be
  79  * expected to hold the lock.
  80  *
  81  * The number below is taken from an hardware specs example,
  82  * obviously it is somewhat arbitrary.
  83  */
  84 static void omap_hwspinlock_relax(struct hwspinlock *lock)
  85 {
  86         ndelay(50);
  87 }
  88
  89 static const struct hwspinlock_ops omap_hwspinlock_ops = {
  90         .trylock = omap_hwspinlock_trylock,
  91         .unlock = omap_hwspinlock_unlock,
  92         .relax = omap_hwspinlock_relax,
  93 };
  94
  95 static int __devinit omap_hwspinlock_probe(struct platform_device *pdev)
  96 {
  97         struct omap_hwspinlock *omap_lock;
  98         struct omap_hwspinlock_state *state;
  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         io_base = ioremap(res->start, resource_size(res));
 108         if (!io_base)
 109                 return -ENOMEM;
 110
 111         /* Determine number of locks */
 112         i = readl(io_base + SYSSTATUS_OFFSET);
 113         i >>= SPINLOCK_NUMLOCKS_BIT_OFFSET;
 114
 115         /* one of the four lsb's must be set, and nothing else */
 116         if (hweight_long(i & 0xf) != 1 || i > 8) {
 117                 ret = -EINVAL;
 118                 goto iounmap_base;
 119         }
 120
 121         i *= 32; /* actual number of locks in this device */
 122
 123         state = kzalloc(sizeof(*state) + i * sizeof(*omap_lock), GFP_KERNEL);
 124         if (!state) {
 125                 ret = -ENOMEM;
 126                 goto iounmap_base;
 127         }
 128
 129         state->num_locks = i;
 130         state->io_base = io_base;
 131
 132         platform_set_drvdata(pdev, state);
 133
 134         /*
 135          * runtime PM will make sure the clock of this module is
 136          * enabled iff at least one lock is requested
 137          */
 138         pm_runtime_enable(&pdev->dev);
 139
 140         for (i = 0; i < state->num_locks; i++) {
 141                 omap_lock = &state->lock[i];
 142
 143                 omap_lock->lock.dev = &pdev->dev;
 144                 omap_lock->lock.id = i;
 145                 omap_lock->lock.ops = &omap_hwspinlock_ops;
 146                 omap_lock->addr = io_base + LOCK_BASE_OFFSET + sizeof(u32) * i;
 147
 148                 ret = hwspin_lock_register(&omap_lock->lock);
 149                 if (ret)
 150                         goto free_locks;
 151         }
 152
 153         return 0;
 154
 155 free_locks:
 156         while (--i >= 0)
 157                 hwspin_lock_unregister(i);
 158         pm_runtime_disable(&pdev->dev);
 159         kfree(state);
 160 iounmap_base:
 161         iounmap(io_base);
 162         return ret;
 163 }
 164
 165 static int omap_hwspinlock_remove(struct platform_device *pdev)
 166 {
 167         struct omap_hwspinlock_state *state = platform_get_drvdata(pdev);
 168         struct hwspinlock *lock;
 169         int i;
 170
 171         for (i = 0; i < state->num_locks; i++) {
 172                 lock = hwspin_lock_unregister(i);
 173                 /* this shouldn't happen at this point. if it does, at least
 174                  * don't continue with the remove */
 175                 if (!lock) {
 176                         dev_err(&pdev->dev, "%s: failed on %d\n", __func__, i);
 177                         return -EBUSY;
 178                 }
 179         }
 180
 181         pm_runtime_disable(&pdev->dev);
 182         iounmap(state->io_base);
 183         kfree(state);
 184
 185         return 0;
 186 }
 187
 188 static struct platform_driver omap_hwspinlock_driver = {
 189         .probe          = omap_hwspinlock_probe,
 190         .remove         = omap_hwspinlock_remove,
 191         .driver         = {
 192                 .name   = "omap_hwspinlock",
 193                 .owner  = THIS_MODULE,
 194         },
 195 };
 196
 197 static int __init omap_hwspinlock_init(void)
 198 {
 199         return platform_driver_register(&omap_hwspinlock_driver);
 200 }
 201 /* board init code might need to reserve hwspinlocks for predefined purposes */
 202 postcore_initcall(omap_hwspinlock_init);
 203
 204 static void __exit omap_hwspinlock_exit(void)
 205 {
 206         platform_driver_unregister(&omap_hwspinlock_driver);
 207 }
 208 module_exit(omap_hwspinlock_exit);
 209
 210 MODULE_LICENSE("GPL v2");
 211 MODULE_DESCRIPTION("Hardware spinlock driver for OMAP");
 212 MODULE_AUTHOR("Simon Que <sque@ti.com>");
 213 MODULE_AUTHOR("Hari Kanigeri <h-kanigeri2@ti.com>");
 214 MODULE_AUTHOR("Ohad Ben-Cohen <ohad@wizery.com>");