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>");