drivers/hwspinlock/omap_hwspinlock.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * OMAP hardware spinlock driver
   4  *
   5  * Copyright (C) 2010-2015 Texas Instruments Incorporated - http://www.ti.com
   6  *
   7  * Contact: Simon Que <sque@ti.com>
   8  *          Hari Kanigeri <h-kanigeri2@ti.com>
   9  *          Ohad Ben-Cohen <ohad@wizery.com>
  10  */
  11
  12 #include <linux/kernel.h>
  13 #include <linux/module.h>
  14 #include <linux/device.h>
  15 #include <linux/delay.h>
  16 #include <linux/io.h>
  17 #include <linux/bitops.h>
  18 #include <linux/pm_runtime.h>
  19 #include <linux/slab.h>
  20 #include <linux/spinlock.h>
  21 #include <linux/hwspinlock.h>
  22 #include <linux/of.h>
  23 #include <linux/platform_device.h>
  24
  25 #include "hwspinlock_internal.h"
  26
  27 /* Spinlock register offsets */
  28 #define SYSSTATUS_OFFSET                0x0014
  29 #define LOCK_BASE_OFFSET                0x0800
  30
  31 #define SPINLOCK_NUMLOCKS_BIT_OFFSET    (24)
  32
  33 /* Possible values of SPINLOCK_LOCK_REG */
  34 #define SPINLOCK_NOTTAKEN               (0)     /* free */
  35 #define SPINLOCK_TAKEN                  (1)     /* locked */
  36
  37 static int omap_hwspinlock_trylock(struct hwspinlock *lock)
  38 {
  39         void __iomem *lock_addr = lock->priv;
  40
  41         /* attempt to acquire the lock by reading its value */
  42         return (SPINLOCK_NOTTAKEN == readl(lock_addr));
  43 }
  44
  45 static void omap_hwspinlock_unlock(struct hwspinlock *lock)
  46 {
  47         void __iomem *lock_addr = lock->priv;
  48
  49         /* release the lock by writing 0 to it */
  50         writel(SPINLOCK_NOTTAKEN, lock_addr);
  51 }
  52
  53 /*
  54  * relax the OMAP interconnect while spinning on it.
  55  *
  56  * The specs recommended that the retry delay time will be
  57  * just over half of the time that a requester would be
  58  * expected to hold the lock.
  59  *
  60  * The number below is taken from an hardware specs example,
  61  * obviously it is somewhat arbitrary.
  62  */
  63 static void omap_hwspinlock_relax(struct hwspinlock *lock)
  64 {
  65         ndelay(50);
  66 }
  67
  68 static const struct hwspinlock_ops omap_hwspinlock_ops = {
  69         .trylock = omap_hwspinlock_trylock,
  70         .unlock = omap_hwspinlock_unlock,
  71         .relax = omap_hwspinlock_relax,
  72 };
  73
  74 static int omap_hwspinlock_probe(struct platform_device *pdev)
  75 {
  76         struct device_node *node = pdev->dev.of_node;
  77         struct hwspinlock_device *bank;
  78         struct hwspinlock *hwlock;
  79         void __iomem *io_base;
  80         int num_locks, i, ret;
  81         /* Only a single hwspinlock block device is supported */
  82         int base_id = 0;
  83
  84         if (!node)
  85                 return -ENODEV;
  86
  87         io_base = devm_platform_ioremap_resource(pdev, 0);
  88         if (IS_ERR(io_base))
  89                 return PTR_ERR(io_base);
  90
  91         /*
  92          * make sure the module is enabled and clocked before reading
  93          * the module SYSSTATUS register
  94          */
  95         pm_runtime_enable(&pdev->dev);
  96         ret = pm_runtime_get_sync(&pdev->dev);
  97         if (ret < 0) {
  98                 pm_runtime_put_noidle(&pdev->dev);
  99                 goto runtime_err;
 100         }
 101
 102         /* Determine number of locks */
 103         i = readl(io_base + SYSSTATUS_OFFSET);
 104         i >>= SPINLOCK_NUMLOCKS_BIT_OFFSET;
 105
 106         /*
 107          * runtime PM will make sure the clock of this module is
 108          * enabled again iff at least one lock is requested
 109          */
 110         ret = pm_runtime_put(&pdev->dev);
 111         if (ret < 0)
 112                 goto runtime_err;
 113
 114         /* one of the four lsb's must be set, and nothing else */
 115         if (hweight_long(i & 0xf) != 1 || i > 8) {
 116                 ret = -EINVAL;
 117                 goto runtime_err;
 118         }
 119
 120         num_locks = i * 32; /* actual number of locks in this device */
 121
 122         bank = devm_kzalloc(&pdev->dev, struct_size(bank, lock, num_locks),
 123                             GFP_KERNEL);
 124         if (!bank) {
 125                 ret = -ENOMEM;
 126                 goto runtime_err;
 127         }
 128
 129         platform_set_drvdata(pdev, bank);
 130
 131         for (i = 0, hwlock = &bank->lock[0]; i < num_locks; i++, hwlock++)
 132                 hwlock->priv = io_base + LOCK_BASE_OFFSET + sizeof(u32) * i;
 133
 134         ret = hwspin_lock_register(bank, &pdev->dev, &omap_hwspinlock_ops,
 135                                                 base_id, num_locks);
 136         if (ret)
 137                 goto runtime_err;
 138
 139         dev_dbg(&pdev->dev, "Registered %d locks with HwSpinlock core\n",
 140                 num_locks);
 141
 142         return 0;
 143
 144 runtime_err:
 145         pm_runtime_disable(&pdev->dev);
 146         return ret;
 147 }
 148
 149 static int omap_hwspinlock_remove(struct platform_device *pdev)
 150 {
 151         struct hwspinlock_device *bank = platform_get_drvdata(pdev);
 152         int ret;
 153
 154         ret = hwspin_lock_unregister(bank);
 155         if (ret) {
 156                 dev_err(&pdev->dev, "%s failed: %d\n", __func__, ret);
 157                 return ret;
 158         }
 159
 160         pm_runtime_disable(&pdev->dev);
 161
 162         return 0;
 163 }
 164
 165 static const struct of_device_id omap_hwspinlock_of_match[] = {
 166         { .compatible = "ti,omap4-hwspinlock", },
 167         { .compatible = "ti,am654-hwspinlock", },
 168         { /* end */ },
 169 };
 170 MODULE_DEVICE_TABLE(of, omap_hwspinlock_of_match);
 171
 172 static struct platform_driver omap_hwspinlock_driver = {
 173         .probe          = omap_hwspinlock_probe,
 174         .remove         = omap_hwspinlock_remove,
 175         .driver         = {
 176                 .name   = "omap_hwspinlock",
 177                 .of_match_table = of_match_ptr(omap_hwspinlock_of_match),
 178         },
 179 };
 180
 181 static int __init omap_hwspinlock_init(void)
 182 {
 183         return platform_driver_register(&omap_hwspinlock_driver);
 184 }
 185 /* board init code might need to reserve hwspinlocks for predefined purposes */
 186 postcore_initcall(omap_hwspinlock_init);
 187
 188 static void __exit omap_hwspinlock_exit(void)
 189 {
 190         platform_driver_unregister(&omap_hwspinlock_driver);
 191 }
 192 module_exit(omap_hwspinlock_exit);
 193
 194 MODULE_LICENSE("GPL v2");
 195 MODULE_DESCRIPTION("Hardware spinlock driver for OMAP");
 196 MODULE_AUTHOR("Simon Que <sque@ti.com>");
 197 MODULE_AUTHOR("Hari Kanigeri <h-kanigeri2@ti.com>");
 198 MODULE_AUTHOR("Ohad Ben-Cohen <ohad@wizery.com>");