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 .owner = THIS_MODULE, 183 }, 184 }; 185 186 static int __init omap_hwspinlock_init(void) 187 { 188 return platform_driver_register(&omap_hwspinlock_driver); 189 } 190 /* board init code might need to reserve hwspinlocks for predefined purposes */ 191 postcore_initcall(omap_hwspinlock_init); 192 193 static void __exit omap_hwspinlock_exit(void) 194 { 195 platform_driver_unregister(&omap_hwspinlock_driver); 196 } 197 module_exit(omap_hwspinlock_exit); 198 199 MODULE_LICENSE("GPL v2"); 200 MODULE_DESCRIPTION("Hardware spinlock driver for OMAP"); 201 MODULE_AUTHOR("Simon Que <sque@ti.com>"); 202 MODULE_AUTHOR("Hari Kanigeri <h-kanigeri2@ti.com>"); 203 MODULE_AUTHOR("Ohad Ben-Cohen <ohad@wizery.com>"); 204