1 /* 2 * u8500 HWSEM driver 3 * 4 * Copyright (C) 2010-2011 ST-Ericsson 5 * 6 * Implements u8500 semaphore handling for protocol 1, no interrupts. 7 * 8 * Author: Mathieu Poirier <mathieu.poirier@linaro.org> 9 * Heavily borrowed from the work of : 10 * Simon Que <sque@ti.com> 11 * Hari Kanigeri <h-kanigeri2@ti.com> 12 * Ohad Ben-Cohen <ohad@wizery.com> 13 * 14 * This program is free software; you can redistribute it and/or 15 * modify it under the terms of the GNU General Public License 16 * version 2 as published by the Free Software Foundation. 17 * 18 * This program is distributed in the hope that it will be useful, but 19 * WITHOUT ANY WARRANTY; without even the implied warranty of 20 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 21 * General Public License for more details. 22 */ 23 24 #include <linux/module.h> 25 #include <linux/delay.h> 26 #include <linux/io.h> 27 #include <linux/pm_runtime.h> 28 #include <linux/slab.h> 29 #include <linux/spinlock.h> 30 #include <linux/hwspinlock.h> 31 #include <linux/platform_device.h> 32 33 #include "hwspinlock_internal.h" 34 35 /* 36 * Implementation of STE's HSem protocol 1 without interrutps. 37 * The only masterID we allow is '0x01' to force people to use 38 * HSems for synchronisation between processors rather than processes 39 * on the ARM core. 40 */ 41 42 #define U8500_MAX_SEMAPHORE 32 /* a total of 32 semaphore */ 43 #define RESET_SEMAPHORE (0) /* free */ 44 45 /* 46 * CPU ID for master running u8500 kernel. 47 * Hswpinlocks should only be used to synchonise operations 48 * between the Cortex A9 core and the other CPUs. Hence 49 * forcing the masterID to a preset value. 50 */ 51 #define HSEM_MASTER_ID 0x01 52 53 #define HSEM_REGISTER_OFFSET 0x08 54 55 #define HSEM_CTRL_REG 0x00 56 #define HSEM_ICRALL 0x90 57 #define HSEM_PROTOCOL_1 0x01 58 59 static int u8500_hsem_trylock(struct hwspinlock *lock) 60 { 61 void __iomem *lock_addr = lock->priv; 62 63 writel(HSEM_MASTER_ID, lock_addr); 64 65 /* get only first 4 bit and compare to masterID. 66 * if equal, we have the semaphore, otherwise 67 * someone else has it. 68 */ 69 return (HSEM_MASTER_ID == (0x0F & readl(lock_addr))); 70 } 71 72 static void u8500_hsem_unlock(struct hwspinlock *lock) 73 { 74 void __iomem *lock_addr = lock->priv; 75 76 /* release the lock by writing 0 to it */ 77 writel(RESET_SEMAPHORE, lock_addr); 78 } 79 80 /* 81 * u8500: what value is recommended here ? 82 */ 83 static void u8500_hsem_relax(struct hwspinlock *lock) 84 { 85 ndelay(50); 86 } 87 88 static const struct hwspinlock_ops u8500_hwspinlock_ops = { 89 .trylock = u8500_hsem_trylock, 90 .unlock = u8500_hsem_unlock, 91 .relax = u8500_hsem_relax, 92 }; 93 94 static int u8500_hsem_probe(struct platform_device *pdev) 95 { 96 struct hwspinlock_pdata *pdata = pdev->dev.platform_data; 97 struct hwspinlock_device *bank; 98 struct hwspinlock *hwlock; 99 struct resource *res; 100 void __iomem *io_base; 101 int i, ret, num_locks = U8500_MAX_SEMAPHORE; 102 ulong val; 103 104 if (!pdata) 105 return -ENODEV; 106 107 res = platform_get_resource(pdev, IORESOURCE_MEM, 0); 108 if (!res) 109 return -ENODEV; 110 111 io_base = ioremap(res->start, resource_size(res)); 112 if (!io_base) 113 return -ENOMEM; 114 115 /* make sure protocol 1 is selected */ 116 val = readl(io_base + HSEM_CTRL_REG); 117 writel((val & ~HSEM_PROTOCOL_1), io_base + HSEM_CTRL_REG); 118 119 /* clear all interrupts */ 120 writel(0xFFFF, io_base + HSEM_ICRALL); 121 122 bank = kzalloc(sizeof(*bank) + num_locks * sizeof(*hwlock), GFP_KERNEL); 123 if (!bank) { 124 ret = -ENOMEM; 125 goto iounmap_base; 126 } 127 128 platform_set_drvdata(pdev, bank); 129 130 for (i = 0, hwlock = &bank->lock[0]; i < num_locks; i++, hwlock++) 131 hwlock->priv = io_base + HSEM_REGISTER_OFFSET + sizeof(u32) * i; 132 133 /* no pm needed for HSem but required to comply with hwspilock core */ 134 pm_runtime_enable(&pdev->dev); 135 136 ret = hwspin_lock_register(bank, &pdev->dev, &u8500_hwspinlock_ops, 137 pdata->base_id, num_locks); 138 if (ret) 139 goto reg_fail; 140 141 return 0; 142 143 reg_fail: 144 pm_runtime_disable(&pdev->dev); 145 kfree(bank); 146 iounmap_base: 147 iounmap(io_base); 148 return ret; 149 } 150 151 static int u8500_hsem_remove(struct platform_device *pdev) 152 { 153 struct hwspinlock_device *bank = platform_get_drvdata(pdev); 154 void __iomem *io_base = bank->lock[0].priv - HSEM_REGISTER_OFFSET; 155 int ret; 156 157 /* clear all interrupts */ 158 writel(0xFFFF, io_base + HSEM_ICRALL); 159 160 ret = hwspin_lock_unregister(bank); 161 if (ret) { 162 dev_err(&pdev->dev, "%s failed: %d\n", __func__, ret); 163 return ret; 164 } 165 166 pm_runtime_disable(&pdev->dev); 167 iounmap(io_base); 168 kfree(bank); 169 170 return 0; 171 } 172 173 static struct platform_driver u8500_hsem_driver = { 174 .probe = u8500_hsem_probe, 175 .remove = u8500_hsem_remove, 176 .driver = { 177 .name = "u8500_hsem", 178 }, 179 }; 180 181 static int __init u8500_hsem_init(void) 182 { 183 return platform_driver_register(&u8500_hsem_driver); 184 } 185 /* board init code might need to reserve hwspinlocks for predefined purposes */ 186 postcore_initcall(u8500_hsem_init); 187 188 static void __exit u8500_hsem_exit(void) 189 { 190 platform_driver_unregister(&u8500_hsem_driver); 191 } 192 module_exit(u8500_hsem_exit); 193 194 MODULE_LICENSE("GPL v2"); 195 MODULE_DESCRIPTION("Hardware Spinlock driver for u8500"); 196 MODULE_AUTHOR("Mathieu Poirier <mathieu.poirier@linaro.org>"); 197