1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * u8500 HWSEM driver 4 * 5 * Copyright (C) 2010-2011 ST-Ericsson 6 * 7 * Implements u8500 semaphore handling for protocol 1, no interrupts. 8 * 9 * Author: Mathieu Poirier <mathieu.poirier@linaro.org> 10 * Heavily borrowed from the work of : 11 * Simon Que <sque@ti.com> 12 * Hari Kanigeri <h-kanigeri2@ti.com> 13 * Ohad Ben-Cohen <ohad@wizery.com> 14 */ 15 16 #include <linux/module.h> 17 #include <linux/delay.h> 18 #include <linux/io.h> 19 #include <linux/slab.h> 20 #include <linux/spinlock.h> 21 #include <linux/hwspinlock.h> 22 #include <linux/platform_device.h> 23 24 #include "hwspinlock_internal.h" 25 26 /* 27 * Implementation of STE's HSem protocol 1 without interrutps. 28 * The only masterID we allow is '0x01' to force people to use 29 * HSems for synchronisation between processors rather than processes 30 * on the ARM core. 31 */ 32 33 #define U8500_MAX_SEMAPHORE 32 /* a total of 32 semaphore */ 34 #define RESET_SEMAPHORE (0) /* free */ 35 36 /* 37 * CPU ID for master running u8500 kernel. 38 * Hswpinlocks should only be used to synchonise operations 39 * between the Cortex A9 core and the other CPUs. Hence 40 * forcing the masterID to a preset value. 41 */ 42 #define HSEM_MASTER_ID 0x01 43 44 #define HSEM_REGISTER_OFFSET 0x08 45 46 #define HSEM_CTRL_REG 0x00 47 #define HSEM_ICRALL 0x90 48 #define HSEM_PROTOCOL_1 0x01 49 50 static int u8500_hsem_trylock(struct hwspinlock *lock) 51 { 52 void __iomem *lock_addr = lock->priv; 53 54 writel(HSEM_MASTER_ID, lock_addr); 55 56 /* get only first 4 bit and compare to masterID. 57 * if equal, we have the semaphore, otherwise 58 * someone else has it. 59 */ 60 return (HSEM_MASTER_ID == (0x0F & readl(lock_addr))); 61 } 62 63 static void u8500_hsem_unlock(struct hwspinlock *lock) 64 { 65 void __iomem *lock_addr = lock->priv; 66 67 /* release the lock by writing 0 to it */ 68 writel(RESET_SEMAPHORE, lock_addr); 69 } 70 71 /* 72 * u8500: what value is recommended here ? 73 */ 74 static void u8500_hsem_relax(struct hwspinlock *lock) 75 { 76 ndelay(50); 77 } 78 79 static const struct hwspinlock_ops u8500_hwspinlock_ops = { 80 .trylock = u8500_hsem_trylock, 81 .unlock = u8500_hsem_unlock, 82 .relax = u8500_hsem_relax, 83 }; 84 85 static int u8500_hsem_probe(struct platform_device *pdev) 86 { 87 struct hwspinlock_pdata *pdata = pdev->dev.platform_data; 88 struct hwspinlock_device *bank; 89 struct hwspinlock *hwlock; 90 void __iomem *io_base; 91 int i, num_locks = U8500_MAX_SEMAPHORE; 92 ulong val; 93 94 if (!pdata) 95 return -ENODEV; 96 97 io_base = devm_platform_ioremap_resource(pdev, 0); 98 if (IS_ERR(io_base)) 99 return PTR_ERR(io_base); 100 101 /* make sure protocol 1 is selected */ 102 val = readl(io_base + HSEM_CTRL_REG); 103 writel((val & ~HSEM_PROTOCOL_1), io_base + HSEM_CTRL_REG); 104 105 /* clear all interrupts */ 106 writel(0xFFFF, io_base + HSEM_ICRALL); 107 108 bank = devm_kzalloc(&pdev->dev, struct_size(bank, lock, num_locks), 109 GFP_KERNEL); 110 if (!bank) 111 return -ENOMEM; 112 113 platform_set_drvdata(pdev, bank); 114 115 for (i = 0, hwlock = &bank->lock[0]; i < num_locks; i++, hwlock++) 116 hwlock->priv = io_base + HSEM_REGISTER_OFFSET + sizeof(u32) * i; 117 118 return devm_hwspin_lock_register(&pdev->dev, bank, 119 &u8500_hwspinlock_ops, 120 pdata->base_id, num_locks); 121 } 122 123 static int u8500_hsem_remove(struct platform_device *pdev) 124 { 125 struct hwspinlock_device *bank = platform_get_drvdata(pdev); 126 void __iomem *io_base = bank->lock[0].priv - HSEM_REGISTER_OFFSET; 127 128 /* clear all interrupts */ 129 writel(0xFFFF, io_base + HSEM_ICRALL); 130 131 return 0; 132 } 133 134 static struct platform_driver u8500_hsem_driver = { 135 .probe = u8500_hsem_probe, 136 .remove = u8500_hsem_remove, 137 .driver = { 138 .name = "u8500_hsem", 139 }, 140 }; 141 142 static int __init u8500_hsem_init(void) 143 { 144 return platform_driver_register(&u8500_hsem_driver); 145 } 146 /* board init code might need to reserve hwspinlocks for predefined purposes */ 147 postcore_initcall(u8500_hsem_init); 148 149 static void __exit u8500_hsem_exit(void) 150 { 151 platform_driver_unregister(&u8500_hsem_driver); 152 } 153 module_exit(u8500_hsem_exit); 154 155 MODULE_LICENSE("GPL v2"); 156 MODULE_DESCRIPTION("Hardware Spinlock driver for u8500"); 157 MODULE_AUTHOR("Mathieu Poirier <mathieu.poirier@linaro.org>"); 158