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1// SPDX-License-Identifier: GPL-2.02/*3 * u8500 HWSEM driver4 *5 * Copyright (C) 2010-2011 ST-Ericsson6 *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 use29 * HSems for synchronisation between processors rather than processes30 * 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 operations39 * between the Cortex A9 core and the other CPUs. Hence40 * forcing the masterID to a preset value.41 */42#define HSEM_MASTER_ID 0x0143 44#define HSEM_REGISTER_OFFSET 0x0845 46#define HSEM_CTRL_REG 0x0047#define HSEM_ICRALL 0x9048#define HSEM_PROTOCOL_1 0x0149 50static 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, otherwise58 * someone else has it.59 */60 return (HSEM_MASTER_ID == (0x0F & readl(lock_addr)));61}62 63static 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 */74static void u8500_hsem_relax(struct hwspinlock *lock)75{76 ndelay(50);77}78 79static const struct hwspinlock_ops u8500_hwspinlock_ops = {80 .trylock = u8500_hsem_trylock,81 .unlock = u8500_hsem_unlock,82 .relax = u8500_hsem_relax,83};84 85static 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 123static void 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 132static struct platform_driver u8500_hsem_driver = {133 .probe = u8500_hsem_probe,134 .remove_new = u8500_hsem_remove,135 .driver = {136 .name = "u8500_hsem",137 },138};139 140static int __init u8500_hsem_init(void)141{142 return platform_driver_register(&u8500_hsem_driver);143}144/* board init code might need to reserve hwspinlocks for predefined purposes */145postcore_initcall(u8500_hsem_init);146 147static void __exit u8500_hsem_exit(void)148{149 platform_driver_unregister(&u8500_hsem_driver);150}151module_exit(u8500_hsem_exit);152 153MODULE_LICENSE("GPL v2");154MODULE_DESCRIPTION("Hardware Spinlock driver for u8500");155MODULE_AUTHOR("Mathieu Poirier <mathieu.poirier@linaro.org>");156