158 lines
3.9 KiB
C
158 lines
3.9 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* u8500 HWSEM driver
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*
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* Copyright (C) 2010-2011 ST-Ericsson
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*
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* Implements u8500 semaphore handling for protocol 1, no interrupts.
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*
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* Author: Mathieu Poirier <mathieu.poirier@linaro.org>
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* Heavily borrowed from the work of :
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* Simon Que <sque@ti.com>
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* Hari Kanigeri <h-kanigeri2@ti.com>
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* Ohad Ben-Cohen <ohad@wizery.com>
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*/
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#include <linux/module.h>
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#include <linux/delay.h>
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#include <linux/io.h>
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#include <linux/slab.h>
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#include <linux/spinlock.h>
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#include <linux/hwspinlock.h>
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#include <linux/platform_device.h>
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#include "hwspinlock_internal.h"
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/*
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* Implementation of STE's HSem protocol 1 without interrutps.
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* The only masterID we allow is '0x01' to force people to use
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* HSems for synchronisation between processors rather than processes
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* on the ARM core.
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*/
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#define U8500_MAX_SEMAPHORE 32 /* a total of 32 semaphore */
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#define RESET_SEMAPHORE (0) /* free */
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/*
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* CPU ID for master running u8500 kernel.
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* Hswpinlocks should only be used to synchonise operations
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* between the Cortex A9 core and the other CPUs. Hence
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* forcing the masterID to a preset value.
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*/
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#define HSEM_MASTER_ID 0x01
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#define HSEM_REGISTER_OFFSET 0x08
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#define HSEM_CTRL_REG 0x00
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#define HSEM_ICRALL 0x90
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#define HSEM_PROTOCOL_1 0x01
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static int u8500_hsem_trylock(struct hwspinlock *lock)
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{
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void __iomem *lock_addr = lock->priv;
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writel(HSEM_MASTER_ID, lock_addr);
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/* get only first 4 bit and compare to masterID.
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* if equal, we have the semaphore, otherwise
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* someone else has it.
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*/
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return (HSEM_MASTER_ID == (0x0F & readl(lock_addr)));
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}
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static void u8500_hsem_unlock(struct hwspinlock *lock)
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{
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void __iomem *lock_addr = lock->priv;
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/* release the lock by writing 0 to it */
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writel(RESET_SEMAPHORE, lock_addr);
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}
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/*
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* u8500: what value is recommended here ?
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*/
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static void u8500_hsem_relax(struct hwspinlock *lock)
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{
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ndelay(50);
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}
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static const struct hwspinlock_ops u8500_hwspinlock_ops = {
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.trylock = u8500_hsem_trylock,
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.unlock = u8500_hsem_unlock,
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.relax = u8500_hsem_relax,
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};
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static int u8500_hsem_probe(struct platform_device *pdev)
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{
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struct hwspinlock_pdata *pdata = pdev->dev.platform_data;
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struct hwspinlock_device *bank;
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struct hwspinlock *hwlock;
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void __iomem *io_base;
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int i, num_locks = U8500_MAX_SEMAPHORE;
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ulong val;
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if (!pdata)
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return -ENODEV;
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io_base = devm_platform_ioremap_resource(pdev, 0);
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if (IS_ERR(io_base))
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return PTR_ERR(io_base);
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/* make sure protocol 1 is selected */
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val = readl(io_base + HSEM_CTRL_REG);
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writel((val & ~HSEM_PROTOCOL_1), io_base + HSEM_CTRL_REG);
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/* clear all interrupts */
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writel(0xFFFF, io_base + HSEM_ICRALL);
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bank = devm_kzalloc(&pdev->dev, struct_size(bank, lock, num_locks),
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GFP_KERNEL);
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if (!bank)
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return -ENOMEM;
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platform_set_drvdata(pdev, bank);
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for (i = 0, hwlock = &bank->lock[0]; i < num_locks; i++, hwlock++)
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hwlock->priv = io_base + HSEM_REGISTER_OFFSET + sizeof(u32) * i;
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return devm_hwspin_lock_register(&pdev->dev, bank,
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&u8500_hwspinlock_ops,
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pdata->base_id, num_locks);
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}
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static int u8500_hsem_remove(struct platform_device *pdev)
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{
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struct hwspinlock_device *bank = platform_get_drvdata(pdev);
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void __iomem *io_base = bank->lock[0].priv - HSEM_REGISTER_OFFSET;
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/* clear all interrupts */
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writel(0xFFFF, io_base + HSEM_ICRALL);
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return 0;
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}
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static struct platform_driver u8500_hsem_driver = {
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.probe = u8500_hsem_probe,
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.remove = u8500_hsem_remove,
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.driver = {
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.name = "u8500_hsem",
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},
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};
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static int __init u8500_hsem_init(void)
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{
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return platform_driver_register(&u8500_hsem_driver);
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}
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/* board init code might need to reserve hwspinlocks for predefined purposes */
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postcore_initcall(u8500_hsem_init);
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static void __exit u8500_hsem_exit(void)
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{
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platform_driver_unregister(&u8500_hsem_driver);
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}
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module_exit(u8500_hsem_exit);
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MODULE_LICENSE("GPL v2");
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MODULE_DESCRIPTION("Hardware Spinlock driver for u8500");
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MODULE_AUTHOR("Mathieu Poirier <mathieu.poirier@linaro.org>");
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