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* OMAP hardware spinlock driver
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* Copyright (C) 2010 Texas Instruments Incorporated - http://www.ti.com
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* Contact: 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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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* version 2 as published by the Free Software Foundation.
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* This program is distributed in the hope that it will be useful, but
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* WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* General Public License for more details.
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#include <linux/kernel.h>
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#include <linux/module.h>
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#include <linux/device.h>
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#include <linux/delay.h>
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#include <linux/bitops.h>
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#include <linux/pm_runtime.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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/* Spinlock register offsets */
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#define SYSSTATUS_OFFSET 0x0014
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#define LOCK_BASE_OFFSET 0x0800
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#define SPINLOCK_NUMLOCKS_BIT_OFFSET (24)
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/* Possible values of SPINLOCK_LOCK_REG */
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#define SPINLOCK_NOTTAKEN (0) /* free */
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#define SPINLOCK_TAKEN (1) /* locked */
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#define to_omap_hwspinlock(lock) \
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container_of(lock, struct omap_hwspinlock, lock)
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struct omap_hwspinlock {
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struct hwspinlock lock;
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struct omap_hwspinlock_state {
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int num_locks; /* Total number of locks in system */
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void __iomem *io_base; /* Mapped base address */
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static int omap_hwspinlock_trylock(struct hwspinlock *lock)
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struct omap_hwspinlock *omap_lock = to_omap_hwspinlock(lock);
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/* attempt to acquire the lock by reading its value */
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return (SPINLOCK_NOTTAKEN == readl(omap_lock->addr));
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static void omap_hwspinlock_unlock(struct hwspinlock *lock)
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struct omap_hwspinlock *omap_lock = to_omap_hwspinlock(lock);
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/* release the lock by writing 0 to it */
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writel(SPINLOCK_NOTTAKEN, omap_lock->addr);
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* relax the OMAP interconnect while spinning on it.
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* The specs recommended that the retry delay time will be
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* just over half of the time that a requester would be
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* expected to hold the lock.
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* The number below is taken from an hardware specs example,
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* obviously it is somewhat arbitrary.
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static void omap_hwspinlock_relax(struct hwspinlock *lock)
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static const struct hwspinlock_ops omap_hwspinlock_ops = {
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.trylock = omap_hwspinlock_trylock,
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.unlock = omap_hwspinlock_unlock,
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.relax = omap_hwspinlock_relax,
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static int __devinit omap_hwspinlock_probe(struct platform_device *pdev)
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struct omap_hwspinlock *omap_lock;
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struct omap_hwspinlock_state *state;
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struct hwspinlock *lock;
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void __iomem *io_base;
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res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
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state = kzalloc(sizeof(*state), GFP_KERNEL);
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io_base = ioremap(res->start, resource_size(res));
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/* Determine number of locks */
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i = readl(io_base + SYSSTATUS_OFFSET);
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i >>= SPINLOCK_NUMLOCKS_BIT_OFFSET;
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/* one of the four lsb's must be set, and nothing else */
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if (hweight_long(i & 0xf) != 1 || i > 8) {
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state->num_locks = i * 32;
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state->io_base = io_base;
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platform_set_drvdata(pdev, state);
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* runtime PM will make sure the clock of this module is
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* enabled iff at least one lock is requested
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pm_runtime_enable(&pdev->dev);
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for (i = 0; i < state->num_locks; i++) {
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omap_lock = kzalloc(sizeof(*omap_lock), GFP_KERNEL);
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omap_lock->lock.dev = &pdev->dev;
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omap_lock->lock.owner = THIS_MODULE;
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omap_lock->lock.id = i;
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omap_lock->lock.ops = &omap_hwspinlock_ops;
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omap_lock->addr = io_base + LOCK_BASE_OFFSET + sizeof(u32) * i;
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ret = hwspin_lock_register(&omap_lock->lock);
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lock = hwspin_lock_unregister(i);
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/* this should't happen, but let's give our best effort */
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dev_err(&pdev->dev, "%s: cleanups failed\n", __func__);
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omap_lock = to_omap_hwspinlock(lock);
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pm_runtime_disable(&pdev->dev);
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static int omap_hwspinlock_remove(struct platform_device *pdev)
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struct omap_hwspinlock_state *state = platform_get_drvdata(pdev);
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struct hwspinlock *lock;
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struct omap_hwspinlock *omap_lock;
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for (i = 0; i < state->num_locks; i++) {
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lock = hwspin_lock_unregister(i);
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/* this shouldn't happen at this point. if it does, at least
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* don't continue with the remove */
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dev_err(&pdev->dev, "%s: failed on %d\n", __func__, i);
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omap_lock = to_omap_hwspinlock(lock);
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pm_runtime_disable(&pdev->dev);
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iounmap(state->io_base);
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static struct platform_driver omap_hwspinlock_driver = {
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.probe = omap_hwspinlock_probe,
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.remove = omap_hwspinlock_remove,
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.name = "omap_hwspinlock",
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static int __init omap_hwspinlock_init(void)
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return platform_driver_register(&omap_hwspinlock_driver);
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/* board init code might need to reserve hwspinlocks for predefined purposes */
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postcore_initcall(omap_hwspinlock_init);
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static void __exit omap_hwspinlock_exit(void)
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platform_driver_unregister(&omap_hwspinlock_driver);
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module_exit(omap_hwspinlock_exit);
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MODULE_LICENSE("GPL v2");
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MODULE_DESCRIPTION("Hardware spinlock driver for OMAP");
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MODULE_AUTHOR("Simon Que <sque@ti.com>");
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MODULE_AUTHOR("Hari Kanigeri <h-kanigeri2@ti.com>");
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MODULE_AUTHOR("Ohad Ben-Cohen <ohad@wizery.com>");
added
removed
drivers/hwspinlock/omap_hwspinlock.c
