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cebaa386d5
For loops with multiple initializers and increments are hard to read and reason about, simplify this by using the looping index to index into the hwspinlock array. Signed-off-by: Andrew Davis <afd@ti.com> Link: https://lore.kernel.org/r/20240208165114.63148-4-afd@ti.com Signed-off-by: Bjorn Andersson <andersson@kernel.org>
159 lines
4.2 KiB
C
159 lines
4.2 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* OMAP hardware spinlock driver
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*
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* Copyright (C) 2010-2021 Texas Instruments Incorporated - https://www.ti.com
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*
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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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* Suman Anna <s-anna@ti.com>
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*/
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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/io.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/of.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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static int omap_hwspinlock_trylock(struct hwspinlock *lock)
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{
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void __iomem *lock_addr = lock->priv;
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/* attempt to acquire the lock by reading its value */
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return (SPINLOCK_NOTTAKEN == readl(lock_addr));
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}
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static void omap_hwspinlock_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(SPINLOCK_NOTTAKEN, lock_addr);
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}
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/*
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* relax the OMAP interconnect while spinning on it.
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*
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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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*
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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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*/
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static void omap_hwspinlock_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 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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};
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static int omap_hwspinlock_probe(struct platform_device *pdev)
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{
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struct hwspinlock_device *bank;
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void __iomem *io_base;
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int num_locks, i, ret;
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/* Only a single hwspinlock block device is supported */
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int base_id = 0;
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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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/*
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* make sure the module is enabled and clocked before reading
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* the module SYSSTATUS register
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*/
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devm_pm_runtime_enable(&pdev->dev);
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ret = pm_runtime_resume_and_get(&pdev->dev);
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if (ret < 0)
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return ret;
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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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/*
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* runtime PM will make sure the clock of this module is
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* enabled again iff at least one lock is requested
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*/
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ret = pm_runtime_put(&pdev->dev);
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if (ret < 0)
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return ret;
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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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return -EINVAL;
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num_locks = i * 32; /* actual number of locks in this device */
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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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for (i = 0; i < num_locks; i++)
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bank->lock[i].priv = io_base + LOCK_BASE_OFFSET + sizeof(u32) * i;
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return devm_hwspin_lock_register(&pdev->dev, bank, &omap_hwspinlock_ops,
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base_id, num_locks);
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}
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static const struct of_device_id omap_hwspinlock_of_match[] = {
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{ .compatible = "ti,omap4-hwspinlock", },
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{ .compatible = "ti,am64-hwspinlock", },
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{ .compatible = "ti,am654-hwspinlock", },
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{ /* end */ },
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};
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MODULE_DEVICE_TABLE(of, omap_hwspinlock_of_match);
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static struct platform_driver omap_hwspinlock_driver = {
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.probe = omap_hwspinlock_probe,
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.driver = {
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.name = "omap_hwspinlock",
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.of_match_table = omap_hwspinlock_of_match,
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},
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};
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static int __init omap_hwspinlock_init(void)
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{
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return platform_driver_register(&omap_hwspinlock_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(omap_hwspinlock_init);
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static void __exit omap_hwspinlock_exit(void)
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{
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platform_driver_unregister(&omap_hwspinlock_driver);
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}
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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>");
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