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1// SPDX-License-Identifier: GPL-2.02/*3 * OMAP hardware spinlock driver4 *5 * Copyright (C) 2010-2021 Texas Instruments Incorporated - https://www.ti.com6 *7 * Contact: Simon Que <sque@ti.com>8 * Hari Kanigeri <h-kanigeri2@ti.com>9 * Ohad Ben-Cohen <ohad@wizery.com>10 * Suman Anna <s-anna@ti.com>11 */12 13#include <linux/kernel.h>14#include <linux/module.h>15#include <linux/device.h>16#include <linux/delay.h>17#include <linux/io.h>18#include <linux/bitops.h>19#include <linux/pm_runtime.h>20#include <linux/slab.h>21#include <linux/spinlock.h>22#include <linux/hwspinlock.h>23#include <linux/of.h>24#include <linux/platform_device.h>25 26#include "hwspinlock_internal.h"27 28/* Spinlock register offsets */29#define SYSSTATUS_OFFSET 0x001430#define LOCK_BASE_OFFSET 0x080031 32#define SPINLOCK_NUMLOCKS_BIT_OFFSET (24)33 34/* Possible values of SPINLOCK_LOCK_REG */35#define SPINLOCK_NOTTAKEN (0) /* free */36#define SPINLOCK_TAKEN (1) /* locked */37 38static int omap_hwspinlock_trylock(struct hwspinlock *lock)39{40 void __iomem *lock_addr = lock->priv;41 42 /* attempt to acquire the lock by reading its value */43 return (SPINLOCK_NOTTAKEN == readl(lock_addr));44}45 46static void omap_hwspinlock_unlock(struct hwspinlock *lock)47{48 void __iomem *lock_addr = lock->priv;49 50 /* release the lock by writing 0 to it */51 writel(SPINLOCK_NOTTAKEN, lock_addr);52}53 54/*55 * relax the OMAP interconnect while spinning on it.56 *57 * The specs recommended that the retry delay time will be58 * just over half of the time that a requester would be59 * expected to hold the lock.60 *61 * The number below is taken from an hardware specs example,62 * obviously it is somewhat arbitrary.63 */64static void omap_hwspinlock_relax(struct hwspinlock *lock)65{66 ndelay(50);67}68 69static const struct hwspinlock_ops omap_hwspinlock_ops = {70 .trylock = omap_hwspinlock_trylock,71 .unlock = omap_hwspinlock_unlock,72 .relax = omap_hwspinlock_relax,73};74 75static int omap_hwspinlock_probe(struct platform_device *pdev)76{77 struct hwspinlock_device *bank;78 void __iomem *io_base;79 int num_locks, i, ret;80 /* Only a single hwspinlock block device is supported */81 int base_id = 0;82 83 io_base = devm_platform_ioremap_resource(pdev, 0);84 if (IS_ERR(io_base))85 return PTR_ERR(io_base);86 87 /*88 * make sure the module is enabled and clocked before reading89 * the module SYSSTATUS register90 */91 devm_pm_runtime_enable(&pdev->dev);92 ret = pm_runtime_resume_and_get(&pdev->dev);93 if (ret < 0)94 return ret;95 96 /* Determine number of locks */97 i = readl(io_base + SYSSTATUS_OFFSET);98 i >>= SPINLOCK_NUMLOCKS_BIT_OFFSET;99 100 /*101 * runtime PM will make sure the clock of this module is102 * enabled again iff at least one lock is requested103 */104 ret = pm_runtime_put(&pdev->dev);105 if (ret < 0)106 return ret;107 108 /* one of the four lsb's must be set, and nothing else */109 if (hweight_long(i & 0xf) != 1 || i > 8)110 return -EINVAL;111 112 num_locks = i * 32; /* actual number of locks in this device */113 114 bank = devm_kzalloc(&pdev->dev, struct_size(bank, lock, num_locks),115 GFP_KERNEL);116 if (!bank)117 return -ENOMEM;118 119 for (i = 0; i < num_locks; i++)120 bank->lock[i].priv = io_base + LOCK_BASE_OFFSET + sizeof(u32) * i;121 122 return devm_hwspin_lock_register(&pdev->dev, bank, &omap_hwspinlock_ops,123 base_id, num_locks);124}125 126static const struct of_device_id omap_hwspinlock_of_match[] = {127 { .compatible = "ti,omap4-hwspinlock", },128 { .compatible = "ti,am64-hwspinlock", },129 { .compatible = "ti,am654-hwspinlock", },130 { /* end */ },131};132MODULE_DEVICE_TABLE(of, omap_hwspinlock_of_match);133 134static struct platform_driver omap_hwspinlock_driver = {135 .probe = omap_hwspinlock_probe,136 .driver = {137 .name = "omap_hwspinlock",138 .of_match_table = omap_hwspinlock_of_match,139 },140};141 142static int __init omap_hwspinlock_init(void)143{144 return platform_driver_register(&omap_hwspinlock_driver);145}146/* board init code might need to reserve hwspinlocks for predefined purposes */147postcore_initcall(omap_hwspinlock_init);148 149static void __exit omap_hwspinlock_exit(void)150{151 platform_driver_unregister(&omap_hwspinlock_driver);152}153module_exit(omap_hwspinlock_exit);154 155MODULE_LICENSE("GPL v2");156MODULE_DESCRIPTION("Hardware spinlock driver for OMAP");157MODULE_AUTHOR("Simon Que <sque@ti.com>");158MODULE_AUTHOR("Hari Kanigeri <h-kanigeri2@ti.com>");159MODULE_AUTHOR("Ohad Ben-Cohen <ohad@wizery.com>");160