linux/drivers/hwspinlock/stm32_hwspinlock.c
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   1// SPDX-License-Identifier: GPL-2.0
   2/*
   3 * Copyright (C) STMicroelectronics SA 2018
   4 * Author: Benjamin Gaignard <benjamin.gaignard@st.com> for STMicroelectronics.
   5 */
   6
   7#include <linux/clk.h>
   8#include <linux/delay.h>
   9#include <linux/hwspinlock.h>
  10#include <linux/io.h>
  11#include <linux/kernel.h>
  12#include <linux/module.h>
  13#include <linux/of.h>
  14#include <linux/platform_device.h>
  15#include <linux/pm_runtime.h>
  16
  17#include "hwspinlock_internal.h"
  18
  19#define STM32_MUTEX_COREID      BIT(8)
  20#define STM32_MUTEX_LOCK_BIT    BIT(31)
  21#define STM32_MUTEX_NUM_LOCKS   32
  22
  23struct stm32_hwspinlock {
  24        struct clk *clk;
  25        struct hwspinlock_device bank;
  26};
  27
  28static int stm32_hwspinlock_trylock(struct hwspinlock *lock)
  29{
  30        void __iomem *lock_addr = lock->priv;
  31        u32 status;
  32
  33        writel(STM32_MUTEX_LOCK_BIT | STM32_MUTEX_COREID, lock_addr);
  34        status = readl(lock_addr);
  35
  36        return status == (STM32_MUTEX_LOCK_BIT | STM32_MUTEX_COREID);
  37}
  38
  39static void stm32_hwspinlock_unlock(struct hwspinlock *lock)
  40{
  41        void __iomem *lock_addr = lock->priv;
  42
  43        writel(STM32_MUTEX_COREID, lock_addr);
  44}
  45
  46static void stm32_hwspinlock_relax(struct hwspinlock *lock)
  47{
  48        ndelay(50);
  49}
  50
  51static const struct hwspinlock_ops stm32_hwspinlock_ops = {
  52        .trylock        = stm32_hwspinlock_trylock,
  53        .unlock         = stm32_hwspinlock_unlock,
  54        .relax          = stm32_hwspinlock_relax,
  55};
  56
  57static int stm32_hwspinlock_probe(struct platform_device *pdev)
  58{
  59        struct stm32_hwspinlock *hw;
  60        void __iomem *io_base;
  61        size_t array_size;
  62        int i, ret;
  63
  64        io_base = devm_platform_ioremap_resource(pdev, 0);
  65        if (IS_ERR(io_base))
  66                return PTR_ERR(io_base);
  67
  68        array_size = STM32_MUTEX_NUM_LOCKS * sizeof(struct hwspinlock);
  69        hw = devm_kzalloc(&pdev->dev, sizeof(*hw) + array_size, GFP_KERNEL);
  70        if (!hw)
  71                return -ENOMEM;
  72
  73        hw->clk = devm_clk_get(&pdev->dev, "hsem");
  74        if (IS_ERR(hw->clk))
  75                return PTR_ERR(hw->clk);
  76
  77        for (i = 0; i < STM32_MUTEX_NUM_LOCKS; i++)
  78                hw->bank.lock[i].priv = io_base + i * sizeof(u32);
  79
  80        platform_set_drvdata(pdev, hw);
  81        pm_runtime_enable(&pdev->dev);
  82
  83        ret = hwspin_lock_register(&hw->bank, &pdev->dev, &stm32_hwspinlock_ops,
  84                                   0, STM32_MUTEX_NUM_LOCKS);
  85
  86        if (ret)
  87                pm_runtime_disable(&pdev->dev);
  88
  89        return ret;
  90}
  91
  92static int stm32_hwspinlock_remove(struct platform_device *pdev)
  93{
  94        struct stm32_hwspinlock *hw = platform_get_drvdata(pdev);
  95        int ret;
  96
  97        ret = hwspin_lock_unregister(&hw->bank);
  98        if (ret)
  99                dev_err(&pdev->dev, "%s failed: %d\n", __func__, ret);
 100
 101        pm_runtime_disable(&pdev->dev);
 102
 103        return 0;
 104}
 105
 106static int __maybe_unused stm32_hwspinlock_runtime_suspend(struct device *dev)
 107{
 108        struct stm32_hwspinlock *hw = dev_get_drvdata(dev);
 109
 110        clk_disable_unprepare(hw->clk);
 111
 112        return 0;
 113}
 114
 115static int __maybe_unused stm32_hwspinlock_runtime_resume(struct device *dev)
 116{
 117        struct stm32_hwspinlock *hw = dev_get_drvdata(dev);
 118
 119        clk_prepare_enable(hw->clk);
 120
 121        return 0;
 122}
 123
 124static const struct dev_pm_ops stm32_hwspinlock_pm_ops = {
 125        SET_RUNTIME_PM_OPS(stm32_hwspinlock_runtime_suspend,
 126                           stm32_hwspinlock_runtime_resume,
 127                           NULL)
 128};
 129
 130static const struct of_device_id stm32_hwpinlock_ids[] = {
 131        { .compatible = "st,stm32-hwspinlock", },
 132        {},
 133};
 134MODULE_DEVICE_TABLE(of, stm32_hwpinlock_ids);
 135
 136static struct platform_driver stm32_hwspinlock_driver = {
 137        .probe          = stm32_hwspinlock_probe,
 138        .remove         = stm32_hwspinlock_remove,
 139        .driver         = {
 140                .name   = "stm32_hwspinlock",
 141                .of_match_table = stm32_hwpinlock_ids,
 142                .pm     = &stm32_hwspinlock_pm_ops,
 143        },
 144};
 145
 146static int __init stm32_hwspinlock_init(void)
 147{
 148        return platform_driver_register(&stm32_hwspinlock_driver);
 149}
 150/* board init code might need to reserve hwspinlocks for predefined purposes */
 151postcore_initcall(stm32_hwspinlock_init);
 152
 153static void __exit stm32_hwspinlock_exit(void)
 154{
 155        platform_driver_unregister(&stm32_hwspinlock_driver);
 156}
 157module_exit(stm32_hwspinlock_exit);
 158
 159MODULE_LICENSE("GPL v2");
 160MODULE_DESCRIPTION("Hardware spinlock driver for STM32 SoCs");
 161MODULE_AUTHOR("Benjamin Gaignard <benjamin.gaignard@st.com>");
 162
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