linux-imx

// SPDX-License-Identifier: GPL-2.0

/*

 * u8500 HWSEM driver

 *

 * Copyright (C) 2010-2011 ST-Ericsson

 *

 * Implements u8500 semaphore handling for protocol 1, no interrupts.

 *

 * Author: Mathieu Poirier <mathieu.poirier@linaro.org>

 * Heavily borrowed from the work of :

 *   Simon Que <sque@ti.com>

 *   Hari Kanigeri <h-kanigeri2@ti.com>

 *   Ohad Ben-Cohen <ohad@wizery.com>

 */

​

#include <linux/module.h>

#include <linux/delay.h>

#include <linux/io.h>

#include <linux/pm_runtime.h>

#include <linux/slab.h>

#include <linux/spinlock.h>

#include <linux/hwspinlock.h>

#include <linux/platform_device.h>

​

#include "hwspinlock_internal.h"

​

/*

 * Implementation of STE's HSem protocol 1 without interrutps.

 * The only masterID we allow is '0x01' to force people to use

 * HSems for synchronisation between processors rather than processes

 * on the ARM core.

 */

​

#define U8500_MAX_SEMAPHORE     32  /* a total of 32 semaphore */

#define RESET_SEMAPHORE         (0) /* free */

​

/*

 * CPU ID for master running u8500 kernel.

 * Hswpinlocks should only be used to synchonise operations

 * between the Cortex A9 core and the other CPUs.  Hence

 * forcing the masterID to a preset value.

 */

#define HSEM_MASTER_ID          0x01

​

#define HSEM_REGISTER_OFFSET        0x08

​

#define HSEM_CTRL_REG           0x00

#define HSEM_ICRALL         0x90

#define HSEM_PROTOCOL_1         0x01

​

static int u8500_hsem_trylock(struct hwspinlock *lock)

{

    void __iomem *lock_addr = lock->priv;

​

    writel(HSEM_MASTER_ID, lock_addr);

​

    /* get only first 4 bit and compare to masterID.

     * if equal, we have the semaphore, otherwise

     * someone else has it.

     */

    return (HSEM_MASTER_ID == (0x0F & readl(lock_addr)));

}

​