Quelle  i2c-designware-baytrail.c   Sprache: C

// SPDX-License-Identifier: GPL-2.0
/*
 * Intel BayTrail PMIC I2C bus semaphore implementation
 * Copyright (c) 2014, Intel Corporation.
 */
#include <linux/device.h>
#include <linux/acpi.h>
#include <linux/i2c.h>
#include <linux/interrupt.h>

#include <asm/iosf_mbi.h>

#include "i2c-designware-core.h"

int i2c_dw_baytrail_probe_lock_support(struct dw_i2c_dev *dev)
{
 acpi_status status;
 unsigned long long shared_host = 0;
 acpi_handle handle;

 if (!dev)
  return -ENODEV;

 handle = ACPI_HANDLE(dev->dev);
 if (!handle)
  return -ENODEV;

 status = acpi_evaluate_integer(handle, "_SEM", NULL, &shared_host);
 if (ACPI_FAILURE(status))
  return -ENODEV;

 if (!shared_host)
  return -ENODEV;

 if (!iosf_mbi_available())
  return -EPROBE_DEFER;

 dev_info(dev->dev, "I2C bus managed by PUNIT\n");
 dev->acquire_lock = iosf_mbi_block_punit_i2c_access;
 dev->release_lock = iosf_mbi_unblock_punit_i2c_access;
 dev->shared_with_punit = true;

 return 0;
}