LXR linux/drivers/i2c/busses/i2c-designware-baytrail.c

   1// SPDX-License-Identifier: GPL-2.0
   2/*
   3 * Intel BayTrail PMIC I2C bus semaphore implementation
   4 * Copyright (c) 2014, Intel Corporation.
   5 */
   6#include <linux/device.h>
   7#include <linux/acpi.h>
   8#include <linux/i2c.h>
   9#include <linux/interrupt.h>
  10
  11#include <asm/iosf_mbi.h>
  12
  13#include "i2c-designware-core.h"
  14
  15int i2c_dw_probe_lock_support(struct dw_i2c_dev *dev)
  16{
  17        acpi_status status;
  18        unsigned long long shared_host = 0;
  19        acpi_handle handle;
  20
  21        if (!dev || !dev->dev)
  22                return 0;
  23
  24        handle = ACPI_HANDLE(dev->dev);
  25        if (!handle)
  26                return 0;
  27
  28        status = acpi_evaluate_integer(handle, "_SEM", NULL, &shared_host);
  29        if (ACPI_FAILURE(status))
  30                return 0;
  31
  32        if (!shared_host)
  33                return 0;
  34
  35        if (!iosf_mbi_available())
  36                return -EPROBE_DEFER;
  37
  38        dev_info(dev->dev, "I2C bus managed by PUNIT\n");
  39        dev->acquire_lock = iosf_mbi_block_punit_i2c_access;
  40        dev->release_lock = iosf_mbi_unblock_punit_i2c_access;
  41        dev->shared_with_punit = true;
  42
  43        return 0;
  44}
  45