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
  15 int 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 }