i2c/busses/i2c-designware-baytrail.c

0001 // SPDX-License-Identifier: GPL-2.0
0002 /*
0003  * Intel BayTrail PMIC I2C bus semaphore implementation
0004  * Copyright (c) 2014, Intel Corporation.
0005  */
0006 #include <linux/device.h>
0007 #include <linux/acpi.h>
0008 #include <linux/i2c.h>
0009 #include <linux/interrupt.h>
0010
0011 #include <asm/iosf_mbi.h>
0012
0013 #include "i2c-designware-core.h"
0014
0015 int i2c_dw_baytrail_probe_lock_support(struct dw_i2c_dev *dev)
0016 {
0017     acpi_status status;
0018     unsigned long long shared_host = 0;
0019     acpi_handle handle;
0020
0021     if (!dev)
0022         return -ENODEV;
0023
0024     handle = ACPI_HANDLE(dev->dev);
0025     if (!handle)
0026         return -ENODEV;
0027
0028     status = acpi_evaluate_integer(handle, "_SEM", NULL, &shared_host);
0029     if (ACPI_FAILURE(status))
0030         return -ENODEV;
0031
0032     if (!shared_host)
0033         return -ENODEV;
0034
0035     if (!iosf_mbi_available())
0036         return -EPROBE_DEFER;
0037
0038     dev_info(dev->dev, "I2C bus managed by PUNIT\n");
0039     dev->acquire_lock = iosf_mbi_block_punit_i2c_access;
0040     dev->release_lock = iosf_mbi_unblock_punit_i2c_access;
0041     dev->shared_with_punit = true;
0042
0043     return 0;
0044 }