c2101d0182
Pull more ACPI updates from Rafael Wysocki: "Rework the handling of the P-unit semaphore on Intel Baytrail and Cherrytrail systems to avoid race conditions and excessive overhead related to it (Hans de Goede)" * tag 'acpi-4.20-rc1-2' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm: ACPI / PMIC: xpower: Add depends on IOSF_MBI to Kconfig entry i2c: designware: Cleanup bus lock handling ACPI / PMIC: xpower: Block P-Unit I2C access during read-modify-write x86: baytrail/cherrytrail: Rework and move P-Unit PMIC bus semaphore code
45 lines
938 B
C
45 lines
938 B
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* Intel BayTrail PMIC I2C bus semaphore implementaion
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* Copyright (c) 2014, Intel Corporation.
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*/
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#include <linux/device.h>
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#include <linux/acpi.h>
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#include <linux/i2c.h>
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#include <linux/interrupt.h>
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#include <asm/iosf_mbi.h>
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#include "i2c-designware-core.h"
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int i2c_dw_probe_lock_support(struct dw_i2c_dev *dev)
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{
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acpi_status status;
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unsigned long long shared_host = 0;
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acpi_handle handle;
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if (!dev || !dev->dev)
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return 0;
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handle = ACPI_HANDLE(dev->dev);
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if (!handle)
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return 0;
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status = acpi_evaluate_integer(handle, "_SEM", NULL, &shared_host);
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if (ACPI_FAILURE(status))
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return 0;
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if (!shared_host)
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return 0;
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if (!iosf_mbi_available())
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return -EPROBE_DEFER;
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dev_info(dev->dev, "I2C bus managed by PUNIT\n");
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dev->acquire_lock = iosf_mbi_block_punit_i2c_access;
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dev->release_lock = iosf_mbi_unblock_punit_i2c_access;
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dev->shared_with_punit = true;
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return 0;
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}
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