drivers/misc/mei/pci-csc.c

// SPDX-License-Identifier: GPL-2.0
/*
 * Copyright (C) 2025-2026, Intel Corporation. All rights reserved.
 * Intel Management Engine Interface (Intel MEI) Linux driver
 * for CSC platforms.
 */

#include <linux/cleanup.h>
#include <linux/device.h>
#include <linux/dma-mapping.h>
#include <linux/err.h>
#include <linux/errno.h>
#include <linux/interrupt.h>
#include <linux/module.h>
#include <linux/mutex.h>
#include <linux/pci.h>
#include <linux/pm_runtime.h>
#include <linux/sched.h>
#include <linux/types.h>

#include "client.h"
#include "hw-me-regs.h"
#include "hw-me.h"
#include "mei_dev.h"
#include "mei-trace.h"

#define MEI_CSC_HECI2_OFFSET 0x1000

static int mei_csc_read_fws(const struct mei_device *mdev, int where, const char *name, u32 *val)
{
	struct mei_me_hw *hw = to_me_hw(mdev);

	*val = ioread32(hw->mem_addr + where + 0xC00);
	trace_mei_reg_read(&mdev->dev, name, where, *val);
	return 0;
}

static int mei_csc_probe(struct pci_dev *pdev, const struct pci_device_id *ent)
{
	struct device *dev = &pdev->dev;
	const struct mei_cfg *cfg;
	char __iomem *registers;
	struct mei_device *mdev;
	struct mei_me_hw *hw;
	int err;

	cfg = mei_me_get_cfg(ent->driver_data);
	if (!cfg)
		return -ENODEV;

	err = pcim_enable_device(pdev);
	if (err)
		return dev_err_probe(dev, err, "Failed to enable PCI device.\n");

	pci_set_master(pdev);

	registers = pcim_iomap_region(pdev, 0, KBUILD_MODNAME);
	if (IS_ERR(registers))
		return dev_err_probe(dev, PTR_ERR(registers), "Failed to get PCI region.\n");

	err = dma_set_mask_and_coherent(dev, DMA_BIT_MASK(64));
	if (err)
		return dev_err_probe(dev, err, "No usable DMA configuration.\n");

	/* allocates and initializes the mei dev structure */
	mdev = mei_me_dev_init(dev, cfg, false);
	if (!mdev)
		return -ENOMEM;

	mdev->read_fws_need_resume = true;

	hw = to_me_hw(mdev);

	/*
	 * Both HECI1 and HECI2 are on this device, but only HECI2 is supported.
	 */
	hw->mem_addr = registers + MEI_CSC_HECI2_OFFSET;
	hw->read_fws = mei_csc_read_fws;

	/*
	 * mei_register() assumes ownership of mdev.
	 * No need to release it explicitly in error path.
	 */
	err = mei_register(mdev, dev);
	if (err)
		return err;

	pci_set_drvdata(pdev, mdev);

	err = pci_alloc_irq_vectors(pdev, 1, 1, PCI_IRQ_INTX | PCI_IRQ_MSI);
	if (err < 0) {
		dev_err_probe(dev, err, "Failed to allocate IRQ.\n");
		goto err_mei_unreg;
	}

	hw->irq = pci_irq_vector(pdev, 0);

	/* request and enable interrupt */
	err = request_threaded_irq(hw->irq,
				   mei_me_irq_quick_handler, mei_me_irq_thread_handler,
				   IRQF_SHARED | IRQF_ONESHOT, KBUILD_MODNAME, mdev);
	if (err)
		goto err_free_irq_vectors;

	/*
	 * Continue to char device setup in spite of firmware handshake failure.
	 * In order to provide access to the firmware status registers to the user
	 * space via sysfs. The firmware status registers required to understand
	 * firmware error state and possible recovery flow.
	 */
	if (mei_start(mdev))
		dev_warn(dev, "Failed to initialize HECI hardware.\n");

	pm_runtime_set_autosuspend_delay(dev, MEI_ME_RPM_TIMEOUT);
	pm_runtime_use_autosuspend(dev);

	/*
	 * MEI requires to resume from runtime suspend mode
	 * in order to perform link reset flow upon system suspend.
	 */
	dev_pm_set_driver_flags(dev, DPM_FLAG_NO_DIRECT_COMPLETE);

	pm_runtime_allow(dev);
	pm_runtime_put_noidle(dev);

	return 0;

err_free_irq_vectors:
	pci_free_irq_vectors(pdev);
err_mei_unreg:
	mei_deregister(mdev);
	return err;
}

static void mei_csc_shutdown(struct pci_dev *pdev)
{
	struct mei_device *mdev = pci_get_drvdata(pdev);
	struct mei_me_hw *hw = to_me_hw(mdev);

	pm_runtime_get_noresume(&pdev->dev);

	mei_stop(mdev);

	mei_disable_interrupts(mdev);
	free_irq(hw->irq, mdev);
	pci_free_irq_vectors(pdev);
}

static void mei_csc_remove(struct pci_dev *pdev)
{
	struct mei_device *mdev = pci_get_drvdata(pdev);

	mei_csc_shutdown(pdev);

	mei_deregister(mdev);
}

static int mei_csc_pci_prepare(struct device *dev)
{
	pm_runtime_resume(dev);
	return 0;
}

static int mei_csc_pci_suspend(struct device *dev)
{
	struct mei_device *mdev = dev_get_drvdata(dev);

	mei_stop(mdev);

	mei_disable_interrupts(mdev);

	return 0;
}

static int mei_csc_pci_resume(struct device *dev)
{
	struct mei_device *mdev = dev_get_drvdata(dev);
	int err;

	err = mei_restart(mdev);
	if (err)
		return err;

	/* Start timer if stopped in suspend */
	schedule_delayed_work(&mdev->timer_work, HZ);

	return 0;
}

static void mei_csc_pci_complete(struct device *dev)
{
	pm_runtime_suspend(dev);
}

static int mei_csc_pm_runtime_idle(struct device *dev)
{
	struct mei_device *mdev = dev_get_drvdata(dev);

	return mei_write_is_idle(mdev) ? 0 : -EBUSY;
}

static int mei_csc_pm_runtime_suspend(struct device *dev)
{
	struct mei_device *mdev = dev_get_drvdata(dev);
	struct mei_me_hw *hw = to_me_hw(mdev);

	guard(mutex)(&mdev->device_lock);

	if (!mei_write_is_idle(mdev))
		return -EAGAIN;

	hw->pg_state = MEI_PG_ON;
	return 0;
}

static int mei_csc_pm_runtime_resume(struct device *dev)
{
	struct mei_device *mdev = dev_get_drvdata(dev);
	struct mei_me_hw *hw = to_me_hw(mdev);
	irqreturn_t irq_ret;

	scoped_guard(mutex, &mdev->device_lock)
		hw->pg_state = MEI_PG_OFF;

	/* Process all queues that wait for resume */
	irq_ret = mei_me_irq_thread_handler(1, mdev);
	if (irq_ret != IRQ_HANDLED)
		dev_err(dev, "thread handler fail %d\n", irq_ret);

	return 0;
}

static const struct dev_pm_ops mei_csc_pm_ops = {
	.prepare = pm_sleep_ptr(mei_csc_pci_prepare),
	.complete = pm_sleep_ptr(mei_csc_pci_complete),
	SYSTEM_SLEEP_PM_OPS(mei_csc_pci_suspend, mei_csc_pci_resume)
	RUNTIME_PM_OPS(mei_csc_pm_runtime_suspend,
		       mei_csc_pm_runtime_resume, mei_csc_pm_runtime_idle)
};

static const struct pci_device_id mei_csc_pci_tbl[] = {
	{ PCI_DEVICE_DATA(INTEL, MEI_CRI, MEI_ME_CSC_CFG) },
	{ }
};
MODULE_DEVICE_TABLE(pci, mei_csc_pci_tbl);

static struct pci_driver mei_csc_driver = {
	.name = KBUILD_MODNAME,
	.id_table = mei_csc_pci_tbl,
	.probe = mei_csc_probe,
	.remove = mei_csc_remove,
	.shutdown = mei_csc_shutdown,
	.driver = {
		.pm = &mei_csc_pm_ops,
		.probe_type = PROBE_PREFER_ASYNCHRONOUS,
	}
};
module_pci_driver(mei_csc_driver);

MODULE_DESCRIPTION("Intel(R) Management Engine Interface for discrete graphics (CSC)");
MODULE_LICENSE("GPL");