path: root/drivers/pci/hotplug/pciehp_hpc.c

// SPDX-License-Identifier: GPL-2.0+
/*
 * PCI Express PCI Hot Plug Driver
 *
 * Copyright (C) 1995,2001 Compaq Computer Corporation
 * Copyright (C) 2001 Greg Kroah-Hartman (greg@kroah.com)
 * Copyright (C) 2001 IBM Corp.
 * Copyright (C) 2003-2004 Intel Corporation
 *
 * All rights reserved.
 *
 * Send feedback to <greg@kroah.com>,<kristen.c.accardi@intel.com>
 */

#define dev_fmt(fmt) "pciehp: " fmt

#include <linux/dmi.h>
#include <linux/kernel.h>
#include <linux/types.h>
#include <linux/jiffies.h>
#include <linux/kthread.h>
#include <linux/pci.h>
#include <linux/pm_runtime.h>
#include <linux/interrupt.h>
#include <linux/slab.h>

#include "../pci.h"
#include "pciehp.h"

static const struct dmi_system_id inband_presence_disabled_dmi_table[] = {
	/*
	 * Match all Dell systems, as some Dell systems have inband
	 * presence disabled on NVMe slots (but don't support the bit to
	 * report it). Setting inband presence disabled should have no
	 * negative effect, except on broken hotplug slots that never
	 * assert presence detect--and those will still work, they will
	 * just have a bit of extra delay before being probed.
	 */
	{
		.ident = "Dell System",
		.matches = {
			DMI_MATCH(DMI_OEM_STRING, "Dell System"),
		},
	},
	{}
};

static inline struct pci_dev *ctrl_dev(struct controller *ctrl)
{
	return ctrl->pcie->port;
}

static irqreturn_t pciehp_isr(int irq, void *dev_id);
static irqreturn_t pciehp_ist(int irq, void *dev_id);
static int pciehp_poll(void *data);

static inline int pciehp_request_irq(struct controller *ctrl)
{
	int retval, irq = ctrl->pcie->irq;

	if (pciehp_poll_mode) {
		ctrl->poll_thread = kthread_run(&pciehp_poll, ctrl,
						"pciehp_poll-%s",
						slot_name(ctrl));
		return PTR_ERR_OR_ZERO(ctrl->poll_thread);
	}

	/* Installs the interrupt handler */
	retval = request_threaded_irq(irq, pciehp_isr, pciehp_ist,
				      IRQF_SHARED, "pciehp", ctrl);
	if (retval)
		ctrl_err(ctrl, "Cannot get irq %d for the hotplug controller\n",
			 irq);
	return retval;
}

static inline void pciehp_free_irq(struct controller *ctrl)
{
	if (pciehp_poll_mode)
		kthread_stop(ctrl->poll_thread);
	else
		free_irq(ctrl->pcie->irq, ctrl);
}

static int pcie_poll_cmd(struct controller *ctrl, int timeout)
{
	struct pci_dev *pdev = ctrl_dev(ctrl);
	u16 slot_status;

	do {
		pcie_capability_read_word(pdev, PCI_EXP_SLTSTA, &slot_status);
		if (PCI_POSSIBLE_ERROR(slot_status)) {
			ctrl_info(ctrl, "%s: no response from device\n",
				  __func__);
			return 0;
		}

		if (slot_status & PCI_EXP_SLTSTA_CC) {
			pcie_capability_write_word(pdev, PCI_EXP_SLTSTA,
						   PCI_EXP_SLTSTA_CC);
			ctrl->cmd_busy = 0;
			smp_mb();
			return 1;
		}
		msleep(10);
		timeout -= 10;
	} while (timeout >= 0);
	return 0;	/* timeout */
}

static void pcie_wait_cmd(struct controller *ctrl)
{
	unsigned int msecs = pciehp_poll_mode ? 2500 : 1000;
	unsigned long duration = msecs_to_jiffies(msecs);
	unsigned long cmd_timeout = ctrl->cmd_started + duration;
	unsigned long now, timeout;
	int rc;

	/*
	 * If the controller does not generate notifications for command
	 * completions, we never need to wait between writes.
	 */
	if (NO_CMD_CMPL(ctrl))
		return;

	if (!ctrl->cmd_busy)
		return;

	/*
	 * Even if the command has already timed out, we want to call
	 * pcie_poll_cmd() so it can clear PCI_EXP_SLTSTA_CC.
	 */
	now = jiffies;
	if (time_before_eq(cmd_timeout, now))
		timeout = 1;
	else
		timeout = cmd_timeout - now;

	if (ctrl->slot_ctrl & PCI_EXP_SLTCTL_HPIE &&
	    ctrl->slot_ctrl & PCI_EXP_SLTCTL_CCIE)
		rc = wait_event_timeout(ctrl->queue, !ctrl->cmd_busy, timeout);
	else
		rc = pcie_poll_cmd(ctrl, jiffies_to_msecs(timeout));

	if (!rc)
		ctrl_info(ctrl, "Timeout on hotplug command %#06x (issued %u msec ago)\n",
			  ctrl->slot_ctrl,
			  jiffies_to_msecs(jiffies - ctrl->cmd_started));
}

#define CC_ERRATUM_MASK		(PCI_EXP_SLTCTL_PCC |	\
				 PCI_EXP_SLTCTL_PIC |	\
				 PCI_EXP_SLTCTL_AIC |	\
				 PCI_EXP_SLTCTL_EIC)

static void pcie_do_write_cmd(struct controller *ctrl, u16 cmd,
			      u16 mask, bool wait)
{
	struct pci_dev *pdev = ctrl_dev(ctrl);
	u16 slot_ctrl_orig, slot_ctrl;

	mutex_lock(&ctrl->ctrl_lock);

	/*
	 * Always wait for any previous command that might still be in progress
	 */
	pcie_wait_cmd(ctrl);

	pcie_capability_read_word(pdev, PCI_EXP_SLTCTL, &slot_ctrl);
	if (PCI_POSSIBLE_ERROR(slot_ctrl)) {
		ctrl_info(ctrl, "%s: no response from device\n", __func__);
		goto out;
	}

	slot_ctrl_orig = slot_ctrl;
	slot_ctrl &= ~