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https://github.com/AuxXxilium/linux_dsm_epyc7002.git
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acec09e67d
Some userspace drivers and frameworks only poll and do not require interrupts to be available and enabled on the PCI device. So remove the requirement that an IRQ is assigned. If an IRQ is not assigned and a userspace driver tries to read()/write(), the generic uio framework will just return -EIO. This allows binding uio_pci_generic to devices which cannot get an IRQ assigned, such as an NVMe controller behind Intel Volume Management Device (VMD), since VMD does not support INTx interrupts. Signed-off-by: Jim Harris <james.r.harris@intel.com> Acked-by: Michael S. Tsirkin <mst@redhat.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
127 lines
3.2 KiB
C
127 lines
3.2 KiB
C
/* uio_pci_generic - generic UIO driver for PCI 2.3 devices
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*
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* Copyright (C) 2009 Red Hat, Inc.
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* Author: Michael S. Tsirkin <mst@redhat.com>
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*
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* This work is licensed under the terms of the GNU GPL, version 2.
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*
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* Since the driver does not declare any device ids, you must allocate
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* id and bind the device to the driver yourself. For example:
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*
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* # echo "8086 10f5" > /sys/bus/pci/drivers/uio_pci_generic/new_id
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* # echo -n 0000:00:19.0 > /sys/bus/pci/drivers/e1000e/unbind
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* # echo -n 0000:00:19.0 > /sys/bus/pci/drivers/uio_pci_generic/bind
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* # ls -l /sys/bus/pci/devices/0000:00:19.0/driver
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* .../0000:00:19.0/driver -> ../../../bus/pci/drivers/uio_pci_generic
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*
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* Driver won't bind to devices which do not support the Interrupt Disable Bit
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* in the command register. All devices compliant to PCI 2.3 (circa 2002) and
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* all compliant PCI Express devices should support this bit.
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*/
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#include <linux/device.h>
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#include <linux/module.h>
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#include <linux/pci.h>
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#include <linux/slab.h>
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#include <linux/uio_driver.h>
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#define DRIVER_VERSION "0.01.0"
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#define DRIVER_AUTHOR "Michael S. Tsirkin <mst@redhat.com>"
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#define DRIVER_DESC "Generic UIO driver for PCI 2.3 devices"
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struct uio_pci_generic_dev {
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struct uio_info info;
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struct pci_dev *pdev;
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};
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static inline struct uio_pci_generic_dev *
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to_uio_pci_generic_dev(struct uio_info *info)
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{
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return container_of(info, struct uio_pci_generic_dev, info);
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}
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/* Interrupt handler. Read/modify/write the command register to disable
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* the interrupt. */
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static irqreturn_t irqhandler(int irq, struct uio_info *info)
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{
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struct uio_pci_generic_dev *gdev = to_uio_pci_generic_dev(info);
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if (!pci_check_and_mask_intx(gdev->pdev))
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return IRQ_NONE;
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/* UIO core will signal the user process. */
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return IRQ_HANDLED;
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}
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static int probe(struct pci_dev *pdev,
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const struct pci_device_id *id)
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{
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struct uio_pci_generic_dev *gdev;
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int err;
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err = pci_enable_device(pdev);
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if (err) {
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dev_err(&pdev->dev, "%s: pci_enable_device failed: %d\n",
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__func__, err);
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return err;
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}
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if (pdev->irq && !pci_intx_mask_supported(pdev)) {
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err = -ENODEV;
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goto err_verify;
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}
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gdev = kzalloc(sizeof(struct uio_pci_generic_dev), GFP_KERNEL);
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if (!gdev) {
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err = -ENOMEM;
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goto err_alloc;
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}
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gdev->info.name = "uio_pci_generic";
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gdev->info.version = DRIVER_VERSION;
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gdev->pdev = pdev;
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if (pdev->irq) {
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gdev->info.irq = pdev->irq;
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gdev->info.irq_flags = IRQF_SHARED;
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gdev->info.handler = irqhandler;
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} else {
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dev_warn(&pdev->dev, "No IRQ assigned to device: "
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"no support for interrupts?\n");
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}
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err = uio_register_device(&pdev->dev, &gdev->info);
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if (err)
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goto err_register;
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pci_set_drvdata(pdev, gdev);
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return 0;
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err_register:
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kfree(gdev);
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err_alloc:
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err_verify:
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pci_disable_device(pdev);
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return err;
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}
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static void remove(struct pci_dev *pdev)
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{
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struct uio_pci_generic_dev *gdev = pci_get_drvdata(pdev);
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uio_unregister_device(&gdev->info);
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pci_disable_device(pdev);
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kfree(gdev);
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}
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static struct pci_driver uio_pci_driver = {
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.name = "uio_pci_generic",
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.id_table = NULL, /* only dynamic id's */
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.probe = probe,
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.remove = remove,
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};
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module_pci_driver(uio_pci_driver);
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MODULE_VERSION(DRIVER_VERSION);
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MODULE_LICENSE("GPL v2");
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MODULE_AUTHOR(DRIVER_AUTHOR);
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MODULE_DESCRIPTION(DRIVER_DESC);
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