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@@ -0,0 +1,207 @@
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+/* 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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+
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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/uio_driver.h>
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+#include <linux/spinlock.h>
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+
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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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+
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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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+ spinlock_t lock; /* guards command register accesses */
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+};
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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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+
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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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+ struct pci_dev *pdev = gdev->pdev;
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+ irqreturn_t ret = IRQ_NONE;
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+ u32 cmd_status_dword;
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+ u16 origcmd, newcmd, status;
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+
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+ /* We do a single dword read to retrieve both command and status.
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+ * Document assumptions that make this possible. */
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+ BUILD_BUG_ON(PCI_COMMAND % 4);
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+ BUILD_BUG_ON(PCI_COMMAND + 2 != PCI_STATUS);
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+
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+ spin_lock_irq(&gdev->lock);
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+ pci_block_user_cfg_access(pdev);
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+
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+ /* Read both command and status registers in a single 32-bit operation.
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+ * Note: we could cache the value for command and move the status read
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+ * out of the lock if there was a way to get notified of user changes
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+ * to command register through sysfs. Should be good for shared irqs. */
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+ pci_read_config_dword(pdev, PCI_COMMAND, &cmd_status_dword);
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+ origcmd = cmd_status_dword;
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+ status = cmd_status_dword >> 16;
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+
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+ /* Check interrupt status register to see whether our device
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+ * triggered the interrupt. */
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+ if (!(status & PCI_STATUS_INTERRUPT))
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+ goto done;
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+
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+ /* We triggered the interrupt, disable it. */
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+ newcmd = origcmd | PCI_COMMAND_INTX_DISABLE;
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+ if (newcmd != origcmd)
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+ pci_write_config_word(pdev, PCI_COMMAND, newcmd);
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+
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+ /* UIO core will signal the user process. */
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+ ret = IRQ_HANDLED;
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+done:
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+
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+ pci_unblock_user_cfg_access(pdev);
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+ spin_unlock_irq(&gdev->lock);
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+ return ret;
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+}
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+
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+/* Verify that the device supports Interrupt Disable bit in command register,
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+ * per PCI 2.3, by flipping this bit and reading it back: this bit was readonly
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+ * in PCI 2.2. */
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+static int __devinit verify_pci_2_3(struct pci_dev *pdev)
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+{
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+ u16 orig, new;
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+ int err = 0;
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+
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+ pci_block_user_cfg_access(pdev);
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+ pci_read_config_word(pdev, PCI_COMMAND, &orig);
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+ pci_write_config_word(pdev, PCI_COMMAND,
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+ orig ^ PCI_COMMAND_INTX_DISABLE);
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+ pci_read_config_word(pdev, PCI_COMMAND, &new);
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+ /* There's no way to protect against
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+ * hardware bugs or detect them reliably, but as long as we know
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+ * what the value should be, let's go ahead and check it. */
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+ if ((new ^ orig) & ~PCI_COMMAND_INTX_DISABLE) {
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+ err = -EBUSY;
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+ dev_err(&pdev->dev, "Command changed from 0x%x to 0x%x: "
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+ "driver or HW bug?\n", orig, new);
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+ goto err;
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+ }
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+ if (!((new ^ orig) & PCI_COMMAND_INTX_DISABLE)) {
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+ dev_warn(&pdev->dev, "Device does not support "
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+ "disabling interrupts: unable to bind.\n");
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+ err = -ENODEV;
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+ goto err;
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+ }
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+ /* Now restore the original value. */
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+ pci_write_config_word(pdev, PCI_COMMAND, orig);
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+err:
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+ pci_unblock_user_cfg_access(pdev);
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+ return err;
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+}
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+
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+static int __devinit 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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+
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+ if (!pdev->irq) {
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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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+ return -ENODEV;
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+ }
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+
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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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+
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+ err = verify_pci_2_3(pdev);
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+ if (err)
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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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+
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+ gdev->info.name = "uio_pci_generic";
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+ gdev->info.version = DRIVER_VERSION;
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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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+ gdev->pdev = pdev;
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+ spin_lock_init(&gdev->lock);
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+
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+ if (uio_register_device(&pdev->dev, &gdev->info))
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+ goto err_register;
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+ pci_set_drvdata(pdev, gdev);
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+
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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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+
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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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+
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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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+
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+static struct pci_driver 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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+
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+static int __init init(void)
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+{
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+ pr_info(DRIVER_DESC " version: " DRIVER_VERSION "\n");
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+ return pci_register_driver(&driver);
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+}
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+
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+static void __exit cleanup(void)
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+{
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+ pci_unregister_driver(&driver);
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+}
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+
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+module_init(init);
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+module_exit(cleanup);
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+
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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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Michael S. Tsirkin