[Qemu-devel] [PATCH v6] Shared memory uio_pci driver

[Cam Macdonell]

This patch adds a driver for my shared memory PCI device using the uio_pci
interface.  The driver has three memory regions.  The first memory region is for
device registers for sending interrupts. The second BAR is for receiving MSI-X
interrupts and the third memory region maps the shared memory.  The device only
exports the first and third memory regions to userspace.

This driver supports MSI-X and regular pin interrupts.  Currently, the number
of MSI vectors is set to 1 but it could easily be increased.  If MSI is not
available, then regular interrupts will be used.
---
 drivers/uio/Kconfig       |    8 ++
 drivers/uio/Makefile      |    1 +
 drivers/uio/uio_ivshmem.c |  252 +++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 261 insertions(+), 0 deletions(-)
 create mode 100644 drivers/uio/uio_ivshmem.c

diff --git a/drivers/uio/Kconfig b/drivers/uio/Kconfig
index 1da73ec..b92cded 100644
--- a/drivers/uio/Kconfig
+++ b/drivers/uio/Kconfig
@@ -74,6 +74,14 @@ config UIO_SERCOS3
 
          If you compile this as a module, it will be called uio_sercos3.
 
+config UIO_IVSHMEM
+       tristate "KVM shared memory PCI driver"
+       default n
+       help
+         Userspace I/O interface for the KVM shared memory device.  This
+         driver will make available two memory regions, the first is
+         registers and the second is a region for sharing between VMs.
+
 config UIO_PCI_GENERIC
        tristate "Generic driver for PCI 2.3 and PCI Express cards"
        depends on PCI
diff --git a/drivers/uio/Makefile b/drivers/uio/Makefile
index 18fd818..25c1ca5 100644
--- a/drivers/uio/Makefile
+++ b/drivers/uio/Makefile
@@ -6,3 +6,4 @@ obj-$(CONFIG_UIO_AEC)   += uio_aec.o
 obj-$(CONFIG_UIO_SERCOS3)      += uio_sercos3.o
 obj-$(CONFIG_UIO_PCI_GENERIC)  += uio_pci_generic.o
 obj-$(CONFIG_UIO_NETX) += uio_netx.o
+obj-$(CONFIG_UIO_IVSHMEM) += uio_ivshmem.o
diff --git a/drivers/uio/uio_ivshmem.c b/drivers/uio/uio_ivshmem.c
new file mode 100644
index 0000000..95be1e0
--- /dev/null
+++ b/drivers/uio/uio_ivshmem.c
@@ -0,0 +1,252 @@
+/*
+ * UIO IVShmem Driver
+ *
+ * (C) 2009 Cam Macdonell
+ * based on Hilscher CIF card driver (C) 2007 Hans J. Koch <address@hidden>
+ *
+ * Licensed under GPL version 2 only.
+ *
+ */
+
+#include <linux/device.h>
+#include <linux/module.h>
+#include <linux/pci.h>
+#include <linux/uio_driver.h>
+
+#include <asm/io.h>
+
+#define IntrStatus 0x04
+#define IntrMask 0x00
+
+struct ivshmem_info {
+       struct uio_info *uio;
+       struct pci_dev *dev;
+       char (*msix_names)[256];
+       struct msix_entry *msix_entries;
+       int nvectors;
+};
+
+static irqreturn_t ivshmem_handler(int irq, struct uio_info *dev_info)
+{
+
+       void __iomem *plx_intscr = dev_info->mem[0].internal_addr
+                                       + IntrStatus;
+       u32 val;
+
+       val = readl(plx_intscr);
+       if (val == 0)
+               return IRQ_NONE;
+
+       return IRQ_HANDLED;
+}
+
+static irqreturn_t ivshmem_msix_handler(int irq, void *opaque)
+{
+
+       struct uio_info * dev_info = (struct uio_info *) opaque;
+
+       /* we have to do this explicitly when using MSI-X */
+       uio_event_notify(dev_info);
+       return IRQ_HANDLED;
+}
+
+static void free_msix_vectors(struct ivshmem_info *ivs_info,
+                                                       const int max_vector)
+{
+       int i;
+
+       for (i = 0; i < max_vector; i++)
+               free_irq(ivs_info->msix_entries[i].vector, ivs_info->uio);
+}
+
+static int request_msix_vectors(struct ivshmem_info *ivs_info, int nvectors)
+{
+       int i, err;
+       const char *name = "ivshmem";
+
+       ivs_info->nvectors = nvectors;
+
+       ivs_info->msix_entries = kmalloc(nvectors * sizeof *
+                                               ivs_info->msix_entries,
+                                               GFP_KERNEL);
+       if (ivs_info->msix_entries == NULL)
+               return -ENOSPC;
+
+       ivs_info->msix_names = kmalloc(nvectors * sizeof *ivs_info->msix_names,
+                       GFP_KERNEL);
+       if (ivs_info->msix_names == NULL) {
+               kfree(ivs_info->msix_entries);
+               return -ENOSPC;
+       }
+
+       for (i = 0; i < nvectors; ++i)
+               ivs_info->msix_entries[i].entry = i;
+
+       err = pci_enable_msix(ivs_info->dev, ivs_info->msix_entries,
+                                       ivs_info->nvectors);
+       if (err > 0) {
+               ivs_info->nvectors = err; /* msi-x positive error code
+                                        returns the number available*/
+               err = pci_enable_msix(ivs_info->dev, ivs_info->msix_entries,
+                                       ivs_info->nvectors);
+               if (err) {
+                       printk(KERN_INFO "no MSI (%d). Back to INTx.\n", err);
+                       goto error;
+               }
+       }
+
+       if (err)
+           goto error;
+
+       for (i = 0; i < ivs_info->nvectors; i++) {
+
+               snprintf(ivs_info->msix_names[i], sizeof *ivs_info->msix_names,
+                       "%s-config", name);
+
+               err = request_irq(ivs_info->msix_entries[i].vector,
+                       ivshmem_msix_handler, 0,
+                       ivs_info->msix_names[i], ivs_info->uio);
+
+               if (err) {
+                       free_msix_vectors(ivs_info, i - 1);
+                       goto error;
+               }
+
+       }
+
+       return 0;
+error:
+       kfree(ivs_info->msix_entries);
+       kfree(ivs_info->msix_names);
+       return err;
+
+}
+
+static int __devinit ivshmem_pci_probe(struct pci_dev *dev,
+                                       const struct pci_device_id *id)
+{
+       struct uio_info *info;
+       struct ivshmem_info * ivshmem_info;
+       int nvectors = 1;
+
+       info = kzalloc(sizeof(struct uio_info), GFP_KERNEL);
+       if (!info)
+               return -ENOMEM;
+
+       ivshmem_info = kzalloc(sizeof(struct ivshmem_info), GFP_KERNEL);
+       if (!ivshmem_info) {
+               kfree(info);
+               return -ENOMEM;
+       }
+
+       if (pci_enable_device(dev))
+               goto out_free;
+
+       if (pci_request_regions(dev, "ivshmem"))
+               goto out_disable;
+
+       info->mem[0].addr = pci_resource_start(dev, 0);
+       if (!info->mem[0].addr)
+               goto out_release;
+
+       info->mem[0].size = pci_resource_len(dev, 0);
+       info->mem[0].internal_addr = pci_ioremap_bar(dev, 0);
+       if (!info->mem[0].internal_addr) {
+               goto out_release;
+       }
+
+       info->mem[0].memtype = UIO_MEM_PHYS;
+
+       info->mem[1].addr = pci_resource_start(dev, 2);
+       if (!info->mem[1].addr)
+               goto out_unmap;
+       info->mem[1].internal_addr = pci_ioremap_bar(dev, 2);
+       if (!info->mem[1].internal_addr)
+               goto out_unmap;
+
+       info->mem[1].size = pci_resource_len(dev, 2);
+       info->mem[1].memtype = UIO_MEM_PHYS;
+
+       ivshmem_info->uio = info;
+       ivshmem_info->dev = dev;
+
+       if (request_msix_vectors(ivshmem_info, nvectors) != 0) {
+               printk(KERN_INFO "regular IRQs\n");
+               info->irq = dev->irq;
+               info->irq_flags = IRQF_SHARED;
+               info->handler = ivshmem_handler;
+               writel(0xffffffff, info->mem[0].internal_addr + IntrMask);
+       } else {
+               printk(KERN_INFO "MSI-X enabled\n");
+               info->irq = -1;
+       }
+
+       info->name = "ivshmem";
+       info->version = "0.0.1";
+
+       if (uio_register_device(&dev->dev, info))
+               goto out_unmap2;
+
+       pci_set_drvdata(dev, info);
+
+
+       return 0;
+out_unmap2:
+       iounmap(info->mem[2].internal_addr);
+out_unmap:
+       iounmap(info->mem[0].internal_addr);
+out_release:
+       pci_release_regions(dev);
+out_disable:
+       pci_disable_device(dev);
+out_free:
+       kfree (info);
+       return -ENODEV;
+}
+
+static void ivshmem_pci_remove(struct pci_dev *dev)
+{
+       struct uio_info *info = pci_get_drvdata(dev);
+
+       uio_unregister_device(info);
+       pci_release_regions(dev);
+       pci_disable_device(dev);
+       pci_set_drvdata(dev, NULL);
+       iounmap(info->mem[0].internal_addr);
+
+       kfree (info);
+}
+
+static struct pci_device_id ivshmem_pci_ids[] __devinitdata = {
+       {
+               .vendor =       0x1af4,
+               .device =       0x1110,
+               .subvendor =    PCI_ANY_ID,
+               .subdevice =    PCI_ANY_ID,
+       },
+       { 0, }
+};
+
+static struct pci_driver ivshmem_pci_driver = {
+       .name = "uio_ivshmem",
+       .id_table = ivshmem_pci_ids,
+       .probe = ivshmem_pci_probe,
+       .remove = ivshmem_pci_remove,
+};
+
+static int __init ivshmem_init_module(void)
+{
+       return pci_register_driver(&ivshmem_pci_driver);
+}
+
+static void __exit ivshmem_exit_module(void)
+{
+       pci_unregister_driver(&ivshmem_pci_driver);
+}
+
+module_init(ivshmem_init_module);
+module_exit(ivshmem_exit_module);
+
+MODULE_DEVICE_TABLE(pci, ivshmem_pci_ids);
+MODULE_LICENSE("GPL v2");
+MODULE_AUTHOR("Cam Macdonell");
-- 
1.6.3.2.198.g6096d