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

[Cam Macdonell <cam@cs.ualberta.ca>]

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 <hjk@linutronix.de>
+ *
+ * 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