virtio-mmio: Devices parameter parsing

This patch adds an option to instantiate guest virtio-mmio devices
basing on a kernel command line (or module) parameter, for example:

	virtio_mmio.devices=0x100@0x100b0000:48

Signed-off-by: Pawel Moll <pawel.moll@arm.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index c1601e5..8b35051 100644 (file)
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -110,6 +110,7 @@ parameter is applicable:
        USB     USB support is enabled.
        USBHID  USB Human Interface Device support is enabled.
        V4L     Video For Linux support is enabled.
+       VMMIO   Driver for memory mapped virtio devices is enabled.
        VGA     The VGA console has been enabled.
        VT      Virtual terminal support is enabled.
        WDT     Watchdog support is enabled.
@@ -2847,6 +2848,22 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
        video=          [FB] Frame buffer configuration
                        See Documentation/fb/modedb.txt.
 
+       virtio_mmio.device=
+                       [VMMIO] Memory mapped virtio (platform) device.
+
+                               <size>@<baseaddr>:<irq>[:<id>]
+                       where:
+                               <size>     := size (can use standard suffixes
+                                               like K, M and G)
+                               <baseaddr> := physical base address
+                               <irq>      := interrupt number (as passed to
+                                               request_irq())
+                               <id>       := (optional) platform device id
+                       example:
+                               virtio_mmio.device=1K@0x100b0000:48:7
+
+                       Can be used multiple times for multiple devices.
+
        vga=            [BOOT,X86-32] Select a particular video mode
                        See Documentation/x86/boot.txt and
                        Documentation/svga.txt.

diff --git a/drivers/virtio/Kconfig b/drivers/virtio/Kconfig
index 1a61939..f38b17a 100644 (file)
--- a/drivers/virtio/Kconfig
+++ b/drivers/virtio/Kconfig
@@ -46,4 +46,15 @@ config VIRTIO_BALLOON
 
         If unsure, say N.
 
+config VIRTIO_MMIO_CMDLINE_DEVICES
+       bool "Memory mapped virtio devices parameter parsing"
+       depends on VIRTIO_MMIO
+       ---help---
+        Allow virtio-mmio devices instantiation via the kernel command line
+        or module parameters. Be aware that using incorrect parameters (base
+        address in particular) can crash your system - you have been warned.
+        See Documentation/kernel-parameters.txt for details.
+
+        If unsure, say 'N'.
+
 endmenu

diff --git a/drivers/virtio/virtio_mmio.c b/drivers/virtio/virtio_mmio.c
index 01d6dc2..453db0c 100644 (file)
--- a/drivers/virtio/virtio_mmio.c
+++ b/drivers/virtio/virtio_mmio.c
@@ -6,6 +6,50 @@
  * This module allows virtio devices to be used over a virtual, memory mapped
  * platform device.
  *
+ * The guest device(s) may be instantiated in one of three equivalent ways:
+ *
+ * 1. Static platform device in board's code, eg.:
+ *
+ *     static struct platform_device v2m_virtio_device = {
+ *             .name = "virtio-mmio",
+ *             .id = -1,
+ *             .num_resources = 2,
+ *             .resource = (struct resource []) {
+ *                     {
+ *                             .start = 0x1001e000,
+ *                             .end = 0x1001e0ff,
+ *                             .flags = IORESOURCE_MEM,
+ *                     }, {
+ *                             .start = 42 + 32,
+ *                             .end = 42 + 32,
+ *                             .flags = IORESOURCE_IRQ,
+ *                     },
+ *             }
+ *     };
+ *
+ * 2. Device Tree node, eg.:
+ *
+ *             virtio_block@1e000 {
+ *                     compatible = "virtio,mmio";
+ *                     reg = <0x1e000 0x100>;
+ *                     interrupts = <42>;
+ *             }
+ *
+ * 3. Kernel module (or command line) parameter. Can be used more than once -
+ *    one device will be created for each one. Syntax:
+ *
+ *             [virtio_mmio.]device=<size>@<baseaddr>:<irq>[:<id>]
+ *    where:
+ *             <size>     := size (can use standard suffixes like K, M or G)
+ *             <baseaddr> := physical base address
+ *             <irq>      := interrupt number (as passed to request_irq())
+ *             <id>       := (optional) platform device id
+ *    eg.:
+ *             virtio_mmio.device=0x100@0x100b0000:48 \
+ *                             virtio_mmio.device=1K@0x1001e000:74
+ *
+ *
+ *
  * Registers layout (all 32-bit wide):
  *
  * offset d. name             description
@@ -42,6 +86,8 @@
  * See the COPYING file in the top-level directory.
  */
 
+#define pr_fmt(fmt) "virtio-mmio: " fmt
+
 #include <linux/highmem.h>
 #include <linux/interrupt.h>
 #include <linux/io.h>
@@ -449,6 +495,122 @@ static int __devexit virtio_mmio_remove(struct platform_device *pdev)
 
 
 
+/* Devices list parameter */
+
+#if defined(CONFIG_VIRTIO_MMIO_CMDLINE_DEVICES)
+
+static struct device vm_cmdline_parent = {
+       .init_name = "virtio-mmio-cmdline",
+};
+
+static int vm_cmdline_parent_registered;
+static int vm_cmdline_id;
+
+static int vm_cmdline_set(const char *device,
+               const struct kernel_param *kp)
+{
+       int err;
+       struct resource resources[2] = {};
+       char *str;
+       long long int base;
+       int processed, consumed = 0;
+       struct platform_device *pdev;
+
+       resources[0].flags = IORESOURCE_MEM;
+       resources[1].flags = IORESOURCE_IRQ;
+
+       resources[0].end = memparse(device, &str) - 1;
+
+       processed = sscanf(str, "@%lli:%u%n:%d%n",
+                       &base, &resources[1].start, &consumed,
+                       &vm_cmdline_id, &consumed);
+
+       if (processed < 2 || processed > 3 || str[consumed])
+               return -EINVAL;
+
+       resources[0].start = base;
+       resources[0].end += base;
+       resources[1].end = resources[1].start;
+
+       if (!vm_cmdline_parent_registered) {
+               err = device_register(&vm_cmdline_parent);
+               if (err) {
+                       pr_err("Failed to register parent device!\n");
+                       return err;
+               }
+               vm_cmdline_parent_registered = 1;
+       }
+
+       pr_info("Registering device virtio-mmio.%d at 0x%llx-0x%llx, IRQ %d.\n",
+                      vm_cmdline_id,
+                      (unsigned long long)resources[0].start,
+                      (unsigned long long)resources[0].end,
+                      (int)resources[1].start);
+
+       pdev = platform_device_register_resndata(&vm_cmdline_parent,
+                       "virtio-mmio", vm_cmdline_id++,
+                       resources, ARRAY_SIZE(resources), NULL, 0);
+       if (IS_ERR(pdev))
+               return PTR_ERR(pdev);
+
+       return 0;
+}
+
+static int vm_cmdline_get_device(struct device *dev, void *data)
+{
+       char *buffer = data;
+       unsigned int len = strlen(buffer);
+       struct platform_device *pdev = to_platform_device(dev);
+
+       snprintf(buffer + len, PAGE_SIZE - len, "0x%llx@0x%llx:%llu:%d\n",
+                       pdev->resource[0].end - pdev->resource[0].start + 1ULL,
+                       (unsigned long long)pdev->resource[0].start,
+                       (unsigned long long)pdev->resource[1].start,
+                       pdev->id);
+       return 0;
+}
+
+static int vm_cmdline_get(char *buffer, const struct kernel_param *kp)
+{
+       buffer[0] = '\0';
+       device_for_each_child(&vm_cmdline_parent, buffer,
+                       vm_cmdline_get_device);
+       return strlen(buffer) + 1;
+}
+
+static struct kernel_param_ops vm_cmdline_param_ops = {
+       .set = vm_cmdline_set,
+       .get = vm_cmdline_get,
+};
+
+device_param_cb(device, &vm_cmdline_param_ops, NULL, S_IRUSR);
+
+static int vm_unregister_cmdline_device(struct device *dev,
+               void *data)
+{
+       platform_device_unregister(to_platform_device(dev));
+
+       return 0;
+}
+
+static void vm_unregister_cmdline_devices(void)
+{
+       if (vm_cmdline_parent_registered) {
+               device_for_each_child(&vm_cmdline_parent, NULL,
+                               vm_unregister_cmdline_device);
+               device_unregister(&vm_cmdline_parent);
+               vm_cmdline_parent_registered = 0;
+       }
+}
+
+#else
+
+static void vm_unregister_cmdline_devices(void)
+{
+}
+
+#endif
+
 /* Platform driver */
 
 static struct of_device_id virtio_mmio_match[] = {
@@ -475,6 +637,7 @@ static int __init virtio_mmio_init(void)
 static void __exit virtio_mmio_exit(void)
 {
        platform_driver_unregister(&virtio_mmio_driver);
+       vm_unregister_cmdline_devices();
 }
 
 module_init(virtio_mmio_init);