virtio: Small refactor for virtio con

refactor the interfaces between different virtio console
layers for a better OO design.

Signed-off-by: Jingyao Zhou <[email protected]>

libsel4vmmplatsupport/include/sel4vmmplatsupport/drivers/virtio_con.h

@@ -21,15 +21,17 @@
 /***
  * @struct virtio_con
  * Virtio Console Driver Interface
- * @param {unsigned int} iobase                             IO Port base for virtio con device
- * @param {virtio_emul_t *} emul                            Virtio console emulation interface: VMM <-> Guest
- * @param {struct console_passthrough} emul_driver_funcs    Virtio console emulation functions: VMM <-> Guest
- * @param {ps_io_ops_t} ioops                               Platform support io ops datastructure
+ * @param {unsigned int} iobase                                 IO Port base for virtio con device
+ * @param {virtio_emul_t *} emul                                Virtio console emulation interface: VMM <-> Guest
+ * @param {struct eth_driver *} emul_driver                     Backend console driver interface: VMM <-> console driver
+ * @param {struct virtio_console_passthrough} emul_driver_funcs Virtio console emulation functions: VMM <-> Guest
+ * @param {ps_io_ops_t} ioops                                   Platform support io ops datastructure
  */
 typedef struct virtio_con {
     unsigned int iobase;
     virtio_emul_t *emul;
-    struct console_passthrough emul_driver_funcs;
+    struct virtio_console_driver *emul_driver;
+    struct virtio_console_passthrough emul_driver_funcs;
     ps_io_ops_t ioops;
 } virtio_con_t;
 
@@ -55,4 +57,4 @@ virtio_con_t *common_make_virtio_con(vm_t *vm,
                                      ioport_type_t port_type,
                                      unsigned int interrupt_pin,
                                      unsigned int interrupt_line,
-                                     struct console_passthrough backend);
+                                     struct virtio_console_passthrough backend);

libsel4vmmplatsupport/include/sel4vmmplatsupport/drivers/virtio_pci_console.h

@@ -6,13 +6,44 @@
 
 #pragma once
 
-typedef void (*console_handle_irq_fn_t)(void *cookie);
+typedef struct virtio_emul virtio_emul_t;
+
 typedef void (*console_putchar_fn_t)(int port, char c);
 
-struct console_passthrough {
-    console_handle_irq_fn_t handleIRQ;
-    console_putchar_fn_t    putchar;
-    void                   *console_data;
+/***
+ * @struct virtio_console_callbacks
+ * Callback functions provided by the emul layer of virtio console
+ *
+ * @param backend_putchar putchar
+ */
+typedef struct virtio_console_callbacks {
+    void (*emul_putchar)(int port, virtio_emul_t *con, char *buffer, uint32_t head, uint32_t tail);
+} virtio_console_callbacks_t;
+
+/***
+ * @struct virtio_console_passthrough
+ * Virtion console backend layer interface
+ *
+ * @param handleIRQ handle IRQ
+ * @param backend_putchar putchar
+ * @param console_data data specified by the backend
+ */
+typedef struct virtio_console_passthrough {
+    void (*handleIRQ)(void *cookie);
+    console_putchar_fn_t backend_putchar;
+    void *console_data;
+} virtio_console_passthrough_t;
+
+/***
+ * @struct virtio_console_driver
+ * Structure to hold the interface for a virtio console driver
+ *
+ * @param backend_fn backend layer interface
+ * @param emul_cb emul layer interface
+ */
+struct virtio_console_driver {
+    virtio_console_passthrough_t backend_fn;
+    virtio_console_callbacks_t emul_cb;
 };
 
-typedef int (*console_driver_init)(struct console_passthrough *driver, ps_io_ops_t io_ops, void *config);
+typedef int (*console_driver_init)(struct virtio_console_driver *driver, ps_io_ops_t io_ops, void *config);

libsel4vmmplatsupport/src/drivers/virtio_con.c

@@ -42,10 +42,11 @@ static int virtio_con_io_out(void *cookie, unsigned int port_no, unsigned int si
     return 0;
 }
 
-static int emul_con_driver_init(struct console_passthrough *driver, ps_io_ops_t io_ops, void *config)
+static int emul_con_driver_init(struct virtio_console_driver *driver, ps_io_ops_t io_ops, void *config)
 {
     virtio_con_t *con = (virtio_con_t *)config;
-    *driver = con->emul_driver_funcs;
+    driver->backend_fn = con->emul_driver_funcs;
+    con->emul_driver = driver;
     return 0;
 }
 
@@ -88,7 +89,7 @@ static vmm_pci_entry_t vmm_virtio_console_pci_bar(unsigned int iobase,
 
 virtio_con_t *common_make_virtio_con(vm_t *vm, vmm_pci_space_t *pci, vmm_io_port_list_t *ioport,
                                      ioport_range_t ioport_range, ioport_type_t port_type, unsigned int interrupt_pin, unsigned int interrupt_line,
-                                     struct console_passthrough backend)
+                                     struct virtio_console_passthrough backend)
 {
     int err = ps_new_stdlib_malloc_ops(&ops.malloc_ops);
     ZF_LOGF_IF(err, "Failed to get malloc ops");

libsel4vmmplatsupport/src/drivers/virtio_console_emul.c

@@ -17,7 +17,7 @@
 static char buf[VUART_BUFLEN];
 
 typedef struct console_virtio_emul_internal {
-    struct console_passthrough driver;
+    struct virtio_console_driver driver;
     /* counter for console ports */
     unsigned int con_count;
     /* what queue did data come through? */
@@ -96,7 +96,7 @@ static void emul_con_rx_complete(virtio_emul_t *emul, int queue, char *buf, uint
         /* record that we've used this descriptor chain now */
         virtq->last_idx[queue]++;
         /* notify the guest that there is something in its used ring */
-        con->driver.handleIRQ(con->driver.console_data);
+        con->driver.backend_fn.handleIRQ(con->driver.backend_fn.console_data);
     }
 }
 
@@ -120,6 +120,10 @@ void virtio_console_putchar(int port, virtio_emul_t *emul, char *buffer, uint32_
     emul_con_rx_complete(emul, vq_num, buffer, head, tail);
 }
 
+static virtio_console_callbacks_t emul_callbacks = {
+    .emul_putchar = virtio_console_putchar
+};
+
 /* Write to port attached to queue number */
 static void port_write(virtio_emul_t *emul, int queue, char *buffer, unsigned int len)
 {
@@ -134,7 +138,7 @@ static void port_write(virtio_emul_t *emul, int queue, char *buffer, unsigned in
 
     /* forward it */
     for (int i = 0; i < len; i++) {
-        con->driver.putchar(port, buffer[i]);
+        con->driver.backend_fn.backend_putchar(port, buffer[i]);
     }
 }
 
@@ -232,7 +236,7 @@ static void emul_con_notify_tx(virtio_emul_t *emul)
         idx++;
         struct vring_used_elem used_elem = {desc_head, 0};
         ring_used_add(emul, &virtq->vring[con->queue_num], used_elem);
-        con->driver.handleIRQ(con->driver.console_data);
+        con->driver.backend_fn.handleIRQ(con->driver.backend_fn.console_data);
     }
     /* update which parts of the ring we have processed */
     virtq->last_idx[con->queue_num] = idx;
@@ -299,16 +303,18 @@ void *console_virtio_emul_init(virtio_emul_t *emul, ps_io_ops_t io_ops, console_
         goto error;
     }
 
+    emul->device_io_in = console_device_emul_io_in;
+    emul->device_io_out = console_device_emul_io_out;
+    emul->notify = emul_con_notify_tx;
+    internal->con_count = 0;
+    internal->driver.emul_cb = emul_callbacks;
+
     err = driver(&internal->driver, io_ops, config);
     if (err) {
         ZF_LOGE("Failed to initialize driver");
         goto error;
     }
 
-    emul->device_io_in = console_device_emul_io_in;
-    emul->device_io_out = console_device_emul_io_out;
-    emul->notify = emul_con_notify_tx;
-    internal->con_count = 0;
     return (void *)internal;
 error:
     if (emul) {