To identify which port data that gets sent to the Host belongs to, we'll
have to add a 'header' to each outgoing buffer that will tell the Host
the port number.
This is also done for each buffer that's received from userspace.
The header is currently a 0-length field, but will contain the port id
among other things when support for multiple ports per device is added.
Signed-off-by: Amit Shah <amit.shah@xxxxxxxxxx>
---
drivers/char/virtio_console.c | 37 +++++++++++++++++++++++++++++++------
include/linux/virtio_console.h | 7 +++++++
2 files changed, 38 insertions(+), 6 deletions(-)
diff --git a/drivers/char/virtio_console.c b/drivers/char/virtio_console.c
index 64a927c..def1678 100644
--- a/drivers/char/virtio_console.c
+++ b/drivers/char/virtio_console.c
@@ -150,24 +150,39 @@ out:
return port;
}
+static inline bool use_multiport(struct ports_device *portdev)
+{
+ /*
+ * This condition can be true when put_chars is called from
+ * early_init
+ */
+ if (!portdev->vdev)
+ return 0;
+ /* Check for feature bit once multiport support has been added */
+ return 0;
+}
+
static ssize_t send_buf(struct port *port, const char *in_buf, size_t in_count)
{
struct scatterlist sg[1];
+ struct virtio_console_header header;
struct virtqueue *out_vq;
struct port_buffer *buf;
size_t in_offset, copy_size;
ssize_t ret;
unsigned long irqf;
+ unsigned int header_len;
if (!in_count)
return 0;
out_vq = port->portdev->out_vq;
+ header_len = use_multiport(port->portdev) ? sizeof(header) : 0;
in_offset = 0; /* offset in the user buffer */
spin_lock_irqsave(&port->portdev->write_list_lock, irqf);
while (in_count - in_offset) {
- copy_size = min(in_count - in_offset, PAGE_SIZE);
+ copy_size = min(in_count - in_offset + header_len, PAGE_SIZE);
if (list_empty(&port->portdev->unused_write_head))
break;
@@ -177,15 +192,19 @@ static ssize_t send_buf(struct port *port, const char *in_buf, size_t in_count)
list_del(&buf->list);
spin_unlock_irqrestore(&port->portdev->write_list_lock, irqf);
+ if (header_len) {
+ memcpy(buf->buf, &header, header_len);
+ copy_size -= header_len;
+ }
/*
* Since we're not sure when the host will actually
* consume the data and tell us about it, we have
* to copy the data here in case the caller
* frees the in_buf
*/
- memcpy(buf->buf, in_buf + in_offset, copy_size);
+ memcpy(buf->buf + header_len, in_buf + in_offset, copy_size);
- buf->len = copy_size;
+ buf->len = header_len + copy_size;
sg_init_one(sg, buf->buf, buf->len);
spin_lock_irqsave(&port->portdev->write_list_lock, irqf);
@@ -196,7 +215,7 @@ static ssize_t send_buf(struct port *port, const char *in_buf, size_t in_count)
&port->portdev->unused_write_head);
break;
}
- in_offset += buf->len;
+ in_offset += buf->len - header_len;
/* No space left in the vq anyway */
if (!ret)
@@ -494,19 +513,25 @@ static void *get_incoming_buf(struct ports_device *portdev,
static void rx_work_handler(struct work_struct *work)
{
+ struct virtio_console_header header;
struct ports_device *portdev;
struct port *port;
struct port_buffer *buf;
- unsigned int tmplen;
+ unsigned int tmplen, header_len;
bool console_activity = false;
portdev = container_of(work, struct ports_device, rx_work);
+ header_len = use_multiport(portdev) ? sizeof(header) : 0;
/* We currently have only one port */
port = find_port_by_vtermno(0);
while ((buf = get_incoming_buf(portdev, &tmplen))) {
+
+ if (use_multiport(portdev))
+ memcpy(&header, buf->buf, header_len);
+
buf->len = tmplen;
- buf->offset = 0;
+ buf->offset = header_len;
spin_lock_irq(&port->readbuf_list_lock);
list_add_tail(&buf->list, &port->readbuf_head);
diff --git a/include/linux/virtio_console.h b/include/linux/virtio_console.h
index 9e0da40..3dfc7d1 100644
--- a/include/linux/virtio_console.h
+++ b/include/linux/virtio_console.h
@@ -18,6 +18,13 @@ struct virtio_console_config {
__u16 rows;
} __attribute__((packed));
+/*
+ * This struct is put at the start of each buffer that gets passed to
+ * Host and vice-versa.
+ */
+struct virtio_console_header {
+ /* Empty till multiport support is added */
+} __attribute__((packed));
#ifdef __KERNEL__
int __init virtio_cons_early_init(int (*put_chars)(u32, const char *, int));
--
1.6.2.5
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