USB devices may have very limited endpoint packet sizes, so that
notifications can not be transferred within one single usb packet.
Reassembling of multiple packages may be necessary.
Signed-off-by: Tobias Herzog <t-herzog@xxxxxx>
---
drivers/usb/class/cdc-acm.c | 112 ++++++++++++++++++++++++++++++++------------
drivers/usb/class/cdc-acm.h | 3 ++
2 files changed, 86 insertions(+), 29 deletions(-)
diff --git a/drivers/usb/class/cdc-acm.c b/drivers/usb/class/cdc-acm.c
index f554e2f..58efa15 100644
--- a/drivers/usb/class/cdc-acm.c
+++ b/drivers/usb/class/cdc-acm.c
@@ -35,6 +35,7 @@
#include <linux/errno.h>
#include <linux/init.h>
#include <linux/slab.h>
+#include <linux/log2.h>
#include <linux/tty.h>
#include <linux/serial.h>
#include <linux/tty_driver.h>
@@ -282,39 +283,13 @@ static DEVICE_ATTR(iCountryCodeRelDate, S_IRUGO, show_country_rel_date, NULL);
* Interrupt handlers for various ACM device responses
*/
-/* control interface reports status changes with "interrupt" transfers */
-static void acm_ctrl_irq(struct urb *urb)
+static void acm_process_notification(struct acm *acm, unsigned char *buf)
{
- struct acm *acm = urb->context;
- struct usb_cdc_notification *dr = urb->transfer_buffer;
- unsigned char *data;
int newctrl;
int difference;
- int retval;
- int status = urb->status;
-
- switch (status) {
- case 0:
- /* success */
- break;
- case -ECONNRESET:
- case -ENOENT:
- case -ESHUTDOWN:
- /* this urb is terminated, clean up */
- dev_dbg(&acm->control->dev,
- "%s - urb shutting down with status: %d\n",
- __func__, status);
- return;
- default:
- dev_dbg(&acm->control->dev,
- "%s - nonzero urb status received: %d\n",
- __func__, status);
- goto exit;
- }
+ struct usb_cdc_notification *dr = (struct usb_cdc_notification *)buf;
+ unsigned char *data = buf + sizeof(struct usb_cdc_notification);
- usb_mark_last_busy(acm->dev);
-
- data = (unsigned char *)(dr + 1);
switch (dr->bNotificationType) {
case USB_CDC_NOTIFY_NETWORK_CONNECTION:
dev_dbg(&acm->control->dev,
@@ -367,9 +342,83 @@ static void acm_ctrl_irq(struct urb *urb)
"%s - unknown notification %d received: index %d len %d\n",
__func__,
dr->bNotificationType, dr->wIndex, dr->wLength);
+ }
+}
+/* control interface reports status changes with "interrupt" transfers */
+static void acm_ctrl_irq(struct urb *urb)
+{
+ struct acm *acm = urb->context;
+ struct usb_cdc_notification *dr = urb->transfer_buffer;
+ unsigned int current_size = urb->actual_length;
+ unsigned int expected_size, copy_size, alloc_size;
+ int retval;
+ int status = urb->status;
+
+ switch (status) {
+ case 0:
+ /* success */
break;
+ case -ECONNRESET:
+ case -ENOENT:
+ case -ESHUTDOWN:
+ /* this urb is terminated, clean up */
+ acm->nb_index = 0;
+ dev_dbg(&acm->control->dev,
+ "%s - urb shutting down with status: %d\n",
+ __func__, status);
+ return;
+ default:
+ dev_dbg(&acm->control->dev,
+ "%s - nonzero urb status received: %d\n",
+ __func__, status);
+ goto exit;
+ }
+
+ usb_mark_last_busy(acm->dev);
+
+ if (acm->nb_index)
+ dr = (struct usb_cdc_notification *)acm->notification_buffer;
+
+ /* size = notification-header + (optional) data */
+ expected_size = sizeof(struct usb_cdc_notification) +
+ le16_to_cpu(dr->wLength);
+
+ if (current_size < expected_size) {
+ /* notification is transmitted fragmented, reassemble */
+ if (acm->nb_size < expected_size) {
+ if (acm->nb_size) {
+ kfree(acm->notification_buffer);
+ acm->nb_size = 0;
+ }
+ alloc_size = roundup_pow_of_two(expected_size);
+ /*
+ * kmalloc ensures a valid notification_buffer after a
+ * use of kfree in case the previous allocation was too
+ * small. Final freeing is done on disconnect.
+ */
+ acm->notification_buffer =
+ kmalloc(alloc_size, GFP_ATOMIC);
+ if (!acm->notification_buffer)
+ goto exit;
+ acm->nb_size = alloc_size;
+ }
+
+ copy_size = min(current_size,
+ expected_size - acm->nb_index);
+
+ memcpy(&acm->notification_buffer[acm->nb_index],
+ urb->transfer_buffer, copy_size);
+ acm->nb_index += copy_size;
+ current_size = acm->nb_index;
}
+
+ if (current_size >= expected_size) {
+ /* notification complete */
+ acm_process_notification(acm, (unsigned char *)dr);
+ acm->nb_index = 0;
+ }
+
exit:
retval = usb_submit_urb(urb, GFP_ATOMIC);
if (retval && retval != -EPERM)
@@ -1493,6 +1542,9 @@ static int acm_probe(struct usb_interface *intf,
epctrl->bInterval ? epctrl->bInterval : 16);
acm->ctrlurb->transfer_flags |= URB_NO_TRANSFER_DMA_MAP;
acm->ctrlurb->transfer_dma = acm->ctrl_dma;
+ acm->notification_buffer = NULL;
+ acm->nb_index = 0;
+ acm->nb_size = 0;
dev_info(&intf->dev, "ttyACM%d: USB ACM device\n", minor);
@@ -1585,6 +1637,8 @@ static void acm_disconnect(struct usb_interface *intf)
usb_free_coherent(acm->dev, acm->ctrlsize, acm->ctrl_buffer, acm->ctrl_dma);
acm_read_buffers_free(acm);
+ kfree(acm->notification_buffer);
+
if (!acm->combined_interfaces)
usb_driver_release_interface(&acm_driver, intf == acm->control ?
acm->data : acm->control);
diff --git a/drivers/usb/class/cdc-acm.h b/drivers/usb/class/cdc-acm.h
index c980f11..b519138 100644
--- a/drivers/usb/class/cdc-acm.h
+++ b/drivers/usb/class/cdc-acm.h
@@ -98,6 +98,9 @@ struct acm {
struct acm_wb *putbuffer; /* for acm_tty_put_char() */
int rx_buflimit;
spinlock_t read_lock;
+ u8 *notification_buffer; /* to reassemble fragmented notifications */
+ unsigned int nb_index;
+ unsigned int nb_size;
int write_used; /* number of non-empty write buffers */
int transmitting;
spinlock_t write_lock;
--
2.1.4