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path: root/drivers/usb/class/cdc-acm.c
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Diffstat (limited to 'drivers/usb/class/cdc-acm.c')
-rw-r--r--drivers/usb/class/cdc-acm.c209
1 files changed, 175 insertions, 34 deletions
diff --git a/drivers/usb/class/cdc-acm.c b/drivers/usb/class/cdc-acm.c
index 6d1f9b6..69e859e 100644
--- a/drivers/usb/class/cdc-acm.c
+++ b/drivers/usb/class/cdc-acm.c
@@ -106,6 +106,111 @@ static int acm_ctrl_msg(struct acm *acm, int request, int value, void *buf, int
acm_ctrl_msg(acm, USB_CDC_REQ_SEND_BREAK, ms, NULL, 0)
/*
+ * Write buffer management.
+ * All of these assume proper locks taken by the caller.
+ */
+
+static int acm_wb_alloc(struct acm *acm)
+{
+ int i, wbn;
+ struct acm_wb *wb;
+
+ wbn = acm->write_current;
+ i = 0;
+ for (;;) {
+ wb = &acm->wb[wbn];
+ if (!wb->use) {
+ wb->use = 1;
+ return wbn;
+ }
+ wbn = (wbn + 1) % ACM_NWB;
+ if (++i >= ACM_NWB)
+ return -1;
+ }
+}
+
+static void acm_wb_free(struct acm *acm, int wbn)
+{
+ acm->wb[wbn].use = 0;
+}
+
+static int acm_wb_is_avail(struct acm *acm)
+{
+ int i, n;
+
+ n = 0;
+ for (i = 0; i < ACM_NWB; i++) {
+ if (!acm->wb[i].use)
+ n++;
+ }
+ return n;
+}
+
+static inline int acm_wb_is_used(struct acm *acm, int wbn)
+{
+ return acm->wb[wbn].use;
+}
+
+/*
+ * Finish write.
+ */
+static void acm_write_done(struct acm *acm)
+{
+ unsigned long flags;
+ int wbn;
+
+ spin_lock_irqsave(&acm->write_lock, flags);
+ acm->write_ready = 1;
+ wbn = acm->write_current;
+ acm_wb_free(acm, wbn);
+ acm->write_current = (wbn + 1) % ACM_NWB;
+ spin_unlock_irqrestore(&acm->write_lock, flags);
+}
+
+/*
+ * Poke write.
+ */
+static int acm_write_start(struct acm *acm)
+{
+ unsigned long flags;
+ int wbn;
+ struct acm_wb *wb;
+ int rc;
+
+ spin_lock_irqsave(&acm->write_lock, flags);
+ if (!acm->dev) {
+ spin_unlock_irqrestore(&acm->write_lock, flags);
+ return -ENODEV;
+ }
+
+ if (!acm->write_ready) {
+ spin_unlock_irqrestore(&acm->write_lock, flags);
+ return 0; /* A white lie */
+ }
+
+ wbn = acm->write_current;
+ if (!acm_wb_is_used(acm, wbn)) {
+ spin_unlock_irqrestore(&acm->write_lock, flags);
+ return 0;
+ }
+ wb = &acm->wb[wbn];
+
+ acm->write_ready = 0;
+ spin_unlock_irqrestore(&acm->write_lock, flags);
+
+ acm->writeurb->transfer_buffer = wb->buf;
+ acm->writeurb->transfer_dma = wb->dmah;
+ acm->writeurb->transfer_buffer_length = wb->len;
+ acm->writeurb->dev = acm->dev;
+
+ if ((rc = usb_submit_urb(acm->writeurb, GFP_ATOMIC)) < 0) {
+ dbg("usb_submit_urb(write bulk) failed: %d", rc);
+ acm_write_done(acm);
+ }
+ return rc;
+}
+
+/*
* Interrupt handlers for various ACM device responses
*/
@@ -237,17 +342,13 @@ static void acm_rx_tasklet(unsigned long _acm)
static void acm_write_bulk(struct urb *urb, struct pt_regs *regs)
{
struct acm *acm = (struct acm *)urb->context;
- dbg("Entering acm_write_bulk with status %d\n", urb->status);
-
- if (!ACM_READY(acm))
- goto out;
- if (urb->status)
- dbg("nonzero write bulk status received: %d", urb->status);
+ dbg("Entering acm_write_bulk with status %d\n", urb->status);
- schedule_work(&acm->work);
-out:
- acm->ready_for_write = 1;
+ acm_write_done(acm);
+ acm_write_start(acm);
+ if (ACM_READY(acm))
+ schedule_work(&acm->work);
}
static void acm_softint(void *private)
@@ -351,32 +452,33 @@ static int acm_tty_write(struct tty_struct *tty, const unsigned char *buf, int c
{
struct acm *acm = tty->driver_data;
int stat;
+ unsigned long flags;
+ int wbn;
+ struct acm_wb *wb;
+
dbg("Entering acm_tty_write to write %d bytes,\n", count);
if (!ACM_READY(acm))
return -EINVAL;
- if (!acm->ready_for_write)
- return 0;
if (!count)
return 0;
- count = (count > acm->writesize) ? acm->writesize : count;
+ spin_lock_irqsave(&acm->write_lock, flags);
+ if ((wbn = acm_wb_alloc(acm)) < 0) {
+ spin_unlock_irqrestore(&acm->write_lock, flags);
+ acm_write_start(acm);
+ return 0;
+ }
+ wb = &acm->wb[wbn];
+ count = (count > acm->writesize) ? acm->writesize : count;
dbg("Get %d bytes...", count);
- memcpy(acm->write_buffer, buf, count);
- dbg(" Successfully copied.\n");
+ memcpy(wb->buf, buf, count);
+ wb->len = count;
+ spin_unlock_irqrestore(&acm->write_lock, flags);
- acm->writeurb->transfer_buffer_length = count;
- acm->writeurb->dev = acm->dev;
-
- acm->ready_for_write = 0;
- stat = usb_submit_urb(acm->writeurb, GFP_ATOMIC);
- if (stat < 0) {
- dbg("usb_submit_urb(write bulk) failed");
- acm->ready_for_write = 1;
+ if ((stat = acm_write_start(acm)) < 0)
return stat;
- }
-
return count;
}
@@ -385,7 +487,11 @@ static int acm_tty_write_room(struct tty_struct *tty)
struct acm *acm = tty->driver_data;
if (!ACM_READY(acm))
return -EINVAL;
- return !acm->ready_for_write ? 0 : acm->writesize;
+ /*
+ * Do not let the line discipline to know that we have a reserve,
+ * or it might get too enthusiastic.
+ */
+ return (acm->write_ready && acm_wb_is_avail(acm)) ? acm->writesize : 0;
}
static int acm_tty_chars_in_buffer(struct tty_struct *tty)
@@ -393,7 +499,10 @@ static int acm_tty_chars_in_buffer(struct tty_struct *tty)
struct acm *acm = tty->driver_data;
if (!ACM_READY(acm))
return -EINVAL;
- return !acm->ready_for_write ? acm->writeurb->transfer_buffer_length : 0;
+ /*
+ * This is inaccurate (overcounts), but it works.
+ */
+ return (ACM_NWB - acm_wb_is_avail(acm)) * acm->writesize;
}
static void acm_tty_throttle(struct tty_struct *tty)
@@ -526,6 +635,39 @@ static void acm_tty_set_termios(struct tty_struct *tty, struct termios *termios_
* USB probe and disconnect routines.
*/
+/* Little helper: write buffers free */
+static void acm_write_buffers_free(struct acm *acm)
+{
+ int i;
+ struct acm_wb *wb;
+
+ for (wb = &acm->wb[0], i = 0; i < ACM_NWB; i++, wb++) {
+ usb_buffer_free(acm->dev, acm->writesize, wb->buf, wb->dmah);
+ }
+}
+
+/* Little helper: write buffers allocate */
+static int acm_write_buffers_alloc(struct acm *acm)
+{
+ int i;
+ struct acm_wb *wb;
+
+ for (wb = &acm->wb[0], i = 0; i < ACM_NWB; i++, wb++) {
+ wb->buf = usb_buffer_alloc(acm->dev, acm->writesize, GFP_KERNEL,
+ &wb->dmah);
+ if (!wb->buf) {
+ while (i != 0) {
+ --i;
+ --wb;
+ usb_buffer_free(acm->dev, acm->writesize,
+ wb->buf, wb->dmah);
+ }
+ return -ENOMEM;
+ }
+ }
+ return 0;
+}
+
static int acm_probe (struct usb_interface *intf,
const struct usb_device_id *id)
{
@@ -700,7 +842,8 @@ skip_normal_probe:
acm->bh.data = (unsigned long) acm;
INIT_WORK(&acm->work, acm_softint, acm);
spin_lock_init(&acm->throttle_lock);
- acm->ready_for_write = 1;
+ spin_lock_init(&acm->write_lock);
+ acm->write_ready = 1;
buf = usb_buffer_alloc(usb_dev, ctrlsize, GFP_KERNEL, &acm->ctrl_dma);
if (!buf) {
@@ -716,12 +859,10 @@ skip_normal_probe:
}
acm->read_buffer = buf;
- buf = usb_buffer_alloc(usb_dev, acm->writesize, GFP_KERNEL, &acm->write_dma);
- if (!buf) {
+ if (acm_write_buffers_alloc(acm) < 0) {
dev_dbg(&intf->dev, "out of memory (write buffer alloc)\n");
goto alloc_fail4;
}
- acm->write_buffer = buf;
acm->ctrlurb = usb_alloc_urb(0, GFP_KERNEL);
if (!acm->ctrlurb) {
@@ -750,9 +891,9 @@ skip_normal_probe:
acm->readurb->transfer_dma = acm->read_dma;
usb_fill_bulk_urb(acm->writeurb, usb_dev, usb_sndbulkpipe(usb_dev, epwrite->bEndpointAddress),
- acm->write_buffer, acm->writesize, acm_write_bulk, acm);
+ NULL, acm->writesize, acm_write_bulk, acm);
acm->writeurb->transfer_flags |= URB_NO_FSBR | URB_NO_TRANSFER_DMA_MAP;
- acm->writeurb->transfer_dma = acm->write_dma;
+ /* acm->writeurb->transfer_dma = 0; */
dev_info(&intf->dev, "ttyACM%d: USB ACM device\n", minor);
@@ -775,7 +916,7 @@ alloc_fail7:
alloc_fail6:
usb_free_urb(acm->ctrlurb);
alloc_fail5:
- usb_buffer_free(usb_dev, acm->writesize, acm->write_buffer, acm->write_dma);
+ acm_write_buffers_free(acm);
alloc_fail4:
usb_buffer_free(usb_dev, readsize, acm->read_buffer, acm->read_dma);
alloc_fail3:
@@ -806,7 +947,7 @@ static void acm_disconnect(struct usb_interface *intf)
flush_scheduled_work(); /* wait for acm_softint */
- usb_buffer_free(usb_dev, acm->writesize, acm->write_buffer, acm->write_dma);
+ acm_write_buffers_free(acm);
usb_buffer_free(usb_dev, acm->readsize, acm->read_buffer, acm->read_dma);
usb_buffer_free(usb_dev, acm->ctrlsize, acm->ctrl_buffer, acm->ctrl_dma);
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