From oliver@neukum.org Thu Apr 21 12:29:53 2005
From: Oliver Neukum <oliver@neukum.org>
To: greg@kroah.com
Subject: USB: fix acm trouble with terminals
Date: Thu, 21 Apr 2005 21:28:02 +0200
This patch fixes lost LF when ACM device is used with getty/login/bash,
in case of a modem which takes calls.
Signed-off-by: Pete Zaitcev <zaitcev@redhat.com>
Signed-off-by: Oliver Neukum <oliver@neukum.name>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
diff -urp -X dontdiff linux-2.6.12-rc1/drivers/usb/class/cdc-acm.c linux-2.6.12-rc1-lem/drivers/usb/class/cdc-acm.c
--- linux-2.6.12-rc1/drivers/usb/class/cdc-acm.c 2005-03-18 17:12:12.000000000 -0800
+++ linux-2.6.12-rc1-lem/drivers/usb/class/cdc-acm.c 2005-04-18 13:53:26.000000000 -0700
@@ -106,6 +106,111 @@ static int acm_ctrl_msg(struct acm *acm,
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
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_stru
{
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 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(struc
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 t
* 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_in
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);
diff -urp -X dontdiff linux-2.6.12-rc1/drivers/usb/class/cdc-acm.h linux-2.6.12-rc1-lem/drivers/usb/class/cdc-acm.h
--- linux-2.6.12-rc1/drivers/usb/class/cdc-acm.h 2005-03-18 17:12:12.000000000 -0800
+++ linux-2.6.12-rc1-lem/drivers/usb/class/cdc-acm.h 2005-03-19 17:09:44.000000000 -0800
@@ -51,14 +51,34 @@
* Internal driver structures.
*/
+/*
+ * The only reason to have several buffers is to accomodate assumptions
+ * in line disciplines. They ask for empty space amount, receive our URB size,
+ * and proceed to issue several 1-character writes, assuming they will fit.
+ * The very first write takes a complete URB. Fortunately, this only happens
+ * when processing onlcr, so we only need 2 buffers.
+ */
+#define ACM_NWB 2
+struct acm_wb {
+ unsigned char *buf;
+ dma_addr_t dmah;
+ int len;
+ int use;
+};
+
struct acm {
struct usb_device *dev; /* the corresponding usb device */
struct usb_interface *control; /* control interface */
struct usb_interface *data; /* data interface */
struct tty_struct *tty; /* the corresponding tty */
struct urb *ctrlurb, *readurb, *writeurb; /* urbs */
- u8 *ctrl_buffer, *read_buffer, *write_buffer; /* buffers of urbs */
- dma_addr_t ctrl_dma, read_dma, write_dma; /* dma handles of buffers */
+ u8 *ctrl_buffer, *read_buffer; /* buffers of urbs */
+ dma_addr_t ctrl_dma, read_dma; /* dma handles of buffers */
+ struct acm_wb wb[ACM_NWB];
+ int write_current; /* current write buffer */
+ int write_used; /* number of non-empty write buffers */
+ int write_ready; /* write urb is not running */
+ spinlock_t write_lock;
struct usb_cdc_line_coding line; /* bits, stop, parity */
struct work_struct work; /* work queue entry for line discipline waking up */
struct tasklet_struct bh; /* rx processing */
@@ -71,7 +91,6 @@ struct acm {
unsigned int minor; /* acm minor number */
unsigned char throttle; /* throttled by tty layer */
unsigned char clocal; /* termios CLOCAL */
- unsigned char ready_for_write; /* write urb can be used */
unsigned char resubmit_to_unthrottle; /* throtteling has disabled the read urb */
unsigned int ctrl_caps; /* control capabilities from the class specific header */
};
Signed-off-by: Pete Zaitcev <zaitcev@redhat.com>
-- Pete