#include <linux/mm.h>
#include <linux/seq_file.h>
#include <linux/slab.h>
+#include <linux/smp_lock.h>
#include <linux/netdevice.h>
#include <linux/vmalloc.h>
#include <linux/init.h>
static unsigned int tbuf_bytes(struct slgt_info *info);
static void reset_tbufs(struct slgt_info *info);
static void tdma_reset(struct slgt_info *info);
-static void tdma_start(struct slgt_info *info);
-static void tx_load(struct slgt_info *info, const char *buf, unsigned int count);
+static bool tx_load(struct slgt_info *info, const char *buf, unsigned int count);
static void get_signals(struct slgt_info *info);
static void set_signals(struct slgt_info *info);
}
}
+static void update_tx_timer(struct slgt_info *info)
+{
+ /*
+ * use worst case speed of 1200bps to calculate transmit timeout
+ * based on data in buffers (tbuf_bytes) and FIFO (128 bytes)
+ */
+ if (info->params.mode == MGSL_MODE_HDLC) {
+ int timeout = (tbuf_bytes(info) * 7) + 1000;
+ mod_timer(&info->tx_timer, jiffies + msecs_to_jiffies(timeout));
+ }
+}
+
static int write(struct tty_struct *tty,
const unsigned char *buf, int count)
{
int ret = 0;
struct slgt_info *info = tty->driver_data;
unsigned long flags;
- unsigned int bufs_needed;
if (sanity_check(info, tty->name, "write"))
- goto cleanup;
+ return -EIO;
+
DBGINFO(("%s write count=%d\n", info->device_name, count));
- if (!info->tx_buf)
- goto cleanup;
+ if (!info->tx_buf || (count > info->max_frame_size))
+ return -EIO;
- if (count > info->max_frame_size) {
- ret = -EIO;
- goto cleanup;
- }
+ if (!count || tty->stopped || tty->hw_stopped)
+ return 0;
- if (!count)
- goto cleanup;
+ spin_lock_irqsave(&info->lock, flags);
- if (!info->tx_active && info->tx_count) {
+ if (info->tx_count) {
/* send accumulated data from send_char() */
- tx_load(info, info->tx_buf, info->tx_count);
- goto start;
+ if (!tx_load(info, info->tx_buf, info->tx_count))
+ goto cleanup;
+ info->tx_count = 0;
}
- bufs_needed = (count/DMABUFSIZE);
- if (count % DMABUFSIZE)
- ++bufs_needed;
- if (bufs_needed > free_tbuf_count(info))
- goto cleanup;
- ret = info->tx_count = count;
- tx_load(info, buf, count);
- goto start;
-
-start:
- if (info->tx_count && !tty->stopped && !tty->hw_stopped) {
- spin_lock_irqsave(&info->lock,flags);
- if (!info->tx_active)
- tx_start(info);
- else
- tdma_start(info);
- spin_unlock_irqrestore(&info->lock,flags);
- }
+ if (tx_load(info, buf, count))
+ ret = count;
cleanup:
+ spin_unlock_irqrestore(&info->lock, flags);
DBGINFO(("%s write rc=%d\n", info->device_name, ret));
return ret;
}
if (!info->tx_buf)
return 0;
spin_lock_irqsave(&info->lock,flags);
- if (!info->tx_active && (info->tx_count < info->max_frame_size)) {
+ if (info->tx_count < info->max_frame_size) {
info->tx_buf[info->tx_count++] = ch;
ret = 1;
}
DBGINFO(("%s flush_chars start transmit\n", info->device_name));
spin_lock_irqsave(&info->lock,flags);
- if (!info->tx_active && info->tx_count) {
- tx_load(info, info->tx_buf,info->tx_count);
- tx_start(info);
- }
+ if (info->tx_count && tx_load(info, info->tx_buf, info->tx_count))
+ info->tx_count = 0;
spin_unlock_irqrestore(&info->lock,flags);
}
return;
DBGINFO(("%s flush_buffer\n", info->device_name));
- spin_lock_irqsave(&info->lock,flags);
- if (!info->tx_active)
- info->tx_count = 0;
- spin_unlock_irqrestore(&info->lock,flags);
+ spin_lock_irqsave(&info->lock, flags);
+ info->tx_count = 0;
+ spin_unlock_irqrestore(&info->lock, flags);
tty_wakeup(tty);
}
if (sanity_check(info, tty->name, "tx_release"))
return;
DBGINFO(("%s tx_release\n", info->device_name));
- spin_lock_irqsave(&info->lock,flags);
- if (!info->tx_active && info->tx_count) {
- tx_load(info, info->tx_buf, info->tx_count);
- tx_start(info);
- }
- spin_unlock_irqrestore(&info->lock,flags);
+ spin_lock_irqsave(&info->lock, flags);
+ if (info->tx_count && tx_load(info, info->tx_buf, info->tx_count))
+ info->tx_count = 0;
+ spin_unlock_irqrestore(&info->lock, flags);
}
/*
*
* skb socket buffer containing HDLC frame
* dev pointer to network device structure
- *
- * returns 0 if success, otherwise error code
*/
-static int hdlcdev_xmit(struct sk_buff *skb, struct net_device *dev)
+static netdev_tx_t hdlcdev_xmit(struct sk_buff *skb,
+ struct net_device *dev)
{
struct slgt_info *info = dev_to_port(dev);
unsigned long flags;
DBGINFO(("%s hdlc_xmit\n", dev->name));
+ if (!skb->len)
+ return NETDEV_TX_OK;
+
/* stop sending until this frame completes */
netif_stop_queue(dev);
- /* copy data to device buffers */
- info->tx_count = skb->len;
- tx_load(info, skb->data, skb->len);
-
/* update network statistics */
dev->stats.tx_packets++;
dev->stats.tx_bytes += skb->len;
- /* done with socket buffer, so free it */
- dev_kfree_skb(skb);
-
/* save start time for transmit timeout detection */
dev->trans_start = jiffies;
- /* start hardware transmitter if necessary */
- spin_lock_irqsave(&info->lock,flags);
- if (!info->tx_active)
- tx_start(info);
- spin_unlock_irqrestore(&info->lock,flags);
+ spin_lock_irqsave(&info->lock, flags);
+ tx_load(info, skb->data, skb->len);
+ spin_unlock_irqrestore(&info->lock, flags);
- return 0;
+ /* done with socket buffer, so free it */
+ dev_kfree_skb(skb);
+
+ return NETDEV_TX_OK;
}
/**
if (info->params.mode == MGSL_MODE_ASYNC) {
if (status & IRQ_TXIDLE) {
- if (info->tx_count)
+ if (info->tx_active)
isr_txeom(info, status);
}
if (info->rx_pio && (status & IRQ_RXDATA))
}
}
+/*
+ * return true if there are unsent tx DMA buffers, otherwise false
+ *
+ * if there are unsent buffers then info->tbuf_start
+ * is set to index of first unsent buffer
+ */
+static bool unsent_tbufs(struct slgt_info *info)
+{
+ unsigned int i = info->tbuf_current;
+ bool rc = false;
+
+ /*
+ * search backwards from last loaded buffer (precedes tbuf_current)
+ * for first unsent buffer (desc_count > 0)
+ */
+
+ do {
+ if (i)
+ i--;
+ else
+ i = info->tbuf_count - 1;
+ if (!desc_count(info->tbufs[i]))
+ break;
+ info->tbuf_start = i;
+ rc = true;
+ } while (i != info->tbuf_current);
+
+ return rc;
+}
+
static void isr_txeom(struct slgt_info *info, unsigned short status)
{
DBGISR(("%s txeom status=%04x\n", info->device_name, status));
slgt_irq_off(info, IRQ_TXDATA + IRQ_TXIDLE + IRQ_TXUNDER);
tdma_reset(info);
- reset_tbufs(info);
if (status & IRQ_TXUNDER) {
unsigned short val = rd_reg16(info, TCR);
wr_reg16(info, TCR, (unsigned short)(val | BIT2)); /* set reset bit */
info->icount.txok++;
}
+ if (unsent_tbufs(info)) {
+ tx_start(info);
+ update_tx_timer(info);
+ return;
+ }
info->tx_active = false;
- info->tx_count = 0;
del_timer(&info->tx_timer);
info->tx_enabled = true;
}
- if (info->tx_count) {
+ if (desc_count(info->tbufs[info->tbuf_start])) {
info->drop_rts_on_tx_done = false;
if (info->params.mode != MGSL_MODE_ASYNC) {
slgt_irq_on(info, IRQ_TXUNDER + IRQ_TXIDLE);
/* clear tx idle and underrun status bits */
wr_reg16(info, SSR, (unsigned short)(IRQ_TXIDLE + IRQ_TXUNDER));
- if (info->params.mode == MGSL_MODE_HDLC)
- mod_timer(&info->tx_timer, jiffies +
- msecs_to_jiffies(5000));
} else {
slgt_irq_off(info, IRQ_TXDATA);
slgt_irq_on(info, IRQ_TXIDLE);
/* clear tx idle status bit */
wr_reg16(info, SSR, IRQ_TXIDLE);
}
- tdma_start(info);
+ /* set 1st descriptor address and start DMA */
+ wr_reg32(info, TDDAR, info->tbufs[info->tbuf_start].pdesc);
+ wr_reg32(info, TDCSR, BIT2 + BIT0);
info->tx_active = true;
}
}
-/*
- * start transmit DMA if inactive and there are unsent buffers
- */
-static void tdma_start(struct slgt_info *info)
-{
- unsigned int i;
-
- if (rd_reg32(info, TDCSR) & BIT0)
- return;
-
- /* transmit DMA inactive, check for unsent buffers */
- i = info->tbuf_start;
- while (!desc_count(info->tbufs[i])) {
- if (++i == info->tbuf_count)
- i = 0;
- if (i == info->tbuf_current)
- return;
- }
- info->tbuf_start = i;
-
- /* there are unsent buffers, start transmit DMA */
-
- /* reset needed if previous error condition */
- tdma_reset(info);
-
- /* set 1st descriptor address */
- wr_reg32(info, TDDAR, info->tbufs[info->tbuf_start].pdesc);
- wr_reg32(info, TDCSR, BIT2 + BIT0); /* IRQ + DMA enable */
-}
-
static void tx_stop(struct slgt_info *info)
{
unsigned short val;
}
/*
- * load transmit DMA buffer(s) with data
+ * load data into transmit DMA buffer ring and start transmitter if needed
+ * return true if data accepted, otherwise false (buffers full)
*/
-static void tx_load(struct slgt_info *info, const char *buf, unsigned int size)
+static bool tx_load(struct slgt_info *info, const char *buf, unsigned int size)
{
unsigned short count;
unsigned int i;
struct slgt_desc *d;
- if (size == 0)
- return;
+ /* check required buffer space */
+ if (DIV_ROUND_UP(size, DMABUFSIZE) > free_tbuf_count(info))
+ return false;
DBGDATA(info, buf, size, "tx");
+ /*
+ * copy data to one or more DMA buffers in circular ring
+ * tbuf_start = first buffer for this data
+ * tbuf_current = next free buffer
+ *
+ * Copy all data before making data visible to DMA controller by
+ * setting descriptor count of the first buffer.
+ * This prevents an active DMA controller from reading the first DMA
+ * buffers of a frame and stopping before the final buffers are filled.
+ */
+
info->tbuf_start = i = info->tbuf_current;
while (size) {
d = &info->tbufs[i];
- if (++i == info->tbuf_count)
- i = 0;
count = (unsigned short)((size > DMABUFSIZE) ? DMABUFSIZE : size);
memcpy(d->buf, buf, count);
else
set_desc_eof(*d, 0);
- set_desc_count(*d, count);
+ /* set descriptor count for all but first buffer */
+ if (i != info->tbuf_start)
+ set_desc_count(*d, count);
d->buf_count = count;
+
+ if (++i == info->tbuf_count)
+ i = 0;
}
info->tbuf_current = i;
+
+ /* set first buffer count to make new data visible to DMA controller */
+ d = &info->tbufs[info->tbuf_start];
+ set_desc_count(*d, d->buf_count);
+
+ /* start transmitter if needed and update transmit timeout */
+ if (!info->tx_active)
+ tx_start(info);
+ update_tx_timer(info);
+
+ return true;
}
static int register_test(struct slgt_info *info)
spin_lock_irqsave(&info->lock,flags);
async_mode(info);
rx_start(info);
- info->tx_count = count;
tx_load(info, buf, count);
- tx_start(info);
spin_unlock_irqrestore(&info->lock, flags);
/* wait for receive complete */
info->icount.txtimeout++;
}
spin_lock_irqsave(&info->lock,flags);
- info->tx_active = false;
- info->tx_count = 0;
+ tx_stop(info);
spin_unlock_irqrestore(&info->lock,flags);
#if SYNCLINK_GENERIC_HDLC
git://ftp.safe.ca / safe / jmp / linux-2.6 / blobdiff