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path: root/drivers/char/synclink_gt.c
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Diffstat (limited to 'drivers/char/synclink_gt.c')
-rw-r--r--drivers/char/synclink_gt.c59
1 files changed, 57 insertions, 2 deletions
diff --git a/drivers/char/synclink_gt.c b/drivers/char/synclink_gt.c
index 3cfc9e1f888..8511e2e43c1 100644
--- a/drivers/char/synclink_gt.c
+++ b/drivers/char/synclink_gt.c
@@ -214,6 +214,7 @@ struct slgt_desc
char *buf; /* virtual address of data buffer */
unsigned int pdesc; /* physical address of this descriptor */
dma_addr_t buf_dma_addr;
+ unsigned short buf_count;
};
#define set_desc_buffer(a,b) (a).pbuf = cpu_to_le32((unsigned int)(b))
@@ -466,6 +467,7 @@ static void tx_start(struct slgt_info *info);
static void tx_stop(struct slgt_info *info);
static void tx_set_idle(struct slgt_info *info);
static unsigned int free_tbuf_count(struct slgt_info *info);
+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);
@@ -1388,10 +1390,12 @@ done:
static int chars_in_buffer(struct tty_struct *tty)
{
struct slgt_info *info = tty->driver_data;
+ int count;
if (sanity_check(info, tty->name, "chars_in_buffer"))
return 0;
- DBGINFO(("%s chars_in_buffer()=%d\n", info->device_name, info->tx_count));
- return info->tx_count;
+ count = tbuf_bytes(info);
+ DBGINFO(("%s chars_in_buffer()=%d\n", info->device_name, count));
+ return count;
}
/*
@@ -4671,6 +4675,56 @@ static unsigned int free_tbuf_count(struct slgt_info *info)
}
/*
+ * return number of bytes in unsent transmit DMA buffers
+ * and the serial controller tx FIFO
+ */
+static unsigned int tbuf_bytes(struct slgt_info *info)
+{
+ unsigned int total_count = 0;
+ unsigned int i = info->tbuf_current;
+ unsigned int reg_value;
+ unsigned int count;
+ unsigned int active_buf_count = 0;
+
+ /*
+ * Add descriptor counts for all tx DMA buffers.
+ * If count is zero (cleared by DMA controller after read),
+ * the buffer is complete or is actively being read from.
+ *
+ * Record buf_count of last buffer with zero count starting
+ * from current ring position. buf_count is mirror
+ * copy of count and is not cleared by serial controller.
+ * If DMA controller is active, that buffer is actively
+ * being read so add to total.
+ */
+ do {
+ count = desc_count(info->tbufs[i]);
+ if (count)
+ total_count += count;
+ else if (!total_count)
+ active_buf_count = info->tbufs[i].buf_count;
+ if (++i == info->tbuf_count)
+ i = 0;
+ } while (i != info->tbuf_current);
+
+ /* read tx DMA status register */
+ reg_value = rd_reg32(info, TDCSR);
+
+ /* if tx DMA active, last zero count buffer is in use */
+ if (reg_value & BIT0)
+ total_count += active_buf_count;
+
+ /* add tx FIFO count = reg_value[15..8] */
+ total_count += (reg_value >> 8) & 0xff;
+
+ /* if transmitter active add one byte for shift register */
+ if (info->tx_active)
+ total_count++;
+
+ return total_count;
+}
+
+/*
* load transmit DMA buffer(s) with data
*/
static void tx_load(struct slgt_info *info, const char *buf, unsigned int size)
@@ -4708,6 +4762,7 @@ static void tx_load(struct slgt_info *info, const char *buf, unsigned int size)
set_desc_eof(*d, 0);
set_desc_count(*d, count);
+ d->buf_count = count;
}
info->tbuf_current = i;