Blackfin Serial Driver: Use timer to poll CTS PIN instead of workqueue.

This allows other threads to run when the serial driver polls the CTS
PIN in a loop.

Signed-off-by: Sonic Zhang <sonic.zhang@analog.com>
Signed-off-by: Bryan Wu <cooloney@kernel.org>

1 files changed, 18 insertions, 22 deletions

diff --git a/drivers/serial/bfin_5xx.c b/drivers/serial/bfin_5xx.c
index f20952c43cb8..fd9bb777df28 100644
--- a/drivers/serial/bfin_5xx.c
+++ b/drivers/serial/bfin_5xx.c
@@ -49,6 +49,7 @@
 #define DMA_RX_YCOUNT           (PAGE_SIZE / DMA_RX_XCOUNT)
 
 #define DMA_RX_FLUSH_JIFFIES    (HZ / 50)
+#define CTS_CHECK_JIFFIES       (HZ / 50)
 
 #ifdef CONFIG_SERIAL_BFIN_DMA
 static void bfin_serial_dma_tx_chars(struct bfin_serial_port *uart);
@@ -290,11 +291,6 @@ static void bfin_serial_tx_chars(struct bfin_serial_port *uart)
 {
         struct circ_buf *xmit = &uart->port.info->xmit;
 
-        if (uart->port.x_char) {
-                UART_PUT_CHAR(uart, uart->port.x_char);
-                uart->port.icount.tx++;
-                uart->port.x_char = 0;
-        }
         /*
          * Check the modem control lines before
          * transmitting anything.
@@ -306,6 +302,12 @@ static void bfin_serial_tx_chars(struct bfin_serial_port *uart)
                 return;
         }
 
+        if (uart->port.x_char) {
+                UART_PUT_CHAR(uart, uart->port.x_char);
+                uart->port.icount.tx++;
+                uart->port.x_char = 0;
+        }
+
         while ((UART_GET_LSR(uart) & THRE) && xmit->tail != xmit->head) {
                 UART_PUT_CHAR(uart, xmit->buf[xmit->tail]);
                 xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
@@ -345,15 +347,6 @@ static irqreturn_t bfin_serial_tx_int(int irq, void *dev_id)
 }
 #endif
 
-#ifdef CONFIG_SERIAL_BFIN_CTSRTS
-static void bfin_serial_do_work(struct work_struct *work)
-{
-        struct bfin_serial_port *uart = container_of(work, struct bfin_serial_port, cts_workqueue);
-
-        bfin_serial_mctrl_check(uart);
-}
-#endif
-
 #ifdef CONFIG_SERIAL_BFIN_DMA
 static void bfin_serial_dma_tx_chars(struct bfin_serial_port *uart)
 {
@@ -361,6 +354,12 @@ static void bfin_serial_dma_tx_chars(struct bfin_serial_port *uart)
 
         uart->tx_done = 0;
 
+        /*
+         * Check the modem control lines before
+         * transmitting anything.
+         */
+        bfin_serial_mctrl_check(uart);
+
         if (uart_circ_empty(xmit) || uart_tx_stopped(&uart->port)) {
                 uart->tx_count = 0;
                 uart->tx_done = 1;
@@ -373,12 +372,6 @@ static void bfin_serial_dma_tx_chars(struct bfin_serial_port *uart)
                 uart->port.x_char = 0;
         }
 
-        /*
-         * Check the modem control lines before
-         * transmitting anything.
-         */
-        bfin_serial_mctrl_check(uart);
-
         uart->tx_count = CIRC_CNT(xmit->head, xmit->tail, UART_XMIT_SIZE);
         if (uart->tx_count > (UART_XMIT_SIZE - xmit->tail))
                 uart->tx_count = UART_XMIT_SIZE - xmit->tail;
@@ -565,7 +558,10 @@ static void bfin_serial_mctrl_check(struct bfin_serial_port *uart)
         uart_handle_cts_change(&uart->port, status & TIOCM_CTS);
         if (!(status & TIOCM_CTS)) {
                 tty->hw_stopped = 1;
-                schedule_work(&uart->cts_workqueue);
+                uart->cts_timer.data = (unsigned long)(uart);
+                uart->cts_timer.function = (void *)bfin_serial_mctrl_check;
+                uart->cts_timer.expires = jiffies + CTS_CHECK_JIFFIES;
+                add_timer(&(uart->cts_timer));
         } else {
                 tty->hw_stopped = 0;
         }
@@ -885,7 +881,7 @@ static void __init bfin_serial_init_ports(void)
                 init_timer(&(bfin_serial_ports[i].rx_dma_timer));
 #endif
 #ifdef CONFIG_SERIAL_BFIN_CTSRTS
-                INIT_WORK(&bfin_serial_ports[i].cts_workqueue, bfin_serial_do_work);
+                init_timer(&(bfin_serial_ports[i].cts_timer));
                 bfin_serial_ports[i].cts_pin        =
                         bfin_serial_resource[i].uart_cts_pin;
                 bfin_serial_ports[i].rts_pin        =