2 files changed, 47 insertions, 10 deletions

diff --git a/drivers/serial/8250.c b/drivers/serial/8250.c
index 30e8beb71430..79f67fd863ec 100644
--- a/drivers/serial/8250.c
+++ b/drivers/serial/8250.c
@@ -132,9 +132,9 @@ struct uart_8250_port {
         struct uart_port        port;
         struct timer_list       timer;          /* "no irq" timer */
         struct list_head        list;           /* ports on this IRQ */
-        unsigned int            capabilities;   /* port capabilities */
+        unsigned short          capabilities;   /* port capabilities */
+        unsigned short          bugs;           /* port bugs */
         unsigned int            tx_loadsz;      /* transmit fifo load size */
-        unsigned short          rev;
         unsigned char           acr;
         unsigned char           ier;
         unsigned char           lcr;
@@ -560,7 +560,14 @@ static void autoconfig_has_efr(struct uart_8250_port *up)
         if (id1 == 0x16 && id2 == 0xC9 &&
             (id3 == 0x50 || id3 == 0x52 || id3 == 0x54)) {
                 up->port.type = PORT_16C950;
-                up->rev = rev | (id3 << 8);
+
+                /*
+                 * Enable work around for the Oxford Semiconductor 952 rev B
+                 * chip which causes it to seriously miscalculate baud rates
+                 * when DLL is 0.
+                 */
+                if (id3 == 0x52 && rev == 0x01)
+                        up->bugs |= UART_BUG_QUOT;
                 return;
         }
         
@@ -577,8 +584,6 @@ static void autoconfig_has_efr(struct uart_8250_port *up)
 
         id2 = id1 >> 8;
         if (id2 == 0x10 || id2 == 0x12 || id2 == 0x14) {
-                if (id2 == 0x10)
-                        up->rev = id1 & 255;
                 up->port.type = PORT_16850;
                 return;
         }
@@ -809,6 +814,7 @@ static void autoconfig(struct uart_8250_port *up, unsigned int probeflags)
 //      save_flags(flags); cli();
 
         up->capabilities = 0;
+        up->bugs = 0;
 
         if (!(up->port.flags & UPF_BUGGY_UART)) {
                 /*
@@ -1021,6 +1027,8 @@ static void serial8250_stop_tx(struct uart_port *port, unsigned int tty_stop)
         }
 }
 
+static void transmit_chars(struct uart_8250_port *up);
+
 static void serial8250_start_tx(struct uart_port *port, unsigned int tty_start)
 {
         struct uart_8250_port *up = (struct uart_8250_port *)port;
@@ -1028,6 +1036,14 @@ static void serial8250_start_tx(struct uart_port *port, unsigned int tty_start)
         if (!(up->ier & UART_IER_THRI)) {
                 up->ier |= UART_IER_THRI;
                 serial_out(up, UART_IER, up->ier);
+
+                if (up->bugs & UART_BUG_TXEN) {
+                        unsigned char lsr, iir;
+                        lsr = serial_in(up, UART_LSR);
+                        iir = serial_in(up, UART_IIR);
+                        if (lsr & UART_LSR_TEMT && iir & UART_IIR_NO_INT)
+                                transmit_chars(up);
+                }
         }
         /*
          * We only do this from uart_start
@@ -1433,6 +1449,7 @@ static int serial8250_startup(struct uart_port *port)
 {
         struct uart_8250_port *up = (struct uart_8250_port *)port;
         unsigned long flags;
+        unsigned char lsr, iir;
         int retval;
 
         up->capabilities = uart_config[up->port.type].flags;
@@ -1536,6 +1553,26 @@ static int serial8250_startup(struct uart_port *port)
                         up->port.mctrl |= TIOCM_OUT2;
 
         serial8250_set_mctrl(&up->port, up->port.mctrl);
+
+        /*
+         * Do a quick test to see if we receive an
+         * interrupt when we enable the TX irq.
+         */
+        serial_outp(up, UART_IER, UART_IER_THRI);
+        lsr = serial_in(up, UART_LSR);
+        iir = serial_in(up, UART_IIR);
+        serial_outp(up, UART_IER, 0);
+
+        if (lsr & UART_LSR_TEMT && iir & UART_IIR_NO_INT) {
+                if (!(up->bugs & UART_BUG_TXEN)) {
+                        up->bugs |= UART_BUG_TXEN;
+                        pr_debug("ttyS%d - enabling bad tx status workarounds\n",
+                                 port->line);
+                }
+        } else {
+                up->bugs &= ~UART_BUG_TXEN;
+        }
+
         spin_unlock_irqrestore(&up->port.lock, flags);
 
         /*
@@ -1677,12 +1714,9 @@ serial8250_set_termios(struct uart_port *port, struct termios *termios,
         quot = serial8250_get_divisor(port, baud);
 
         /*
-         * Work around a bug in the Oxford Semiconductor 952 rev B
-         * chip which causes it to seriously miscalculate baud rates
-         * when DLL is 0.
+         * Oxford Semi 952 rev B workaround
          */
-        if ((quot & 0xff) == 0 && up->port.type == PORT_16C950 &&
-            up->rev == 0x5201)
+        if (up->bugs & UART_BUG_QUOT && (quot & 0xff) == 0)
                 quot ++;
 
         if (up->capabilities & UART_CAP_FIFO && up->port.fifosize > 1) {
diff --git a/drivers/serial/8250.h b/drivers/serial/8250.h
index 4f3d62f222f4..9225c82faeb8 100644
--- a/drivers/serial/8250.h
+++ b/drivers/serial/8250.h
@@ -51,6 +51,9 @@ struct serial8250_config {
 #define UART_CAP_AFE    (1 << 11)       /* MCR-based hw flow control */
 #define UART_CAP_UUE    (1 << 12)       /* UART needs IER bit 6 set (Xscale) */
 
+#define UART_BUG_QUOT   (1 << 0)        /* UART has buggy quot LSB */
+#define UART_BUG_TXEN   (1 << 1)        /* UART has buggy TX IIR status */
+
 #if defined(__i386__) && (defined(CONFIG_M386) || defined(CONFIG_M486))
 #define _INLINE_ inline
 #else