[GIT PATCH] Serial updates

[Russell King <rmk+lkml@arm.linux.org.uk>]

This update changes the following files:

 drivers/serial/8250.c |   54 ++++++++++++++++++++++++++++++++++++++++----------
 drivers/serial/8250.h |    3 ++
 2 files changed, 47 insertions(+), 10 deletions(-)

through these changes:

From: Russell King: Thu Jun 23 15:05:41 BST 2005
	
	[PATCH] Serial: Mobility's 16550A ports need a helping hand
	
	The Mobility 16550A serial ports don't behave the same as standard
	16550A ports, and need a helping hand to get them going once the
	transmitter has drained and been disabled.
	
	Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

From: Russell King: Thu Jun 23 10:43:04 BST 2005
	
	[PATCH] Serial: Convert 8250 revision-based bug fixes to bug bitmask
	
	For some 8250 port types, we used to check the type of the port, and
	then determine whether the chip revision means the device is buggy.
	Instead, introduce a bit array, and set the appropriate bit(s) when
	we discover a buggy device.
	
	Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

Index: drivers/serial/8250.c
===================================================================
--- 06cba21e92755bf6b815221d5124ca0f9faf7985/drivers/serial/8250.c  (mode:100644)
+++ ba48375ac5262a8587eb6237134ed0aa57e7174a/drivers/serial/8250.c  (mode:100644)
@@ -132,9 +132,9 @@
 	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 @@
 	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 @@
 
 	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 @@
 //	save_flags(flags); cli();
 
 	up->capabilities = 0;
+	up->bugs = 0;
 
 	if (!(up->port.flags & UPF_BUGGY_UART)) {
 		/*
@@ -1021,6 +1027,8 @@
 	}
 }
 
+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 @@
 	if (!(up->ier & UART_IER_THRI)) {
 		up->ier |= UART_IER_THRI;
 		serial_out(up, UART_IER, up->ier);
+
+		if (up->capabilities & 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 @@
 {
 	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 @@
 			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->capabilities & UART_BUG_TXEN)) {
+			up->capabilities |= UART_BUG_TXEN;
+			pr_debug("ttyS%d - enabling bad tx status workarounds\n",
+				 port->line);
+		}
+	} else {
+		up->capabilities &= ~UART_BUG_TXEN;
+	}
+
 	spin_unlock_irqrestore(&up->port.lock, flags);
 
 	/*
@@ -1677,12 +1714,9 @@
 	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) {
Index: drivers/serial/8250.h
===================================================================
--- 06cba21e92755bf6b815221d5124ca0f9faf7985/drivers/serial/8250.h  (mode:100644)
+++ ba48375ac5262a8587eb6237134ed0aa57e7174a/drivers/serial/8250.h  (mode:100644)
@@ -51,6 +51,9 @@
 #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