serial driver PMC MSP71xx

Serial driver patch for the PMC-Sierra MSP71xx devices.

There are three different fixes:

1 Fix for DesignWare APB THRE errata: In brief, this is a non-standard
  16550 in that the THRE interrupt will not re-assert itself simply by
  disabling and re-enabling the THRI bit in the IER, it is only re-enabled
  if a character is actually sent out.

  It appears that the "8250-uart-backup-timer.patch" in the "mm" tree
  also fixes it so we have dropped our initial workaround.  This patch now
  needs to be applied on top of that "mm" patch.

2 Fix for Busy Detect on LCR write: The DesignWare APB UART has a feature
  which causes a new Busy Detect interrupt to be generated if it's busy
  when the LCR is written.  This fix saves the value of the LCR and
  rewrites it after clearing the interrupt.

3 Workaround for interrupt/data concurrency issue: The SoC needs to
  ensure that writes that can cause interrupts to be cleared reach the UART
  before returning from the ISR.  This fix reads a non-destructive register
  on the UART so the read transaction completion ensures the previously
  queued write transaction has also completed.
Signed-off-by: Marc St-Jean <Marc_St-Jean@pmc-sierra.com>
Cc: Russell King <rmk@arm.linux.org.uk>
Cc: Ralf Baechle <ralf@linux-mips.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

arch/mips/pmc-sierra/msp71xx/msp_serial.c

+/*
+ * The setup file for serial related hardware on PMC-Sierra MSP processors.
+ *
+ * Copyright 2005 PMC-Sierra, Inc.
+ *
+ *  This program is free software; you can redistribute  it and/or modify it
+ *  under  the terms of  the GNU General  Public License as published by the
+ *  Free Software Foundation;  either version 2 of the  License, or (at your
+ *  option) any later version.
+ *
+ *  THIS  SOFTWARE  IS PROVIDED   ``AS  IS'' AND   ANY  EXPRESS OR IMPLIED
+ *  WARRANTIES,   INCLUDING, BUT NOT  LIMITED  TO, THE IMPLIED WARRANTIES OF
+ *  MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN
+ *  NO  EVENT  SHALL   THE AUTHOR  BE    LIABLE FOR ANY   DIRECT, INDIRECT,
+ *  INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
+ *  NOT LIMITED   TO, PROCUREMENT OF  SUBSTITUTE GOODS  OR SERVICES; LOSS OF
+ *  USE, DATA,  OR PROFITS; OR  BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
+ *  ANY THEORY OF LIABILITY, WHETHER IN  CONTRACT, STRICT LIABILITY, OR TORT
+ *  (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
+ *  THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ *  You should have received a copy of the  GNU General Public License along
+ *  with this program; if not, write  to the Free Software Foundation, Inc.,
+ *  675 Mass Ave, Cambridge, MA 02139, USA.
+ */
+
+#include <linux/serial.h>
+#include <linux/serial_core.h>
+#include <linux/serial_reg.h>
+
+#include <asm/bootinfo.h>
+#include <asm/io.h>
+#include <asm/processor.h>
+#include <asm/serial.h>
+
+#include <msp_prom.h>
+#include <msp_int.h>
+#include <msp_regs.h>
+
+#ifdef CONFIG_KGDB
+/*
+ * kgdb uses serial port 1 so the console can remain on port 0.
+ * To use port 0 change the definition to read as follows:
+ * #define DEBUG_PORT_BASE KSEG1ADDR(MSP_UART0_BASE)
+ */
+#define DEBUG_PORT_BASE KSEG1ADDR(MSP_UART1_BASE)
+
+int putDebugChar(char c)
+{
+	volatile uint32_t *uart = (volatile uint32_t *)DEBUG_PORT_BASE;
+	uint32_t val = (uint32_t)c;
+
+	local_irq_disable();
+	while( !(uart[5] & 0x20) ); /* Wait for TXRDY */
+	uart[0] = val;
+	while( !(uart[5] & 0x20) ); /* Wait for TXRDY */
+	local_irq_enable();
+
+	return 1;
+}
+
+char getDebugChar(void)
+{
+	volatile uint32_t *uart = (volatile uint32_t *)DEBUG_PORT_BASE;
+	uint32_t val;
+
+	while( !(uart[5] & 0x01) ); /* Wait for RXRDY */
+	val = uart[0];
+
+	return (char)val;
+}
+
+void initDebugPort(unsigned int uartclk, unsigned int baudrate)
+{
+	unsigned int baud_divisor = (uartclk + 8 * baudrate)/(16 * baudrate);
+
+	/* Enable FIFOs */
+	writeb(UART_FCR_ENABLE_FIFO | UART_FCR_CLEAR_RCVR |
+			UART_FCR_CLEAR_XMIT | UART_FCR_TRIGGER_4,
+		(char *)DEBUG_PORT_BASE + (UART_FCR * 4));
+
+	/* Select brtc divisor */
+	writeb(UART_LCR_DLAB, (char *)DEBUG_PORT_BASE + (UART_LCR * 4));
+
+	/* Store divisor lsb */
+	writeb(baud_divisor, (char *)DEBUG_PORT_BASE + (UART_TX * 4));
+
+	/* Store divisor msb */
+	writeb(baud_divisor >> 8, (char *)DEBUG_PORT_BASE + (UART_IER * 4));
+
+	/* Set 8N1 mode */
+	writeb(UART_LCR_WLEN8, (char *)DEBUG_PORT_BASE + (UART_LCR * 4));
+
+	/* Disable flow control */
+	writeb(0, (char *)DEBUG_PORT_BASE + (UART_MCR * 4));
+
+	/* Disable receive interrupt(!) */
+	writeb(0, (char *)DEBUG_PORT_BASE + (UART_IER * 4));
+}
+#endif
+
+void __init msp_serial_setup(void)
+{
+	char    *s;
+	char    *endp;
+	struct uart_port up;
+	unsigned int uartclk;
+
+	memset(&up, 0, sizeof(up));
+
+	/* Check if clock was specified in environment */
+	s = prom_getenv("uartfreqhz");
+	if(!(s && *s && (uartclk = simple_strtoul(s, &endp, 10)) && *endp == 0))
+		uartclk = MSP_BASE_BAUD;
+	ppfinit("UART clock set to %d\n", uartclk);
+
+	/* Initialize first serial port */
+	up.mapbase      = MSP_UART0_BASE;
+	up.membase      = ioremap_nocache(up.mapbase,MSP_UART_REG_LEN);
+	up.irq          = MSP_INT_UART0;
+	up.uartclk      = uartclk;
+	up.regshift     = 2;
+	up.iotype       = UPIO_DWAPB; /* UPIO_MEM like */
+	up.flags        = STD_COM_FLAGS;
+	up.type         = PORT_16550A;
+	up.line         = 0;
+	up.private_data		= (void*)UART0_STATUS_REG;
+	if (early_serial_setup(&up))
+		printk(KERN_ERR "Early serial init of port 0 failed\n");
+
+	/* Initialize the second serial port, if one exists */
+	switch (mips_machtype) {
+		case MACH_MSP4200_EVAL:
+		case MACH_MSP4200_GW:
+		case MACH_MSP4200_FPGA:
+		case MACH_MSP7120_EVAL:
+		case MACH_MSP7120_GW:
+		case MACH_MSP7120_FPGA:
+			/* Enable UART1 on MSP4200 and MSP7120 */
+			*GPIO_CFG2_REG = 0x00002299;
+
+#ifdef CONFIG_KGDB
+			/* Initialize UART1 for kgdb since PMON doesn't */
+			if( DEBUG_PORT_BASE == KSEG1ADDR(MSP_UART1_BASE) ) {
+				if( mips_machtype == MACH_MSP4200_FPGA
+				 || mips_machtype == MACH_MSP7120_FPGA )
+					initDebugPort(uartclk,19200);
+				else
+					initDebugPort(uartclk,57600);
+			}
+#endif
+			break;
+
+		default:
+			return; /* No second serial port, good-bye. */
+	}
+
+	up.mapbase      = MSP_UART1_BASE;
+	up.membase      = ioremap_nocache(up.mapbase,MSP_UART_REG_LEN);
+	up.irq          = MSP_INT_UART1;
+	up.line         = 1;
+	up.private_data		= (void*)UART1_STATUS_REG;
+	if (early_serial_setup(&up))
+		printk(KERN_ERR "Early serial init of port 1 failed\n");
+}

drivers/serial/8250.c

@@ -308,6 +308,7 @@ static unsigned int serial_in(struct uart_8250_port *up, int offset)
 		return inb(up->port.iobase + 1);
 
 	case UPIO_MEM:
+	case UPIO_DWAPB:
 		return readb(up->port.membase + offset);
 
 	case UPIO_MEM32:
@@ -333,6 +334,8 @@ static unsigned int serial_in(struct uart_8250_port *up, int offset)
 static void
 serial_out(struct uart_8250_port *up, int offset, int value)
 {
+	/* Save the offset before it's remapped */
+	int save_offset = offset;
 	offset = map_8250_out_reg(up, offset) << up->port.regshift;
 
 	switch (up->port.iotype) {
@@ -359,6 +362,18 @@ serial_out(struct uart_8250_port *up, int offset, int value)
 			writeb(value, up->port.membase + offset);
 		break;
 
+	case UPIO_DWAPB:
+		/* Save the LCR value so it can be re-written when a
+		 * Busy Detect interrupt occurs. */
+		if (save_offset == UART_LCR)
+			up->lcr = value;
+		writeb(value, up->port.membase + offset);
+		/* Read the IER to ensure any interrupt is cleared before
+		 * returning from ISR. */
+		if (save_offset == UART_TX || save_offset == UART_IER)
+			value = serial_in(up, UART_IER);
+		break;
+
 	default:
 		outb(value, up->port.iobase + offset);
 	}
@@ -373,6 +388,7 @@ serial_out_sync(struct uart_8250_port *up, int offset, int value)
 #ifdef CONFIG_SERIAL_8250_AU1X00
 	case UPIO_AU:
 #endif
+	case UPIO_DWAPB:
 		serial_out(up, offset, value);
 		serial_in(up, UART_LCR);	/* safe, no side-effects */
 		break;
@@ -1388,6 +1404,19 @@ static irqreturn_t serial8250_interrupt(int irq, void *dev_id)
 
 			handled = 1;
 
+			end = NULL;
+		} else if (up->port.iotype == UPIO_DWAPB &&
+			  (iir & UART_IIR_BUSY) == UART_IIR_BUSY) {
+			/* The DesignWare APB UART has an Busy Detect (0x07)
+			 * interrupt meaning an LCR write attempt occured while the
+			 * UART was busy. The interrupt must be cleared by reading
+			 * the UART status register (USR) and the LCR re-written. */
+			unsigned int status;
+			status = *(volatile u32 *)up->port.private_data;
+			serial_out(up, UART_LCR, up->lcr);
+
+			handled = 1;
+
 			end = NULL;
 		} else if (end == NULL)
 			end = l;
@@ -2090,6 +2119,7 @@ static int serial8250_request_std_resource(struct uart_8250_port *up)
 	case UPIO_TSI:
 	case UPIO_MEM32:
 	case UPIO_MEM:
+	case UPIO_DWAPB:
 		if (!up->port.mapbase)
 			break;
 
@@ -2127,6 +2157,7 @@ static void serial8250_release_std_resource(struct uart_8250_port *up)
 	case UPIO_TSI:
 	case UPIO_MEM32:
 	case UPIO_MEM:
+	case UPIO_DWAPB:
 		if (!up->port.mapbase)
 			break;
 

drivers/serial/serial_core.c

@@ -2064,6 +2064,7 @@ uart_report_port(struct uart_driver *drv, struct uart_port *port)
 	case UPIO_MEM32:
 	case UPIO_AU:
 	case UPIO_TSI:
+	case UPIO_DWAPB:
 		snprintf(address, sizeof(address),
 			 "MMIO 0x%lx", port->mapbase);
 		break;
@@ -2409,6 +2410,7 @@ int uart_match_port(struct uart_port *port1, struct uart_port *port2)
 	case UPIO_MEM32:
 	case UPIO_AU:
 	case UPIO_TSI:
+	case UPIO_DWAPB:
 		return (port1->mapbase == port2->mapbase);
 	}
 	return 0;

include/linux/serial_core.h

@@ -230,6 +230,7 @@ struct uart_port {
 #define UPIO_MEM32		(3)
 #define UPIO_AU			(4)			/* Au1x00 type IO */
 #define UPIO_TSI		(5)			/* Tsi108/109 type IO */
+#define UPIO_DWAPB		(6)			/* DesignWare APB UART */
 
 	unsigned int		read_status_mask;	/* driver specific */
 	unsigned int		ignore_status_mask;	/* driver specific */
@@ -276,6 +277,7 @@ struct uart_port {
 	struct device		*dev;			/* parent device */
 	unsigned char		hub6;			/* this should be in the 8250 driver */
 	unsigned char		unused[3];
+	void			*private_data;		/* generic platform data pointer */
 };
 
 /*

include/linux/serial_reg.h

@@ -38,6 +38,8 @@
 #define UART_IIR_RDI		0x04 /* Receiver data interrupt */
 #define UART_IIR_RLSI		0x06 /* Receiver line status interrupt */
 
+#define UART_IIR_BUSY		0x07 /* DesignWare APB Busy Detect */
+
 #define UART_FCR	2	/* Out: FIFO Control Register */
 #define UART_FCR_ENABLE_FIFO	0x01 /* Enable the FIFO */
 #define UART_FCR_CLEAR_RCVR	0x02 /* Clear the RCVR FIFO */