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[PATCH] serial driver PMC MSP71xx, kernel linux-mips.git master

To: linux-mips@linux-mips.org
Subject: [PATCH] serial driver PMC MSP71xx, kernel linux-mips.git master
From: Marc St-Jean <Marc_St-Jean@pmc-sierra.com>
Date: Wed, 24 Jan 2007 16:00:46 -0800
Cc: linux-serial@vger.kernel.org, linux-kernel@vger.kernel.org
Original-recipient: rfc822;linux-mips@linux-mips.org
Sender: linux-mips-bounce@linux-mips.org
User-agent: Thunderbird 1.5.0.9 (X11/20061206)
Here is my second attempt at the serial driver patch for the
PMC-Sierra MSP71xx device.

There are three different fixes:
1. Fix for THRE errata
- I verified the UART_BUG_TXEN fix does not help with this erratum.
- I left our current fix in until I get our platform booting on
2.6.20-rc4 to try the mm tree "8250-uart-backup-timer.patch".
Feel free to ignore for now.

2. Fix for Busy Detect on LCR write
- Moved to new UPIO_DWAPB iotype. Because the new type is a memory
mapped device and there are several tests for UPIO_MEM, this involved
updating serial_core.c and 8250_early.c in addition to 8250.c.
- I tried implementing this totally in serial_in as suggested, but
it can't be done because of bit overlap between UART_IIR_NO_INT and
UART_IIR_BUSY. Also there is no way to set the interrupt "handled = 1"
from serial_in.

3. Workaround for interrupt/data concurrency issue
- Moved to new UPIO_DWAPB iotype.

Thanks,
Marc

Signed-off-by: Marc St-Jean <Marc_St-Jean@pmc-sierra.com>

Index: linux_2_6/drivers/serial/8250.c
===================================================================
RCS file: linux_2_6/drivers/serial/8250.c,v
retrieving revision 1.1.1.7
diff -u -r1.1.1.7 8250.c
--- linux_2_6/drivers/serial/8250.c     19 Oct 2006 21:00:58 -0000      1.1.1.7
+++ linux_2_6/drivers/serial/8250.c     24 Jan 2007 23:55:27 -0000
@@ -308,6 +308,7 @@
                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 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 +362,19 @@
                        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) &&
+                               in_irq())
+                       value = serial_in(up, UART_IER);
+               break;
+               
        default:
                outb(value, up->port.iobase + offset);
        }
@@ -1016,6 +1032,17 @@
                up->bugs |= UART_BUG_NOMSR;
  #endif

+       /* Workaround:
+        * The DesignWare SoC UART part has a bug for all
+        * versions before 3.03a (2005-07-18)
+        * 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.
+        */
+       if( up->port.flags & UPF_DW_THRE_BUG )
+               up->bugs |= UART_BUG_DWTHRE;
+
        serial_outp(up, UART_LCR, save_lcr);

        if (up->capabilities != uart_config[up->port.type].flags) {
@@ -1141,6 +1168,12 @@
                        iir = serial_in(up, UART_IIR);
                        if (lsr & UART_LSR_TEMT && iir & UART_IIR_NO_INT)
                                transmit_chars(up);
+               } else if (up->bugs & UART_BUG_DWTHRE) {
+                       unsigned char lsr, iir;
+                       lsr = serial_in(up, UART_LSR);
+                       iir = serial_in(up, UART_IIR);
+                       if (lsr & UART_LSR_THRE)
+                               transmit_chars(up);
                }
        }

@@ -1366,6 +1399,19 @@
                        handled = 1;

                        end = NULL;
+               } else if ((iir & UART_IIR_BUSY) == UART_IIR_BUSY &&
+                               up->port.iotype == UPIO_DWAPB) {
+                       /* The DesignWare APB UART has an Busy Detect (0x07)
+                        * interrupt meaning the LCR was written while the UART
+                        * was busy, so the LCR was not actually written. It's
+                        * cleared by reading the extended UART status 
register. */
+                       unsigned int status;
+                       status = *(volatile u32 *)up->port.user;
+                       serial_out(up, UART_LCR, up->lcr);                      
+
+                       handled = 1;
+
+                       end = NULL;
                } else if (end == NULL)
                        end = l;

@@ -1950,6 +1996,7 @@
                size = 0x100000;
                /* fall thru */
        case UPIO_MEM:
+       case UPIO_DWAPB:
                if (!up->port.mapbase)
                        break;

@@ -1985,6 +2032,7 @@
                size = 0x100000;
                /* fall thru */
        case UPIO_MEM:
+       case UPIO_DWAPB:
                if (!up->port.mapbase)
                        break;

@@ -2011,6 +2059,7 @@

        switch (up->port.iotype) {
        case UPIO_MEM:
+       case UPIO_DWAPB:
                ret = -EINVAL;
                break;

@@ -2032,6 +2081,7 @@

        switch (up->port.iotype) {
        case UPIO_MEM:
+       case UPIO_DWAPB:
                break;

        case UPIO_HUB6:
@@ -2352,9 +2402,12 @@

        add_preferred_console("ttyS", line, options);
        printk("Adding console on ttyS%d at %s 0x%lx (options '%s')\n",
-               line, port->iotype == UPIO_MEM ? "MMIO" : "I/O port",
-               port->iotype == UPIO_MEM ? (unsigned long) port->mapbase :
-                   (unsigned long) port->iobase, options);
+               line,
+               (port->iotype == UPIO_MEM || port->iotype == UPIO_DWAPB)
+                       ? "MMIO" : "I/O port",
+               (port->iotype == UPIO_MEM || port->iotype == UPIO_DWAPB)
+                       ? (unsigned long) port->mapbase : (unsigned long) 
port->iobase,
+               options);
        if (!(serial8250_console.flags & CON_ENABLED)) {
                serial8250_console.flags &= ~CON_PRINTBUFFER;
                register_console(&serial8250_console);
Index: linux_2_6/drivers/serial/8250.h
===================================================================
RCS file: linux_2_6/drivers/serial/8250.h,v
retrieving revision 1.1.1.6
retrieving revision 1.4
diff -u -r1.1.1.6 -r1.4
--- linux_2_6/drivers/serial/8250.h     19 Oct 2006 21:00:58 -0000      1.1.1.6
+++ linux_2_6/drivers/serial/8250.h     19 Oct 2006 22:08:15 -0000      1.4
@@ -49,6 +49,7 @@
  #define UART_BUG_QUOT (1 << 0)        /* UART has buggy quot LSB */
  #define UART_BUG_TXEN (1 << 1)        /* UART has buggy TX IIR status */
  #define UART_BUG_NOMSR        (1 << 2)        /* UART has buggy MSR status 
bits (Au1x00) */
+#define UART_BUG_DWTHRE (1 << 3)       /* UART has buggy DesignWare THRE 
interrupt re-assertion */

  #define PROBE_RSA     (1 << 0)
  #define PROBE_ANY     (~0)
Index: linux_2_6/drivers/serial/8250_early.c
===================================================================
RCS file: linux_2_6/drivers/serial/8250_early.c,v
retrieving revision 1.1.1.3
diff -u -r1.1.1.3 8250_early.c
--- linux_2_6/drivers/serial/8250_early.c       19 Oct 2006 20:08:20 -0000      
1.1.1.3
+++ linux_2_6/drivers/serial/8250_early.c       24 Jan 2007 23:55:27 -0000
@@ -46,7 +46,7 @@

  static unsigned int __init serial_in(struct uart_port *port, int offset)
  {
-       if (port->iotype == UPIO_MEM)
+       if (port->iotype == UPIO_MEM || port->iotype == UPIO_DWAPB)
                return readb(port->membase + offset);
        else
                return inb(port->iobase + offset);
@@ -54,7 +54,7 @@

  static void __init serial_out(struct uart_port *port, int offset, int value)
  {
-       if (port->iotype == UPIO_MEM)
+       if (port->iotype == UPIO_MEM || port->iotype == UPIO_DWAPB)
                writeb(value, port->membase + offset);
        else
                outb(value, port->iobase + offset);
@@ -233,7 +233,7 @@
                return 0;

        /* Try to start the normal driver on a matching line.  */
-       mmio = (port->iotype == UPIO_MEM);
+       mmio = (port->iotype == UPIO_MEM || port->iotype == UPIO_DWAPB);
        line = serial8250_start_console(port, device->options);
        if (line < 0)
                printk("No ttyS device at %s 0x%lx for console\n",
Index: linux_2_6/drivers/serial/serial_core.c
===================================================================
RCS file: linux_2_6/drivers/serial/serial_core.c,v
retrieving revision 1.1.1.7
diff -u -r1.1.1.7 serial_core.c
--- linux_2_6/drivers/serial/serial_core.c      19 Oct 2006 21:00:58 -0000      
1.1.1.7
+++ linux_2_6/drivers/serial/serial_core.c      24 Jan 2007 23:55:28 -0000
@@ -1669,9 +1669,10 @@

        ret = sprintf(buf, "%d: uart:%s %s%08lX irq:%d",
                        port->line, uart_type(port),
-                       port->iotype == UPIO_MEM ? "mmio:0x" : "port:",
-                       port->iotype == UPIO_MEM ? port->mapbase :
-                                               (unsigned long) port->iobase,
+                       (port->iotype == UPIO_MEM || port->iotype == UPIO_DWAPB)
+                               ? "mmio:0x" : "port:",
+                       (port->iotype == UPIO_MEM || port->iotype == UPIO_DWAPB)
+                               ? port->mapbase : (unsigned long) port->iobase,
                        port->irq);

        if (port->type == PORT_UNKNOWN) {
@@ -2037,6 +2038,7 @@
        case UPIO_MEM32:
        case UPIO_AU:
        case UPIO_TSI:
+       case UPIO_DWAPB:
                snprintf(address, sizeof(address),
                         "MMIO 0x%lx", port->mapbase);
                break;
@@ -2380,6 +2382,7 @@
        case UPIO_MEM32:
        case UPIO_AU:
        case UPIO_TSI:
+       case UPIO_DWAPB:
                return (port1->mapbase == port2->mapbase);
        }
        return 0;
Index: linux_2_6/include/linux/serial_core.h
===================================================================
RCS file: linux_2_6/include/linux/serial_core.h,v
retrieving revision 1.1.1.7
diff -u -r1.1.1.7 serial_core.h
--- linux_2_6/include/linux/serial_core.h       19 Oct 2006 21:01:02 -0000      
1.1.1.7
+++ linux_2_6/include/linux/serial_core.h       24 Jan 2007 23:55:28 -0000
@@ -228,6 +228,7 @@
  #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 */
@@ -258,6 +259,8 @@
  #define UPF_CONS_FLOW         ((__force upf_t) (1 << 23))
  #define UPF_SHARE_IRQ         ((__force upf_t) (1 << 24))
  #define UPF_BOOT_AUTOCONF     ((__force upf_t) (1 << 28))
+#define UPF_DW_THRE_BUG                ((__force upf_t)(1 << 29)) /* 
DesignWare THRE hardware BUG
+                                                                               
                                * (cannot be autodetected) */
  #define UPF_DEAD              ((__force upf_t) (1 << 30))
  #define UPF_IOREMAP           ((__force upf_t) (1 << 31))

@@ -274,6 +277,7 @@
        struct device           *dev;                   /* parent device */
        unsigned char           hub6;                   /* this should be in 
the 8250 driver */
        unsigned char           unused[3];
+       void                            *user;                  /* generic 
platform 'user' pointer */
  };

  /*
Index: linux_2_6/include/linux/serial_reg.h
===================================================================
RCS file: linux_2_6/include/linux/serial_reg.h,v
retrieving revision 1.1.1.2
diff -u -r1.1.1.2 serial_reg.h
--- linux_2_6/include/linux/serial_reg.h        19 Oct 2006 18:29:50 -0000      
1.1.1.2
+++ linux_2_6/include/linux/serial_reg.h        24 Jan 2007 23:55:29 -0000
@@ -218,6 +218,10 @@
  #define UART_FCR_PXAR16       0x80    /* receive FIFO treshold = 16 */
  #define UART_FCR_PXAR32       0xc0    /* receive FIFO treshold = 32 */

+/*
+ * DesignWare APB UART
+ */
+#define UART_IIR_BUSY          0x07    /* Busy Detect */




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