Re: [PATCH] serial driver PMC MSP71xx, kernel linux-mips.git master
From: Sergei Shtylyov
Date: Thu Jan 25 2007 - 09:51:01 EST
Marc St-Jean wrote:
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.
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
[...]
@@ -333,6 +334,8 @@
static void
serial_out(struct uart_8250_port *up, int offset, int value)
Your patch is clearly garbled again, something added an extra space to all
lines stating with space... :-/
{
+ /* Save the offset before it's remapped */
+ int save_offset = offset;
Is there real need to save this? What regshift equals for this UART?
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) &&
Not sure how an IER read ensures that...
+ in_irq())
I'd suggest to either indent this line right (start below 2ns paren of if
stmt) or keep on the same line.
+ 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)
Why read IIR if you don't check it?
@@ -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_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",
From your 8250_eraly.c changes I can conclude regshift == 1 (it doesn't
currently support other cases). So, serial_pot() doesn't need save_offset. :-)
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) {
Needless change. My patch that fixes this function is in Linus' tree since
September, not sure why you don't have it:
http://www2.kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=6c6a2334a1e8af7c3eaab992732825fa9ade77cf
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
[...]
@@ -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 */
Erm, 'private' or 'data' would've sounded better in the kernel context,
IMHO... :-)
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 */
I'd suggest keeping this with other UART_IIR_* #defines, separated by the
more elaborate comment.
WBR, Sergei
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/