Marc St-Jean wrote:
Third attempt at the serial driver patch for the PMC-Sierra MSP71xx device.
There are three different fixes:
1. Fix for DesignWare THRE errata
- Dropped our fix since the "8250-uart-backup-timer.patch" in the "mm"
tree also fixes it. This patch needs to be applied on top of it.
2. Fix for Busy Detect on LCR write
- Dropped the addition of UPIO_DWAPB iotype to 8250_early.c as Sergei
pointed out the fix wasn't complete and we don't require it.
3. Workaround for interrupt/data concurrency issue
- Fix must remain serial8250_interrupt() in order to mark interrupt as
handled.
Thanks,
Marc
Signed-off-by: Marc St-Jean <Marc_St-Jean@xxxxxxxxxxxxxx>
diff --git a/drivers/serial/8250.c b/drivers/serial/8250.c
index 3d91bfc..489ff2b 100644
--- a/drivers/serial/8250.c
+++ b/drivers/serial/8250.c
@@ -308,6 +308,7 @@ static unsigned int serial_in(struct uar
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 @@ #endif
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 @@ #endif
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);
}
@@ -373,6 +388,7 @@ serial_out_sync(struct uart_8250_port *u
#ifdef CONFIG_SERIAL_8250_AU1X00
case UPIO_AU:
#endif
+ case UPIO_DWAPB:
serial_out(up, offset, value);
(void)serial_in(up, UART_LCR); /* safe, no side-effects */
break;
@@ -1383,6 +1399,19 @@ static irqreturn_t serial8250_interrupt(
handled = 1;
end = NULL;
+ } else if ((iir & UART_IIR_BUSY) == UART_IIR_BUSY &&
+ up->port.iotype == UPIO_DWAPB) {
Makes sense to swap the checks, i.e. to only test for UART_IIR_BUSY is
this is UPIO_DWAPB.
+ /* 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.data;
+ serial_out(up, UART_LCR, up->lcr);
+
+ handled = 1;
+
+ end = NULL;
} else if (end == NULL)
end = l;
[...]
@@ -2454,9 +2485,12 @@ int __init serial8250_start_console(stru
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);
Please turn this check into port->iotype >= UPIO_MEM, since this would be
the Right Thing (RM). All iotypes beyond UPIO_MEM are memory mapped. And I
thought I fixed that -- was wrong, obviously... :-/
diff --git a/include/linux/serial_reg.h b/include/linux/serial_reg.h
index 3c8a6aa..b3550cc 100644
--- a/include/linux/serial_reg.h
+++ b/include/linux/serial_reg.h
@@ -37,6 +37,7 @@ #define UART_IIR_MSI 0x00 /* Modem stat
#define UART_IIR_THRI 0x02 /* Transmitter holding register empty */
#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 */
Alan already said about this one... :-)
BTW, your patches are still corrupt by your mailer (space added to lines
starting with space)
MBR, Sergei
