Hello.
Marc St-Jean wrote:
Fourth 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 "mm" patch.
2. Fix for Busy Detect on LCR write
- Changed the ordering of test in serial8250_interrupt().
- Combined test for UPIO_DWAPB with UPIO_MEM in serial8250_start_console().
- Renamed new uart_8250_port member to private_data.
3. Workaround for interrupt/data concurrency issue
- No changes since last patch.
diff --git a/drivers/serial/8250.c b/drivers/serial/8250.c
index 3d91bfc..b309c4c 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 (up->port.iotype == UPIO_DWAPB &&
+ (iir & UART_IIR_BUSY) == UART_IIR_BUSY) {
Worth aligning this line with the opening paren of if... but's that's
nitpicking. :-)
+ /* 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;
return 0;
Still, shouldn't you be doing this in serial8250_timeout() also?
What IRQ numbers this UART is using, BTW?
diff --git a/include/linux/serial_core.h b/include/linux/serial_core.h
index cf23813..bd9711a 100644
--- a/include/linux/serial_core.h
+++ b/include/linux/serial_core.h
@@ -276,6 +277,7 @@ #define UPF_USR_MASK ((__force upf_t) (
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 */
One tab to many before *private_data...
diff --git a/include/linux/serial_reg.h b/include/linux/serial_reg.h
index 3c8a6aa..1c5ed7d 100644
--- a/include/linux/serial_reg.h
+++ b/include/linux/serial_reg.h
@@ -38,6 +38,8 @@ #define UART_IIR_THRI 0x02 /* Transmitt
#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 */
Oops, your mailer went and did it again. :-)
WBR, Sergei
