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