2022-11-24 13:44:16

by Ilpo Järvinen

Subject: [PATCH 4/6] serial: 8250: Add IIR FIFOs enabled field properly

Don't use magic literals & comments but define a real field instead
for UART_IIR_FIFO_ENABLED and name also the values.

Signed-off-by: Ilpo Järvinen <[email protected]>
---
drivers/tty/serial/8250/8250_port.c | 17 +++++++----------
include/uapi/linux/serial_reg.h | 4 ++++
2 files changed, 11 insertions(+), 10 deletions(-)

diff --git a/drivers/tty/serial/8250/8250_port.c b/drivers/tty/serial/8250/8250_port.c
index e79bf2afd9be..6d343b15bc58 100644
--- a/drivers/tty/serial/8250/8250_port.c
+++ b/drivers/tty/serial/8250/8250_port.c
@@ -1293,22 +1293,19 @@ static void autoconfig(struct uart_8250_port *up)

serial_out(up, UART_FCR, UART_FCR_ENABLE_FIFO);

- /* Assign this as it is to truncate any bits above 7. */
- scratch = serial_in(up, UART_IIR);
-
- switch (scratch >> 6) {
- case 0:
+ switch (serial_in(up, UART_IIR) & UART_IIR_FIFO_ENABLED) {
+ case UART_IIR_FIFO_ENABLED_8250:
autoconfig_8250(up);
break;
- case 1:
- port->type = PORT_UNKNOWN;
- break;
- case 2:
+ case UART_IIR_FIFO_EAABLED_16550:
port->type = PORT_16550;
break;
- case 3:
+ case UART_IIR_FIFO_ENABLED_16550A:
autoconfig_16550a(up);
break;
+ default:
+ port->type = PORT_UNKNOWN;
+ break;
}

#ifdef CONFIG_SERIAL_8250_RSA
diff --git a/include/uapi/linux/serial_reg.h b/include/uapi/linux/serial_reg.h
index bab3b39266cc..a63c124b7fdc 100644
--- a/include/uapi/linux/serial_reg.h
+++ b/include/uapi/linux/serial_reg.h
@@ -44,6 +44,10 @@
#define UART_IIR_RX_TIMEOUT 0x0c /* OMAP RX Timeout interrupt */
#define UART_IIR_XOFF 0x10 /* OMAP XOFF/Special Character */
#define UART_IIR_CTS_RTS_DSR 0x20 /* OMAP CTS/RTS/DSR Change */
+#define UART_IIR_FIFO_ENABLED 0xc0 /* FIFOs enabled / port type identification */
+#define UART_IIR_FIFO_ENABLED_8250 0x00 /* 8250: no FIFO */
+#define UART_IIR_FIFO_EAABLED_16550 0x80 /* 16550: (broken/unusable) FIFO */
+#define UART_IIR_FIFO_ENABLED_16550A 0xc0 /* 16550A: FIFO enabled */

#define UART_FCR 2 /* Out: FIFO Control Register */
#define UART_FCR_ENABLE_FIFO 0x01 /* Enable the FIFO */
--
2.30.2

2022-11-25 12:00:26

by Jiri Slaby

Subject: Re: [PATCH 4/6] serial: 8250: Add IIR FIFOs enabled field properly

On 24. 11. 22, 13:59, Ilpo Järvinen wrote:
> Don't use magic literals & comments but define a real field instead
> for UART_IIR_FIFO_ENABLED and name also the values.
>
> Signed-off-by: Ilpo Järvinen <[email protected]>
> ---
> drivers/tty/serial/8250/8250_port.c | 17 +++++++----------
> include/uapi/linux/serial_reg.h | 4 ++++
> 2 files changed, 11 insertions(+), 10 deletions(-)
>
> diff --git a/drivers/tty/serial/8250/8250_port.c b/drivers/tty/serial/8250/8250_port.c
> index e79bf2afd9be..6d343b15bc58 100644
> --- a/drivers/tty/serial/8250/8250_port.c
> +++ b/drivers/tty/serial/8250/8250_port.c
> @@ -1293,22 +1293,19 @@ static void autoconfig(struct uart_8250_port *up)
>
> serial_out(up, UART_FCR, UART_FCR_ENABLE_FIFO);
>
> - /* Assign this as it is to truncate any bits above 7. */
> - scratch = serial_in(up, UART_IIR);
> -
> - switch (scratch >> 6) {
> - case 0:
> + switch (serial_in(up, UART_IIR) & UART_IIR_FIFO_ENABLED) {
> + case UART_IIR_FIFO_ENABLED_8250:
> autoconfig_8250(up);
> break;
> - case 1:
> - port->type = PORT_UNKNOWN;
> - break;
> - case 2:
> + case UART_IIR_FIFO_EAABLED_16550:

EAABLED :)?

> --- a/include/uapi/linux/serial_reg.h
> +++ b/include/uapi/linux/serial_reg.h
> @@ -44,6 +44,10 @@
> #define UART_IIR_RX_TIMEOUT 0x0c /* OMAP RX Timeout interrupt */
> #define UART_IIR_XOFF 0x10 /* OMAP XOFF/Special Character */
> #define UART_IIR_CTS_RTS_DSR 0x20 /* OMAP CTS/RTS/DSR Change */
> +#define UART_IIR_FIFO_ENABLED 0xc0 /* FIFOs enabled / port type identification */
> +#define UART_IIR_FIFO_ENABLED_8250 0x00 /* 8250: no FIFO */
> +#define UART_IIR_FIFO_EAABLED_16550 0x80 /* 16550: (broken/unusable) FIFO */
> +#define UART_IIR_FIFO_ENABLED_16550A 0xc0 /* 16550A: FIFO enabled */
>
> #define UART_FCR 2 /* Out: FIFO Control Register */
> #define UART_FCR_ENABLE_FIFO 0x01 /* Enable the FIFO */

--
js
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