Re: [PATCH v5 2/3] serial: 8250: Add Loongson uart driver support

[Jiri Slaby <jirislaby@kernel.org>]

On 24. 09. 25, 8:29, Binbin Zhou wrote:
> Add the driver for on-chip UART used on Loongson family chips.
> 
> The hardware is similar to 8250, but there are the following
> differences:
>   - Some chips (such as Loongson-2K2000) have added a fractional division
>     register to obtain the required baud rate accurately, so the
>     {get,set}_divisor callback is overridden.
>   - Due to hardware defects, quirk handling is required for
>     UART_MCR/UART_MSR.

So how hard would be to implement this in 8250 using existing (or new) 
callbacks+quirks?

> --- /dev/null
> +++ b/drivers/tty/serial/8250/8250_loongson.c
> @@ -0,0 +1,202 @@
...
> +struct loongson_uart_data {
> +	int line;
> +	int mcr_invert;
> +	int msr_invert;

These two should be unsigned. They should be u8, actually.

> +	struct reset_control *rst;
> +};
> +
> +static unsigned int serial_fixup(struct uart_port *p, unsigned int offset, unsigned int val)

Both 'val' and ret type should be u8.

> +{
> +	struct loongson_uart_data *ddata = p->private_data;
> +
> +	if (offset == UART_MCR)
> +		val ^= ddata->mcr_invert;
> +
> +	if (offset == UART_MSR)
> +		val ^= ddata->msr_invert;
> +
> +	return val;
> +}
> +
> +static u32 loongson_serial_in(struct uart_port *p, unsigned int offset)
> +{
> +	unsigned int val;

u8

> +
> +	val = readb(p->membase + (offset << p->regshift));
> +
> +	return serial_fixup(p, offset, val);
> +}

thanks,
-- 
js
suse labs