[PATCH RFC 4/9] serial: serial_meson: add minimal non-DM driver

[Heinrich Schuchardt]

On 9/10/25 22:14, Ferass El Hafidi wrote:
> On Wed Sep 10, 2025 at 7:53 PM UTC, Heinrich Schuchardt wrote:
>> <...>
>>> +static int meson_serial_getc(void)
>>> +{
>>> +	struct meson_uart *const uart = (struct meson_uart *)CONFIG_VAL(DEBUG_UART_BASE);
>>> +	uint32_t status = readl(&uart->status);
>>> +
>>> +	if (status & AML_UART_RX_EMPTY)
>>> +		return -EAGAIN;
>>> +
>>> +	if (status & AML_UART_ERR) {
>>> +		u32 val = readl(&uart->control);
>>> +
>>> +		/* Clear error */
>>> +		val |= AML_UART_CLR_ERR;
>>> +		writel(val, &uart->control);
>>> +		val &= ~AML_UART_CLR_ERR;
>>> +		writel(val, &uart->control);
>>> +
>>> +		/* Remove spurious byte from fifo */
>>> +		readl(&uart->rfifo);
>>> +		return -EIO;
>>> +	}
>>> +
>>> +	return readl(&uart->rfifo) & 0xff;
>>> +}
>>> +
>>> +static int meson_serial_tstc(void)
>>> +{
>>> +	struct meson_uart *const uart = (struct meson_uart *)CONFIG_VAL(DEBUG_UART_BASE);
>>
>> CONFIG_SPL_DEBUG_UART_BASE only exists for CONFIG_DEBUG_UART=y and
>> CONFIG_SPL=y. Shall all configurations depend on CONFIG_DEBUG_UART=y?
>>
>> Creating this dependency does not look right to me.
>>
> 
> All Amlogic defconfigs have CONFIG_DEBUG_UART enabled, but I can remove
> the dependency on CONFIG_DEBUG_UART_BASE if you think it doesn't look
> right.

We should avoid the possibility of build failures for changed configuration.

Will CONFIG_MESON_SERIAL depend on CONFIG_DEBUG_UART
or will CONFIG_ARCH_MESON select CONFIG_DEBUG_UART?

Best regards

Heinrich