Re: [PATCH v5 05/28] efi: serial: Support arrow keys

[Heinrich Schuchardt <xypron.glpk@gmx.de>]

On 12/17/21 17:37, Simon Glass wrote:
> Hi Heinrich,
>
> On Thu, 9 Dec 2021 at 12:44, Heinrich Schuchardt <xypron.glpk@gmx.de> wrote:
>>
>> On 12/4/21 07:56, Simon Glass wrote:
>>> At present only the backspace key is supported in U-Boot, when running as
>>> an EFI app. Add support for arrows, home and end as well, to make the CLI
>>> more friendly.
>>>
>>> Signed-off-by: Simon Glass <sjg@chromium.org>
>>> ---
>>>
>>> (no changes since v1)
>>>
>>>    drivers/serial/serial_efi.c | 11 +++++++++--
>>>    1 file changed, 9 insertions(+), 2 deletions(-)
>>>
>>> diff --git a/drivers/serial/serial_efi.c b/drivers/serial/serial_efi.c
>>> index 33ddbd6080c..0067576389d 100644
>>> --- a/drivers/serial/serial_efi.c
>>> +++ b/drivers/serial/serial_efi.c
>>> @@ -24,6 +24,9 @@ struct serial_efi_priv {
>>>        bool have_key;
>>>    };
>>>
>>> +/* Convert a lower-case character to its ctrl-char equivalent */
>>> +#define CTL_CH(c)            ((c) - 'a' + 1)
>>> +
>>>    int serial_efi_setbrg(struct udevice *dev, int baudrate)
>>>    {
>>>        return 0;
>>> @@ -49,6 +52,7 @@ static int serial_efi_get_key(struct serial_efi_priv *priv)
>>>    static int serial_efi_getc(struct udevice *dev)
>>>    {
>>>        struct serial_efi_priv *priv = dev_get_priv(dev);
>>> +     char conv_scan[10] = {0, 'p', 'n', 'f', 'b', 'a', 'e', 0, 8};
>>>        int ret, ch;
>>>
>>>        ret = serial_efi_get_key(priv);
>>> @@ -63,8 +67,11 @@ static int serial_efi_getc(struct udevice *dev)
>>>         * key scan code of 8. Handle this so that backspace works correctly
>>>         * in the U-Boot command line.
>>>         */
>>> -     if (!ch && priv->key.scan_code == 8)
>>> -             ch = 8;
>>> +     if (!ch && priv->key.scan_code < sizeof(conv_scan)) {
>>> +             ch = conv_scan[priv->key.scan_code];
>>> +             if (ch >= 'a')
>>> +                     ch -= 'a' - 1;
>>
>> This is not what a serial console would use in Linux. Just try U-Boot's
>> conitrace command. If you use the following, we get compatibility with
>> the rest of U-Boot:
>>
>> 1b 5b 32 7e - insert
>> 1b 5b 33 7e - delete
>> 1b 5b 35 7e - page up
>> 1b 5b 36 7e - page down
>> 1b 5b 41 - up
>> 1b 5b 42 - down
>> 1b 5b 43 - right
>> 1b 5b 44 - left
>> 1b 5b 46 - end
>> 1b 5b 48 - home
>
> That's more complicated since it requires the serial driver to convert
> one character into multiple. We can always add it later if needed. But
> this does command-line history, etc. working in the app.

Yes you will need a ring buffer as in the USB keyboard driver.

lib/efi_loader/efi_console.c only understands the multi-byte sequences.
I do not know if there are other places which have the same limitation.

Best regards

Heinrich

>
> Regards,
> Simon