[PATCH linux dev-4.13] serial: 8250: Add Nuvoton NPCM UART

[Tomer Maimon]

On 6 February 2018 at 12:37, Avi Fishman <avifishman70 at gmail.com> wrote:
> On Tue, Feb 6, 2018 at 7:50 AM, Joel Stanley <joel at jms.id.au> wrote:
>> On Mon, Feb 5, 2018 at 7:39 PM, Tomer Maimon <tmaimon77 at gmail.com> wrote:
>>> On 2 February 2018 at 06:27, Joel Stanley <joel at jms.id.au> wrote:
>>
>>>>  /* Uart divisor latch read */
>>>> @@ -2143,6 +2153,15 @@ int serial8250_do_startup(struct uart_port *port)
>>>>                                 UART_DA830_PWREMU_MGMT_FREE);
>>>>         }
>>>>
>>>> +       if (port->type == PORT_NPCM) {
>>>> +               /*
>>>> +                * Nuvoton calls the scratch register 'UART_TOR' (timeout
>>>> +                * register). Enable it, and set TIOC (timeout interrupt
>>>> +                * comparator) to be 0x20 for correct operation.
>>>> +                */
>>>> +               serial_port_out(port, UART_NPCM_TOR, UART_NPCM_TOIE | 0x20);
>>>> +       }
>>>
>>> Can we set the TOR register dynamically (adding special IOCTL)?
>>
>> We would have to have a good reason to do so.
>>
>> Under what circumstances would a user need to change this dynamically?
>
> Tomer, I agree it is not important to change at run time.
I agree Avi,
but the only problem I see with it that if we will need in the future
to TOR register dynamically (new SOC, client demand, etc.)
Could it be done in the 8250 files?
>
>>
>>>
>>>> +
>>>>  #ifdef CONFIG_SERIAL_8250_RSA
>>>>         /*
>>>>          * If this is an RSA port, see if we can kick it up to the
>>>> @@ -2465,6 +2484,15 @@ static unsigned int xr17v35x_get_divisor(struct uart_8250_port *up,
>>>>         return quot_16 >> 4;
>>>>  }
>>>>
>>>> +/* Nuvoton NPCM UARTs have a custom divisor calculation */
>>>> +static unsigned int npcm_get_divisor(struct uart_8250_port *up,
>>>> +               unsigned int baud)
>>>> +{
>>>> +       struct uart_port *port = &up->port;
>>>> +
>>>> +       return DIV_ROUND_CLOSEST(port->uartclk, 16 * baud + 2) - 2;
>>>> +}
>>
>> Did you test this version of the driver on your hardware?
Yes Thanks!!! it working fine.
>>
>> I think I understand why you had the extra code, but does it affect
>> operation in any of your tests?
>>
>> From what I understand the baud rates are often calculated to be "near enough".
>
> Joel, I made the original calculation but I agree that this one is
> good enough (I confused Tomer to think that your calculation will not
> fit :)
>
I see you add the TOR to include/uapi/linux/serial_reg.h will the
maintainer accept it?

>>
>> Cheers,
>>
>> Joel

Cheers,

Tomer