linux-kernel - Re: [PATCH] serial: 8250: Add Nuvoton NPCM UART

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Date:   Thu, 15 Feb 2018 12:30:02 +1030
From:   Joel Stanley <joel@....id.au>
To:     Andy Shevchenko <andy.shevchenko@...il.com>
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        linux-serial@...r.kernel.org,
        devicetree <devicetree@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Tomer Maimon <tomer.maimon@...oton.com>,
        Avi Fishman <Avi.Fishman@...oton.com>,
        Jeremy Kerr <jk@...abs.org>
Subject: Re: [PATCH] serial: 8250: Add Nuvoton NPCM UART

On Wed, Feb 14, 2018 at 3:22 AM, Andy Shevchenko
<andy.shevchenko@...il.com> wrote:
> On Mon, Feb 12, 2018 at 6:48 AM, Joel Stanley <joel@....id.au> wrote:
>> The Nuvoton UART is almost compatible with the 8250 driver when probed
>> via the 8250_of driver, however it requires some extra configuration
>> at startup.
>
>
>> +       [PORT_NPCM] = {
>> +               .name           = "Nuvoton 16550",
>> +               .fifo_size      = 16,
>> +               .tx_loadsz      = 16,
>> +               .fcr            = UART_FCR_ENABLE_FIFO | UART_FCR_R_TRIG_10 |
>> +                                 UART_FCR_CLEAR_RCVR | UART_FCR_CLEAR_XMIT,
>> +               .rxtrig_bytes   = {1, 4, 8, 14},
>> +               .flags          = UART_CAP_FIFO,
>
>> +
>
> Redundant.

You are referring to the extra whitespace?

>> +       },
>
>> +               /*
>> +                * 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);
>
>> +/* Nuvoton NPCM UARTs have a custom divisor calculation */
>> +       return DIV_ROUND_CLOSEST(port->uartclk, 16 * baud + 2) - 2;
>
> Is there any link to datasheet?

I have a copy of the datasheet under NDA. The Nuvoton guys might be
able to help you out. Avi?

>
>> +/* Nuvoton UART */
>> +#define PORT_NPCM      118
>
> We have gaps there. #40 is perfect place for this one.

Ok, I will move it up. Thanks for the review.

Cheers,

Joel