Re: [PATCH v2 1/3] tty: Introduce UART_CAP_HW485

Matwey V. Kornilov
2015-11-07T12:40:14Z

2015-11-07 15:22 GMT+03:00 Peter Hurley <peter@hurleysoftware.com>:
> On 11/07/2015 05:09 AM, Matwey V. Kornilov wrote:
>> Introduce new capability UART_CAP_HW485 to mark 8250 UARTs which have
>> hardware support of line direction control.
>
> Since capabilities are not exported to user-space, how will user-space
> know if the port only provides emulated 485 (eg., where only HW485 is
> acceptable)?

I cannot imagine the case when user really has to care about
implementation details.
In both cases the user will be provided with the consistent API
(TIOCGRS485/TIOCSRS485 ioctls) resulting into the same behavior.
Could you please expand your question?

>
> Regards,
> Peter Hurley
>
>> Signed-off-by: Matwey V. Kornilov <matwey@sai.msu.ru>
>> ---
>> Changes since v1:
>> - Commit message has been wrapped
>>
>> drivers/tty/serial/8250/8250.h | 1 +
>> drivers/tty/serial/8250/8250_fintek.c | 1 +
>> drivers/tty/serial/8250/8250_lpc18xx.c | 1 +
>> drivers/tty/serial/8250/8250_pci.c | 1 +
>> 4 files changed, 4 insertions(+)
>>
>> diff --git a/drivers/tty/serial/8250/8250.h b/drivers/tty/serial/8250/8250.h
>> index d54dcd8..92a4f47 100644
>> --- a/drivers/tty/serial/8250/8250.h
>> +++ b/drivers/tty/serial/8250/8250.h
>> @@ -69,6 +69,7 @@ struct serial8250_config {
>> unsigned int flags;
>> };
>>
>> +#define UART_CAP_HW485 (1 << 7) /* UART has hardware direction control for RS485 */
>> #define UART_CAP_FIFO (1 << 8) /* UART has FIFO */
>> #define UART_CAP_EFR (1 << 9) /* UART has EFR */
>> #define UART_CAP_SLEEP (1 << 10) /* UART has IER sleep */
>> diff --git a/drivers/tty/serial/8250/8250_fintek.c b/drivers/tty/serial/8250/8250_fintek.c
>> index 8947439..f2831a8 100644
>> --- a/drivers/tty/serial/8250/8250_fintek.c
>> +++ b/drivers/tty/serial/8250/8250_fintek.c
>> @@ -208,6 +208,7 @@ fintek_8250_probe(struct pnp_dev *dev, const struct pnp_device_id *dev_id)
>> uart.port.iobase = pnp_port_start(dev, 0);
>> uart.port.iotype = UPIO_PORT;
>> uart.port.rs485_config = fintek_8250_rs485_config;
>> + uart.capabilities = UART_CAP_HW485;
>>
>> uart.port.flags |= UPF_SKIP_TEST | UPF_BOOT_AUTOCONF;
>> if (pnp_irq_flags(dev, 0) & IORESOURCE_IRQ_SHAREABLE)
>> diff --git a/drivers/tty/serial/8250/8250_lpc18xx.c b/drivers/tty/serial/8250/8250_lpc18xx.c
>> index 99cd478..9d30276 100644
>> --- a/drivers/tty/serial/8250/8250_lpc18xx.c
>> +++ b/drivers/tty/serial/8250/8250_lpc18xx.c
>> @@ -175,6 +175,7 @@ static int lpc18xx_serial_probe(struct platform_device *pdev)
>> uart.port.private_data = data;
>> uart.port.rs485_config = lpc18xx_rs485_config;
>> uart.port.serial_out = lpc18xx_uart_serial_out;
>> + uart.capabilities = UART_CAP_HW485;
>>
>> uart.dma = &data->dma;
>> uart.dma->rxconf.src_maxburst = 1;
>> diff --git a/drivers/tty/serial/8250/8250_pci.c b/drivers/tty/serial/8250/8250_pci.c
>> index 4097f3f..c7c0ae9 100644
>> --- a/drivers/tty/serial/8250/8250_pci.c
>> +++ b/drivers/tty/serial/8250/8250_pci.c
>> @@ -1599,6 +1599,7 @@ static int pci_fintek_setup(struct serial_private *priv,
>> port->port.iotype = UPIO_PORT;
>> port->port.iobase = iobase;
>> port->port.rs485_config = pci_fintek_rs485_config;
>> + port->capabilities = UART_CAP_HW485;
>>
>> data = devm_kzalloc(&pdev->dev, sizeof(u8), GFP_KERNEL);
>> if (!data)
>>
>

--
With best regards,
Matwey V. Kornilov.
Sternberg Astronomical Institute, Lomonosov Moscow State University, Russia
119991, Moscow, Universitetsky pr-k 13, +7 (495) 9392382