Re: [PATCH 40/41] drivers: tty: serial: helper for setting mmio range

Andy Shevchenko
2019-04-28T15:39:17Z

On Sat, Apr 27, 2019 at 02:52:21PM +0200, Enrico Weigelt, metux IT consult wrote:
> Introduce a little helpers for settings the mmio range from an
> struct resource or start/len parameters with less code.
> (also setting iotype to UPIO_MEM)
>
> Also converting drivers to use these new helpers as well as
> fetching mapsize field instead of using hardcoded values.
> (the runtime overhead of that should be negligible)
>
> The idea is moving to a consistent scheme, so later common
> calls like request+ioremap combination can be done by generic
> helpers.

> --- a/drivers/tty/serial/8250/8250_exar.c
> +++ b/drivers/tty/serial/8250/8250_exar.c
> @@ -134,8 +134,10 @@ static int default_setup(struct exar8250 *priv, struct pci_dev *pcidev,
> const struct exar8250_board *board = priv->board;
> unsigned int bar = 0;
>
> - port->port.iotype = UPIO_MEM;
> - port->port.mapbase = pci_resource_start(pcidev, bar) + offset;
> + uart_memres_set_start_len(&port->port,
> + pci_resource_start(pcidev, bar) + offset,
> + pci_resource_len(pcidev, bar));
> +

I don't see how it's better.
Moreover, the size argument seems wrong here.

> + uart_memres_set_start_len(
> + &port,
> + FRODO_BASE + FRODO_APCI_OFFSET(1), 0);

Please, avoid such splitting, first parameter is quite fit above line.

> port.uartclk = HPDCA_BAUD_BASE * 16;
> - port.mapbase = (pa + UART_OFFSET);
> +
> + uart_memres_set_start_len(&port, (pa + UART_OFFSET));
> port.membase = (char *)(port.mapbase + DIO_VIRADDRBASE);
> port.regshift = 1;
> port.irq = DIO_IPL(pa + DIO_VIRADDRBASE);

Here...

> uart.port.flags = UPF_SKIP_TEST | UPF_SHARE_IRQ | UPF_BOOT_AUTOCONF;
> uart.port.irq = d->ipl;
> uart.port.uartclk = HPDCA_BAUD_BASE * 16;
> - uart.port.mapbase = (d->resource.start + UART_OFFSET);
> + uart_memres_set_start_len(&uart.port,
> + (d->resource.start + UART_OFFSET),
> + resource_size(&d->resource));
> uart.port.membase = (char *)(uart.port.mapbase + DIO_VIRADDRBASE);
> uart.port.regshift = 1;
> uart.port.dev = &d->dev;

...and here, and maybe in other places you split the assignments to the members
in two part. Better to call your function before or after these blocks of
assignments.

> - uport->mapsize = ZS_CHAN_IO_SIZE;
> - uport->mapbase = dec_kn_slot_base +
> - zs_parms.scc[chip] +
> - (side ^ ZS_CHAN_B) * ZS_CHAN_IO_SIZE;
> +
> + uart_memres_set_start_len(dec_kn_slot_base +
> + zs_parms.scc[chip] +
> + (side ^ ZS_CHAN_B) *
> + ZS_CHAN_IO_SIZE,
> + ZS_CHAN_IO_SIZE);

This looks hard to read. Think of temporary variables and better formatting
style.

> /*
> + * set physical io range from struct resource
> + * if resource is NULL, clear the fields
> + * also set the iotype to UPIO_MEM

Something wrong with punctuation and style. Please, use proper casing and
sentences split.

> + */

Shouldn't be kernel-doc formatted?

> +static inline void uart_memres_set_res(struct uart_port *port,

Perhaps better name can be found.
Especially taking into account that it handles IO / MMIO here.

> + struct resource *res)
> +{
> + if (!res) {

It should return an error in such case.

> + port->mapsize = 0;
> + port->mapbase = 0;
> + port->iobase = 0;
> + return;
> + }
> +
> + if (resource_type(res) == IORESOURCE_IO) {
> + port->iotype = UPIO_PORT;
> + port->iobase = resource->start;
> + return;
> + }
> +
> + uart->mapbase = res->start;
> + uart->mapsize = resource_size(res);

> + uart->iotype = UPIO_MEM;

Only one type? Why type is even set here?

> +}
> +
> +/*
> + * set physical io range by start address and length
> + * if resource is NULL, clear the fields
> + * also set the iotype to UPIO_MEM

Should be fixed as told above.

> + */

> +static inline void uart_memres_set_start_len(struct uart_driver *uart,
> + resource_size_t start,
> + resource_size_t len)

The comment doesn't tell why this is needed when we have one for struct
resource.

> +{
> + uart->mapbase = start;
> + uart->mapsize = len;

> + uart->iotype = UPIO_MEM;

Only one type?

> +}
> +
> +/*

--
With Best Regards,
Andy Shevchenko