Re: [PATCH v2 5/6] gpio-exar/8250-exar: Make set of exported GPIOs configurable

From: Andy Shevchenko
Date: Thu May 18 2017 - 13:43:49 EST


On Thu, May 18, 2017 at 5:59 PM, Jan Kiszka <jan.kiszka@xxxxxxxxxxx> wrote:
> On the SIMATIC, IOT2040 only a single pin is exportable as GPIO, the
> rest is required to operate the UART. To allow modeling this case,
> expand the platform device data structure to specify a (consecutive) pin
> subset for exporting by the gpio-exar driver.

> + unsigned int first_gpio;

Perhaps pin?
Or shift?

Because first_gpio a bit confusing with Linux side of GPIO.

> - unsigned int bank = offset / 8;
> - unsigned int addr;
> + struct exar_gpio_chip *exar_gpio = gpiochip_get_data(chip);
> + unsigned int bank, addr;
>
> + offset += exar_gpio->first_gpio;
> + bank = offset / 8;

Can't we instead do something like the following:

struct exar_gpio_chip *exar_gpio = gpiochip_get_data(chip);
unsigned int bank = (offset + exar_gpio->pin) / 8;
unsigned int line = (offset + exar_gpio->pin) % 8;


> + pdata.first_gpio = first_gpio;
> + pdata.ngpio = ngpio;

Still thinking about device properties ("ngpios" and something like
"exar8250,gpio-start").

> + unsigned int first_gpio;
> + unsigned int ngpio;

u16 ?

--
With Best Regards,
Andy Shevchenko