Re: [rtc-linux] [PATCH 8/8] ARM: vt8500: gpio: Devicetree support for arch-vt8500

Linus Walleij
2012-08-08T09:11:53Z

On Wed, Aug 8, 2012 at 3:39 AM, Tony Prisk <linux@prisktech.co.nz> wrote:

> Converted the existing arch-vt8500 gpio to a platform_device.
> Added support for WM8505 and WM8650 GPIO controllers.
(...)
> +++ b/drivers/gpio/gpio-vt8500.c

This driver looks very one-bit-per-gpio typed. Are you sure you cannot
just reuse drivers/gpio/gpio-generic.c? Make a compelling case please...

> +struct vt8500_gpio_bank_regs {
> + int en;
> + int dir;
> + int data_out;
> + int data_in;

Why are all these members int? They should be u8 from reading your code.

> + int ngpio;
> +};

> +static struct vt8500_gpio_data vt8500_data = {
> + .num_banks = 7,
> + .banks = {
> + VT8500_BANK(0x00, 0x20, 0x40, 0x60, 26),
> + VT8500_BANK(0x04, 0x24, 0x44, 0x64, 28),
> + VT8500_BANK(0x08, 0x28, 0x48, 0x68, 31),
> + VT8500_BANK(0x0C, 0x2C, 0x4C, 0x6C, 19),
> + VT8500_BANK(0x10, 0x30, 0x50, 0x70, 19),
> + VT8500_BANK(0x14, 0x34, 0x54, 0x74, 23),
> + VT8500_BANK(-1, 0x3C, 0x5C, 0x7C, 9), /* external gpio */

What on earth are all those magic numbers?

I *guess* they're enabling some default GPIO settings etc.

But it really needs better structure, #defines for each one or
atleast include <linux/bitops.h> and say:

= BIT(4) | /* Enable GPIO pin 5 on this bank */
BIT(5); /* Enable GPIO pin 6 on this bank */

However I suspect this is board specific and should
be taken from device tree. Please elaborate on this...

Ditto for the different instances.

(...)
> + unsigned val;

Looks like all of these should be u8.

> + val = readl(vt8500_chip->base + vt8500_chip->regs->en +
> + vt8500_chip->regoff);

val = (u8) readl(...);

usw

> + val |= (1 << offset);

Use <linux/bitops.h>

val |= BIT(offset);

Apart from these remarks it's looking good...

Yours,
Linus Walleij