mmc: sdio add regulator vsdio

[zhangfei gao]

>>+
>>+static int __init brownstone_init_mmc(void)
>>+{
>>+      /*
>>+       * PDn: GPIO58; RESETn: GPIO57
>>+       * 8787, RESETn keeps high, PDn control power
>>+       * on: PDn 1; off: PDn 0;
>>+       */
>
> Comment unclear
>
> GPIO57 is power
> GPIO58 is reset

yes, typo, thanks
>
>
>
>>+      int RESETn = mfp_to_gpio(MFP_PIN_GPIO58);
>>+
>>+      if (gpio_request(RESETn, "sdio RESETn")) {
>>+              pr_err("Failed to request sdio RESETn gpio\n");
>>+              return -EIO;
>>+      }
>>+      gpio_direction_output(RESETn, 1);
>>+      gpio_free(RESETn);
>
>
> The 8787  data sheet indicated that PDn should be inactive as well as reset before
> initiating power up.
>
> Pull PDn high.

The PDn is super-set of RESETn, keep RESETn high, and control 8787
with PDn is enough.
The "Internal Reset" in data sheet is not RESET pin.