tree 8c8d8a1f441f9989b21a7e8a61151b2926bfbe79
parent ace6a9aef37b0cbef0da1072e6b2831f671af4b0
author Mike Voydanoff <voydanoff@google.com> 1537366204 -0700
committer Mike Voydanoff <voydanoff@google.com> 1537386664 +0000

[gpio] Refactor the GPIO protocol

This is a first step in a move toward using protocols to represent
individual resources. A similar change will be made to the I2C protocol
to bring it in line with how I2C is used on x86 platforms.

From the client's point of view, an instance of the ZX_PROTOCOL_GPIO
protocol now represents a single pin. The protocol remains the same,
except the "uint32_t index" has been removed from all the protocol functions.

For devices that have only one GPIO resource assigned to them, the driver
can simply call device_get_protocol() to access the GPIO protocol for the pin.
To for devices with more than one GPIO pins, a new API in the platform bus called
pdev_get_protocol() must be used instead.

In addition, we add a new protocol ZX_PROTOCOL_GPIO_IMPL, which is now
implemented by the GPIO drivers. This protocol is essentially the same as
the old GPIO protocol, except "index" has been renamed "pin".
Board drivers may use this protocol directly when doing low level system
configuration, specifying pin numbers directly.

TEST: Booted on VIM2 and Hikey.
On VIM2, USB, display, ethernet and the GPIO test driver are working properly
On Hikey, the system boots and USB is functional.

Change-Id: I44f1bc11ad9793543361a2d19d7a2de4458c334b