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Add a reset driver framework/uclass

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A reset controller is a hardware module that controls reset signals that
affect other hardware modules or chips.

This patch defines a standard API that connects reset clients (i.e. the
drivers for devices affected by reset signals) to drivers for reset
controllers/providers. Initially, DT is the only supported method for
connecting the two.

The DT binding specification (reset.txt) was taken from Linux kernel
v4.5's Documentation/devicetree/bindings/reset/reset.txt.

Signed-off-by: Stephen Warren <swarren@nvidia.com>
Acked-by: Simon Glass <sjg@chromium.org>
This commit is contained in:
Stephen Warren 2016-06-17 09:43:58 -06:00 • committed by Simon Glass
parent 0f67e2395b
commit 89c1e2da78
9 changed files with 446 additions and 0 deletions
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/*
* Copyright (c) 2016, NVIDIA CORPORATION.
*
* SPDX-License-Identifier: GPL-2.0
*/
#ifndef _RESET_UCLASS_H
#define _RESET_UCLASS_H
/* See reset.h for background documentation. */
#include <reset.h>
struct udevice;
/**
* struct reset_ops - The functions that a reset controller driver must
* implement.
*/
struct reset_ops {
/**
* of_xlate - Translate a client's device-tree (OF) reset specifier.
*
* The reset core calls this function as the first step in implementing
* a client's reset_get_by_*() call.
*
* If this function pointer is set to NULL, the reset core will use a
* default implementation, which assumes #reset-cells = <1>, and that
* the DT cell contains a simple integer reset signal ID.
*
* At present, the reset API solely supports device-tree. If this
* changes, other xxx_xlate() functions may be added to support those
* other mechanisms.
*
* @reset_ctl: The reset control struct to hold the translation result.
* @args: The reset specifier values from device tree.
* @return 0 if OK, or a negative error code.
*/
int (*of_xlate)(struct reset_ctl *reset_ctl,
struct fdtdec_phandle_args *args);
/**
* request - Request a translated reset control.
*
* The reset core calls this function as the second step in
* implementing a client's reset_get_by_*() call, following a
* successful xxx_xlate() call.
*
* @reset_ctl: The reset control struct to request; this has been
* filled in by a previoux xxx_xlate() function call.
* @return 0 if OK, or a negative error code.
*/
int (*request)(struct reset_ctl *reset_ctl);
/**
* free - Free a previously requested reset control.
*
* This is the implementation of the client reset_free() API.
*
* @reset_ctl: The reset control to free.
* @return 0 if OK, or a negative error code.
*/
int (*free)(struct reset_ctl *reset_ctl);
/**
* rst_assert - Assert a reset signal.
*
* Note: This function is named rst_assert not assert to avoid
* conflicting with global macro assert().
*
* @reset_ctl: The reset signal to assert.
* @return 0 if OK, or a negative error code.
*/
int (*rst_assert)(struct reset_ctl *reset_ctl);
/**
* rst_deassert - Deassert a reset signal.
*
* @reset_ctl: The reset signal to deassert.
* @return 0 if OK, or a negative error code.
*/
int (*rst_deassert)(struct reset_ctl *reset_ctl);
};
#endif