[PATCH 2/5] introduce-resume-dependency.patch

Tim Niemeyer tim.niemeyer at mastersword.de
Tue Jun 3 12:04:48 CEST 2008


Hallo Andy,

in Documentation/power/devices.txt:
"The ordering of the device tree is defined by the order in which
devices get registered"
So, for what we need this resume dependency framework?

* Andy Green <andy at openmoko.com> [02-06-08 13:27]:
> Defines a way for drivers to defer execution of resume callbacks
> until one or more other driver they are dependent on has itself
> resumed.
> 
> Signed-off-by: Andy Green <andy at openmoko.com>
> ---
> 
>  include/linux/resume-dependency.h |   78 +++++++++++++++++++++++++++++++++++++
>  1 files changed, 78 insertions(+), 0 deletions(-)
>  create mode 100644 include/linux/resume-dependency.h
> 
> diff --git a/include/linux/resume-dependency.h b/include/linux/resume-dependency.h
> new file mode 100644
> index 0000000..b13aa3e
> --- /dev/null
> +++ b/include/linux/resume-dependency.h
> @@ -0,0 +1,78 @@
> +#ifndef __RESUME_DEPENDENCY_H__
> +#define __RESUME_DEPENDENCY_H__
> +
> +/* Resume dependency framework
> + *
> + * (C) 2008 Openmoko, Inc.
> + * Author: Andy Green <andy at openmoko.com>
> + *
> + * This program is free software; you can redistribute it and/or
> + * modify it under the terms of the GNU General Public License as
> + * published by the Free Software Foundation; version 2.1.
> + *
> + * This program is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> + * GNU General Public License for more details.
> + *
> + * You should have received a copy of the GNU General Public License
> + * along with this program; if not, write to the Free Software
> + * Foundation, Inc., 59 Temple Place, Suite 330, Boston,
> + * MA 02111-1307 USA
> + *
> + */
> +
> +#include <linux/list.h>
> +
> +struct resume_dependency {
> +	struct list_head list;
> +
> +	void (*callback)(void *); /* called with context as arg */
> +	void * context;
> +	int called_flag; /* set to 1 after called, use for multi dep */
> +};
> +
> +/* if you are a driver accept to have other drivers as dependencies, you need to
> + * instantiate a struct resume_dependency above, then initialize it by invoking
> + * init_resume_dependency_list() on it
> + */
> +
> +#define init_resume_dependency_list(_head) \
> +	INIT_LIST_HEAD(&_head.list);
> +
> +
> +/* if your resume function depends on something else being resumed first, you
> + * can register the dependency by calling this in your suspend function with
> + * head being the list held by the thing you are dependent on, and dep being
> + * your struct resume_dependency
> + */
> +
> +#define register_resume_dependency(_head, _dep) { \
> +	_dep->called_flag = 0; \
> +	list_add(&_dep->list, &_head->list); \
> +}
> +
> +/* In the resume function that things can be dependent on, at the end you
> + * invoke this macro.  This calls back the dependent resumes now it is safe to
> + * use the resumed thing they were dependent on.
> + */
> +
> +#define callback_all_resume_dependencies(_head) { \
> +	struct list_head *_pos, *_q; \
> +	struct resume_dependency *_dep; \
> +\
> +	list_for_each_safe(pos, _q, &_head.list) { \
> +		_dep = list_entry(_pos, struct resume_dependency, list); \
> +		_dep->called_flag = 1; \
> +		(_dep->callback)(dep->context); \
> +		list_del(_pos); \
> +	} \
> +}
> +
> +/* if your resume action is dependent on multiple drivers being resumed already,
> + * register the same callback with each driver you are dependent on, and check
> + * .called_flag for all of the struct resume_dependency.  When they are all 1
> + * you know it is the last callback and you can resume, otherwise just return
> + */
> +
> +#endif
> 
> 


Tim Niemeyer
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