linux_kernel/include/drm/drm_print.h

/*
 * Copyright (C) 2016 Red Hat
 *
 * Permission is hereby granted, free of charge, to any person obtaining a
 * copy of this software and associated documentation files (the "Software"),
 * to deal in the Software without restriction, including without limitation
 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
 * and/or sell copies of the Software, and to permit persons to whom the
 * Software is furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
 * THE COPYRIGHT HOLDER(S) OR AUTHOR(S) BE LIABLE FOR ANY CLAIM, DAMAGES OR
 * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
 * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
 * OTHER DEALINGS IN THE SOFTWARE.
 *
 * Authors:
 * Rob Clark <robdclark@gmail.com>
 */

#ifndef DRM_PRINT_H_
#define DRM_PRINT_H_

#include <linux/seq_file.h>
#include <linux/device.h>

/**
 * DOC: print
 *
 * A simple wrapper for dev_printk(), seq_printf(), etc.  Allows same
 * debug code to be used for both debugfs and printk logging.
 *
 * For example::
 *
 *     void log_some_info(struct drm_printer *p)
 *     {
 *             drm_printf(p, "foo=%d\n", foo);
 *             drm_printf(p, "bar=%d\n", bar);
 *     }
 *
 *     #ifdef CONFIG_DEBUG_FS
 *     void debugfs_show(struct seq_file *f)
 *     {
 *             struct drm_printer p = drm_seq_file_printer(f);
 *             log_some_info(&p);
 *     }
 *     #endif
 *
 *     void some_other_function(...)
 *     {
 *             struct drm_printer p = drm_info_printer(drm->dev);
 *             log_some_info(&p);
 *     }
 */

/**
 * struct drm_printer - drm output "stream"
 *
 * Do not use struct members directly.  Use drm_printer_seq_file(),
 * drm_printer_info(), etc to initialize.  And drm_printf() for output.
 */
struct drm_printer {
	/* private: */
	void (*printfn)(struct drm_printer *p, struct va_format *vaf);
	void *arg;
	const char *prefix;
};

void __drm_printfn_seq_file(struct drm_printer *p, struct va_format *vaf);
void __drm_printfn_info(struct drm_printer *p, struct va_format *vaf);
void __drm_printfn_debug(struct drm_printer *p, struct va_format *vaf);

void drm_printf(struct drm_printer *p, const char *f, ...);


/**
 * drm_seq_file_printer - construct a &drm_printer that outputs to &seq_file
 * @f:  the &struct seq_file to output to
 *
 * RETURNS:
 * The &drm_printer object
 */
static inline struct drm_printer drm_seq_file_printer(struct seq_file *f)
{
	struct drm_printer p = {
		.printfn = __drm_printfn_seq_file,
		.arg = f,
	};
	return p;
}

/**
 * drm_info_printer - construct a &drm_printer that outputs to dev_printk()
 * @dev: the &struct device pointer
 *
 * RETURNS:
 * The &drm_printer object
 */
static inline struct drm_printer drm_info_printer(struct device *dev)
{
	struct drm_printer p = {
		.printfn = __drm_printfn_info,
		.arg = dev,
	};
	return p;
}

/**
 * drm_debug_printer - construct a &drm_printer that outputs to pr_debug()
 * @prefix: debug output prefix
 *
 * RETURNS:
 * The &drm_printer object
 */
static inline struct drm_printer drm_debug_printer(const char *prefix)
{
	struct drm_printer p = {
		.printfn = __drm_printfn_debug,
		.prefix = prefix
	};
	return p;
}
#endif /* DRM_PRINT_H_ */