1/*
2 * Linux WiMAX
3 * Collection of tools to manage debug operations.
4 *
5 *
6 * Copyright (C) 2005-2007 Intel Corporation
7 * Inaky Perez-Gonzalez <inaky.perez-gonzalez@intel.com>
8 *
9 * This program is free software; you can redistribute it and/or
10 * modify it under the terms of the GNU General Public License version
11 * 2 as published by the Free Software Foundation.
12 *
13 * This program is distributed in the hope that it will be useful,
14 * but WITHOUT ANY WARRANTY; without even the implied warranty of
15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
16 * GNU General Public License for more details.
17 *
18 * You should have received a copy of the GNU General Public License
19 * along with this program; if not, write to the Free Software
20 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
21 * 02110-1301, USA.
22 *
23 *
24 * Don't #include this file directly, read on!
25 *
26 *
27 * EXECUTING DEBUGGING ACTIONS OR NOT
28 *
29 * The main thing this framework provides is decission power to take a
30 * debug action (like printing a message) if the current debug level
31 * allows it.
32 *
33 * The decission power is at two levels: at compile-time (what does
34 * not make it is compiled out) and at run-time. The run-time
35 * selection is done per-submodule (as they are declared by the user
36 * of the framework).
37 *
38 * A call to d_test(L) (L being the target debug level) returns true
39 * if the action should be taken because the current debug levels
40 * allow it (both compile and run time).
41 *
42 * It follows that a call to d_test() that can be determined to be
43 * always false at compile time will get the code depending on it
44 * compiled out by optimization.
45 *
46 *
47 * DEBUG LEVELS
48 *
49 * It is up to the caller to define how much a debugging level is.
50 *
51 * Convention sets 0 as "no debug" (so an action marked as debug level 0
52 * will always be taken). The increasing debug levels are used for
53 * increased verbosity.
54 *
55 *
56 * USAGE
57 *
58 * Group the code in modules and submodules inside each module [which
59 * in most cases maps to Linux modules and .c files that compose
60 * those].
61 *
62 *
63 * For each module, there is:
64 *
65 *  - a MODULENAME (single word, legal C identifier)
66 *
67 *  - a debug-levels.h header file that declares the list of
68 *    submodules and that is included by all .c files that use
69 *    the debugging tools. The file name can be anything.
70 *
71 *  - some (optional) .c code to manipulate the runtime debug levels
72 *    through debugfs.
73 *
74 * The debug-levels.h file would look like:
75 *
76 *     #ifndef __debug_levels__h__
77 *     #define __debug_levels__h__
78 *
79 *     #define D_MODULENAME modulename
80 *     #define D_MASTER 10
81 *
82 *     #include <linux/wimax/debug.h>
83 *
84 *     enum d_module {
85 *             D_SUBMODULE_DECLARE(submodule_1),
86 *             D_SUBMODULE_DECLARE(submodule_2),
87 *             ...
88 *             D_SUBMODULE_DECLARE(submodule_N)
89 *     };
90 *
91 *     #endif
92 *
93 * D_MASTER is the maximum compile-time debug level; any debug actions
94 * above this will be out. D_MODULENAME is the module name (legal C
95 * identifier), which has to be unique for each module (to avoid
96 * namespace collisions during linkage). Note those #defines need to
97 * be done before #including debug.h
98 *
99 * We declare N different submodules whose debug level can be
100 * independently controlled during runtime.
101 *
102 * In a .c file of the module (and only in one of them), define the
103 * following code:
104 *
105 *     struct d_level D_LEVEL[] = {
106 *             D_SUBMODULE_DEFINE(submodule_1),
107 *             D_SUBMODULE_DEFINE(submodule_2),
108 *             ...
109 *             D_SUBMODULE_DEFINE(submodule_N),
110 *     };
111 *     size_t D_LEVEL_SIZE = ARRAY_SIZE(D_LEVEL);
112 *
113 * Externs for d_level_MODULENAME and d_level_size_MODULENAME are used
114 * and declared in this file using the D_LEVEL and D_LEVEL_SIZE macros
115 * #defined also in this file.
116 *
117 * To manipulate from user space the levels, create a debugfs dentry
118 * and then register each submodule with:
119 *
120 *     result = d_level_register_debugfs("PREFIX_", submodule_X, parent);
121 *     if (result < 0)
122 *            goto error;
123 *
124 * Where PREFIX_ is a name of your chosing. This will create debugfs
125 * file with a single numeric value that can be use to tweak it. To
126 * remove the entires, just use debugfs_remove_recursive() on 'parent'.
127 *
128 * NOTE: remember that even if this will show attached to some
129 *     particular instance of a device, the settings are *global*.
130 *
131 *
132 * On each submodule (for example, .c files), the debug infrastructure
133 * should be included like this:
134 *
135 *     #define D_SUBMODULE submodule_x     // matches one in debug-levels.h
136 *     #include "debug-levels.h"
137 *
138 * after #including all your include files.
139 *
140 *
141 * Now you can use the d_*() macros below [d_test(), d_fnstart(),
142 * d_fnend(), d_printf(), d_dump()].
143 *
144 * If their debug level is greater than D_MASTER, they will be
145 * compiled out.
146 *
147 * If their debug level is lower or equal than D_MASTER but greater
148 * than the current debug level of their submodule, they'll be
149 * ignored.
150 *
151 * Otherwise, the action will be performed.
152 */
153#ifndef __debug__h__
154#define __debug__h__
155
156#include <linux/types.h>
157#include <linux/slab.h>
158
159struct device;
160
161/* Backend stuff */
162
163/*
164 * Debug backend: generate a message header from a 'struct device'
165 *
166 * @head: buffer where to place the header
167 * @head_size: length of @head
168 * @dev: pointer to device used to generate a header from. If NULL,
169 *     an empty ("") header is generated.
170 */
171static inline
172void __d_head(char *head, size_t head_size,
173	      struct device *dev)
174{
175	if (dev == NULL)
176		head[0] = 0;
177	else if ((unsigned long)dev < 4096) {
178		printk(KERN_ERR "E: Corrupt dev %p\n", dev);
179		WARN_ON(1);
180	} else
181		snprintf(head, head_size, "%s %s: ",
182			 dev_driver_string(dev), dev_name(dev));
183}
184
185
186/*
187 * Debug backend: log some message if debugging is enabled
188 *
189 * @l: intended debug level
190 * @tag: tag to prefix the message with
191 * @dev: 'struct device' associated to this message
192 * @f: printf-like format and arguments
193 *
194 * Note this is optimized out if it doesn't pass the compile-time
195 * check; however, it is *always* compiled. This is useful to make
196 * sure the printf-like formats and variables are always checked and
197 * they don't get bit rot if you have all the debugging disabled.
198 */
199#define _d_printf(l, tag, dev, f, a...)					\
200do {									\
201	char head[64];							\
202	if (!d_test(l))							\
203		break;							\
204	__d_head(head, sizeof(head), dev);				\
205	printk(KERN_ERR "%s%s%s: " f, head, __func__, tag, ##a);	\
206} while (0)
207
208
209/*
210 * CPP sintatic sugar to generate A_B like symbol names when one of
211 * the arguments is a a preprocessor #define.
212 */
213#define __D_PASTE__(varname, modulename) varname##_##modulename
214#define __D_PASTE(varname, modulename) (__D_PASTE__(varname, modulename))
215#define _D_SUBMODULE_INDEX(_name) (D_SUBMODULE_DECLARE(_name))
216
217
218/*
219 * Store a submodule's runtime debug level and name
220 */
221struct d_level {
222	u8 level;
223	const char *name;
224};
225
226
227/*
228 * List of available submodules and their debug levels
229 *
230 * We call them d_level_MODULENAME and d_level_size_MODULENAME; the
231 * macros D_LEVEL and D_LEVEL_SIZE contain the name already for
232 * convenience.
233 *
234 * This array and the size are defined on some .c file that is part of
235 * the current module.
236 */
237#define D_LEVEL __D_PASTE(d_level, D_MODULENAME)
238#define D_LEVEL_SIZE __D_PASTE(d_level_size, D_MODULENAME)
239
240extern struct d_level D_LEVEL[];
241extern size_t D_LEVEL_SIZE;
242
243
244/*
245 * Frontend stuff
246 *
247 *
248 * Stuff you need to declare prior to using the actual "debug" actions
249 * (defined below).
250 */
251
252#ifndef D_MODULENAME
253#error D_MODULENAME is not defined in your debug-levels.h file
254/**
255 * D_MODULE - Name of the current module
256 *
257 * #define in your module's debug-levels.h, making sure it is
258 * unique. This has to be a legal C identifier.
259 */
260#define D_MODULENAME undefined_modulename
261#endif
262
263
264#ifndef D_MASTER
265#warning D_MASTER not defined, but debug.h included! [see docs]
266/**
267 * D_MASTER - Compile time maximum debug level
268 *
269 * #define in your debug-levels.h file to the maximum debug level the
270 * runtime code will be allowed to have. This allows you to provide a
271 * main knob.
272 *
273 * Anything above that level will be optimized out of the compile.
274 *
275 * Defaults to zero (no debug code compiled in).
276 *
277 * Maximum one definition per module (at the debug-levels.h file).
278 */
279#define D_MASTER 0
280#endif
281
282#ifndef D_SUBMODULE
283#error D_SUBMODULE not defined, but debug.h included! [see docs]
284/**
285 * D_SUBMODULE - Name of the current submodule
286 *
287 * #define in your submodule .c file before #including debug-levels.h
288 * to the name of the current submodule as previously declared and
289 * defined with D_SUBMODULE_DECLARE() (in your module's
290 * debug-levels.h) and D_SUBMODULE_DEFINE().
291 *
292 * This is used to provide runtime-control over the debug levels.
293 *
294 * Maximum one per .c file! Can be shared among different .c files
295 * (meaning they belong to the same submodule categorization).
296 */
297#define D_SUBMODULE undefined_module
298#endif
299
300
301/**
302 * D_SUBMODULE_DECLARE - Declare a submodule for runtime debug level control
303 *
304 * @_name: name of the submodule, restricted to the chars that make up a
305 *     valid C identifier ([a-zA-Z0-9_]).
306 *
307 * Declare in the module's debug-levels.h header file as:
308 *
309 * enum d_module {
310 *         D_SUBMODULE_DECLARE(submodule_1),
311 *         D_SUBMODULE_DECLARE(submodule_2),
312 *         D_SUBMODULE_DECLARE(submodule_3),
313 * };
314 *
315 * Some corresponding .c file needs to have a matching
316 * D_SUBMODULE_DEFINE().
317 */
318#define D_SUBMODULE_DECLARE(_name) __D_SUBMODULE_##_name
319
320
321/**
322 * D_SUBMODULE_DEFINE - Define a submodule for runtime debug level control
323 *
324 * @_name: name of the submodule, restricted to the chars that make up a
325 *     valid C identifier ([a-zA-Z0-9_]).
326 *
327 * Use once per module (in some .c file) as:
328 *
329 * static
330 * struct d_level d_level_SUBMODULENAME[] = {
331 *         D_SUBMODULE_DEFINE(submodule_1),
332 *         D_SUBMODULE_DEFINE(submodule_2),
333 *         D_SUBMODULE_DEFINE(submodule_3),
334 * };
335 * size_t d_level_size_SUBDMODULENAME = ARRAY_SIZE(d_level_SUBDMODULENAME);
336 *
337 * Matching D_SUBMODULE_DECLARE()s have to be present in a
338 * debug-levels.h header file.
339 */
340#define D_SUBMODULE_DEFINE(_name)		\
341[__D_SUBMODULE_##_name] = {			\
342	.level = 0,				\
343	.name = #_name				\
344}
345
346
347
348/* The actual "debug" operations */
349
350
351/**
352 * d_test - Returns true if debugging should be enabled
353 *
354 * @l: intended debug level (unsigned)
355 *
356 * If the master debug switch is enabled and the current settings are
357 * higher or equal to the requested level, then debugging
358 * output/actions should be enabled.
359 *
360 * NOTE:
361 *
362 * This needs to be coded so that it can be evaluated in compile
363 * time; this is why the ugly BUG_ON() is placed in there, so the
364 * D_MASTER evaluation compiles all out if it is compile-time false.
365 */
366#define d_test(l)							\
367({									\
368	unsigned __l = l;	/* type enforcer */			\
369	(D_MASTER) >= __l						\
370	&& ({								\
371		BUG_ON(_D_SUBMODULE_INDEX(D_SUBMODULE) >= D_LEVEL_SIZE);\
372		D_LEVEL[_D_SUBMODULE_INDEX(D_SUBMODULE)].level >= __l;	\
373	});								\
374})
375
376
377/**
378 * d_fnstart - log message at function start if debugging enabled
379 *
380 * @l: intended debug level
381 * @_dev: 'struct device' pointer, NULL if none (for context)
382 * @f: printf-like format and arguments
383 */
384#define d_fnstart(l, _dev, f, a...) _d_printf(l, " FNSTART", _dev, f, ## a)
385
386
387/**
388 * d_fnend - log message at function end if debugging enabled
389 *
390 * @l: intended debug level
391 * @_dev: 'struct device' pointer, NULL if none (for context)
392 * @f: printf-like format and arguments
393 */
394#define d_fnend(l, _dev, f, a...) _d_printf(l, " FNEND", _dev, f, ## a)
395
396
397/**
398 * d_printf - log message if debugging enabled
399 *
400 * @l: intended debug level
401 * @_dev: 'struct device' pointer, NULL if none (for context)
402 * @f: printf-like format and arguments
403 */
404#define d_printf(l, _dev, f, a...) _d_printf(l, "", _dev, f, ## a)
405
406
407/**
408 * d_dump - log buffer hex dump if debugging enabled
409 *
410 * @l: intended debug level
411 * @_dev: 'struct device' pointer, NULL if none (for context)
412 * @f: printf-like format and arguments
413 */
414#define d_dump(l, dev, ptr, size)			\
415do {							\
416	char head[64];					\
417	if (!d_test(l))					\
418		break;					\
419	__d_head(head, sizeof(head), dev);		\
420	print_hex_dump(KERN_ERR, head, 0, 16, 1,	\
421		       ((void *) ptr), (size), 0);	\
422} while (0)
423
424
425/**
426 * Export a submodule's debug level over debugfs as PREFIXSUBMODULE
427 *
428 * @prefix: string to prefix the name with
429 * @submodule: name of submodule (not a string, just the name)
430 * @dentry: debugfs parent dentry
431 *
432 * Returns: 0 if ok, < 0 errno on error.
433 *
434 * For removing, just use debugfs_remove_recursive() on the parent.
435 */
436#define d_level_register_debugfs(prefix, name, parent)			\
437({									\
438	int rc;								\
439	struct dentry *fd;						\
440	struct dentry *verify_parent_type = parent;			\
441	fd = debugfs_create_u8(						\
442		prefix #name, 0600, verify_parent_type,			\
443		&(D_LEVEL[__D_SUBMODULE_ ## name].level));		\
444	rc = PTR_ERR(fd);						\
445	if (IS_ERR(fd) && rc != -ENODEV)				\
446		printk(KERN_ERR "%s: Can't create debugfs entry %s: "	\
447		       "%d\n", __func__, prefix #name, rc);		\
448	else								\
449		rc = 0;							\
450	rc;								\
451})
452
453
454static inline
455void d_submodule_set(struct d_level *d_level, size_t d_level_size,
456		     const char *submodule, u8 level, const char *tag)
457{
458	struct d_level *itr, *top;
459	int index = -1;
460
461	for (itr = d_level, top = itr + d_level_size; itr < top; itr++) {
462		index++;
463		if (itr->name == NULL) {
464			printk(KERN_ERR "%s: itr->name NULL?? (%p, #%d)\n",
465			       tag, itr, index);
466			continue;
467		}
468		if (!strcmp(itr->name, submodule)) {
469			itr->level = level;
470			return;
471		}
472	}
473	printk(KERN_ERR "%s: unknown submodule %s\n", tag, submodule);
474}
475
476
477/**
478 * d_parse_params - Parse a string with debug parameters from the
479 * command line
480 *
481 * @d_level: level structure (D_LEVEL)
482 * @d_level_size: number of items in the level structure
483 *     (D_LEVEL_SIZE).
484 * @_params: string with the parameters; this is a space (not tab!)
485 *     separated list of NAME:VALUE, where value is the debug level
486 *     and NAME is the name of the submodule.
487 * @tag: string for error messages (example: MODULE.ARGNAME).
488 */
489static inline
490void d_parse_params(struct d_level *d_level, size_t d_level_size,
491		    const char *_params, const char *tag)
492{
493	char submodule[130], *params, *params_orig, *token, *colon;
494	unsigned level, tokens;
495
496	if (_params == NULL)
497		return;
498	params_orig = kstrdup(_params, GFP_KERNEL);
499	params = params_orig;
500	while (1) {
501		token = strsep(&params, " ");
502		if (token == NULL)
503			break;
504		if (*token == '\0')	/* eat joint spaces */
505			continue;
506		/* kernel's sscanf %s eats until whitespace, so we
507		 * replace : by \n so it doesn't get eaten later by
508		 * strsep */
509		colon = strchr(token, ':');
510		if (colon != NULL)
511			*colon = '\n';
512		tokens = sscanf(token, "%s\n%u", submodule, &level);
513		if (colon != NULL)
514			*colon = ':';	/* set back, for error messages */
515		if (tokens == 2)
516			d_submodule_set(d_level, d_level_size,
517					submodule, level, tag);
518		else
519			printk(KERN_ERR "%s: can't parse '%s' as a "
520			       "SUBMODULE:LEVEL (%d tokens)\n",
521			       tag, token, tokens);
522	}
523	kfree(params_orig);
524}
525
526#endif /* #ifndef __debug__h__ */
527