drivers/gpu/drm/drm_print.c - linux - Git at Google

 /*
  * 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>
  */

 #include <linux/debugfs.h>
 #include <linux/dynamic_debug.h>
 #include <linux/io.h>
 #include <linux/moduleparam.h>
 #include <linux/seq_file.h>
 #include <linux/slab.h>
 #include <linux/stdarg.h>

 #include <drm/drm.h>
 #include <drm/drm_drv.h>
 #include <drm/drm_print.h>

 /*
  * __drm_debug: Enable debug output.
  * Bitmask of DRM_UT_x. See include/drm/drm_print.h for details.
  */
 unsigned long __drm_debug;
 EXPORT_SYMBOL(__drm_debug);

 MODULE_PARM_DESC(debug, "Enable debug output, where each bit enables a debug category.\n"
 "\t\tBit 0 (0x01)  will enable CORE messages (drm core code)\n"
 "\t\tBit 1 (0x02)  will enable DRIVER messages (drm controller code)\n"
 "\t\tBit 2 (0x04)  will enable KMS messages (modesetting code)\n"
 "\t\tBit 3 (0x08)  will enable PRIME messages (prime code)\n"
 "\t\tBit 4 (0x10)  will enable ATOMIC messages (atomic code)\n"
 "\t\tBit 5 (0x20)  will enable VBL messages (vblank code)\n"
 "\t\tBit 7 (0x80)  will enable LEASE messages (leasing code)\n"
 "\t\tBit 8 (0x100) will enable DP messages (displayport code)");

 #if !defined(CONFIG_DRM_USE_DYNAMIC_DEBUG)
 module_param_named(debug, __drm_debug, ulong, 0600);
 #else
 /* classnames must match vals of enum drm_debug_category */
 DECLARE_DYNDBG_CLASSMAP(drm_debug_classes, DD_CLASS_TYPE_DISJOINT_BITS, 0,
 			"DRM_UT_CORE",
 			"DRM_UT_DRIVER",
 			"DRM_UT_KMS",
 			"DRM_UT_PRIME",
 			"DRM_UT_ATOMIC",
 			"DRM_UT_VBL",
 			"DRM_UT_STATE",
 			"DRM_UT_LEASE",
 			"DRM_UT_DP",
 			"DRM_UT_DRMRES");

 static struct ddebug_class_param drm_debug_bitmap = {
 	.bits = &__drm_debug,
 	.flags = "p",
 	.map = &drm_debug_classes,
 };
 module_param_cb(debug, &param_ops_dyndbg_classes, &drm_debug_bitmap, 0600);
 #endif

 void __drm_puts_coredump(struct drm_printer *p, const char *str)
 {
 	struct drm_print_iterator *iterator = p->arg;
 	ssize_t len;

 	if (!iterator->remain)
 		return;

 	if (iterator->offset < iterator->start) {
 		ssize_t copy;

 		len = strlen(str);

 		if (iterator->offset + len <= iterator->start) {
 			iterator->offset += len;
 			return;
 		}

 		copy = len - (iterator->start - iterator->offset);

 		if (copy > iterator->remain)
 			copy = iterator->remain;

 		/* Copy out the bit of the string that we need */
 		memcpy(iterator->data,
 			str + (iterator->start - iterator->offset), copy);

 		iterator->offset = iterator->start + copy;
 		iterator->remain -= copy;
 	} else {
 		ssize_t pos = iterator->offset - iterator->start;

 		len = min_t(ssize_t, strlen(str), iterator->remain);

 		memcpy(iterator->data + pos, str, len);

 		iterator->offset += len;
 		iterator->remain -= len;
 	}
 }
 EXPORT_SYMBOL(__drm_puts_coredump);

 void __drm_printfn_coredump(struct drm_printer *p, struct va_format *vaf)
 {
 	struct drm_print_iterator *iterator = p->arg;
 	size_t len;
 	char *buf;

 	if (!iterator->remain)
 		return;

 	/* Figure out how big the string will be */
 	len = snprintf(NULL, 0, "%pV", vaf);

 	/* This is the easiest path, we've already advanced beyond the offset */
 	if (iterator->offset + len <= iterator->start) {
 		iterator->offset += len;
 		return;
 	}

 	/* Then check if we can directly copy into the target buffer */
 	if ((iterator->offset >= iterator->start) && (len < iterator->remain)) {
 		ssize_t pos = iterator->offset - iterator->start;

 		snprintf(((char *) iterator->data) + pos,
 			iterator->remain, "%pV", vaf);

 		iterator->offset += len;
 		iterator->remain -= len;

 		return;
 	}

 	/*
 	 * Finally, hit the slow path and make a temporary string to copy over
 	 * using _drm_puts_coredump
 	 */
 	buf = kmalloc(len + 1, GFP_KERNEL | __GFP_NOWARN | __GFP_NORETRY);
 	if (!buf)
 		return;

 	snprintf(buf, len + 1, "%pV", vaf);
 	__drm_puts_coredump(p, (const char *) buf);

 	kfree(buf);
 }
 EXPORT_SYMBOL(__drm_printfn_coredump);

 void __drm_puts_seq_file(struct drm_printer *p, const char *str)
 {
 	seq_puts(p->arg, str);
 }
 EXPORT_SYMBOL(__drm_puts_seq_file);

 void __drm_printfn_seq_file(struct drm_printer *p, struct va_format *vaf)
 {
 	seq_printf(p->arg, "%pV", vaf);
 }
 EXPORT_SYMBOL(__drm_printfn_seq_file);

 void __drm_printfn_info(struct drm_printer *p, struct va_format *vaf)
 {
 	dev_info(p->arg, "[" DRM_NAME "] %pV", vaf);
 }
 EXPORT_SYMBOL(__drm_printfn_info);

 void __drm_printfn_dbg(struct drm_printer *p, struct va_format *vaf)
 {
 	const struct drm_device *drm = p->arg;
 	const struct device *dev = drm ? drm->dev : NULL;
 	enum drm_debug_category category = p->category;
 	const char *prefix = p->prefix ?: "";
 	const char *prefix_pad = p->prefix ? " " : "";

 	if (!__drm_debug_enabled(category))
 		return;

 	/* Note: __builtin_return_address(0) is useless here. */
 	if (dev)
 		dev_printk(KERN_DEBUG, dev, "[" DRM_NAME "]%s%s %pV",
 			   prefix_pad, prefix, vaf);
 	else
 		printk(KERN_DEBUG "[" DRM_NAME "]%s%s %pV",
 		       prefix_pad, prefix, vaf);
 }
 EXPORT_SYMBOL(__drm_printfn_dbg);

 void __drm_printfn_err(struct drm_printer *p, struct va_format *vaf)
 {
 	struct drm_device *drm = p->arg;

 	if (p->prefix)
 		drm_err(drm, "%s %pV", p->prefix, vaf);
 	else
 		drm_err(drm, "%pV", vaf);
 }
 EXPORT_SYMBOL(__drm_printfn_err);

 /**
  * drm_puts - print a const string to a &drm_printer stream
  * @p: the &drm printer
  * @str: const string
  *
  * Allow &drm_printer types that have a constant string
  * option to use it.
  */
 void drm_puts(struct drm_printer *p, const char *str)
 {
 	if (p->puts)
 		p->puts(p, str);
 	else
 		drm_printf(p, "%s", str);
 }
 EXPORT_SYMBOL(drm_puts);

 /**
  * drm_printf - print to a &drm_printer stream
  * @p: the &drm_printer
  * @f: format string
  */
 void drm_printf(struct drm_printer *p, const char *f, ...)
 {
 	va_list args;

 	va_start(args, f);
 	drm_vprintf(p, f, &args);
 	va_end(args);
 }
 EXPORT_SYMBOL(drm_printf);

 /**
  * drm_print_bits - print bits to a &drm_printer stream
  *
  * Print bits (in flag fields for example) in human readable form.
  *
  * @p: the &drm_printer
  * @value: field value.
  * @bits: Array with bit names.
  * @nbits: Size of bit names array.
  */
 void drm_print_bits(struct drm_printer *p, unsigned long value,
 		    const char * const bits[], unsigned int nbits)
 {
 	bool first = true;
 	unsigned int i;

 	if (WARN_ON_ONCE(nbits > BITS_PER_TYPE(value)))
 		nbits = BITS_PER_TYPE(value);

 	for_each_set_bit(i, &value, nbits) {
 		if (WARN_ON_ONCE(!bits[i]))
 			continue;
 		drm_printf(p, "%s%s", first ? "" : ",",
 			   bits[i]);
 		first = false;
 	}
 	if (first)
 		drm_printf(p, "(none)");
 }
 EXPORT_SYMBOL(drm_print_bits);

 void drm_dev_printk(const struct device *dev, const char *level,
 		    const char *format, ...)
 {
 	struct va_format vaf;
 	va_list args;

 	va_start(args, format);
 	vaf.fmt = format;
 	vaf.va = &args;

 	if (dev)
 		dev_printk(level, dev, "[" DRM_NAME ":%ps] %pV",
 			   __builtin_return_address(0), &vaf);
 	else
 		printk("%s" "[" DRM_NAME ":%ps] %pV",
 		       level, __builtin_return_address(0), &vaf);

 	va_end(args);
 }
 EXPORT_SYMBOL(drm_dev_printk);

 void __drm_dev_dbg(struct _ddebug *desc, const struct device *dev,
 		   enum drm_debug_category category, const char *format, ...)
 {
 	struct va_format vaf;
 	va_list args;

 	if (!__drm_debug_enabled(category))
 		return;

 	/* we know we are printing for either syslog, tracefs, or both */
 	va_start(args, format);
 	vaf.fmt = format;
 	vaf.va = &args;

 	if (dev)
 		dev_printk(KERN_DEBUG, dev, "[" DRM_NAME ":%ps] %pV",
 			   __builtin_return_address(0), &vaf);
 	else
 		printk(KERN_DEBUG "[" DRM_NAME ":%ps] %pV",
 		       __builtin_return_address(0), &vaf);

 	va_end(args);
 }
 EXPORT_SYMBOL(__drm_dev_dbg);

 void ___drm_dbg(struct _ddebug *desc, enum drm_debug_category category, const char *format, ...)
 {
 	struct va_format vaf;
 	va_list args;

 	if (!__drm_debug_enabled(category))
 		return;

 	va_start(args, format);
 	vaf.fmt = format;
 	vaf.va = &args;

 	printk(KERN_DEBUG "[" DRM_NAME ":%ps] %pV",
 	       __builtin_return_address(0), &vaf);

 	va_end(args);
 }
 EXPORT_SYMBOL(___drm_dbg);

 void __drm_err(const char *format, ...)
 {
 	struct va_format vaf;
 	va_list args;

 	va_start(args, format);
 	vaf.fmt = format;
 	vaf.va = &args;

 	printk(KERN_ERR "[" DRM_NAME ":%ps] *ERROR* %pV",
 	       __builtin_return_address(0), &vaf);

 	va_end(args);
 }
 EXPORT_SYMBOL(__drm_err);

 /**
  * drm_print_regset32 - print the contents of registers to a
  * &drm_printer stream.
  *
  * @p: the &drm printer
  * @regset: the list of registers to print.
  *
  * Often in driver debug, it's useful to be able to either capture the
  * contents of registers in the steady state using debugfs or at
  * specific points during operation.  This lets the driver have a
  * single list of registers for both.
  */
 void drm_print_regset32(struct drm_printer *p, struct debugfs_regset32 *regset)
 {
 	int namelen = 0;
 	int i;

 	for (i = 0; i < regset->nregs; i++)
 		namelen = max(namelen, (int)strlen(regset->regs[i].name));

 	for (i = 0; i < regset->nregs; i++) {
 		drm_printf(p, "%*s = 0x%08x\n",
 			   namelen, regset->regs[i].name,
 			   readl(regset->base + regset->regs[i].offset));
 	}
 }
 EXPORT_SYMBOL(drm_print_regset32);
	/*
	* 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>
	*/

	#include <linux/debugfs.h>
	#include <linux/dynamic_debug.h>
	#include <linux/io.h>
	#include <linux/moduleparam.h>
	#include <linux/seq_file.h>
	#include <linux/slab.h>
	#include <linux/stdarg.h>

	#include <drm/drm.h>
	#include <drm/drm_drv.h>
	#include <drm/drm_print.h>

	/*
	* __drm_debug: Enable debug output.
	* Bitmask of DRM_UT_x. See include/drm/drm_print.h for details.
	*/
	unsigned long __drm_debug;
	EXPORT_SYMBOL(__drm_debug);

	MODULE_PARM_DESC(debug, "Enable debug output, where each bit enables a debug category.\n"
	"\t\tBit 0 (0x01) will enable CORE messages (drm core code)\n"
	"\t\tBit 1 (0x02) will enable DRIVER messages (drm controller code)\n"
	"\t\tBit 2 (0x04) will enable KMS messages (modesetting code)\n"
	"\t\tBit 3 (0x08) will enable PRIME messages (prime code)\n"
	"\t\tBit 4 (0x10) will enable ATOMIC messages (atomic code)\n"
	"\t\tBit 5 (0x20) will enable VBL messages (vblank code)\n"
	"\t\tBit 7 (0x80) will enable LEASE messages (leasing code)\n"
	"\t\tBit 8 (0x100) will enable DP messages (displayport code)");

	#if !defined(CONFIG_DRM_USE_DYNAMIC_DEBUG)
	module_param_named(debug, __drm_debug, ulong, 0600);
	#else
	/* classnames must match vals of enum drm_debug_category */
	DECLARE_DYNDBG_CLASSMAP(drm_debug_classes, DD_CLASS_TYPE_DISJOINT_BITS, 0,
	"DRM_UT_CORE",
	"DRM_UT_DRIVER",
	"DRM_UT_KMS",
	"DRM_UT_PRIME",
	"DRM_UT_ATOMIC",
	"DRM_UT_VBL",
	"DRM_UT_STATE",
	"DRM_UT_LEASE",
	"DRM_UT_DP",
	"DRM_UT_DRMRES");

	static struct ddebug_class_param drm_debug_bitmap = {
	.bits = &__drm_debug,
	.flags = "p",
	.map = &drm_debug_classes,
	};
	module_param_cb(debug, &param_ops_dyndbg_classes, &drm_debug_bitmap, 0600);
	#endif

	void __drm_puts_coredump(struct drm_printer p, const char str)
	{
	struct drm_print_iterator *iterator = p->arg;
	ssize_t len;

	if (!iterator->remain)
	return;

	if (iterator->offset < iterator->start) {
	ssize_t copy;

	len = strlen(str);

	if (iterator->offset + len <= iterator->start) {
	iterator->offset += len;
	return;
	}

	copy = len - (iterator->start - iterator->offset);

	if (copy > iterator->remain)
	copy = iterator->remain;

	/* Copy out the bit of the string that we need */
	memcpy(iterator->data,
	str + (iterator->start - iterator->offset), copy);

	iterator->offset = iterator->start + copy;
	iterator->remain -= copy;
	} else {
	ssize_t pos = iterator->offset - iterator->start;

	len = min_t(ssize_t, strlen(str), iterator->remain);

	memcpy(iterator->data + pos, str, len);

	iterator->offset += len;
	iterator->remain -= len;
	}
	}
	EXPORT_SYMBOL(__drm_puts_coredump);

	void __drm_printfn_coredump(struct drm_printer p, struct va_format vaf)
	{
	struct drm_print_iterator *iterator = p->arg;
	size_t len;
	char *buf;

	if (!iterator->remain)
	return;

	/* Figure out how big the string will be */
	len = snprintf(NULL, 0, "%pV", vaf);

	/* This is the easiest path, we've already advanced beyond the offset */
	if (iterator->offset + len <= iterator->start) {
	iterator->offset += len;
	return;
	}

	/* Then check if we can directly copy into the target buffer */
	if ((iterator->offset >= iterator->start) && (len < iterator->remain)) {
	ssize_t pos = iterator->offset - iterator->start;

	snprintf(((char *) iterator->data) + pos,
	iterator->remain, "%pV", vaf);

	iterator->offset += len;
	iterator->remain -= len;

	return;
	}

	/*
	* Finally, hit the slow path and make a temporary string to copy over
	* using _drm_puts_coredump
	*/
	buf = kmalloc(len + 1, GFP_KERNEL \| __GFP_NOWARN \| __GFP_NORETRY);
	if (!buf)
	return;

	snprintf(buf, len + 1, "%pV", vaf);
	__drm_puts_coredump(p, (const char *) buf);

	kfree(buf);
	}
	EXPORT_SYMBOL(__drm_printfn_coredump);

	void __drm_puts_seq_file(struct drm_printer p, const char str)
	{
	seq_puts(p->arg, str);
	}
	EXPORT_SYMBOL(__drm_puts_seq_file);

	void __drm_printfn_seq_file(struct drm_printer p, struct va_format vaf)
	{
	seq_printf(p->arg, "%pV", vaf);
	}
	EXPORT_SYMBOL(__drm_printfn_seq_file);

	void __drm_printfn_info(struct drm_printer p, struct va_format vaf)
	{
	dev_info(p->arg, "[" DRM_NAME "] %pV", vaf);
	}
	EXPORT_SYMBOL(__drm_printfn_info);

	void __drm_printfn_dbg(struct drm_printer p, struct va_format vaf)
	{
	const struct drm_device *drm = p->arg;
	const struct device *dev = drm ? drm->dev : NULL;
	enum drm_debug_category category = p->category;
	const char *prefix = p->prefix ?: "";
	const char *prefix_pad = p->prefix ? " " : "";

	if (!__drm_debug_enabled(category))
	return;

	/* Note: __builtin_return_address(0) is useless here. */
	if (dev)
	dev_printk(KERN_DEBUG, dev, "[" DRM_NAME "]%s%s %pV",
	prefix_pad, prefix, vaf);
	else
	printk(KERN_DEBUG "[" DRM_NAME "]%s%s %pV",
	prefix_pad, prefix, vaf);
	}
	EXPORT_SYMBOL(__drm_printfn_dbg);

	void __drm_printfn_err(struct drm_printer p, struct va_format vaf)
	{
	struct drm_device *drm = p->arg;

	if (p->prefix)
	drm_err(drm, "%s %pV", p->prefix, vaf);
	else
	drm_err(drm, "%pV", vaf);
	}
	EXPORT_SYMBOL(__drm_printfn_err);

	/**
	* drm_puts - print a const string to a &drm_printer stream
	* @p: the &drm printer
	* @str: const string
	*
	* Allow &drm_printer types that have a constant string
	* option to use it.
	*/
	void drm_puts(struct drm_printer p, const char str)
	{
	if (p->puts)
	p->puts(p, str);
	else
	drm_printf(p, "%s", str);
	}
	EXPORT_SYMBOL(drm_puts);

	/**
	* drm_printf - print to a &drm_printer stream
	* @p: the &drm_printer
	* @f: format string
	*/
	void drm_printf(struct drm_printer p, const char f, ...)
	{
	va_list args;

	va_start(args, f);
	drm_vprintf(p, f, &args);
	va_end(args);
	}
	EXPORT_SYMBOL(drm_printf);

	/**
	* drm_print_bits - print bits to a &drm_printer stream
	*
	* Print bits (in flag fields for example) in human readable form.
	*
	* @p: the &drm_printer
	* @value: field value.
	* @bits: Array with bit names.
	* @nbits: Size of bit names array.
	*/
	void drm_print_bits(struct drm_printer *p, unsigned long value,
	const char * const bits[], unsigned int nbits)
	{
	bool first = true;
	unsigned int i;

	if (WARN_ON_ONCE(nbits > BITS_PER_TYPE(value)))
	nbits = BITS_PER_TYPE(value);

	for_each_set_bit(i, &value, nbits) {
	if (WARN_ON_ONCE(!bits[i]))
	continue;
	drm_printf(p, "%s%s", first ? "" : ",",
	bits[i]);
	first = false;
	}
	if (first)
	drm_printf(p, "(none)");
	}
	EXPORT_SYMBOL(drm_print_bits);

	void drm_dev_printk(const struct device dev, const char level,
	const char *format, ...)
	{
	struct va_format vaf;
	va_list args;

	va_start(args, format);
	vaf.fmt = format;
	vaf.va = &args;

	if (dev)
	dev_printk(level, dev, "[" DRM_NAME ":%ps] %pV",
	__builtin_return_address(0), &vaf);
	else
	printk("%s" "[" DRM_NAME ":%ps] %pV",
	level, __builtin_return_address(0), &vaf);

	va_end(args);
	}
	EXPORT_SYMBOL(drm_dev_printk);

	void __drm_dev_dbg(struct _ddebug desc, const struct device dev,
	enum drm_debug_category category, const char *format, ...)
	{
	struct va_format vaf;
	va_list args;

	if (!__drm_debug_enabled(category))
	return;

	/* we know we are printing for either syslog, tracefs, or both */
	va_start(args, format);
	vaf.fmt = format;
	vaf.va = &args;

	if (dev)
	dev_printk(KERN_DEBUG, dev, "[" DRM_NAME ":%ps] %pV",
	__builtin_return_address(0), &vaf);
	else
	printk(KERN_DEBUG "[" DRM_NAME ":%ps] %pV",
	__builtin_return_address(0), &vaf);

	va_end(args);
	}
	EXPORT_SYMBOL(__drm_dev_dbg);

	void ___drm_dbg(struct _ddebug desc, enum drm_debug_category category, const char format, ...)
	{
	struct va_format vaf;
	va_list args;

	if (!__drm_debug_enabled(category))
	return;

	va_start(args, format);
	vaf.fmt = format;
	vaf.va = &args;

	printk(KERN_DEBUG "[" DRM_NAME ":%ps] %pV",
	__builtin_return_address(0), &vaf);

	va_end(args);
	}
	EXPORT_SYMBOL(___drm_dbg);

	void __drm_err(const char *format, ...)
	{
	struct va_format vaf;
	va_list args;

	va_start(args, format);
	vaf.fmt = format;
	vaf.va = &args;

	printk(KERN_ERR "[" DRM_NAME ":%ps] ERROR %pV",
	__builtin_return_address(0), &vaf);

	va_end(args);
	}
	EXPORT_SYMBOL(__drm_err);

	/**
	* drm_print_regset32 - print the contents of registers to a
	* &drm_printer stream.
	*
	* @p: the &drm printer
	* @regset: the list of registers to print.
	*
	* Often in driver debug, it's useful to be able to either capture the
	* contents of registers in the steady state using debugfs or at
	* specific points during operation. This lets the driver have a
	* single list of registers for both.
	*/
	void drm_print_regset32(struct drm_printer p, struct debugfs_regset32 regset)
	{
	int namelen = 0;
	int i;

	for (i = 0; i < regset->nregs; i++)
	namelen = max(namelen, (int)strlen(regset->regs[i].name));

	for (i = 0; i < regset->nregs; i++) {
	drm_printf(p, "%*s = 0x%08x\n",
	namelen, regset->regs[i].name,
	readl(regset->base + regset->regs[i].offset));
	}
	}
	EXPORT_SYMBOL(drm_print_regset32);