sound/hda/hdac_sysfs.c - linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0
 /*
  * sysfs support for HD-audio core device
  */

 #include <linux/slab.h>
 #include <linux/sysfs.h>
 #include <linux/device.h>
 #include <sound/core.h>
 #include <sound/hdaudio.h>
 #include "local.h"

 struct hdac_widget_tree {
 	struct kobject *root;
 	struct kobject *afg;
 	struct kobject **nodes;
 };

 #define CODEC_ATTR(type)					\
 static ssize_t type##_show(struct device *dev,			\
 			   struct device_attribute *attr,	\
 			   char *buf)				\
 {								\
 	struct hdac_device *codec = dev_to_hdac_dev(dev);	\
 	return sysfs_emit(buf, "0x%x\n", codec->type);		\
 } \
 static DEVICE_ATTR_RO(type)

 #define CODEC_ATTR_STR(type)					\
 static ssize_t type##_show(struct device *dev,			\
 			     struct device_attribute *attr,	\
 					char *buf)		\
 {								\
 	struct hdac_device *codec = dev_to_hdac_dev(dev);	\
 	return sysfs_emit(buf, "%s\n",				\
 			  codec->type ? codec->type : "");	\
 } \
 static DEVICE_ATTR_RO(type)

 CODEC_ATTR(type);
 CODEC_ATTR(vendor_id);
 CODEC_ATTR(subsystem_id);
 CODEC_ATTR(revision_id);
 CODEC_ATTR(afg);
 CODEC_ATTR(mfg);
 CODEC_ATTR_STR(vendor_name);
 CODEC_ATTR_STR(chip_name);

 static ssize_t modalias_show(struct device *dev, struct device_attribute *attr,
 			     char *buf)
 {
 	return snd_hdac_codec_modalias(dev_to_hdac_dev(dev), buf, 256);
 }
 static DEVICE_ATTR_RO(modalias);

 static struct attribute *hdac_dev_attrs[] = {
 	&dev_attr_type.attr,
 	&dev_attr_vendor_id.attr,
 	&dev_attr_subsystem_id.attr,
 	&dev_attr_revision_id.attr,
 	&dev_attr_afg.attr,
 	&dev_attr_mfg.attr,
 	&dev_attr_vendor_name.attr,
 	&dev_attr_chip_name.attr,
 	&dev_attr_modalias.attr,
 	NULL
 };

 static const struct attribute_group hdac_dev_attr_group = {
 	.attrs	= hdac_dev_attrs,
 };

 const struct attribute_group *hdac_dev_attr_groups[] = {
 	&hdac_dev_attr_group,
 	NULL
 };

 /*
  * Widget tree sysfs
  *
  * This is a tree showing the attributes of each widget.  It appears like
  * /sys/bus/hdaudioC0D0/widgets/04/caps
  */

 struct widget_attribute;

 struct widget_attribute {
 	struct attribute	attr;
 	ssize_t (*show)(struct hdac_device *codec, hda_nid_t nid,
 			struct widget_attribute *attr, char *buf);
 	ssize_t (*store)(struct hdac_device *codec, hda_nid_t nid,
 			 struct widget_attribute *attr,
 			 const char *buf, size_t count);
 };

 static int get_codec_nid(struct kobject *kobj, struct hdac_device **codecp)
 {
 	struct device *dev = kobj_to_dev(kobj->parent->parent);
 	int nid;
 	ssize_t ret;

 	ret = kstrtoint(kobj->name, 16, &nid);
 	if (ret < 0)
 		return ret;
 	*codecp = dev_to_hdac_dev(dev);
 	return nid;
 }

 static ssize_t widget_attr_show(struct kobject *kobj, struct attribute *attr,
 				char *buf)
 {
 	struct widget_attribute *wid_attr =
 		container_of(attr, struct widget_attribute, attr);
 	struct hdac_device *codec;
 	int nid;

 	if (!wid_attr->show)
 		return -EIO;
 	nid = get_codec_nid(kobj, &codec);
 	if (nid < 0)
 		return nid;
 	return wid_attr->show(codec, nid, wid_attr, buf);
 }

 static ssize_t widget_attr_store(struct kobject *kobj, struct attribute *attr,
 				 const char *buf, size_t count)
 {
 	struct widget_attribute *wid_attr =
 		container_of(attr, struct widget_attribute, attr);
 	struct hdac_device *codec;
 	int nid;

 	if (!wid_attr->store)
 		return -EIO;
 	nid = get_codec_nid(kobj, &codec);
 	if (nid < 0)
 		return nid;
 	return wid_attr->store(codec, nid, wid_attr, buf, count);
 }

 static const struct sysfs_ops widget_sysfs_ops = {
 	.show	= widget_attr_show,
 	.store	= widget_attr_store,
 };

 static void widget_release(struct kobject *kobj)
 {
 	kfree(kobj);
 }

 static const struct kobj_type widget_ktype = {
 	.release	= widget_release,
 	.sysfs_ops	= &widget_sysfs_ops,
 };

 #define WIDGET_ATTR_RO(_name) \
 	struct widget_attribute wid_attr_##_name = __ATTR_RO(_name)
 #define WIDGET_ATTR_RW(_name) \
 	struct widget_attribute wid_attr_##_name = __ATTR_RW(_name)

 static ssize_t caps_show(struct hdac_device *codec, hda_nid_t nid,
 			struct widget_attribute *attr, char *buf)
 {
 	return sysfs_emit(buf, "0x%08x\n", get_wcaps(codec, nid));
 }

 static ssize_t pin_caps_show(struct hdac_device *codec, hda_nid_t nid,
 			     struct widget_attribute *attr, char *buf)
 {
 	if (get_wcaps_type(get_wcaps(codec, nid)) != AC_WID_PIN)
 		return 0;
 	return sysfs_emit(buf, "0x%08x\n",
 			  snd_hdac_read_parm(codec, nid, AC_PAR_PIN_CAP));
 }

 static ssize_t pin_cfg_show(struct hdac_device *codec, hda_nid_t nid,
 			    struct widget_attribute *attr, char *buf)
 {
 	unsigned int val;

 	if (get_wcaps_type(get_wcaps(codec, nid)) != AC_WID_PIN)
 		return 0;
 	if (snd_hdac_read(codec, nid, AC_VERB_GET_CONFIG_DEFAULT, 0, &val))
 		return 0;
 	return sysfs_emit(buf, "0x%08x\n", val);
 }

 static bool has_pcm_cap(struct hdac_device *codec, hda_nid_t nid)
 {
 	if (nid == codec->afg || nid == codec->mfg)
 		return true;
 	switch (get_wcaps_type(get_wcaps(codec, nid))) {
 	case AC_WID_AUD_OUT:
 	case AC_WID_AUD_IN:
 		return true;
 	default:
 		return false;
 	}
 }

 static ssize_t pcm_caps_show(struct hdac_device *codec, hda_nid_t nid,
 			     struct widget_attribute *attr, char *buf)
 {
 	if (!has_pcm_cap(codec, nid))
 		return 0;
 	return sysfs_emit(buf, "0x%08x\n",
 			  snd_hdac_read_parm(codec, nid, AC_PAR_PCM));
 }

 static ssize_t pcm_formats_show(struct hdac_device *codec, hda_nid_t nid,
 				struct widget_attribute *attr, char *buf)
 {
 	if (!has_pcm_cap(codec, nid))
 		return 0;
 	return sysfs_emit(buf, "0x%08x\n",
 			  snd_hdac_read_parm(codec, nid, AC_PAR_STREAM));
 }

 static ssize_t amp_in_caps_show(struct hdac_device *codec, hda_nid_t nid,
 				struct widget_attribute *attr, char *buf)
 {
 	if (nid != codec->afg && !(get_wcaps(codec, nid) & AC_WCAP_IN_AMP))
 		return 0;
 	return sysfs_emit(buf, "0x%08x\n",
 			  snd_hdac_read_parm(codec, nid, AC_PAR_AMP_IN_CAP));
 }

 static ssize_t amp_out_caps_show(struct hdac_device *codec, hda_nid_t nid,
 				 struct widget_attribute *attr, char *buf)
 {
 	if (nid != codec->afg && !(get_wcaps(codec, nid) & AC_WCAP_OUT_AMP))
 		return 0;
 	return sysfs_emit(buf, "0x%08x\n",
 			  snd_hdac_read_parm(codec, nid, AC_PAR_AMP_OUT_CAP));
 }

 static ssize_t power_caps_show(struct hdac_device *codec, hda_nid_t nid,
 			       struct widget_attribute *attr, char *buf)
 {
 	if (nid != codec->afg && !(get_wcaps(codec, nid) & AC_WCAP_POWER))
 		return 0;
 	return sysfs_emit(buf, "0x%08x\n",
 			  snd_hdac_read_parm(codec, nid, AC_PAR_POWER_STATE));
 }

 static ssize_t gpio_caps_show(struct hdac_device *codec, hda_nid_t nid,
 			      struct widget_attribute *attr, char *buf)
 {
 	return sysfs_emit(buf, "0x%08x\n",
 			  snd_hdac_read_parm(codec, nid, AC_PAR_GPIO_CAP));
 }

 static ssize_t connections_show(struct hdac_device *codec, hda_nid_t nid,
 				struct widget_attribute *attr, char *buf)
 {
 	hda_nid_t list[32];
 	int i, nconns;
 	ssize_t ret = 0;

 	nconns = snd_hdac_get_connections(codec, nid, list, ARRAY_SIZE(list));
 	if (nconns <= 0)
 		return nconns;
 	for (i = 0; i < nconns; i++)
 		ret += sysfs_emit_at(buf,  ret, "%s0x%02x", i ? " " : "", list[i]);
 	ret += sysfs_emit_at(buf, ret, "\n");
 	return ret;
 }

 static WIDGET_ATTR_RO(caps);
 static WIDGET_ATTR_RO(pin_caps);
 static WIDGET_ATTR_RO(pin_cfg);
 static WIDGET_ATTR_RO(pcm_caps);
 static WIDGET_ATTR_RO(pcm_formats);
 static WIDGET_ATTR_RO(amp_in_caps);
 static WIDGET_ATTR_RO(amp_out_caps);
 static WIDGET_ATTR_RO(power_caps);
 static WIDGET_ATTR_RO(gpio_caps);
 static WIDGET_ATTR_RO(connections);

 static struct attribute *widget_node_attrs[] = {
 	&wid_attr_caps.attr,
 	&wid_attr_pin_caps.attr,
 	&wid_attr_pin_cfg.attr,
 	&wid_attr_pcm_caps.attr,
 	&wid_attr_pcm_formats.attr,
 	&wid_attr_amp_in_caps.attr,
 	&wid_attr_amp_out_caps.attr,
 	&wid_attr_power_caps.attr,
 	&wid_attr_connections.attr,
 	NULL,
 };

 static struct attribute *widget_afg_attrs[] = {
 	&wid_attr_pcm_caps.attr,
 	&wid_attr_pcm_formats.attr,
 	&wid_attr_amp_in_caps.attr,
 	&wid_attr_amp_out_caps.attr,
 	&wid_attr_power_caps.attr,
 	&wid_attr_gpio_caps.attr,
 	NULL,
 };

 static const struct attribute_group widget_node_group = {
 	.attrs = widget_node_attrs,
 };

 static const struct attribute_group widget_afg_group = {
 	.attrs = widget_afg_attrs,
 };

 static void free_widget_node(struct kobject *kobj,
 			     const struct attribute_group *group)
 {
 	if (kobj) {
 		sysfs_remove_group(kobj, group);
 		kobject_put(kobj);
 	}
 }

 static void widget_tree_free(struct hdac_device *codec)
 {
 	struct hdac_widget_tree *tree = codec->widgets;
 	struct kobject **p;

 	if (!tree)
 		return;
 	free_widget_node(tree->afg, &widget_afg_group);
 	if (tree->nodes) {
 		for (p = tree->nodes; *p; p++)
 			free_widget_node(*p, &widget_node_group);
 		kfree(tree->nodes);
 	}
 	kobject_put(tree->root);
 	kfree(tree);
 	codec->widgets = NULL;
 }

 static int add_widget_node(struct kobject *parent, hda_nid_t nid,
 			   const struct attribute_group *group,
 			   struct kobject **res)
 {
 	struct kobject *kobj = kzalloc(sizeof(*kobj), GFP_KERNEL);
 	int err;

 	if (!kobj)
 		return -ENOMEM;
 	kobject_init(kobj, &widget_ktype);
 	err = kobject_add(kobj, parent, "%02x", nid);
 	if (err < 0) {
 		kobject_put(kobj);
 		return err;
 	}
 	err = sysfs_create_group(kobj, group);
 	if (err < 0) {
 		kobject_put(kobj);
 		return err;
 	}

 	*res = kobj;
 	return 0;
 }

 static int widget_tree_create(struct hdac_device *codec)
 {
 	struct hdac_widget_tree *tree;
 	int i, err;
 	hda_nid_t nid;

 	tree = codec->widgets = kzalloc(sizeof(*tree), GFP_KERNEL);
 	if (!tree)
 		return -ENOMEM;

 	tree->root = kobject_create_and_add("widgets", &codec->dev.kobj);
 	if (!tree->root)
 		return -ENOMEM;

 	tree->nodes = kcalloc(codec->num_nodes + 1, sizeof(*tree->nodes),
 			      GFP_KERNEL);
 	if (!tree->nodes)
 		return -ENOMEM;

 	for (i = 0, nid = codec->start_nid; i < codec->num_nodes; i++, nid++) {
 		err = add_widget_node(tree->root, nid, &widget_node_group,
 				      &tree->nodes[i]);
 		if (err < 0)
 			return err;
 	}

 	if (codec->afg) {
 		err = add_widget_node(tree->root, codec->afg,
 				      &widget_afg_group, &tree->afg);
 		if (err < 0)
 			return err;
 	}

 	kobject_uevent(tree->root, KOBJ_CHANGE);
 	return 0;
 }

 /* call with codec->widget_lock held */
 int hda_widget_sysfs_init(struct hdac_device *codec)
 {
 	int err;

 	if (codec->widgets)
 		return 0; /* already created */

 	err = widget_tree_create(codec);
 	if (err < 0) {
 		widget_tree_free(codec);
 		return err;
 	}

 	return 0;
 }

 /* call with codec->widget_lock held */
 void hda_widget_sysfs_exit(struct hdac_device *codec)
 {
 	widget_tree_free(codec);
 }

 /* call with codec->widget_lock held */
 int hda_widget_sysfs_reinit(struct hdac_device *codec,
 			    hda_nid_t start_nid, int num_nodes)
 {
 	struct hdac_widget_tree *tree;
 	hda_nid_t end_nid = start_nid + num_nodes;
 	hda_nid_t nid;
 	int i;

 	if (!codec->widgets)
 		return 0;

 	tree = kmemdup(codec->widgets, sizeof(*tree), GFP_KERNEL);
 	if (!tree)
 		return -ENOMEM;

 	tree->nodes = kcalloc(num_nodes + 1, sizeof(*tree->nodes), GFP_KERNEL);
 	if (!tree->nodes) {
 		kfree(tree);
 		return -ENOMEM;
 	}

 	/* prune non-existing nodes */
 	for (i = 0, nid = codec->start_nid; i < codec->num_nodes; i++, nid++) {
 		if (nid < start_nid || nid >= end_nid)
 			free_widget_node(codec->widgets->nodes[i],
 					 &widget_node_group);
 	}

 	/* add new nodes */
 	for (i = 0, nid = start_nid; i < num_nodes; i++, nid++) {
 		if (nid < codec->start_nid || nid >= codec->end_nid)
 			add_widget_node(tree->root, nid, &widget_node_group,
 					&tree->nodes[i]);
 		else
 			tree->nodes[i] =
 				codec->widgets->nodes[nid - codec->start_nid];
 	}

 	/* replace with the new tree */
 	kfree(codec->widgets->nodes);
 	kfree(codec->widgets);
 	codec->widgets = tree;

 	kobject_uevent(tree->root, KOBJ_CHANGE);
 	return 0;
 }
	// SPDX-License-Identifier: GPL-2.0
	/*
	* sysfs support for HD-audio core device
	*/

	#include <linux/slab.h>
	#include <linux/sysfs.h>
	#include <linux/device.h>
	#include <sound/core.h>
	#include <sound/hdaudio.h>
	#include "local.h"

	struct hdac_widget_tree {
	struct kobject *root;
	struct kobject *afg;
	struct kobject **nodes;
	};

	#define CODEC_ATTR(type) \
	static ssize_t type##_show(struct device *dev, \
	struct device_attribute *attr, \
	char *buf) \
	{ \
	struct hdac_device *codec = dev_to_hdac_dev(dev); \
	return sysfs_emit(buf, "0x%x\n", codec->type); \
	} \
	static DEVICE_ATTR_RO(type)

	#define CODEC_ATTR_STR(type) \
	static ssize_t type##_show(struct device *dev, \
	struct device_attribute *attr, \
	char *buf) \
	{ \
	struct hdac_device *codec = dev_to_hdac_dev(dev); \
	return sysfs_emit(buf, "%s\n", \
	codec->type ? codec->type : ""); \
	} \
	static DEVICE_ATTR_RO(type)

	CODEC_ATTR(type);
	CODEC_ATTR(vendor_id);
	CODEC_ATTR(subsystem_id);
	CODEC_ATTR(revision_id);
	CODEC_ATTR(afg);
	CODEC_ATTR(mfg);
	CODEC_ATTR_STR(vendor_name);
	CODEC_ATTR_STR(chip_name);

	static ssize_t modalias_show(struct device dev, struct device_attribute attr,
	char *buf)
	{
	return snd_hdac_codec_modalias(dev_to_hdac_dev(dev), buf, 256);
	}
	static DEVICE_ATTR_RO(modalias);

	static struct attribute *hdac_dev_attrs[] = {
	&dev_attr_type.attr,
	&dev_attr_vendor_id.attr,
	&dev_attr_subsystem_id.attr,
	&dev_attr_revision_id.attr,
	&dev_attr_afg.attr,
	&dev_attr_mfg.attr,
	&dev_attr_vendor_name.attr,
	&dev_attr_chip_name.attr,
	&dev_attr_modalias.attr,
	NULL
	};

	static const struct attribute_group hdac_dev_attr_group = {
	.attrs = hdac_dev_attrs,
	};

	const struct attribute_group *hdac_dev_attr_groups[] = {
	&hdac_dev_attr_group,
	NULL
	};

	/*
	* Widget tree sysfs
	*
	* This is a tree showing the attributes of each widget. It appears like
	* /sys/bus/hdaudioC0D0/widgets/04/caps
	*/

	struct widget_attribute;

	struct widget_attribute {
	struct attribute attr;
	ssize_t (show)(struct hdac_device codec, hda_nid_t nid,
	struct widget_attribute attr, char buf);
	ssize_t (store)(struct hdac_device codec, hda_nid_t nid,
	struct widget_attribute *attr,
	const char *buf, size_t count);
	};

	static int get_codec_nid(struct kobject kobj, struct hdac_device *codecp)
	{
	struct device *dev = kobj_to_dev(kobj->parent->parent);
	int nid;
	ssize_t ret;

	ret = kstrtoint(kobj->name, 16, &nid);
	if (ret < 0)
	return ret;
	*codecp = dev_to_hdac_dev(dev);
	return nid;
	}

	static ssize_t widget_attr_show(struct kobject kobj, struct attribute attr,
	char *buf)
	{
	struct widget_attribute *wid_attr =
	container_of(attr, struct widget_attribute, attr);
	struct hdac_device *codec;
	int nid;

	if (!wid_attr->show)
	return -EIO;
	nid = get_codec_nid(kobj, &codec);
	if (nid < 0)
	return nid;
	return wid_attr->show(codec, nid, wid_attr, buf);
	}

	static ssize_t widget_attr_store(struct kobject kobj, struct attribute attr,
	const char *buf, size_t count)
	{
	struct widget_attribute *wid_attr =
	container_of(attr, struct widget_attribute, attr);
	struct hdac_device *codec;
	int nid;

	if (!wid_attr->store)
	return -EIO;
	nid = get_codec_nid(kobj, &codec);
	if (nid < 0)
	return nid;
	return wid_attr->store(codec, nid, wid_attr, buf, count);
	}

	static const struct sysfs_ops widget_sysfs_ops = {
	.show = widget_attr_show,
	.store = widget_attr_store,
	};

	static void widget_release(struct kobject *kobj)
	{
	kfree(kobj);
	}

	static const struct kobj_type widget_ktype = {
	.release = widget_release,
	.sysfs_ops = &widget_sysfs_ops,
	};

	#define WIDGET_ATTR_RO(_name) \
	struct widget_attribute wid_attr_##_name = __ATTR_RO(_name)
	#define WIDGET_ATTR_RW(_name) \
	struct widget_attribute wid_attr_##_name = __ATTR_RW(_name)

	static ssize_t caps_show(struct hdac_device *codec, hda_nid_t nid,
	struct widget_attribute attr, char buf)
	{
	return sysfs_emit(buf, "0x%08x\n", get_wcaps(codec, nid));
	}

	static ssize_t pin_caps_show(struct hdac_device *codec, hda_nid_t nid,
	struct widget_attribute attr, char buf)
	{
	if (get_wcaps_type(get_wcaps(codec, nid)) != AC_WID_PIN)
	return 0;
	return sysfs_emit(buf, "0x%08x\n",
	snd_hdac_read_parm(codec, nid, AC_PAR_PIN_CAP));
	}

	static ssize_t pin_cfg_show(struct hdac_device *codec, hda_nid_t nid,
	struct widget_attribute attr, char buf)
	{
	unsigned int val;

	if (get_wcaps_type(get_wcaps(codec, nid)) != AC_WID_PIN)
	return 0;
	if (snd_hdac_read(codec, nid, AC_VERB_GET_CONFIG_DEFAULT, 0, &val))
	return 0;
	return sysfs_emit(buf, "0x%08x\n", val);
	}

	static bool has_pcm_cap(struct hdac_device *codec, hda_nid_t nid)
	{
	if (nid == codec->afg \|\| nid == codec->mfg)
	return true;
	switch (get_wcaps_type(get_wcaps(codec, nid))) {
	case AC_WID_AUD_OUT:
	case AC_WID_AUD_IN:
	return true;
	default:
	return false;
	}
	}

	static ssize_t pcm_caps_show(struct hdac_device *codec, hda_nid_t nid,
	struct widget_attribute attr, char buf)
	{
	if (!has_pcm_cap(codec, nid))
	return 0;
	return sysfs_emit(buf, "0x%08x\n",
	snd_hdac_read_parm(codec, nid, AC_PAR_PCM));
	}

	static ssize_t pcm_formats_show(struct hdac_device *codec, hda_nid_t nid,
	struct widget_attribute attr, char buf)
	{
	if (!has_pcm_cap(codec, nid))
	return 0;
	return sysfs_emit(buf, "0x%08x\n",
	snd_hdac_read_parm(codec, nid, AC_PAR_STREAM));
	}

	static ssize_t amp_in_caps_show(struct hdac_device *codec, hda_nid_t nid,
	struct widget_attribute attr, char buf)
	{
	if (nid != codec->afg && !(get_wcaps(codec, nid) & AC_WCAP_IN_AMP))
	return 0;
	return sysfs_emit(buf, "0x%08x\n",
	snd_hdac_read_parm(codec, nid, AC_PAR_AMP_IN_CAP));
	}

	static ssize_t amp_out_caps_show(struct hdac_device *codec, hda_nid_t nid,
	struct widget_attribute attr, char buf)
	{
	if (nid != codec->afg && !(get_wcaps(codec, nid) & AC_WCAP_OUT_AMP))
	return 0;
	return sysfs_emit(buf, "0x%08x\n",
	snd_hdac_read_parm(codec, nid, AC_PAR_AMP_OUT_CAP));
	}

	static ssize_t power_caps_show(struct hdac_device *codec, hda_nid_t nid,
	struct widget_attribute attr, char buf)
	{
	if (nid != codec->afg && !(get_wcaps(codec, nid) & AC_WCAP_POWER))
	return 0;
	return sysfs_emit(buf, "0x%08x\n",
	snd_hdac_read_parm(codec, nid, AC_PAR_POWER_STATE));
	}

	static ssize_t gpio_caps_show(struct hdac_device *codec, hda_nid_t nid,
	struct widget_attribute attr, char buf)
	{
	return sysfs_emit(buf, "0x%08x\n",
	snd_hdac_read_parm(codec, nid, AC_PAR_GPIO_CAP));
	}

	static ssize_t connections_show(struct hdac_device *codec, hda_nid_t nid,
	struct widget_attribute attr, char buf)
	{
	hda_nid_t list[32];
	int i, nconns;
	ssize_t ret = 0;

	nconns = snd_hdac_get_connections(codec, nid, list, ARRAY_SIZE(list));
	if (nconns <= 0)
	return nconns;
	for (i = 0; i < nconns; i++)
	ret += sysfs_emit_at(buf, ret, "%s0x%02x", i ? " " : "", list[i]);
	ret += sysfs_emit_at(buf, ret, "\n");
	return ret;
	}

	static WIDGET_ATTR_RO(caps);
	static WIDGET_ATTR_RO(pin_caps);
	static WIDGET_ATTR_RO(pin_cfg);
	static WIDGET_ATTR_RO(pcm_caps);
	static WIDGET_ATTR_RO(pcm_formats);
	static WIDGET_ATTR_RO(amp_in_caps);
	static WIDGET_ATTR_RO(amp_out_caps);
	static WIDGET_ATTR_RO(power_caps);
	static WIDGET_ATTR_RO(gpio_caps);
	static WIDGET_ATTR_RO(connections);

	static struct attribute *widget_node_attrs[] = {
	&wid_attr_caps.attr,
	&wid_attr_pin_caps.attr,
	&wid_attr_pin_cfg.attr,
	&wid_attr_pcm_caps.attr,
	&wid_attr_pcm_formats.attr,
	&wid_attr_amp_in_caps.attr,
	&wid_attr_amp_out_caps.attr,
	&wid_attr_power_caps.attr,
	&wid_attr_connections.attr,
	NULL,
	};

	static struct attribute *widget_afg_attrs[] = {
	&wid_attr_pcm_caps.attr,
	&wid_attr_pcm_formats.attr,
	&wid_attr_amp_in_caps.attr,
	&wid_attr_amp_out_caps.attr,
	&wid_attr_power_caps.attr,
	&wid_attr_gpio_caps.attr,
	NULL,
	};

	static const struct attribute_group widget_node_group = {
	.attrs = widget_node_attrs,
	};

	static const struct attribute_group widget_afg_group = {
	.attrs = widget_afg_attrs,
	};

	static void free_widget_node(struct kobject *kobj,
	const struct attribute_group *group)
	{
	if (kobj) {
	sysfs_remove_group(kobj, group);
	kobject_put(kobj);
	}
	}

	static void widget_tree_free(struct hdac_device *codec)
	{
	struct hdac_widget_tree *tree = codec->widgets;
	struct kobject **p;

	if (!tree)
	return;
	free_widget_node(tree->afg, &widget_afg_group);
	if (tree->nodes) {
	for (p = tree->nodes; *p; p++)
	free_widget_node(*p, &widget_node_group);
	kfree(tree->nodes);
	}
	kobject_put(tree->root);
	kfree(tree);
	codec->widgets = NULL;
	}

	static int add_widget_node(struct kobject *parent, hda_nid_t nid,
	const struct attribute_group *group,
	struct kobject **res)
	{
	struct kobject kobj = kzalloc(sizeof(kobj), GFP_KERNEL);
	int err;

	if (!kobj)
	return -ENOMEM;
	kobject_init(kobj, &widget_ktype);
	err = kobject_add(kobj, parent, "%02x", nid);
	if (err < 0) {
	kobject_put(kobj);
	return err;
	}
	err = sysfs_create_group(kobj, group);
	if (err < 0) {
	kobject_put(kobj);
	return err;
	}

	*res = kobj;
	return 0;
	}

	static int widget_tree_create(struct hdac_device *codec)
	{
	struct hdac_widget_tree *tree;
	int i, err;
	hda_nid_t nid;

	tree = codec->widgets = kzalloc(sizeof(*tree), GFP_KERNEL);
	if (!tree)
	return -ENOMEM;

	tree->root = kobject_create_and_add("widgets", &codec->dev.kobj);
	if (!tree->root)
	return -ENOMEM;

	tree->nodes = kcalloc(codec->num_nodes + 1, sizeof(*tree->nodes),
	GFP_KERNEL);
	if (!tree->nodes)
	return -ENOMEM;

	for (i = 0, nid = codec->start_nid; i < codec->num_nodes; i++, nid++) {
	err = add_widget_node(tree->root, nid, &widget_node_group,
	&tree->nodes[i]);
	if (err < 0)
	return err;
	}

	if (codec->afg) {
	err = add_widget_node(tree->root, codec->afg,
	&widget_afg_group, &tree->afg);
	if (err < 0)
	return err;
	}

	kobject_uevent(tree->root, KOBJ_CHANGE);
	return 0;
	}

	/* call with codec->widget_lock held */
	int hda_widget_sysfs_init(struct hdac_device *codec)
	{
	int err;

	if (codec->widgets)
	return 0; /* already created */

	err = widget_tree_create(codec);
	if (err < 0) {
	widget_tree_free(codec);
	return err;
	}

	return 0;
	}

	/* call with codec->widget_lock held */
	void hda_widget_sysfs_exit(struct hdac_device *codec)
	{
	widget_tree_free(codec);
	}

	/* call with codec->widget_lock held */
	int hda_widget_sysfs_reinit(struct hdac_device *codec,
	hda_nid_t start_nid, int num_nodes)
	{
	struct hdac_widget_tree *tree;
	hda_nid_t end_nid = start_nid + num_nodes;
	hda_nid_t nid;
	int i;

	if (!codec->widgets)
	return 0;

	tree = kmemdup(codec->widgets, sizeof(*tree), GFP_KERNEL);
	if (!tree)
	return -ENOMEM;

	tree->nodes = kcalloc(num_nodes + 1, sizeof(*tree->nodes), GFP_KERNEL);
	if (!tree->nodes) {
	kfree(tree);
	return -ENOMEM;
	}

	/* prune non-existing nodes */
	for (i = 0, nid = codec->start_nid; i < codec->num_nodes; i++, nid++) {
	if (nid < start_nid \|\| nid >= end_nid)
	free_widget_node(codec->widgets->nodes[i],
	&widget_node_group);
	}

	/* add new nodes */
	for (i = 0, nid = start_nid; i < num_nodes; i++, nid++) {
	if (nid < codec->start_nid \|\| nid >= codec->end_nid)
	add_widget_node(tree->root, nid, &widget_node_group,
	&tree->nodes[i]);
	else
	tree->nodes[i] =
	codec->widgets->nodes[nid - codec->start_nid];
	}

	/* replace with the new tree */
	kfree(codec->widgets->nodes);
	kfree(codec->widgets);
	codec->widgets = tree;

	kobject_uevent(tree->root, KOBJ_CHANGE);
	return 0;
	}