[RFC][PATCH v5 0/2] audio jack software injection

[RFC][PATCH v5 0/2] audio jack software injection

[Hui Wang]

the changes in the v5:
 - add a Kconfig to enable/disable the jack injection feature
 - replace all kzalloc with local char[] in the debugfs fops
 - replace the chars of !isalnum() to '_' for the jack folder's name
 - squash all .c files patches into one patch
 - add a document to explain jack injection, for easier review, put
   the document in a standalone patch. If needed, will squash this
   patch to the previous one.
 

the changes in the v4:
 - change the sound-core to sound and change the sound_core_debugfs_root
   to sound_debugfs_root in the 0001-xxx.patch
 - change kzalloc/kfree to kvzalloc/kvfree in the debugfs fops for
   0001-xxx.patch and 0003-xxx.patch
 - And if needed, I could squash 4 patches into 1 patch before merging.

the changes in the v3 (for easy to review, divide change into 4 patches):
 - address the comment about the snd_jack_report() and _snd_jack_report(),
   the v2 design is hard to understand and is hard to review, in the v3,
   separate the jack_report to snd_jack_report() and snd_jack_inject_report(),
   hw jack events call snd_jack_report() as before, if a jack contains multi
   jack_kctl and the jack_kctl's sw_inject is enabled, the status and the
   related input-dev's events will not be reproted. The injection events call
   snd_jack_inject_report(). This change is squashed to 0001-xxx.patch,  the
   rest part of 0001-xxx.patch is same as v2.

 - address the comment about folders'name in the 0002-xxx.patch, so far, drop
   the '/', ',', '=' and ' ' from the folders' name.

 - address the comment about adding more debugfs nodes in the 0003-xxx.patch,
   it adds kctl_id, mask_bits, status and type.

 - address the comment about save-n-restore jack's hw status in the
   0004-xxx.patch, adding a hw_status_cache and save the last reported jack
   hw event, once the sw_inject is disabled, will restore all jack_kctl's
   state under the same snd_jack with hw_status_cache.
[snip]


the changes in the V2:
 - using debugfs instead of sysfs
 - using jack_ctrl to create a folder instead of snd_jack, since ASoC drivers
   could create multi jack_ctrls within a snd_jack
 - create a folder for each jack_ctrl instead for all jack_ctrls
[ snip ]


Hui Wang (2):
  alsa: jack: implement software jack injection via debugfs
  alsa: jack: add document for sound jack injection.

 Documentation/sound/designs/index.rst         |   1 +
 .../sound/designs/jack-injection.rst          | 124 ++++++++
 include/sound/core.h                          |   2 +
 include/sound/jack.h                          |   1 +
 sound/core/Kconfig                            |   9 +
 sound/core/init.c                             |  10 +
 sound/core/jack.c                             | 298 +++++++++++++++++-
 sound/core/sound.c                            |   8 +
 8 files changed, 449 insertions(+), 4 deletions(-)
 create mode 100644 Documentation/sound/designs/jack-injection.rst

-- 
2.25.1

[RFC][PATCH v5 1/2] alsa: jack: implement software jack injection via debugfs

[Hui Wang]

This change adds audio jack injection feature through debugfs, with
this feature, we could validate alsa userspace changes by injecting
plugin or plugout events to the non-phantom audio jacks.

With this change, the sound core will build the folders
$debugfs_mount_dir/sound/cardN if DEBUG_FS is enabled. And if users
also enable the SND_JACK_INJECTION_DEBUG, the jack injection nodes
will be built in the folder cardN like below:

$tree $debugfs_mount_dir/sound
$debugfs_mount_dir/sound
├── card0
│   ├── HDMI_DP_pcm_10_Jack
│   │   ├── jackin_inject
│   │   ├── kctl_id
│   │   ├── mask_bits
│   │   ├── status
│   │   ├── sw_inject_enable
│   │   └── type
...
│   └── HDMI_DP_pcm_9_Jack
│       ├── jackin_inject
│       ├── kctl_id
│       ├── mask_bits
│       ├── status
│       ├── sw_inject_enable
│       └── type
└── card1
    ├── HDMI_DP_pcm_5_Jack
    │   ├── jackin_inject
    │   ├── kctl_id
    │   ├── mask_bits
    │   ├── status
    │   ├── sw_inject_enable
    │   └── type
    ...
    ├── Headphone_Jack
    │   ├── jackin_inject
    │   ├── kctl_id
    │   ├── mask_bits
    │   ├── status
    │   ├── sw_inject_enable
    │   └── type
    └── Headset_Mic_Jack
        ├── jackin_inject
        ├── kctl_id
        ├── mask_bits
        ├── status
        ├── sw_inject_enable
        └── type

The nodes kctl_id, mask_bits, status and type are read-only, users
could check jack or jack_kctl's information through them.

The nodes sw_inject_enable and jackin_inject are directly used for
injection. The sw_inject_enable is read-write, users could check if
software injection is enabled or not on this jack, and users could
echo 1 or 0 to enable or disable software injection on this jack. Once
the injection is enabled, the jack will not change by hardware events
anymore, once the injection is disabled, the jack will restore the
last reported hardware events to the jack. The jackin_inject is
write-only, if the injection is enabled, users could echo 1 or 0 to
this node to inject plugin or plugout events to this jack.

For the detailed usage information on these nodes, please refer to
Documentation/sound/designs/jack-injection.rst.

Reviewed-by: Takashi Iwai <tiwai@suse.de>
Reviewed-by: Jaroslav Kysela <perex@perex.cz>
Reviewed-by: Kai Vehmanen <kai.vehmanen@linux.intel.com>
Signed-off-by: Hui Wang <hui.wang@canonical.com>
---
 include/sound/core.h |   2 +
 include/sound/jack.h |   1 +
 sound/core/Kconfig   |   9 ++
 sound/core/init.c    |  10 ++
 sound/core/jack.c    | 298 ++++++++++++++++++++++++++++++++++++++++++-
 sound/core/sound.c   |   8 ++
 6 files changed, 324 insertions(+), 4 deletions(-)

diff --git a/include/sound/core.h b/include/sound/core.h
index 0462c577d7a3..15175fd44971 100644
--- a/include/sound/core.h
+++ b/include/sound/core.h
@@ -122,6 +122,7 @@ struct snd_card {
 
 	size_t total_pcm_alloc_bytes;	/* total amount of allocated buffers */
 	struct mutex memory_mutex;	/* protection for the above */
+	struct dentry *debugfs_root;    /* debugfs root for card */
 
 #ifdef CONFIG_PM
 	unsigned int power_state;	/* power state */
@@ -180,6 +181,7 @@ static inline struct device *snd_card_get_device_link(struct snd_card *card)
 extern int snd_major;
 extern int snd_ecards_limit;
 extern struct class *sound_class;
+extern struct dentry *sound_debugfs_root;
 
 void snd_request_card(int card);
 
diff --git a/include/sound/jack.h b/include/sound/jack.h
index 9eb2b5ec1ec4..1181f536557e 100644
--- a/include/sound/jack.h
+++ b/include/sound/jack.h
@@ -67,6 +67,7 @@ struct snd_jack {
 	char name[100];
 	unsigned int key[6];   /* Keep in sync with definitions above */
 #endif /* CONFIG_SND_JACK_INPUT_DEV */
+	int hw_status_cache;
 	void *private_data;
 	void (*private_free)(struct snd_jack *);
 };
diff --git a/sound/core/Kconfig b/sound/core/Kconfig
index d4554f376160..a9189f58dc56 100644
--- a/sound/core/Kconfig
+++ b/sound/core/Kconfig
@@ -38,6 +38,15 @@ config SND_JACK_INPUT_DEV
 	depends on SND_JACK
 	default y if INPUT=y || INPUT=SND
 
+config SND_JACK_INJECTION_DEBUG
+	bool "Sound jack injection interface via debugfs"
+	depends on SND_JACK && DEBUG_FS
+	help
+	  This option can be used to enable or disable sound jack
+	  software injection.
+	  Say Y if you are debugging via jack injection interface.
+	  If unsure select "N".
+
 config SND_OSSEMUL
 	bool "Enable OSS Emulation"
 	select SOUND_OSS_CORE
diff --git a/sound/core/init.c b/sound/core/init.c
index 75aec71c48a8..e7f7cfe1143b 100644
--- a/sound/core/init.c
+++ b/sound/core/init.c
@@ -13,6 +13,7 @@
 #include <linux/time.h>
 #include <linux/ctype.h>
 #include <linux/pm.h>
+#include <linux/debugfs.h>
 #include <linux/completion.h>
 
 #include <sound/core.h>
@@ -161,6 +162,7 @@ int snd_card_new(struct device *parent, int idx, const char *xid,
 {
 	struct snd_card *card;
 	int err;
+	char name[8];
 
 	if (snd_BUG_ON(!card_ret))
 		return -EINVAL;
@@ -244,6 +246,10 @@ int snd_card_new(struct device *parent, int idx, const char *xid,
 		dev_err(parent, "unable to create card info\n");
 		goto __error_ctl;
 	}
+
+	sprintf(name, "card%d", idx);
+	card->debugfs_root = debugfs_create_dir(name, sound_debugfs_root);
+
 	*card_ret = card;
 	return 0;
 
@@ -526,6 +532,10 @@ int snd_card_free(struct snd_card *card)
 		return ret;
 	/* wait, until all devices are ready for the free operation */
 	wait_for_completion(&released);
+
+	debugfs_remove(card->debugfs_root);
+	card->debugfs_root = NULL;
+
 	return 0;
 }
 EXPORT_SYMBOL(snd_card_free);
diff --git a/sound/core/jack.c b/sound/core/jack.c
index 503c8af79d55..ae4208210d78 100644
--- a/sound/core/jack.c
+++ b/sound/core/jack.c
@@ -8,6 +8,9 @@
 #include <linux/input.h>
 #include <linux/slab.h>
 #include <linux/module.h>
+#include <linux/ctype.h>
+#include <linux/mm.h>
+#include <linux/debugfs.h>
 #include <sound/jack.h>
 #include <sound/core.h>
 #include <sound/control.h>
@@ -16,6 +19,9 @@ struct snd_jack_kctl {
 	struct snd_kcontrol *kctl;
 	struct list_head list;  /* list of controls belong to the same jack */
 	unsigned int mask_bits; /* only masked status bits are reported via kctl */
+	struct snd_jack *jack;  /* pointer to struct snd_jack */
+	bool sw_inject_enable;  /* allow to inject plug event via debugfs */
+	struct dentry *jack_debugfs_root; /* jack_kctl debugfs root */
 };
 
 #ifdef CONFIG_SND_JACK_INPUT_DEV
@@ -109,12 +115,286 @@ static int snd_jack_dev_register(struct snd_device *device)
 }
 #endif /* CONFIG_SND_JACK_INPUT_DEV */
 
+#ifdef CONFIG_SND_JACK_INJECTION_DEBUG
+static void snd_jack_inject_report(struct snd_jack_kctl *jack_kctl, int status)
+{
+	struct snd_jack *jack;
+#ifdef CONFIG_SND_JACK_INPUT_DEV
+	int i;
+#endif
+	if (!jack_kctl)
+		return;
+
+	jack = jack_kctl->jack;
+
+	if (jack_kctl->sw_inject_enable)
+		snd_kctl_jack_report(jack->card, jack_kctl->kctl,
+				     status & jack_kctl->mask_bits);
+
+#ifdef CONFIG_SND_JACK_INPUT_DEV
+	if (!jack->input_dev)
+		return;
+
+	for (i = 0; i < ARRAY_SIZE(jack->key); i++) {
+		int testbit = ((SND_JACK_BTN_0 >> i) & jack_kctl->mask_bits);
+
+		if (jack->type & testbit)
+			input_report_key(jack->input_dev, jack->key[i],
+					 status & testbit);
+	}
+
+	for (i = 0; i < ARRAY_SIZE(jack_switch_types); i++) {
+		int testbit = ((1 << i) & jack_kctl->mask_bits);
+
+		if (jack->type & testbit)
+			input_report_switch(jack->input_dev,
+					    jack_switch_types[i],
+					    status & testbit);
+	}
+
+	input_sync(jack->input_dev);
+#endif /* CONFIG_SND_JACK_INPUT_DEV */
+}
+
+static ssize_t sw_inject_enable_read(struct file *file,
+				     char __user *to, size_t count, loff_t *ppos)
+{
+	struct snd_jack_kctl *jack_kctl = file->private_data;
+	int len, ret;
+	char buf[128];
+
+	len = scnprintf(buf, 128, "%s: %s\t\t%s: %i\n", "Jack", jack_kctl->kctl->id.name,
+			"Inject Enabled", jack_kctl->sw_inject_enable);
+	ret = simple_read_from_buffer(to, count, ppos, buf, len);
+
+	return ret;
+}
+
+static ssize_t sw_inject_enable_write(struct file *file,
+				      const char __user *from, size_t count, loff_t *ppos)
+{
+	struct snd_jack_kctl *jack_kctl = file->private_data;
+	int ret, err;
+	unsigned long enable;
+	char buf[8] = { 0 };
+
+	if (count >= 8)
+		return -EINVAL;
+
+	ret = simple_write_to_buffer(buf, count, ppos, from, count);
+	err = kstrtoul(buf, 0, &enable);
+	if (err)
+		return err;
+
+	if (jack_kctl->sw_inject_enable == (!!enable))
+		return ret;
+
+	jack_kctl->sw_inject_enable = !!enable;
+
+	if (!jack_kctl->sw_inject_enable)
+		snd_jack_report(jack_kctl->jack, jack_kctl->jack->hw_status_cache);
+
+	return ret;
+}
+
+static ssize_t jackin_inject_write(struct file *file,
+				   const char __user *from, size_t count, loff_t *ppos)
+{
+	struct snd_jack_kctl *jack_kctl = file->private_data;
+	int ret, err;
+	unsigned long enable;
+	char buf[8] = { 0 };
+
+	if (!jack_kctl->sw_inject_enable)
+		return -EINVAL;
+
+	if (count >= 8)
+		return -EINVAL;
+
+	ret = simple_write_to_buffer(buf, count, ppos, from, count);
+	err = kstrtoul(buf, 0, &enable);
+	if (err)
+		return err;
+
+	snd_jack_inject_report(jack_kctl, !!enable ? jack_kctl->mask_bits : 0);
+
+	return ret;
+}
+
+static ssize_t jack_kctl_id_read(struct file *file,
+				 char __user *to, size_t count, loff_t *ppos)
+{
+	struct snd_jack_kctl *jack_kctl = file->private_data;
+	char buf[64];
+	int len, ret;
+
+	len = scnprintf(buf, 64, "%s\n", jack_kctl->kctl->id.name);
+	ret = simple_read_from_buffer(to, count, ppos, buf, len);
+
+	return ret;
+}
+
+/* the bit definition is aligned with snd_jack_types in jack.h */
+static const char * const jack_events_name[] = {
+	"HEADPHONE(0x0001)", "MICROPHONE(0x0002)", "LINEOUT(0x0004)",
+	"MECHANICAL(0x0008)", "VIDEOOUT(0x0010)", "LINEIN(0x0020)",
+	"", "", "", "BTN_5(0x0200)", "BTN_4(0x0400)", "BTN_3(0x0800)",
+	"BTN_2(0x1000)", "BTN_1(0x2000)", "BTN_0(0x4000)", "",
+};
+
+static int parse_mask_bits(unsigned int mask_bits, char *s)
+{
+	char buf[256];
+	int len, i;
+
+	len = scnprintf(buf, 256, "0x%04x", mask_bits);
+
+	for (i = 0; i < 16; i++)
+		if (mask_bits & (1 << i))
+			len += scnprintf(buf + strlen(buf), 256 - strlen(buf),
+					 " %s", jack_events_name[i]);
+
+	len += scnprintf(buf + strlen(buf), 256 - strlen(buf), "\n");
+
+	strcpy(s, buf);
+
+	return len;
+}
+
+static ssize_t jack_kctl_mask_bits_read(struct file *file,
+					char __user *to, size_t count, loff_t *ppos)
+{
+	struct snd_jack_kctl *jack_kctl = file->private_data;
+	char buf[256];
+	int len, ret;
+
+	len = parse_mask_bits(jack_kctl->mask_bits, buf);
+	ret = simple_read_from_buffer(to, count, ppos, buf, len);
+
+	return ret;
+}
+
+static ssize_t jack_kctl_status_read(struct file *file,
+				     char __user *to, size_t count, loff_t *ppos)
+{
+	struct snd_jack_kctl *jack_kctl = file->private_data;
+	char buf[16];
+	int len, ret;
+
+	len = scnprintf(buf, 16, "%s\n", jack_kctl->kctl->private_value ?
+			"Plugged" : "Unplugged");
+	ret = simple_read_from_buffer(to, count, ppos, buf, len);
+
+	return ret;
+}
+
+#ifdef CONFIG_SND_JACK_INPUT_DEV
+static ssize_t jack_type_read(struct file *file,
+			      char __user *to, size_t count, loff_t *ppos)
+{
+	struct snd_jack_kctl *jack_kctl = file->private_data;
+	char buf[256];
+	int len, ret;
+
+	len = parse_mask_bits(jack_kctl->jack->type, buf);
+	ret = simple_read_from_buffer(to, count, ppos, buf, len);
+
+	return ret;
+}
+
+static const struct file_operations jack_type_fops = {
+	.open = simple_open,
+	.read = jack_type_read,
+	.llseek = default_llseek,
+};
+#endif
+
+static const struct file_operations sw_inject_enable_fops = {
+	.open = simple_open,
+	.read = sw_inject_enable_read,
+	.write = sw_inject_enable_write,
+	.llseek = default_llseek,
+};
+
+static const struct file_operations jackin_inject_fops = {
+	.open = simple_open,
+	.write = jackin_inject_write,
+	.llseek = default_llseek,
+};
+
+static const struct file_operations jack_kctl_id_fops = {
+	.open = simple_open,
+	.read = jack_kctl_id_read,
+	.llseek = default_llseek,
+};
+
+static const struct file_operations jack_kctl_mask_bits_fops = {
+	.open = simple_open,
+	.read = jack_kctl_mask_bits_read,
+	.llseek = default_llseek,
+};
+
+static const struct file_operations jack_kctl_status_fops = {
+	.open = simple_open,
+	.read = jack_kctl_status_read,
+	.llseek = default_llseek,
+};
+
+static int snd_jack_debugfs_add_inject_node(struct snd_jack *jack,
+					    struct snd_jack_kctl *jack_kctl)
+{
+	char *tname;
+	int i;
+
+	tname = kstrdup(jack_kctl->kctl->id.name, GFP_KERNEL);
+	if (!tname)
+		return -ENOMEM;
+
+	/* replace the chars which are not suitable for folder's name with _ */
+	for (i = 0; i < strlen(tname); i++)
+		if (!isalnum(tname[i]))
+			tname[i] = '_';
+
+	jack_kctl->jack_debugfs_root = debugfs_create_dir(tname, jack->card->debugfs_root);
+	kfree(tname);
+
+	debugfs_create_file("sw_inject_enable", 0644, jack_kctl->jack_debugfs_root, jack_kctl,
+			    &sw_inject_enable_fops);
+
+	debugfs_create_file("jackin_inject", 0200, jack_kctl->jack_debugfs_root, jack_kctl,
+			    &jackin_inject_fops);
+
+	debugfs_create_file("kctl_id", 0444, jack_kctl->jack_debugfs_root, jack_kctl,
+			    &jack_kctl_id_fops);
+
+	debugfs_create_file("mask_bits", 0444, jack_kctl->jack_debugfs_root, jack_kctl,
+			    &jack_kctl_mask_bits_fops);
+
+	debugfs_create_file("status", 0444, jack_kctl->jack_debugfs_root, jack_kctl,
+			    &jack_kctl_status_fops);
+
+#ifdef CONFIG_SND_JACK_INPUT_DEV
+	debugfs_create_file("type", 0444, jack_kctl->jack_debugfs_root, jack_kctl,
+			    &jack_type_fops);
+#endif
+	return 0;
+}
+#else /* CONFIG_SND_JACK_INJECTION_DEBUG */
+static int snd_jack_debugfs_add_inject_node(struct snd_jack *jack,
+					    struct snd_jack_kctl *jack_kctl)
+{
+	return 0;
+}
+#endif /* CONFIG_SND_JACK_INJECTION_DEBUG */
+
 static void snd_jack_kctl_private_free(struct snd_kcontrol *kctl)
 {
 	struct snd_jack_kctl *jack_kctl;
 
 	jack_kctl = kctl->private_data;
 	if (jack_kctl) {
+		debugfs_remove(jack_kctl->jack_debugfs_root);
+		jack_kctl->jack_debugfs_root = NULL;
 		list_del(&jack_kctl->list);
 		kfree(jack_kctl);
 	}
@@ -122,7 +402,10 @@ static void snd_jack_kctl_private_free(struct snd_kcontrol *kctl)
 
 static void snd_jack_kctl_add(struct snd_jack *jack, struct snd_jack_kctl *jack_kctl)
 {
+	jack_kctl->jack = jack;
 	list_add_tail(&jack_kctl->list, &jack->kctl_list);
+	if (!strstr(jack_kctl->kctl->id.name, "Phantom"))
+		snd_jack_debugfs_add_inject_node(jack, jack_kctl);
 }
 
 static struct snd_jack_kctl * snd_jack_kctl_new(struct snd_card *card, const char *name, unsigned int mask)
@@ -340,6 +623,7 @@ EXPORT_SYMBOL(snd_jack_set_key);
 void snd_jack_report(struct snd_jack *jack, int status)
 {
 	struct snd_jack_kctl *jack_kctl;
+	unsigned int mask_bits = 0;
 #ifdef CONFIG_SND_JACK_INPUT_DEV
 	int i;
 #endif
@@ -347,16 +631,21 @@ void snd_jack_report(struct snd_jack *jack, int status)
 	if (!jack)
 		return;
 
+	jack->hw_status_cache = status;
+
 	list_for_each_entry(jack_kctl, &jack->kctl_list, list)
-		snd_kctl_jack_report(jack->card, jack_kctl->kctl,
-					    status & jack_kctl->mask_bits);
+		if (jack_kctl->sw_inject_enable)
+			mask_bits |= jack_kctl->mask_bits;
+		else
+			snd_kctl_jack_report(jack->card, jack_kctl->kctl,
+					     status & jack_kctl->mask_bits);
 
 #ifdef CONFIG_SND_JACK_INPUT_DEV
 	if (!jack->input_dev)
 		return;
 
 	for (i = 0; i < ARRAY_SIZE(jack->key); i++) {
-		int testbit = SND_JACK_BTN_0 >> i;
+		int testbit = ((SND_JACK_BTN_0 >> i) & ~mask_bits);
 
 		if (jack->type & testbit)
 			input_report_key(jack->input_dev, jack->key[i],
@@ -364,7 +653,8 @@ void snd_jack_report(struct snd_jack *jack, int status)
 	}
 
 	for (i = 0; i < ARRAY_SIZE(jack_switch_types); i++) {
-		int testbit = 1 << i;
+		int testbit = ((1 << i) & ~mask_bits);
+
 		if (jack->type & testbit)
 			input_report_switch(jack->input_dev,
 					    jack_switch_types[i],
diff --git a/sound/core/sound.c b/sound/core/sound.c
index b75f78f2c4b8..8a80f0440455 100644
--- a/sound/core/sound.c
+++ b/sound/core/sound.c
@@ -9,6 +9,7 @@
 #include <linux/time.h>
 #include <linux/device.h>
 #include <linux/module.h>
+#include <linux/debugfs.h>
 #include <sound/core.h>
 #include <sound/minors.h>
 #include <sound/info.h>
@@ -39,6 +40,9 @@ MODULE_ALIAS_CHARDEV_MAJOR(CONFIG_SND_MAJOR);
 int snd_ecards_limit;
 EXPORT_SYMBOL(snd_ecards_limit);
 
+struct dentry *sound_debugfs_root;
+EXPORT_SYMBOL_GPL(sound_debugfs_root);
+
 static struct snd_minor *snd_minors[SNDRV_OS_MINORS];
 static DEFINE_MUTEX(sound_mutex);
 
@@ -395,6 +399,9 @@ static int __init alsa_sound_init(void)
 		unregister_chrdev(major, "alsa");
 		return -ENOMEM;
 	}
+
+	sound_debugfs_root = debugfs_create_dir("sound", NULL);
+
 #ifndef MODULE
 	pr_info("Advanced Linux Sound Architecture Driver Initialized.\n");
 #endif
@@ -403,6 +410,7 @@ static int __init alsa_sound_init(void)
 
 static void __exit alsa_sound_exit(void)
 {
+	debugfs_remove(sound_debugfs_root);
 	snd_info_done();
 	unregister_chrdev(major, "alsa");
 }
-- 
2.25.1

[RFC][PATCH v5 2/2] alsa: jack: add document for sound jack injection.

[Hui Wang]

Reviewed-by: Takashi Iwai <tiwai@suse.de>
Reviewed-by: Jaroslav Kysela <perex@perex.cz>
Reviewed-by: Kai Vehmanen <kai.vehmanen@linux.intel.com>
Signed-off-by: Hui Wang <hui.wang@canonical.com>
---
 Documentation/sound/designs/index.rst         |   1 +
 .../sound/designs/jack-injection.rst          | 124 ++++++++++++++++++
 2 files changed, 125 insertions(+)
 create mode 100644 Documentation/sound/designs/jack-injection.rst

diff --git a/Documentation/sound/designs/index.rst b/Documentation/sound/designs/index.rst
index f0749943ccb2..1eb08e7bae52 100644
--- a/Documentation/sound/designs/index.rst
+++ b/Documentation/sound/designs/index.rst
@@ -14,3 +14,4 @@ Designs and Implementations
    powersave
    oss-emulation
    seq-oss
+   jack-injection
diff --git a/Documentation/sound/designs/jack-injection.rst b/Documentation/sound/designs/jack-injection.rst
new file mode 100644
index 000000000000..0915048a0dbd
--- /dev/null
+++ b/Documentation/sound/designs/jack-injection.rst
@@ -0,0 +1,124 @@
+============================
+ALSA Jack Software Injection
+============================
+
+Simple Introduction On Jack Injection
+=====================================
+
+Here jack injection means users could inject plugin or plugout events
+to the audio jacks through debugfs interface, it is helpful to
+validate ALSA userspace changes. For example, we change the audio
+profile switching code in the pulseaudio, and we want to verify if the
+change works as expected and if the change introduce the regression,
+in this case, we could inject plugin or plugout events to an audio
+jack or to some audio jacks, we don't need to physically access the
+machine and plug/unplug physical devices to the audio jack.
+
+In this design, an audio jack doesn't equal to a physical audio jack.
+Sometimes a physical audio jack contains multi functions, and the
+ALSA driver creates multi ``jack_kctl`` for a ``snd_jack``, here the
+``snd_jack`` represents a physical audio jack and the ``jack_kctl``
+represents a function, for example a physical jack has two functions:
+headphone and mic_in, the ALSA ASoC driver will build 2 ``jack_kctl``
+for this jack. The jack injection is implemented based on the
+``jack_kctl`` instead of ``snd_jack``.
+
+To inject events to audio jacks, we need to enable the jack injection
+via ``sw_inject_enable`` first, once it is enabled, this jack will not
+change the state by hardware events anymore, we could inject plugin or
+plugout events via ``jackin_inject`` and check the jack state via
+``status``, after we finish our test, we need to disable the jack
+injection via ``sw_inject_enable`` too, once it is disabled, the jack
+state will be restored according to the last reported hardware events
+and will change by future hardware events.
+
+The Layout of Jack Injection Interface
+======================================
+
+If users enable the SND_JACK_INJECTION_DEBUG in the kernel, the audio
+jack injection interface will be created as below:
+::
+
+   $debugfs_mount_dir/sound
+   |-- card0
+   |-- |-- HDMI_DP_pcm_10_Jack
+   |-- |-- |-- jackin_inject
+   |-- |-- |-- kctl_id
+   |-- |-- |-- mask_bits
+   |-- |-- |-- status
+   |-- |-- |-- sw_inject_enable
+   |-- |-- |-- type
+   ...
+   |-- |-- HDMI_DP_pcm_9_Jack
+   |--     |-- jackin_inject
+   |--     |-- kctl_id
+   |--     |-- mask_bits
+   |--     |-- status
+   |--     |-- sw_inject_enable
+   |--     |-- type
+   |-- card1
+       |-- HDMI_DP_pcm_5_Jack
+       |-- |-- jackin_inject
+       |-- |-- kctl_id
+       |-- |-- mask_bits
+       |-- |-- status
+       |-- |-- sw_inject_enable
+       |-- |-- type
+       ...
+       |-- Headphone_Jack
+       |-- |-- jackin_inject
+       |-- |-- kctl_id
+       |-- |-- mask_bits
+       |-- |-- status
+       |-- |-- sw_inject_enable
+       |-- |-- type
+       |-- Headset_Mic_Jack
+           |-- jackin_inject
+           |-- kctl_id
+           |-- mask_bits
+           |-- status
+           |-- sw_inject_enable
+           |-- type
+
+
+Explanation for the debugfs nodes:
+::
+
+ - kctl_id, read-only, get jack_kctl->kctl's id
+   sound/card1/Headphone_Jack# cat kctl_id
+   Headphone Jack
+
+ - mask_bits, read-only, get jack_kctl's supported events mask_bits
+   sound/card1/Headphone_Jack# cat mask_bits
+   0x0001 HEADPHONE(0x0001)
+
+ - status, read-only, get jack_kctl's current status
+   headphone unplugged:
+   sound/card1/Headphone_Jack# cat status
+   Unplugged
+   headphone plugged:
+   sound/card1/Headphone_Jack# cat status
+   Plugged
+
+ - type, read-only, get snd_jack's supported events type (all
+   supported events on the physical audio jack)
+   sound/card1/Headphone_Jack# cat type
+   0x7803 HEADPHONE(0x0001) MICROPHONE(0x0002) BTN_3(0x0800) BTN_2(0x1000) BTN_1(0x2000) BTN_0(0x4000)
+
+ - sw_inject_enable, read-write, enable or disable injection
+   injection disabled:
+   sound/card1/Headphone_Jack# cat sw_inject_enable
+   Jack: Headphone Jack		Inject Enabled: 0
+   injection enabled:
+   sound/card1/Headphone_Jack# cat sw_inject_enable
+   Jack: Headphone Jack		Inject Enabled: 1
+   to enable jack injection:
+   sound/card1/Headphone_Jack# echo 1 > sw_inject_enable
+   to disable jack injection:
+   sound/card1/Headphone_Jack# echo 0 > sw_inject_enable
+
+ - jackin_inject, write-only, inject plugin or plugout
+   to inject plugin:
+   sound/card1/Headphone_Jack# echo 1 > jackin_inject
+   to inject plugout:
+   sound/card1/Headphone_Jack# echo 0 > jackin_inject
-- 
2.25.1

Re: [RFC][PATCH v5 1/2] alsa: jack: implement software jack injection via debugfs

[Jaroslav Kysela]

Dne 22. 01. 21 v 9:21 Hui Wang napsal(a):

> +	len = scnprintf(buf, 256, "0x%04x", mask_bits);

Use sizeof(buf) on all appropriate places. Also never use user space 'count'
variable for the stack buffer size.

				Jaroslav

-- 
Jaroslav Kysela <perex@perex.cz>
Linux Sound Maintainer; ALSA Project; Red Hat, Inc.

Re: [RFC][PATCH v5 1/2] alsa: jack: implement software jack injection via debugfs

[Hui Wang]

On 1/22/21 4:40 PM, Jaroslav Kysela wrote:
> Dne 22. 01. 21 v 9:21 Hui Wang napsal(a):
>
>> +	len = scnprintf(buf, 256, "0x%04x", mask_bits);
> Use sizeof(buf) on all appropriate places. Also never use user space 'count'
> variable for the stack buffer size.
>
> 				Jaroslav

Oh, right, will use sizeof(buf).  Will not use 'count' for stack buffer 
size.

Thanks,

Hui.

>