[PATCH] [PATCH v3] usb: gadget: f_uac2: uevent changes for uac2

[Akash Kumar]

Adding uevent from usb audio gadget driver for uac2 playback/capture
events, which userspace reads and later reads sysfs entry to know if
playback or capture has stopped or started by host application.

/config/usb_gadget/g1/functions/uac2.0 # cat c_status
1  --> capture started
0  --> capture stopped
/config/usb_gadget/g1/functions/uac2.0 # cat p_status
1 --> playback started
0 --> playback stopped

Signed-off-by: Akash Kumar <quic_akakum@xxxxxxxxxxx>
---
 Documentation/usb/gadget-testing.rst |  6 ++++
 drivers/usb/gadget/function/f_uac2.c | 47 ++++++++++++++++++++++++++++
 drivers/usb/gadget/function/u_uac2.h |  5 +++
 3 files changed, 58 insertions(+)

diff --git a/Documentation/usb/gadget-testing.rst b/Documentation/usb/gadget-testing.rst
index 2eeb3e9299e4..b2fded232ced 100644
--- a/Documentation/usb/gadget-testing.rst
+++ b/Documentation/usb/gadget-testing.rst
@@ -733,6 +733,12 @@ The uac2 function provides these attributes in its function directory:
 	p_ssize		playback sample size (bytes)
 	req_number	the number of pre-allocated request for both capture
 			and playback
+        c_status        audio capture state
+                        (0: capture stopped, 1: capture started)
+        p_status        audio playback state
+                        (0: playback stopped, 1: playback started)
+        c_status        audio capture state
+        p_status        audio playback state
 	=============== ====================================================
 
 The attributes have sane default values.
diff --git a/drivers/usb/gadget/function/f_uac2.c b/drivers/usb/gadget/function/f_uac2.c
index db2d4980cb35..f1f7631e9380 100644
--- a/drivers/usb/gadget/function/f_uac2.c
+++ b/drivers/usb/gadget/function/f_uac2.c
@@ -739,6 +739,8 @@ afunc_set_alt(struct usb_function *fn, unsigned intf, unsigned alt)
 	struct usb_gadget *gadget = cdev->gadget;
 	struct device *dev = &gadget->dev;
 	int ret = 0;
+	struct f_uac2_opts *audio_opts =
+		container_of(fn->fi, struct f_uac2_opts, func_inst);
 
 	/* No i/f has more than 2 alt settings */
 	if (alt > 1) {
@@ -762,6 +764,8 @@ afunc_set_alt(struct usb_function *fn, unsigned intf, unsigned alt)
 			ret = u_audio_start_capture(&uac2->g_audio);
 		else
 			u_audio_stop_capture(&uac2->g_audio);
+		audio_opts->c_status = alt;
+		schedule_work(&audio_opts->work);
 	} else if (intf == uac2->as_in_intf) {
 		uac2->as_in_alt = alt;
 
@@ -769,6 +773,8 @@ afunc_set_alt(struct usb_function *fn, unsigned intf, unsigned alt)
 			ret = u_audio_start_playback(&uac2->g_audio);
 		else
 			u_audio_stop_playback(&uac2->g_audio);
+		audio_opts->p_status = alt;
+		schedule_work(&audio_opts->work);
 	} else {
 		dev_err(dev, "%s:%d Error!\n", __func__, __LINE__);
 		return -EINVAL;
@@ -801,11 +807,16 @@ static void
 afunc_disable(struct usb_function *fn)
 {
 	struct f_uac2 *uac2 = func_to_uac2(fn);
+	struct f_uac2_opts *audio_opts =
+		container_of(fn->fi, struct f_uac2_opts, func_inst);
 
 	uac2->as_in_alt = 0;
 	uac2->as_out_alt = 0;
+	audio_opts->p_status = 0;//alt;
+	audio_opts->c_status = 0; //alt;
 	u_audio_stop_capture(&uac2->g_audio);
 	u_audio_stop_playback(&uac2->g_audio);
+	schedule_work(&audio_opts->work);
 }
 
 static int
@@ -1036,6 +1047,25 @@ UAC2_ATTRIBUTE(c_srate);
 UAC2_ATTRIBUTE(c_ssize);
 UAC2_ATTRIBUTE(req_number);
 
+#define UAC2_ATTRIBUTE_RO(name)                                         \
+	static ssize_t f_uac2_opts_##name##_show(                       \
+			struct config_item *item,                       \
+			char *page)                                     \
+{                                                                       \
+	struct f_uac2_opts *opts = to_f_uac2_opts(item);                \
+	int result;                                                     \
+									\
+	mutex_lock(&opts->lock);                                        \
+	result = scnprintf(page, PAGE_SIZE, "%u\n", opts->name);        \
+	mutex_unlock(&opts->lock);                                      \
+									\
+	return result;                                                  \
+}                                                                       \
+CONFIGFS_ATTR_RO(f_uac2_opts_, name)
+
+UAC2_ATTRIBUTE_RO(c_status);
+UAC2_ATTRIBUTE_RO(p_status);
+
 static struct configfs_attribute *f_uac2_attrs[] = {
 	&f_uac2_opts_attr_p_chmask,
 	&f_uac2_opts_attr_p_srate,
@@ -1044,6 +1074,8 @@ static struct configfs_attribute *f_uac2_attrs[] = {
 	&f_uac2_opts_attr_c_srate,
 	&f_uac2_opts_attr_c_ssize,
 	&f_uac2_opts_attr_req_number,
+	&f_uac2_opts_attr_c_status,
+	&f_uac2_opts_attr_p_status,
 	NULL,
 };
 
@@ -1053,11 +1085,23 @@ static const struct config_item_type f_uac2_func_type = {
 	.ct_owner	= THIS_MODULE,
 };
 
+static void f_uac2_audio_status_change_work(struct work_struct *data)
+{
+	struct f_uac2_opts *audio_opts =
+		container_of(data, struct f_uac2_opts, work);
+	char *envp[2] = { "UAC2_STATE=Changed", NULL };
+
+	kobject_uevent_env(&audio_opts->device->kobj,
+			KOBJ_CHANGE, envp);
+}
+
 static void afunc_free_inst(struct usb_function_instance *f)
 {
 	struct f_uac2_opts *opts;
 
 	opts = container_of(f, struct f_uac2_opts, func_inst);
+	device_destroy(opts->device->class, opts->device->devt);
+	cancel_work_sync(&opts->work);
 	kfree(opts);
 }
 
@@ -1082,6 +1126,9 @@ static struct usb_function_instance *afunc_alloc_inst(void)
 	opts->c_srate = UAC2_DEF_CSRATE;
 	opts->c_ssize = UAC2_DEF_CSSIZE;
 	opts->req_number = UAC2_DEF_REQ_NUM;
+	INIT_WORK(&opts->work, f_uac2_audio_status_change_work);
+	opts->device = create_function_device("f_uac2");
+
 	return &opts->func_inst;
 }
 
diff --git a/drivers/usb/gadget/function/u_uac2.h b/drivers/usb/gadget/function/u_uac2.h
index b5035711172d..3ccf2eb002f1 100644
--- a/drivers/usb/gadget/function/u_uac2.h
+++ b/drivers/usb/gadget/function/u_uac2.h
@@ -36,6 +36,11 @@ struct f_uac2_opts {
 
 	struct mutex			lock;
 	int				refcnt;
+	int				c_status;
+	int				p_status;
+	struct device			*device;
+	struct work_struct		work;
 };
 
+extern struct device *create_function_device(char *name);
 #endif
-- 
2.17.1