Commit 1c937381 authored by Victor Krawiec's avatar Victor Krawiec Committed by Greg Kroah-Hartman
Browse files

usb: gadget: f_midi: allow customizing the USB MIDI interface string through configfs 



When using f_midi from configfs the USB MIDI interface string is hardcoded
to 'MIDI function'.

This USB string descriptor is used by some third-party OS or software to
display the name of the MIDI device

Since we add an additional string option a new macro block was created to
factorize declarations

Signed-off-by: default avatarVictor Krawiec <victor.krawiec@arturia.com>
Reviewed-by: default avatarTakashi Iwai <tiwai@suse.de>
Link: https://patch.msgid.link/20251209164006.143219-1-victor.krawiec@arturia.com


Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 4dee13db

Documentation/ABI/testing/configfs-usb-gadget-midi

+9 −8
Original line number Diff line number Diff line
@@ -4,11 +4,12 @@ KernelVersion: 3.19 
Description:

		The attributes:



		==========	====================================

		================	====================================

		index			index value for the USB MIDI adapter

		id			ID string for the USB MIDI adapter

		buflen			MIDI buffer length

		qlen			USB read request queue length

		in_ports		number of MIDI input ports

		out_ports		number of MIDI output ports

		==========	====================================
 
		interface_string	USB AudioControl interface string

		================	====================================

Documentation/usb/gadget-testing.rst

+9 −8
Original line number Diff line number Diff line
@@ -368,14 +368,15 @@ Function-specific configfs interface 
The function name to use when creating the function directory is "midi".

The MIDI function provides these attributes in its function directory:



	=============== ====================================

	================ ====================================

	buflen		 MIDI buffer length

	id		 ID string for the USB MIDI adapter

	in_ports	 number of MIDI input ports

	index		 index value for the USB MIDI adapter

	out_ports	 number of MIDI output ports

	qlen		 USB read request queue length

	=============== ====================================

	interface_string USB AudioControl interface string

	================ ====================================



Testing the MIDI function

-------------------------

drivers/usb/gadget/function/f_midi.c

+59 −51
Original line number Diff line number Diff line
@@ -875,6 +875,7 @@ static int f_midi_bind(struct usb_configuration *c, struct usb_function *f) 
	struct usb_composite_dev *cdev = c->cdev;

	struct f_midi *midi = func_to_midi(f);

	struct usb_string *us;

	struct f_midi_opts *opts;

	int status, n, jack = 1, i = 0, endpoint_descriptor_index = 0;



	midi->gadget = cdev->gadget;
@@ -883,6 +884,10 @@ static int f_midi_bind(struct usb_configuration *c, struct usb_function *f) 
	if (status < 0)

		goto fail_register;



	opts = container_of(f->fi, struct f_midi_opts, func_inst);

	if (opts->interface_string)

		midi_string_defs[STRING_FUNC_IDX].s = opts->interface_string;



	/* maybe allocate device-global string ID */

	us = usb_gstrings_attach(c->cdev, midi_strings,

				 ARRAY_SIZE(midi_string_defs));
@@ -1178,59 +1183,60 @@ end: \ 
									\

CONFIGFS_ATTR(f_midi_opts_, name);



#define F_MIDI_OPT_STRING(name)						\

static ssize_t f_midi_opts_##name##_show(struct config_item *item, char *page) \

{									\

	struct f_midi_opts *opts = to_f_midi_opts(item);		\

	ssize_t result;							\

									\

	mutex_lock(&opts->lock);					\

	if (opts->name) {						\

		result = strscpy(page, opts->name, PAGE_SIZE);		\

	} else {							\

		page[0] = 0;						\

		result = 0;						\

	}								\

									\

	mutex_unlock(&opts->lock);					\

									\

	return result;							\

}									\

									\

static ssize_t f_midi_opts_##name##_store(struct config_item *item,	\

					 const char *page, size_t len)	\

{									\

	struct f_midi_opts *opts = to_f_midi_opts(item);		\

	int ret;							\

	char *c;							\

									\

	mutex_lock(&opts->lock);					\

	if (opts->refcnt > 1) {						\

		ret = -EBUSY;						\

		goto end;						\

	}								\

									\

	c = kstrndup(page, len, GFP_KERNEL);				\

	if (!c) {							\

		ret = -ENOMEM;						\

		goto end;						\

	}								\

	kfree(opts->name);						\

	opts->name = c;							\

	ret = len;							\

end:									\

	mutex_unlock(&opts->lock);					\

	return ret;							\

}									\

									\

CONFIGFS_ATTR(f_midi_opts_, name)



F_MIDI_OPT_SIGNED(index, true, SNDRV_CARDS);

F_MIDI_OPT(buflen, false, 0);

F_MIDI_OPT(qlen, false, 0);

F_MIDI_OPT(in_ports, true, MAX_PORTS);

F_MIDI_OPT(out_ports, true, MAX_PORTS);



static ssize_t f_midi_opts_id_show(struct config_item *item, char *page)

{

	struct f_midi_opts *opts = to_f_midi_opts(item);

	ssize_t result;



	mutex_lock(&opts->lock);

	if (opts->id) {

		result = strscpy(page, opts->id, PAGE_SIZE);

	} else {

		page[0] = 0;

		result = 0;

	}



	mutex_unlock(&opts->lock);



	return result;

}



static ssize_t f_midi_opts_id_store(struct config_item *item,

				    const char *page, size_t len)

{

	struct f_midi_opts *opts = to_f_midi_opts(item);

	int ret;

	char *c;



	mutex_lock(&opts->lock);

	if (opts->refcnt > 1) {

		ret = -EBUSY;

		goto end;

	}



	c = kstrndup(page, len, GFP_KERNEL);

	if (!c) {

		ret = -ENOMEM;

		goto end;

	}

	if (opts->id_allocated)

		kfree(opts->id);

	opts->id = c;

	opts->id_allocated = true;

	ret = len;

end:

	mutex_unlock(&opts->lock);

	return ret;

}



CONFIGFS_ATTR(f_midi_opts_, id);

F_MIDI_OPT_STRING(id);

F_MIDI_OPT_STRING(interface_string);



static struct configfs_attribute *midi_attrs[] = {

	&f_midi_opts_attr_index,
@@ -1239,6 +1245,7 @@ static struct configfs_attribute *midi_attrs[] = { 
	&f_midi_opts_attr_in_ports,

	&f_midi_opts_attr_out_ports,

	&f_midi_opts_attr_id,

	&f_midi_opts_attr_interface_string,

	NULL,

};
@@ -1262,8 +1269,8 @@ static void f_midi_free_inst(struct usb_function_instance *f) 
	mutex_unlock(&opts->lock);



	if (free) {

		if (opts->id_allocated)

		kfree(opts->id);

		kfree(opts->interface_string);

		kfree(opts);

	}

}
@@ -1279,7 +1286,8 @@ static struct usb_function_instance *f_midi_alloc_inst(void) 
	mutex_init(&opts->lock);

	opts->func_inst.free_func_inst = f_midi_free_inst;

	opts->index = SNDRV_DEFAULT_IDX1;

	opts->id = SNDRV_DEFAULT_STR1;

	opts->id = NULL;

	opts->interface_string = NULL;

	opts->buflen = 512;

	opts->qlen = 32;

	opts->in_ports = 1;

drivers/usb/gadget/function/u_midi.h

+1 −1
Original line number Diff line number Diff line
@@ -19,7 +19,7 @@ struct f_midi_opts { 
	struct usb_function_instance	func_inst;

	int				index;

	char				*id;

	bool				id_allocated;

	char				*interface_string;

	unsigned int			in_ports;

	unsigned int			out_ports;

	unsigned int			buflen;