From: Chris Wulff <crwulff@gmail.com>

The number of strings is now dependent on how many alt modes exist and
what their strings are set to. This allows the strings to be dynamically
consolidated where alt modes use the same strings, or separate when
different strings are configured in some alt modes.

Signed-off-by: Chris Wulff <crwulff@gmail.com>
---
 drivers/usb/gadget/function/f_uac1.c | 168 ++++++++++++++++++---------
 1 file changed, 110 insertions(+), 58 deletions(-)

diff --git a/drivers/usb/gadget/function/f_uac1.c b/drivers/usb/gadget/function/f_uac1.c
index e7bfc32387bf..3484aa237354 100644
--- a/drivers/usb/gadget/function/f_uac1.c
+++ b/drivers/usb/gadget/function/f_uac1.c
@@ -498,35 +498,6 @@ static struct usb_descriptor_header *f_audio_ss_desc[] = {
 	NULL,
 };
 
-enum {
-	STR_AC_IF,
-	STR_USB_OUT_IT,
-	STR_USB_OUT_IT_CH_NAMES,
-	STR_IO_OUT_OT,
-	STR_IO_IN_IT,
-	STR_IO_IN_IT_CH_NAMES,
-	STR_USB_IN_OT,
-	STR_FU_IN,
-	STR_FU_OUT,
-	STR_AS_OUT_IF_ALT0,
-	STR_AS_OUT_IF_ALT1,
-	STR_AS_IN_IF_ALT0,
-	STR_AS_IN_IF_ALT1,
-	NUM_STR_DESCRIPTORS,
-};
-
-static struct usb_string strings_uac1[NUM_STR_DESCRIPTORS + 1] = {};
-
-static struct usb_gadget_strings str_uac1 = {
-	.language = 0x0409,	/* en-us */
-	.strings = strings_uac1,
-};
-
-static struct usb_gadget_strings *uac1_strings[] = {
-	&str_uac1,
-	NULL,
-};
-
 /*
  * This function is an ALSA sound card following USB Audio Class Spec 1.0.
  */
@@ -1163,6 +1134,93 @@ f_audio_suspend(struct usb_function *f)
 
 /*-------------------------------------------------------------------------*/
 
+/*
+ * String handling
+ */
+
+#define MAX_STRINGS 256
+
+static int add_string(struct usb_string *strings, const char *s)
+{
+	int i;
+
+	if (!s || s[0] == '\0')
+		return 0;
+
+	for (i = 0; i < MAX_STRINGS; i++) {
+		if (!strings[i].s) {
+			strings[i].s = s;
+			return 0; /* IDs aren't allocated yet */
+		}
+
+		if (!strcmp(s, strings[i].s))
+			return strings[i].id;
+	}
+
+	return -1;
+}
+
+static void add_alt_strings(struct usb_string *strings, struct f_uac1_alt_opts *alt_opts, bool fu)
+{
+	add_string(strings, alt_opts->name);
+	add_string(strings, alt_opts->it_name);
+	add_string(strings, alt_opts->it_ch_name);
+	add_string(strings, alt_opts->ot_name);
+	if (fu)
+		add_string(strings, alt_opts->fu_vol_name);
+}
+
+static struct usb_string *attach_strings(struct usb_composite_dev *cdev,
+					 struct f_uac1_opts *audio_opts)
+{
+	struct usb_string	*strings = kzalloc(sizeof(struct usb_string) * MAX_STRINGS,
+						   GFP_KERNEL);
+	struct f_uac1_alt_opts	*alt_opts;
+	struct usb_string	*us;
+	int			strings_uac1_length;
+
+	struct usb_gadget_strings str_uac1 = {
+		.language = 0x0409,	/* en-us */
+		.strings = strings
+	};
+
+	struct usb_gadget_strings *uac1_strings[] = {
+		&str_uac1,
+		NULL,
+	};
+
+	if (!strings)
+		return ERR_PTR(-ENOMEM);
+
+	/* Add all the strings from all the alt mode options */
+	add_string(strings, audio_opts->function_name);
+	add_string(strings, audio_opts->c_alt_0_opts.name);
+	add_string(strings, audio_opts->p_alt_0_opts.name);
+	add_alt_strings(strings, &audio_opts->c_alt_1_opts, FUOUT_EN(audio_opts));
+	add_alt_strings(strings, &audio_opts->p_alt_1_opts, FUIN_EN(audio_opts));
+	list_for_each_entry(alt_opts, &audio_opts->c_alt_opts, list) {
+		add_alt_strings(strings, alt_opts, FUOUT_EN(audio_opts));
+	}
+	list_for_each_entry(alt_opts, &audio_opts->p_alt_opts, list) {
+		add_alt_strings(strings, alt_opts, FUIN_EN(audio_opts));
+	}
+
+	for (strings_uac1_length = 0; strings[strings_uac1_length].s; strings_uac1_length++)
+		;
+
+	/* Attach strings to the composite device and get string IDs assigned */
+	us = usb_gstrings_attach(cdev, uac1_strings, strings_uac1_length);
+
+	/* Strings are now copied to the composite device and we use the
+	 * copy in "us" going forward, that has all the string IDs.
+	 */
+	kfree(strings);
+
+	return us;
+}
+
+/*-------------------------------------------------------------------------*/
+
 static int set_ep_max_packet_size_bint(struct device *dev, const struct f_uac1_alt_opts *alt_opts,
 					struct usb_endpoint_descriptor *ep_desc,
 					enum usb_device_speed speed, bool is_playback)
@@ -1526,23 +1584,11 @@ static int f_audio_bind(struct usb_configuration *c, struct usb_function *f)
 	if (status)
 		return status;
 
-	strings_uac1[STR_AC_IF].s = audio_opts->function_name;
-
-	strings_uac1[STR_USB_OUT_IT].s = audio_opts->c_it_name;
-	strings_uac1[STR_USB_OUT_IT_CH_NAMES].s = audio_opts->c_it_ch_name;
-	strings_uac1[STR_IO_OUT_OT].s = audio_opts->c_ot_name;
-	strings_uac1[STR_FU_OUT].s = audio_opts->c_fu_vol_name;
-	strings_uac1[STR_AS_OUT_IF_ALT0].s = "Playback Inactive";
-	strings_uac1[STR_AS_OUT_IF_ALT1].s = "Playback Active";
-
-	strings_uac1[STR_IO_IN_IT].s = audio_opts->p_it_name;
-	strings_uac1[STR_IO_IN_IT_CH_NAMES].s = audio_opts->p_it_ch_name;
-	strings_uac1[STR_USB_IN_OT].s = audio_opts->p_ot_name;
-	strings_uac1[STR_FU_IN].s = audio_opts->p_fu_vol_name;
-	strings_uac1[STR_AS_IN_IF_ALT0].s = "Capture Inactive";
-	strings_uac1[STR_AS_IN_IF_ALT1].s = "Capture Active";
+	/* Past this point, all settings that apply to an alt mode should
+	 * be used from their alt mode opts.
+	 */
 
-	us = usb_gstrings_attach(cdev, uac1_strings, ARRAY_SIZE(strings_uac1));
+	us = attach_strings(cdev, audio_opts);
 	if (IS_ERR(us))
 		return PTR_ERR(us);
 
@@ -1565,31 +1611,37 @@ static int f_audio_bind(struct usb_configuration *c, struct usb_function *f)
 		}
 	}
 
-	ac_interface_desc.iInterface = us[STR_AC_IF].id;
-	usb_out_it_desc.iTerminal = us[STR_USB_OUT_IT].id;
-	usb_out_it_desc.iChannelNames = us[STR_USB_OUT_IT_CH_NAMES].id;
-	io_out_ot_desc.iTerminal = us[STR_IO_OUT_OT].id;
-	as_out_interface_alt_0_desc.iInterface = us[STR_AS_OUT_IF_ALT0].id;
-	as_out_interface_alt_1_desc.iInterface = us[STR_AS_OUT_IF_ALT1].id;
-	io_in_it_desc.iTerminal = us[STR_IO_IN_IT].id;
-	io_in_it_desc.iChannelNames = us[STR_IO_IN_IT_CH_NAMES].id;
-	usb_in_ot_desc.iTerminal = us[STR_USB_IN_OT].id;
-	as_in_interface_alt_0_desc.iInterface = us[STR_AS_IN_IF_ALT0].id;
-	as_in_interface_alt_1_desc.iInterface = us[STR_AS_IN_IF_ALT1].id;
+	ac_interface_desc.iInterface = add_string(us, audio_opts->function_name);
+	usb_out_it_desc.iTerminal = add_string(us, audio_opts->c_alt_1_opts.it_name);
+	usb_out_it_desc.iChannelNames = add_string(us, audio_opts->c_alt_1_opts.it_ch_name);
+	io_out_ot_desc.iTerminal = add_string(us, audio_opts->c_alt_1_opts.ot_name);
+	as_out_interface_alt_0_desc.iInterface = add_string(us, audio_opts->c_alt_0_opts.name);
+	as_out_interface_alt_1_desc.iInterface = add_string(us, audio_opts->c_alt_1_opts.name);
+	io_in_it_desc.iTerminal = add_string(us, audio_opts->p_alt_1_opts.it_name);
+	io_in_it_desc.iChannelNames = add_string(us, audio_opts->p_alt_1_opts.it_ch_name);
+	usb_in_ot_desc.iTerminal = add_string(us, audio_opts->p_alt_1_opts.ot_name);
+	as_in_interface_alt_0_desc.iInterface = add_string(us, audio_opts->p_alt_0_opts.name);
+	as_in_interface_alt_1_desc.iInterface = add_string(us, audio_opts->p_alt_1_opts.name);
 
 	if (FUOUT_EN(audio_opts)) {
 		u8 *i_feature;
 
 		i_feature = (u8 *)out_feature_unit_desc +
 					out_feature_unit_desc->bLength - 1;
-		*i_feature = us[STR_FU_OUT].id;
+		*i_feature = add_string(us, audio_opts->c_alt_1_opts.fu_vol_name);
 	}
 	if (FUIN_EN(audio_opts)) {
 		u8 *i_feature;
 
 		i_feature = (u8 *)in_feature_unit_desc +
 					in_feature_unit_desc->bLength - 1;
-		*i_feature = us[STR_FU_IN].id;
+		*i_feature = add_string(us, audio_opts->p_alt_1_opts.fu_vol_name);
+	}
+
+	us = attach_strings(cdev, audio_opts);
+	if (IS_ERR(us)) {
+		status = PTR_ERR(us);
+		goto fail;
 	}
 
 	/* Set channel numbers */
-- 
2.43.0