usb: gadget: f_uac1: Support multiple sampling rates

A list of sampling rates can be specified via configfs. All enabled
sampling rates are sent to the USB host on request. When the host
selects a sampling rate the internal active rate is updated.

Config strings with single value stay compatible with the previous version.

Multiple samplerates passed as configuration arrays to g_audio module
when built for f_uac1.
Signed-off-by: Julian Scheel <julian@jusst.de>
Signed-off-by: Pavel Hofman <pavel.hofman@ivitera.com>
Link: https://lore.kernel.org/r/20220121155308.48794-7-pavel.hofman@ivitera.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Documentation/ABI/testing/configfs-usb-gadget-uac1

@@ -6,7 +6,7 @@ Description:
 
 		=====================	=======================================
 		c_chmask		capture channel mask
-		c_srate			capture sampling rate
+		c_srate			list of capture sampling rates (comma-separated)
 		c_ssize			capture sample size (bytes)
 		c_mute_present		capture mute control enable
 		c_volume_present	capture volume control enable
@@ -17,7 +17,7 @@ Description:
 		c_volume_res		capture volume control resolution
 					(in 1/256 dB)
 		p_chmask		playback channel mask
-		p_srate			playback sampling rate
+		p_srate			list of playback sampling rates (comma-separated)
 		p_ssize			playback sample size (bytes)
 		p_mute_present		playback mute control enable
 		p_volume_present	playback volume control enable

Documentation/usb/gadget-testing.rst

@@ -916,7 +916,7 @@ The uac1 function provides these attributes in its function directory:
 
 	================ ====================================================
 	c_chmask         capture channel mask
-	c_srate          capture sampling rate
+	c_srate          list of capture sampling rates (comma-separated)
 	c_ssize          capture sample size (bytes)
 	c_mute_present   capture mute control enable
 	c_volume_present capture volume control enable
@@ -924,7 +924,7 @@ The uac1 function provides these attributes in its function directory:
 	c_volume_max     capture volume control max value (in 1/256 dB)
 	c_volume_res     capture volume control resolution (in 1/256 dB)
 	p_chmask         playback channel mask
-	p_srate          playback sampling rate
+	p_srate          list of playback sampling rates (comma-separated)
 	p_ssize          playback sample size (bytes)
 	p_mute_present   playback mute control enable
 	p_volume_present playback volume control enable

drivers/usb/gadget/function/u_uac1.h

@@ -9,6 +9,7 @@
 #define __U_UAC1_H
 
 #include <linux/usb/composite.h>
+#include "uac_common.h"
 
 #define UAC1_OUT_EP_MAX_PACKET_SIZE	200
 #define UAC1_DEF_CCHMASK	0x3
@@ -30,10 +31,10 @@
 struct f_uac1_opts {
 	struct usb_function_instance	func_inst;
 	int				c_chmask;
-	int				c_srate;
+	int				c_srates[UAC_MAX_RATES];
 	int				c_ssize;
 	int				p_chmask;
-	int				p_srate;
+	int				p_srates[UAC_MAX_RATES];
 	int				p_ssize;
 
 	bool			p_mute_present;

drivers/usb/gadget/legacy/audio.c

@@ -61,9 +61,10 @@ module_param(p_chmask, uint, 0444);
 MODULE_PARM_DESC(p_chmask, "Playback Channel Mask");
 
 /* Playback Default 48 KHz */
-static int p_srate = UAC1_DEF_PSRATE;
-module_param(p_srate, uint, 0444);
-MODULE_PARM_DESC(p_srate, "Playback Sampling Rate");
+static int p_srates[UAC_MAX_RATES] = {UAC1_DEF_PSRATE};
+static int p_srates_cnt = 1;
+module_param_array_named(p_srate, p_srates, uint, &p_srates_cnt, 0444);
+MODULE_PARM_DESC(p_srate, "Playback Sampling Rates (array)");
 
 /* Playback Default 16bits/sample */
 static int p_ssize = UAC1_DEF_PSSIZE;
@@ -76,9 +77,10 @@ module_param(c_chmask, uint, 0444);
 MODULE_PARM_DESC(c_chmask, "Capture Channel Mask");
 
 /* Capture Default 48 KHz */
-static int c_srate = UAC1_DEF_CSRATE;
-module_param(c_srate, uint, 0444);
-MODULE_PARM_DESC(c_srate, "Capture Sampling Rate");
+static int c_srates[UAC_MAX_RATES] = {UAC1_DEF_CSRATE};
+static int c_srates_cnt = 1;
+module_param_array_named(c_srate, c_srates, uint, &c_srates_cnt, 0444);
+MODULE_PARM_DESC(c_srate, "Capture Sampling Rates (array)");
 
 /* Capture Default 16bits/sample */
 static int c_ssize = UAC1_DEF_CSSIZE;
@@ -243,6 +245,7 @@ static int audio_bind(struct usb_composite_dev *cdev)
 #else
 #ifndef CONFIG_GADGET_UAC1_LEGACY
 	struct f_uac1_opts	*uac1_opts;
+	int i;
 #else
 	struct f_uac1_legacy_opts	*uac1_opts;
 #endif
@@ -282,10 +285,16 @@ static int audio_bind(struct usb_composite_dev *cdev)
 #ifndef CONFIG_GADGET_UAC1_LEGACY
 	uac1_opts = container_of(fi_uac1, struct f_uac1_opts, func_inst);
 	uac1_opts->p_chmask = p_chmask;
-	uac1_opts->p_srate = p_srate;
+
+	for (i = 0; i < p_srates_cnt; ++i)
+		uac1_opts->p_srates[i] = p_srates[i];
+
 	uac1_opts->p_ssize = p_ssize;
 	uac1_opts->c_chmask = c_chmask;
-	uac1_opts->c_srate = c_srate;
+
+	for (i = 0; i < c_srates_cnt; ++i)
+		uac1_opts->c_srates[i] = c_srates[i];
+
 	uac1_opts->c_ssize = c_ssize;
 	uac1_opts->req_number = UAC1_DEF_REQ_NUM;
 #else /* CONFIG_GADGET_UAC1_LEGACY */