usb: gadget: f_uac2: allow changing interface name via configfs

This adds "function_name" configfs entry to change string value
of the iInterface field. This field will be shown in Windows' audio
settings panel, so being able to change it is useful. It will default
to "Source/Sink" just as before.

Signed-off-by: Yunhao Tian <t123yh.xyz@gmail.com>
Link: https://lore.kernel.org/r/20220122112446.1415547-2-t123yh.xyz@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/Documentation/ABI/testing/configfs-usb-gadget-uac2 b/Documentation/ABI/testing/configfs-usb-gadget-uac2
index 9d2f59a..4c6bf63 100644 (file)
--- a/Documentation/ABI/testing/configfs-usb-gadget-uac2
+++ b/Documentation/ABI/testing/configfs-usb-gadget-uac2
@@ -32,4 +32,5 @@ Description:
                                        (in 1/256 dB)
                req_number              the number of pre-allocated requests
                                        for both capture and playback
+               function_name           name of the interface
                =====================   =======================================

diff --git a/Documentation/usb/gadget-testing.rst b/Documentation/usb/gadget-testing.rst
index 1792bd8..6e8fdfa 100644 (file)
--- a/Documentation/usb/gadget-testing.rst
+++ b/Documentation/usb/gadget-testing.rst
@@ -934,6 +934,7 @@ The uac1 function provides these attributes in its function directory:
        p_volume_res     playback volume control resolution (in 1/256 dB)
        req_number       the number of pre-allocated requests for both capture
                         and playback
+       function_name    name of the interface
        ================ ====================================================
 
 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 3e63394..d874e0d 100644 (file)
--- a/drivers/usb/gadget/function/f_uac2.c
+++ b/drivers/usb/gadget/function/f_uac2.c
@@ -107,7 +107,7 @@ enum {
 };
 
 static struct usb_string strings_fn[] = {
-       [STR_ASSOC].s = "Source/Sink",
+       /* [STR_ASSOC].s = DYNAMIC, */
        [STR_IF_CTRL].s = "Topology Control",
        [STR_CLKSRC_IN].s = "Input Clock",
        [STR_CLKSRC_OUT].s = "Output Clock",
@@ -984,6 +984,8 @@ afunc_bind(struct usb_configuration *cfg, struct usb_function *fn)
        if (ret)
                return ret;
 
+       strings_fn[STR_ASSOC].s = uac2_opts->function_name;
+
        us = usb_gstrings_attach(cdev, fn_strings, ARRAY_SIZE(strings_fn));
        if (IS_ERR(us))
                return PTR_ERR(us);
@@ -1963,6 +1965,42 @@ end:                                                                     \
                                                                        \
 CONFIGFS_ATTR(f_uac2_opts_, name)
 
+#define UAC2_ATTRIBUTE_STRING(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 = snprintf(page, sizeof(opts->name), "%s", opts->name);  \
+       mutex_unlock(&opts->lock);                                      \
+                                                                       \
+       return result;                                                  \
+}                                                                      \
+                                                                       \
+static ssize_t f_uac2_opts_##name##_store(struct config_item *item,    \
+                                         const char *page, size_t len) \
+{                                                                      \
+       struct f_uac2_opts *opts = to_f_uac2_opts(item);                \
+       int ret = 0;                                                    \
+                                                                       \
+       mutex_lock(&opts->lock);                                        \
+       if (opts->refcnt) {                                             \
+               ret = -EBUSY;                                           \
+               goto end;                                               \
+       }                                                               \
+                                                                       \
+       ret = snprintf(opts->name, min(sizeof(opts->name), len),        \
+                       "%s", page);                                    \
+                                                                       \
+end:                                                                   \
+       mutex_unlock(&opts->lock);                                      \
+       return ret;                                                     \
+}                                                                      \
+                                                                       \
+CONFIGFS_ATTR(f_uac2_opts_, name)
+
 UAC2_ATTRIBUTE(u32, p_chmask);
 UAC2_RATE_ATTRIBUTE(p_srate);
 UAC2_ATTRIBUTE(u32, p_ssize);
@@ -1984,6 +2022,7 @@ UAC2_ATTRIBUTE(s16, c_volume_min);
 UAC2_ATTRIBUTE(s16, c_volume_max);
 UAC2_ATTRIBUTE(s16, c_volume_res);
 UAC2_ATTRIBUTE(u32, fb_max);
+UAC2_ATTRIBUTE_STRING(function_name);
 
 static struct configfs_attribute *f_uac2_attrs[] = {
        &f_uac2_opts_attr_p_chmask,
@@ -2008,6 +2047,8 @@ static struct configfs_attribute *f_uac2_attrs[] = {
        &f_uac2_opts_attr_c_volume_max,
        &f_uac2_opts_attr_c_volume_res,
 
+       &f_uac2_opts_attr_function_name,
+
        NULL,
 };
 
@@ -2061,6 +2102,9 @@ static struct usb_function_instance *afunc_alloc_inst(void)
 
        opts->req_number = UAC2_DEF_REQ_NUM;
        opts->fb_max = FBACK_FAST_MAX;
+
+       snprintf(opts->function_name, sizeof(opts->function_name), "Source/Sink");
+
        return &opts->func_inst;
 }
 

diff --git a/drivers/usb/gadget/function/u_uac2.h b/drivers/usb/gadget/function/u_uac2.h
index 6bfcf6d..ed96c7c 100644 (file)
--- a/drivers/usb/gadget/function/u_uac2.h
+++ b/drivers/usb/gadget/function/u_uac2.h
@@ -59,6 +59,8 @@ struct f_uac2_opts {
        int                             fb_max;
        bool                    bound;
 
+       char                    function_name[32];
+
        struct mutex                    lock;
        int                             refcnt;
 };