usb: gadget: f_uac2: add configfs support

Add support for using f_uac2 function as a component of a gadget
composed with configfs.

Tested-by: Sebastian Reimers <sebastian.reimers@googlemail.com>
Signed-off-by: Andrzej Pietrasiewicz <andrzej.p@samsung.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>

2 files changed, 108 insertions, 0 deletions

diff --git a/drivers/usb/gadget/function/f_uac2.c b/drivers/usb/gadget/function/f_uac2.c
index 1b9671effa12..0d65e7c08a93 100644
--- a/drivers/usb/gadget/function/f_uac2.c
+++ b/drivers/usb/gadget/function/f_uac2.c
@@ -1330,6 +1330,93 @@ afunc_setup(struct usb_function *fn, const struct usb_ctrlrequest *cr)
         return value;
 }
 
+static inline struct f_uac2_opts *to_f_uac2_opts(struct config_item *item)
+{
+        return container_of(to_config_group(item), struct f_uac2_opts,
+                            func_inst.group);
+}
+
+CONFIGFS_ATTR_STRUCT(f_uac2_opts);
+CONFIGFS_ATTR_OPS(f_uac2_opts);
+
+static void f_uac2_attr_release(struct config_item *item)
+{
+        struct f_uac2_opts *opts = to_f_uac2_opts(item);
+
+        usb_put_function_instance(&opts->func_inst);
+}
+
+static struct configfs_item_operations f_uac2_item_ops = {
+        .release        = f_uac2_attr_release,
+        .show_attribute = f_uac2_opts_attr_show,
+        .store_attribute = f_uac2_opts_attr_store,
+};
+
+#define UAC2_ATTRIBUTE(name)                                            \
+static ssize_t f_uac2_opts_##name##_show(struct f_uac2_opts *opts,      \
+                                         char *page)                    \
+{                                                                       \
+        int result;                                                     \
+                                                                        \
+        mutex_lock(&opts->lock);                                        \
+        result = sprintf(page, "%u\n", opts->name);                     \
+        mutex_unlock(&opts->lock);                                      \
+                                                                        \
+        return result;                                                  \
+}                                                                       \
+                                                                        \
+static ssize_t f_uac2_opts_##name##_store(struct f_uac2_opts *opts,     \
+                                          const char *page, size_t len) \
+{                                                                       \
+        int ret;                                                        \
+        u32 num;                                                        \
+                                                                        \
+        mutex_lock(&opts->lock);                                        \
+        if (opts->refcnt) {                                             \
+                ret = -EBUSY;                                           \
+                goto end;                                               \
+        }                                                               \
+                                                                        \
+        ret = kstrtou32(page, 0, &num);                                 \
+        if (ret)                                                        \
+                goto end;                                               \
+                                                                        \
+        opts->name = num;                                               \
+        ret = len;                                                      \
+                                                                        \
+end:                                                                    \
+        mutex_unlock(&opts->lock);                                      \
+        return ret;                                                     \
+}                                                                       \
+                                                                        \
+static struct f_uac2_opts_attribute f_uac2_opts_##name =                \
+        __CONFIGFS_ATTR(name, S_IRUGO | S_IWUSR,                        \
+                        f_uac2_opts_##name##_show,                      \
+                        f_uac2_opts_##name##_store)
+
+UAC2_ATTRIBUTE(p_chmask);
+UAC2_ATTRIBUTE(p_srate);
+UAC2_ATTRIBUTE(p_ssize);
+UAC2_ATTRIBUTE(c_chmask);
+UAC2_ATTRIBUTE(c_srate);
+UAC2_ATTRIBUTE(c_ssize);
+
+static struct configfs_attribute *f_uac2_attrs[] = {
+        &f_uac2_opts_p_chmask.attr,
+        &f_uac2_opts_p_srate.attr,
+        &f_uac2_opts_p_ssize.attr,
+        &f_uac2_opts_c_chmask.attr,
+        &f_uac2_opts_c_srate.attr,
+        &f_uac2_opts_c_ssize.attr,
+        NULL,
+};
+
+static struct config_item_type f_uac2_func_type = {
+        .ct_item_ops    = &f_uac2_item_ops,
+        .ct_attrs       = f_uac2_attrs,
+        .ct_owner       = THIS_MODULE,
+};
+
 static void afunc_free_inst(struct usb_function_instance *f)
 {
         struct f_uac2_opts *opts;
@@ -1346,17 +1433,32 @@ static struct usb_function_instance *afunc_alloc_inst(void)
         if (!opts)
                 return ERR_PTR(-ENOMEM);
 
+        mutex_init(&opts->lock);
         opts->func_inst.free_func_inst = afunc_free_inst;
 
+        config_group_init_type_name(&opts->func_inst.group, "",
+                                    &f_uac2_func_type);
+
+        opts->p_chmask = UAC2_DEF_PCHMASK;
+        opts->p_srate = UAC2_DEF_PSRATE;
+        opts->p_ssize = UAC2_DEF_PSSIZE;
+        opts->c_chmask = UAC2_DEF_CCHMASK;
+        opts->c_srate = UAC2_DEF_CSRATE;
+        opts->c_ssize = UAC2_DEF_CSSIZE;
         return &opts->func_inst;
 }
 
 static void afunc_free(struct usb_function *f)
 {
         struct audio_dev *agdev;
+        struct f_uac2_opts *opts;
 
         agdev = func_to_agdev(f);
+        opts = container_of(f->fi, struct f_uac2_opts, func_inst);
         kfree(agdev);
+        mutex_lock(&opts->lock);
+        --opts->refcnt;
+        mutex_unlock(&opts->lock);
 }
 
 static void afunc_unbind(struct usb_configuration *c, struct usb_function *f)
@@ -1389,6 +1491,9 @@ struct usb_function *afunc_alloc(struct usb_function_instance *fi)
                 return ERR_PTR(-ENOMEM);
 
         opts = container_of(fi, struct f_uac2_opts, func_inst);
+        mutex_lock(&opts->lock);
+        ++opts->refcnt;
+        mutex_unlock(&opts->lock);
 
         agdev->func.name = "uac2_func";
         agdev->func.bind = afunc_bind;
diff --git a/drivers/usb/gadget/function/u_uac2.h b/drivers/usb/gadget/function/u_uac2.h
index ed7f7361a53e..78dd37279bd4 100644
--- a/drivers/usb/gadget/function/u_uac2.h
+++ b/drivers/usb/gadget/function/u_uac2.h
@@ -34,6 +34,9 @@ struct f_uac2_opts {
         int                             c_srate;
         int                             c_ssize;
         bool                            bound;
+
+        struct mutex                    lock;
+        int                             refcnt;
 };
 
 #endif