Currently string descriptors for the UVC function are largely hard
coded. It's not practically possible to support string descriptors
that describe Extension Units that way, so add a mechanism to the
configfs tree that allows the definition of arbitrary string
descriptors.
Signed-off-by: Daniel Scally <dan.scally@xxxxxxxxxxxxxxxx>
---
Changes in v2:
- New patch
.../ABI/testing/configfs-usb-gadget-uvc | 20 ++
drivers/usb/gadget/function/f_uvc.c | 1 +
drivers/usb/gadget/function/u_uvc.h | 7 +
drivers/usb/gadget/function/uvc_configfs.c | 302 ++++++++++++++++++
drivers/usb/gadget/function/uvc_configfs.h | 30 ++
5 files changed, 360 insertions(+)
diff --git a/Documentation/ABI/testing/configfs-usb-gadget-uvc b/Documentation/ABI/testing/configfs-usb-gadget-uvc
index 045c57e7e245..5faa049ed759 100644
--- a/Documentation/ABI/testing/configfs-usb-gadget-uvc
+++ b/Documentation/ABI/testing/configfs-usb-gadget-uvc
@@ -10,6 +10,26 @@ Description: UVC function directory
function_name string [32]
=================== =============================
+What: /config/usb-gadget/gadget/functions/uvc.name/strings
+Date: Nov 2022
+KernelVersion: 6.1
+Description: String descriptors
+
+What: /config/usb-gadget/gadget/functions/uvc.name/strings/langid
+Date: Nov 2022
+KernelVersion: 6.1
+Description: String descriptors for langid (e.g. 0x409)
+
+What: /config/usb-gadget/gadget/functions/uvc.name/strings/langid/name
+Date: Nov 2022
+KernelVersion: 6.1
+Description: String descriptor
+
+ =================== =============================
+ id id of the string descriptor
+ s 126 character string
+ =================== =============================
+
What: /config/usb-gadget/gadget/functions/uvc.name/control
Date: Dec 2014
KernelVersion: 4.0
diff --git a/drivers/usb/gadget/function/f_uvc.c b/drivers/usb/gadget/function/f_uvc.c
index e0a308f1355c..1b8871a24be8 100644
--- a/drivers/usb/gadget/function/f_uvc.c
+++ b/drivers/usb/gadget/function/f_uvc.c
@@ -912,6 +912,7 @@ static struct usb_function_instance *uvc_alloc_inst(void)
(const struct uvc_descriptor_header * const *)ctl_cls;
INIT_LIST_HEAD(&opts->extension_units);
+ INIT_LIST_HEAD(&opts->languages);
opts->streaming_interval = 1;
opts->streaming_maxpacket = 1024;
diff --git a/drivers/usb/gadget/function/u_uvc.h b/drivers/usb/gadget/function/u_uvc.h
index 5119cfe5ee4e..c1c9ea5931d3 100644
--- a/drivers/usb/gadget/function/u_uvc.h
+++ b/drivers/usb/gadget/function/u_uvc.h
@@ -81,6 +81,13 @@ struct f_uvc_opts {
struct uvc_descriptor_header **uvc_hs_streaming_cls;
struct uvc_descriptor_header **uvc_ss_streaming_cls;
+ /*
+ * A list of languages, associated with which may be string descriptors
+ * for various parts of the gadget, including the IAD and XUs.
+ */
+ struct list_head languages;
+ unsigned int nlangs;
+
/*
* Read/write access to configfs attributes is handled by configfs.
*
diff --git a/drivers/usb/gadget/function/uvc_configfs.c b/drivers/usb/gadget/function/uvc_configfs.c
index 0a69eb6cf221..da2f70036993 100644
--- a/drivers/usb/gadget/function/uvc_configfs.c
+++ b/drivers/usb/gadget/function/uvc_configfs.c
@@ -13,6 +13,8 @@
#include "uvc_configfs.h"
#include <linux/sort.h>
+#include <linux/usb/gadget.h>
+
/* -----------------------------------------------------------------------------
* Global Utility Structures and Macros
@@ -2824,6 +2826,305 @@ static const struct uvcg_config_group_type uvcg_streaming_grp_type = {
},
};
+/* -----------------------------------------------------------------------------
+ * strings/<langid>
+ */
+
+static ssize_t uvcg_string_id_show(struct config_item *item, char *page)
+{
+ struct config_group *group = to_config_group(item->ci_parent);
+ struct mutex *su_mutex = &group->cg_subsys->su_mutex;
+ struct uvcg_string *string = to_uvcg_string(item);
+ struct config_item *opts_item;
+ struct f_uvc_opts *opts;
+ int ret;
+
+ mutex_lock(su_mutex);
+
+ opts_item = item->ci_parent->ci_parent->ci_parent;
+ opts = to_f_uvc_opts(opts_item);
+
+ mutex_lock(&opts->lock);
+ ret = sprintf(page, "%u\n", string->usb_string.id);
+ mutex_unlock(&opts->lock);
+
+ mutex_unlock(su_mutex);
+
+ return ret;
+}
+UVC_ATTR_RO(uvcg_string_, id, id);
+
+static ssize_t uvcg_string_s_show(struct config_item *item, char *page)
+{
+ struct config_group *group = to_config_group(item->ci_parent);
+ struct mutex *su_mutex = &group->cg_subsys->su_mutex;
+ struct uvcg_string *string = to_uvcg_string(item);
+ struct config_item *opts_item;
+ struct f_uvc_opts *opts;
+ int ret;
+
+ mutex_lock(su_mutex);
+
+ opts_item = item->ci_parent->ci_parent->ci_parent;
+ opts = to_f_uvc_opts(opts_item);
+
+ mutex_lock(&opts->lock);
+ ret = snprintf(page, sizeof(string->string), "%s\n", string->string);
+ mutex_unlock(&opts->lock);
+
+ mutex_unlock(su_mutex);
+
+ return ret;
+}
+
+static ssize_t uvcg_string_s_store(struct config_item *item, const char *page,
+ size_t len)
+{
+ struct config_group *group = to_config_group(item->ci_parent);
+ struct mutex *su_mutex = &group->cg_subsys->su_mutex;
+ struct uvcg_string *string = to_uvcg_string(item);
+ int size = min(sizeof(string->string), len + 1);
+ struct config_item *opts_item;
+ struct f_uvc_opts *opts;
+ int ret;
+
+ if (len > USB_MAX_STRING_LEN)
+ return -EINVAL;
+
+ mutex_lock(su_mutex);
+
+ opts_item = item->ci_parent->ci_parent->ci_parent;
+ opts = to_f_uvc_opts(opts_item);
+
+ mutex_lock(&opts->lock);
+ ret = strscpy(string->string, page, size);
+ mutex_unlock(&opts->lock);
+
+ mutex_unlock(su_mutex);
+
+ return len;
+}
+UVC_ATTR(uvcg_string_, s, s);
+
+static struct configfs_attribute *uvcg_string_attrs[] = {
+ &uvcg_string_attr_id,
+ &uvcg_string_attr_s,
+ NULL,
+};
+
+static void uvcg_string_release(struct config_item *item)
+{
+ struct uvcg_string *string = to_uvcg_string(item);
+
+ kfree(string);
+}
+
+static struct configfs_item_operations uvcg_string_item_ops = {
+ .release = uvcg_string_release,
+};
+
+static const struct config_item_type uvcg_string_type = {
+ .ct_item_ops = &uvcg_string_item_ops,
+ .ct_attrs = uvcg_string_attrs,
+ .ct_owner = THIS_MODULE,
+};
+
+static struct config_item *uvcg_string_make(struct config_group *group,
+ const char *name)
+{
+ struct uvcg_language *language;
+ struct config_item *opts_item;
+ struct uvcg_string *string;
+ struct f_uvc_opts *opts;
+
+ language = to_uvcg_language(group);
+
+ string = kzalloc(sizeof(*string), GFP_KERNEL);
+ if (!string)
+ return ERR_PTR(-ENOMEM);
+
+ opts_item = group->cg_item.ci_parent->ci_parent;
+ opts = to_f_uvc_opts(opts_item);
+
+ mutex_lock(&opts->lock);
+
+ string->usb_string.id = language->nstrings++;
+ string->usb_string.s = string->string;
+ list_add_tail(&string->list, &language->strings);
+
+ config_item_init_type_name(&string->item, name, &uvcg_string_type);
+
+ mutex_unlock(&opts->lock);
+
+ return &string->item;
+}
+
+static void uvcg_string_drop(struct config_group *group, struct config_item *item)
+{
+ struct uvcg_language *language;
+ struct config_item *opts_item;
+ struct uvcg_string *string;
+ struct f_uvc_opts *opts;
+ unsigned int i = 1;
+
+ language = to_uvcg_language(group);
+ string = to_uvcg_string(item);
+
+ opts_item = group->cg_item.ci_parent->ci_parent;
+ opts = to_f_uvc_opts(opts_item);
+
+ mutex_lock(&opts->lock);
+
+ list_del(&string->list);
+ language->nstrings--;
+
+ /* Reset the ids for the language's strings to guarantee a continuous set */
+ list_for_each_entry(string, &language->strings, list)
+ string->usb_string.id = i++;
+
+ mutex_unlock(&opts->lock);
+}
+
+/* -----------------------------------------------------------------------------
+ * strings/
+ */
+
+static struct configfs_group_operations uvcg_language_group_ops = {
+ .make_item = uvcg_string_make,
+ .drop_item = uvcg_string_drop,
+};
+
+static void uvcg_language_release(struct config_item *item)
+{
+ struct uvcg_language *language = to_uvcg_language(to_config_group(item));
+
+ kfree(language);
+}
+
+static struct configfs_item_operations uvcg_language_item_ops = {
+ .release = uvcg_language_release,
+};
+
+/*
+ * The strings attribute is really a helper for users - having defined some string
+ * descriptors for this language, actually checking what's set when they're all
+ * in separate directories would be a bit...suboptimal. This read-only attribute
+ * gives a summary at language-level.
+ */
+static ssize_t uvcg_language_strings_show(struct config_item *item, char *page)
+{
+ struct config_group *group = to_config_group(item);
+ struct uvcg_language *language = to_uvcg_language(group);
+ struct mutex *su_mutex = &group->cg_subsys->su_mutex;
+ struct config_item *opts_item;
+ struct uvcg_string *string;
+ struct f_uvc_opts *opts;
+ char *pg = page;
+ int ret = 0;
+
+ mutex_lock(su_mutex);
+
+ opts_item = item->ci_parent->ci_parent;
+ opts = to_f_uvc_opts(opts_item);
+
+ mutex_lock(&opts->lock);
+
+ list_for_each_entry(string, &language->strings, list) {
+ ret += sprintf(pg, "%s: %s [%u]\n", string->item.ci_name,
+ string->usb_string.s, string->usb_string.id);
+ pg = page + ret;
+ }
+
+ mutex_unlock(&opts->lock);
+
+ mutex_unlock(su_mutex);
+
+ return ret;
+}
+UVC_ATTR_RO(uvcg_language_, strings, strings);
+
+static struct configfs_attribute *uvcg_language_attrs[] = {
+ &uvcg_language_attr_strings,
+ NULL
+};
+
+static const struct config_item_type uvcg_language_type = {
+ .ct_item_ops = &uvcg_language_item_ops,
+ .ct_group_ops = &uvcg_language_group_ops,
+ .ct_attrs = uvcg_language_attrs,
+ .ct_owner = THIS_MODULE,
+};
+
+static struct config_group *uvcg_language_make(struct config_group *group,
+ const char *name)
+{
+ struct uvcg_language *language;
+ struct config_item *opts_item;
+ struct f_uvc_opts *opts;
+ int ret;
+ u16 num;
+
+ ret = kstrtou16(name, 0, &num);
+ if (ret)
+ return ERR_PTR(ret);
+
+ if (!usb_validate_langid(num))
+ return ERR_PTR(-EINVAL);
+
+ language = kzalloc(sizeof(*language), GFP_KERNEL);
+ if (!language)
+ return ERR_PTR(-ENOMEM);
+
+ opts_item = group->cg_item.ci_parent;
+ opts = to_f_uvc_opts(opts_item);
+
+ mutex_lock(&opts->lock);
+
+ language->stringtab.language = num;
+ list_add_tail(&language->list, &opts->languages);
+ opts->nlangs++;
+ INIT_LIST_HEAD(&language->strings);
+
+ config_group_init_type_name(&language->group, name, &uvcg_language_type);
+
+ mutex_unlock(&opts->lock);
+
+ return &language->group;
+}
+
+static void uvcg_language_drop(struct config_group *group, struct config_item *item)
+{
+ struct uvcg_language *language;
+ struct config_item *opts_item;
+ struct f_uvc_opts *opts;
+
+ language = to_uvcg_language(to_config_group(item));
+
+ opts_item = group->cg_item.ci_parent;
+ opts = to_f_uvc_opts(opts_item);
+
+ mutex_lock(&opts->lock);
+
+ list_del(&language->list);
+ config_item_put(item);
+
+ mutex_unlock(&opts->lock);
+}
+
+static struct configfs_group_operations uvcg_strings_grp_ops = {
+ .make_group = uvcg_language_make,
+ .drop_item = uvcg_language_drop,
+};
+
+static const struct uvcg_config_group_type uvcg_strings_grp_type = {
+ .type = {
+ .ct_item_ops = &uvcg_config_item_ops,
+ .ct_group_ops = &uvcg_strings_grp_ops,
+ .ct_owner = THIS_MODULE,
+ },
+ .name = "strings",
+};
+
/* -----------------------------------------------------------------------------
* UVC function
*/
@@ -2951,6 +3252,7 @@ static const struct uvcg_config_group_type uvc_func_type = {
.children = (const struct uvcg_config_group_type*[]) {
&uvcg_control_grp_type,
&uvcg_streaming_grp_type,
+ &uvcg_strings_grp_type,
NULL,
},
};
diff --git a/drivers/usb/gadget/function/uvc_configfs.h b/drivers/usb/gadget/function/uvc_configfs.h
index c9a4182fb26f..a714426a174a 100644
--- a/drivers/usb/gadget/function/uvc_configfs.h
+++ b/drivers/usb/gadget/function/uvc_configfs.h
@@ -13,6 +13,7 @@
#define UVC_CONFIGFS_H
#include <linux/configfs.h>
+#include <linux/usb/gadget.h>
#include "u_uvc.h"
@@ -132,6 +133,35 @@ static inline struct uvcg_mjpeg *to_uvcg_mjpeg(struct config_item *item)
return container_of(to_uvcg_format(item), struct uvcg_mjpeg, fmt);
}
+/* -----------------------------------------------------------------------------
+ * strings/
+ */
+
+struct uvcg_language {
+ struct config_group group;
+ unsigned int nstrings;
+ struct list_head list;
+ struct list_head strings;
+ struct usb_gadget_strings stringtab;
+};
+
+#define to_uvcg_language(language) \
+container_of(language, struct uvcg_language, group)
+
+/* -----------------------------------------------------------------------------
+ * strings/<LANGID>
+ */
+
+struct uvcg_string {
+ struct config_item item;
+ struct list_head list;
+ char string[USB_MAX_STRING_LEN];
+ struct usb_string usb_string;
+};
+
+#define to_uvcg_string(str_item)\
+container_of(str_item, struct uvcg_string, item)
+
/* -----------------------------------------------------------------------------
* control/extensions/<NAME>
*/
--
2.34.1
