Hi Dan,
Thank you for the patch.
On Mon, Nov 21, 2022 at 09:25:13AM +0000, Daniel Scally wrote:
> 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.
Hmmmm... Is this something that should be specific to the UVC gadget, or
should it be a core gadget helper ?
> 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>
> */
--
Regards,
Laurent Pinchart
