[PATCH 10/10] usb: gadget: function: Add Generic USB Display support

Noralf Trønnes
2020-04-29T12:58:02Z

This adds the gadget side support for the Generic USB Display. It presents
a DRM display device as a USB Display configured through configfs.

The display is implemented as a vendor type USB interface with one bulk
out endpoint. The protocol is implemented using control requests.
lz4 compressed framebuffer data/pixels are sent over the bulk endpoint.

The DRM part of the gadget is placed in the DRM subsystem since it reaches
into the DRM internals.

Cc: Felipe Balbi <balbi@kernel.org>
Signed-off-by: Noralf Trønnes <noralf@tronnes.org>
---
.../ABI/testing/configfs-usb-gadget-gud_drm | 10 +
MAINTAINERS | 2 +
drivers/usb/gadget/Kconfig | 12 +
drivers/usb/gadget/function/Makefile | 2 +
drivers/usb/gadget/function/f_gud_drm.c | 678 ++++++++++++++++++
5 files changed, 704 insertions(+)
create mode 100644 Documentation/ABI/testing/configfs-usb-gadget-gud_drm
create mode 100644 drivers/usb/gadget/function/f_gud_drm.c

diff --git a/Documentation/ABI/testing/configfs-usb-gadget-gud_drm b/Documentation/ABI/testing/configfs-usb-gadget-gud_drm
new file mode 100644
index 000000000000..d6d802c16eeb
--- /dev/null
+++ b/Documentation/ABI/testing/configfs-usb-gadget-gud_drm
@@ -0,0 +1,10 @@
+What: /config/usb-gadget/gadget/functions/gud_drm.name
+Date: Apr 2020
+KernelVersion: 5.8
+Description:
+ The attributes:
+
+ drm_dev - DRM device number
+ backlight_dev - Backlight device name (optional)
+ The backlight brightness scale should be
+ perceptual not linear.
diff --git a/MAINTAINERS b/MAINTAINERS
index bb4609984e9a..fe56c68beb11 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -5287,7 +5287,9 @@ M: Noralf Trønnes <noralf@tronnes.org>
S: Maintained
W: https://github.com/notro/gud/wiki
T: git git://anongit.freedesktop.org/drm/drm-misc
+F: Documentation/ABI/testing/configfs-usb-gadget-gud_drm
F: drivers/gpu/drm/gud/
+F: drivers/usb/gadget/function/f_gud_drm.c
F: include/drm/gud_drm.h

DRM DRIVER FOR GRAIN MEDIA GM12U320 PROJECTORS
diff --git a/drivers/usb/gadget/Kconfig b/drivers/usb/gadget/Kconfig
index c6db0a0a340c..8d90add495b6 100644
--- a/drivers/usb/gadget/Kconfig
+++ b/drivers/usb/gadget/Kconfig
@@ -216,6 +216,9 @@ config USB_F_PRINTER
config USB_F_TCM
tristate

+config USB_F_GUD_DRM
+ tristate
+
# this first set of drivers all depend on bulk-capable hardware.

config USB_CONFIGFS
@@ -483,6 +486,15 @@ config USB_CONFIGFS_F_TCM
Both protocols can work on USB2.0 and USB3.0.
UAS utilizes the USB 3.0 feature called streams support.

+config USB_CONFIGFS_F_GUD_DRM
+ bool "Generic USB Display Gadget function"
+ depends on USB_CONFIGFS
+ depends on DRM
+ select DRM_GUD_GADGET
+ select USB_F_GUD_DRM
+ help
+ This presents a DRM display device as a Generic USB Display.
+
source "drivers/usb/gadget/legacy/Kconfig"

endif # USB_GADGET
diff --git a/drivers/usb/gadget/function/Makefile b/drivers/usb/gadget/function/Makefile
index 5d3a6cf02218..cd71caa2a34c 100644
--- a/drivers/usb/gadget/function/Makefile
+++ b/drivers/usb/gadget/function/Makefile
@@ -50,3 +50,5 @@ usb_f_printer-y := f_printer.o
obj-$(CONFIG_USB_F_PRINTER) += usb_f_printer.o
usb_f_tcm-y := f_tcm.o
obj-$(CONFIG_USB_F_TCM) += usb_f_tcm.o
+usb_f_gud_drm-y := f_gud_drm.o
+obj-$(CONFIG_USB_F_GUD_DRM) += usb_f_gud_drm.o
diff --git a/drivers/usb/gadget/function/f_gud_drm.c b/drivers/usb/gadget/function/f_gud_drm.c
new file mode 100644
index 000000000000..9a2d6bb9739f
--- /dev/null
+++ b/drivers/usb/gadget/function/f_gud_drm.c
@@ -0,0 +1,678 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2020 Noralf Trønnes
+ */
+
+#include <linux/configfs.h>
+#include <linux/device.h>
+#include <linux/kernel.h>
+#include <linux/list.h>
+#include <linux/module.h>
+#include <linux/mutex.h>
+#include <linux/slab.h>
+#include <linux/spinlock.h>
+#include <linux/usb/composite.h>
+#include <linux/usb/gadget.h>
+#include <linux/workqueue.h>
+
+#include <drm/gud_drm.h>
+
+struct f_gud_drm {
+ struct usb_function func;
+ struct work_struct worker;
+ size_t max_buffer_size;
+ void *ctrl_req_buf;
+
+ u8 interface_id;
+ struct usb_request *ctrl_req;
+
+ struct usb_ep *bulk_ep;
+ struct usb_request *bulk_req;
+
+ struct gud_drm_gadget *gdg;
+
+ spinlock_t lock; /* Protects the following members: */
+ bool ctrl_pending;
+ bool status_pending;
+ bool bulk_pending;
+ bool disable_pending;
+ u8 errno;
+ u16 request;
+ u16 value;
+};
+
+static inline struct f_gud_drm *func_to_f_gud_drm(struct usb_function *f)
+{
+ return container_of(f, struct f_gud_drm, func);
+}
+
+struct f_gud_drm_opts {
+ struct usb_function_instance func_inst;
+ struct mutex lock;
+ int refcnt;
+
+ unsigned int drm_dev;
+ const char *backlight_dev;
+};
+
+static inline struct f_gud_drm_opts *fi_to_f_gud_drm_opts(const struct usb_function_instance *fi)
+{
+ return container_of(fi, struct f_gud_drm_opts, func_inst);
+}
+
+static inline struct f_gud_drm_opts *ci_to_f_gud_drm_opts(struct config_item *item)
+{
+ return container_of(to_config_group(item), struct f_gud_drm_opts,
+ func_inst.group);
+}
+
+#define F_MUD_DEFINE_BULK_ENDPOINT_DESCRIPTOR(name, addr, size) \
+ static struct usb_endpoint_descriptor name = { \
+ .bLength = USB_DT_ENDPOINT_SIZE, \
+ .bDescriptorType = USB_DT_ENDPOINT, \
+ .bEndpointAddress = addr, \
+ .bmAttributes = USB_ENDPOINT_XFER_BULK, \
+ .wMaxPacketSize = cpu_to_le16(size), \
+ }
+
+static struct usb_interface_descriptor f_gud_drm_intf = {
+ .bLength = USB_DT_INTERFACE_SIZE,
+ .bDescriptorType = USB_DT_INTERFACE,
+ .bNumEndpoints = 1,
+ .bInterfaceClass = USB_CLASS_VENDOR_SPEC,
+};
+
+F_MUD_DEFINE_BULK_ENDPOINT_DESCRIPTOR(f_gud_drm_fs_out_desc, USB_DIR_OUT, 0);
+
+static struct usb_descriptor_header *f_gud_drm_fs_function[] = {
+ (struct usb_descriptor_header *)&f_gud_drm_intf,
+ (struct usb_descriptor_header *)&f_gud_drm_fs_out_desc,
+ NULL,
+};
+
+F_MUD_DEFINE_BULK_ENDPOINT_DESCRIPTOR(f_gud_drm_hs_out_desc, USB_DIR_OUT, 512);
+
+static struct usb_descriptor_header *f_gud_drm_hs_function[] = {
+ (struct usb_descriptor_header *)&f_gud_drm_intf,
+ (struct usb_descriptor_header *)&f_gud_drm_hs_out_desc,
+ NULL,
+};
+
+F_MUD_DEFINE_BULK_ENDPOINT_DESCRIPTOR(f_gud_drm_ss_out_desc, USB_DIR_OUT, 1024);
+
+static struct usb_ss_ep_comp_descriptor f_gud_drm_ss_bulk_comp_desc = {
+ .bLength = USB_DT_SS_EP_COMP_SIZE,
+ .bDescriptorType = USB_DT_SS_ENDPOINT_COMP,
+};
+
+static struct usb_descriptor_header *f_gud_drm_ss_function[] = {
+ (struct usb_descriptor_header *)&f_gud_drm_intf,
+ (struct usb_descriptor_header *)&f_gud_drm_ss_out_desc,
+ (struct usb_descriptor_header *)&f_gud_drm_ss_bulk_comp_desc,
+ NULL,
+};
+
+static struct usb_string f_gud_drm_string_defs[] = {
+ [0].s = "Generic USB Display",
+ { } /* end of list */
+};
+
+static struct usb_gadget_strings f_gud_drm_string_table = {
+ .language = 0x0409, /* en-us */
+ .strings = f_gud_drm_string_defs,
+};
+
+static struct usb_gadget_strings *f_gud_drm_strings[] = {
+ &f_gud_drm_string_table,
+ NULL,
+};
+
+static void f_gud_drm_bulk_complete(struct usb_ep *ep, struct usb_request *req)
+{
+ struct f_gud_drm *fgd = req->context;
+ unsigned long flags;
+
+ if (req->status || req->actual != req->length)
+ return;
+
+ spin_lock_irqsave(&fgd->lock, flags);
+ fgd->bulk_pending = true;
+ spin_unlock_irqrestore(&fgd->lock, flags);
+
+ queue_work(system_long_wq, &fgd->worker);
+}
+
+static int f_gud_drm_ctrl_req_set_buffer(struct f_gud_drm *fgd, void *buf, size_t len)
+{
+ int ret;
+
+ if (len != sizeof(struct gud_drm_req_set_buffer))
+ return -EINVAL;
+
+ ret = gud_drm_gadget_set_buffer(fgd->gdg, buf);
+ if (ret < 0)
+ return ret;
+
+ if (ret > fgd->max_buffer_size)
+ return -EOVERFLOW;
+
+ fgd->bulk_req->length = ret;
+
+ return usb_ep_queue(fgd->bulk_ep, fgd->bulk_req, GFP_KERNEL);
+}
+
+static void f_gud_drm_worker(struct work_struct *work)
+{
+ struct f_gud_drm *fgd = container_of(work, struct f_gud_drm, worker);
+ bool ctrl_pending, bulk_pending, disable_pending;
+ struct gud_drm_gadget *gdg = fgd->gdg;
+ unsigned long flags;
+ u16 request, value;
+ int ret;
+
+ spin_lock_irqsave(&fgd->lock, flags);
+ request = fgd->request;
+ value = fgd->value;
+ ctrl_pending = fgd->ctrl_pending;
+ bulk_pending = fgd->bulk_pending;
+ disable_pending = fgd->disable_pending;
+ spin_unlock_irqrestore(&fgd->lock, flags);
+
+ pr_debug("%s: bulk_pending=%u ctrl_pending=%u disable_pending=%u\n",
+ __func__, bulk_pending, ctrl_pending, disable_pending);
+
+ if (disable_pending) {
+ gud_drm_gadget_disable_pipe(gdg);
+
+ spin_lock_irqsave(&fgd->lock, flags);
+ fgd->disable_pending = false;
+ spin_unlock_irqrestore(&fgd->lock, flags);
+ return;
+ }
+
+ if (bulk_pending) {
+ struct usb_request *req = fgd->bulk_req;
+
+ ret = gud_drm_gadget_write_buffer(gdg, req->buf, req->actual);
+ if (ret)
+ pr_err("%s: Failed to write buffer, error=%d\n", __func__, ret);
+
+ spin_lock_irqsave(&fgd->lock, flags);
+ fgd->bulk_pending = false;
+ spin_unlock_irqrestore(&fgd->lock, flags);
+ }
+
+ if (ctrl_pending) {
+ unsigned int length = fgd->ctrl_req->length;
+ void *buf = fgd->ctrl_req->buf;
+
+ if (request == GUD_DRM_USB_REQ_SET_BUFFER)
+ ret = f_gud_drm_ctrl_req_set_buffer(fgd, buf, length);
+ else
+ ret = gud_drm_gadget_ctrl_set(gdg, request, value, buf, length);
+
+ spin_lock_irqsave(&fgd->lock, flags);
+ if (!fgd->errno) /* Don't scribble over an EBUSY or ESHUTDOWN */
+ fgd->errno = -ret;
+ fgd->ctrl_pending = false;
+ fgd->status_pending = false;
+ spin_unlock_irqrestore(&fgd->lock, flags);
+ }
+}
+
+static void f_gud_drm_ctrl_req_complete(struct usb_ep *ep, struct usb_request *req)
+{
+ struct f_gud_drm *fgd = req->context;
+ unsigned long flags;
+ int ret = 0;
+
+ spin_lock_irqsave(&fgd->lock, flags);
+
+ if (req->status)
+ ret = req->status;
+ else if (req->actual != req->length)
+ ret = -EREMOTEIO;
+ if (ret) {
+ fgd->errno = -ret;
+ fgd->status_pending = false;
+ } else {
+ fgd->ctrl_pending = true;
+ }
+
+ spin_unlock_irqrestore(&fgd->lock, flags);
+
+ if (!ret)
+ queue_work(system_long_wq, &fgd->worker);
+}
+
+static int f_gud_drm_setup(struct usb_function *f, const struct usb_ctrlrequest *ctrl)
+{
+ struct usb_composite_dev *cdev = f->config->cdev;
+ struct f_gud_drm *fgd = func_to_f_gud_drm(f);
+ bool in = ctrl->bRequestType & USB_DIR_IN;
+ u16 length = le16_to_cpu(ctrl->wLength);
+ u16 value = le16_to_cpu(ctrl->wValue);
+ unsigned long flags;
+ int ret;
+
+ if (ctrl->bRequest == USB_REQ_GET_STATUS) {
+ struct gud_drm_req_get_status *status = cdev->req->buf;
+
+ if (!in || length != sizeof(*status))
+ return -EINVAL;
+
+ spin_lock_irqsave(&fgd->lock, flags);
+ status->flags = 0;
+ if (fgd->status_pending)
+ status->flags |= GUD_DRM_STATUS_PENDING;
+ status->errno = fgd->errno;
+ spin_unlock_irqrestore(&fgd->lock, flags);
+ } else if (in) {
+ if (length > USB_COMP_EP0_BUFSIZ) /* 4k */
+ return -EOVERFLOW;
+
+ ret = gud_drm_gadget_ctrl_get(fgd->gdg, ctrl->bRequest, value,
+ cdev->req->buf, length);
+ spin_lock_irqsave(&fgd->lock, flags);
+ fgd->status_pending = false;
+ fgd->errno = ret < 0 ? -ret : 0;
+ spin_unlock_irqrestore(&fgd->lock, flags);
+ if (ret < 0)
+ return ret;
+
+ length = ret;
+ } else {
+ if (length > GUD_DRM_MAX_TRANSFER_SIZE)
+ return -EOVERFLOW;
+
+ spin_lock_irqsave(&fgd->lock, flags);
+ if (fgd->ctrl_pending) {
+ /* If we get here the host has timed out on the previous request */
+ ret = -EBUSY;
+ fgd->status_pending = false;
+ fgd->errno = -ret;
+ } else {
+ ret = 0;
+ fgd->errno = 0;
+ fgd->request = ctrl->bRequest;
+ fgd->value = value;
+ fgd->status_pending = true;
+ }
+ spin_unlock_irqrestore(&fgd->lock, flags);
+
+ if (ret)
+ return ret;
+
+ fgd->ctrl_req->length = length;
+
+ return usb_ep_queue(cdev->gadget->ep0, fgd->ctrl_req, GFP_ATOMIC);
+ }
+
+ cdev->req->length = length;
+
+ return usb_ep_queue(cdev->gadget->ep0, cdev->req, GFP_ATOMIC);
+}
+
+static bool f_gud_drm_req_match(struct usb_function *f, const struct usb_ctrlrequest *ctrl,
+ bool config0)
+{
+ struct f_gud_drm *fgd = func_to_f_gud_drm(f);
+
+ if (config0)
+ return false;
+
+ if ((ctrl->bRequestType & USB_TYPE_MASK) != USB_TYPE_VENDOR)
+ return false;
+
+ if ((ctrl->bRequestType & USB_RECIP_MASK) != USB_RECIP_INTERFACE)
+ return false;
+
+ return fgd->interface_id == le16_to_cpu(ctrl->wIndex);
+}
+
+static int f_gud_drm_set_alt(struct usb_function *f, unsigned int intf, unsigned int alt)
+{
+ struct usb_composite_dev *cdev = f->config->cdev;
+ struct f_gud_drm *fgd = func_to_f_gud_drm(f);
+ unsigned long flags;
+
+ if (alt || intf != fgd->interface_id)
+ return -EINVAL;
+
+ if (!fgd->bulk_ep->desc) {
+ pr_debug("%s: init\n", __func__);
+ if (config_ep_by_speed(cdev->gadget, f, fgd->bulk_ep)) {
+ fgd->bulk_ep->desc = NULL;
+ return -EINVAL;
+ }
+ }
+
+ pr_debug("%s: reset\n", __func__);
+
+ usb_ep_disable(fgd->bulk_ep);
+ usb_ep_enable(fgd->bulk_ep);
+
+ spin_lock_irqsave(&fgd->lock, flags);
+ fgd->ctrl_pending = false;
+ fgd->bulk_pending = false;
+ fgd->disable_pending = false;
+ spin_unlock_irqrestore(&fgd->lock, flags);
+
+ return 0;
+}
+
+static void f_gud_drm_disable(struct usb_function *f)
+{
+ struct f_gud_drm *fgd = func_to_f_gud_drm(f);
+ unsigned long flags;
+
+ pr_debug("%s\n", __func__);
+
+ usb_ep_disable(fgd->bulk_ep);
+
+ spin_lock_irqsave(&fgd->lock, flags);
+ fgd->ctrl_pending = false;
+ fgd->bulk_pending = false;
+ fgd->status_pending = false;
+ fgd->disable_pending = true;
+ fgd->errno = ESHUTDOWN;
+ spin_unlock_irqrestore(&fgd->lock, flags);
+
+ queue_work(system_long_wq, &fgd->worker);
+}
+
+static void f_gud_drm_unbind(struct usb_configuration *c, struct usb_function *f)
+{
+ struct f_gud_drm *fgd = func_to_f_gud_drm(f);
+ struct usb_composite_dev *cdev = fgd->func.config->cdev;
+
+ flush_work(&fgd->worker);
+
+ gud_drm_gadget_fini(fgd->gdg);
+ fgd->gdg = NULL;
+
+ kfree(fgd->bulk_req->buf);
+ usb_ep_free_request(fgd->bulk_ep, fgd->bulk_req);
+ usb_ep_free_request(cdev->gadget->ep0, fgd->ctrl_req);
+ fgd->ctrl_req = NULL;
+ fgd->bulk_req = NULL;
+ fgd->bulk_ep = NULL;
+
+ usb_free_all_descriptors(f);
+}
+
+static int f_gud_drm_bind(struct usb_configuration *c, struct usb_function *f)
+{
+ struct f_gud_drm_opts *opts = fi_to_f_gud_drm_opts(f->fi);
+ struct usb_composite_dev *cdev = c->cdev;
+ struct f_gud_drm *fgd = func_to_f_gud_drm(f);
+ struct usb_request *ctrl_req, *bulk_req;
+ struct gud_drm_gadget *gdg;
+ struct usb_string *us;
+ void *buf;
+ int ret;
+
+ us = usb_gstrings_attach(cdev, f_gud_drm_strings,
+ ARRAY_SIZE(f_gud_drm_string_defs));
+ if (IS_ERR(us))
+ return PTR_ERR(us);
+
+ f_gud_drm_intf.iInterface = us[0].id;
+
+ ret = usb_interface_id(c, f);
+ if (ret < 0)
+ return ret;
+
+ fgd->interface_id = ret;
+ f_gud_drm_intf.bInterfaceNumber = fgd->interface_id;
+
+ fgd->bulk_ep = usb_ep_autoconfig(cdev->gadget, &f_gud_drm_fs_out_desc);
+ if (!fgd->bulk_ep)
+ return -ENODEV;
+
+ f_gud_drm_hs_out_desc.bEndpointAddress = f_gud_drm_fs_out_desc.bEndpointAddress;
+
+ f_gud_drm_ss_out_desc.bEndpointAddress = f_gud_drm_fs_out_desc.bEndpointAddress;
+
+ ret = usb_assign_descriptors(f, f_gud_drm_fs_function, f_gud_drm_hs_function,
+ f_gud_drm_ss_function, NULL);
+ if (ret)
+ return ret;
+
+ ctrl_req = usb_ep_alloc_request(cdev->gadget->ep0, GFP_KERNEL);
+ if (!ctrl_req) {
+ ret = -ENOMEM;
+ goto fail_free_descs;
+ }
+
+ ctrl_req->buf = fgd->ctrl_req_buf;
+ ctrl_req->complete = f_gud_drm_ctrl_req_complete;
+ ctrl_req->context = fgd;
+
+ gdg = gud_drm_gadget_init(opts->drm_dev, opts->backlight_dev, &fgd->max_buffer_size);
+ if (IS_ERR(gdg)) {
+ ret = PTR_ERR(gdg);
+ goto fail_free_ctrl_req;
+ }
+
+ bulk_req = usb_ep_alloc_request(fgd->bulk_ep, GFP_KERNEL);
+ if (!bulk_req) {
+ ret = -ENOMEM;
+ goto fail_free_ctrl_req;
+ }
+
+ buf = kmalloc(fgd->max_buffer_size, GFP_KERNEL);
+ if (!buf) {
+ ret = -ENOMEM;
+ goto fail_free_bulk_req;
+ }
+
+ bulk_req->complete = f_gud_drm_bulk_complete;
+ bulk_req->context = fgd;
+ bulk_req->buf = buf;
+
+ fgd->ctrl_req = ctrl_req;
+ fgd->bulk_req = bulk_req;
+ fgd->gdg = gdg;
+
+ return 0;
+
+fail_free_bulk_req:
+ usb_ep_free_request(fgd->bulk_ep, bulk_req);
+fail_free_ctrl_req:
+ usb_ep_free_request(cdev->gadget->ep0, ctrl_req);
+fail_free_descs:
+ usb_free_all_descriptors(f);
+
+ return ret;
+}
+
+static void f_gud_drm_free_func(struct usb_function *f)
+{
+ struct f_gud_drm_opts *opts = container_of(f->fi, struct f_gud_drm_opts, func_inst);
+ struct f_gud_drm *fgd = func_to_f_gud_drm(f);
+
+ mutex_lock(&opts->lock);
+ opts->refcnt--;
+ mutex_unlock(&opts->lock);
+
+ kfree(fgd->ctrl_req_buf);
+ kfree(fgd);
+}
+
+static struct usb_function *f_gud_drm_alloc_func(struct usb_function_instance *fi)
+{
+ struct f_gud_drm_opts *opts = fi_to_f_gud_drm_opts(fi);
+ struct usb_function *func;
+ struct f_gud_drm *fgd;
+
+ fgd = kzalloc(sizeof(*fgd), GFP_KERNEL);
+ if (!fgd)
+ return ERR_PTR(-ENOMEM);
+
+ fgd->ctrl_req_buf = kmalloc(GUD_DRM_MAX_TRANSFER_SIZE, GFP_KERNEL);
+ if (!fgd->ctrl_req_buf)
+ goto error;
+
+ spin_lock_init(&fgd->lock);
+ INIT_WORK(&fgd->worker, f_gud_drm_worker);
+
+ mutex_lock(&opts->lock);
+ opts->refcnt++;
+ mutex_unlock(&opts->lock);
+
+ func = &fgd->func;
+ func->name = "gud_drm";
+ func->bind = f_gud_drm_bind;
+ func->unbind = f_gud_drm_unbind;
+ func->set_alt = f_gud_drm_set_alt;
+ func->req_match = f_gud_drm_req_match;
+ func->setup = f_gud_drm_setup;
+ func->disable = f_gud_drm_disable;
+ func->free_func = f_gud_drm_free_func;
+
+ return func;
+
+error:
+ kfree(fgd);
+
+ return ERR_PTR(-ENOMEM);
+}
+
+static ssize_t f_gud_drm_opts_drm_dev_show(struct config_item *item, char *page)
+{
+ struct f_gud_drm_opts *opts = ci_to_f_gud_drm_opts(item);
+ int result;
+
+ mutex_lock(&opts->lock);
+ result = sprintf(page, "%u\n", opts->drm_dev);
+ mutex_unlock(&opts->lock);
+
+ return result;
+}
+
+static ssize_t f_gud_drm_opts_drm_dev_store(struct config_item *item,
+ const char *page, size_t len)
+{
+ struct f_gud_drm_opts *opts = ci_to_f_gud_drm_opts(item);
+ unsigned int num;
+ int ret;
+
+ mutex_lock(&opts->lock);
+ if (opts->refcnt) {
+ ret = -EBUSY;
+ goto unlock;
+ }
+
+ ret = kstrtouint(page, 0, &num);
+ if (ret)
+ goto unlock;
+
+ opts->drm_dev = num;
+ ret = len;
+unlock:
+ mutex_unlock(&opts->lock);
+
+ return ret;
+}
+
+CONFIGFS_ATTR(f_gud_drm_opts_, drm_dev);
+
+static ssize_t f_gud_drm_opts_backlight_dev_show(struct config_item *item, char *page)
+{
+ struct f_gud_drm_opts *opts = ci_to_f_gud_drm_opts(item);
+ ssize_t ret = 0;
+
+ mutex_lock(&opts->lock);
+ if (opts->backlight_dev)
+ ret = strscpy(page, opts->backlight_dev, PAGE_SIZE);
+ else
+ page[0] = '\0';
+ mutex_unlock(&opts->lock);
+
+ return ret;
+}
+
+static ssize_t f_gud_drm_opts_backlight_dev_store(struct config_item *item,
+ const char *page, size_t len)
+{
+ struct f_gud_drm_opts *opts = ci_to_f_gud_drm_opts(item);
+ ssize_t ret;
+ char *name;
+
+ mutex_lock(&opts->lock);
+ if (opts->refcnt) {
+ ret = -EBUSY;
+ goto unlock;
+ }
+
+ name = kstrndup(page, len, GFP_KERNEL);
+ if (!name) {
+ ret = -ENOMEM;
+ goto unlock;
+ }
+
+ kfree(opts->backlight_dev);
+ opts->backlight_dev = name;
+ ret = len;
+unlock:
+ mutex_unlock(&opts->lock);
+
+ return ret;
+}
+
+CONFIGFS_ATTR(f_gud_drm_opts_, backlight_dev);
+
+static struct configfs_attribute *f_gud_drm_attrs[] = {
+ &f_gud_drm_opts_attr_drm_dev,
+ &f_gud_drm_opts_attr_backlight_dev,
+ NULL,
+};
+
+static void f_gud_drm_attr_release(struct config_item *item)
+{
+ struct f_gud_drm_opts *opts = ci_to_f_gud_drm_opts(item);
+
+ usb_put_function_instance(&opts->func_inst);
+}
+
+static struct configfs_item_operations f_gud_drm_item_ops = {
+ .release = f_gud_drm_attr_release,
+};
+
+static const struct config_item_type f_gud_drm_func_type = {
+ .ct_item_ops = &f_gud_drm_item_ops,
+ .ct_attrs = f_gud_drm_attrs,
+ .ct_owner = THIS_MODULE,
+};
+
+static void f_gud_drm_free_func_inst(struct usb_function_instance *fi)
+{
+ struct f_gud_drm_opts *opts = fi_to_f_gud_drm_opts(fi);
+
+ mutex_destroy(&opts->lock);
+ kfree(opts->backlight_dev);
+ kfree(opts);
+}
+
+static struct usb_function_instance *f_gud_drm_alloc_func_inst(void)
+{
+ struct f_gud_drm_opts *opts;
+
+ opts = kzalloc(sizeof(*opts), GFP_KERNEL);
+ if (!opts)
+ return ERR_PTR(-ENOMEM);
+
+ mutex_init(&opts->lock);
+ opts->func_inst.free_func_inst = f_gud_drm_free_func_inst;
+
+ config_group_init_type_name(&opts->func_inst.group, "", &f_gud_drm_func_type);
+
+ return &opts->func_inst;
+}
+
+DECLARE_USB_FUNCTION_INIT(gud_drm, f_gud_drm_alloc_func_inst, f_gud_drm_alloc_func);
+
+MODULE_DESCRIPTION("Generic USB Display Gadget");
+MODULE_AUTHOR("Noralf Trønnes");
+MODULE_LICENSE("GPL");
--
2.23.0