usb: gadget: printer: add configfs support

Add support for configfs interface so that f_printer can be used as a
component of usb gadgets composed with it.

Signed-off-by: Andrzej Pietrasiewicz <andrzej.p@samsung.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>
This commit is contained in:
Andrzej Pietrasiewicz 2015-03-03 10:52:32 +01:00 committed by Felipe Balbi
parent a2a8e48a94
commit ee1cd515e8
5 changed files with 204 additions and 2 deletions

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@ -0,0 +1,9 @@
What: /config/usb-gadget/gadget/functions/printer.name
Date: Apr 2015
KernelVersion: 4.1
Description:
The attributes:
pnp_string - Data to be passed to the host in pnp string
q_len - Number of requests per endpoint

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@ -19,6 +19,7 @@ provided by gadgets.
16. UAC1 function
17. UAC2 function
18. UVC function
19. PRINTER function
1. ACM function
@ -726,3 +727,49 @@ with these patches:
http://www.spinics.net/lists/linux-usb/msg99220.html
host: luvcview -f yuv
19. PRINTER function
====================
The function is provided by usb_f_printer.ko module.
Function-specific configfs interface
------------------------------------
The function name to use when creating the function directory is "printer".
The printer function provides these attributes in its function directory:
pnp_string - Data to be passed to the host in pnp string
q_len - Number of requests per endpoint
Testing the PRINTER function
----------------------------
The most basic testing:
device: run the gadget
# ls -l /devices/virtual/usb_printer_gadget/
should show g_printer<number>.
If udev is active, then /dev/g_printer<number> should appear automatically.
host:
If udev is active, then e.g. /dev/usb/lp0 should appear.
host->device transmission:
device:
# cat /dev/g_printer<number>
host:
# cat > /dev/usb/lp0
device->host transmission:
# cat > /dev/g_printer<number>
host:
# cat /dev/usb/lp0
More advanced testing can be done with the prn_example
described in Documentation/usb/gadget-printer.txt.

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@ -437,6 +437,19 @@ config USB_CONFIGFS_F_UVC
device. It provides a userspace API to process UVC control requests
and stream video data to the host.
config USB_CONFIGFS_F_PRINTER
bool "Printer function"
select USB_F_PRINTER
help
The Printer function channels data between the USB host and a
userspace program driving the print engine. The user space
program reads and writes the device file /dev/g_printer<X> to
receive or send printer data. It can use ioctl calls to
the device file to get or set printer status.
For more information, see Documentation/usb/gadget_printer.txt
which includes sample code for accessing the device file.
source "drivers/usb/gadget/legacy/Kconfig"
endchoice

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@ -1140,6 +1140,117 @@ static void printer_func_disable(struct usb_function *f)
spin_unlock_irqrestore(&dev->lock, flags);
}
static inline struct f_printer_opts
*to_f_printer_opts(struct config_item *item)
{
return container_of(to_config_group(item), struct f_printer_opts,
func_inst.group);
}
CONFIGFS_ATTR_STRUCT(f_printer_opts);
CONFIGFS_ATTR_OPS(f_printer_opts);
static void printer_attr_release(struct config_item *item)
{
struct f_printer_opts *opts = to_f_printer_opts(item);
usb_put_function_instance(&opts->func_inst);
}
static struct configfs_item_operations printer_item_ops = {
.release = printer_attr_release,
.show_attribute = f_printer_opts_attr_show,
.store_attribute = f_printer_opts_attr_store,
};
static ssize_t f_printer_opts_pnp_string_show(struct f_printer_opts *opts,
char *page)
{
int result;
mutex_lock(&opts->lock);
result = strlcpy(page, opts->pnp_string + 2, PNP_STRING_LEN - 2);
mutex_unlock(&opts->lock);
return result;
}
static ssize_t f_printer_opts_pnp_string_store(struct f_printer_opts *opts,
const char *page, size_t len)
{
int result, l;
mutex_lock(&opts->lock);
result = strlcpy(opts->pnp_string + 2, page, PNP_STRING_LEN - 2);
l = strlen(opts->pnp_string + 2) + 2;
opts->pnp_string[0] = (l >> 8) & 0xFF;
opts->pnp_string[1] = l & 0xFF;
mutex_unlock(&opts->lock);
return result;
}
static struct f_printer_opts_attribute f_printer_opts_pnp_string =
__CONFIGFS_ATTR(pnp_string, S_IRUGO | S_IWUSR,
f_printer_opts_pnp_string_show,
f_printer_opts_pnp_string_store);
static ssize_t f_printer_opts_q_len_show(struct f_printer_opts *opts,
char *page)
{
int result;
mutex_lock(&opts->lock);
result = sprintf(page, "%d\n", opts->q_len);
mutex_unlock(&opts->lock);
return result;
}
static ssize_t f_printer_opts_q_len_store(struct f_printer_opts *opts,
const char *page, size_t len)
{
int ret;
u16 num;
mutex_lock(&opts->lock);
if (opts->refcnt) {
ret = -EBUSY;
goto end;
}
ret = kstrtou16(page, 0, &num);
if (ret)
goto end;
if (num > 65535) {
ret = -EINVAL;
goto end;
}
opts->q_len = (unsigned)num;
ret = len;
end:
mutex_unlock(&opts->lock);
return ret;
}
static struct f_printer_opts_attribute f_printer_opts_q_len =
__CONFIGFS_ATTR(q_len, S_IRUGO | S_IWUSR, f_printer_opts_q_len_show,
f_printer_opts_q_len_store);
static struct configfs_attribute *printer_attrs[] = {
&f_printer_opts_pnp_string.attr,
&f_printer_opts_q_len.attr,
NULL,
};
static struct config_item_type printer_func_type = {
.ct_item_ops = &printer_item_ops,
.ct_attrs = printer_attrs,
.ct_owner = THIS_MODULE,
};
static inline int gprinter_get_minor(void)
{
return ida_simple_get(&printer_ida, 0, 0, GFP_KERNEL);
@ -1180,6 +1291,7 @@ static struct usb_function_instance *gprinter_alloc_inst(void)
if (!opts)
return ERR_PTR(-ENOMEM);
mutex_init(&opts->lock);
opts->func_inst.free_func_inst = gprinter_free_inst;
ret = &opts->func_inst;
@ -1201,6 +1313,8 @@ static struct usb_function_instance *gprinter_alloc_inst(void)
if (idr_is_empty(&printer_ida.idr))
gprinter_cleanup();
}
config_group_init_type_name(&opts->func_inst.group, "",
&printer_func_type);
unlock:
mutex_unlock(&printer_ida_lock);
@ -1210,8 +1324,13 @@ unlock:
static void gprinter_free(struct usb_function *f)
{
struct printer_dev *dev = func_to_printer(f);
struct f_printer_opts *opts;
opts = container_of(f->fi, struct f_printer_opts, func_inst);
kfree(dev);
mutex_lock(&opts->lock);
--opts->refcnt;
mutex_unlock(&opts->lock);
}
static void printer_func_unbind(struct usb_configuration *c,
@ -1265,16 +1384,23 @@ static struct usb_function *gprinter_alloc(struct usb_function_instance *fi)
opts = container_of(fi, struct f_printer_opts, func_inst);
if (opts->minor >= minors)
mutex_lock(&opts->lock);
if (opts->minor >= minors) {
mutex_unlock(&opts->lock);
return ERR_PTR(-ENOENT);
}
dev = kzalloc(sizeof(*dev), GFP_KERNEL);
if (!dev)
if (!dev) {
mutex_unlock(&opts->lock);
return ERR_PTR(-ENOMEM);
}
++opts->refcnt;
dev->minor = opts->minor;
dev->pnp_string = opts->pnp_string;
dev->q_len = opts->q_len;
mutex_unlock(&opts->lock);
dev->function.name = "printer";
dev->function.bind = printer_func_bind;

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@ -25,6 +25,13 @@ struct f_printer_opts {
int minor;
char pnp_string[PNP_STRING_LEN];
unsigned q_len;
/*
* Protect the data from concurrent access by read/write
* and create symlink/remove symlink
*/
struct mutex lock;
int refcnt;
};
#endif /* U_PRINTER_H */