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>

diff --git a/Documentation/ABI/testing/configfs-usb-gadget-printer b/Documentation/ABI/testing/configfs-usb-gadget-printer
new file mode 100644 (file)
index 0000000..6b0714e
--- /dev/null
+++ b/Documentation/ABI/testing/configfs-usb-gadget-printer
@@ -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
+

diff --git a/Documentation/usb/gadget-testing.txt b/Documentation/usb/gadget-testing.txt
index 076ac7ba7f935e03d6b37bd214ad53fa36ff472b..f45b2bf4b41dead903254b2c1ecc4d382505f1a3 100644 (file)
--- a/Documentation/usb/gadget-testing.txt
+++ b/Documentation/usb/gadget-testing.txt
@@ -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.

diff --git a/drivers/usb/gadget/Kconfig b/drivers/usb/gadget/Kconfig
index 9d507cf98f94f59fb7f8404ee9f267986f59992d..3bb0e67fded2053ad112ba78dceeb993bea164e0 100644 (file)
--- a/drivers/usb/gadget/Kconfig
+++ b/drivers/usb/gadget/Kconfig
@@ -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

diff --git a/drivers/usb/gadget/function/f_printer.c b/drivers/usb/gadget/function/f_printer.c
index 7afe17d76f17c2cdfb0acad0dfab3beb38447c00..757fcf070013c27e01cdd2e2a523b2daa0250cee 100644 (file)
--- a/drivers/usb/gadget/function/f_printer.c
+++ b/drivers/usb/gadget/function/f_printer.c
@@ -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 @@ static struct usb_function_instance *gprinter_alloc_inst(void)
 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;

diff --git a/drivers/usb/gadget/function/u_printer.h b/drivers/usb/gadget/function/u_printer.h
index b2338cacdfe483deac70e1cbb8f4476f09ffaedc..0e2c49d4274e403390c37d17358caefb733fcade 100644 (file)
--- a/drivers/usb/gadget/function/u_printer.h
+++ b/drivers/usb/gadget/function/u_printer.h
@@ -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 */