usb: dwc2: method of switching usb speed

1, hardware feature
high speed:
host A only support high speed, does not support keyboard/mouse
otg host support all speed, including keyboard/mouse

full speed:
Both host A and otg host only support full/low speed.

2. If user want to support full speed.
mount -t debugfs none /mnt
cd /mnt/f72c0000.usb/
cat config
echo 1 > config /* switch to full speed */
echo 0 > config /* switch to high speed */

Then unplug usb, host mode will switch to full speed, all ports don't support high speed in host mode.
Every time switch speed, just need plug usb -> unplug usb.

For example:
mount -t debugfs none /mnt
cd /mnt/f72c0000.usb/
cat config
 input para should be:
 0, HIGH speed;
 1, FULL speed
 Current speed=0: HIGH speed

If unplug usb and insert mouse now, it will fail.
 usb 1-1-port1: unable to enumerate USB device

echo 1 > config
 Current speed=1: FULL speed
cat config
 input para should be:
  0, HIGH speed;
  1, FULL speed
 Current speed=1: FULL speed

If unplug usb and insert mouse now
 usb 1-1.1: new low-speed USB device number 8 using dwc2

Signed-off-by: Zhangfei Gao <zhangfei.gao@linaro.org>

2 files changed, 43 insertions, 0 deletions

diff --git a/drivers/usb/dwc2/core.h b/drivers/usb/dwc2/core.h
index f74304b12652..0664631fed5b 100644
--- a/drivers/usb/dwc2/core.h
+++ b/drivers/usb/dwc2/core.h
@@ -616,6 +616,7 @@ struct dwc2_hsotg {
 	struct dentry *debug_file;
 	struct dentry *debug_testmode;
 	struct dentry *debug_fifo;
+	struct dentry *debug_config;
 
 	/* DWC OTG HW Release versions */
 #define DWC2_CORE_REV_2_71a	0x4f54271a
diff --git a/drivers/usb/dwc2/gadget.c b/drivers/usb/dwc2/gadget.c
index 364cd9614fe7..7818b32f0bbc 100644
--- a/drivers/usb/dwc2/gadget.c
+++ b/drivers/usb/dwc2/gadget.c
@@ -3689,6 +3689,41 @@ static const struct file_operations ep_fops = {
 	.release	= single_release,
 };
 
+static int config_fops_get(void *data, u64 *speed)
+{
+	struct dwc2_hsotg *hsotg = data;
+
+	pr_info("input para should be:\n 0, HIGH speed;\n 1, FULL speed\n");
+	if (hsotg->core_params->speed)
+		pr_info("Current speed=%d: FULL speed\n",
+			hsotg->core_params->speed);
+	else
+		pr_info("Current speed=%d: HIGH speed\n",
+			hsotg->core_params->speed);
+	*speed = hsotg->core_params->speed;
+
+	return 0;
+};
+
+static int config_fops_set(void *data, u64 speed)
+{
+	struct dwc2_hsotg *hsotg = data;
+
+	if (hsotg->core_params->speed != speed)
+		hsotg->core_params->speed = speed;
+
+	if (hsotg->core_params->speed)
+		pr_info("Current speed=%d: FULL speed\n",
+			hsotg->core_params->speed);
+	else
+		pr_info("Current speed=%d: HIGH speed\n",
+			hsotg->core_params->speed);
+	return 0;
+};
+
+DEFINE_SIMPLE_ATTRIBUTE(config_fops, config_fops_get,
+			config_fops_set, "%llu\n");
+
 /**
  * s3c_hsotg_create_debug - create debugfs directory and files
  * @hsotg: The driver state
@@ -3712,6 +3747,12 @@ static void s3c_hsotg_create_debug(struct dwc2_hsotg *hsotg)
 
 	/* create general state file */
 
+	hsotg->debug_config = debugfs_create_file("config", S_IWUSR | S_IRUGO,
+						  root,	hsotg, &config_fops);
+
+	if (IS_ERR(hsotg->debug_config))
+		dev_err(hsotg->dev, "%s: failed to create config\n", __func__);
+
 	hsotg->debug_file = debugfs_create_file("state", S_IRUGO, root,
 						hsotg, &state_fops);
 
@@ -3781,6 +3822,7 @@ static void s3c_hsotg_delete_debug(struct dwc2_hsotg *hsotg)
 
 	debugfs_remove(hsotg->debug_file);
 	debugfs_remove(hsotg->debug_testmode);
+	debugfs_remove(hsotg->debug_config);
 	debugfs_remove(hsotg->debug_fifo);
 	debugfs_remove(hsotg->debug_root);
 }