usb: dwc3: gadget: allow Link state changes via debugfs

This is very useful for low level link testing where
we might not have a USB Host stack, only a scope to
verify signal integrity.
Signed-off-by: Felipe Balbi <balbi@ti.com>

drivers/usb/dwc3/debugfs.c

@@ -549,6 +549,109 @@ static const struct file_operations dwc3_testmode_fops = {
 	.release		= single_release,
 };
 
+static int dwc3_link_state_show(struct seq_file *s, void *unused)
+{
+	struct dwc3		*dwc = s->private;
+	unsigned long		flags;
+	enum dwc3_link_state	state;
+	u32			reg;
+
+	spin_lock_irqsave(&dwc->lock, flags);
+	reg = dwc3_readl(dwc->regs, DWC3_DSTS);
+	state = DWC3_DSTS_USBLNKST(reg);
+	spin_unlock_irqrestore(&dwc->lock, flags);
+
+	switch (state) {
+	case DWC3_LINK_STATE_U0:
+		seq_printf(s, "U0\n");
+		break;
+	case DWC3_LINK_STATE_U1:
+		seq_printf(s, "U1\n");
+		break;
+	case DWC3_LINK_STATE_U2:
+		seq_printf(s, "U2\n");
+		break;
+	case DWC3_LINK_STATE_U3:
+		seq_printf(s, "U3\n");
+		break;
+	case DWC3_LINK_STATE_SS_DIS:
+		seq_printf(s, "SS.Disabled\n");
+		break;
+	case DWC3_LINK_STATE_RX_DET:
+		seq_printf(s, "Rx.Detect\n");
+		break;
+	case DWC3_LINK_STATE_SS_INACT:
+		seq_printf(s, "SS.Inactive\n");
+		break;
+	case DWC3_LINK_STATE_POLL:
+		seq_printf(s, "Poll\n");
+		break;
+	case DWC3_LINK_STATE_RECOV:
+		seq_printf(s, "Recovery\n");
+		break;
+	case DWC3_LINK_STATE_HRESET:
+		seq_printf(s, "HRESET\n");
+		break;
+	case DWC3_LINK_STATE_CMPLY:
+		seq_printf(s, "Compliance\n");
+		break;
+	case DWC3_LINK_STATE_LPBK:
+		seq_printf(s, "Loopback\n");
+		break;
+	default:
+		seq_printf(s, "UNKNOWN %d\n", reg);
+	}
+
+	return 0;
+}
+
+static int dwc3_link_state_open(struct inode *inode, struct file *file)
+{
+	return single_open(file, dwc3_link_state_show, inode->i_private);
+}
+
+static ssize_t dwc3_link_state_write(struct file *file,
+		const char __user *ubuf, size_t count, loff_t *ppos)
+{
+	struct seq_file		*s = file->private_data;
+	struct dwc3		*dwc = s->private;
+	unsigned long		flags;
+	enum dwc3_link_state	state = 0;
+	char			buf[32];
+
+	if (copy_from_user(&buf, ubuf, min_t(size_t, sizeof(buf) - 1, count)))
+		return -EFAULT;
+
+	if (!strncmp(buf, "SS.Disabled", 11))
+		state = DWC3_LINK_STATE_SS_DIS;
+	else if (!strncmp(buf, "Rx.Detect", 9))
+		state = DWC3_LINK_STATE_RX_DET;
+	else if (!strncmp(buf, "SS.Inactive", 11))
+		state = DWC3_LINK_STATE_SS_INACT;
+	else if (!strncmp(buf, "Recovery", 8))
+		state = DWC3_LINK_STATE_RECOV;
+	else if (!strncmp(buf, "Compliance", 10))
+		state = DWC3_LINK_STATE_CMPLY;
+	else if (!strncmp(buf, "Loopback", 8))
+		state = DWC3_LINK_STATE_LPBK;
+	else
+		return -EINVAL;
+
+	spin_lock_irqsave(&dwc->lock, flags);
+	dwc3_gadget_set_link_state(dwc, state);
+	spin_unlock_irqrestore(&dwc->lock, flags);
+
+	return count;
+}
+
+static const struct file_operations dwc3_link_state_fops = {
+	.open			= dwc3_link_state_open,
+	.write			= dwc3_link_state_write,
+	.read			= seq_read,
+	.llseek			= seq_lseek,
+	.release		= single_release,
+};
+
 int __devinit dwc3_debugfs_init(struct dwc3 *dwc)
 {
 	struct dentry		*root;
@@ -584,6 +687,13 @@ int __devinit dwc3_debugfs_init(struct dwc3 *dwc)
 		goto err1;
 	}
 
+	file = debugfs_create_file("link_state", S_IRUGO | S_IWUSR, root,
+			dwc, &dwc3_link_state_fops);
+	if (IS_ERR(file)) {
+		ret = PTR_ERR(file);
+		goto err1;
+	}
+
 	return 0;
 
 err1:

drivers/usb/dwc3/gadget.c

@@ -117,7 +117,7 @@ int dwc3_gadget_set_link_state(struct dwc3 *dwc, enum dwc3_link_state state)
 		if (DWC3_DSTS_USBLNKST(reg) == state)
 			return 0;
 
-		usleep_range(500, 1500);
+		udelay(500);
 	}
 
 	dev_vdbg(dwc->dev, "link state change request timed out\n");