usb: xhci-plat: Add support to modify imod from sysfs

xhci allows interrupts to be moderated at 250ns interval;
provide an sysfs interface to modify interrupt rate from
userspace to understand throughput variation by changing imod.

Usage:
Below command will moderate interrupts at 1ms or (4000 * 250ns)
interval.
echo 4000 > /sys/devices/8a00000.ssusb/8a00000.dwc3/xhci-hcd.0.auto/
config_imod

Change-Id: I455d5a0f9a0314e86f711efd35315002b20f5343
Signed-off-by: Devdutt Patnaik <dpatnaik@codeaurora.org>
Signed-off-by: Azhar Shaikh <azhars@codeaurora.org>
Signed-off-by: Mayank Rana <mrana@codeaurora.org>

1 files changed, 60 insertions, 0 deletions

diff --git a/drivers/usb/host/xhci-plat.c b/drivers/usb/host/xhci-plat.c
index 7c3bdceaf629..197757c20102 100644
--- a/drivers/usb/host/xhci-plat.c
+++ b/drivers/usb/host/xhci-plat.c
@@ -73,6 +73,60 @@ static int xhci_plat_start(struct usb_hcd *hcd)
 	return xhci_run(hcd);
 }
 
+static ssize_t config_imod_store(struct device *pdev,
+		struct device_attribute *attr, const char *buff, size_t size)
+{
+	struct usb_hcd *hcd = dev_get_drvdata(pdev);
+	struct xhci_hcd *xhci;
+	u32 temp;
+	u32 imod;
+	unsigned long flags;
+
+	if (kstrtouint(buff, 10, &imod) != 1)
+		return 0;
+
+	imod &= ER_IRQ_INTERVAL_MASK;
+	xhci = hcd_to_xhci(hcd);
+
+	if (xhci->shared_hcd->state == HC_STATE_SUSPENDED
+		&& hcd->state == HC_STATE_SUSPENDED)
+		return -EACCES;
+
+	spin_lock_irqsave(&xhci->lock, flags);
+	temp = readl_relaxed(&xhci->ir_set->irq_control);
+	temp &= ~ER_IRQ_INTERVAL_MASK;
+	temp |= imod;
+	writel_relaxed(temp, &xhci->ir_set->irq_control);
+	spin_unlock_irqrestore(&xhci->lock, flags);
+
+	return size;
+}
+
+static ssize_t config_imod_show(struct device *pdev,
+		struct device_attribute *attr, char *buff)
+{
+	struct usb_hcd *hcd = dev_get_drvdata(pdev);
+	struct xhci_hcd *xhci;
+	u32 temp;
+	unsigned long flags;
+
+	xhci = hcd_to_xhci(hcd);
+
+	if (xhci->shared_hcd->state == HC_STATE_SUSPENDED
+		&& hcd->state == HC_STATE_SUSPENDED)
+		return -EACCES;
+
+	spin_lock_irqsave(&xhci->lock, flags);
+	temp = readl_relaxed(&xhci->ir_set->irq_control) &
+			ER_IRQ_INTERVAL_MASK;
+	spin_unlock_irqrestore(&xhci->lock, flags);
+
+	return snprintf(buff, PAGE_SIZE, "%08u\n", temp);
+}
+
+static DEVICE_ATTR(config_imod, S_IRUGO | S_IWUSR,
+		config_imod_show, config_imod_store);
+
 static int xhci_plat_probe(struct platform_device *pdev)
 {
 	struct device_node	*node = pdev->dev.of_node;
@@ -191,6 +245,11 @@ static int xhci_plat_probe(struct platform_device *pdev)
 	if (ret)
 		goto dealloc_usb2_hcd;
 
+	ret = device_create_file(&pdev->dev, &dev_attr_config_imod);
+	if (ret)
+		dev_err(&pdev->dev, "%s: unable to create imod sysfs entry\n",
+					__func__);
+	
 	pm_runtime_mark_last_busy(&pdev->dev);
 	pm_runtime_put_autosuspend(&pdev->dev);
 
@@ -224,6 +283,7 @@ static int xhci_plat_remove(struct platform_device *dev)
 
 	pm_runtime_disable(&dev->dev);
 
+	device_remove_file(&dev->dev, &dev_attr_config_imod);
 	usb_remove_hcd(xhci->shared_hcd);
 	usb_phy_shutdown(hcd->usb_phy);