usb: host: xhci-plat: add clock support

Some platforms (such as the Armada 38x ones) can gate the clock of
their USB controller. This patch adds the support for one clock in
xhci-plat, by enabling it during probe and disabling it on remove.

To achieve this, it adds a 'struct clk *' member in xhci_hcd. While
only used for now in xhci-plat, it might be used by other drivers in
the future. Moreover, the xhci_hcd structure already holds other
members such as msix_count and msix_entries, which are MSI-X specific,
and therefore only used by xhci-pci.

Signed-off-by: Gregory CLEMENT <gregory.clement@free-electrons.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Acked-by: Felipe Balbi <balbi@ti.com>
Acked-by: Mathias Nyman <mathias.nyman@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 23 insertions, 1 deletions

diff --git a/drivers/usb/host/xhci-plat.c b/drivers/usb/host/xhci-plat.c
index f5351af4b2c5..8108e58c9e02 100644
--- a/drivers/usb/host/xhci-plat.c
+++ b/drivers/usb/host/xhci-plat.c
@@ -11,6 +11,7 @@
  * version 2 as published by the Free Software Foundation.
  */
 
+#include <linux/clk.h>
 #include <linux/dma-mapping.h>
 #include <linux/module.h>
 #include <linux/of.h>
@@ -91,6 +92,7 @@ static int xhci_plat_probe(struct platform_device *pdev)
         struct xhci_hcd         *xhci;
         struct resource         *res;
         struct usb_hcd          *hcd;
+        struct clk              *clk;
         int                     ret;
         int                     irq;
 
@@ -137,14 +139,27 @@ static int xhci_plat_probe(struct platform_device *pdev)
                 goto release_mem_region;
         }
 
+        /*
+         * Not all platforms have a clk so it is not an error if the
+         * clock does not exists.
+         */
+        clk = devm_clk_get(&pdev->dev, NULL);
+        if (!IS_ERR(clk)) {
+                ret = clk_prepare_enable(clk);
+                if (ret)
+                        goto unmap_registers;
+        }
+
         ret = usb_add_hcd(hcd, irq, IRQF_SHARED);
         if (ret)
-                goto unmap_registers;
+                goto disable_clk;
+
         device_wakeup_enable(hcd->self.controller);
 
         /* USB 2.0 roothub is stored in the platform_device now. */
         hcd = platform_get_drvdata(pdev);
         xhci = hcd_to_xhci(hcd);
+        xhci->clk = clk;
         xhci->shared_hcd = usb_create_shared_hcd(driver, &pdev->dev,
                         dev_name(&pdev->dev), hcd);
         if (!xhci->shared_hcd) {
@@ -173,6 +188,10 @@ put_usb3_hcd:
 dealloc_usb2_hcd:
         usb_remove_hcd(hcd);
 
+disable_clk:
+        if (!IS_ERR(clk))
+                clk_disable_unprepare(clk);
+
 unmap_registers:
         iounmap(hcd->regs);
 
@@ -189,11 +208,14 @@ static int xhci_plat_remove(struct platform_device *dev)
 {
         struct usb_hcd  *hcd = platform_get_drvdata(dev);
         struct xhci_hcd *xhci = hcd_to_xhci(hcd);
+        struct clk *clk = xhci->clk;
 
         usb_remove_hcd(xhci->shared_hcd);
         usb_put_hcd(xhci->shared_hcd);
 
         usb_remove_hcd(hcd);
+        if (!IS_ERR(clk))
+                clk_disable_unprepare(clk);
         iounmap(hcd->regs);
         release_mem_region(hcd->rsrc_start, hcd->rsrc_len);
         usb_put_hcd(hcd);