[PATCH v6 4/4] usb: xhci: Add reset controller support

[Nicolas Saenz Julienne]

Some atypical users of xhci might need to manually reset their xHCI
controller before starting the HCD setup. Check if a reset controller
device is available to the PCI bus and trigger a reset.

Signed-off-by: Nicolas Saenz Julienne <nsaenzjulie...@suse.de>

---
Changes since v5:
 - Take !CONFIG_IS_ENABLED(DM_RESET) into account

 drivers/usb/host/xhci-mem.c |  2 ++
 drivers/usb/host/xhci.c     | 33 +++++++++++++++++++++++++++++++++
 include/usb/xhci.h          |  2 ++
 3 files changed, 37 insertions(+)

diff --git a/drivers/usb/host/xhci-mem.c b/drivers/usb/host/xhci-mem.c
index f446520528..108f4bd8cf 100644
--- a/drivers/usb/host/xhci-mem.c
+++ b/drivers/usb/host/xhci-mem.c
@@ -180,6 +180,8 @@ void xhci_cleanup(struct xhci_ctrl *ctrl)
        xhci_free_virt_devices(ctrl);
        free(ctrl->erst.entries);
        free(ctrl->dcbaa);
+       if (reset_valid(&ctrl->reset))
+               reset_free(&ctrl->reset);
        memset(ctrl, '\0', sizeof(struct xhci_ctrl));
 }
 
diff --git a/drivers/usb/host/xhci.c b/drivers/usb/host/xhci.c
index ebd2954571..e252964d0d 100644
--- a/drivers/usb/host/xhci.c
+++ b/drivers/usb/host/xhci.c
@@ -190,6 +190,35 @@ static int xhci_start(struct xhci_hcor *hcor)
        return ret;
 }
 
+/**
+ * Resets XHCI Hardware
+ *
+ * @param ctrl pointer to host controller
+ * @return 0 if OK, or a negative error code.
+ */
+static int xhci_reset_hw(struct xhci_ctrl *ctrl)
+{
+       int ret;
+
+       ret = reset_get_by_index(ctrl->dev, 0, &ctrl->reset);
+       if (ret && ret != -ENOENT && ret != -ENOTSUPP) {
+               dev_err(ctrl->dev, "failed to get reset\n");
+               return ret;
+       }
+
+       if (reset_valid(&ctrl->reset)) {
+               ret = reset_assert(&ctrl->reset);
+               if (ret)
+                       return ret;
+
+               ret = reset_deassert(&ctrl->reset);
+               if (ret)
+                       return ret;
+       }
+
+       return 0;
+}
+
 /**
  * Resets the XHCI Controller
  *
@@ -1508,6 +1537,10 @@ int xhci_register(struct udevice *dev, struct xhci_hccr 
*hccr,
 
        ctrl->dev = dev;
 
+       ret = xhci_reset_hw(ctrl);
+       if (ret)
+               goto err;
+
        /*
         * XHCI needs to issue a Address device command to setup
         * proper device context structures, before it can interact
diff --git a/include/usb/xhci.h b/include/usb/xhci.h
index 1170c0ac69..7d34103fd5 100644
--- a/include/usb/xhci.h
+++ b/include/usb/xhci.h
@@ -16,6 +16,7 @@
 #ifndef HOST_XHCI_H_
 #define HOST_XHCI_H_
 
+#include <reset.h>
 #include <asm/types.h>
 #include <asm/cache.h>
 #include <asm/io.h>
@@ -1209,6 +1210,7 @@ struct xhci_ctrl {
 #if CONFIG_IS_ENABLED(DM_USB)
        struct udevice *dev;
 #endif
+       struct reset_ctl reset;
        struct xhci_hccr *hccr; /* R/O registers, not need for volatile */
        struct xhci_hcor *hcor;
        struct xhci_doorbell_array *dba;
-- 
2.27.0