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Subject[PATCH v5 5/9] usb: xhci-pci: Add support for reset controllers
Date
Some atypical users of xhci-pci 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 <nsaenzjulienne@suse.de>
Acked-by: Mathias Nyman <mathias.nyman@linux.intel.com>
Reviewed-by: Philipp Zabel <p.zabel@pengutronix.de>

---

Changes since v3:
- Now that DT is fixed we can use the actual xHCI device to get reset
controller (not altering the reviewed-bys as it wasn't an xHCI/reset
controller issue).

Changes since v2:
- Also reset on resume

Changes since v1:
- Use proper reset API
- Make code simpler

drivers/usb/host/xhci-pci.c | 10 ++++++++++
drivers/usb/host/xhci.h | 2 ++
2 files changed, 12 insertions(+)

diff --git a/drivers/usb/host/xhci-pci.c b/drivers/usb/host/xhci-pci.c
index ef513c2fb843..f8b171825dfc 100644
--- a/drivers/usb/host/xhci-pci.c
+++ b/drivers/usb/host/xhci-pci.c
@@ -12,6 +12,7 @@
#include <linux/slab.h>
#include <linux/module.h>
#include <linux/acpi.h>
+#include <linux/reset.h>

#include "xhci.h"
#include "xhci-trace.h"
@@ -339,6 +340,7 @@ static int xhci_pci_probe(struct pci_dev *dev, const struct pci_device_id *id)
struct xhci_hcd *xhci;
struct usb_hcd *hcd;
struct xhci_driver_data *driver_data;
+ struct reset_control *reset;

driver_data = (struct xhci_driver_data *)id->driver_data;
if (driver_data && driver_data->quirks & XHCI_RENESAS_FW_QUIRK) {
@@ -347,6 +349,11 @@ static int xhci_pci_probe(struct pci_dev *dev, const struct pci_device_id *id)
return retval;
}

+ reset = devm_reset_control_get_optional_exclusive(&dev->dev, NULL);
+ if (IS_ERR(reset))
+ return PTR_ERR(reset);
+ reset_control_reset(reset);
+
/* Prevent runtime suspending between USB-2 and USB-3 initialization */
pm_runtime_get_noresume(&dev->dev);

@@ -364,6 +371,7 @@ static int xhci_pci_probe(struct pci_dev *dev, const struct pci_device_id *id)
/* USB 2.0 roothub is stored in the PCI device now. */
hcd = dev_get_drvdata(&dev->dev);
xhci = hcd_to_xhci(hcd);
+ xhci->reset = reset;
xhci->shared_hcd = usb_create_shared_hcd(&xhci_pci_hc_driver, &dev->dev,
pci_name(dev), hcd);
if (!xhci->shared_hcd) {
@@ -515,6 +523,8 @@ static int xhci_pci_resume(struct usb_hcd *hcd, bool hibernated)
struct pci_dev *pdev = to_pci_dev(hcd->self.controller);
int retval = 0;

+ reset_control_reset(xhci->reset);
+
/* The BIOS on systems with the Intel Panther Point chipset may or may
* not support xHCI natively. That means that during system resume, it
* may switch the ports back to EHCI so that users can use their
diff --git a/drivers/usb/host/xhci.h b/drivers/usb/host/xhci.h
index c295e8a7f5ae..b22840049ff7 100644
--- a/drivers/usb/host/xhci.h
+++ b/drivers/usb/host/xhci.h
@@ -1770,6 +1770,8 @@ struct xhci_hcd {
/* optional clocks */
struct clk *clk;
struct clk *reg_clk;
+ /* optional reset controller */
+ struct reset_control *reset;
/* data structures */
struct xhci_device_context_array *dcbaa;
struct xhci_ring *cmd_ring;
--
2.27.0
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