usb: acpi: add helper to check port lpm capability using acpi _DSM

Add a helper to evaluate ACPI usb device specific method (_DSM) provided
in case the USB3 port shouldn't enter U1 and U2 link states.

This _DSM was added as port specific retimer configuration may lead to
exit latencies growing beyond U1/U2 exit limits, and OS needs a way to
find which ports can't support U1/U2 link power management states.

This _DSM is also used by windows:
Link: https://docs.microsoft.com/en-us/windows-hardware/drivers/bringup/usb-device-specific-method---dsm-
Some patch issues found in testing resolved by Ron Lee

Cc: stable@vger.kernel.org
Tested-by: Ron Lee <ron.lee@intel.com>
Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com>
Link: https://lore.kernel.org/r/20230116142216.1141605-7-mathias.nyman@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/usb/core/usb-acpi.c b/drivers/usb/core/usb-acpi.c
index 6d93428..533baa8 100644 (file)
--- a/drivers/usb/core/usb-acpi.c
+++ b/drivers/usb/core/usb-acpi.c
@@ -37,6 +37,71 @@ bool usb_acpi_power_manageable(struct usb_device *hdev, int index)
 }
 EXPORT_SYMBOL_GPL(usb_acpi_power_manageable);
 
+#define UUID_USB_CONTROLLER_DSM "ce2ee385-00e6-48cb-9f05-2edb927c4899"
+#define USB_DSM_DISABLE_U1_U2_FOR_PORT 5
+
+/**
+ * usb_acpi_port_lpm_incapable - check if lpm should be disabled for a port.
+ * @hdev: USB device belonging to the usb hub
+ * @index: zero based port index
+ *
+ * Some USB3 ports may not support USB3 link power management U1/U2 states
+ * due to different retimer setup. ACPI provides _DSM method which returns 0x01
+ * if U1 and U2 states should be disabled. Evaluate _DSM with:
+ * Arg0: UUID = ce2ee385-00e6-48cb-9f05-2edb927c4899
+ * Arg1: Revision ID = 0
+ * Arg2: Function Index = 5
+ * Arg3: (empty)
+ *
+ * Return 1 if USB3 port is LPM incapable, negative on error, otherwise 0
+ */
+
+int usb_acpi_port_lpm_incapable(struct usb_device *hdev, int index)
+{
+       union acpi_object *obj;
+       acpi_handle port_handle;
+       int port1 = index + 1;
+       guid_t guid;
+       int ret;
+
+       ret = guid_parse(UUID_USB_CONTROLLER_DSM, &guid);
+       if (ret)
+               return ret;
+
+       port_handle = usb_get_hub_port_acpi_handle(hdev, port1);
+       if (!port_handle) {
+               dev_dbg(&hdev->dev, "port-%d no acpi handle\n", port1);
+               return -ENODEV;
+       }
+
+       if (!acpi_check_dsm(port_handle, &guid, 0,
+                           BIT(USB_DSM_DISABLE_U1_U2_FOR_PORT))) {
+               dev_dbg(&hdev->dev, "port-%d no _DSM function %d\n",
+                       port1, USB_DSM_DISABLE_U1_U2_FOR_PORT);
+               return -ENODEV;
+       }
+
+       obj = acpi_evaluate_dsm(port_handle, &guid, 0,
+                               USB_DSM_DISABLE_U1_U2_FOR_PORT, NULL);
+
+       if (!obj)
+               return -ENODEV;
+
+       if (obj->type != ACPI_TYPE_INTEGER) {
+               dev_dbg(&hdev->dev, "evaluate port-%d _DSM failed\n", port1);
+               ACPI_FREE(obj);
+               return -EINVAL;
+       }
+
+       if (obj->integer.value == 0x01)
+               ret = 1;
+
+       ACPI_FREE(obj);
+
+       return ret;
+}
+EXPORT_SYMBOL_GPL(usb_acpi_port_lpm_incapable);
+
 /**
  * usb_acpi_set_power_state - control usb port's power via acpi power
  * resource

diff --git a/include/linux/usb.h b/include/linux/usb.h
index 7d5325d..04a7e94 100644 (file)
--- a/include/linux/usb.h
+++ b/include/linux/usb.h
@@ -774,11 +774,14 @@ extern struct device *usb_intf_get_dma_device(struct usb_interface *intf);
 extern int usb_acpi_set_power_state(struct usb_device *hdev, int index,
        bool enable);
 extern bool usb_acpi_power_manageable(struct usb_device *hdev, int index);
+extern int usb_acpi_port_lpm_incapable(struct usb_device *hdev, int index);
 #else
 static inline int usb_acpi_set_power_state(struct usb_device *hdev, int index,
        bool enable) { return 0; }
 static inline bool usb_acpi_power_manageable(struct usb_device *hdev, int index)
        { return true; }
+static inline int usb_acpi_port_lpm_incapable(struct usb_device *hdev, int index)
+       { return 0; }
 #endif
 
 /* USB autosuspend and autoresume */