usb: xhci: add USB2 Link power management BESL support

usb 2.0 devices with link power managment (LPM) can describe their idle link
timeouts either in BESL or HIRD format, so far xHCI has only supported HIRD but
later xHCI errata add BESL support as well

BESL timeouts need to inform exit latency changes with an evaluate
context command the same way USB 3.0 link PM code does.
The same xhci_change_max_exit_latency() function is used as with USB3
but code is pulled out from #ifdef CONFIG_PM as USB2.0 BESL LPM
funcionality does not depend on CONFIG_PM.

Signed-off-by: Mathias Nyman <[e-mail]>
Signed-off-by: Sarah Sharp <[e-mail]>

drivers/usb/host/xhci-ext-caps.h

···
 
 /* USB 2.0 xHCI 1.0 hardware LMP capability - section 7.2.2.1.3.2 */
 #define XHCI_HLC               (1 << 19)
+#define XHCI_BLC               (1 << 19)
 
 /* command register values to disable interrupts and halt the HC */
 /* start/stop HC execution - do not write unless HC is halted*/

drivers/usb/host/xhci.c

···
 	return raw_port;
 }
 
+/*
+ * Issue an Evaluate Context command to change the Maximum Exit Latency in the
+ * slot context.  If that succeeds, store the new MEL in the xhci_virt_device.
+ */
+static int xhci_change_max_exit_latency(struct xhci_hcd *xhci,
+			struct usb_device *udev, u16 max_exit_latency)
+{
+	struct xhci_virt_device *virt_dev;
+	struct xhci_command *command;
+	struct xhci_input_control_ctx *ctrl_ctx;
+	struct xhci_slot_ctx *slot_ctx;
+	unsigned long flags;
+	int ret;
+
+	spin_lock_irqsave(&xhci->lock, flags);
+	if (max_exit_latency == xhci->devs[udev->slot_id]->current_mel) {
+		spin_unlock_irqrestore(&xhci->lock, flags);
+		return 0;
+	}
+
+	/* Attempt to issue an Evaluate Context command to change the MEL. */
+	virt_dev = xhci->devs[udev->slot_id];
+	command = xhci->lpm_command;
+	xhci_slot_copy(xhci, command->in_ctx, virt_dev->out_ctx);
+	spin_unlock_irqrestore(&xhci->lock, flags);
+
+	ctrl_ctx = xhci_get_input_control_ctx(xhci, command->in_ctx);
+	ctrl_ctx->add_flags |= cpu_to_le32(SLOT_FLAG);
+	slot_ctx = xhci_get_slot_ctx(xhci, command->in_ctx);
+	slot_ctx->dev_info2 &= cpu_to_le32(~((u32) MAX_EXIT));
+	slot_ctx->dev_info2 |= cpu_to_le32(max_exit_latency);
+
+	xhci_dbg(xhci, "Set up evaluate context for LPM MEL change.\n");
+	xhci_dbg(xhci, "Slot %u Input Context:\n", udev->slot_id);
+	xhci_dbg_ctx(xhci, command->in_ctx, 0);
+
+	/* Issue and wait for the evaluate context command. */
+	ret = xhci_configure_endpoint(xhci, udev, command,
+			true, true);
+	xhci_dbg(xhci, "Slot %u Output Context:\n", udev->slot_id);
+	xhci_dbg_ctx(xhci, virt_dev->out_ctx, 0);
+
+	if (!ret) {
+		spin_lock_irqsave(&xhci->lock, flags);
+		virt_dev->current_mel = max_exit_latency;
+		spin_unlock_irqrestore(&xhci->lock, flags);
+	}
+	return ret;
+}
+
 #ifdef CONFIG_PM_RUNTIME
 
 /* BESL to HIRD Encoding array for USB2 LPM */
···
 		besl = 15;
 
 	return besl;
+}
+
+/* Calculate BESLD, L1 timeout and HIRDM for USB2 PORTHLPMC */
+static int xhci_calculate_usb2_hw_lpm_params(struct usb_device *udev)
+{
+	u32 field;
+	int l1;
+	int besld = 0;
+	int hirdm = 0;
+
+	field = le32_to_cpu(udev->bos->ext_cap->bmAttributes);
+
+	/* xHCI l1 is set in steps of 256us, xHCI 1.0 section 5.4.11.2 */
+	l1 = XHCI_L1_TIMEOUT / 256;
+
+	/* device has preferred BESLD */
+	if (field & USB_BESL_DEEP_VALID) {
+		besld = USB_GET_BESL_DEEP(field);
+		hirdm = 1;
+	}
+
+	return PORT_BESLD(besld) | PORT_L1_TIMEOUT(l1) | PORT_HIRDM(hirdm);
 }
 
 static int xhci_usb2_software_lpm_test(struct usb_hcd *hcd,
···
 {
 	struct xhci_hcd	*xhci = hcd_to_xhci(hcd);
 	__le32 __iomem	**port_array;
-	__le32 __iomem	*pm_addr;
-	u32		temp;
+	__le32 __iomem	*pm_addr, *hlpm_addr;
+	u32		pm_val, hlpm_val, field;
 	unsigned int	port_num;
 	unsigned long	flags;
-	int		hird;
+	int		hird, exit_latency;
+	int		ret;
 
 	if (hcd->speed == HCD_USB3 || !xhci->hw_lpm_support ||
 			!udev->lpm_capable)
···
 	port_array = xhci->usb2_ports;
 	port_num = udev->portnum - 1;
 	pm_addr = port_array[port_num] + PORTPMSC;
-	temp = xhci_readl(xhci, pm_addr);
+	pm_val = xhci_readl(xhci, pm_addr);
+	hlpm_addr = port_array[port_num] + PORTHLPMC;
+	field = le32_to_cpu(udev->bos->ext_cap->bmAttributes);
 
 	xhci_dbg(xhci, "%s port %d USB2 hardware LPM\n",
 			enable ? "enable" : "disable", port_num);
 
-	hird = xhci_calculate_hird_besl(xhci, udev);
-
 	if (enable) {
-		temp &= ~PORT_HIRD_MASK;
-		temp |= PORT_HIRD(hird) | PORT_RWE;
-		xhci_writel(xhci, temp, pm_addr);
-		temp = xhci_readl(xhci, pm_addr);
-		temp |= PORT_HLE;
-		xhci_writel(xhci, temp, pm_addr);
+		/* Host supports BESL timeout instead of HIRD */
+		if (udev->usb2_hw_lpm_besl_capable) {
+			/* if device doesn't have a preferred BESL value use a
+			 * default one which works with mixed HIRD and BESL
+			 * systems. See XHCI_DEFAULT_BESL definition in xhci.h
+			 */
+			if ((field & USB_BESL_SUPPORT) &&
+			    (field & USB_BESL_BASELINE_VALID))
+				hird = USB_GET_BESL_BASELINE(field);
+			else
+				hird = XHCI_DEFAULT_BESL;
+
+			exit_latency = xhci_besl_encoding[hird];
+			spin_unlock_irqrestore(&xhci->lock, flags);
+
+			/* USB 3.0 code dedicate one xhci->lpm_command->in_ctx
+			 * input context for link powermanagement evaluate
+			 * context commands. It is protected by hcd->bandwidth
+			 * mutex and is shared by all devices. We need to set
+			 * the max ext latency in USB 2 BESL LPM as well, so
+			 * use the same mutex and xhci_change_max_exit_latency()
+			 */
+			mutex_lock(hcd->bandwidth_mutex);
+			ret = xhci_change_max_exit_latency(xhci, udev,
+							   exit_latency);
+			mutex_unlock(hcd->bandwidth_mutex);
+
+			if (ret < 0)
+				return ret;
+			spin_lock_irqsave(&xhci->lock, flags);
+
+			hlpm_val = xhci_calculate_usb2_hw_lpm_params(udev);
+			xhci_writel(xhci, hlpm_val, hlpm_addr);
+			/* flush write */
+			xhci_readl(xhci, hlpm_addr);
+		} else {
+			hird = xhci_calculate_hird_besl(xhci, udev);
+		}
+
+		pm_val &= ~PORT_HIRD_MASK;
+		pm_val |= PORT_HIRD(hird) | PORT_RWE;
+		xhci_writel(xhci, pm_val, pm_addr);
+		pm_val = xhci_readl(xhci, pm_addr);
+		pm_val |= PORT_HLE;
+		xhci_writel(xhci, pm_val, pm_addr);
+		/* flush write */
+		xhci_readl(xhci, pm_addr);
 	} else {
-		temp &= ~(PORT_HLE | PORT_RWE | PORT_HIRD_MASK);
-		xhci_writel(xhci, temp, pm_addr);
+		pm_val &= ~(PORT_HLE | PORT_RWE | PORT_HIRD_MASK);
+		xhci_writel(xhci, pm_val, pm_addr);
+		/* flush write */
+		xhci_readl(xhci, pm_addr);
+		if (udev->usb2_hw_lpm_besl_capable) {
+			spin_unlock_irqrestore(&xhci->lock, flags);
+			mutex_lock(hcd->bandwidth_mutex);
+			xhci_change_max_exit_latency(xhci, udev, 0);
+			mutex_unlock(hcd->bandwidth_mutex);
+			return 0;
+		}
 	}
 
 	spin_unlock_irqrestore(&xhci->lock, flags);
···
 		if (xhci->hw_lpm_support == 1 &&
 		    xhci_check_usb2_port_capability(xhci, portnum, XHCI_HLC)) {
 			udev->usb2_hw_lpm_capable = 1;
+			if (xhci_check_usb2_port_capability(xhci, portnum,
+							    XHCI_BLC))
+				udev->usb2_hw_lpm_besl_capable = 1;
 			ret = xhci_set_usb2_hardware_lpm(hcd, udev, 1);
 			if (!ret)
 				udev->usb2_hw_lpm_enabled = 1;
···
 			return timeout;
 	}
 	return timeout;
-}
-
-/*
- * Issue an Evaluate Context command to change the Maximum Exit Latency in the
- * slot context.  If that succeeds, store the new MEL in the xhci_virt_device.
- */
-static int xhci_change_max_exit_latency(struct xhci_hcd *xhci,
-			struct usb_device *udev, u16 max_exit_latency)
-{
-	struct xhci_virt_device *virt_dev;
-	struct xhci_command *command;
-	struct xhci_input_control_ctx *ctrl_ctx;
-	struct xhci_slot_ctx *slot_ctx;
-	unsigned long flags;
-	int ret;
-
-	spin_lock_irqsave(&xhci->lock, flags);
-	if (max_exit_latency == xhci->devs[udev->slot_id]->current_mel) {
-		spin_unlock_irqrestore(&xhci->lock, flags);
-		return 0;
-	}
-
-	/* Attempt to issue an Evaluate Context command to change the MEL. */
-	virt_dev = xhci->devs[udev->slot_id];
-	command = xhci->lpm_command;
-	xhci_slot_copy(xhci, command->in_ctx, virt_dev->out_ctx);
-	spin_unlock_irqrestore(&xhci->lock, flags);
-
-	ctrl_ctx = xhci_get_input_control_ctx(xhci, command->in_ctx);
-	ctrl_ctx->add_flags |= cpu_to_le32(SLOT_FLAG);
-	slot_ctx = xhci_get_slot_ctx(xhci, command->in_ctx);
-	slot_ctx->dev_info2 &= cpu_to_le32(~((u32) MAX_EXIT));
-	slot_ctx->dev_info2 |= cpu_to_le32(max_exit_latency);
-
-	xhci_dbg(xhci, "Set up evaluate context for LPM MEL change.\n");
-	xhci_dbg(xhci, "Slot %u Input Context:\n", udev->slot_id);
-	xhci_dbg_ctx(xhci, command->in_ctx, 0);
-
-	/* Issue and wait for the evaluate context command. */
-	ret = xhci_configure_endpoint(xhci, udev, command,
-			true, true);
-	xhci_dbg(xhci, "Slot %u Output Context:\n", udev->slot_id);
-	xhci_dbg_ctx(xhci, virt_dev->out_ctx, 0);
-
-	if (!ret) {
-		spin_lock_irqsave(&xhci->lock, flags);
-		virt_dev->current_mel = max_exit_latency;
-		spin_unlock_irqrestore(&xhci->lock, flags);
-	}
-	return ret;
 }
 
 static int calculate_max_exit_latency(struct usb_device *udev,

drivers/usb/host/xhci.h

···
 #define	PORT_L1DS(p)		(((p) & 0xff) << 8)
 #define	PORT_HLE		(1 << 16)
 
+
+/* USB2 Protocol PORTHLPMC */
+#define PORT_HIRDM(p)((p) & 3)
+#define PORT_L1_TIMEOUT(p)(((p) & 0xff) << 2)
+#define PORT_BESLD(p)(((p) & 0xf) << 10)
+
+/* use 512 microseconds as USB2 LPM L1 default timeout. */
+#define XHCI_L1_TIMEOUT		512
+
+/* Set default HIRD/BESL value to 4 (350/400us) for USB2 L1 LPM resume latency.
+ * Safe to use with mixed HIRD and BESL systems (host and device) and is used
+ * by other operating systems.
+ *
+ * XHCI 1.0 errata 8/14/12 Table 13 notes:
+ * "Software should choose xHC BESL/BESLD field values that do not violate a
+ * device's resume latency requirements,
+ * e.g. not program values > '4' if BLC = '1' and a HIRD device is attached,
+ * or not program values < '4' if BLC = '0' and a BESL device is attached.
+ */
+#define XHCI_DEFAULT_BESL	4
+
 /**
  * struct xhci_intr_reg - Interrupt Register Set
  * @irq_pending:	IMAN - Interrupt Management Register.  Used to enable

include/linux/usb.h

···
  * @wusb: device is Wireless USB
  * @lpm_capable: device supports LPM
  * @usb2_hw_lpm_capable: device can perform USB2 hardware LPM
+ * @usb2_hw_lpm_besl_capable: device can perform USB2 hardware BESL LPM
  * @usb2_hw_lpm_enabled: USB2 hardware LPM enabled
  * @usb3_lpm_enabled: USB3 hardware LPM enabled
  * @string_langid: language ID for strings
···
 	unsigned wusb:1;
 	unsigned lpm_capable:1;
 	unsigned usb2_hw_lpm_capable:1;
+	unsigned usb2_hw_lpm_besl_capable:1;
 	unsigned usb2_hw_lpm_enabled:1;
 	unsigned usb3_lpm_enabled:1;
 	int string_langid;