linux-kernel - [PATCH 3/9] usb: dwc2: gadget: Add functionality to exit from LPM L1 state

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Date:   Fri, 28 Apr 2017 12:48:06 +0400
From:   Sevak Arakelyan <SEVAK.ARAKELYAN@...opsys.com>
To:     John Youn <John.Youn@...opsys.com>,
        Felipe Balbi <balbi@...nel.org>,
        "Greg Kroah-Hartman" <gregkh@...uxfoundation.org>,
        <linux-usb@...r.kernel.org>, <linux-kernel@...r.kernel.org>
CC:     Sevak Arakelyan <SEVAK.ARAKELYAN@...opsys.com>
Subject: [PATCH 3/9] usb: dwc2: gadget: Add functionality to exit from LPM L1 state

Add a function which will be called if device is in L1 sleep state
and Resume/Remote Wakeup Detected interrupt is asserted.

Signed-off-by: Sevak Arakelyan <sevaka@...opsys.com>
---
 drivers/usb/dwc2/core_intr.c | 49 ++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 49 insertions(+)

diff --git a/drivers/usb/dwc2/core_intr.c b/drivers/usb/dwc2/core_intr.c
index b8bcb007c92a..c7dd764fbfa9 100644
--- a/drivers/usb/dwc2/core_intr.c
+++ b/drivers/usb/dwc2/core_intr.c
@@ -334,6 +334,50 @@ static void dwc2_handle_session_req_intr(struct dwc2_hsotg *hsotg)
 	}
 }
 
+/**
+ * dwc2_wakeup_from_lpm_l1 - Exit the device from LPM L1 state
+ */
+static void dwc2_wakeup_from_lpm_l1(struct dwc2_hsotg *hsotg)
+{
+	u32 glpmcfg;
+	u32 i = 0;
+
+	if (hsotg->lx_state != DWC2_L1) {
+		dev_err(hsotg->dev, "Core isn't in DWC2_L1 state\n");
+		return;
+	}
+
+	glpmcfg = dwc2_readl(hsotg->regs + GLPMCFG);
+	if (dwc2_is_device_mode(hsotg)) {
+		dev_dbg(hsotg->dev, "Exit from L1 state\n");
+		glpmcfg &= ~GLPMCFG_ENBLSLPM;
+		glpmcfg &= ~GLPMCFG_HIRD_THRES_EN;
+		dwc2_writel(glpmcfg, hsotg->regs + GLPMCFG);
+
+		do {
+			glpmcfg = dwc2_readl(hsotg->regs + GLPMCFG);
+
+			if (!(glpmcfg & (GLPMCFG_COREL1RES_MASK |
+					 GLPMCFG_L1RESUMEOK | GLPMCFG_SLPSTS)))
+				break;
+
+			udelay(1);
+		} while (++i < 200);
+
+		if (i == 200) {
+			dev_err(hsotg->dev, "Failed to exit L1 sleep state in 200us.\n");
+			return;
+		}
+	} else {
+		/* TODO */
+		dev_err(hsotg->dev, "Host side LPM is not supported.\n");
+		return;
+	}
+
+	/* Change to L0 state */
+	hsotg->lx_state = DWC2_L0;
+}
+
 /*
  * This interrupt indicates that the DWC_otg controller has detected a
  * resume or remote wakeup sequence. If the DWC_otg controller is in
@@ -351,6 +395,11 @@ static void dwc2_handle_wakeup_detected_intr(struct dwc2_hsotg *hsotg)
 	dev_dbg(hsotg->dev, "++Resume or Remote Wakeup Detected Interrupt++\n");
 	dev_dbg(hsotg->dev, "%s lxstate = %d\n", __func__, hsotg->lx_state);
 
+	if (hsotg->lx_state == DWC2_L1) {
+		dwc2_wakeup_from_lpm_l1(hsotg);
+		return;
+	}
+
 	if (dwc2_is_device_mode(hsotg)) {
 		dev_dbg(hsotg->dev, "DSTS=0x%0x\n",
 			dwc2_readl(hsotg->regs + DSTS));
-- 
2.11.0