stm32/usb: Add support for remote wake-up

USB uses a special mode the trigger remote wake-up during host
suspend, by setting the K-state on the data differential pair,
and setting a bit in the USB config descriptor attributes field.

Let's enable that so that hammer can wake up host from S3.

BRANCH=none
BUG=chrome-os-partner:62325
TEST=Connect hammer to chell, put chell in S3. Press a key (or use
     ("kb 3 3 1; kb 3 3 0" in console), or touch trackpad =>
     host wakes.

Change-Id: Ib7b1e9047e01869f07ddd771c9c9bc640eef10d6
Reviewed-on: https://chromium-review.googlesource.com/446240
Commit-Ready: Nicolas Boichat <drinkcat@chromium.org>
Tested-by: Nicolas Boichat <drinkcat@chromium.org>
Reviewed-by: Vincent Palatin <vpalatin@chromium.org>

7 files changed, 63 insertions, 27 deletions

diff --git a/chip/g/usb.c b/chip/g/usb.c
index 0fc4f62242..901a959e92 100644
--- a/chip/g/usb.c
+++ b/chip/g/usb.c
@@ -200,14 +200,6 @@ static void showregs(void)
 #define CONFIG_USB_BCD_DEV 0x0100		/* 1.00 */
 #endif
 
-#ifndef USB_BMATTRIBUTES
-#ifdef CONFIG_USB_SELF_POWERED
-#define USB_BMATTRIBUTES 0xc0  /* Self powered. */
-#else
-#define USB_BMATTRIBUTES 0x80  /* Bus powered. */
-#endif
-#endif
-
 /* USB Standard Device Descriptor */
 static const struct usb_device_descriptor dev_desc = {
 	.bLength = USB_DT_DEVICE_SIZE,
@@ -234,7 +226,14 @@ const struct usb_config_descriptor USB_CONF_DESC(conf) = {
 	.bNumInterfaces = USB_IFACE_COUNT,
 	.bConfigurationValue = 1,		/* Caution: hard-coded value */
 	.iConfiguration = USB_STR_VERSION,
-	.bmAttributes = USB_BMATTRIBUTES, /* bus or self powered */
+	.bmAttributes = 0x80 /* Reserved bit */
+#ifdef CONFIG_USB_SELF_POWERED  /* bus or self powered */
+		      | 0x40
+#endif
+#ifdef CONFIG_USB_REMOTE_WAKEUP
+		      | 0x20
+#endif
+	,
 	.bMaxPower = (CONFIG_USB_MAXPOWER_MA / 2),
 };
 
diff --git a/chip/stm32/usb.c b/chip/stm32/usb.c
index 4cdfe0828c..ad1e76d65b 100644
--- a/chip/stm32/usb.c
+++ b/chip/stm32/usb.c
@@ -36,14 +36,6 @@
 #define CONFIG_USB_BCD_DEV 0x0100 /* 1.00 */
 #endif
 
-#ifndef USB_BMATTRIBUTES
-#ifdef CONFIG_USB_SELF_POWERED
-#define USB_BMATTRIBUTES 0xc0  /* Self powered. */
-#else
-#define USB_BMATTRIBUTES 0x80  /* Bus powered. */
-#endif
-#endif
-
 #ifndef CONFIG_USB_SERIALNO
 #define USB_STR_SERIALNO 0
 #else
@@ -76,7 +68,14 @@ const struct usb_config_descriptor USB_CONF_DESC(conf) = {
 	.bNumInterfaces = USB_IFACE_COUNT,
 	.bConfigurationValue = 1,
 	.iConfiguration = USB_STR_VERSION,
-	.bmAttributes = USB_BMATTRIBUTES, /* bus or self powered */
+	.bmAttributes = 0x80 /* Reserved bit */
+#ifdef CONFIG_USB_SELF_POWERED  /* bus or self powered */
+		      | 0x40
+#endif
+#ifdef CONFIG_USB_REMOTE_WAKEUP
+		      | 0x20
+#endif
+	,
 	.bMaxPower = (CONFIG_USB_MAXPOWER_MA / 2),
 };
 
@@ -332,6 +331,21 @@ static void usb_resume(void)
 	/* USB is in use again */
 	disable_sleep(SLEEP_MASK_USB_DEVICE);
 }
+
+#ifdef CONFIG_USB_REMOTE_WAKEUP
+void usb_wake(void)
+{
+	if (!(STM32_USB_CNTR & STM32_USB_CNTR_FSUSP)) {
+		/* USB is already woken up, nothing to do. */
+		return;
+	}
+
+	/* Set RESUME bit for 1 to 15 ms, then clear it. */
+	STM32_USB_CNTR |= STM32_USB_CNTR_RESUME;
+	msleep(5);
+	STM32_USB_CNTR &= ~STM32_USB_CNTR_RESUME;
+}
+#endif
 #endif /* CONFIG_USB_SUSPEND */
 
 void usb_interrupt(void)
diff --git a/chip/stm32/usb_dwc.c b/chip/stm32/usb_dwc.c
index 1b009a25cf..7ed0c20c60 100644
--- a/chip/stm32/usb_dwc.c
+++ b/chip/stm32/usb_dwc.c
@@ -52,14 +52,6 @@
 #define CONFIG_USB_BCD_DEV 0x0100		/* 1.00 */
 #endif
 
-#ifndef USB_BMATTRIBUTES
-#ifdef CONFIG_USB_SELF_POWERED
-#define USB_BMATTRIBUTES 0xc0  /* Self powered. */
-#else
-#define USB_BMATTRIBUTES 0x80  /* Bus powered. */
-#endif
-#endif
-
 #ifndef CONFIG_USB_SERIALNO
 #define USB_STR_SERIALNO 0
 #else
@@ -93,7 +85,14 @@ const struct usb_config_descriptor USB_CONF_DESC(conf) = {
 	.bNumInterfaces = USB_IFACE_COUNT,
 	.bConfigurationValue = 1,		/* Caution: hard-coded value */
 	.iConfiguration = USB_STR_VERSION,
-	.bmAttributes = USB_BMATTRIBUTES, /* bus or self powered */
+	.bmAttributes = 0x80 /* Reserved bit */
+#ifdef CONFIG_USB_SELF_POWERED  /* bus or self powered */
+		      | 0x40
+#endif
+#ifdef CONFIG_USB_REMOTE_WAKEUP
+		      | 0x20
+#endif
+	,
 	.bMaxPower = (CONFIG_USB_MAXPOWER_MA / 2),
 };
 
diff --git a/chip/stm32/usb_hid_keyboard.c b/chip/stm32/usb_hid_keyboard.c
index 38354815c3..91b8c8ed35 100644
--- a/chip/stm32/usb_hid_keyboard.c
+++ b/chip/stm32/usb_hid_keyboard.c
@@ -165,6 +165,11 @@ static void write_keyboard_report(void)
 		STM32_TOGGLE_EP(USB_EP_HID_KEYBOARD, EP_TX_MASK,
 				EP_TX_VALID, 0);
 	}
+
+#ifdef CONFIG_USB_REMOTE_WAKEUP
+	/* Wake up host, if required. */
+	usb_wake();
+#endif
 }
 
 static void hid_keyboard_tx(void)
diff --git a/chip/stm32/usb_hid_touchpad.c b/chip/stm32/usb_hid_touchpad.c
index a0fc3b311a..92e1b09886 100644
--- a/chip/stm32/usb_hid_touchpad.c
+++ b/chip/stm32/usb_hid_touchpad.c
@@ -327,6 +327,11 @@ void set_touchpad_report(struct usb_hid_touchpad_report *report)
 			 report, sizeof(*report));
 	/* enable TX */
 	STM32_TOGGLE_EP(USB_EP_HID_TOUCHPAD, EP_TX_MASK, EP_TX_VALID, 0);
+
+#ifdef CONFIG_USB_REMOTE_WAKEUP
+	/* Wake up host, if required. */
+	usb_wake();
+#endif
 }
 
 static void hid_touchpad_tx(void)
diff --git a/include/config.h b/include/config.h
index 5811e0f2b5..8577194e8a 100644
--- a/include/config.h
+++ b/include/config.h
@@ -2433,6 +2433,12 @@
  */
 #undef CONFIG_USB_PORT_POWER_SMART_INVERTED
 
+/*
+ * Support waking up host by setting the K-state on the data lines (requires
+ * CONFIG_USB_SUSPEND to be set as well).
+ */
+#undef CONFIG_USB_REMOTE_WAKEUP
+
 /* Support programmable USB device iSerial field. */
 #undef CONFIG_USB_SERIALNO
 
diff --git a/include/usb_api.h b/include/usb_api.h
index c2e365cf28..a251b3f857 100644
--- a/include/usb_api.h
+++ b/include/usb_api.h
@@ -42,6 +42,14 @@ void usb_disconnect(void);
  */
 void usb_release(void);
 
+/*
+ * Tell the host to wake up. Requires CONFIG_USB_REMOTE_WAKEUP to be defined,
+ * and a chip that implements the function.
+ *
+ * This function sleeps, so it must not be used in interrupt context.
+ */
+void usb_wake(void);
+
 #ifdef CONFIG_USB_SELECT_PHY
 /* Select which PHY to use. */
 void usb_select_phy(uint32_t phy);