ANX7451: Add power off and wake up routines

Add anx7451_power_off and anx7451_wake_up routines. ANX7451 is powered
off whenever both USB and DP are disabled. ANX7451 is woken up via i2c
before mux set or get.

BUG=b:184907521
TEST=Mux is powering off when nothing is connected.
     Mux is waking up when cable is connected.
BRANCH=None

Signed-off-by: Rob Barnes <robbarnes@google.com>
Change-Id: Idf1343735cb94eb8bbaebe93794195d2f115b086
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/ec/+/2840056
Reviewed-by: Diana Z <dzigterman@chromium.org>

2 files changed, 56 insertions, 10 deletions

diff --git a/driver/usb_mux/anx7451.c b/driver/usb_mux/anx7451.c
index 38d56e8fcb..c46a78acf8 100644
--- a/driver/usb_mux/anx7451.c
+++ b/driver/usb_mux/anx7451.c
@@ -15,6 +15,13 @@
 #include "usb_mux.h"
 #include "util.h"
 
+/*
+ * Empirical testing found it takes ~12ms to wake mux.
+ * Setting timeout to 20ms for some buffer.
+ */
+#define ANX7451_I2C_WAKE_TIMEOUT_MS 20
+#define ANX7451_I2C_WAKE_RETRY_DELAY_US 500
+
 #define CPRINTS(format, args...) cprints(CC_USBCHARGE, format, ## args)
 #define CPRINTF(format, args...) cprintf(CC_USBCHARGE, format, ## args)
 
@@ -30,6 +37,45 @@ static inline int anx7451_write(const struct usb_mux *me,
 	return i2c_write8(me->i2c_port, me->i2c_addr_flags, reg, val);
 }
 
+static int anx7451_power_off(const struct usb_mux *me)
+{
+	/*
+	 * The mux will not send an acknowledgment when powered off, so ignore
+	 * response and always return success.
+	 */
+	anx7451_write(me, ANX7451_REG_POWER_CNTRL, ANX7451_POWER_CNTRL_OFF);
+	return EC_SUCCESS;
+}
+
+static int anx7451_wake_up(const struct usb_mux *me)
+{
+	timestamp_t start;
+	int rv;
+	int val;
+
+	if (chipset_in_state(CHIPSET_STATE_HARD_OFF))
+		return EC_ERROR_NOT_POWERED;
+
+	/* Keep reading top register until mux wakes up or timesout */
+	start = get_time();
+	do {
+		rv = anx7451_read(me, 0x0, &val);
+		if (!rv)
+			break;
+		usleep(ANX7451_I2C_WAKE_RETRY_DELAY_US);
+	} while (time_since32(start) < ANX7451_I2C_WAKE_TIMEOUT_MS * MSEC);
+	if (rv) {
+		CPRINTS("ANX7451: Failed to wake mux rv:%d", rv);
+		return EC_ERROR_TIMEOUT;
+	}
+
+	/* ULTRA_LOW_POWER must always be disabled (Fig 2-2) */
+	RETURN_ERROR(anx7451_write(me, ANX7451_REG_ULTRA_LOW_POWER,
+				   ANX7451_ULTRA_LOW_POWER_DIS));
+
+	return EC_SUCCESS;
+}
+
 static int anx7451_set_mux(const struct usb_mux *me, mux_state_t mux_state)
 {
 	int reg;
@@ -39,17 +85,11 @@ static int anx7451_set_mux(const struct usb_mux *me, mux_state_t mux_state)
 		return (mux_state == USB_PD_MUX_NONE) ? EC_SUCCESS
 						      : EC_ERROR_NOT_POWERED;
 
-	/* ULTRA_LOW_POWER must always be disabled (Fig 2-2) */
-	RETURN_ERROR(anx7451_write(me, ANX7451_REG_ULTRA_LOW_POWER,
-				   ANX7451_ULTRA_LOW_POWER_DIS));
+	/* To disable both DP and USB the mux must be powered off. */
+	if (!(mux_state & (USB_PD_MUX_USB_ENABLED | USB_PD_MUX_DP_ENABLED)))
+		return anx7451_power_off(me);
 
-
-	/* b/184907521: If both DP and USB disabled, mux will fail */
-	if (!(mux_state & (USB_PD_MUX_USB_ENABLED | USB_PD_MUX_DP_ENABLED))) {
-		CPRINTS("ANX7451 requires USB or DP to be set, "
-			"forcing USB enabled");
-		mux_state |= USB_PD_MUX_USB_ENABLED;
-	}
+	RETURN_ERROR(anx7451_wake_up(me));
 
 	/* ULP_CFG_MODE_EN overrides pin control. Always set it */
 	reg = ANX7451_ULP_CFG_MODE_EN;
@@ -71,6 +111,8 @@ static int anx7451_get_mux(const struct usb_mux *me, mux_state_t *mux_state)
 	if (chipset_in_state(CHIPSET_STATE_HARD_OFF))
 		return USB_PD_MUX_NONE;
 
+	RETURN_ERROR(anx7451_wake_up(me));
+
 	*mux_state = 0;
 	RETURN_ERROR(anx7451_read(me, ANX7451_REG_ULP_CFG_MODE, &reg));
 
diff --git a/driver/usb_mux/anx7451.h b/driver/usb_mux/anx7451.h
index c8d302f5c9..cf7a701f6c 100644
--- a/driver/usb_mux/anx7451.h
+++ b/driver/usb_mux/anx7451.h
@@ -15,6 +15,10 @@
 #define ANX7451_I2C_ADDR2_FLAGS		0x16
 #define ANX7451_I2C_ADDR3_FLAGS		0x11
 
+/* This register is not documented in datasheet. */
+#define ANX7451_REG_POWER_CNTRL		0x2B
+#define ANX7451_POWER_CNTRL_OFF		0xFF
+
 /*
  * Ultra low power control register.
  * On ANX7451, this register should always be 0 (disabled).