SYV682: Update Driver for B revision silicon

They SYV682B made some meaningful changes to FRS. Update to remove the
workaround put in place for the SYV682A and replace with the FRS logic
for the SYV682B. The RVS alert can now be masked, so remove the message
for an RVS event and repurpose the flag.

There are some other changes, but none require driver changes.

BUG=b:148144711
TEST=Enable FRS in board config, check that FRS works with with a 5V and
20V supply on a fast and slow-discharge FRS device.
BRANCH=none

Signed-off-by: Eric Herrmann <eherrmann@chromium.org>
Change-Id: I78e1c7d5eca593661a7d67346c83775ca990e38d
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/ec/+/2606508
Reviewed-by: Abe Levkoy <alevkoy@chromium.org>
Commit-Queue: Abe Levkoy <alevkoy@chromium.org>

2 files changed, 60 insertions, 69 deletions

diff --git a/driver/ppc/syv682x.c b/driver/ppc/syv682x.c
index 31f6530212..fe1b85b607 100644
--- a/driver/ppc/syv682x.c
+++ b/driver/ppc/syv682x.c
@@ -27,7 +27,7 @@
 #define SYV682X_FLAGS_TSD		BIT(4)
 #define SYV682X_FLAGS_OVP		BIT(5)
 #define SYV682X_FLAGS_5V_OC		BIT(6)
-#define SYV682X_FLAGS_RVS		BIT(7)
+#define SYV682X_FLAGS_FRS		BIT(7)
 #define SYV682X_FLAGS_VCONN_OCP		BIT(8)
 
 static uint32_t irq_pending; /* Bitmask of ports signaling an interrupt. */
@@ -172,8 +172,13 @@ static int syv682x_vbus_source_enable(int port, int enable)
 		 *
 		 * No need to change the voltage path or channel direction. But,
 		 * turn both paths off.
+		 *
+		 * De-assert the FRS GPIO, which will be asserted if we got to
+		 * be a source via an FRS.
 		 */
 		regval |= SYV682X_CONTROL_1_PWR_ENB;
+		if (IS_ENABLED(CONFIG_USB_PD_FRS_PPC))
+			gpio_set_level(ppc_chips[port].frs_en, 0);
 	}
 
 	rv = write_reg(port, SYV682X_CONTROL_1_REG, regval);
@@ -222,25 +227,24 @@ static bool syv682x_interrupt_filter(int port, int regval, int regmask,
  */
 static void syv682x_handle_status_interrupt(int port, int regval)
 {
-	/* An FRS will automatically enable the source path */
-	if (IS_ENABLED(CONFIG_USB_PD_FRS_PPC) &&
-	    (regval & SYV682X_STATUS_FRS)) {
-		atomic_or(&flags[port], SYV682X_FLAGS_SOURCE_ENABLED);
-		atomic_clear_bits(&flags[port], SYV682X_FLAGS_SINK_ENABLED);
-		/*
-		 * Workaround for bug in SYV692.
-		 *
-		 * The SYV682X has an FRS trigger but it is broken in some
-		 * versions of the part. The old parts require VBUS to fall to
-		 * generate the interrupt, it needs to be generated on CC alone.
-		 *
-		 * The workaround is to use to the TCPC trigger if
-		 * available. When the part is fixed, the TCPC trigger is no
-		 * longer needed. If the TCPC doesn't have a trigger, FRS timing
-		 * may be violated for slow-vbus discharge cases.
-		 */
-		if (!IS_ENABLED(CONFIG_USB_PD_FRS_TCPC))
-			pd_got_frs_signal(port);
+	/*
+	 * An FRS will automatically disable sinking immediately, and enable the
+	 * source path if VBUS is <5V. The FRS GPIO must remain asserted until
+	 * VBUS falls below 5V. SYV682X_FLAGS_FRS signals that the SRC state was
+	 * entered via an FRS.
+	 *
+	 * Note the FRS Alert will remain asserted until VBUS has fallen below
+	 * 5V or the frs_en gpio is de-asserted. So use the rising edge trigger.
+	 */
+	if (IS_ENABLED(CONFIG_USB_PD_FRS_PPC)) {
+		if (syv682x_interrupt_filter(port, regval, SYV682X_STATUS_FRS,
+					     SYV682X_FLAGS_FRS)) {
+			atomic_or(&flags[port], SYV682X_FLAGS_SOURCE_ENABLED);
+			atomic_clear_bits(&flags[port],
+					  SYV682X_FLAGS_SINK_ENABLED);
+			if (!IS_ENABLED(CONFIG_USB_PD_FRS_TCPC))
+				pd_got_frs_signal(port);
+		}
 	}
 
 	/*
@@ -305,11 +309,6 @@ static void syv682x_handle_status_interrupt(int port, int regval)
 					  SYV682X_FLAGS_SINK_ENABLED);
 		}
 	}
-
-	if (syv682x_interrupt_filter(port, regval, SYV682X_STATUS_RVS,
-				     SYV682X_FLAGS_RVS)) {
-		ppc_prints("VBUS Reverse Voltage!", port);
-	}
 }
 
 static int syv682x_handle_control_4_interrupt(int port, int regval)
@@ -611,60 +610,44 @@ void syv682x_interrupt(int port)
 #ifdef CONFIG_USB_PD_FRS_PPC
 static int syv682x_set_frs_enable(int port, int enable)
 {
-	int status;
 	int regval;
 
 	read_reg(port, SYV682X_CONTROL_4_REG, &regval);
 	syv682x_handle_control_4_interrupt(port, regval);
 
 	if (enable) {
-		read_reg(port, SYV682X_STATUS_REG, &status);
-		syv682x_handle_status_interrupt(port, status);
 		/*
-		 * Workaround for a bug in SYV682A
-		 *
-		 * The bug is that VBUS needs to be below VBAT when CC is pulled
-		 * low to trigger FRS. This is fine when charging at 5V usually,
-		 * but often not when charging at higher voltages. At higher
-		 * voltages, the CC trigger needs to be disabled for the broken
-		 * parts.
+		 * The CC line is the FRS trigger, and VCONN should
+		 * be ignored. The SYV682 uses the CCx_BPS fields to
+		 * determine if CC1 or CC2 is CC and should be used for
+		 * FRS. This CCx is also connected through to the TCPC.
+		 * The other CCx signal (VCONN) is isolated from the
+		 * TCPC with this write (VCONN must be provided by PPC).
 		 *
-		 * TODO (b/161372139): When this is fixed in SYV682B, always use
-		 * the CC trigger.
+		 * It is not a valid state to have both or neither
+		 * CC_BPS bits set and the CC_FRS enabled, exactly 1
+		 * should be set.
 		 */
-		if (status & SYV682X_STATUS_VSAFE_5V) {
-			/* Inverted register, clear to enable CC detection */
-			regval &= ~SYV682X_CONTROL_4_CC_FRS;
-			/*
-			 * The CC line is the FRS trigger, and VCONN should
-			 * be ignored. The SYV682 uses the CCx_BPS fields to
-			 * determine if CC1 or CC2 is CC and should be used for
-			 * FRS. This CCx is also connected through to the TCPC.
-			 * The other CCx signal (VCONN) is isolated from the
-			 * TCPC with this write (VCONN must be provided by PPC)
-			 *
-			 * It is not a valid state to have both or neither
-			 * CC_BPS bits set and the CC_FRS enabled, exactly 1
-			 * should be set.
-			 */
-			regval &= ~(SYV682X_CONTROL_4_CC1_BPS |
-				    SYV682X_CONTROL_4_CC2_BPS);
-			regval |= flags[port] & SYV682X_FLAGS_CC_POLARITY ?
-					  SYV682X_CONTROL_4_CC2_BPS :
-					  SYV682X_CONTROL_4_CC1_BPS;
-
-		} else {
-			regval |= SYV682X_CONTROL_4_CC_FRS;
-		}
+		regval &= ~(SYV682X_CONTROL_4_CC1_BPS |
+				SYV682X_CONTROL_4_CC2_BPS);
+		regval |= flags[port] & SYV682X_FLAGS_CC_POLARITY ?
+					SYV682X_CONTROL_4_CC2_BPS :
+					SYV682X_CONTROL_4_CC1_BPS;
+		/* set GPIO after configuring */
+		write_reg(port, SYV682X_CONTROL_4_REG, regval);
+		gpio_set_level(ppc_chips[port].frs_en, 1);
 	} else {
 		/*
-		 * Disabling FRS is part of the disconnect sequence, reconnect
-		 * CC lines to TCPC.
+		 * Reconnect CC lines to TCPC. Since the FRS GPIO needs to be
+		 * asserted until VBUS falls below 5V during an FRS, if
+		 * SYV682X_FLAGS_FRS is set then don't deassert it, instead
+		 * disable when sourcing is disabled.
 		 */
 		regval |= SYV682X_CONTROL_4_CC1_BPS | SYV682X_CONTROL_4_CC2_BPS;
+		write_reg(port, SYV682X_CONTROL_4_REG, regval);
+		if (!(flags[port] & SYV682X_FLAGS_FRS))
+			gpio_set_level(ppc_chips[port].frs_en, 0);
 	}
-	write_reg(port, SYV682X_CONTROL_4_REG, regval);
-	gpio_set_level(ppc_chips[port].frs_en, enable);
 	return EC_SUCCESS;
 }
 #endif /*CONFIG_USB_PD_FRS_PPC*/
@@ -721,6 +704,12 @@ static int syv682x_init(int port)
 		return rv;
 	atomic_clear(&sink_ocp_count[port]);
 
+	/*
+	 * Disable FRS prior to configuring the power paths
+	 */
+	if (IS_ENABLED(CONFIG_USB_PD_FRS_PPC))
+		gpio_set_level(ppc_chips[port].frs_en, 0);
+
 	if (!syv682x_is_sink(control_1)
 		|| (status & SYV682X_STATUS_VSAFE_0V)) {
 		/*
@@ -772,8 +761,10 @@ static int syv682x_init(int port)
 	 * Always set the over voltage setting to the maximum to support
 	 * sinking from a 20V PD charger. The common PPC code doesn't provide
 	 * any hooks for indicating what the currently negotiated voltage is.
+	 *
+	 * Mask Alerts due to Reverse Voltage.
 	 */
-	regval = (SYV682X_OVP_23_7 << SYV682X_OVP_BIT_SHIFT);
+	regval = (SYV682X_OVP_23_7 << SYV682X_OVP_BIT_SHIFT) | SYV682X_RVS_MASK;
 	rv = write_reg(port, SYV682X_CONTROL_3_REG, regval);
 	if (rv)
 		return rv;
@@ -781,10 +772,9 @@ static int syv682x_init(int port)
 	/*
 	 * Remove Rd and connect CC1/CC2 lines to TCPC
 	 * Disable Vconn
-	 * Disable CC detection of Fast Role Swap (FRS)
+	 * Enable CC detection of Fast Role Swap (FRS)
 	 */
-	regval = SYV682X_CONTROL_4_CC1_BPS | SYV682X_CONTROL_4_CC2_BPS |
-		 SYV682X_CONTROL_4_CC_FRS;
+	regval = SYV682X_CONTROL_4_CC1_BPS | SYV682X_CONTROL_4_CC2_BPS;
 	rv = write_reg(port, SYV682X_CONTROL_4_REG, regval);
 	if (rv)
 		return rv;
diff --git a/driver/ppc/syv682x.h b/driver/ppc/syv682x.h
index a2458cf17c..0afa56190f 100644
--- a/driver/ppc/syv682x.h
+++ b/driver/ppc/syv682x.h
@@ -71,6 +71,7 @@
 
 /* Control Register 3 */
 #define SYV682X_BUSY			BIT(7)
+#define SYV682X_RVS_MASK		BIT(3)
 #define SYV682X_RST_REG			BIT(0)
 #define SYV682X_OVP_MASK		0x70
 #define SYV682X_OVP_BIT_SHIFT		4