[PATCH v1] usb: typec: tcpci: Check ROLE_CONTROL while interpreting CC_STATUS

[Badhri Jagan Sridharan <badhri@google.com>]

While interpreting CC_STATUS, ROLE_CONTROL has to be read to make
sure that CC1/CC2 is not forced presenting Rp/Rd.

From the TCPCI spec:

4.4.5.2 ROLE_CONTROL (Normative):
The TCPM shall write B6 (DRP) = 0b and B3..0 (CC1/CC2) if it wishes
to control the Rp/Rd directly instead of having the TCPC perform
DRP toggling autonomously. When controlling Rp/Rd directly, the
TCPM writes to B3..0 (CC1/CC2) each time it wishes to change the
CC1/CC2 values. This control is used for TCPM-TCPC implementing
Source or Sink only as well as when a connection has been detected
via DRP toggling but the TCPM wishes to attempt Try.Src or Try.Snk.

Table 4-22. CC_STATUS Register Definition:
If (ROLE_CONTROL.CC1 = Rd) or ConnectResult=1)
00b: SNK.Open (Below maximum vRa)
01b: SNK.Default (Above minimum vRd-Connect)
10b: SNK.Power1.5 (Above minimum vRd-Connect) Detects Rp-1.5A
11b: SNK.Power3.0 (Above minimum vRd-Connect) Detects Rp-3.0A

If (ROLE_CONTROL.CC2=Rd) or (ConnectResult=1)
00b: SNK.Open (Below maximum vRa)
01b: SNK.Default (Above minimum vRd-Connect)
10b: SNK.Power1.5 (Above minimum vRd-Connect) Detects Rp 1.5A
11b: SNK.Power3.0 (Above minimum vRd-Connect) Detects Rp 3.0A

Fixes: 74e656d6b0551 ("staging: typec: Type-C Port Controller
Interface driver (tcpci)")
Signed-off-by: Badhri Jagan Sridharan <badhri@google.com>
---
 drivers/usb/typec/tcpm/tcpci.c | 21 ++++++++++++++++++---
 1 file changed, 18 insertions(+), 3 deletions(-)

diff --git a/drivers/usb/typec/tcpm/tcpci.c b/drivers/usb/typec/tcpm/tcpci.c
index a27deb0b5f03..027afd7dfdce 100644
--- a/drivers/usb/typec/tcpm/tcpci.c
+++ b/drivers/usb/typec/tcpm/tcpci.c
@@ -24,6 +24,15 @@
 #define	AUTO_DISCHARGE_PD_HEADROOM_MV		850
 #define	AUTO_DISCHARGE_PPS_HEADROOM_MV		1250
 
+#define tcpc_presenting_cc1_rd(reg) \
+	(!(TCPC_ROLE_CTRL_DRP & (reg)) && \
+	 (((reg) & (TCPC_ROLE_CTRL_CC1_MASK << TCPC_ROLE_CTRL_CC1_SHIFT)) == \
+	  (TCPC_ROLE_CTRL_CC_RD << TCPC_ROLE_CTRL_CC1_SHIFT)))
+#define tcpc_presenting_cc2_rd(reg) \
+	(!(TCPC_ROLE_CTRL_DRP & (reg)) && \
+	 (((reg) & (TCPC_ROLE_CTRL_CC2_MASK << TCPC_ROLE_CTRL_CC2_SHIFT)) == \
+	  (TCPC_ROLE_CTRL_CC_RD << TCPC_ROLE_CTRL_CC2_SHIFT)))
+
 struct tcpci {
 	struct device *dev;
 
@@ -178,19 +187,25 @@ static int tcpci_get_cc(struct tcpc_dev *tcpc,
 			enum typec_cc_status *cc1, enum typec_cc_status *cc2)
 {
 	struct tcpci *tcpci = tcpc_to_tcpci(tcpc);
-	unsigned int reg;
+	unsigned int reg, role_control;
 	int ret;
 
+	ret = regmap_read(tcpci->regmap, TCPC_ROLE_CTRL, &role_control);
+	if (ret < 0)
+		return ret;
+
 	ret = regmap_read(tcpci->regmap, TCPC_CC_STATUS, &reg);
 	if (ret < 0)
 		return ret;
 
 	*cc1 = tcpci_to_typec_cc((reg >> TCPC_CC_STATUS_CC1_SHIFT) &
 				 TCPC_CC_STATUS_CC1_MASK,
-				 reg & TCPC_CC_STATUS_TERM);
+				 reg & TCPC_CC_STATUS_TERM ||
+				 tcpc_presenting_cc1_rd(role_control));
 	*cc2 = tcpci_to_typec_cc((reg >> TCPC_CC_STATUS_CC2_SHIFT) &
 				 TCPC_CC_STATUS_CC2_MASK,
-				 reg & TCPC_CC_STATUS_TERM);
+				 reg & TCPC_CC_STATUS_TERM ||
+				 tcpc_presenting_cc2_rd(role_control));
 
 	return 0;
 }
-- 
2.30.1.766.gb4fecdf3b7-goog