[PATCH 11/14 v1] usb: typec: tcpci_maxim: Add support for Sink FRS

[Badhri Jagan Sridharan]

Upon receiving ALERT_EXTENDED.TCPC_SINK_FAST_ROLE_SWAP signal
tcpm to start Sink fast role swap signal.

Inform when TCPM is sourcing vbus.

Signed-off-by: Badhri Jagan Sridharan <bad...@google.com>
---
 drivers/usb/typec/tcpm/tcpci_maxim.c | 50 +++++++++++++++++++++++++---
 1 file changed, 46 insertions(+), 4 deletions(-)

diff --git a/drivers/usb/typec/tcpm/tcpci_maxim.c 
b/drivers/usb/typec/tcpm/tcpci_maxim.c
index b61f290a8f96..6ba808ad901a 100644
--- a/drivers/usb/typec/tcpm/tcpci_maxim.c
+++ b/drivers/usb/typec/tcpm/tcpci_maxim.c
@@ -106,13 +106,22 @@ static void max_tcpci_init_regs(struct max_tcpci_chip 
*chip)
                return;
        }
 
+       ret = max_tcpci_write8(chip, TCPC_ALERT_EXTENDED, 0xff);
+       if (ret < 0) {
+               dev_err(chip->dev, "Unable to clear TCPC_ALERT_EXTENDED 
ret:%d\n", ret);
+               return;
+       }
+
        alert_mask = TCPC_ALERT_TX_SUCCESS | TCPC_ALERT_TX_DISCARDED | 
TCPC_ALERT_TX_FAILED |
                TCPC_ALERT_RX_HARD_RST | TCPC_ALERT_RX_STATUS | 
TCPC_ALERT_CC_STATUS |
-               TCPC_ALERT_VBUS_DISCNCT | TCPC_ALERT_RX_BUF_OVF | 
TCPC_ALERT_POWER_STATUS;
+               TCPC_ALERT_VBUS_DISCNCT | TCPC_ALERT_RX_BUF_OVF | 
TCPC_ALERT_POWER_STATUS |
+               /* Enable Extended alert for detecting Fast Role Swap Signal */
+               TCPC_ALERT_EXTND;
 
        ret = max_tcpci_write16(chip, TCPC_ALERT_MASK, alert_mask);
        if (ret < 0) {
-               dev_err(chip->dev, "Error writing to TCPC_ALERT_MASK ret:%d\n", 
ret);
+               dev_err(chip->dev,
+                       "Error enabling TCPC_ALERT: TCPC_ALERT_MASK write 
failed ret:%d\n", ret);
                return;
        }
 
@@ -122,6 +131,10 @@ static void max_tcpci_init_regs(struct max_tcpci_chip 
*chip)
                dev_err(chip->dev, "Error writing to TCPC_POWER_CTRL ret:%d\n", 
ret);
                return;
        }
+
+       ret = max_tcpci_write8(chip, TCPC_ALERT_EXTENDED_MASK, 
TCPC_SINK_FAST_ROLE_SWAP);
+       if (ret < 0)
+               return;
 }
 
 static void process_rx(struct max_tcpci_chip *chip, u16 status)
@@ -225,10 +238,23 @@ static void process_power_status(struct max_tcpci_chip 
*chip)
        if (ret < 0)
                return;
 
-       if (pwr_status == 0xff)
+       if (pwr_status == 0xff) {
                max_tcpci_init_regs(chip);
-       else
+       } else if (pwr_status & TCPC_POWER_STATUS_SOURCING_VBUS) {
+               tcpm_sourcing_vbus(chip->port);
+               /*
+                * Alawys re-enable boost here.
+                * In normal case, when say an headset is attached, TCPM would
+                * have instructed to TCPC to enable boost, so the call is a
+                * no-op.
+                * But for Fast Role Swap case, Boost turns on autonomously 
without
+                * AP intervention, but, needs AP to enable source mode 
explicitly
+                * for AP to regain control.
+                */
+               max_tcpci_set_vbus(chip->tcpci, &chip->data, true, false);
+       } else {
                tcpm_vbus_change(chip->port);
+       }
 }
 
 static void process_tx(struct max_tcpci_chip *chip, u16 status)
@@ -249,6 +275,7 @@ static irqreturn_t _max_tcpci_irq(struct max_tcpci_chip 
*chip, u16 status)
 {
        u16 mask;
        int ret;
+       u8 reg_status;
 
        /*
         * Clear alert status for everything except RX_STATUS, which shouldn't
@@ -274,6 +301,21 @@ static irqreturn_t _max_tcpci_irq(struct max_tcpci_chip 
*chip, u16 status)
                }
        }
 
+       if (status & TCPC_ALERT_EXTND) {
+               ret = max_tcpci_read8(chip, TCPC_ALERT_EXTENDED, &reg_status);
+               if (ret < 0)
+                       return ret;
+
+               ret = max_tcpci_write8(chip, TCPC_ALERT_EXTENDED, reg_status);
+               if (ret < 0)
+                       return ret;
+
+               if (reg_status & TCPC_SINK_FAST_ROLE_SWAP) {
+                       dev_info(chip->dev, "FRS Signal");
+                       tcpm_sink_frs(chip->port);
+               }
+       }
+
        if (status & TCPC_ALERT_RX_STATUS)
                process_rx(chip, status);
 
-- 
2.28.0.297.g1956fa8f8d-goog