Re: [PATCH v6 11/14] usb: typec: tcpci_maxim: Add support for Sink FRS

[Heikki Krogerus <heikki.krogerus@linux.intel.com>]

On Mon, Aug 31, 2020 at 07:59:24PM -0700, Badhri Jagan Sridharan wrote:
> 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 <badhri@google.com>

Reviewed-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>

> ---
> Changes since v1:
> - Changing patch version to v6 to fix version number confusion.
> ---
>  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);
>  
> -- 
> 2.28.0.402.g5ffc5be6b7-goog

-- 
heikki