[PATCH 0/1] usb: typec: tcpci: read the VBUS_VOLTAGE register

[PATCH 0/1] usb: typec: tcpci: read the VBUS_VOLTAGE register

[Angus Ainslie (Purism)]

I don't have a setup that I can test this code right now.

I did test the tcpci_get_vbus_voltage and on my setup it is always 0.

I don't currently have setup that I can adjust the vbus voltage to
trigger the fault.

Angus Ainslie (Purism) (1):
  usb: typec: tcpci: add functions to read the VBUS voltage

 drivers/usb/typec/tcpm/tcpci.c | 35 ++++++++++++++++++++++++++++++++++
 1 file changed, 35 insertions(+)

-- 
2.17.1

[PATCH 1/1] usb: typec: tcpci: add functions to read the VBUS voltage

[Angus Ainslie (Purism)]

Show an error when the VBUS voltage is out of range.

Signed-off-by: Angus Ainslie (Purism) <angus@akkea.ca>
---
 drivers/usb/typec/tcpm/tcpci.c | 35 ++++++++++++++++++++++++++++++++++
 1 file changed, 35 insertions(+)

diff --git a/drivers/usb/typec/tcpm/tcpci.c b/drivers/usb/typec/tcpm/tcpci.c
index a5746657b190..223941e11ef3 100644
--- a/drivers/usb/typec/tcpm/tcpci.c
+++ b/drivers/usb/typec/tcpm/tcpci.c
@@ -261,6 +261,26 @@ static int tcpci_set_pd_rx(struct tcpc_dev *tcpc, bool enable)
 	return 0;
 }
 
+static int tcpci_get_vbus_voltage(struct tcpc_dev *tcpc)
+{
+	struct tcpci *tcpci = tcpc_to_tcpci(tcpc);
+	u16 vbus_reg;
+	unsigned int vbus_voltage;
+	int ret, scale;
+
+	ret = tcpci_read16(tcpci, TCPC_VBUS_VOLTAGE, &vbus_reg);
+	if (ret < 0)
+		return ret;
+
+	vbus_voltage = vbus_reg & 0x3f;
+
+	scale = (vbus_reg >> 10) & 3;
+	if (scale == 3)
+		return -EIO;
+
+	return (vbus_voltage << scale) * 25;
+}
+
 static int tcpci_get_vbus(struct tcpc_dev *tcpc)
 {
 	struct tcpci *tcpci = tcpc_to_tcpci(tcpc);
@@ -401,6 +421,7 @@ static int tcpci_init(struct tcpc_dev *tcpc)
 irqreturn_t tcpci_irq(struct tcpci *tcpci)
 {
 	u16 status;
+	int ret;
 
 	tcpci_read16(tcpci, TCPC_ALERT, &status);
 
@@ -474,6 +495,20 @@ irqreturn_t tcpci_irq(struct tcpci *tcpci)
 		tcpci_write16(tcpci, TCPC_FAULT_STATUS, fault_status);
 	}
 
+	if (status & (TCPC_ALERT_V_ALARM_LO | TCPC_ALERT_V_ALARM_HI)) {
+		ret = tcpci_get_vbus_voltage(&tcpci->tcpc);
+
+		if (ret >= 0) {
+			if (status & TCPC_ALERT_V_ALARM_LO)
+				dev_err(tcpci->dev, "Low VBUS voltage %d mV\n",
+						ret);
+
+			if (status & TCPC_ALERT_V_ALARM_HI)
+				dev_err(tcpci->dev, "High VBUS voltage %d mV\n",
+						ret);
+		}
+	}
+
 	return IRQ_HANDLED;
 }
 EXPORT_SYMBOL_GPL(tcpci_irq);
-- 
2.17.1

Re: [PATCH 0/1] usb: typec: tcpci: read the VBUS_VOLTAGE register

[Guenter Roeck]

On 5/7/19 5:40 PM, Angus Ainslie (Purism) wrote:
> I don't have a setup that I can test this code right now.
> 
> I did test the tcpci_get_vbus_voltage and on my setup it is always 0.
> 

Odd. PTN5110 is supposed to support it, though the datasheet is a bit vague about it.
It may be disabled. Did you check the status of POWER_CONTROL.VBUS_VOLTAGEMonitor ?

> I don't currently have setup that I can adjust the vbus voltage to
> trigger the fault.
> 
> Angus Ainslie (Purism) (1):
>    usb: typec: tcpci: add functions to read the VBUS voltage
> 
>   drivers/usb/typec/tcpm/tcpci.c | 35 ++++++++++++++++++++++++++++++++++
>   1 file changed, 35 insertions(+)
> 
In general, an introductory patch is only useful if there is more than one patch.

Thanks,
Guenter

Re: [PATCH 1/1] usb: typec: tcpci: add functions to read the VBUS voltage

[Guenter Roeck]

On 5/7/19 5:40 PM, Angus Ainslie (Purism) wrote:
> Show an error when the VBUS voltage is out of range.
> 
> Signed-off-by: Angus Ainslie (Purism) <angus@akkea.ca>
> ---
>   drivers/usb/typec/tcpm/tcpci.c | 35 ++++++++++++++++++++++++++++++++++
>   1 file changed, 35 insertions(+)
> 
> diff --git a/drivers/usb/typec/tcpm/tcpci.c b/drivers/usb/typec/tcpm/tcpci.c
> index a5746657b190..223941e11ef3 100644
> --- a/drivers/usb/typec/tcpm/tcpci.c
> +++ b/drivers/usb/typec/tcpm/tcpci.c
> @@ -261,6 +261,26 @@ static int tcpci_set_pd_rx(struct tcpc_dev *tcpc, bool enable)
>   	return 0;
>   }
>   
> +static int tcpci_get_vbus_voltage(struct tcpc_dev *tcpc)
> +{
> +	struct tcpci *tcpci = tcpc_to_tcpci(tcpc);
> +	u16 vbus_reg;
> +	unsigned int vbus_voltage;
> +	int ret, scale;
> +
> +	ret = tcpci_read16(tcpci, TCPC_VBUS_VOLTAGE, &vbus_reg);
> +	if (ret < 0)
> +		return ret;
> +
> +	vbus_voltage = vbus_reg & 0x3f;
> +
> +	scale = (vbus_reg >> 10) & 3;
> +	if (scale == 3)
> +		return -EIO;
> +
> +	return (vbus_voltage << scale) * 25;
> +}
> +
>   static int tcpci_get_vbus(struct tcpc_dev *tcpc)
>   {
>   	struct tcpci *tcpci = tcpc_to_tcpci(tcpc);
> @@ -401,6 +421,7 @@ static int tcpci_init(struct tcpc_dev *tcpc)
>   irqreturn_t tcpci_irq(struct tcpci *tcpci)
>   {
>   	u16 status;
> +	int ret;
>   
>   	tcpci_read16(tcpci, TCPC_ALERT, &status);
>   
> @@ -474,6 +495,20 @@ irqreturn_t tcpci_irq(struct tcpci *tcpci)
>   		tcpci_write16(tcpci, TCPC_FAULT_STATUS, fault_status);
>   	}
>   
> +	if (status & (TCPC_ALERT_V_ALARM_LO | TCPC_ALERT_V_ALARM_HI)) {
> +		ret = tcpci_get_vbus_voltage(&tcpci->tcpc);
> +
Extra empty line.

> +		if (ret >= 0) {
> +			if (status & TCPC_ALERT_V_ALARM_LO)
> +				dev_err(tcpci->dev, "Low VBUS voltage %d mV\n",
> +						ret);
> +
> +			if (status & TCPC_ALERT_V_ALARM_HI)
> +				dev_err(tcpci->dev, "High VBUS voltage %d mV\n",
> +						ret);
> +		}

This doesn't report anything if reading the VBUS voltage
returns an error.

Also, per TCPCI specification, you probably want to check
POWER_CONTROL.VBUS_VOLTAGE Monitor to see if it is enabled
in the first place.

On a higher level, the driver doesn't currently set limits for low
and high voltage alarms, and it doesn't enable those alarms. As such,
I wonder if/how you can get those alerts. Can you clarify ?

Thanks,
Guenter

> +	}
> +
>   	return IRQ_HANDLED;
>   }
>   EXPORT_SYMBOL_GPL(tcpci_irq);
>