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Date:   Thu, 26 Nov 2020 14:35:52 +0200
From:   Heikki Krogerus <heikki.krogerus@...ux.intel.com>
To:     Guido Günther <agx@...xcpu.org>
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v1 1/1] usb: typec: tps6598x: Export some power supply
 properties

On Wed, Nov 25, 2020 at 06:55:46PM +0100, Guido Günther wrote:
> This allows downstream supplies and userspace to detect
> whether external power is supplied.
> 
> Signed-off-by: Guido Günther <agx@...xcpu.org>

This look OK to me, but I have one request below.

Btw. Are you sure that this works when the power supply class is not
enabled? If I remember correctly, there are no stubs for the power
supply functions.

> ---
>  drivers/usb/typec/tps6598x.c | 97 ++++++++++++++++++++++++++++++++++++
>  1 file changed, 97 insertions(+)
> 
> diff --git a/drivers/usb/typec/tps6598x.c b/drivers/usb/typec/tps6598x.c
> index 3db33bb622c3..ea72957602d8 100644
> --- a/drivers/usb/typec/tps6598x.c
> +++ b/drivers/usb/typec/tps6598x.c
> @@ -9,6 +9,7 @@
>  #include <linux/i2c.h>
>  #include <linux/acpi.h>
>  #include <linux/module.h>
> +#include <linux/power_supply.h>
>  #include <linux/regmap.h>
>  #include <linux/interrupt.h>
>  #include <linux/usb/typec.h>
> @@ -55,6 +56,7 @@ enum {
>  };
>  
>  /* TPS_REG_POWER_STATUS bits */
> +#define TPS_POWER_STATUS_CONNECTION	BIT(0)
>  #define TPS_POWER_STATUS_SOURCESINK	BIT(1)
>  #define TPS_POWER_STATUS_PWROPMODE(p)	(((p) & GENMASK(3, 2)) >> 2)
>  
> @@ -96,8 +98,24 @@ struct tps6598x {
>  	struct typec_partner *partner;
>  	struct usb_pd_identity partner_identity;
>  	struct usb_role_switch *role_sw;
> +	struct typec_capability typec_cap;
> +
> +	struct power_supply *psy;
> +	struct power_supply_desc psy_desc;
> +	enum power_supply_usb_type usb_type;
> +};
> +
> +static enum power_supply_property tps6598x_psy_props[] = {
> +	POWER_SUPPLY_PROP_USB_TYPE,
> +	POWER_SUPPLY_PROP_ONLINE,
> +};
> +
> +static enum power_supply_usb_type tps6598x_psy_usb_types[] = {
> +	POWER_SUPPLY_USB_TYPE_C,
>  };
>  
> +static const char *tps6598x_psy_name_prefix = "tps6598x-source-psy-";
> +
>  /*
>   * Max data bytes for Data1, Data2, and other registers. See ch 1.3.2:
>   * https://www.ti.com/lit/ug/slvuan1a/slvuan1a.pdf
> @@ -248,6 +266,8 @@ static int tps6598x_connect(struct tps6598x *tps, u32 status)
>  	if (desc.identity)
>  		typec_partner_set_identity(tps->partner);
>  
> +	power_supply_changed(tps->psy);
> +
>  	return 0;
>  }
>  
> @@ -260,6 +280,7 @@ static void tps6598x_disconnect(struct tps6598x *tps, u32 status)
>  	typec_set_pwr_role(tps->port, TPS_STATUS_PORTROLE(status));
>  	typec_set_vconn_role(tps->port, TPS_STATUS_VCONN(status));
>  	tps6598x_set_data_role(tps, TPS_STATUS_DATAROLE(status), false);
> +	power_supply_changed(tps->psy);
>  }
>  
>  static int tps6598x_exec_cmd(struct tps6598x *tps, const char *cmd,
> @@ -467,6 +488,78 @@ static const struct regmap_config tps6598x_regmap_config = {
>  	.max_register = 0x7F,
>  };
>  
> +static int tps6598x_psy_get_online(struct tps6598x *tps,
> +				   union power_supply_propval *val)
> +{
> +	int ret;
> +	u16 pwr_status;
> +
> +	ret = tps6598x_read16(tps, TPS_REG_POWER_STATUS, &pwr_status);
> +	if (ret < 0)
> +		return ret;
> +
> +	if (!(pwr_status & TPS_POWER_STATUS_CONNECTION) ||
> +	    !(pwr_status & TPS_POWER_STATUS_SOURCESINK)) {
> +		val->intval = 0;
> +	} else {
> +		val->intval = 1;
> +	}
> +	return 0;
> +}
> +
> +static int tps6598x_psy_get_prop(struct power_supply *psy,
> +				 enum power_supply_property psp,
> +				 union power_supply_propval *val)
> +{
> +	struct tps6598x *tps = power_supply_get_drvdata(psy);
> +	int ret = 0;
> +
> +	switch (psp) {
> +	case POWER_SUPPLY_PROP_USB_TYPE:
> +		val->intval = POWER_SUPPLY_USB_TYPE_C;

It shouldn't be a problem to already check if there is PD contract in
place by reading the Power Status register:

        ret = tps6598x_read16(tps, TPS_REG_POWER_STATUS, &pwr_status);
        if (ret < 0)
                ...

        if (TPS_POWER_STATUS_PWROPMODE(pwr_status) == TYPEC_PWR_MODE_PD)
                val->intval = POWER_SUPPLY_USB_TYPE_PD;
        else
                val->intval = POWER_SUPPLY_USB_TYPEC_C;

Something like that.

> +		break;
> +	case POWER_SUPPLY_PROP_ONLINE:
> +		ret = tps6598x_psy_get_online(tps, val);
> +		break;
> +	default:
> +		ret = -EINVAL;
> +		break;
> +	}
> +
> +	return ret;
> +}
> +
> +static int devm_tps6598_psy_register(struct tps6598x *tps)
> +{
> +	struct power_supply_config psy_cfg = {};
> +	const char *port_dev_name = dev_name(tps->dev);
> +	size_t psy_name_len = strlen(tps6598x_psy_name_prefix) +
> +				     strlen(port_dev_name) + 1;
> +	char *psy_name;
> +
> +	psy_cfg.drv_data = tps;
> +	psy_cfg.fwnode = dev_fwnode(tps->dev);
> +	psy_name = devm_kzalloc(tps->dev, psy_name_len, GFP_KERNEL);
> +	if (!psy_name)
> +		return -ENOMEM;
> +
> +	snprintf(psy_name, psy_name_len, "%s%s", tps6598x_psy_name_prefix,
> +		 port_dev_name);
> +	tps->psy_desc.name = psy_name;
> +	tps->psy_desc.type = POWER_SUPPLY_TYPE_USB;
> +	tps->psy_desc.usb_types = tps6598x_psy_usb_types;
> +	tps->psy_desc.num_usb_types = ARRAY_SIZE(tps6598x_psy_usb_types);
> +	tps->psy_desc.properties = tps6598x_psy_props;
> +	tps->psy_desc.num_properties = ARRAY_SIZE(tps6598x_psy_props);
> +	tps->psy_desc.get_property = tps6598x_psy_get_prop;
> +
> +	tps->usb_type = POWER_SUPPLY_USB_TYPE_C;
> +
> +	tps->psy = devm_power_supply_register(tps->dev, &tps->psy_desc,
> +					       &psy_cfg);
> +	return PTR_ERR_OR_ZERO(tps->psy);
> +}
> +
>  static int tps6598x_probe(struct i2c_client *client)
>  {
>  	struct typec_capability typec_cap = { };
> @@ -560,6 +653,10 @@ static int tps6598x_probe(struct i2c_client *client)
>  		goto err_role_put;
>  	}
>  
> +	ret = devm_tps6598_psy_register(tps);
> +	if (ret)
> +		return ret;
> +
>  	tps->port = typec_register_port(&client->dev, &typec_cap);
>  	if (IS_ERR(tps->port)) {
>  		ret = PTR_ERR(tps->port);
> -- 
> 2.29.2

thanks,

-- 
heikki

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