linux-kernel - Re: [PATCH v3 06/11] staging: typec: fusb302: Add support for USB2 charger detection through extcon

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Date:   Wed, 30 Aug 2017 06:58:43 -0700
From:   Guenter Roeck <linux@...ck-us.net>
To:     Hans de Goede <hdegoede@...hat.com>,
        Darren Hart <dvhart@...radead.org>,
        Andy Shevchenko <andy@...radead.org>,
        Wolfram Sang <wsa@...-dreams.de>,
        Sebastian Reichel <sre@...nel.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Heikki Krogerus <heikki.krogerus@...ux.intel.com>
Cc:     platform-driver-x86@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-i2c@...r.kernel.org, Liam Breck <liam@...workimprov.net>,
        Tony Lindgren <tony@...mide.com>, linux-pm@...r.kernel.org,
        devel@...verdev.osuosl.org,
        "Yueyao (Nathan) Zhu" <yueyao@...gle.com>
Subject: Re: [PATCH v3 06/11] staging: typec: fusb302: Add support for USB2
 charger detection through extcon

On 08/30/2017 02:48 AM, Hans de Goede wrote:
> The fusb302 port-controller relies on an external device doing USB2
> charger-type detection.
> 
> The Intel Whiskey Cove PMIC with which the fusb302 is combined on some
> X86/ACPI platforms already has a charger-type detection driver which
> uses extcon to communicate the detected charger-type.
> 
> Rather then inventing a new API for USB2 charger-type detection
> specifically for use with the tcpm code, this commit simply re-uses the
> existing extcon API and uses that do USB2 charger detection.
> 
> Note that the "fcs,extcon-name" property name is only for kernel internal
> use by X86/ACPI platform code and as such is NOT documented in
> the fusb302 devicetree bindings.
> 
> Cc: "Yueyao (Nathan) Zhu" <yueyao@...gle.com>
> Signed-off-by: Hans de Goede <hdegoede@...hat.com>

Reviewed-by: Guenter Roeck <linux@...ck-us.net>

> ---
> Changes in v2:
> -Put extcon code directly in fusb302.c rather then introducing helpers
>   which are only used by fusb302.c
> 
> Changes in v3:
> -Improve commit message
> ---
>   drivers/staging/typec/fusb302/fusb302.c | 49 +++++++++++++++++++++++++++++++++
>   1 file changed, 49 insertions(+)
> 
> diff --git a/drivers/staging/typec/fusb302/fusb302.c b/drivers/staging/typec/fusb302/fusb302.c
> index 675161cf4f3a..6f007f66d597 100644
> --- a/drivers/staging/typec/fusb302/fusb302.c
> +++ b/drivers/staging/typec/fusb302/fusb302.c
> @@ -17,6 +17,7 @@
>   #include <linux/debugfs.h>
>   #include <linux/delay.h>
>   #include <linux/errno.h>
> +#include <linux/extcon.h>
>   #include <linux/gpio.h>
>   #include <linux/i2c.h>
>   #include <linux/interrupt.h>
> @@ -96,6 +97,7 @@ struct fusb302_chip {
>   
>   	int gpio_int_n;
>   	int gpio_int_n_irq;
> +	struct extcon_dev *extcon;
>   
>   	struct workqueue_struct *wq;
>   	struct delayed_work bc_lvl_handler;
> @@ -516,6 +518,38 @@ static int tcpm_get_vbus(struct tcpc_dev *dev)
>   	return ret;
>   }
>   
> +static int tcpm_get_current_limit(struct tcpc_dev *dev)
> +{
> +	struct fusb302_chip *chip = container_of(dev, struct fusb302_chip,
> +						 tcpc_dev);
> +	int current_limit = 0;
> +	unsigned long timeout;
> +
> +	if (!chip->extcon)
> +		return 0;
> +
> +	/*
> +	 * USB2 Charger detection may still be in progress when we get here,
> +	 * this can take upto 600ms, wait 800ms max.
> +	 */
> +	timeout = jiffies + msecs_to_jiffies(800);
> +	do {
> +		if (extcon_get_state(chip->extcon, EXTCON_CHG_USB_SDP) == 1)
> +			current_limit = 500;
> +
> +		if (extcon_get_state(chip->extcon, EXTCON_CHG_USB_CDP) == 1 ||
> +		    extcon_get_state(chip->extcon, EXTCON_CHG_USB_ACA) == 1)
> +			current_limit = 1500;
> +
> +		if (extcon_get_state(chip->extcon, EXTCON_CHG_USB_DCP) == 1)
> +			current_limit = 2000;
> +
> +		msleep(50);
> +	} while (current_limit == 0 && time_before(jiffies, timeout));
> +
> +	return current_limit;
> +}
> +
>   static int fusb302_set_cc_pull(struct fusb302_chip *chip,
>   			       bool pull_up, bool pull_down)
>   {
> @@ -1201,6 +1235,7 @@ static void init_tcpc_dev(struct tcpc_dev *fusb302_tcpc_dev)
>   {
>   	fusb302_tcpc_dev->init = tcpm_init;
>   	fusb302_tcpc_dev->get_vbus = tcpm_get_vbus;
> +	fusb302_tcpc_dev->get_current_limit = tcpm_get_current_limit;
>   	fusb302_tcpc_dev->set_cc = tcpm_set_cc;
>   	fusb302_tcpc_dev->get_cc = tcpm_get_cc;
>   	fusb302_tcpc_dev->set_polarity = tcpm_set_polarity;
> @@ -1685,6 +1720,7 @@ static int fusb302_probe(struct i2c_client *client,
>   	struct fusb302_chip *chip;
>   	struct i2c_adapter *adapter;
>   	struct device *dev = &client->dev;
> +	const char *name;
>   	int ret = 0;
>   	u32 v;
>   
> @@ -1717,6 +1753,19 @@ static int fusb302_probe(struct i2c_client *client,
>   	if (!device_property_read_u32(dev, "fcs,operating-sink-microwatt", &v))
>   		chip->tcpc_config.operating_snk_mw = v / 1000;
>   
> +	/*
> +	 * Devicetree platforms should get extcon via phandle (not yet
> +	 * supported). On ACPI platforms, we get the name from a device prop.
> +	 * This device prop is for kernel internal use only and is expected
> +	 * to be set by the platform code which also registers the i2c client
> +	 * for the fusb302.
> +	 */
> +	if (device_property_read_string(dev, "fcs,extcon-name", &name) == 0) {
> +		chip->extcon = extcon_get_extcon_dev(name);
> +		if (!chip->extcon)
> +			return -EPROBE_DEFER;
> +	}
> +
>   	ret = fusb302_debugfs_init(chip);
>   	if (ret < 0)
>   		return ret;
>