linux-kernel - Re: [PATCH v2 3/3] power: wm831x_power: Support USB charger current limit management

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Date:   Mon, 3 Jul 2017 17:50:34 +0200
From:   Sebastian Reichel <sebastian.reichel@...labora.co.uk>
To:     Baolin Wang <baolin.wang@...aro.org>
Cc:     balbi@...nel.org, gregkh@...uxfoundation.org, jun.li@....com,
        peter.chen@...escale.com, broonie@...nel.org,
        john.stultz@...aro.org, neilb@...e.com,
        patches@...nsource.wolfsonmicro.com, linux-pm@...r.kernel.org,
        linux-usb@...r.kernel.org,
        device-mainlining@...ts.linuxfoundation.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 3/3] power: wm831x_power: Support USB charger current
 limit management

Hi,

On Mon, Jul 03, 2017 at 02:07:15PM +0800, Baolin Wang wrote:
> Integrate with the newly added USB charger interface to limit the current
> we draw from the USB input based on the input device configuration
> identified by the USB stack, allowing us to charge more quickly from high
> current inputs without drawing more current than specified from others.
> 
> Signed-off-by: Mark Brown <broonie@...nel.org>
> Signed-off-by: Baolin Wang <baolin.wang@...aro.org>

Missing DT binding documentation, otherwise fine with me.
Would be nice to convert existing drivers:

$ git grep -l extcon -- drivers/power/supply
drivers/power/supply/axp288_charger.c
drivers/power/supply/bq24190_charger.c
drivers/power/supply/charger-manager.c
drivers/power/supply/qcom_smbb.c

-- Sebastian

> ---
>  drivers/power/supply/wm831x_power.c |   61 +++++++++++++++++++++++++++++++++++
>  1 file changed, 61 insertions(+)
> 
> diff --git a/drivers/power/supply/wm831x_power.c b/drivers/power/supply/wm831x_power.c
> index 7082301..3e3480708 100644
> --- a/drivers/power/supply/wm831x_power.c
> +++ b/drivers/power/supply/wm831x_power.c
> @@ -13,6 +13,7 @@
>  #include <linux/platform_device.h>
>  #include <linux/power_supply.h>
>  #include <linux/slab.h>
> +#include <linux/usb/phy.h>
>  
>  #include <linux/mfd/wm831x/core.h>
>  #include <linux/mfd/wm831x/auxadc.h>
> @@ -31,6 +32,8 @@ struct wm831x_power {
>  	char usb_name[20];
>  	char battery_name[20];
>  	bool have_battery;
> +	struct usb_phy *usb_phy;
> +	struct notifier_block usb_notify;
>  };
>  
>  static int wm831x_power_check_online(struct wm831x *wm831x, int supply,
> @@ -125,6 +128,43 @@ static int wm831x_usb_get_prop(struct power_supply *psy,
>  	POWER_SUPPLY_PROP_VOLTAGE_NOW,
>  };
>  
> +/* In milliamps */
> +static const unsigned int wm831x_usb_limits[] = {
> +	0,
> +	2,
> +	100,
> +	500,
> +	900,
> +	1500,
> +	1800,
> +	550,
> +};
> +
> +static int wm831x_usb_limit_change(struct notifier_block *nb,
> +				   unsigned long limit, void *data)
> +{
> +	struct wm831x_power *wm831x_power = container_of(nb,
> +							 struct wm831x_power,
> +							 usb_notify);
> +	unsigned int i, best;
> +
> +	/* Find the highest supported limit */
> +	best = 0;
> +	for (i = 0; i < ARRAY_SIZE(wm831x_usb_limits); i++) {
> +		if (limit >= wm831x_usb_limits[i] &&
> +		    wm831x_usb_limits[best] < wm831x_usb_limits[i])
> +			best = i;
> +	}
> +
> +	dev_dbg(wm831x_power->wm831x->dev,
> +		"Limiting USB current to %umA", wm831x_usb_limits[best]);
> +
> +	wm831x_set_bits(wm831x_power->wm831x, WM831X_POWER_STATE,
> +		        WM831X_USB_ILIM_MASK, best);
> +
> +	return 0;
> +}
> +
>  /*********************************************************************
>   *		Battery properties
>   *********************************************************************/
> @@ -607,6 +647,22 @@ static int wm831x_power_probe(struct platform_device *pdev)
>  		}
>  	}
>  
> +	power->usb_phy = devm_usb_get_phy_by_phandle(&pdev->dev,
> +						     "usb-phy", 0);
> +	if (IS_ERR(power->usb_phy)) {
> +		ret = PTR_ERR(power->usb_phy);
> +		dev_err(&pdev->dev, "Failed to find USB phy: %d\n", ret);
> +		goto err_bat_irq;
> +	}
> +
> +	power->usb_notify.notifier_call = wm831x_usb_limit_change;
> +	ret = usb_register_notifier(power->usb_phy,
> +				    &power->usb_notify);
> +	if (ret) {
> +		dev_err(&pdev->dev, "Failed to register notifier: %d\n", ret);
> +		goto err_bat_irq;
> +	}
> +
>  	return ret;
>  
>  err_bat_irq:
> @@ -637,6 +693,11 @@ static int wm831x_power_remove(struct platform_device *pdev)
>  	struct wm831x *wm831x = wm831x_power->wm831x;
>  	int irq, i;
>  
> +	if (wm831x_power->usb_phy) {
> +		usb_unregister_notifier(wm831x_power->usb_phy,
> +					&wm831x_power->usb_notify);
> +	}
> +
>  	for (i = 0; i < ARRAY_SIZE(wm831x_bat_irqs); i++) {
>  		irq = wm831x_irq(wm831x, 
>  				 platform_get_irq_byname(pdev,
> -- 
> 1.7.9.5
> 

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