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

[Peter Chen <peter.chen@freescale.com>]

On Fri, Aug 14, 2015 at 05:47:46PM +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@kernel.org>
> Signed-off-by: Baolin Wang <baolin.wang@linaro.org>
> ---
>  drivers/power/wm831x_power.c     |   69 ++++++++++++++++++++++++++++++++++++++
>  include/linux/mfd/wm831x/pdata.h |    3 ++
>  2 files changed, 72 insertions(+)
> 
> diff --git a/drivers/power/wm831x_power.c b/drivers/power/wm831x_power.c
> index db11ae6..72c661f 100644
> --- a/drivers/power/wm831x_power.c
> +++ b/drivers/power/wm831x_power.c
> @@ -13,6 +13,7 @@
>  #include <linux/platform_device.h>
>  #include <linux/power_supply.h>
>  #include <linux/slab.h>
> +#include <linux/usb/usb_charger.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_charger *usb_charger;
> +	struct notifier_block usb_notify;
>  };
>  
>  static int wm831x_power_check_online(struct wm831x *wm831x, int supply,
> @@ -125,6 +128,43 @@ static enum power_supply_property wm831x_usb_props[] = {
>  	POWER_SUPPLY_PROP_VOLTAGE_NOW,
>  };
>  
> +/* In miliamps */
> +static unsigned int wm831x_usb_limits[] = {
> +	0,
> +	2,
> +	100,
> +	500,
> +	900,
> +	1500,
> +	1800,
> +	550,
> +};

Why 550 is the last, but not 1800?

> +
> +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);
> +	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 %dmA", wm831x_usb_limits[best]);
> +
> +	wm831x_set_bits(wm831x_power->wm831x, WM831X_POWER_STATE,
> +		        WM831X_USB_ILIM_MASK, best);
> +
> +	return 0;
> +}
> +
>  /*********************************************************************
>   *		Battery properties
>   *********************************************************************/
> @@ -606,8 +646,31 @@ static int wm831x_power_probe(struct platform_device *pdev)
>  		}
>  	}
>  
> +	if (wm831x_pdata && wm831x_pdata->usb_gadget) {

Where the wm831x_pdata->usb_gadget is initialized?

> +		power->usb_charger =
> +			usb_charger_find_by_name(wm831x_pdata->usb_gadget);
> +		if (IS_ERR(power->usb_charger)) {
> +			ret = PTR_ERR(power->usb_charger);
> +			dev_err(&pdev->dev,
> +				"Failed to find USB gadget: %d\n", ret);
> +			goto err_bat_irq;
> +		}
> +
> +		power->usb_notify.notifier_call = wm831x_usb_limit_change;
> +
> +		ret = usb_charger_register_notify(power->usb_charger,
> +						  &power->usb_notify);
> +		if (ret != 0) {
> +			dev_err(&pdev->dev,
> +				"Failed to register notifier: %d\n", ret);
> +			goto err_usb_charger;
> +		}
> +	}
> +
>  	return ret;
>  
> +err_usb_charger:
> +	usb_charger_put(power->usb_charger);
>  err_bat_irq:
>  	--i;
>  	for (; i >= 0; i--) {
> @@ -637,6 +700,12 @@ static int wm831x_power_remove(struct platform_device *pdev)
>  	struct wm831x *wm831x = wm831x_power->wm831x;
>  	int irq, i;
>  
> +	if (wm831x_power->usb_charger) {
> +		usb_charger_unregister_notify(wm831x_power->usb_charger,
> +					      &wm831x_power->usb_notify);
> +		usb_charger_put(wm831x_power->usb_charger);
> +	}
> +
>  	for (i = 0; i < ARRAY_SIZE(wm831x_bat_irqs); i++) {
>  		irq = wm831x_irq(wm831x, 
>  				 platform_get_irq_byname(pdev,
> diff --git a/include/linux/mfd/wm831x/pdata.h b/include/linux/mfd/wm831x/pdata.h
> index dcc9631..5af8399 100644
> --- a/include/linux/mfd/wm831x/pdata.h
> +++ b/include/linux/mfd/wm831x/pdata.h
> @@ -126,6 +126,9 @@ struct wm831x_pdata {
>  	/** The driver should initiate a power off sequence during shutdown */
>  	bool soft_shutdown;
>  
> +	/** dev_name of USB charger gadget to integrate with */
> +	const char *usb_gadget;
> +
>  	int irq_base;
>  	int gpio_base;
>  	int gpio_defaults[WM831X_GPIO_NUM];
> -- 
> 1.7.9.5
> 

-- 

Best Regards,
Peter Chen