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SubjectRe: [PATCH v3 3/3] power: wm831x_power: Support USB charger current limit management
Hi,

On 25 July 2017 at 17:59, Sebastian Reichel
<sebastian.reichel@collabora.co.uk> wrote:
> Hi,
>
> On Tue, Jul 25, 2017 at 04:00:01PM +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>
>> ---
>> Documentation/devicetree/bindings/mfd/wm831x.txt | 1 +
>> drivers/power/supply/wm831x_power.c | 58 ++++++++++++++++++++++
>> 2 files changed, 59 insertions(+)
>>
>> diff --git a/Documentation/devicetree/bindings/mfd/wm831x.txt b/Documentation/devicetree/bindings/mfd/wm831x.txt
>> index 9f8b743..4e3bc07 100644
>> --- a/Documentation/devicetree/bindings/mfd/wm831x.txt
>> +++ b/Documentation/devicetree/bindings/mfd/wm831x.txt
>> @@ -31,6 +31,7 @@ Required properties:
>> ../interrupt-controller/interrupts.txt
>>
>> Optional sub-nodes:
>> + - usb-phy : Contains a phandle to the USB PHY.
>> - regulators : Contains sub-nodes for each of the regulators supplied by
>> the device. The regulators are bound using their names listed below:
>>
>> diff --git a/drivers/power/supply/wm831x_power.c b/drivers/power/supply/wm831x_power.c
>> index 7082301..d3948ab 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 +647,19 @@ 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)) {
>> + 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;
>> + }
>> + }
>
> No error handling for power->usb_phy? I think you should bail out
> for all errors except for "not defined in DT". Especially I would
> expect probe defer handling in case the power supply driver is
> loaded before the phy driver.

Make sense. So I think I need to change like below:

power->usb_phy = devm_usb_get_phy_by_phandle(&pdev->dev, "usb-phy", 0);
if (!IS_ERR(power->usb_phy)) {
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;
}
} else if (PTR_ERR(power->usb_phy) != -ENODEV &&
PTR_ERR(power->usb_phy) != -EINVAL) {
ret = PTR_ERR(power->usb_phy);
dev_err(&pdev->dev, "Failed to find USB phy: %d\n", ret);
goto err_bat_irq;
}

The return value -EINVAL means the platform device does not have a
device node and -ENODEV means we did not set the 'usb-phy' phandle,
other errors we should bail out including -PROBE_DEFER. Is it OK for
you?

>
>> return ret;
>>
>> err_bat_irq:
>> @@ -637,6 +690,11 @@ static int wm831x_power_remove(struct platform_device *pdev)
>> struct wm831x *wm831x = wm831x_power->wm831x;
>> int irq, i;
>>
>> + if (!IS_ERR(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,
>
> -- Sebastian



--
Baolin.wang
Best Regards

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