Re: [PATCH 2/2] power/supply: Add generic USB charger driver

[Sebastian Reichel]

Hi Paul,

On Sun, Nov 03, 2019 at 11:08:01PM +0100, Paul Cercueil wrote:
> This simple charger driver uses the USB PHY framework to detect the
> presence of a charger.
> 
> Signed-off-by: Paul Cercueil <paul@xxxxxxxxxxxxxxx>
> ---
>  drivers/power/supply/Kconfig               |   7 ++
>  drivers/power/supply/Makefile              |   1 +
>  drivers/power/supply/generic-usb-charger.c | 140 +++++++++++++++++++++
>  3 files changed, 148 insertions(+)
>  create mode 100644 drivers/power/supply/generic-usb-charger.c
> 
> diff --git a/drivers/power/supply/Kconfig b/drivers/power/supply/Kconfig
> index c84a7b1caeb6..069a91d89a42 100644
> --- a/drivers/power/supply/Kconfig
> +++ b/drivers/power/supply/Kconfig
> @@ -51,6 +51,13 @@ config GENERIC_ADC_BATTERY
>  	  Say Y here to enable support for the generic battery driver
>  	  which uses IIO framework to read adc.
>  
> +config GENERIC_USB_CHARGER
> +	tristate "Generic USB charger"
> +	depends on USB_PHY
> +	help
> +	  Say Y here to enable a generic USB charger driver which uses
> +	  the USB PHY framework to detect the presence of the charger.
> +
>  config MAX8925_POWER
>  	tristate "MAX8925 battery charger support"
>  	depends on MFD_MAX8925
> diff --git a/drivers/power/supply/Makefile b/drivers/power/supply/Makefile
> index 6c7da920ea83..03f9b553bdfc 100644
> --- a/drivers/power/supply/Makefile
> +++ b/drivers/power/supply/Makefile
> @@ -8,6 +8,7 @@ power_supply-$(CONFIG_LEDS_TRIGGERS)	+= power_supply_leds.o
>  obj-$(CONFIG_POWER_SUPPLY)	+= power_supply.o
>  obj-$(CONFIG_POWER_SUPPLY_HWMON) += power_supply_hwmon.o
>  obj-$(CONFIG_GENERIC_ADC_BATTERY)	+= generic-adc-battery.o
> +obj-$(CONFIG_GENERIC_USB_CHARGER)	+= generic-usb-charger.o
>  
>  obj-$(CONFIG_PDA_POWER)		+= pda_power.o
>  obj-$(CONFIG_APM_POWER)		+= apm_power.o
> diff --git a/drivers/power/supply/generic-usb-charger.c b/drivers/power/supply/generic-usb-charger.c
> new file mode 100644
> index 000000000000..d005acfc33c7
> --- /dev/null
> +++ b/drivers/power/supply/generic-usb-charger.c
> @@ -0,0 +1,140 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Simple USB charger driver
> + * Copyright (c) 2019 Paul Cercueil <paul@xxxxxxxxxxxxxxx>
> + */
> +
> +#include <linux/module.h>
> +#include <linux/platform_device.h>
> +#include <linux/power_supply.h>
> +#include <linux/usb/phy.h>

Missing <linux/of.h> for of_match_ptr()

> +
> +struct usb_charger {
> +	struct usb_phy *phy;
> +	struct notifier_block nb;
> +	struct power_supply_desc desc;
> +	struct power_supply *charger;
> +};
> +
> +static enum power_supply_property usb_charger_properties[] = {
> +	POWER_SUPPLY_PROP_ONLINE,
> +};
> +
> +static int usb_charger_get_property(struct power_supply *psy,
> +				    enum power_supply_property psp,
> +				    union power_supply_propval *val)
> +{
> +	struct usb_charger *charger = power_supply_get_drvdata(psy);
> +
> +	switch (psp) {
> +	case POWER_SUPPLY_PROP_ONLINE:
> +		val->intval = charger->phy->chg_state == USB_CHARGER_PRESENT;
> +		break;
> +	default:
> +		return -EINVAL;
> +	}
> +
> +	return 0;
> +}
> +
> +static int usb_charger_event(struct notifier_block *nb,
> +			     unsigned long event, void *d)
> +{
> +	struct usb_charger *charger = container_of(nb, struct usb_charger, nb);
> +
> +	power_supply_changed(charger->charger);
> +
> +	return 0;
> +}
> +
> +static int usb_charger_probe(struct platform_device *pdev)
> +{
> +	struct device *dev = &pdev->dev;
> +	struct power_supply_desc *desc;
> +	struct usb_charger *charger;
> +	struct power_supply_config cfg = {
> +		.of_node = dev->of_node,
> +	};
> +	int err;
> +
> +	charger = devm_kzalloc(dev, sizeof(*charger), GFP_KERNEL);
> +	if (!charger)
> +		return -ENOMEM;
> +
> +	platform_set_drvdata(pdev, charger);
> +	charger->nb.notifier_call = usb_charger_event;
> +	cfg.drv_data = charger;
> +
> +	if (dev->of_node)
> +		charger->phy = devm_usb_get_phy_by_phandle(dev, "phys", 0);
> +	else
> +		charger->phy = devm_usb_get_phy(dev, USB_PHY_TYPE_USB2);
> +	if (IS_ERR(charger->phy)) {
> +		err = PTR_ERR(charger->phy);
> +		if (err != -EPROBE_DEFER)
> +			dev_err(dev, "No transceiver configured");
> +		return err;
> +	}
> +
> +	desc = &charger->desc;
> +	desc->name = "usb-charger";
> +	desc->properties = usb_charger_properties;
> +	desc->num_properties = ARRAY_SIZE(usb_charger_properties);
> +	desc->get_property = usb_charger_get_property;
> +
> +	switch (charger->phy->chg_type) {
> +	case SDP_TYPE:
> +		desc->type = POWER_SUPPLY_TYPE_USB;
> +		break;
> +	case DCP_TYPE:
> +		desc->type = POWER_SUPPLY_TYPE_USB_DCP;
> +		break;
> +	case CDP_TYPE:
> +		desc->type = POWER_SUPPLY_TYPE_USB_CDP;
> +		break;
> +	case ACA_TYPE:
> +		desc->type = POWER_SUPPLY_TYPE_USB_ACA;
> +		break;
> +	default:
> +		desc->type = POWER_SUPPLY_TYPE_UNKNOWN;
> +	}

This is deprecated in favour of the POWER_SUPPLY_PROP_USB_TYPE
property. Set desc->type to POWER_SUPPLY_TYPE_USB and have a
look at e.g. drivers/power/supply/cros_usbpd-charger.c to see
how POWER_SUPPLY_PROP_USB_TYPE is supposed to work.

> +	charger->charger = devm_power_supply_register(dev, desc, &cfg);
> +	if (IS_ERR(charger->charger)) {
> +		dev_err(dev, "Unable to register charger");
> +		return PTR_ERR(charger->charger);
> +	}
> +
> +	return usb_register_notifier(charger->phy, &charger->nb);

Please register with devm_add_action_or_reset() or (better)
create a devm_usb_register_notifier().

> +}
> +
> +static int usb_charger_remove(struct platform_device *pdev)
> +{
> +	struct usb_charger *charger = platform_get_drvdata(pdev);
> +
> +	usb_unregister_notifier(charger->phy, &charger->nb);
> +
> +	return 0;
> +}
> +
> +#ifdef CONFIG_OF
> +static const struct of_device_id usb_charger_of_match[] = {
> +	{ .compatible = "usb-charger" },
> +	{ /* sentinel */ },
> +};
> +MODULE_DEVICE_TABLE(of, usb_charger_of_match);
> +#endif
> +
> +static struct platform_driver usb_charger_driver = {
> +	.driver = {
> +		.name = "usb-charger",
> +		.of_match_table = of_match_ptr(usb_charger_of_match),
> +	},
> +	.probe = usb_charger_probe,
> +	.remove = usb_charger_remove,
> +};
> +module_platform_driver(usb_charger_driver);
> +
> +MODULE_DESCRIPTION("Simple USB charger driver");
> +MODULE_AUTHOR("Paul Cercueil <paul@xxxxxxxxxxxxxxx>");
> +MODULE_LICENSE("GPL");

-- Sebastian

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