Re: [PATCH v2 3/3] power/supply: Add generic USB charger driver

[Paul Cercueil <paul@crapouillou.net>]

Hi Peter,


Le jeu., déc. 12, 2019 at 09:18, Peter Chen <peter.chen@nxp.com> a 
écrit :
> On 19-12-11 16:50:32, Paul Cercueil wrote:
>>  This simple charger driver uses the USB role switch framework to 
>> detect
>>  the presence of a charger. The USB charger will report as online 
>> when
>>  the USB role is set to device, and offline otherwise.
>> 
>>  Signed-off-by: Paul Cercueil <paul@crapouillou.net>
>>  ---
>> 
>>  Notes:
>>      v2: Instead of detecting charger state from USB PHY, we detect 
>> it from the
>>          USB role in use.
>> 
>>   drivers/power/supply/Kconfig               |   8 ++
>>   drivers/power/supply/Makefile              |   1 +
>>   drivers/power/supply/generic-usb-charger.c | 124 
>> +++++++++++++++++++++
>>   3 files changed, 133 insertions(+)
>>   create mode 100644 drivers/power/supply/generic-usb-charger.c
>> 
>>  diff --git a/drivers/power/supply/Kconfig 
>> b/drivers/power/supply/Kconfig
>>  index 27164a1d3c7c..c4221bcabee4 100644
>>  --- a/drivers/power/supply/Kconfig
>>  +++ b/drivers/power/supply/Kconfig
>>  @@ -51,6 +51,14 @@ 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_SUPPORT
>>  +	select USB_ROLE_SWITCH
>>  +	help
>>  +	  Say Y here to enable a generic USB charger driver which uses
>>  +	  the USB role switch 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..0493fafbd4c0
>>  --- /dev/null
>>  +++ b/drivers/power/supply/generic-usb-charger.c
>>  @@ -0,0 +1,124 @@
>>  +// SPDX-License-Identifier: GPL-2.0
>>  +/*
>>  + * Simple USB charger driver
>>  + * Copyright (c) 2019 Paul Cercueil <paul@crapouillou.net>
>>  + */
>>  +
>>  +#include <linux/device.h>
>>  +#include <linux/module.h>
>>  +#include <linux/of.h>
>>  +#include <linux/platform_device.h>
>>  +#include <linux/power_supply.h>
>>  +#include <linux/usb/role.h>
>>  +
>>  +struct usb_charger {
>>  +	struct notifier_block nb;
>>  +	struct usb_role_switch *role;
>>  +	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);
>>  +	enum usb_role role;
>>  +
>>  +	switch (psp) {
>>  +	case POWER_SUPPLY_PROP_ONLINE:
>>  +		role = usb_role_switch_get_role(charger->role);
>>  +		val->intval = role == USB_ROLE_DEVICE;
>>  +		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 void usb_charger_unregister(void *data)
>>  +{
>>  +	struct usb_charger *charger = data;
>>  +
>>  +	usb_role_switch_unregister_notifier(charger->role, &charger->nb);
>>  +}
>>  +
>>  +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;
>>  +
>>  +	cfg.drv_data = charger;
>>  +	charger->nb.notifier_call = usb_charger_event;
>>  +
>>  +	charger->role = usb_role_switch_get(dev);
>>  +	if (IS_ERR(charger->role)) {
>>  +		if (PTR_ERR(charger->role) != -EPROBE_DEFER)
>>  +			dev_err(dev, "Unable to get USB role");
>>  +		return PTR_ERR(charger->role);
>>  +	}
>>  +
>>  +	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;
>>  +	desc->type = POWER_SUPPLY_TYPE_USB;
> 
> What's your further plan for this generic USB charger?
> To support BC1.2, we need to know charger type, and how
> we could get it?
> 
> Peter

Well I don't really know. The USB role framework does not give any info 
about what's plugged.

-Paul


> 
>>  +
>>  +	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);
>>  +	}
>>  +
>>  +	err = usb_role_switch_register_notifier(charger->role, 
>> &charger->nb);
>>  +	if (err) {
>>  +		dev_err(dev, "Unable to register USB role switch notifier");
>>  +		return err;
>>  +	}
>>  +
>>  +	return devm_add_action_or_reset(dev, usb_charger_unregister, 
>> charger);
>>  +}
>>  +
>>  +static const struct of_device_id usb_charger_of_match[] = {
>>  +	{ .compatible = "usb-charger" },
>>  +	{ /* sentinel */ },
>>  +};
>>  +MODULE_DEVICE_TABLE(of, usb_charger_of_match);
>>  +
>>  +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,
>>  +};
>>  +module_platform_driver(usb_charger_driver);
>>  +
>>  +MODULE_DESCRIPTION("Simple USB charger driver");
>>  +MODULE_AUTHOR("Paul Cercueil <paul@crapouillou.net>");
>>  +MODULE_LICENSE("GPL");
>>  --
>>  2.24.0
>> 
> 
> --
> 
> Thanks,
> Peter Chen