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Date: Thu, 12 Dec 2019 09:18:17 +0000
From: Peter Chen <peter.chen@....com>
To: Paul Cercueil <paul@...pouillou.net>
CC: Sebastian Reichel <sre@...nel.org>,
Rob Herring <robh+dt@...nel.org>,
Mark Rutland <mark.rutland@....com>,
Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
"od@...c.me" <od@...c.me>,
"linux-pm@...r.kernel.org" <linux-pm@...r.kernel.org>,
"devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
"linux-usb@...r.kernel.org" <linux-usb@...r.kernel.org>
Subject: Re: [PATCH v2 3/3] power/supply: Add generic USB charger driver
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@...pouillou.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@...pouillou.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
> +
> + 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@...pouillou.net>");
> +MODULE_LICENSE("GPL");
> --
> 2.24.0
>
--
Thanks,
Peter Chen
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