Re: [PATCH 1/4] power: Add an axp20x-ac-power driver

[Maxime Ripard <maxime.ripard-wi1+55ScJUtKEb57/3fJTNBPR1lH4CV8@public.gmane.org>]

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Hi,

On Sun, Apr 03, 2016 at 03:15:04PM +0200, Michael Haas wrote:
> This adds a driver for the ac power_supply bits of the axp20x
> PMICs.
> 
> This submission is taken directly from Bruno Prémonts 2015 RFC [0].
> The original RFC contains drivers for AC, battery and backup
> battery. This commit only adds the AC driver for now.
> 
> My only change to Bruno's axp20x_ac_power.c is the additional
> check on a possible short-circuit between ACIN and VBUS. In this
> case, axp20x-ac-power-supply refuses to attach itself to the device
> and axp20x-usb-power-supply must be used.
> 
> [0] http://permalink.gmane.org/gmane.comp.hardware.netbook.arm.sunxi/17980
> 
> Signed-off-by: Michael Haas <haas-bdq14YP6qtSV9CzYT+GlPGD2FQJk+8+b@public.gmane.org>
> ---
>  drivers/mfd/axp20x.c            |  11 +++
>  drivers/power/Makefile          |   2 +-
>  drivers/power/axp20x_ac_power.c | 212 ++++++++++++++++++++++++++++++++++++++++
>  3 files changed, 224 insertions(+), 1 deletion(-)
>  create mode 100644 drivers/power/axp20x_ac_power.c
> 
> diff --git a/drivers/mfd/axp20x.c b/drivers/mfd/axp20x.c
> index a57d6e9..9351c0e 100644
> --- a/drivers/mfd/axp20x.c
> +++ b/drivers/mfd/axp20x.c
> @@ -178,6 +178,12 @@ static struct resource axp288_power_button_resources[] = {
>  	},
>  };
>  
> +static struct resource axp20x_ac_power_supply_resources[] = {
> +	DEFINE_RES_IRQ_NAMED(AXP20X_IRQ_ACIN_PLUGIN, "ACIN_PLUGIN"),
> +	DEFINE_RES_IRQ_NAMED(AXP20X_IRQ_ACIN_REMOVAL, "ACIN_REMOVAL"),
> +	DEFINE_RES_IRQ_NAMED(AXP20X_IRQ_ACIN_OVER_V, "ACIN_OVER_V"),
> +};
> +
>  static struct resource axp288_fuel_gauge_resources[] = {
>  	{
>  		.start = AXP288_IRQ_QWBTU,
> @@ -440,6 +446,11 @@ static struct mfd_cell axp20x_cells[] = {
>  		.of_compatible	= "x-powers,axp202-usb-power-supply",
>  		.num_resources	= ARRAY_SIZE(axp20x_usb_power_supply_resources),
>  		.resources	= axp20x_usb_power_supply_resources,
> +	}, {
> +		.name		= "axp20x-ac-power-supply",
> +		.of_compatible	= "x-powers,axp202-ac-power-supply",
> +		.num_resources	= ARRAY_SIZE(axp20x_ac_power_supply_resources),
> +		.resources	= axp20x_ac_power_supply_resources,
>  	},
>  };
>

These changes should be in a separate patch.

> diff --git a/drivers/power/Makefile b/drivers/power/Makefile
> index e46b75d..3a785cc 100644
> --- a/drivers/power/Makefile
> +++ b/drivers/power/Makefile
> @@ -9,7 +9,7 @@ obj-$(CONFIG_GENERIC_ADC_BATTERY)	+= generic-adc-battery.o
>  
>  obj-$(CONFIG_PDA_POWER)		+= pda_power.o
>  obj-$(CONFIG_APM_POWER)		+= apm_power.o
> -obj-$(CONFIG_AXP20X_POWER)	+= axp20x_usb_power.o
> +obj-$(CONFIG_AXP20X_POWER)	+= axp20x_usb_power.o axp20x_ac_power.o
>  obj-$(CONFIG_MAX8925_POWER)	+= max8925_power.o
>  obj-$(CONFIG_WM831X_BACKUP)	+= wm831x_backup.o
>  obj-$(CONFIG_WM831X_POWER)	+= wm831x_power.o
> diff --git a/drivers/power/axp20x_ac_power.c b/drivers/power/axp20x_ac_power.c
> new file mode 100644
> index 0000000..c5bcbeb
> --- /dev/null
> +++ b/drivers/power/axp20x_ac_power.c
> @@ -0,0 +1,212 @@
> +/*
> + * AXP20x PMIC AC power driver
> + *
> + * Copyright 2014-2015 Bruno Prémont <bonbons-ud5FBsm0p/xEiooADzr8i9i2O/JbrIOy@public.gmane.org>
> + *
> + * This program is free software; you can redistribute it and/or modify it
> + * under  the terms of the GNU General  Public License as published by the
> + * Free Software Foundation;  either version 2 of the License, or (at your
> + * option) any later version.
> + */
> +
> +#include <linux/err.h>
> +#include <linux/interrupt.h>
> +#include <linux/irq.h>
> +#include <linux/mfd/axp20x.h>
> +#include <linux/module.h>
> +#include <linux/of.h>
> +#include <linux/platform_device.h>
> +#include <linux/power_supply.h>
> +#include <linux/regmap.h>
> +#include <linux/slab.h>
> +
> +#define DRVNAME "axp20x-ac-power"
> +/* Fields of AXP20X_PWR_INPUT_STATUS */
> +#define AXP20X_PWR_STATUS_AC_PRESENT     BIT(7)
> +#define AXP20X_PWR_STATUS_AC_AVAILABLE   BIT(6)
> +#define AXP20X_PWR_STATUS_AC_VBUS_SHORT  BIT(1)
> +#define AXP20X_PWR_STATUS_AC_VBUS_SEL    BIT(0)
> +
> +/* Fields of AXP20X_ADC_EN1 */
> +#define AXP20X_ADC_EN1_ACIN_VOLT BIT(5)
> +#define AXP20X_ADC_EN1_ACIN_CURR BIT(4)

That should probably be defined in the global header, next to the
registers.

> +struct axp20x_ac_power {
> +	struct regmap *regmap;
> +	struct power_supply *supply;
> +};
> +
> +static int axp20x_ac_power_get_property(struct power_supply *psy,
> +	enum power_supply_property psp, union power_supply_propval *val)

The alignment is supposed to be on the opening parentheses

> +{
> +	struct axp20x_ac_power *power = power_supply_get_drvdata(psy);
> +	unsigned int input;
> +	int r;
> +
> +	switch (psp) {
> +	case POWER_SUPPLY_PROP_VOLTAGE_NOW:
> +		r = axp20x_read_variable_width(power->regmap,
> +					       AXP20X_ACIN_V_ADC_H, 12);
> +		if (r < 0)
> +			return r;
> +
> +		val->intval = r * 1700; /* 1 step = 1.7 mV */
> +		return 0;
> +	case POWER_SUPPLY_PROP_CURRENT_NOW:
> +		r = axp20x_read_variable_width(power->regmap,
> +					       AXP20X_ACIN_I_ADC_H, 12);
> +		if (r < 0)
> +			return r;
> +
> +		val->intval = r * 375; /* 1 step = 0.375 mA */
> +		return 0;
> +	default:
> +		break;
> +	}
> +
> +	/* All the properties below need the input-status reg value */
> +	r = regmap_read(power->regmap, AXP20X_PWR_INPUT_STATUS, &input);
> +	if (r)
> +		return r;
> +
> +	switch (psp) {
> +	case POWER_SUPPLY_PROP_PRESENT:
> +		val->intval = !!(input & AXP20X_PWR_STATUS_AC_PRESENT);
> +		break;
> +	case POWER_SUPPLY_PROP_ONLINE:
> +		val->intval = !!(input & AXP20X_PWR_STATUS_AC_AVAILABLE);
> +		break;
> +	default:
> +		return -EINVAL;
> +	}
> +
> +	return 0;
> +}
> +
> +static enum power_supply_property axp20x_ac_power_properties[] = {
> +	POWER_SUPPLY_PROP_PRESENT,
> +	POWER_SUPPLY_PROP_ONLINE,
> +	POWER_SUPPLY_PROP_VOLTAGE_NOW,
> +	POWER_SUPPLY_PROP_CURRENT_NOW,
> +};
> +
> +static const struct power_supply_desc axp20x_ac_power_desc = {
> +	.name = "axp20x-ac",
> +	.type = POWER_SUPPLY_TYPE_MAINS,
> +	.properties = axp20x_ac_power_properties,
> +	.num_properties = ARRAY_SIZE(axp20x_ac_power_properties),
> +	.get_property = axp20x_ac_power_get_property,
> +};
> +
> +static irqreturn_t axp20x_irq_ac_over_v(int irq, void *devid)
> +{
> +	struct axp20x_ac_power *power = devid;
> +
> +	dev_warn(&power->supply->dev, "IRQ#%d AC over voltage\n", irq);
> +	power_supply_changed(power->supply);
> +
> +	return IRQ_HANDLED;
> +}
> +
> +static irqreturn_t axp20x_irq_ac_plugin(int irq, void *devid)
> +{
> +	struct axp20x_ac_power *power = devid;
> +
> +	dev_info(&power->supply->dev, "IRQ#%d AC connected\n", irq);
> +	power_supply_changed(power->supply);
> +
> +	return IRQ_HANDLED;
> +}
> +
> +static irqreturn_t axp20x_irq_ac_removal(int irq, void *devid)
> +{
> +	struct axp20x_ac_power *power = devid;
> +
> +	dev_info(&power->supply->dev, "IRQ#%d AC disconnected\n", irq);
> +	power_supply_changed(power->supply);
> +
> +	return IRQ_HANDLED;
> +}

Logging in the interrupt handler is usually a bad idea, for several
reasons:
   - If you have a console, it's going to be output on the console,
     which might take quite some time. And you don't want to take
     quite some time in the interrupt handler.
   - printk might not even work in the interrupt context in some
     scenarios.

Removing that handler, you can register the same interrupt handler on
all the interrupts.

> +static int axp20x_ac_power_probe(struct platform_device *pdev)
> +{
> +	struct axp20x_dev *axp20x = dev_get_drvdata(pdev->dev.parent);
> +	struct power_supply_config psy_cfg = {};
> +	struct axp20x_ac_power *power;
> +	static const char * const irq_names[] = { "ACIN_PLUGIN",
> +		"ACIN_REMOVAL", "ACIN_OVER_V" };
> +	irqreturn_t (*irq_funcs[])(int, void *) = { axp20x_irq_ac_plugin,
> +		axp20x_irq_ac_removal, axp20x_irq_ac_over_v };
> +	int i, irq, r, input;
> +
> +	if (!of_device_is_available(pdev->dev.of_node))
> +		return -ENODEV;

That's useless. If the device is not available, you're not going to be
probed in the first place.

> +	power = devm_kzalloc(&pdev->dev, sizeof(*power), GFP_KERNEL);
> +	if (!power)
> +		return -ENOMEM;
> +
> +	power->regmap = axp20x->regmap;
> +
> +	r = regmap_read(power->regmap, AXP20X_PWR_INPUT_STATUS, &input);
> +	if (r < 0)
> +		return r;
> +
> +	if (!!(input & AXP20X_PWR_STATUS_AC_VBUS_SHORT)) {
> +		dev_err(&pdev->dev, "AC is connected to VBUS. Use axp20x_usb_power-supply driver instead!");
> +		return -ENODEV;
> +	}

Can't that change over time? Can't we support both drivers at the same time?

> +	/* Enable ac voltage and current measurement */
> +	r = regmap_update_bits(power->regmap, AXP20X_ADC_EN1,
> +			AXP20X_ADC_EN1_ACIN_CURR | AXP20X_ADC_EN1_ACIN_VOLT,
> +			AXP20X_ADC_EN1_ACIN_CURR | AXP20X_ADC_EN1_ACIN_VOLT);
> +	if (r)
> +		return r;
> +
> +	psy_cfg.of_node = pdev->dev.of_node;
> +	psy_cfg.drv_data = power;
> +
> +	power->supply = devm_power_supply_register(&pdev->dev,
> +					&axp20x_ac_power_desc, &psy_cfg);
> +	if (IS_ERR(power->supply))
> +		return PTR_ERR(power->supply);
> +
> +	/* Request irqs after registering, as irqs may trigger immediately */
> +	for (i = 0; i < ARRAY_SIZE(irq_names); i++) {
> +		irq = platform_get_irq_byname(pdev, irq_names[i]);
> +		if (irq < 0) {
> +			dev_warn(&pdev->dev, "No IRQ for %s: %d\n",
> +				 irq_names[i], irq);
> +			continue;
> +		}
> +		irq = regmap_irq_get_virq(axp20x->regmap_irqc, irq);
> +		r = devm_request_any_context_irq(&pdev->dev, irq,
> +				irq_funcs[i], 0, DRVNAME, power);
> +		if (r < 0)
> +			dev_warn(&pdev->dev, "Error requesting %s IRQ: %d\n",
> +				 irq_names[i], r);
> +	}
> +
> +	return 0;
> +}
> +
> +static const struct of_device_id axp20x_ac_power_match[] = {
> +	{ .compatible = "x-powers,axp202-ac-power-supply" },
> +	{ }
> +};
> +MODULE_DEVICE_TABLE(of, axp20x_ac_power_match);
> +
> +static struct platform_driver axp20x_ac_power_driver = {
> +	.probe = axp20x_ac_power_probe,
> +	.driver = {
> +		.name = DRVNAME,
> +		.of_match_table = axp20x_ac_power_match,
> +	},
> +};
> +
> +module_platform_driver(axp20x_ac_power_driver);
> +
> +MODULE_AUTHOR("Bruno Prémont <bonbons-ud5FBsm0p/xEiooADzr8i9i2O/JbrIOy@public.gmane.org>");
> +MODULE_DESCRIPTION("AXP20x PMIC AC power supply status driver");
> +MODULE_LICENSE("GPL");
> -- 
> 2.8.0

Thanks!
Maxime

-- 
Maxime Ripard, Free Electrons
Embedded Linux, Kernel and Android engineering
http://free-electrons.com

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