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Date:   Mon, 15 Apr 2019 09:10:23 +0200
From:   Krzysztof Kozlowski <krzk@...nel.org>
To:     Matheus Castello <matheus@...tello.eng.br>
Cc:     sre@...nel.org, robh+dt@...nel.org, mark.rutland@....com,
        Chanwoo Choi <cw00.choi@...sung.com>,
        Bartłomiej Żołnierkiewicz 
        <b.zolnierkie@...sung.com>, lee.jones@...aro.org,
        linux-pm@...r.kernel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 1/4] power: supply: max17040: Add IRQ handler for low
 SOC alert

On Mon, 15 Apr 2019 at 03:49, Matheus Castello <matheus@...tello.eng.br> wrote:
>
> According datasheet max17040 has a pin for alert host for low SOC.
> This pin can be used as external interrupt, so we need to check for
> interrupts assigned for device and handle it.
>
> In hadler we are checking and storing fuel gauge registers values
> and send an uevent to notificate user space, so user space can decide
> save work or turn off since the alert demonstrate that the battery may
> no have the power to keep the system turned on for much longer.
>
> Signed-off-by: Matheus Castello <matheus@...tello.eng.br>
> ---
>  drivers/power/supply/max17040_battery.c | 69 +++++++++++++++++++++++--
>  1 file changed, 64 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/power/supply/max17040_battery.c b/drivers/power/supply/max17040_battery.c
> index 91cafc7bed30..8d2f8ed3f44c 100644
> --- a/drivers/power/supply/max17040_battery.c
> +++ b/drivers/power/supply/max17040_battery.c
> @@ -13,6 +13,7 @@
>  #include <linux/err.h>
>  #include <linux/i2c.h>
>  #include <linux/delay.h>
> +#include <linux/interrupt.h>
>  #include <linux/power_supply.h>
>  #include <linux/max17040_battery.h>
>  #include <linux/slab.h>
> @@ -160,21 +161,40 @@ static void max17040_get_status(struct i2c_client *client)
>                 chip->status = POWER_SUPPLY_STATUS_FULL;
>  }
>
> +static void max17040_check_changes(struct i2c_client *client)
> +{
> +       max17040_get_vcell(client);
> +       max17040_get_soc(client);
> +       max17040_get_online(client);
> +       max17040_get_status(client);
> +}
> +
>  static void max17040_work(struct work_struct *work)
>  {
>         struct max17040_chip *chip;
>
>         chip = container_of(work, struct max17040_chip, work.work);
> -
> -       max17040_get_vcell(chip->client);
> -       max17040_get_soc(chip->client);
> -       max17040_get_online(chip->client);
> -       max17040_get_status(chip->client);
> +       max17040_check_changes(chip->client);
>
>         queue_delayed_work(system_power_efficient_wq, &chip->work,
>                            MAX17040_DELAY);
>  }
>
> +static irqreturn_t max17040_thread_handler(int id, void *dev)
> +{
> +       struct max17040_chip *chip = dev;
> +       struct i2c_client *client = chip->client;
> +
> +       dev_warn(&client->dev, "IRQ: Alert battery low level");
> +       /* read registers */
> +       max17040_check_changes(chip->client);
> +
> +       /* send uevent */
> +       power_supply_changed(chip->battery);
> +
> +       return IRQ_HANDLED;
> +}
> +
>  static enum power_supply_property max17040_battery_props[] = {
>         POWER_SUPPLY_PROP_STATUS,
>         POWER_SUPPLY_PROP_ONLINE,
> @@ -217,6 +237,27 @@ static int max17040_probe(struct i2c_client *client,
>                 return PTR_ERR(chip->battery);
>         }
>
> +       /* check interrupt */
> +       if (client->irq) {
> +               int ret;
> +               unsigned int flags;
> +
> +               dev_info(&client->dev, "IRQ: enabled\n");
> +               flags = IRQF_TRIGGER_FALLING | IRQF_ONESHOT;
> +
> +               ret = devm_request_threaded_irq(&client->dev, client->irq, NULL,
> +                                               max17040_thread_handler, flags,
> +                                               chip->battery->desc->name,
> +                                               chip);
> +
> +               if (ret) {
> +                       client->irq = 0;
> +                       if (ret != -EBUSY)

Why not on EBUSY?

> +                               dev_warn(&client->dev,
> +                                       "Failed to get IRQ err %d\n", ret);
> +               }
> +       }
> +
>         max17040_reset(client);
>         max17040_get_version(client);
>
> @@ -224,6 +265,8 @@ static int max17040_probe(struct i2c_client *client,
>         queue_delayed_work(system_power_efficient_wq, &chip->work,
>                            MAX17040_DELAY);
>
> +       device_init_wakeup(&client->dev, 1);

Either you parse DT for wakeup-source property and use it... or you
unconditionally enable wakeup. In the second case - there is no point
to check later for device_may_wakeup(). Instead check the return value
of device_init_wakeup().

> +
>         return 0;
>  }
>
> @@ -244,6 +287,14 @@ static int max17040_suspend(struct device *dev)
>         struct max17040_chip *chip = i2c_get_clientdata(client);
>
>         cancel_delayed_work(&chip->work);
> +
> +       if (client->irq) {
> +               if (device_may_wakeup(dev))
> +                       enable_irq_wake(client->irq);
> +               else
> +                       disable_irq_wake(client->irq);

Did you try the wakeup from suspend? You do not have a disable_irq()
here which usually was needed for interrupts to work properly on
suspend. Maybe this was fixed?

Best regards,
Krzysztof

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