linux-kernel - Re: [PATCH RFC] I2C: i2c-smbus: add device tree support

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Message-ID: <CAHp75VepT0ztJ3sLoM_Yw+yo9E3QLJaKNae_AQ3TMH=LbNeRfQ@mail.gmail.com>
Date:	Wed, 13 Apr 2016 20:58:49 +0300
From:	Andy Shevchenko <andy.shevchenko@...il.com>
To:	Andrea Merello <andrea.merello@...il.com>
Cc:	jdelvare@...e.de, Wolfram Sang <wsa@...-dreams.de>,
	linux-i2c@...r.kernel.org, devicetree <devicetree@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH RFC] I2C: i2c-smbus: add device tree support

On Wed, Apr 13, 2016 at 11:36 AM, Andrea Merello
<andrea.merello@...il.com> wrote:
> According to Documentation/i2c/smbus-protocol, a smbus controller driver
> that wants to hook-in smbus extensions support, can call
> i2c_setup_smbus_alert(). There are very few drivers that are currently
> doing this.
>
> However the i2c-smbus module can also work with any
> smbus-extensions-unaware I2C controller, as long as we provide an extra
> IRQ line connected to the I2C bus ALARM signal.
>
> This patch makes it possible to go this way via DT. Note that the DT node
> will indeed describe a (little) piece of HW, that is the routing of the
> ALARM signal to an IRQ line (so it seems a fair DT use to me, but RFC).
>
> Note that AFAICT, by design, i2c-smbus module pretends to be an I2C slave
> with address 0x0C (that is the alarm response address), and IMHO this is
> quite consistent with usage in the DT as a I2C child node.

> --- a/drivers/i2c/i2c-smbus.c
> +++ b/drivers/i2c/i2c-smbus.c

> @@ -137,20 +138,29 @@ static int smbalert_probe(struct i2c_client *ara,
>         struct i2c_smbus_alert_setup *setup = dev_get_platdata(&ara->dev);
>         struct i2c_smbus_alert *alert;
>         struct i2c_adapter *adapter = ara->adapter;
> +       struct device_node *of_node = ara->dev.of_node;

Perhaps fwnode_handle ?

>         int res;
> +       int irq_type;
>
>         alert = devm_kzalloc(&ara->dev, sizeof(struct i2c_smbus_alert),
>                              GFP_KERNEL);
>         if (!alert)
>                 return -ENOMEM;
>
> -       alert->alert_edge_triggered = setup->alert_edge_triggered;
> -       alert->irq = setup->irq;
> +       if (setup) {
> +               alert->alert_edge_triggered = setup->alert_edge_triggered;
> +               alert->irq = setup->irq;
> +       } else if (of_node) {
> +               alert->irq = irq_of_parse_and_map(of_node, 0);
> +               irq_type = irq_get_trigger_type(alert->irq);
> +               alert->alert_edge_triggered = (irq_type & IRQ_TYPE_EDGE_BOTH);
> +       }

-- 
With Best Regards,
Andy Shevchenko