linux-kernel - Re: [PATCH v4 3/4] pinctrl: Qualcomm SPMI PMIC GPIO pin controller driver

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Message-ID: <1411564172.18580.69.camel@iivanov-dev>
Date:	Wed, 24 Sep 2014 16:09:32 +0300
From:	"Ivan T. Ivanov" <iivanov@...sol.com>
To:	Bjorn Andersson <bjorn.andersson@...ymobile.com>
Cc:	Linus Walleij <linus.walleij@...aro.org>,
	Grant Likely <grant.likely@...aro.org>,
	Rob Herring <robh+dt@...nel.org>,
	David Collins <collinsd@...eaurora.org>,
	Wu Fenglin <fenglinw@....qualcomm.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
	"linux-arm-msm@...r.kernel.org" <linux-arm-msm@...r.kernel.org>
Subject: Re: [PATCH v4 3/4] pinctrl: Qualcomm SPMI PMIC GPIO pin controller
 driver

On Tue, 2014-09-23 at 21:18 -0700, Bjorn Andersson wrote:
> On Mon 15 Sep 07:44 PDT 2014, Ivan T. Ivanov wrote:
> 

<snip>

> > +static int pmic_gpio_of_xlate(struct gpio_chip *chip,
> > +                             const struct of_phandle_args *gpio_desc,
> > +                             u32 *flags)
> > +{
> > +       if (chip->of_gpio_n_cells < 2)
> > +               return -EINVAL;
> > +
> > +       if (flags)
> > +               *flags = gpio_desc->args[1];
> > +
> > +       return gpio_desc->args[0] - PMIC_GPIO_PHYSICAL_OFFSET;
> > +}
> 
> If you change:
>  gpiochip_add_pin_range(&state->chip, dev_name(dev), 0, 0, npins);
> to:
>  gpiochip_add_pin_range(&state->chip, dev_name(dev), 1, 0, npins);
> 
> And you treat the gpio functions as taking the gpio number instead of pinctrl
> number (i.e. subtract 1 in those), then gpiolib will provide this function for
> you.
> 

I am unable to make this work. of_gpio_simple_xlate() didn't know that
GPIO range is offset with 1. Requesting last GPIO return error. And
debug output looks weird, for example:

# cat /sys/kernel/debug/gpio
...
GPIOs 220-255, platform/0.c000.gpios, 0.c000.gpios:
...

# cat /sys/kernel/debug/pinctrl/0.c000.gpios/gpio-ranges 
GPIO ranges handled:
1: 0.c000.gpios GPIOS [221 - 256] PINS [0 - 35]

Advice, please.

> [..]
> > +
> > +static const struct of_device_id pmic_gpio_of_match[] = {
> > +       { .compatible = "qcom,spmi-pmic-gpio" },
> 
> I think this should be more specific, because hopefully the spmi specification
> will outlive the current pmic gpio block.
> 
> So I think you need to list the pmic blocks here (e.g. "qcom,pm8941-gpio").

I can rename this to lovely "qcom,qpnp-gpio" :-), in this way driver
can outlive bus on which device is connected this time.

Regards,
Ivan


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