linux-kernel - Re: [PATCH 0/4] Pinmux subsystem

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Message-ID: <BANLkTi=TDiAziQU0fYBiK_Npk0x50av7tA@mail.gmail.com>
Date:	Tue, 17 May 2011 10:57:11 +0900
From:	Kyungmin Park <kmpark@...radead.org>
To:	Linus Walleij <linus.walleij@...aro.org>
Cc:	Andrew Lunn <andrew@...n.ch>, linux-kernel@...r.kernel.org,
	Grant Likely <grant.likely@...retlab.ca>,
	Martin Persson <martin.persson@...ricsson.com>,
	Lee Jones <lee.jones@...aro.org>,
	linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH 0/4] Pinmux subsystem

Hi,

In real scenario, we can set the full pins at once, but sometimes it
needs to set the function only one,

e.g.,

static void __init goni_radio_init(void)
{
        int gpio;

        gpio = S5PV210_GPJ2(4);                 /* XMSMDATA_4 */
        gpio_request(gpio, "FM_INT");
        s3c_gpio_cfgpin(gpio, S3C_GPIO_SFN(0xf));
        i2c1_devs[0].irq = gpio_to_irq(gpio);

        gpio = S5PV210_GPJ2(5);                 /* XMSMDATA_5 */
        gpio_request(gpio, "FM_RST");
        gpio_direction_output(gpio, 1);
}

In this case we only need to set the function at interrupt by like
s3c_gpio_cfgpin(gpio, S3C_GPIO_SFN(0xf));
So pinmux function provides this feature also.

How do you think?

Thank you,
Kyungmin Park


On Mon, May 16, 2011 at 2:50 AM, Linus Walleij <linus.walleij@...aro.org> wrote:
> 2011/5/15 Andrew Lunn <andrew@...n.ch>:
>
>> With a bit of scripting, came to the following results. Each line is
>> on pinmux function description what would be needed in the driver. The
>> number at the front says how many boards would use it. In total there
>> are 33 descriptions needed. Of these, 18 are used only once. This to
>> me suggests the board needs to be able to specify a pin description
>> when there is no reuse with other boards.
>
> As indicated elsewhere in this thread, a pinmux driver can pass in
> platform/package/board/system data just like any other platform
> driver in the kernel tree can.
>
> You will have to specify it somehow in a custom header file, just
> like with any other platform driver.
>
> Example from:
> arch/arm/mach-orion5x/ls-chl-setup.c:
>
> static struct gpio_led lschl_led_pins[] = {
>        {
>                .name = "alarm:red",
>                .gpio = LSCHL_GPIO_LED_ALARM,
>                .active_low = 1,
>        }, {
>                .name = "info:amber",
>                .gpio = LSCHL_GPIO_LED_INFO,
>                .active_low = 1,
>        }, {
>                .name = "func:blue:top",
>                .gpio = LSCHL_GPIO_LED_FUNC,
>                .active_low = 1,
>        }, {
>                .name = "power:blue:bottom",
>                .gpio = LSCHL_GPIO_LED_PWR,
>        },
> };
>
> static struct gpio_led_platform_data lschl_led_data = {
>        .leds = lschl_led_pins,
>        .num_leds = ARRAY_SIZE(lschl_led_pins),
> };
>
> static struct platform_device lschl_leds = {
>        .name = "leds-gpio",
>        .id = -1,
>        .dev = {
>                .platform_data = &lschl_led_data,
>        },
> };
>
> Still, the driver for these LEDs is in
> drivers/leds/leds-gpio.c and the above structure is
> described in include/linux/leds.h
>
> There is no difference between this and letting
> drivers/pinmux/pinmux-orion.c have a header file in
> include/linux/pinmux/orion.h and pass in necessary board
> data that way.
>
> Are we now in agreement that this will work just fine?
>
> Yours,
> Linus Walleij
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