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Message-ID: <CAOY=C6E-+uKQGbRDjNh5ZP9Wrmd+PNbt7djkBTzwe29=qA1_PA@mail.gmail.com>
Date: Sun, 27 Jan 2013 14:07:14 +0100
From: Stijn Devriendt <highguy@...il.com>
To: Roland Stigge <stigge@...com.de>
Cc: gregkh@...uxfoundation.org, grant.likely@...retlab.ca,
linus.walleij@...aro.org, linux-kernel@...r.kernel.org,
linux-arm-kernel@...ts.infradead.org, w.sang@...gutronix.de,
jbe@...gutronix.de, plagnioj@...osoft.com,
broonie@...nsource.wolfsonmicro.com, daniel-gl@....net,
rmallon@...il.com, sr@...x.de, wg@...ndegger.com,
mark.rutland@....com, nicolas.ferre@...el.com
Subject: Re: [PATCH 5/6 v14] gpio: Add device tree support to block GPIO API
On Tue, Jan 22, 2013 at 1:06 PM, Roland Stigge <stigge@...com.de> wrote:
> This patch adds device tree support to the block GPIO API.
>
> Signed-off-by: Roland Stigge <stigge@...com.de>
>
> ---
> Documentation/devicetree/bindings/gpio/gpio-block.txt | 36 ++++++
> drivers/gpio/Makefile | 1
> drivers/gpio/gpioblock-of.c | 100 ++++++++++++++++++
> 3 files changed, 137 insertions(+)
>
> --- /dev/null
> +++ linux-2.6/Documentation/devicetree/bindings/gpio/gpio-block.txt
> @@ -0,0 +1,36 @@
> +Block GPIO definition
> +=====================
> +
> +This binding specifies arbitrary blocks of gpios, combining gpios from one or
> +more GPIO controllers together, to form a word for r/w access.
> +
> +Required property:
> +- compatible: must be "linux,gpio-block"
> +
> +Required subnodes:
> +- the name will be the registered name of the block
> +- property "gpios" is a list of gpios for the respective block
> +
> +Example:
> +
> + blockgpio {
> + compatible = "linux,gpio-block";
> +
> + block0 {
> + gpios = <&gpio 3 0 0>,
> + <&gpio 3 1 0>;
> + };
> + block1 {
> + gpios = <&gpio 4 1 0>,
> + <&gpio 4 3 0>,
> + <&gpio 4 2 0>,
> + <&gpio 4 4 0>,
> + <&gpio 4 5 0>,
> + <&gpio 4 6 0>,
> + <&gpio 4 7 0>,
> + <&gpio 4 8 0>,
> + <&gpio 4 9 0>,
> + <&gpio 4 10 0>,
> + <&gpio 4 19 0>;
> + };
> + };
How do you see bindings for other kinds of drivers?
In my patchset, it's possible for other drivers to use gpio-blocks.
One example we have is a power sequencer with 2 pins attached
to GPIO pins. These 2 pins form a 2bit word to select power margining.
These 2 pins need to be set synchronously (as otherwise when going
from profile 0 to profile 3 you pass either profile 1 or profile 2 which
could be bad for hardware)
In the device-tree this is specified as:
powr@...0 {
// other properties
gpios = <&gpio 4 0
&gpio 5 0>;
};
Is this kind of integration also possible?
Regards,
Stijn
> --- linux-2.6.orig/drivers/gpio/Makefile
> +++ linux-2.6/drivers/gpio/Makefile
> @@ -5,6 +5,7 @@ ccflags-$(CONFIG_DEBUG_GPIO) += -DDEBUG
> obj-$(CONFIG_GPIOLIB) += gpiolib.o devres.o
> obj-$(CONFIG_OF_GPIO) += gpiolib-of.o
> obj-$(CONFIG_GPIO_ACPI) += gpiolib-acpi.o
> +obj-$(CONFIG_OF_GPIO) += gpioblock-of.o
>
> # Device drivers. Generally keep list sorted alphabetically
> obj-$(CONFIG_GPIO_GENERIC) += gpio-generic.o
> --- /dev/null
> +++ linux-2.6/drivers/gpio/gpioblock-of.c
> @@ -0,0 +1,100 @@
> +/*
> + * OF implementation for Block GPIO
> + *
> + * Copyright (C) 2012 Roland Stigge <stigge@...com.de>
> + *
> + * 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/kernel.h>
> +#include <linux/module.h>
> +#include <linux/platform_device.h>
> +#include <linux/gpio.h>
> +#include <linux/of.h>
> +#include <linux/of_gpio.h>
> +#include <linux/module.h>
> +#include <linux/slab.h>
> +#include <linux/err.h>
> +
> +static int gpioblock_of_probe(struct platform_device *pdev)
> +{
> + struct device_node *block;
> + unsigned *gpios;
> + int ngpio;
> + int ret;
> + struct gpio_block *gb;
> +
> + for_each_available_child_of_node(pdev->dev.of_node, block) {
> + int i;
> +
> + ngpio = of_gpio_count(block);
> + if (ngpio < 1) {
> + ret = -ENODEV;
> + goto err1;
> + }
> +
> + gpios = kzalloc(ngpio * sizeof(*gpios), GFP_KERNEL);
> + if (!gpios) {
> + ret = -ENOMEM;
> + goto err1;
> + }
> +
> + for (i = 0; i < ngpio; i++) {
> + ret = of_get_gpio(block, i);
> + if (ret < 0)
> + goto err2; /* expect -EPROBE_DEFER */
> + gpios[i] = ret;
> + }
> + gb = gpio_block_create(gpios, ngpio, block->name);
> + if (IS_ERR(gb)) {
> + dev_err(&pdev->dev,
> + "Error creating GPIO block from device tree\n");
> + ret = PTR_ERR(gb);
> + goto err2;
> + }
> + ret = gpio_block_register(gb);
> + if (ret < 0)
> + goto err3;
> +
> + kfree(gpios);
> + dev_info(&pdev->dev, "Registered gpio block %s: %d gpios\n",
> + block->name, ngpio);
> + }
> + return 0;
> +
> +err3:
> + gpio_block_free(gb);
> +err2:
> + kfree(gpios);
> +err1:
> + of_node_put(block);
> + return ret;
> +}
> +
> +#ifdef CONFIG_OF
> +static struct of_device_id gpioblock_of_match[] = {
> + { .compatible = "linux,gpio-block", },
> + { },
> +};
> +MODULE_DEVICE_TABLE(of, gpioblock_of_match);
> +#endif
> +
> +static struct platform_driver gpioblock_of_driver = {
> + .driver = {
> + .name = "gpio-block",
> + .owner = THIS_MODULE,
> + .of_match_table = of_match_ptr(gpioblock_of_match),
> +
> + },
> + .probe = gpioblock_of_probe,
> +};
> +
> +module_platform_driver(gpioblock_of_driver);
> +
> +MODULE_DESCRIPTION("GPIO Block driver");
> +MODULE_AUTHOR("Roland Stigge <stigge@...com.de>");
> +MODULE_LICENSE("GPL");
> +MODULE_ALIAS("platform:gpioblock-of");
--
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