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Message-Id: <20120403150430.EBA423E0436@localhost>
Date: Tue, 03 Apr 2012 09:04:30 -0600
From: Grant Likely <grant.likely@...retlab.ca>
To: Roland Stigge <stigge@...com.de>, arm@...nel.org,
linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
linus.walleij@...ricsson.com
Cc: Roland Stigge <stigge@...com.de>
Subject: Re: [PATCH] gpio: Device tree support for LPC32xx
On Tue, 3 Apr 2012 00:58:33 +0200, Roland Stigge <stigge@...com.de> wrote:
> This patch adds device tree support for gpio-lpc32xx.c
>
> Signed-off-by: Roland Stigge <stigge@...com.de>
>
> ---
>
> Applies to v3.4-rc1
>
> Can add this patch to the LPC32xx series for an update, if necessary.
>
> Thanks to Arnd Bergmann for the help with registering GPIO via OF!
Hi Roland,
Comments below.
>
> Documentation/devicetree/bindings/gpio/gpio_lpc32xx.txt | 71 ++++++++++++++++
> arch/arm/mach-lpc32xx/include/mach/gpio.h | 9 +-
> drivers/gpio/gpio-lpc32xx.c | 45 +++++++++-
> 3 files changed, 120 insertions(+), 5 deletions(-)
>
> --- /dev/null
> +++ linux-2.6/Documentation/devicetree/bindings/gpio/gpio_lpc32xx.txt
> @@ -0,0 +1,71 @@
> +NXP LPC32xx SoC GPIO controller
> +
> +Required properties:
> +- compatible: "nxp,lpc32xx-gpio"
> +- reg: Physical base address and length of the controller's registers.
> +- #address-cells: For indexing of the subnodes (GPIO groups of the SoC)
> +- #size-cells: Always 0
> +- #gpio-cells: Should be two. The first cell is the pin number and the
> + second cell is used to specify optional parameters:
> + - bit 0 specifies polarity (0 for normal, 1 for inverted)
Having #gpio-cells in the parent node doesn't make much sense when it
looks like the users reference the child node banks directly and which
have their own #gpio-cells properties.
> +
> +Required properties of sub-nodes which describe the GPIO groups of LPC32xx:
> +- gpio-controller: Marks the device node as a GPIO controller.
> +- #gpio-cells: Should be two. The first cell is the pin number and the
> + second cell is used to specify optional parameters:
> + - bit 0 specifies polarity (0 for normal, 1 for inverted)
> +- reg: Index of the GPIO group
> +- gpio-lines: Number of GPIOs in that subnode/GPIO group
The driver doesn't appear to be using the gpio-lines property. Is it
really necessary?
> +
> +Example:
> +
> + gpio: gpio@...28000 {
> + compatible = "nxp,lpc32xx-gpio";
> + reg = <0x40028000 0x1000>;
> + /* create a private address space for enumeration */
> + #address-cells = <1>;
> + #size-cells = <0>;
> + #gpio-cells = <2>;
> +
> + gpio_p0: gpio-bank@0 {
> + gpio-controller;
> + #gpio-cells = <2>;
> + gpio-lines = <8>;
> + reg = <0>;
> + };
> +
> + gpio_p1: gpio-bank@1 {
> + gpio-controller;
> + #gpio-cells = <2>;
> + gpio-lines = <24>;
> + reg = <1>;
> + };
> +
> + gpio_p2: gpio-bank@2 {
> + gpio-controller;
> + #gpio-cells = <2>;
> + gpio-lines = <13>;
> + reg = <2>;
> + };
> +
> + gpio_p3: gpio-bank@3 {
> + gpio-controller;
> + #gpio-cells = <2>;
> + gpio-lines = <6>;
> + reg = <3>;
> + };
> +
> + gpi_p3: gpio-bank@4 {
> + gpio-controller;
> + #gpio-cells = <2>;
> + gpio-lines = <28>;
> + reg = <4>;
> + };
> +
> + gpo_p3: gpio-bank@5 {
> + gpio-controller;
> + #gpio-cells = <2>;
> + gpio-lines = <24>;
> + reg = <5>;
> + };
> + };
> --- linux-2.6.orig/arch/arm/mach-lpc32xx/include/mach/gpio.h
> +++ linux-2.6/arch/arm/mach-lpc32xx/include/mach/gpio.h
> @@ -1 +1,8 @@
> -/* empty */
> +#ifndef __MACH_GPIO_H
> +#define __MACH_GPIO_H
> +
> +#include "gpio-lpc32xx.h"
> +
> +#define ARCH_NR_GPIOS (LPC32XX_GPO_P3_GRP + LPC32XX_GPO_P3_MAX)
> +
> +#endif /* __MACH_GPIO_H */
> --- linux-2.6.orig/drivers/gpio/gpio-lpc32xx.c
> +++ linux-2.6/drivers/gpio/gpio-lpc32xx.c
> @@ -21,6 +21,9 @@
> #include <linux/io.h>
> #include <linux/errno.h>
> #include <linux/gpio.h>
> +#include <linux/of_gpio.h>
> +#include <linux/platform_device.h>
> +#include <linux/module.h>
>
> #include <mach/hardware.h>
> #include <mach/platform.h>
> @@ -454,10 +457,44 @@ static struct lpc32xx_gpio_chip lpc32xx_
> },
> };
>
> -void __init lpc32xx_gpio_init(void)
> +static int __devinit lpc32xx_gpio_probe(struct platform_device *pdev)
> {
> - int i;
> + struct device_node *node;
>
> - for (i = 0; i < ARRAY_SIZE(lpc32xx_gpiochip); i++)
> - gpiochip_add(&lpc32xx_gpiochip[i].chip);
> + for_each_child_of_node(pdev->dev.of_node, node) {
> + if (of_device_is_available(node)) {
> + u32 index;
> + struct gpio_chip *chip;
> + if (of_property_read_u32(node, "reg", &index) < 0)
> + continue;
> + if (index >= ARRAY_SIZE(lpc32xx_gpiochip))
> + continue;
> + chip = &lpc32xx_gpiochip[index].chip;
> + chip->of_node = of_node_get(node);
> + gpiochip_add(chip);
> + }
> + }
> +
> + return 0;
> }
> +
> +static struct of_device_id lpc32xx_gpio_of_match[] __devinitdata = {
> + { .compatible = "nxp,lpc32xx-gpio", },
> + { },
> +};
> +
> +static struct platform_driver lpc32xx_gpio_driver = {
> + .driver = {
> + .name = "lpc32xx-gpio",
> + .owner = THIS_MODULE,
> + .of_match_table = lpc32xx_gpio_of_match,
> + },
> + .probe = lpc32xx_gpio_probe,
> +};
> +
> +static int __init lpc32xx_gpio_init(void)
> +{
> + return platform_driver_register(&lpc32xx_gpio_driver);
> +}
> +postcore_initcall(lpc32xx_gpio_init);
module_platform_driver() please. Also, now that deferred probe is
merged, there should no longer be any need to mess around with
initcall levels to get gpio drivers probed early.
g.
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