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Message-ID: <CACRpkdZ9wukeXmVbLSNYanWMUOouKduhmxgNyJ=iq-pCTQSAtQ@mail.gmail.com>
Date: Fri, 16 Aug 2013 16:05:30 +0200
From: Linus Walleij <linus.walleij@...aro.org>
To: Jonas Jensen <jonas.jensen@...il.com>
Cc: "linux-gpio@...r.kernel.org" <linux-gpio@...r.kernel.org>,
Grant Likely <grant.likely@...aro.org>,
"linux-arm-kernel@...ts.infradead.org"
<linux-arm-kernel@...ts.infradead.org>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
"arm@...nel.org" <arm@...nel.org>, Arnd Bergmann <arnd@...db.de>,
"devicetree@...r.kernel.org" <devicetree@...r.kernel.org>
Subject: Re: [PATCH v4] gpio: Add MOXA ART GPIO driver
On Mon, Jul 29, 2013 at 3:06 PM, Jonas Jensen <jonas.jensen@...il.com> wrote:
> Add GPIO driver for MOXA ART SoCs.
>
> Signed-off-by: Jonas Jensen <jonas.jensen@...il.com>
(...)
> +++ b/Documentation/devicetree/bindings/gpio/moxa,moxart-gpio.txt
This needs to be copied to devicetree@...r.kernel.org and I want
an ACK from some DT maintainer as well.
> @@ -0,0 +1,23 @@
> +MOXA ART GPIO Controller
> +
> +Required properties:
> +
> +- #gpio-cells : Should be 2
> +- compatible : Must be "moxa,moxart-gpio"
> +- reg : Should contain registers location and length
> + index 0 : input, output, and direction control
> + index 1 : enable/disable individual pins, pin 0-31
What? Why is the same block deploying these things in two
totally different places in memory?? Random HW engineer
having fun at work or...?
> +- gpio-ready-led : ready LED gpio, with zero flags
> +- gpio-reset-switch : reset switch gpio, with zero flags
This does not belong in the GPIO node, or in the GPIO
driver for that matter. This shall be handled by e.g. connecting
drivers/leds/leds-gpio.c to a GPIO using device tree by
selecting that driver in your config and do like this in your
device tree:
leds {
compatible = "gpio-leds";
user-led {
label = "user_led";
gpios = <&gpio0 2 0x1>;
default-state = "off";
linux,default-trigger = "heartbeat";
};
};
(Gives a headtbeat trigger as well, skip that if you don't
want it.)
We have a generic reset-over-gpio driver as well, see
drivers/power/reset/gpio-poweroff.c
> +++ b/drivers/gpio/gpio-moxart.c
> @@ -0,0 +1,189 @@
> +/*
> + * MOXA ART SoCs GPIO driver.
> + *
> + * Copyright (C) 2013 Jonas Jensen
> + *
> + * Jonas Jensen <jonas.jensen@...il.com>
> + *
> + * This file is licensed under the terms of the GNU General Public
> + * License version 2. This program is licensed "as is" without any
> + * warranty of any kind, whether express or implied.
> + */
> +
> +#include <linux/err.h>
> +#include <linux/init.h>
> +#include <linux/irq.h>
> +#include <linux/io.h>
> +#include <linux/gpio.h>
> +#include <linux/platform_device.h>
> +#include <linux/module.h>
> +#include <linux/of_address.h>
> +#include <linux/of_gpio.h>
> +#include <linux/pinctrl/consumer.h>
> +#include <linux/delay.h>
> +#include <linux/timer.h>
> +
> +#define GPIO_DATA_OUT 0x00
> +#define GPIO_DATA_IN 0x04
> +#define GPIO_PIN_DIRECTION 0x08
> +
> +static void __iomem *moxart_pincontrol_base;
> +static void __iomem *moxart_gpio_base;
> +
> +void moxart_gpio_enable(u32 gpio)
> +{
> + writel(readl(moxart_pincontrol_base) | gpio, moxart_pincontrol_base);
> +}
> +
> +void moxart_gpio_disable(u32 gpio)
> +{
> + writel(readl(moxart_pincontrol_base) & ~gpio, moxart_pincontrol_base);
> +}
> +
> +static int moxart_gpio_request(struct gpio_chip *chip, unsigned offset)
> +{
> + moxart_gpio_enable(1 << offset);
Do this:
#include <linux/bitops.h>
moxart_gpio_enable(BIT(offset));
Repeat the comment for every similar instance below.
> +static void moxart_gpio_set(struct gpio_chip *chip, unsigned offset, int value)
> +{
> + void __iomem *ioaddr = moxart_gpio_base + GPIO_DATA_OUT;
> + u32 reg = readl(ioaddr);
> +
> + (value) ? writel(reg | (1 << offset), ioaddr) :
> + writel(reg & ~(1 << offset), ioaddr);
Isn't that a bit hard to read?
if (value)
reg |= BIT(offset);
else
reg &= ~BIT(offset);
writel(reg, ioaddr);
> +static int moxart_gpio_get(struct gpio_chip *chip, unsigned offset)
> +{
> + u32 ret = readl(moxart_gpio_base + GPIO_PIN_DIRECTION);
> +
> + if (ret & (1 << offset))
> + ret = readl(moxart_gpio_base + GPIO_DATA_OUT) & (1 << offset);
> + else
> + ret = readl(moxart_gpio_base + GPIO_DATA_IN) & (1 << offset);
Use this construct:
if (ret & BIT(offset)
return !!(readl(moxart_gpio_base + GPIO_DATA_OUT) & BIT(offset));
return !!(readl(moxart_gpio_base + GPIO_DATA_IN) & BIT(offset));
> + ret = gpiochip_add(&moxart_gpio_chip);
> + if (ret)
> + dev_err(dev, "%s: gpiochip_add failed\n",
> + dev->of_node->full_name);
You need to bail out here, right? Not continue to do
dangerous stuff.
> + gpio_ready_led = of_get_named_gpio(dev->of_node,
> + "gpio-ready-led", 0);
> + if (!gpio_is_valid(gpio_ready_led)) {
> + dev_err(dev, "invalid gpio (gpio-ready-led): %d\n",
> + gpio_ready_led);
> + return gpio_ready_led;
> + }
> +
> + gpio_reset_switch = of_get_named_gpio(dev->of_node,
> + "gpio-reset-switch", 0);
> + if (!gpio_is_valid(gpio_reset_switch)) {
> + dev_err(dev, "invalid gpio (gpio-reset-switch): %d\n",
> + gpio_reset_switch);
> + return gpio_reset_switch;
> + }
Please get rid of this. Use standard drivers as described above.
> +static int __init moxart_gpio_init(void)
> +{
> + return platform_driver_register(&moxart_gpio_driver);
> +}
> +
> +postcore_initcall(moxart_gpio_init);
Do you really need to have them this early?
Yours,
Linus Walleij
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