Subject: Re: [PATCH v3] powerpc: gpio driver for mpc8349/8572/8610 and compatible with OF bindings

From: Anton Vorontsov <[email-masked]>
Date: Mon, 22 Sep 2008 17:32:54 +0400

On Mon, Sep 22, 2008 at 08:32:34AM +0200, Peter Korsgaard wrote:
> Structured similar to the existing QE GPIO support.
> 
> Signed-off-by: Peter Korsgaard <[email-masked]>

Looks good to me, thanks.

Few comments below, might want to consider some of them if you want to.

> ---
>  Changes since v2:
>  - Clarified documentation as requested by Kumar.
> 
>  Changes since v1:
>  Incorporated feedback from Anton and Kumar:
>  - Core is also used on 8572/8610 so s/83xx/8xxx/
>  - Use fsl,mpc8572-gpio / fsl,mpc8610-gpio for 85xx/86xx as compatible
>  - Use shadowed data register to handle open drain outputs
>  - Expandend dts binding doc, use 8347 as example instead of 8349
>  - Misc small cleanups
> 
>  .../powerpc/dts-bindings/fsl/8xxx_gpio.txt         |   40 +++++
>  arch/powerpc/sysdev/Kconfig                        |    9 +
>  arch/powerpc/sysdev/Makefile                       |    1 +
>  arch/powerpc/sysdev/mpc8xxx_gpio.c                 |  170 ++++++++++++++++++++
>  4 files changed, 220 insertions(+), 0 deletions(-)
>  create mode 100644 Documentation/powerpc/dts-bindings/fsl/8xxx_gpio.txt
>  create mode 100644 arch/powerpc/sysdev/mpc8xxx_gpio.c
> 
> diff --git a/Documentation/powerpc/dts-bindings/fsl/8xxx_gpio.txt b/Documentation/powerpc/dts-bindings/fsl/8xxx_gpio.txt
> new file mode 100644
> index 0000000..26c29c4
> --- /dev/null
> +++ b/Documentation/powerpc/dts-bindings/fsl/8xxx_gpio.txt
> @@ -0,0 +1,40 @@
> +GPIO controllers on MPC8xxx SoCs
> +
> +This is for the non-QE/CPM/GUTs GPIO controllers as found on
> +8349, 8572, 8610 and compatible.
> +
> +Every GPIO controller node must have #gpio-cells property defined,
> +this information will be used to translate gpio-specifiers.
> +
> +Required properties:
> +- compatible : "fsl,<CHIP>-gpio" followed by "fsl,mpc8349-gpio" for
> +  83xx, "fsl,mpc8572-gpio" for 85xx and "fsl,mpc8610-gpio" for 86xx.
> +- #gpio-cells : Should be two. The first cell is the pin number and the
> +  second cell is used to specify optional parameters (currently unused).
> + - interrupts : Interrupt mapping for GPIO IRQ (currently unused).
> + - interrupt-parent : Phandle for the interrupt controller that
> +   services interrupts for this device.
> +- gpio-controller : Marks the port as GPIO controller.
> +
> +Example of gpio-controller nodes for a MPC8347 SoC:
> +
> +	gpio1: gpio-controller@c00 {
> +		#gpio-cells = <2>;
> +		compatible = "fsl,mpc8347-gpio, fsl,mpc8349-gpio";

Some quotes are missing. Should be "fsl,mpc8347-gpio",
"fsl,mpc8349-gpio";

> +		reg = <0xc00 0x100>;
> +		interrupts = <74 0x8>;
> +		interrupt-parent = <&ipic>;
> +		gpio-controller;
> +	};
> +
> +	gpio2: gpio-controller@d00 {
> +		#gpio-cells = <2>;
> +		compatible = "fsl,mpc8347-gpio, fsl,mpc8349-gpio";

Ditto.

> +		reg = <0xd00 0x100>;
> +		interrupts = <75 0x8>;
> +		interrupt-parent = <&ipic>;
> +		gpio-controller;
> +	};
> +
> +See booting-without-of.txt for details of how to specify GPIO
> +information for devices.
> diff --git a/arch/powerpc/sysdev/Kconfig b/arch/powerpc/sysdev/Kconfig
> index 72fb35b..a11cc8f 100644
> --- a/arch/powerpc/sysdev/Kconfig
> +++ b/arch/powerpc/sysdev/Kconfig
> @@ -6,3 +6,12 @@ config PPC4xx_PCI_EXPRESS
>  	bool
>  	depends on PCI && 4xx
>  	default n
> +
> +config MPC8xxx_GPIO
> +	bool "MPC8xxx GPIO support"
> +	depends on PPC_MPC831x || PPC_MPC834x || PPC_MPC837x || PPC_85xx || PPC_86xx
> +	select GENERIC_GPIO
> +	select ARCH_REQUIRE_GPIOLIB
> +	help
> +	  Say Y here if you're going to use hardware that connects to the
> +	  MPC831x/834x/837x/8572/8610 GPIOs.
> diff --git a/arch/powerpc/sysdev/Makefile b/arch/powerpc/sysdev/Makefile
> index a90054b..e410764 100644
> --- a/arch/powerpc/sysdev/Makefile
> +++ b/arch/powerpc/sysdev/Makefile
> @@ -15,6 +15,7 @@ obj-$(CONFIG_FSL_SOC)		+= fsl_soc.o
>  obj-$(CONFIG_FSL_PCI)		+= fsl_pci.o $(fsl-msi-obj-y)
>  obj-$(CONFIG_FSL_LBC)		+= fsl_lbc.o
>  obj-$(CONFIG_FSL_GTM)		+= fsl_gtm.o
> +obj-$(CONFIG_MPC8xxx_GPIO)	+= mpc8xxx_gpio.o
>  obj-$(CONFIG_RAPIDIO)		+= fsl_rio.o
>  obj-$(CONFIG_TSI108_BRIDGE)	+= tsi108_pci.o tsi108_dev.o
>  obj-$(CONFIG_QUICC_ENGINE)	+= qe_lib/
> diff --git a/arch/powerpc/sysdev/mpc8xxx_gpio.c b/arch/powerpc/sysdev/mpc8xxx_gpio.c
> new file mode 100644
> index 0000000..3c1f608
> --- /dev/null
> +++ b/arch/powerpc/sysdev/mpc8xxx_gpio.c
> @@ -0,0 +1,170 @@
> +/*
> + * GPIOs on MPC8349/8572/8610 and compatible
> + *
> + * Copyright (C) 2008 Peter Korsgaard <[email-masked]>
> + *
> + * 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/kernel.h>
> +#include <linux/init.h>
> +#include <linux/spinlock.h>
> +#include <linux/io.h>
> +#include <linux/of.h>
> +#include <linux/of_gpio.h>
> +#include <linux/gpio.h>
> +
> +#define MPC8XXX_GPIO_PINS	32
> +
> +#define GPIO_DIR		0x00
> +#define GPIO_ODR		0x04
> +#define GPIO_DAT		0x08
> +#define GPIO_IER		0x0c
> +#define GPIO_IMR		0x10
> +#define GPIO_ICR		0x14

This is better described in a struct. Will save few characters,
and just looks nicer. That is,

mm->regs + GPIO_DAT

vs.

&mm->regs->dat

> +struct mpc8xxx_gpio_chip {
> +	struct of_mm_gpio_chip mm_gc;
> +	spinlock_t lock;
> +
> +	/* shadowed data register to be able to clear/set output pins in
> +	   open drain mode safely */

Why not a canonical comment?

/*
 * Multi-line
 * comment.
 */

> +	u32 data;
> +};
> +
> +static inline u32 mpc8xxx_gpio2mask(unsigned int gpio)
> +{
> +	return 1u << (MPC8XXX_GPIO_PINS - 1 - gpio);

`u` isn't necessary.

> +}
> +
> +static inline struct mpc8xxx_gpio_chip *
> +to_mpc8xxx_gpio_chip(struct of_mm_gpio_chip *mm)
> +{
> +	return container_of(mm, struct mpc8xxx_gpio_chip, mm_gc);
> +}
> +
> +static void mpc8xxx_gpio_save_regs(struct of_mm_gpio_chip *mm)
> +{
> +	struct mpc8xxx_gpio_chip *mpc8xxx_gc = to_mpc8xxx_gpio_chip(mm);
> +
> +	mpc8xxx_gc->data = in_be32(mm->regs + GPIO_DAT);
> +}
> +
> +static int mpc8xxx_gpio_get(struct gpio_chip *gc, unsigned int gpio)
> +{
> +	struct of_mm_gpio_chip *mm = to_of_mm_gpio_chip(gc);
> +
> +	return !!(in_be32(mm->regs + GPIO_DAT) & mpc8xxx_gpio2mask(gpio));

No need for !!. gpio api spec says that you may return any
value != 0 for the logical 1. Negative values are ok.

> +}
> +
> +static void mpc8xxx_gpio_set(struct gpio_chip *gc, unsigned int gpio, int val)
> +{
> +	struct of_mm_gpio_chip *mm = to_of_mm_gpio_chip(gc);
> +	struct mpc8xxx_gpio_chip *mpc8xxx_gc = to_mpc8xxx_gpio_chip(mm);
> +	unsigned long flags;
> +
> +	spin_lock_irqsave(&mpc8xxx_gc->lock, flags);
> +
> +	if (val)
> +		mpc8xxx_gc->data |= mpc8xxx_gpio2mask(gpio);
> +	else
> +		mpc8xxx_gc->data &= ~mpc8xxx_gpio2mask(gpio);
> +
> +	out_be32(mm->regs + GPIO_DAT, mpc8xxx_gc->data);
> +
> +	spin_unlock_irqrestore(&mpc8xxx_gc->lock, flags);
> +}
> +
> +static int mpc8xxx_gpio_dir_in(struct gpio_chip *gc, unsigned int gpio)
> +{
> +	struct of_mm_gpio_chip *mm = to_of_mm_gpio_chip(gc);
> +	struct mpc8xxx_gpio_chip *mpc8xxx_gc = to_mpc8xxx_gpio_chip(mm);
> +	unsigned long flags;
> +
> +	spin_lock_irqsave(&mpc8xxx_gc->lock, flags);
> +
> +	out_be32(mm->regs + GPIO_DIR,
> +		 in_be32(mm->regs + GPIO_DIR) & ~mpc8xxx_gpio2mask(gpio));

Would look better if you'd use clrbits32().

> +
> +	spin_unlock_irqrestore(&mpc8xxx_gc->lock, flags);
> +
> +	return 0;
> +}
> +
> +static int mpc8xxx_gpio_dir_out(struct gpio_chip *gc, unsigned int gpio, int val)
> +{
> +	struct of_mm_gpio_chip *mm = to_of_mm_gpio_chip(gc);
> +	struct mpc8xxx_gpio_chip *mpc8xxx_gc = to_mpc8xxx_gpio_chip(mm);
> +	unsigned long flags;
> +
> +	mpc8xxx_gpio_set(gc, gpio, val);
> +
> +	spin_lock_irqsave(&mpc8xxx_gc->lock, flags);
> +	out_be32(mm->regs + GPIO_DIR,
> +		 in_be32(mm->regs + GPIO_DIR) | mpc8xxx_gpio2mask(gpio));

setbits32().

> +
> +	spin_unlock_irqrestore(&mpc8xxx_gc->lock, flags);
> +
> +	return 0;
> +}
> +
> +static int __init mpc8xxx_add_controller(struct device_node *np)
> +{

You don't check return value for this function. `void' return type
would work.

> +	struct mpc8xxx_gpio_chip *mpc8xxx_gc;
> +	struct of_mm_gpio_chip *mm_gc;
> +	struct of_gpio_chip *of_gc;
> +	struct gpio_chip *gc;
> +	int ret;
> +
> +	mpc8xxx_gc = kzalloc(sizeof(*mpc8xxx_gc), GFP_KERNEL);
> +	if (!mpc8xxx_gc) {
> +		ret = -ENOMEM;
> +		goto err;
> +	}
> +
> +	spin_lock_init(&mpc8xxx_gc->lock);
> +
> +	mm_gc = &mpc8xxx_gc->mm_gc;
> +	of_gc = &mm_gc->of_gc;
> +	gc = &of_gc->gc;
> +
> +	mm_gc->save_regs = mpc8xxx_gpio_save_regs;
> +	of_gc->gpio_cells = 2;
> +	gc->ngpio = MPC8XXX_GPIO_PINS;
> +	gc->direction_input = mpc8xxx_gpio_dir_in;
> +	gc->direction_output = mpc8xxx_gpio_dir_out;
> +	gc->get = mpc8xxx_gpio_get;
> +	gc->set = mpc8xxx_gpio_set;
> +
> +	ret = of_mm_gpiochip_add(np, mm_gc);
> +	if (ret)
> +		goto err;
> +
> +	return 0;
> +
> +err:
> +	pr_err("%s: registration failed with status %d\n",
> +	       np->full_name, ret);
> +	kfree(mpc8xxx_gc);
> +
> +	return ret;
> +}
> +
> +static int __init mpc8xxx_add_gpiochips(void)
> +{
> +	struct device_node *np;
> +
> +	for_each_compatible_node(np, NULL, "fsl,mpc8349-gpio")
> +		mpc8xxx_add_controller(np);
> +
> +	for_each_compatible_node(np, NULL, "fsl,mpc8572-gpio")
> +		mpc8xxx_add_controller(np);
> +
> +	for_each_compatible_node(np, NULL, "fsl,mpc8610-gpio")
> +		mpc8xxx_add_controller(np);
> +
> +	return 0;
> +}
> +arch_initcall(mpc8xxx_add_gpiochips);
> -- 
> 1.5.6.3

-- 
Anton Vorontsov
email: [email-masked]
irc://irc.freenode.net/bd2