Subject: Re: [PATCH v6] PPC440EPx gpio driver

From: Anton Vorontsov <[email-masked]>
Date: Fri, 10 Oct 2008 01:18:52 +0400

On Thu, Oct 09, 2008 at 04:05:28PM -0400, Steven A. Falco wrote:
> This patch adds support for the GPIO functions of PPC40x and PPC44x
> SOCs.
> 
> Signed-off-by: Steve Falco <sfalco at harris.com>
> ---
> 
> I looked more closely at the datasheet.  Stefan is correct that the
> shadow registers are not needed for these processors, because they have
> separate registers for input and output.
> 
> I've incorporated the other changes, with one exception.  I want
> ppc4xx_gpio_get() to return 0 or 1 (rather than Anton's comment that any
> non-zero value is ok), because when you use the new "export feature" in
> sysfs, you see the raw value returned from ppc4xx_gpio_get().  So, without
> the !!  in the return statement, you would see a strange value, like 32768
> instead of 1:
> 
> 	# cd gpio208
> 	# cat value
> 	32768
> 
> So, I think it is worth sanitizing the return value here.

I think that nonzero == high assumption is also ok for the userspace.

Cc'ing David Brownell though.

> diff --git a/arch/powerpc/platforms/40x/Kconfig b/arch/powerpc/platforms/40x/Kconfig
> index a9260e2..aaada72 100644
> --- a/arch/powerpc/platforms/40x/Kconfig
> +++ b/arch/powerpc/platforms/40x/Kconfig
> @@ -139,6 +139,14 @@ config STB03xxx
>  	select IBM405_ERR77
>  	select IBM405_ERR51
>  
> +config PPC4xx_GPIO
> +	bool "PPC4xx GPIO support"
> +	depends on 40x
> +	select ARCH_REQUIRE_GPIOLIB
> +	select GENERIC_GPIO
> +	help
> +	  Enable gpiolib support for ppc40x based boards
> +
>  # 40x errata/workaround config symbols, selected by the CPU models above
>  
>  # All 405-based cores up until the 405GPR and 405EP have this errata.
> diff --git a/arch/powerpc/platforms/44x/Kconfig b/arch/powerpc/platforms/44x/Kconfig
> index 249ba01..eec5cb4 100644
> --- a/arch/powerpc/platforms/44x/Kconfig
> +++ b/arch/powerpc/platforms/44x/Kconfig
> @@ -127,6 +143,14 @@ config XILINX_VIRTEX440_GENERIC_BOARD
>  	  Most Virtex 5 designs should use this unless it needs to do some
>  	  special configuration at board probe time.
>  
> +config PPC4xx_GPIO
> +	bool "PPC4xx GPIO support"
> +	depends on 44x
> +	select ARCH_REQUIRE_GPIOLIB
> +	select GENERIC_GPIO
> +	help
> +	  Enable gpiolib support for ppc440 based boards
> +
>  # 44x specific CPU modules, selected based on the board above.
>  config 440EP
>  	bool
> diff --git a/arch/powerpc/sysdev/Makefile b/arch/powerpc/sysdev/Makefile
> index a90054b..35d5765 100644
> --- a/arch/powerpc/sysdev/Makefile
> +++ b/arch/powerpc/sysdev/Makefile
> @@ -35,6 +35,7 @@ obj-$(CONFIG_OF_RTC)		+= of_rtc.o
>  ifeq ($(CONFIG_PCI),y)
>  obj-$(CONFIG_4xx)		+= ppc4xx_pci.o
>  endif
> +obj-$(CONFIG_PPC4xx_GPIO)	+= ppc4xx_gpio.o
>  
>  # Temporary hack until we have migrated to asm-powerpc
>  ifeq ($(ARCH),powerpc)
> diff --git a/arch/powerpc/sysdev/ppc4xx_gpio.c b/arch/powerpc/sysdev/ppc4xx_gpio.c
> new file mode 100644
> index 0000000..b15aa5d
> --- /dev/null
> +++ b/arch/powerpc/sysdev/ppc4xx_gpio.c
> @@ -0,0 +1,225 @@
> +/*
> + * PPC4xx gpio driver
> + *
> + * Copyright (c) 2008 Harris Corporation
> + * Copyright (c) 2008 Sascha Hauer <[email-masked]>, Pengutronix
> + * Copyright (c) MontaVista Software, Inc. 2008.
> + *
> + * Author: Steve Falco <[email-masked]>
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License version 2
> + * as published by the Free Software Foundation.
> + *
> + * This program is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> + * GNU General Public License for more details.
> + *
> + * You should have received a copy of the GNU General Public License
> + * along with this program; if not, write to the Free Software
> + * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
> + */
> +
> +#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>
> +#include <linux/types.h>
> +
> +#define GPIO_MASK(gpio)		(0x80000000 >> (gpio))
> +#define GPIO_MASK2(gpio)	(0xc0000000 >> ((gpio) * 2))
> +
> +/* Physical GPIO register layout */
> +struct ppc4xx_gpio {
> +	__be32 or;
> +	__be32 tcr;
> +	__be32 osrl;
> +	__be32 osrh;
> +	__be32 tsrl;
> +	__be32 tsrh;
> +	__be32 odr;
> +	__be32 ir;
> +	__be32 rr1;
> +	__be32 rr2;
> +	__be32 rr3;
> +	__be32 reserved1;
> +	__be32 isr1l;
> +	__be32 isr1h;
> +	__be32 isr2l;
> +	__be32 isr2h;
> +	__be32 isr3l;
> +	__be32 isr3h;
> +};
> +
> +struct ppc4xx_gpio_chip {
> +	struct of_mm_gpio_chip mm_gc;
> +	spinlock_t lock;
> +};
> +
> +/*
> + * GPIO LIB API implementation for GPIOs
> + *
> + * There are a maximum of 32 gpios in each gpio controller.
> + */
> +
> +static inline struct ppc4xx_gpio_chip *
> +to_ppc4xx_gpiochip(struct of_mm_gpio_chip *mm_gc)
> +{
> +	return container_of(mm_gc, struct ppc4xx_gpio_chip, mm_gc);
> +}
> +
> +static int ppc4xx_gpio_get(struct gpio_chip *gc, unsigned int gpio)
> +{
> +	struct of_mm_gpio_chip *mm_gc = to_of_mm_gpio_chip(gc);
> +	struct ppc4xx_gpio __iomem *regs = mm_gc->regs;
> +
> +	return !!(in_be32(&regs->ir) & GPIO_MASK(gpio));
> +}
> +
> +static inline void
> +__ppc4xx_gpio_set(struct gpio_chip *gc, unsigned int gpio, int val)
> +{
> +	struct of_mm_gpio_chip *mm_gc = to_of_mm_gpio_chip(gc);
> +	struct ppc4xx_gpio __iomem *regs = mm_gc->regs;
> +
> +	if (val)
> +		out_be32(&regs->or, in_be32(&regs->or) | GPIO_MASK(gpio));
> +	else
> +		out_be32(&regs->or, in_be32(&regs->or) & ~GPIO_MASK(gpio));
> +}
> +
> +static void
> +ppc4xx_gpio_set(struct gpio_chip *gc, unsigned int gpio, int val)
> +{
> +	struct of_mm_gpio_chip *mm_gc = to_of_mm_gpio_chip(gc);
> +	struct ppc4xx_gpio_chip *chip = to_ppc4xx_gpiochip(mm_gc);
> +	unsigned long flags;
> +
> +	spin_lock_irqsave(&chip->lock, flags);
> +
> +	__ppc4xx_gpio_set(gc, gpio, val);
> +
> +	spin_unlock_irqrestore(&chip->lock, flags);
> +
> +	pr_debug("%s: gpio: %d val: %d\n", __func__, gpio, val);
> +}
> +
> +static int ppc4xx_gpio_dir_in(struct gpio_chip *gc, unsigned int gpio)
> +{
> +	struct of_mm_gpio_chip *mm_gc = to_of_mm_gpio_chip(gc);
> +	struct ppc4xx_gpio_chip *chip = to_ppc4xx_gpiochip(mm_gc);
> +	struct ppc4xx_gpio __iomem *regs = mm_gc->regs;
> +	unsigned long flags;
> +
> +	spin_lock_irqsave(&chip->lock, flags);
> +
> +	/* Disable open-drain function */
> +	out_be32(&regs->odr, in_be32(&regs->odr) & ~GPIO_MASK(gpio));

There are convenient functions to manipulate the bits:
clrbits32/setbits32/clrsetbits32.

> +
> +	/* Float the pin */
> +	out_be32(&regs->tcr, in_be32(&regs->tcr) & ~GPIO_MASK(gpio));
> +
> +	/* Bits 0-15 use TSRL/OSRL, bits 16-31 use TSRH/OSRH */
> +	if (gpio < 16) {
> +		out_be32(&regs->osrl,
> +			       	in_be32(&regs->osrl) & ~GPIO_MASK2(gpio));
> +		out_be32(&regs->tsrl,
> +			       	in_be32(&regs->tsrl) & ~GPIO_MASK2(gpio));
> +	} else {
> +		out_be32(&regs->osrh,
> +			       	in_be32(&regs->osrh) & ~GPIO_MASK2(gpio - 16));
> +		out_be32(&regs->tsrh,
> +			       	in_be32(&regs->tsrh) & ~GPIO_MASK2(gpio - 16));
> +	}
> +
> +	spin_unlock_irqrestore(&chip->lock, flags);
> +
> +	return 0;
> +}
> +
> +static int
> +ppc4xx_gpio_dir_out(struct gpio_chip *gc, unsigned int gpio, int val)
> +{
> +	struct of_mm_gpio_chip *mm_gc = to_of_mm_gpio_chip(gc);
> +	struct ppc4xx_gpio_chip *chip = to_ppc4xx_gpiochip(mm_gc);
> +	struct ppc4xx_gpio __iomem *regs = mm_gc->regs;
> +	unsigned long flags;
> +
> +	spin_lock_irqsave(&chip->lock, flags);
> +
> +	/* First set initial value */
> +	__ppc4xx_gpio_set(gc, gpio, val);
> +
> +	/* Disable open-drain function */
> +	out_be32(&regs->odr, in_be32(&regs->odr) & ~GPIO_MASK(gpio));
> +
> +	/* Drive the pin */
> +	out_be32(&regs->tcr, in_be32(&regs->tcr) | GPIO_MASK(gpio));
> +
> +	/* Bits 0-15 use TSRL, bits 16-31 use TSRH */
> +	if (gpio < 16) {
> +		out_be32(&regs->osrl,
> +			       	in_be32(&regs->osrl) & ~GPIO_MASK2(gpio));
> +		out_be32(&regs->tsrl,
> +			       	in_be32(&regs->tsrl) & ~GPIO_MASK2(gpio));
> +	} else {
> +		out_be32(&regs->osrh,
> +			       	in_be32(&regs->osrh) & ~GPIO_MASK2(gpio - 16));
> +		out_be32(&regs->tsrh,
> +			       	in_be32(&regs->tsrh) & ~GPIO_MASK2(gpio - 16));
> +	}
> +
> +	spin_unlock_irqrestore(&chip->lock, flags);
> +
> +	pr_debug("%s: gpio: %d val: %d\n", __func__, gpio, val);
> +
> +	return 0;
> +}
> +
> +static int __init ppc4xx_add_gpiochips(void)
> +{
> +	struct device_node *np;
> +
> +	for_each_compatible_node(np, NULL, "amcc,ppc4xx-gpio") {
> +		int ret;
> +		struct ppc4xx_gpio_chip *ppc4xx_gc;
> +		struct of_mm_gpio_chip *mm_gc;
> +		struct of_gpio_chip *of_gc;
> +		struct gpio_chip *gc;
> +
> +		ppc4xx_gc = kzalloc(sizeof(*ppc4xx_gc), GFP_KERNEL);
> +		if (!ppc4xx_gc) {
> +			ret = -ENOMEM;
> +			goto err;
> +		}
> +
> +		spin_lock_init(&ppc4xx_gc->lock);
> +
> +		mm_gc = &ppc4xx_gc->mm_gc;
> +		of_gc = &mm_gc->of_gc;
> +		gc = &of_gc->gc;
> +
> +		of_gc->gpio_cells = 2;
> +		gc->ngpio = 32;
> +		gc->direction_input = ppc4xx_gpio_dir_in;
> +		gc->direction_output = ppc4xx_gpio_dir_out;
> +		gc->get = ppc4xx_gpio_get;
> +		gc->set = ppc4xx_gpio_set;
> +
> +		ret = of_mm_gpiochip_add(np, mm_gc);
> +		if (ret)
> +			goto err;
> +		continue;
> +err:
> +		pr_err("%s: registration failed with status %d\n",
> +		       np->full_name, ret);
> +		kfree(ppc4xx_gc);
> +		/* try others anyway */
> +	}
> +	return 0;
> +}
> +arch_initcall(ppc4xx_add_gpiochips);

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