Patchwork PPC440EPx gpio driver

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Submitter Steven A. Falco
Date Oct. 9, 2008, 6:04 p.m.
Message ID <48EE47C1.1000303@harris.com>
Download mbox | patch
Permalink /patch/3628/
State Superseded, archived
Headers show

Comments

Steven A. Falco - Oct. 9, 2008, 6:04 p.m.
I've moved the config variable to platforms/44x, and added the #include
of linux/types.h.

Since I don't have any PPC405 boards, I am unable to test with that CPU.
So, I am reluctant to add the config variable to platforms/40x.  It
would be trivial to add, if someone else has a suitable setup and could
run a test.

Signed-off-by: Steve Falco <sfalco at harris.com>
Stefan Roese - Oct. 9, 2008, 6:46 p.m.
Steve,

On Thursday 09 October 2008, Steven A. Falco wrote:
> I've moved the config variable to platforms/44x, and added the #include
> of linux/types.h.
>
> Since I don't have any PPC405 boards, I am unable to test with that CPU.
> So, I am reluctant to add the config variable to platforms/40x.  It
> would be trivial to add, if someone else has a suitable setup and could
> run a test.

Yes, please add it and I'll run a test tomorrow on my 405EP system.

It would be great if you could generate a git style patch where you put the 
patch description on top of the mail and can put those comments (like changes 
between versions) below the "---" line. Those comments will not appear in the 
git history after applying. And then please add a version number to the 
subject. Example:

[PATCH v2] powerpc/4xx: Add 4xx gpio driver

Some more comments below.

> Signed-off-by: Steve Falco <sfalco at harris.com>
>
> diff --git a/arch/powerpc/include/asm/ppc4xx.h
> b/arch/powerpc/include/asm/ppc4xx.h index 033039a..589ff5c 100644
> --- a/arch/powerpc/include/asm/ppc4xx.h
> +++ b/arch/powerpc/include/asm/ppc4xx.h
> @@ -13,6 +13,30 @@
>  #ifndef __ASM_POWERPC_PPC4xx_H__
>  #define __ASM_POWERPC_PPC4xx_H__
>
> +#include <linux/types.h>
> +
> +/* GPIO */
> +struct ppc4xx_gpio {
> +	__be32 gpio_or;
> +	__be32 gpio_tcr;
> +	__be32 gpio_osrl;
> +	__be32 gpio_osrh;
> +	__be32 gpio_tsrl;
> +	__be32 gpio_tsrh;
> +	__be32 gpio_odr;
> +	__be32 gpio_ir;
> +	__be32 gpio_rr1;
> +	__be32 gpio_rr2;
> +	__be32 gpio_rr3;
> +	__be32 reserved1;
> +	__be32 gpio_isr1l;
> +	__be32 gpio_isr1h;
> +	__be32 gpio_isr2l;
> +	__be32 gpio_isr2h;
> +	__be32 gpio_isr3l;
> +	__be32 gpio_isr3h;
> +};
> +

Not sure if we really need those defines in this header. They are only 
referenced by the gpio driver so why not move it to the driver instead?

>  extern void ppc4xx_reset_system(char *cmd);
>
>  #endif /* __ASM_POWERPC_PPC4xx_H__ */
> 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
> +

Please add gpio support for 40x as well. I'll test it tomorrow.

>  # 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..d401eba
> --- /dev/null
> +++ b/arch/powerpc/sysdev/ppc4xx_gpio.c
> @@ -0,0 +1,239 @@
> +/*
> + * PPC4xx gpio driver
> + *
> + * Copyright (c) 2008 Harris Corporation
> + * Copyright (c) 2008 Sascha Hauer <s.hauer@pengutronix.de>, Pengutronix
> + * Copyright (c) MontaVista Software, Inc. 2008.
> + *
> + * Author: Steve Falco <sfalco@harris.com>
> + *
> + * 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>
> +
> +#include <asm/ppc4xx.h>
> +
> +struct ppc4xx_gpio_chip {
> +	struct of_mm_gpio_chip mm_gc;
> +	spinlock_t lock;
> +	u32 shadow_or;
> +	u32 shadow_tcr;
> +	u32 shadow_osrl;
> +	u32 shadow_osrh;
> +	u32 shadow_tsrl;
> +	u32 shadow_tsrh;
> +	u32 shadow_odr;
> +};

Do we really need all those shadow registers? Access to the "real" registers 
is done while holding the spinlock.

> +
> +/*
> + * GPIO LIB API implementation for GPIOs
> + *
> + * There are a maximum of 64 gpios, spread over two sets of control
> registers. + * The sets are called GPIO0 and GPIO1.  Each set is managed
> separately, so + * there will be two entried in the .dts file.
> + */
> +
> +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;
> +	u32 ret;
> +
> +	ret = (in_be32(&regs->gpio_ir) >> (31 - gpio)) & 1;
> +
> +	return ret;

	return in_be32(&regs->gpio_ir) >> (31 - gpio)) & 1;

should be enough.

> +}
> +
> +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_chip *chip = to_ppc4xx_gpiochip(mm_gc);
> +	struct ppc4xx_gpio __iomem *regs = mm_gc->regs;
> +
> +	if (val)
> +		chip->shadow_or |= 1 << (31 - gpio);

This "1 << (31 - gpio)" is used quite often. Perhaps it makes sense to use a 
macro here to make the code better readable.

> +	else
> +		chip->shadow_or &= ~(1 << (31 - gpio));
> +	out_be32(&regs->gpio_or, chip->shadow_or);
> +}
> +
> +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 */
> +	chip->shadow_odr &= ~(1 << (31 - gpio));
> +	out_be32(&regs->gpio_odr, chip->shadow_odr);
> +
> +	/* Float the pin */
> +	chip->shadow_tcr &= ~(1 << (31 - gpio));
> +	out_be32(&regs->gpio_tcr, chip->shadow_tcr);
> +
> +	/* Bits 0-15 use TSRL/OSRL, bits 16-31 use TSRH/OSRH */
> +	if (gpio < 16) {
> +		chip->shadow_osrl &= ~(3 << ((15 - gpio) * 2));
> +		out_be32(&regs->gpio_osrl, chip->shadow_osrl);
> +
> +		chip->shadow_tsrl &= ~(3 << ((15 - gpio) * 2));
> +		out_be32(&regs->gpio_tsrl, chip->shadow_tsrl);
> +	} else {
> +		chip->shadow_osrh &= ~(3 << ((31 - gpio) * 2));
> +		out_be32(&regs->gpio_osrh, chip->shadow_osrh);
> +
> +		chip->shadow_tsrh &= ~(3 << ((31 - gpio) * 2));
> +		out_be32(&regs->gpio_tsrh, chip->shadow_tsrh);
> +	}
> +
> +	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 */
> +	chip->shadow_odr &= ~(1 << (31 - gpio));
> +	out_be32(&regs->gpio_odr, chip->shadow_odr);
> +
> +	/* Drive the pin */
> +	chip->shadow_tcr |= (1 << (31 - gpio));
> +	out_be32(&regs->gpio_tcr, chip->shadow_tcr);
> +
> +	/* Bits 0-15 use TSRL, bits 16-31 use TSRH */
> +	if (gpio < 16) {
> +		chip->shadow_osrl &= ~(3 << ((15 - gpio) * 2));
> +		out_be32(&regs->gpio_osrl, chip->shadow_osrl);
> +
> +		chip->shadow_tsrl &= ~(3 << ((15 - gpio) * 2));
> +		out_be32(&regs->gpio_tsrl, chip->shadow_tsrl);
> +	} else {
> +		chip->shadow_osrh &= ~(3 << ((31 - gpio) * 2));
> +		out_be32(&regs->gpio_osrh, chip->shadow_osrh);
> +
> +		chip->shadow_tsrh &= ~(3 << ((31 - gpio) * 2));
> +		out_be32(&regs->gpio_tsrh, chip->shadow_tsrh);
> +	}
> +
> +	spin_unlock_irqrestore(&chip->lock, flags);
> +
> +	pr_debug("%s: gpio: %d val: %d\n", __func__, gpio, val);
> +
> +	return 0;
> +}
> +
> +static void __init ppc4xx_gpio_save_regs(struct of_mm_gpio_chip *mm_gc)
> +{
> +	struct ppc4xx_gpio_chip *chip = to_ppc4xx_gpiochip(mm_gc);
> +	struct ppc4xx_gpio __iomem *regs = mm_gc->regs;
> +
> +	chip->shadow_or = in_be32(&regs->gpio_or);
> +	chip->shadow_tcr = in_be32(&regs->gpio_tcr);
> +	chip->shadow_osrl = in_be32(&regs->gpio_osrl);
> +	chip->shadow_osrh = in_be32(&regs->gpio_osrh);
> +	chip->shadow_tsrl = in_be32(&regs->gpio_tsrl);
> +	chip->shadow_tsrh = in_be32(&regs->gpio_tsrh);
> +	chip->shadow_odr = in_be32(&regs->gpio_odr);
> +}
> +
> +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;
> +
> +		mm_gc->save_regs = ppc4xx_gpio_save_regs;
> +		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);

This probably crashes if the kzalloc() fails above.

> +		/* try others anyway */
> +	}
> +	return 0;
> +}
> +arch_initcall(ppc4xx_add_gpiochips);
> _______________________________________________
> Linuxppc-dev mailing list
> Linuxppc-dev@ozlabs.org
> https://ozlabs.org/mailman/listinfo/linuxppc-dev


Best regards,
Stefan
Anton Vorontsov - Oct. 9, 2008, 7:03 p.m.
On Thu, Oct 09, 2008 at 08:46:44PM +0200, Stefan Roese wrote:
[...]
> > +struct ppc4xx_gpio_chip {
> > +	struct of_mm_gpio_chip mm_gc;
> > +	spinlock_t lock;
> > +	u32 shadow_or;
> > +	u32 shadow_tcr;
> > +	u32 shadow_osrl;
> > +	u32 shadow_osrh;
> > +	u32 shadow_tsrl;
> > +	u32 shadow_tsrh;
> > +	u32 shadow_odr;
> > +};
> 
> Do we really need all those shadow registers? Access to the "real" registers 
> is done while holding the spinlock.

The shadowed registers aren't about holding a spinlock, but are
about open drain pins and the fact that some GPIO controllers are
using single "data" register for "read state", "set state" and
"clear state" GPIO operations.

See Grant's reply:

http://ozlabs.org/pipermail/linuxppc-dev/2008-January/050826.html

(I didn't look for the hardware details of this driver, so I don't
know if the driver really needs to shadow the registers.)

[...]
> > +	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;
> > +
> > +		mm_gc->save_regs = ppc4xx_gpio_save_regs;
> > +		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);
> 
> This probably crashes if the kzalloc() fails above.

kfree(NULL); is defined to be a no-op.


Thanks,

Patch

diff --git a/arch/powerpc/include/asm/ppc4xx.h b/arch/powerpc/include/asm/ppc4xx.h
index 033039a..589ff5c 100644
--- a/arch/powerpc/include/asm/ppc4xx.h
+++ b/arch/powerpc/include/asm/ppc4xx.h
@@ -13,6 +13,30 @@ 
 #ifndef __ASM_POWERPC_PPC4xx_H__
 #define __ASM_POWERPC_PPC4xx_H__
 
+#include <linux/types.h>
+
+/* GPIO */
+struct ppc4xx_gpio {
+	__be32 gpio_or;
+	__be32 gpio_tcr;
+	__be32 gpio_osrl;
+	__be32 gpio_osrh;
+	__be32 gpio_tsrl;
+	__be32 gpio_tsrh;
+	__be32 gpio_odr;
+	__be32 gpio_ir;
+	__be32 gpio_rr1;
+	__be32 gpio_rr2;
+	__be32 gpio_rr3;
+	__be32 reserved1;
+	__be32 gpio_isr1l;
+	__be32 gpio_isr1h;
+	__be32 gpio_isr2l;
+	__be32 gpio_isr2h;
+	__be32 gpio_isr3l;
+	__be32 gpio_isr3h;
+};
+
 extern void ppc4xx_reset_system(char *cmd);
 
 #endif /* __ASM_POWERPC_PPC4xx_H__ */
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..d401eba
--- /dev/null
+++ b/arch/powerpc/sysdev/ppc4xx_gpio.c
@@ -0,0 +1,239 @@ 
+/*
+ * PPC4xx gpio driver
+ *
+ * Copyright (c) 2008 Harris Corporation
+ * Copyright (c) 2008 Sascha Hauer <s.hauer@pengutronix.de>, Pengutronix
+ * Copyright (c) MontaVista Software, Inc. 2008.
+ *
+ * Author: Steve Falco <sfalco@harris.com>
+ *
+ * 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>
+
+#include <asm/ppc4xx.h>
+
+struct ppc4xx_gpio_chip {
+	struct of_mm_gpio_chip mm_gc;
+	spinlock_t lock;
+	u32 shadow_or;
+	u32 shadow_tcr;
+	u32 shadow_osrl;
+	u32 shadow_osrh;
+	u32 shadow_tsrl;
+	u32 shadow_tsrh;
+	u32 shadow_odr;
+};
+
+/*
+ * GPIO LIB API implementation for GPIOs
+ *
+ * There are a maximum of 64 gpios, spread over two sets of control registers.
+ * The sets are called GPIO0 and GPIO1.  Each set is managed separately, so
+ * there will be two entried in the .dts file.
+ */
+
+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;
+	u32 ret;
+
+	ret = (in_be32(&regs->gpio_ir) >> (31 - gpio)) & 1;
+
+	return ret;
+}
+
+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_chip *chip = to_ppc4xx_gpiochip(mm_gc);
+	struct ppc4xx_gpio __iomem *regs = mm_gc->regs;
+
+	if (val)
+		chip->shadow_or |= 1 << (31 - gpio);
+	else
+		chip->shadow_or &= ~(1 << (31 - gpio));
+	out_be32(&regs->gpio_or, chip->shadow_or);
+}
+
+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 */
+	chip->shadow_odr &= ~(1 << (31 - gpio));
+	out_be32(&regs->gpio_odr, chip->shadow_odr);
+
+	/* Float the pin */
+	chip->shadow_tcr &= ~(1 << (31 - gpio));
+	out_be32(&regs->gpio_tcr, chip->shadow_tcr);
+
+	/* Bits 0-15 use TSRL/OSRL, bits 16-31 use TSRH/OSRH */
+	if (gpio < 16) {
+		chip->shadow_osrl &= ~(3 << ((15 - gpio) * 2));
+		out_be32(&regs->gpio_osrl, chip->shadow_osrl);
+
+		chip->shadow_tsrl &= ~(3 << ((15 - gpio) * 2));
+		out_be32(&regs->gpio_tsrl, chip->shadow_tsrl);
+	} else {
+		chip->shadow_osrh &= ~(3 << ((31 - gpio) * 2));
+		out_be32(&regs->gpio_osrh, chip->shadow_osrh);
+
+		chip->shadow_tsrh &= ~(3 << ((31 - gpio) * 2));
+		out_be32(&regs->gpio_tsrh, chip->shadow_tsrh);
+	}
+
+	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 */
+	chip->shadow_odr &= ~(1 << (31 - gpio));
+	out_be32(&regs->gpio_odr, chip->shadow_odr);
+
+	/* Drive the pin */
+	chip->shadow_tcr |= (1 << (31 - gpio));
+	out_be32(&regs->gpio_tcr, chip->shadow_tcr);
+
+	/* Bits 0-15 use TSRL, bits 16-31 use TSRH */
+	if (gpio < 16) {
+		chip->shadow_osrl &= ~(3 << ((15 - gpio) * 2));
+		out_be32(&regs->gpio_osrl, chip->shadow_osrl);
+
+		chip->shadow_tsrl &= ~(3 << ((15 - gpio) * 2));
+		out_be32(&regs->gpio_tsrl, chip->shadow_tsrl);
+	} else {
+		chip->shadow_osrh &= ~(3 << ((31 - gpio) * 2));
+		out_be32(&regs->gpio_osrh, chip->shadow_osrh);
+
+		chip->shadow_tsrh &= ~(3 << ((31 - gpio) * 2));
+		out_be32(&regs->gpio_tsrh, chip->shadow_tsrh);
+	}
+
+	spin_unlock_irqrestore(&chip->lock, flags);
+
+	pr_debug("%s: gpio: %d val: %d\n", __func__, gpio, val);
+
+	return 0;
+}
+
+static void __init ppc4xx_gpio_save_regs(struct of_mm_gpio_chip *mm_gc)
+{
+	struct ppc4xx_gpio_chip *chip = to_ppc4xx_gpiochip(mm_gc);
+	struct ppc4xx_gpio __iomem *regs = mm_gc->regs;
+
+	chip->shadow_or = in_be32(&regs->gpio_or);
+	chip->shadow_tcr = in_be32(&regs->gpio_tcr);
+	chip->shadow_osrl = in_be32(&regs->gpio_osrl);
+	chip->shadow_osrh = in_be32(&regs->gpio_osrh);
+	chip->shadow_tsrl = in_be32(&regs->gpio_tsrl);
+	chip->shadow_tsrh = in_be32(&regs->gpio_tsrh);
+	chip->shadow_odr = in_be32(&regs->gpio_odr);
+}
+
+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;
+
+		mm_gc->save_regs = ppc4xx_gpio_save_regs;
+		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);