[3.11.y.z extended stable] Patch "powerpc/gpio: Fix the wrong GPIO input data on MPC8572/MPC8536" has been added to staging queue

[Luis Henriques]

This is a note to let you know that I have just added a patch titled

    powerpc/gpio: Fix the wrong GPIO input data on MPC8572/MPC8536

to the linux-3.11.y-queue branch of the 3.11.y.z extended stable tree 
which can be found at:

 http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.11.y-queue

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.11.y.z tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Luis

------

>From f882a25271059153c441ea6d8e066245834319d5 Mon Sep 17 00:00:00 2001
From: Liu Gang <Gang.Liu at freescale.com>
Date: Fri, 22 Nov 2013 16:12:40 +0800
Subject: powerpc/gpio: Fix the wrong GPIO input data on MPC8572/MPC8536

commit 1aeef303b5d9e243c41d5b80f8bb059366514a10 upstream.

For MPC8572/MPC8536, the status of GPIOs defined as output
cannot be determined by reading GPDAT register, so the code
use shadow data register instead. But the code may give the
wrong status of GPIOs defined as input under some scenarios:

1. If some pins were configured as inputs and were asserted
high before booting the kernel, the shadow data has been
initialized with those pin values.
2. Some pins have been configured as output first and have
been set to the high value, then reconfigured as input.

The above cases will make the shadow data for those input
pins to be set to high. Then reading the pin status will
always return high even if the actual pin status is low.

The code should eliminate the effects of the shadow data to
the input pins, and the status of those pins should be
read directly from GPDAT.

Acked-by: Scott Wood <scottwood at freescale.com>
Acked-by: Anatolij Gustschin <agust at denx.de>
Signed-off-by: Liu Gang <Gang.Liu at freescale.com>
Signed-off-by: Linus Walleij <linus.walleij at linaro.org>
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
---
 drivers/gpio/gpio-mpc8xxx.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/drivers/gpio/gpio-mpc8xxx.c b/drivers/gpio/gpio-mpc8xxx.c
index a0b33a2..2aa3ca2 100644
--- a/drivers/gpio/gpio-mpc8xxx.c
+++ b/drivers/gpio/gpio-mpc8xxx.c
@@ -69,10 +69,14 @@ static int mpc8572_gpio_get(struct gpio_chip *gc, unsigned int gpio)
 	u32 val;
 	struct of_mm_gpio_chip *mm = to_of_mm_gpio_chip(gc);
 	struct mpc8xxx_gpio_chip *mpc8xxx_gc = to_mpc8xxx_gpio_chip(mm);
+	u32 out_mask, out_shadow;

-	val = in_be32(mm->regs + GPIO_DAT) & ~in_be32(mm->regs + GPIO_DIR);
+	out_mask = in_be32(mm->regs + GPIO_DIR);

-	return (val | mpc8xxx_gc->data) & mpc8xxx_gpio2mask(gpio);
+	val = in_be32(mm->regs + GPIO_DAT) & ~out_mask;
+	out_shadow = mpc8xxx_gc->data & out_mask;
+
+	return (val | out_shadow) & mpc8xxx_gpio2mask(gpio);
 }

 static int mpc8xxx_gpio_get(struct gpio_chip *gc, unsigned int gpio)
--
1.8.3.2