Commit d82e99a6 authored by Linus Walleij's avatar Linus Walleij Committed by Wolfram Sang

ARM: sa1100: simpad: Correct I2C GPIO offsets

Arnd reported the following build bug bug:

In file included from arch/arm/mach-sa1100/simpad.c:20:0:
arch/arm/mach-sa1100/include/mach/SA-1100.h:1118:18: error: large
integer implicitly truncated to unsigned type [-Werror=overflow]
                      (0x00000001 << (Nb))
include/linux/gpio/machine.h:56:16: note: in definition of macro
.chip_hwnum = _chip_hwnum,
arch/arm/mach-sa1100/include/mach/SA-1100.h:1140:21: note: in
expansion of macro 'GPIO_GPIO'
arch/arm/mach-sa1100/simpad.c:331:27: note: in expansion of
macro 'GPIO_GPIO21'

This is what happened:

commit b2e63555
"i2c: gpio: Convert to use descriptors"
commit 4d0ce62c
"i2c: gpio: Augment all boardfiles to use open drain"
together uncovered an old bug in the Simpad board
file: as theGPIO_LOOKUP_IDX() encodes GPIO offsets
on gpiochips in an u16 (see <linux/gpio/machine.h>)
these GPIO "numbers" does not fit, since in
arch/arm/mach-sa1100/include/mach/SA-1100.h it is
defined as:

  #define GPIO_GPIO(Nb) (0x00000001 << (Nb))
  #define GPIO_GPIO21 GPIO_GPIO(21) /* GPIO [21] */

This is however provably wrong, since the i2c-gpio
driver uses proper GPIO numbers, albeit earlier from
the global number space, whereas this GPIO_GPIO21
is the local line offset in the GPIO register, which
is used in other code but certainly not in the
gpiolib GPIO driver in drivers/gpio/gpio-sa1100.c, which
has code like this:

static void sa1100_gpio_set(struct gpio_chip *chip,
                            unsigned offset, int value)
    int reg = value ? R_GPSR : R_GPCR;

        sa1100_gpio_chip(chip)->membase + reg);

So far everything however compiled fine as an unsigned
int was used to pass the GPIO numbers in
struct i2c_gpio_platform_data. We can trace the actual error
back to

commit dbd406f9
"ARM: 7025/1: simpad: add GPIO based device definitions."
This added the i2c_gpio with the wrong offsets.

This commit was before the SA1100 was converted to use
the gpiolib, but as can be seen from the contemporary
gpio.c in mach-sa1100, it was already using:

static int sa1100_gpio_get(struct gpio_chip *chip,
                           unsigned offset)
        return GPLR & GPIO_GPIO(offset);

And GPIO_GPIO() is essentially the BIT() macro.
Reported-by: default avatarArnd Bergmann <>
Signed-off-by: default avatarLinus Walleij <>
Acked-by: default avatarArnd Bergmann <>
Signed-off-by: default avatarWolfram Sang <>
parent edd20e95
......@@ -327,9 +327,9 @@ static struct platform_device simpad_gpio_leds = {
static struct gpiod_lookup_table simpad_i2c_gpiod_table = {
.dev_id = "i2c-gpio",
.table = {
GPIO_LOOKUP_IDX("gpio", 21, NULL, 0,
GPIO_LOOKUP_IDX("gpio", 25, NULL, 1,
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