[U-Boot] [PATCH v2 1/2] bcm: Add GPIO driver

Stephen Warren
2012-07-31T15:52:18Z

On 07/31/2012 09:46 AM, Vikram Narayanan wrote:
> On 7/15/2012 10:53 PM, Stephen Warren wrote:
>> On 07/11/2012 02:37 PM, Vikram Narayanan wrote:
>>> Driver for BCM2835 SoC. This gives the basic functionality of
>>> setting/clearing the output.
>>
>>> diff --git a/arch/arm/include/asm/arch-bcm2835/gpio.h
>>> b/arch/arm/include/asm/arch-bcm2835/gpio.h

One more comment on the patch subject; it probably should be "gpio:
bcm2835:" not "bcm:" since (a) it's in the GPIO directory and (b) the
GPIO module is specifically for a BCM2835, and probably doesn't apply to
any/all Broadcom devices.

>>> diff --git a/drivers/gpio/Makefile b/drivers/gpio/Makefile
>>
>>> COBJS-$(CONFIG_DA8XX_GPIO) += da8xx_gpio.o
>>> COBJS-$(CONFIG_ALTERA_PIO) += altera_pio.o
>>> COBJS-$(CONFIG_MPC83XX_GPIO) += mpc83xx_gpio.o
>>> +COBJS-$(CONFIG_BCM2835_GPIO) += gpio_bcm2835.o
>>
>> It looks like the name bcm2835_gpio.c would be more consistent with
>> existing drivers, but not a big deal.
>>
>>> diff --git a/drivers/gpio/gpio_bcm2835.c b/drivers/gpio/gpio_bcm2835.c
>
> Linux kernel follows this naming, to be exact, it should've been
> gpio-bcm2835.c. Having a thought in mind that one day the namings would
> be made consistent with the kernel. That is the reason for this naming,
> but isn't a big deal to change it.

Hmmm. It seems better to be internally consistent with U-Boot rather
than keeping (onyl part of) U-Boot consistent with the kernel...

>> Shouldn't that be BCM2835_GPIO_COMMON_SHIFT not BCM2835_GPIO_COMMON_MASK?
>
> If you'd like to have naming consistency FSEL_SHIFT/COMMON_SHIFT, then
> it shall be COMMON_SHIFT.
>
> But it doesn't do any shifting like the FSEL_SHIFT, rather it does only
> masking of bits. So, it makes more sense for me to name it as MASK and
> not SHIFT.

The full quote you're replying to was:

>> +int gpio_get_value(unsigned gpio)
>
>> + return (val >> BCM2835_GPIO_COMMON_MASK(gpio)) & 0x1;
>
> Shouldn't that be BCM2835_GPIO_COMMON_SHIFT not BCM2835_GPIO_COMMON_MASK?

... so that macro is being used as a shift not as a mask.