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
+#define BCM2835_GPIO_BASE 0x7E200000 +#define BCM2835_NUM_GPIOS 53
For consistency, that might be better as BCM2835_GPIO_COUNT, but not a big deal.
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
+inline int gpio_is_valid(unsigned gpio) +{
- return (gpio > BCM2835_NUM_GPIOS) ? 0 : 1;
Presumably gpio==0 is a valid GPIO, so that should be >= not >. It'd be simpler to write it as:
return gpio < BCM2835_NUM_GPIOS;
+int gpio_request(unsigned gpio, const char *label) +{
- return (gpio_is_valid(gpio)) ? 1 : 0;
Why not just return gpio_is_valid_(gpio) directly?
+int gpio_direction_input(unsigned gpio)
- val = readl(®->gpfsel[BCM2835_GPIO_FSEL_BANK(gpio)]);
- val &= ~(BCM2835_GPIO_FSEL_MASK << BCM2835_GPIO_FSEL_SHIFT(gpio));
Even if BCM2835_GPIO_OUTPUT==0, it seems better to | it in here for documentation purposes, so add:
val |= (BCM2835_GPIO_INPUT << BCM2835_GPIO_FSEL_SHIFT(gpio));
Otherwise, there's not much point creating the #define BCM2835_GPIO_INPUT.
+int gpio_direction_output(unsigned gpio, int value) +{
- struct bcm_gpio_regs *reg = (struct bcm_gpio_regs *)BCM2835_GPIO_BASE;
- unsigned val;
- val = readl(®->gpfsel[BCM2835_GPIO_FSEL_BANK(gpio)]);
- val &= ~(BCM2835_GPIO_FSEL_MASK << BCM2835_GPIO_FSEL_SHIFT(gpio));
- val |= (BCM2835_GPIO_OUTPUT << BCM2835_GPIO_FSEL_SHIFT(gpio));
- writel(val, reg->gpfsel[BCM2835_GPIO_FSEL_BANK(gpio)]);
This (setting the direction) should happen after the following to set the value:
- if (value)
gpio_set_value(gpio, value);
That way, when the GPIO is set to output, the correct value will immediately be driven onto the GPIO, so a glitch may be avoided.
+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?
+int gpio_set_value(unsigned gpio, int value) +{
- struct bcm_gpio_regs *reg = (struct bcm_gpio_regs *)BCM2835_GPIO_BASE;
- u32 *output_reg = value ? reg->gpset : reg->gpclr;
- writel(1 << BCM2835_GPIO_COMMON_MASK(gpio),
output_reg[BCM2835_GPIO_COMMON_BANK(gpio)]);
Same comment here.