I’ve been working to get the access to the GPIO registers to replace the existing sys access we are using now. However, I’m crashing accessing both GPIO 2 and 3 (1 and 2 appear fine). I’m sure I’m just doing something stupid. Here is some basic setup:
`
__off_t MUX_OFFSET[] = {
0x44E07000, // GPIO 0
0x4804C000, // GPIO 1
0x481AC000, // GPIO 2
0x481AE000 // GPIO 3
};
struct MUX_LAYOUT
{
uint8_t *gpio_addr;
uint32_t *gpio_oe_addr;
uint32_t *gpio_setdataout_addr;
uint32_t *gpio_cleardataout_addr;
uint32_t *gpio_dataout_addr;
uint32_t *gpio_datain_addr;
};
MUX_LAYOUT MUXes[4];
#define GPIO_MEM_LENGTH 0xfff
#define GPIO_OE 0x134
#define GPIO_SETDATAOUT 0x194
#define GPIO_CLEARDATAOUT 0x190
#define GPIO_DATAOUT 0x13C
#define GPIO_DATAIN 0x138``
`
Then here is example code that will always crash on accessing GPIO 2:
`
fd = open("/dev/mem", O_RDWR);
for( size_t gpio = 0; gpio < 4; ++gpio)
{
MUX_LAYOUT& mux = MUXes[gpio];
mux.gpio_addr = (uint8_t*)mmap(0, GPIO_MEM_LENGTH, PROT_READ | PROT_WRITE, MAP_SHARED, fd, MUX_OFFSET[gpio]);
if(mux.gpio_addr == MAP_FAILED)
{
throw MSC_EXCEPTION(“Unable to map texpr PIO”);
}
mux.gpio_oe_addr = (uint32_t *)(mux.gpio_addr + GPIO_OE);
mux.gpio_setdataout_addr = (uint32_t *)(mux.gpio_addr + GPIO_SETDATAOUT);
mux.gpio_cleardataout_addr = (uint32_t *)(mux.gpio_addr + GPIO_CLEARDATAOUT);
mux.gpio_dataout_addr = (uint32_t *)(mux.gpio_addr + GPIO_DATAOUT);
mux.gpio_datain_addr = (uint32_t *)(mux.gpio_addr + GPIO_DATAIN);
// Crashes here when gpio == 2
uint32_t temp = *mux.gpio_datain_addr;
}
`
In this case I’m crashing dereferencing gpio_datain_addr, but it will crash accessing any of the pointers created when setting up GPIO 2 and 3. Any thoughts? I'm running a relatively current debian build.
Thanks for the help,
Jared
``