74 lines
2.6 KiB
C
Executable File
74 lines
2.6 KiB
C
Executable File
// Copyright (c) 2014 Adafruit Industries
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// Author: Tony DiCola
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// Permission is hereby granted, free of charge, to any person obtaining a copy
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// of this software and associated documentation files (the "Software"), to deal
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// in the Software without restriction, including without limitation the rights
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// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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// copies of the Software, and to permit persons to whom the Software is
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// furnished to do so, subject to the following conditions:
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// The above copyright notice and this permission notice shall be included in all
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// copies or substantial portions of the Software.
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// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
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// SOFTWARE.
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#include <fcntl.h>
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#include <stdlib.h>
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#include <string.h>
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#include <sys/mman.h>
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#include <sys/stat.h>
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#include <sys/types.h>
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#include "bbb_mmio.h"
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#define GPIO_LENGTH 4096
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#define GPIO0_ADDR 0x44E07000
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#define GPIO1_ADDR 0x4804C000
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#define GPIO2_ADDR 0x481AC000
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#define GPIO3_ADDR 0x481AF000
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// Store mapping of GPIO base number to GPIO address.
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static uint32_t gpio_addresses[4] = { GPIO0_ADDR, GPIO1_ADDR, GPIO2_ADDR, GPIO3_ADDR };
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// Cache memory-mapped GPIO addresses.
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static volatile uint32_t* gpio_base[4] = { NULL };
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int bbb_mmio_get_gpio(int base, int number, gpio_t* gpio) {
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// Validate input parameters.
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if (gpio == NULL) {
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return MMIO_ERROR_ARGUMENT;
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}
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if (base < 0 || base > 3) {
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return MMIO_ERROR_ARGUMENT;
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}
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if (number < 0 || number > 31) {
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return MMIO_ERROR_ARGUMENT;
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}
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// Map GPIO memory if its hasn't been mapped already.
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if (gpio_base[base] == NULL) {
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int fd = open("/dev/mem", O_RDWR | O_SYNC);
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if (fd == -1) {
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// Error opening /dev/mem. Probably not running as root.
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return MMIO_ERROR_DEVMEM;
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}
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// Map GPIO memory to location in process space.
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gpio_base[base] = (uint32_t*)mmap(NULL, GPIO_LENGTH, PROT_READ | PROT_WRITE, MAP_SHARED, fd, gpio_addresses[base]);
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if (gpio_base[base] == MAP_FAILED) {
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// Don't save the result if the memory mapping failed.
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gpio_base[base] = NULL;
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return MMIO_ERROR_MMAP;
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}
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}
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// Initialize and set GPIO fields.
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memset(gpio, 0, sizeof(gpio));
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gpio->base = gpio_base[base];
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gpio->number = number;
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return MMIO_SUCCESS;
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}
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