megapixels/device.c

#include "device.h"

#include <errno.h>
#include <fcntl.h>
#include <glib.h>
#include <stdio.h>
#include <string.h>
#include <sys/ioctl.h>
#include <unistd.h>

bool mp_find_device_path(struct media_v2_intf_devnode devnode, char *path, int length)
{
    char uevent_path[256];
    snprintf(uevent_path, 256, "/sys/dev/char/%d:%d/uevent", devnode.major, devnode.minor);

    FILE *f = fopen(uevent_path, "r");
    if (!f) {
        return false;
    }

    char line[512];
    while (fgets(line, 512, f)) {
        if (strncmp(line, "DEVNAME=", 8) == 0) {
            // Drop newline
            int length = strlen(line);
            if (line[length - 1] == '\n')
                line[length - 1] = '\0';

            snprintf(path, length, "/dev/%s", line + 8);
            return true;
        }
    }

    fclose(f);

    return false;
}

struct _MPDevice {
    int fd;

    struct media_device_info info;

    struct media_v2_entity *entities;
    size_t num_entities;
    struct media_v2_interface *interfaces;
    size_t num_interfaces;
    struct media_v2_pad *pads;
    size_t num_pads;
    struct media_v2_link *links;
    size_t num_links;
};

static void errno_printerr(const char *s)
{
    g_printerr("MPDevice: %s error %d, %s\n", s, errno, strerror(errno));
}

static int xioctl(int fd, int request, void *arg)
{
    int r;
    do {
        r = ioctl(fd, request, arg);
    } while (r == -1 && errno == EINTR);
    return r;
}

MPDevice *mp_device_find(const char *driver_name)
{
    MPDevice *found_device = NULL;

    int length = strlen(driver_name);
    MPDeviceList *list = mp_device_list_new();

    for (MPDeviceList *item = list; item; item = mp_device_list_next(item)) {
        MPDevice *device = mp_device_list_get(item);
        const struct media_device_info *info = mp_device_get_info(device);

        if (strncmp(info->driver, driver_name, length) == 0) {
            found_device = mp_device_list_remove(&item);
            break;
        }
    }

    mp_device_list_free(list);

    return found_device;
}

MPDevice *mp_device_open(const char *path)
{
    int fd = open(path, O_RDWR);
    if (fd == -1) {
        errno_printerr("open");
        return NULL;
    }

    return mp_device_new(fd);
}

MPDevice *mp_device_new(int fd)
{
    // Get the topology of the media device
    struct media_v2_topology topology = {};
    if (xioctl(fd, MEDIA_IOC_G_TOPOLOGY, &topology) == -1
        || topology.num_entities == 0) {
        close(fd);
        return NULL;
    }

    // Create the device
    MPDevice *device = calloc(1, sizeof(MPDevice));
    device->fd = fd;
    device->entities = calloc(topology.num_entities, sizeof(struct media_v2_entity));
    device->num_entities = topology.num_entities;
    device->interfaces = calloc(topology.num_interfaces, sizeof(struct media_v2_interface));
    device->num_interfaces = topology.num_interfaces;
    device->pads = calloc(topology.num_pads, sizeof(struct media_v2_pad));
    device->num_pads = topology.num_pads;
    device->links = calloc(topology.num_links, sizeof(struct media_v2_link));
    device->num_links = topology.num_links;

    // Get the actual devices and interfaces
    topology.ptr_entities = (uint64_t)device->entities;
    topology.ptr_interfaces = (uint64_t)device->interfaces;
    topology.ptr_pads = (uint64_t)device->pads;
    topology.ptr_links = (uint64_t)device->links;
    if (xioctl(fd, MEDIA_IOC_G_TOPOLOGY, &topology) == -1) {
        errno_printerr("MEDIA_IOC_G_TOPOLOGY");
        mp_device_close(device);
        return NULL;
    }

    // Get device info
    if (xioctl(fd, MEDIA_IOC_DEVICE_INFO, &device->info) == -1) {
        errno_printerr("MEDIA_IOC_DEVICE_INFO");
        mp_device_close(device);
        return NULL;
    }

    return device;
}

void mp_device_close(MPDevice *device)
{
    close(device->fd);
    free(device->entities);
    free(device->interfaces);
    free(device->pads);
    free(device->links);
    free(device);
}

bool mp_device_setup_link(MPDevice *device, uint32_t source_pad_id, uint32_t sink_pad_id, bool enabled)
{
    const struct media_v2_pad *source_pad = mp_device_get_pad(device, source_pad_id);
    g_return_val_if_fail(source_pad, false);

    const struct media_v2_pad *sink_pad = mp_device_get_pad(device, sink_pad_id);
    g_return_val_if_fail(sink_pad, false);

    struct media_link_desc link = {};
    link.flags = enabled ? MEDIA_LNK_FL_ENABLED : 0;
    link.source.entity = source_pad->entity_id;
    link.source.index = 0;
    link.sink.entity = sink_pad->entity_id;
    link.sink.index = 0;
    if (xioctl(device->fd, MEDIA_IOC_SETUP_LINK, &link) == -1) {
        errno_printerr("MEDIA_IOC_SETUP_LINK");
        return false;
    }

    return true;
}

const struct media_v2_entity *mp_device_find_entity(const MPDevice *device, const char *driver_name)
{
    int length = strlen(driver_name);

    // Find the entity from the name
    for (uint32_t i = 0; i < device->num_entities; ++i) {
        if (strncmp(device->entities[i].name, driver_name, length) == 0) {
            return &device->entities[i];
        }
    }
    return NULL;
}

const struct media_device_info *mp_device_get_info(const MPDevice *device)
{
    return &device->info;
}

const struct media_v2_entity *mp_device_get_entity(const MPDevice *device, uint32_t id)
{
    for (int i = 0; i < device->num_entities; ++i) {
        if (device->entities[i].id == id) {
            return &device->entities[i];
        }
    }
    return NULL;
}

const struct media_v2_entity *mp_device_get_entities(const MPDevice *device)
{
    return device->entities;
}

size_t mp_device_get_num_entities(const MPDevice *device)
{
    return device->num_entities;
}

const struct media_v2_interface *mp_device_find_entity_interface(const MPDevice *device, uint32_t entity_id)
{
    // Find the interface through the link
    const struct media_v2_link *link = mp_device_find_link_to(device, entity_id);
    if (!link) {
        return NULL;
    }
    return mp_device_get_interface(device, link->source_id);
}

const struct media_v2_interface *mp_device_get_interface(const MPDevice *device, uint32_t id)
{
    for (int i = 0; i < device->num_interfaces; ++i) {
        if (device->interfaces[i].id == id) {
            return &device->interfaces[i];
        }
    }
    return NULL;
}

const struct media_v2_interface *mp_device_get_interfaces(const MPDevice *device)
{
    return device->interfaces;
}

size_t mp_device_get_num_interfaces(const MPDevice *device)
{
    return device->num_interfaces;
}

const struct media_v2_pad *mp_device_get_pad_from_entity(const MPDevice *device, uint32_t entity_id)
{
    for (int i = 0; i < device->num_pads; ++i) {
        if (device->pads[i].entity_id == entity_id) {
            return &device->pads[i];
        }
    }
    return NULL;
}

const struct media_v2_pad *mp_device_get_pad(const MPDevice *device, uint32_t id)
{
    for (int i = 0; i < device->num_pads; ++i) {
        if (device->pads[i].id == id) {
            return &device->pads[i];
        }
    }
    return NULL;
}

const struct media_v2_pad *mp_device_get_pads(const MPDevice *device)
{
    return device->pads;
}

size_t mp_device_get_num_pads(const MPDevice *device)
{
    return device->num_pads;
}

const struct media_v2_link *mp_device_find_entity_link(const MPDevice *device, uint32_t entity_id)
{
    const struct media_v2_pad *pad = mp_device_get_pad_from_entity(device, entity_id);
    const struct media_v2_link *link = mp_device_find_link_to(device, pad->id);
    if (link) {
        return link;
    }
    return mp_device_find_link_from(device, pad->id);
}

const struct media_v2_link *mp_device_find_link_from(const MPDevice *device, uint32_t source)
{
    for (int i = 0; i < device->num_links; ++i) {
        if (device->links[i].source_id == source) {
            return &device->links[i];
        }
    }
    return NULL;
}

const struct media_v2_link *mp_device_find_link_to(const MPDevice *device, uint32_t sink)
{
    for (int i = 0; i < device->num_links; ++i) {
        if (device->links[i].sink_id == sink) {
            return &device->links[i];
        }
    }
    return NULL;
}

const struct media_v2_link *mp_device_find_link_between(const MPDevice *device, uint32_t source, uint32_t sink)
{
    for (int i = 0; i < device->num_links; ++i) {
        if (device->links[i].source_id == source
            && device->links[i].sink_id == sink) {
            return &device->links[i];
        }
    }
    return NULL;
}

const struct media_v2_link *mp_device_get_link(const MPDevice *device, uint32_t id)
{
    for (int i = 0; i < device->num_links; ++i) {
        if (device->links[i].id == id) {
            return &device->links[i];
        }
    }
    return NULL;
}

const struct media_v2_link *mp_device_get_links(const MPDevice *device)
{
    return device->links;
}

size_t mp_device_get_num_links(const MPDevice *device)
{
    return device->num_links;
}

struct _MPDeviceList {
    MPDevice *device;
    MPDeviceList *next;
};

MPDeviceList *mp_device_list_new()
{
    MPDeviceList *current = NULL;

    // Enumerate media device files
    struct dirent *dir;
    DIR *d = opendir("/dev");
    while ((dir = readdir(d)) != NULL) {
        if (strncmp(dir->d_name, "media", 5) == 0) {
            char path[261];
            snprintf(path, 261, "/dev/%s", dir->d_name);

            MPDevice *device = mp_device_open(path);

            if (device) {
                MPDeviceList *next = malloc(sizeof(MPDeviceList));
                next->device = device;
                next->next = current;
                current = next;
            }
        }
    }
    closedir(d);

    return current;
}

void mp_device_list_free(MPDeviceList *device_list)
{
    while (device_list) {
        MPDeviceList *tmp = device_list;
        device_list = tmp->next;

        mp_device_close(tmp->device);
        free(tmp);
    }
}

MPDevice *mp_device_list_remove(MPDeviceList **device_list)
{
    MPDevice *device = (*device_list)->device;

    if ((*device_list)->next) {
        MPDeviceList *tmp = (*device_list)->next;
        **device_list = *tmp;
        free(tmp);
    } else {
        free(*device_list);
        *device_list = NULL;
    }

    return device;
}

MPDevice *mp_device_list_get(const MPDeviceList *device_list)
{
    return device_list->device;
}

MPDeviceList *mp_device_list_next(const MPDeviceList *device_list)
{
    return device_list->next;
}