Device Mapping

device_map.c

#include <cstdio> // for printf debugging

struct port_channel
{
    unsigned int muxaddr;
    unsigned int muxchannel;
    unsigned int port_number;
};
typedef struct port_channel port_channel_t;

#define MUX_ADDR_1          0x74
#define MUX_ADDR_2          0x75
#define MUX_ADDR_3          0x76
#define MUX_ADDR_4          0x77

#define MUX_CHANNEL_0      0 // 0x01
#define MUX_CHANNEL_1      1 // 0x02
#define MUX_CHANNEL_2      2 // 0x04
#define MUX_CHANNEL_3      3 // 0x08
#define MUX_CHANNEL_4      4 // 0x10
#define MUX_CHANNEL_5      5 // 0x20
#define MUX_CHANNEL_6      6 // 0x40
#define MUX_CHANNEL_7      7 // 0x80

#define MAX_FRONT_PORT 64

/* This shouldn't happen unless there is an entry missing */
#define PORT_UNRECOGNISED  -2;
#define PORT_OUT_OF_BOUNDS -1;
#define PORT_OK             0;


port_channel_t port_channels[MAX_FRONT_PORT] =
{
    //1-8
    { MUX_ADDR_1, MUX_CHANNEL_0, 1 },
    { MUX_ADDR_1, MUX_CHANNEL_1, 2 },
    { MUX_ADDR_1, MUX_CHANNEL_2, 3 },
    { MUX_ADDR_1, MUX_CHANNEL_3, 4 },
    { MUX_ADDR_1, MUX_CHANNEL_4, 5 },
    { MUX_ADDR_1, MUX_CHANNEL_5, 6 },
    { MUX_ADDR_1, MUX_CHANNEL_6, 7 },
    { MUX_ADDR_1, MUX_CHANNEL_7, 8 },
    //9-16
    { MUX_ADDR_2, MUX_CHANNEL_0, 14 },
    { MUX_ADDR_2, MUX_CHANNEL_1, 13 },
    { MUX_ADDR_2, MUX_CHANNEL_2, 16 },
    { MUX_ADDR_2, MUX_CHANNEL_3, 15 },
    { MUX_ADDR_2, MUX_CHANNEL_4, 10 },
    { MUX_ADDR_2, MUX_CHANNEL_5,  9 },
    { MUX_ADDR_2, MUX_CHANNEL_6, 12 },
    { MUX_ADDR_2, MUX_CHANNEL_7, 11 },
    //17-24
    { MUX_ADDR_3, MUX_CHANNEL_0, 17 },
    { MUX_ADDR_3, MUX_CHANNEL_1, 18 },
    { MUX_ADDR_3, MUX_CHANNEL_2, 26 },
    { MUX_ADDR_3, MUX_CHANNEL_3, 25 },
    { MUX_ADDR_3, MUX_CHANNEL_4, 22 },
    { MUX_ADDR_3, MUX_CHANNEL_5, 21 },
    { MUX_ADDR_3, MUX_CHANNEL_6, 24 },
    { MUX_ADDR_3, MUX_CHANNEL_7, 23 },
    //25-32
    { MUX_ADDR_4, MUX_CHANNEL_0, 29 },
    { MUX_ADDR_4, MUX_CHANNEL_1, 30 },
    { MUX_ADDR_4, MUX_CHANNEL_2, 27 },
    { MUX_ADDR_4, MUX_CHANNEL_3, 28 },
    { MUX_ADDR_4, MUX_CHANNEL_4, 32 },
    { MUX_ADDR_4, MUX_CHANNEL_5, 31 },
    { MUX_ADDR_4, MUX_CHANNEL_6, 19 },
    { MUX_ADDR_4, MUX_CHANNEL_7, 20 },
    
    //33-40
    { MUX_ADDR_1, MUX_CHANNEL_0, 33 },
    { MUX_ADDR_1, MUX_CHANNEL_1, 34 },
    { MUX_ADDR_1, MUX_CHANNEL_2, 35 },
    { MUX_ADDR_1, MUX_CHANNEL_3, 36 },
    { MUX_ADDR_1, MUX_CHANNEL_4, 37 },
    { MUX_ADDR_1, MUX_CHANNEL_5, 38 },
    { MUX_ADDR_1, MUX_CHANNEL_6, 39 },
    { MUX_ADDR_1, MUX_CHANNEL_7, 40 },
    //41-48
    { MUX_ADDR_2, MUX_CHANNEL_0, 47 },
    { MUX_ADDR_2, MUX_CHANNEL_1, 48 },
    { MUX_ADDR_2, MUX_CHANNEL_2, 41 },
    { MUX_ADDR_2, MUX_CHANNEL_3, 42 },
    { MUX_ADDR_2, MUX_CHANNEL_4, 43 },
    { MUX_ADDR_2, MUX_CHANNEL_5, 44 },
    { MUX_ADDR_2, MUX_CHANNEL_6, 45 },
    { MUX_ADDR_2, MUX_CHANNEL_7, 46 },
    //49-56
    { MUX_ADDR_3, MUX_CHANNEL_0, 55 },
    { MUX_ADDR_3, MUX_CHANNEL_1, 56 },
    { MUX_ADDR_3, MUX_CHANNEL_2, 53 },
    { MUX_ADDR_3, MUX_CHANNEL_3, 54 },
    { MUX_ADDR_3, MUX_CHANNEL_4, 58 },
    { MUX_ADDR_3, MUX_CHANNEL_5, 57 },
    { MUX_ADDR_3, MUX_CHANNEL_6, 49 },
    { MUX_ADDR_3, MUX_CHANNEL_7, 50 },
    //57-64
    { MUX_ADDR_4, MUX_CHANNEL_0, 59 },
    { MUX_ADDR_4, MUX_CHANNEL_1, 60 },
    { MUX_ADDR_4, MUX_CHANNEL_2, 61 },
    { MUX_ADDR_4, MUX_CHANNEL_3, 62 },
    { MUX_ADDR_4, MUX_CHANNEL_4, 63 },
    { MUX_ADDR_4, MUX_CHANNEL_5, 64 },
    { MUX_ADDR_4, MUX_CHANNEL_6, 52 },
    { MUX_ADDR_4, MUX_CHANNEL_7, 51 }
};


int get_port_channel(unsigned int port, port_channel_t * device)
{
    if (port > MAX_FRONT_PORT)
    {
        return PORT_OUT_OF_BOUNDS;
    }
    for (int idx = 0ull; idx <= MAX_FRONT_PORT; ++idx)
    {
        if (port_channels[idx].port_number == port)
        {
            *device = port_channels[idx];
            return PORT_OK;
        }
    }
    return PORT_UNRECOGNISED;
}


int main() {
    /*  This seems to be a common pattern in C (declaration without
        initialisation) and as a C++ dev this irks me. Could add
        `= {0, 0, 0};` at the end. */
    port_channel_t device;
    int res = 0;

    for (int port = 0ull; port <= MAX_FRONT_PORT; ++port) {
        if ((res = get_port_channel(port, &device)) != 0)
        {
            printf("Could not find port %u [err: %d]\n", port, res);
            /*  You may just want to return -1; ONLP may not know how to deal
                with different return values -- this I don't really know 
                although given this would be called within onlp_i2c_mux_mapping
                it's entiry up to you. */
            return -1; // or res;
        }
        printf("Port: %u, mux address: 0x%02x, channel: %u\n", device.port_number,
            device.muxaddr, device.muxchannel);
    }
}

The idea is to replace the switch statement with a separate function. You would call this within onlp_i2c_mux_mapping.

You wouldn't use the loop in the function though, in case that's not clear! -- Just for printing results so you can check.