Re: [PATCH V2 4/6] tools/vhost-user-i2c: Add backend driver

[Jie Deng]

On 2021/4/1 20:12, Viresh Kumar wrote:
> +
> +/* vhost-user-i2c definitions */
> +
> +#define MAX_I2C_VDEV                    (1 << 7)
> +#define MAX_I2C_ADAPTER                 16

Generally speaking, 16 is big enough for most cases. But comparing with 
static configuration,
I think it is better if we can check how many adapters in the host when 
doing initialization and
use that number as "MAX_I2C_ADAPTER".


> +
> +static VI2cAdapter *vi2c_create_adapter(int32_t bus, uint16_t client_addr[],
> +                                        int32_t n_client)
> +{
> +    VI2cAdapter *adapter;
> +    char path[20];
> +    uint64_t funcs;
> +    int32_t fd, i;
> +
> +    if (bus < 0) {
> +        return NULL;
> +    }
> +
> +    adapter = g_malloc0(sizeof(*adapter));
> +    if (!adapter) {
> +        g_printerr("failed to alloc adapter");
> +        return NULL;
> +    }
> +
> +    snprintf(path, sizeof(path), "/dev/i2c-%d", bus);
> +    path[sizeof(path) - 1] = '\0';
> +
> +    fd = open(path, O_RDWR);
> +    if (fd < 0) {
> +        g_printerr("virtio_i2c: failed to open %s\n", path);
> +        goto fail;
> +    }
> +
> +    adapter->fd = fd;
> +    adapter->bus = bus;
> +
> +    if (ioctl(fd, I2C_FUNCS, &funcs) < 0) {
> +        g_printerr("virtio_i2c: failed to get functionality %s: %d\n", path,
> +                   errno);
> +        goto close_fd;
> +    }
> +
> +    if (funcs & I2C_FUNC_I2C) {
> +        adapter->smbus = false;
> +    } else if (funcs & I2C_FUNC_SMBUS_WORD_DATA) {


Only I2C_FUNC_SMBUS_WORD_DATA is checked here. But in addition to it, 
the smbus_xfer
seems support I2C_FUNC_SMBUS_BYTE, I2C_FUNC_SMBUS_BYTE_DATA. So if an 
adapter only
support the latter two, it will never go to smbus_xfer.



> +        adapter->smbus = true;
> +    } else {
> +        g_printerr("virtio_i2c: invalid functionality %lx\n", funcs);
> +        goto close_fd;
> +    }
> +