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

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;
  

• }