p8_i2c_occ
struct p8_i2c_occ *ctx = to_p8_i2c_occ(occ);
struct p8_i2c_occ *ctx = devm_kzalloc(&client->dev, sizeof(*ctx),
#define to_p8_i2c_occ(x) container_of((x), struct p8_i2c_occ, occ)