memcpy_toio(target, cmd, sizeof(*cmd));
tail = (tail + sizeof(*cmd)) % iommu->cmd_buf_size;
head = readl(iommu->mmio_base + MMIO_CMD_HEAD_OFFSET);
memcpy_toio(target, cmd, sizeof(*cmd));
tail = (tail + sizeof(*cmd)) % iommu->cmd_buf_size;
head = readl(iommu->mmio_base + MMIO_CMD_HEAD_OFFSET);