static blk_status_t gdrom_readdisk_dma()

in gdrom.c [571:633]

• 54 lines of code
• 9 McCabe index (conditional complexity)

static blk_status_t gdrom_readdisk_dma(struct request *req)
{
	int block, block_cnt;
	blk_status_t err;
	struct packet_command *read_command;
	unsigned long timeout;

	read_command = kzalloc(sizeof(struct packet_command), GFP_KERNEL);
	if (!read_command)
		return BLK_STS_RESOURCE;

	read_command->cmd[0] = 0x30;
	read_command->cmd[1] = 0x20;
	block = blk_rq_pos(req)/GD_TO_BLK + GD_SESSION_OFFSET;
	block_cnt = blk_rq_sectors(req)/GD_TO_BLK;
	__raw_writel(page_to_phys(bio_page(req->bio)) + bio_offset(req->bio),
			GDROM_DMA_STARTADDR_REG);
	__raw_writel(block_cnt * GDROM_HARD_SECTOR, GDROM_DMA_LENGTH_REG);
	__raw_writel(1, GDROM_DMA_DIRECTION_REG);
	__raw_writel(1, GDROM_DMA_ENABLE_REG);
	read_command->cmd[2] = (block >> 16) & 0xFF;
	read_command->cmd[3] = (block >> 8) & 0xFF;
	read_command->cmd[4] = block & 0xFF;
	read_command->cmd[8] = (block_cnt >> 16) & 0xFF;
	read_command->cmd[9] = (block_cnt >> 8) & 0xFF;
	read_command->cmd[10] = block_cnt & 0xFF;
	/* set for DMA */
	__raw_writeb(1, GDROM_ERROR_REG);
	/* other registers */
	__raw_writeb(0, GDROM_SECNUM_REG);
	__raw_writeb(0, GDROM_BCL_REG);
	__raw_writeb(0, GDROM_BCH_REG);
	__raw_writeb(0, GDROM_DSEL_REG);
	__raw_writeb(0, GDROM_INTSEC_REG);
	/* Wait for registers to reset after any previous activity */
	timeout = jiffies + HZ / 2;
	while (gdrom_is_busy() && time_before(jiffies, timeout))
		cpu_relax();
	__raw_writeb(GDROM_COM_PACKET, GDROM_STATUSCOMMAND_REG);
	timeout = jiffies + HZ / 2;
	/* Wait for packet command to finish */
	while (gdrom_is_busy() && time_before(jiffies, timeout))
		cpu_relax();
	gd.pending = 1;
	gd.transfer = 1;
	outsw(GDROM_DATA_REG, &read_command->cmd, 6);
	timeout = jiffies + HZ / 2;
	/* Wait for any pending DMA to finish */
	while (__raw_readb(GDROM_DMA_STATUS_REG) &&
		time_before(jiffies, timeout))
		cpu_relax();
	/* start transfer */
	__raw_writeb(1, GDROM_DMA_STATUS_REG);
	wait_event_interruptible_timeout(request_queue,
		gd.transfer == 0, GDROM_DEFAULT_TIMEOUT);
	err = gd.transfer ? BLK_STS_IOERR : BLK_STS_OK;
	gd.transfer = 0;
	gd.pending = 0;

	blk_mq_end_request(req, err);
	kfree(read_command);
	return BLK_STS_OK;
}