static int sdw_program_device_num()

in bus.c [725:812]

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

static int sdw_program_device_num(struct sdw_bus *bus)
{
	u8 buf[SDW_NUM_DEV_ID_REGISTERS] = {0};
	struct sdw_slave *slave, *_s;
	struct sdw_slave_id id;
	struct sdw_msg msg;
	bool found;
	int count = 0, ret;
	u64 addr;

	/* No Slave, so use raw xfer api */
	ret = sdw_fill_msg(&msg, NULL, SDW_SCP_DEVID_0,
			   SDW_NUM_DEV_ID_REGISTERS, 0, SDW_MSG_FLAG_READ, buf);
	if (ret < 0)
		return ret;

	do {
		ret = sdw_transfer(bus, &msg);
		if (ret == -ENODATA) { /* end of device id reads */
			dev_dbg(bus->dev, "No more devices to enumerate\n");
			ret = 0;
			break;
		}
		if (ret < 0) {
			dev_err(bus->dev, "DEVID read fail:%d\n", ret);
			break;
		}

		/*
		 * Construct the addr and extract. Cast the higher shift
		 * bits to avoid truncation due to size limit.
		 */
		addr = buf[5] | (buf[4] << 8) | (buf[3] << 16) |
			((u64)buf[2] << 24) | ((u64)buf[1] << 32) |
			((u64)buf[0] << 40);

		sdw_extract_slave_id(bus, addr, &id);

		found = false;
		/* Now compare with entries */
		list_for_each_entry_safe(slave, _s, &bus->slaves, node) {
			if (sdw_compare_devid(slave, id) == 0) {
				found = true;

				/*
				 * Assign a new dev_num to this Slave and
				 * not mark it present. It will be marked
				 * present after it reports ATTACHED on new
				 * dev_num
				 */
				ret = sdw_assign_device_num(slave);
				if (ret < 0) {
					dev_err(bus->dev,
						"Assign dev_num failed:%d\n",
						ret);
					return ret;
				}

				break;
			}
		}

		if (!found) {
			/* TODO: Park this device in Group 13 */

			/*
			 * add Slave device even if there is no platform
			 * firmware description. There will be no driver probe
			 * but the user/integration will be able to see the
			 * device, enumeration status and device number in sysfs
			 */
			sdw_slave_add(bus, &id, NULL);

			dev_err(bus->dev, "Slave Entry not found\n");
		}

		count++;

		/*
		 * Check till error out or retry (count) exhausts.
		 * Device can drop off and rejoin during enumeration
		 * so count till twice the bound.
		 */

	} while (ret == 0 && count < (SDW_MAX_DEVICES * 2));

	return ret;
}