static int read_scratchpad()

in slaves/w1_therm.c [1219:1271]

• 39 lines of code
• 8 McCabe index (conditional complexity)

static int read_scratchpad(struct w1_slave *sl, struct therm_info *info)
{
	struct w1_master *dev_master = sl->master;
	int max_trying = W1_THERM_MAX_TRY;
	int ret = -ENODEV;

	info->verdict = 0;

	if (!sl->family_data)
		goto error;

	memset(info->rom, 0, sizeof(info->rom));

	/* prevent the slave from going away in sleep */
	atomic_inc(THERM_REFCNT(sl->family_data));

	if (!bus_mutex_lock(&dev_master->bus_mutex)) {
		ret = -EAGAIN;	/* Didn't acquire the mutex */
		goto dec_refcnt;
	}

	while (max_trying-- && ret) { /* ret should be 0 */
		/* safe version to select slave */
		if (!reset_select_slave(sl)) {
			u8 nb_bytes_read;

			w1_write_8(dev_master, W1_READ_SCRATCHPAD);

			nb_bytes_read = w1_read_block(dev_master, info->rom, 9);
			if (nb_bytes_read != 9) {
				dev_warn(&sl->dev,
					"w1_read_block(): returned %u instead of 9.\n",
					nb_bytes_read);
				ret = -EIO;
			}

			info->crc = w1_calc_crc8(info->rom, 8);

			if (info->rom[8] == info->crc) {
				info->verdict = 1;
				ret = 0;
			} else
				ret = -EIO; /* CRC not checked */
		}

	}
	mutex_unlock(&dev_master->bus_mutex);

dec_refcnt:
	atomic_dec(THERM_REFCNT(sl->family_data));
error:
	return ret;
}