static ssize_t state_read()

in slaves/w1_ds2413.c [27:79]

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

static ssize_t state_read(struct file *filp, struct kobject *kobj,
			  struct bin_attribute *bin_attr, char *buf, loff_t off,
			  size_t count)
{
	struct w1_slave *sl = kobj_to_w1_slave(kobj);
	unsigned int retries = W1_F3A_RETRIES;
	ssize_t bytes_read = -EIO;
	u8 state;

	dev_dbg(&sl->dev,
		"Reading %s kobj: %p, off: %0#10x, count: %zu, buff addr: %p",
		bin_attr->attr.name, kobj, (unsigned int)off, count, buf);

	if (off != 0)
		return 0;
	if (!buf)
		return -EINVAL;

	mutex_lock(&sl->master->bus_mutex);
	dev_dbg(&sl->dev, "mutex locked");

next:
	if (w1_reset_select_slave(sl))
		goto out;

	while (retries--) {
		w1_write_8(sl->master, W1_F3A_FUNC_PIO_ACCESS_READ);

		state = w1_read_8(sl->master);
		if ((state & 0x0F) == ((~state >> 4) & 0x0F)) {
			/* complement is correct */
			*buf = state;
			bytes_read = 1;
			goto out;
		} else if (state == W1_F3A_INVALID_PIO_STATE) {
			/* slave didn't respond, try to select it again */
			dev_warn(&sl->dev, "slave device did not respond to PIO_ACCESS_READ, " \
					    "reselecting, retries left: %d\n", retries);
			goto next;
		}

		if (w1_reset_resume_command(sl->master))
			goto out; /* unrecoverable error */

		dev_warn(&sl->dev, "PIO_ACCESS_READ error, retries left: %d\n", retries);
	}

out:
	mutex_unlock(&sl->master->bus_mutex);
	dev_dbg(&sl->dev, "%s, mutex unlocked, retries: %d\n",
		(bytes_read > 0) ? "succeeded" : "error", retries);
	return bytes_read;
}