int tb_switch_tmu_post_time()

in tmu.c [236:327]

• 61 lines of code
• 14 McCabe index (conditional complexity)

int tb_switch_tmu_post_time(struct tb_switch *sw)
{
	unsigned int post_time_high_offset, post_time_high = 0;
	unsigned int post_local_time_offset, post_time_offset;
	struct tb_switch *root_switch = sw->tb->root_switch;
	u64 hi, mid, lo, local_time, post_time;
	int i, ret, retries = 100;
	u32 gm_local_time[3];

	if (!tb_route(sw))
		return 0;

	if (!tb_switch_is_usb4(sw))
		return 0;

	/* Need to be able to read the grand master time */
	if (!root_switch->tmu.cap)
		return 0;

	ret = tb_sw_read(root_switch, gm_local_time, TB_CFG_SWITCH,
			 root_switch->tmu.cap + TMU_RTR_CS_1,
			 ARRAY_SIZE(gm_local_time));
	if (ret)
		return ret;

	for (i = 0; i < ARRAY_SIZE(gm_local_time); i++)
		tb_sw_dbg(root_switch, "local_time[%d]=0x%08x\n", i,
			  gm_local_time[i]);

	/* Convert to nanoseconds (drop fractional part) */
	hi = gm_local_time[2] & TMU_RTR_CS_3_LOCAL_TIME_NS_MASK;
	mid = gm_local_time[1];
	lo = (gm_local_time[0] & TMU_RTR_CS_1_LOCAL_TIME_NS_MASK) >>
		TMU_RTR_CS_1_LOCAL_TIME_NS_SHIFT;
	local_time = hi << 48 | mid << 16 | lo;

	/* Tell the switch that time sync is disrupted for a while */
	ret = tb_switch_tmu_set_time_disruption(sw, true);
	if (ret)
		return ret;

	post_local_time_offset = sw->tmu.cap + TMU_RTR_CS_22;
	post_time_offset = sw->tmu.cap + TMU_RTR_CS_24;
	post_time_high_offset = sw->tmu.cap + TMU_RTR_CS_25;

	/*
	 * Write the Grandmaster time to the Post Local Time registers
	 * of the new switch.
	 */
	ret = tb_sw_write(sw, &local_time, TB_CFG_SWITCH,
			  post_local_time_offset, 2);
	if (ret)
		goto out;

	/*
	 * Have the new switch update its local time by:
	 * 1) writing 0x1 to the Post Time Low register and 0xffffffff to
	 * Post Time High register.
	 * 2) write 0 to Post Time High register and then wait for
	 * the completion of the post_time register becomes 0.
	 * This means the time has been converged properly.
	 */
	post_time = 0xffffffff00000001ULL;

	ret = tb_sw_write(sw, &post_time, TB_CFG_SWITCH, post_time_offset, 2);
	if (ret)
		goto out;

	ret = tb_sw_write(sw, &post_time_high, TB_CFG_SWITCH,
			  post_time_high_offset, 1);
	if (ret)
		goto out;

	do {
		usleep_range(5, 10);
		ret = tb_sw_read(sw, &post_time, TB_CFG_SWITCH,
				 post_time_offset, 2);
		if (ret)
			goto out;
	} while (--retries && post_time);

	if (!retries) {
		ret = -ETIMEDOUT;
		goto out;
	}

	tb_sw_dbg(sw, "TMU: updated local time to %#llx\n", local_time);

out:
	tb_switch_tmu_set_time_disruption(sw, false);
	return ret;
}