static int svc_i3c_master_do_daa_locked()

in master/svc-i3c-master.c [728:831]

• 65 lines of code
• 16 McCabe index (conditional complexity)

static int svc_i3c_master_do_daa_locked(struct svc_i3c_master *master,
					u8 *addrs, unsigned int *count)
{
	u64 prov_id[SVC_I3C_MAX_DEVS] = {}, nacking_prov_id = 0;
	unsigned int dev_nb = 0, last_addr = 0;
	u32 reg;
	int ret, i;

	while (true) {
		/* Enter/proceed with DAA */
		writel(SVC_I3C_MCTRL_REQUEST_PROC_DAA |
		       SVC_I3C_MCTRL_TYPE_I3C |
		       SVC_I3C_MCTRL_IBIRESP_NACK |
		       SVC_I3C_MCTRL_DIR(SVC_I3C_MCTRL_DIR_WRITE),
		       master->regs + SVC_I3C_MCTRL);

		/*
		 * Either one slave will send its ID, or the assignment process
		 * is done.
		 */
		ret = readl_poll_timeout_atomic(master->regs + SVC_I3C_MSTATUS,
						reg,
						SVC_I3C_MSTATUS_RXPEND(reg) |
						SVC_I3C_MSTATUS_MCTRLDONE(reg),
						1, 1000);
		if (ret)
			return ret;

		if (SVC_I3C_MSTATUS_RXPEND(reg)) {
			u8 data[6];

			/*
			 * We only care about the 48-bit provisional ID yet to
			 * be sure a device does not nack an address twice.
			 * Otherwise, we would just need to flush the RX FIFO.
			 */
			ret = svc_i3c_master_readb(master, data, 6);
			if (ret)
				return ret;

			for (i = 0; i < 6; i++)
				prov_id[dev_nb] |= (u64)(data[i]) << (8 * (5 - i));

			/* We do not care about the BCR and DCR yet */
			ret = svc_i3c_master_readb(master, data, 2);
			if (ret)
				return ret;
		} else if (SVC_I3C_MSTATUS_MCTRLDONE(reg)) {
			if (SVC_I3C_MSTATUS_STATE_IDLE(reg) &&
			    SVC_I3C_MSTATUS_COMPLETE(reg)) {
				/*
				 * All devices received and acked they dynamic
				 * address, this is the natural end of the DAA
				 * procedure.
				 */
				break;
			} else if (SVC_I3C_MSTATUS_NACKED(reg)) {
				/*
				 * A slave device nacked the address, this is
				 * allowed only once, DAA will be stopped and
				 * then resumed. The same device is supposed to
				 * answer again immediately and shall ack the
				 * address this time.
				 */
				if (prov_id[dev_nb] == nacking_prov_id)
					return -EIO;

				dev_nb--;
				nacking_prov_id = prov_id[dev_nb];
				svc_i3c_master_emit_stop(master);

				continue;
			} else {
				return -EIO;
			}
		}

		/* Wait for the slave to be ready to receive its address */
		ret = readl_poll_timeout_atomic(master->regs + SVC_I3C_MSTATUS,
						reg,
						SVC_I3C_MSTATUS_MCTRLDONE(reg) &&
						SVC_I3C_MSTATUS_STATE_DAA(reg) &&
						SVC_I3C_MSTATUS_BETWEEN(reg),
						0, 1000);
		if (ret)
			return ret;

		/* Give the slave device a suitable dynamic address */
		ret = i3c_master_get_free_addr(&master->base, last_addr + 1);
		if (ret < 0)
			return ret;

		addrs[dev_nb] = ret;
		dev_dbg(master->dev, "DAA: device %d assigned to 0x%02x\n",
			dev_nb, addrs[dev_nb]);

		writel(addrs[dev_nb], master->regs + SVC_I3C_MWDATAB);
		last_addr = addrs[dev_nb++];
	}

	*count = dev_nb;

	return 0;
}