[PATCH RFC 02/12] power: sequencing: pcie-m2: implement port index matching

[Chen-Yu Tsai <wenst@chromium.org>]

For USB connections, the upstream USB (hub) device could be connected to
multiple M.2 E-key slots (or other power sequencer providers) via
different downstream USB ports. The provider needs a way to tell the
different connections apart so that the correct provider is matched.

In the previous change an index parameter was added for the consumer API
and the provider matching function. Implement port matching using the
index parameter. We simply check if the remote endpoint's port number
matches the index.

Signed-off-by: Chen-Yu Tsai <wenst@chromium.org>
---
 drivers/power/sequencing/pwrseq-pcie-m2.c | 22 +++++++++++++++++++---
 1 file changed, 19 insertions(+), 3 deletions(-)

diff --git a/drivers/power/sequencing/pwrseq-pcie-m2.c b/drivers/power/sequencing/pwrseq-pcie-m2.c
index 16a332f9da7d..c9aed2c02e81 100644
--- a/drivers/power/sequencing/pwrseq-pcie-m2.c
+++ b/drivers/power/sequencing/pwrseq-pcie-m2.c
@@ -165,12 +165,28 @@ static int pwrseq_pcie_m2_match(struct pwrseq_device *pwrseq,
 
 	/*
 	 * Traverse the 'remote-endpoint' nodes and check if the remote node's
-	 * parent matches the OF node of 'dev'.
+	 * parent matches the OF node of 'dev' and the port number matches
+	 * 'index'.
 	 */
 	for_each_endpoint_of_node(ctx->of_node, endpoint) {
+		struct device_node *remote_ep __free(device_node) =
+				of_graph_get_remote_endpoint(endpoint);
 		struct device_node *remote __free(device_node) =
-				of_graph_get_remote_port_parent(endpoint);
-		if (remote && (remote == dev_of_node(dev)))
+				of_graph_get_port_parent(remote_ep);
+		struct of_endpoint ep;
+
+		if (!remote)
+			continue;
+		if (remote != dev_of_node(dev))
+			continue;
+		/* For existing users of pwrseq_get(): index = -1 */
+		if (index < 0)
+			return PWRSEQ_MATCH_OK;
+
+		/* Check if the remote endpoint's port matches 'index'. */
+		if (of_graph_parse_endpoint(remote_ep, &ep) < 0)
+			continue;
+		if (ep.port == index)
 			return PWRSEQ_MATCH_OK;
 	}
 
-- 
2.54.0.563.g4f69b47b94-goog