[PATCH v2] soundwire: stream: validate slave port properties

[Eric Wu <kunjinkao.jp@gmail.com>]

sdw_slave_port_config() validates that a port number is within the
generic valid range, but does not verify that the Slave exposes the
port for the requested stream direction. As a result, an in-range but
unsupported port, or a valid port used in the wrong direction, can be
accepted.

Use sdw_get_slave_dpn_prop() to perform the direction-specific lookup
and reject unsupported ports before storing the runtime configuration.

Signed-off-by: Eric Wu <kunjinkao.jp@gmail.com>
Reviewed-by: Charles Keepax <ckeepax@opensource.cirrus.com>
Reviewed-by: Bard Liao <yung-chuan.liao@linux.intel.com>
---
Changes in v2:
- Explain why the generic range check is insufficient.
- Perform a direction-specific DPN lookup and reject a missing entry.
- Drop the fallback that skipped validation when both port bitmaps were
  zero.

Testing:
- Locally compile-tested with GCC 9.4 using allmodconfig, W=1 and
  -Werror for x86_64, i386, arm64, arm and riscv64.
- SOF CI was temporarily unavailable. Bard Liao manually tested the
  patch on SoundWire hardware.

The same revision was reviewed and merged into the SOF topic/sof-dev
branch as commit 54c1da4:
https://github.com/thesofproject/linux/pull/5849#issuecomment-5141207403

 drivers/soundwire/stream.c | 17 +++++++++++++----
 1 file changed, 13 insertions(+), 4 deletions(-)

diff --git a/drivers/soundwire/stream.c b/drivers/soundwire/stream.c
index cbf7bd3d4e7b..e85025a5aea0 100644
--- a/drivers/soundwire/stream.c
+++ b/drivers/soundwire/stream.c
@@ -1069,14 +1069,23 @@ static int sdw_slave_port_config(struct sdw_slave *slave,
 
 	i = 0;
 	list_for_each_entry(p_rt, &s_rt->port_list, port_node) {
-		/*
-		 * TODO: Check valid port range as defined by DisCo/
-		 * slave
-		 */
 		if (!is_bpt_stream) {
 			ret = sdw_slave_port_is_valid_range(&slave->dev, port_config[i].num);
 			if (ret < 0)
 				return ret;
+
+			/*
+			 * A port in the generic valid range may still be unsupported by
+			 * the Slave or unavailable for the requested stream direction.
+			 */
+			if (!sdw_get_slave_dpn_prop(slave, s_rt->direction,
+						    port_config[i].num)) {
+				dev_err(&slave->dev,
+					"port %u not supported for %s\n",
+					port_config[i].num,
+					s_rt->direction == SDW_DATA_DIR_TX ? "TX" : "RX");
+				return -EINVAL;
+			}
 		} else if (port_config[i].num) {
 			return -EINVAL;
 		}
-- 
2.48.0