[PATCH 2/4] soundwire: introduce SDW_DEV_NUM_ALLOC_IDA_WAKE_ONLY

[Bard Liao]

From: Pierre-Louis Bossart <pierre-louis.bossart@xxxxxxxxxxxxxxx>

This patch adds a new Device Number allocation strategy, with the IDA
used only for devices that are wake-capable.

"regular" devices such as amplifiers will use Device Numbers
[1..min_ida-1].

"wake-capable" devices such as jack or microphone codecs will use
Device Numbers [min_ida..11].

This hybrid strategy extends the number of supported devices in a
system by only constraining the allocation if required, e.g. in the
case of Intel LunarLake platforms the wake-capable devices are
required to have a unique address to use the HDaudio SDI and HDAudio
WAKEEN/WAKESTS registers.

Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@xxxxxxxxxxxxxxx>
Reviewed-by: Rander Wang <rander.wang@xxxxxxxxx>
Signed-off-by: Bard Liao <yung-chuan.liao@xxxxxxxxxxxxxxx>
---
 drivers/soundwire/bus.c       | 26 +++++++++++++++++++++-----
 include/linux/soundwire/sdw.h |  4 ++++
 2 files changed, 25 insertions(+), 5 deletions(-)

diff --git a/drivers/soundwire/bus.c b/drivers/soundwire/bus.c
index e8c1c55a2a73..6f465cce8369 100644
--- a/drivers/soundwire/bus.c
+++ b/drivers/soundwire/bus.c
@@ -159,7 +159,9 @@ static int sdw_delete_slave(struct device *dev, void *data)
 
 	if (slave->dev_num) { /* clear dev_num if assigned */
 		clear_bit(slave->dev_num, bus->assigned);
-		if (bus->dev_num_alloc == SDW_DEV_NUM_ALLOC_IDA)
+		if (bus->dev_num_alloc == SDW_DEV_NUM_ALLOC_IDA ||
+		    (bus->dev_num_alloc == SDW_DEV_NUM_ALLOC_IDA_WAKE_ONLY &&
+		     slave->prop.wake_capable))
 			ida_free(&sdw_peripheral_ida, slave->dev_num);
 	}
 	list_del_init(&slave->node);
@@ -699,17 +701,31 @@ EXPORT_SYMBOL(sdw_compare_devid);
 /* called with bus_lock held */
 static int sdw_get_device_num(struct sdw_slave *slave)
 {
+	struct sdw_bus *bus = slave->bus;
 	int bit;
 
-	if (slave->bus->dev_num_alloc == SDW_DEV_NUM_ALLOC_IDA) {
+	if (bus->dev_num_alloc == SDW_DEV_NUM_ALLOC_IDA ||
+	    (bus->dev_num_alloc == SDW_DEV_NUM_ALLOC_IDA_WAKE_ONLY &&
+	     slave->prop.wake_capable)) {
 		bit = ida_alloc_range(&sdw_peripheral_ida,
-				      slave->bus->dev_num_ida_min, SDW_MAX_DEVICES,
+				      bus->dev_num_ida_min, SDW_MAX_DEVICES,
 				      GFP_KERNEL);
 		if (bit < 0)
 			goto err;
 	} else {
-		bit = find_first_zero_bit(slave->bus->assigned, SDW_MAX_DEVICES);
-		if (bit == SDW_MAX_DEVICES) {
+		int max_devices = SDW_MAX_DEVICES;
+
+		if (bus->dev_num_alloc == SDW_DEV_NUM_ALLOC_IDA_WAKE_ONLY &&
+		    !slave->prop.wake_capable) {
+			max_devices = bus->dev_num_ida_min - 1;
+
+			/* range check */
+			if (max_devices < 1 || max_devices > SDW_MAX_DEVICES)
+				return -EINVAL;
+		}
+
+		bit = find_first_zero_bit(bus->assigned, max_devices);
+		if (bit == max_devices) {
 			bit = -ENODEV;
 			goto err;
 		}
diff --git a/include/linux/soundwire/sdw.h b/include/linux/soundwire/sdw.h
index 4656d6d0f3bb..8a7541ac735e 100644
--- a/include/linux/soundwire/sdw.h
+++ b/include/linux/soundwire/sdw.h
@@ -869,10 +869,14 @@ struct sdw_master_ops {
  * @SDW_DEV_NUM_ALLOC_DEFAULT: unconstrained first-come-first-serve allocation,
  * using range [1, 11]
  * @SDW_DEV_NUM_ALLOC_IDA: IDA-based allocation, using range [ida_min, 11]
+ * @SDW_DEV_NUM_ALLOC_IDA_WAKE_ONLY: Hybrid allocation where wake-capable devices rely on
+ * IDA-based allocation and range [ida_min, 11], while regular devices rely on default
+ * allocation in range [1, ida_min - 1]
  */
 enum sdw_dev_num_alloc {
 	SDW_DEV_NUM_ALLOC_DEFAULT = 0,
 	SDW_DEV_NUM_ALLOC_IDA,
+	SDW_DEV_NUM_ALLOC_IDA_WAKE_ONLY,
 };
 
 /**
-- 
2.25.1