[PATCH 1/4] soundwire: add enum to control device number allocation

[Bard Liao]

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

Commit c60561014257 ("soundwire: bus: allow device number to be unique
at system level") introduced two strategies to allocate device
numbers.

a) a default unconstrained allocation, where each bus can allocate
Device Numbers independently.

b) an ida-based allocation. In this case each Device Number will be
unique at the system-level.

The IDA-based allocation is useful to simplify debug, but it was also
introduced as a prerequisite to deal with the Intel Lunar Lake
hardware programming sequences: the wake-ups have to be handled with a
system-unique SDI address at the HDaudio controller level.

At the time, the restriction introduced by the IDA to 8 devices total
seemed perfectly fine, but recently hardware vendors created
configurations with more than 8 devices.

This patch provides an iso-functionality change, with the allocation
selected with an enum instead of an 'ida_min' value. Follow-up patches
will add a new allocation strategy to allow for more than 8 devices
using information on the type of devices, and only use the IDA-based
allocation for devices capable of generating a wake.

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             |  4 ++--
 drivers/soundwire/intel_auxdevice.c |  1 +
 include/linux/soundwire/sdw.h       | 16 +++++++++++++++-
 3 files changed, 18 insertions(+), 3 deletions(-)

diff --git a/drivers/soundwire/bus.c b/drivers/soundwire/bus.c
index b44f8d0affa6..e8c1c55a2a73 100644
--- a/drivers/soundwire/bus.c
+++ b/drivers/soundwire/bus.c
@@ -159,7 +159,7 @@ 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_ida_min)
+		if (bus->dev_num_alloc == SDW_DEV_NUM_ALLOC_IDA)
 			ida_free(&sdw_peripheral_ida, slave->dev_num);
 	}
 	list_del_init(&slave->node);
@@ -701,7 +701,7 @@ static int sdw_get_device_num(struct sdw_slave *slave)
 {
 	int bit;
 
-	if (slave->bus->dev_num_ida_min) {
+	if (slave->bus->dev_num_alloc == SDW_DEV_NUM_ALLOC_IDA) {
 		bit = ida_alloc_range(&sdw_peripheral_ida,
 				      slave->bus->dev_num_ida_min, SDW_MAX_DEVICES,
 				      GFP_KERNEL);
diff --git a/drivers/soundwire/intel_auxdevice.c b/drivers/soundwire/intel_auxdevice.c
index 0daa6ca9a224..30f3d2ab80fd 100644
--- a/drivers/soundwire/intel_auxdevice.c
+++ b/drivers/soundwire/intel_auxdevice.c
@@ -165,6 +165,7 @@ static int intel_link_probe(struct auxiliary_device *auxdev,
 	cdns->msg_count = 0;
 
 	bus->link_id = auxdev->id;
+	bus->dev_num_alloc = SDW_DEV_NUM_ALLOC_IDA;
 	bus->dev_num_ida_min = INTEL_DEV_NUM_IDA_MIN;
 	bus->clk_stop_timeout = 1;
 
diff --git a/include/linux/soundwire/sdw.h b/include/linux/soundwire/sdw.h
index c076a3f879b3..4656d6d0f3bb 100644
--- a/include/linux/soundwire/sdw.h
+++ b/include/linux/soundwire/sdw.h
@@ -864,6 +864,17 @@ struct sdw_master_ops {
 	void (*new_peripheral_assigned)(struct sdw_bus *bus, int dev_num);
 };
 
+/**
+ * enum sdw_dev_num_alloc - Device Number allocation strategies
+ * @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]
+ */
+enum sdw_dev_num_alloc {
+	SDW_DEV_NUM_ALLOC_DEFAULT = 0,
+	SDW_DEV_NUM_ALLOC_IDA,
+};
+
 /**
  * struct sdw_bus - SoundWire bus
  * @dev: Shortcut to &bus->md->dev to avoid changing the entire code.
@@ -895,9 +906,11 @@ struct sdw_master_ops {
  * meaningful if multi_link is set. If set to 1, hardware-based
  * synchronization will be used even if a stream only uses a single
  * SoundWire segment.
+ * @dev_num_alloc: bus-specific device number allocation
  * @dev_num_ida_min: if set, defines the minimum values for the IDA
  * used to allocate system-unique device numbers. This value needs to be
- * identical across all SoundWire bus in the system.
+ * identical across all SoundWire bus in the system. Only used if @sdw_num_alloc
+ * is not default.
  */
 struct sdw_bus {
 	struct device *dev;
@@ -922,6 +935,7 @@ struct sdw_bus {
 	u32 bank_switch_timeout;
 	bool multi_link;
 	int hw_sync_min_links;
+	enum sdw_dev_num_alloc dev_num_alloc;
 	int dev_num_ida_min;
 };
 
-- 
2.25.1