linux-kernel - [PATCH 2/2] soundwire: bus: Add internal slave ID and use for IRQs

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Message-Id: <20250422104245.958678-3-ckeepax@opensource.cirrus.com>
Date: Tue, 22 Apr 2025 11:42:45 +0100
From: Charles Keepax <ckeepax@...nsource.cirrus.com>
To: vkoul@...nel.org
Cc: yung-chuan.liao@...ux.intel.com, pierre-louis.bossart@...ux.dev,
        sanyog.r.kale@...el.com, linux-sound@...r.kernel.org,
        linux-kernel@...r.kernel.org, patches@...nsource.cirrus.com
Subject: [PATCH 2/2] soundwire: bus: Add internal slave ID and use for IRQs

Currently the SoundWire IRQ code uses the dev_num to create an IRQ
mapping for each slave. However, there is an issue there, the dev_num
is only allocated when the slave enumerates on the bus and enumeration
may happen before or after probe of the slave driver. In the case
enumeration happens after probe of the slave driver then the IRQ
mapping will use dev_num before it is set. This could cause multiple
slaves to use zero as their IRQ mapping.

It is very desirable to have the IRQ mapped before the slave probe
is called, so drivers can do resource allocation in probe as normal. To
solve these issues add an internal ID created for each slave when it is
probed and use that for mapping the IRQ. In the case that
get_device_num() is not implemented this ID can also be reused for the
dev_num.

Signed-off-by: Charles Keepax <ckeepax@...nsource.cirrus.com>
---
 drivers/soundwire/bus.c       |  8 +++-----
 drivers/soundwire/bus_type.c  | 13 +++++++++++++
 drivers/soundwire/irq.c       |  4 ++--
 include/linux/soundwire/sdw.h |  5 +++++
 4 files changed, 23 insertions(+), 7 deletions(-)

diff --git a/drivers/soundwire/bus.c b/drivers/soundwire/bus.c
index 3f1d8ff55022..f5fa92f3deae 100644
--- a/drivers/soundwire/bus.c
+++ b/drivers/soundwire/bus.c
@@ -56,6 +56,8 @@ int sdw_bus_master_add(struct sdw_bus *bus, struct device *parent,
 		return ret;
 	}
 
+	ida_init(&bus->slave_ida);
+
 	ret = sdw_master_device_add(bus, parent, fwnode);
 	if (ret < 0) {
 		dev_err(parent, "Failed to add master device at link %d\n",
@@ -731,11 +733,7 @@ static int sdw_get_device_num(struct sdw_slave *slave)
 		if (bit < 0)
 			goto err;
 	} else {
-		bit = find_first_zero_bit(bus->assigned, SDW_MAX_DEVICES);
-		if (bit == SDW_MAX_DEVICES) {
-			bit = -ENODEV;
-			goto err;
-		}
+		bit = slave->index;
 	}
 
 	/*
diff --git a/drivers/soundwire/bus_type.c b/drivers/soundwire/bus_type.c
index e98d5db81b1c..71aa307a5ac4 100644
--- a/drivers/soundwire/bus_type.c
+++ b/drivers/soundwire/bus_type.c
@@ -105,9 +105,19 @@ static int sdw_drv_probe(struct device *dev)
 	if (ret)
 		return ret;
 
+	ret = ida_alloc_range(&slave->bus->slave_ida, SDW_ENUM_DEV_NUM + 1,
+			      SDW_MAX_DEVICES, GFP_KERNEL);
+	if (ret < 0) {
+		dev_err(dev, "Failed to allocated ID: %d\n", ret);
+		return ret;
+	}
+	slave->index = ret;
+
 	ret = drv->probe(slave, id);
 	if (ret) {
 		dev_pm_domain_detach(dev, false);
+		ida_free(&slave->bus->slave_ida, slave->index);
+		slave->index = SDW_ENUM_DEV_NUM;
 		return ret;
 	}
 
@@ -174,6 +184,9 @@ static int sdw_drv_remove(struct device *dev)
 
 	dev_pm_domain_detach(dev, false);
 
+	ida_free(&slave->bus->slave_ida, slave->index);
+	slave->index = SDW_ENUM_DEV_NUM;
+
 	return ret;
 }
 
diff --git a/drivers/soundwire/irq.c b/drivers/soundwire/irq.c
index c237e6d0766b..98829290d134 100644
--- a/drivers/soundwire/irq.c
+++ b/drivers/soundwire/irq.c
@@ -50,12 +50,12 @@ static void sdw_irq_dispose_mapping(void *data)
 {
 	struct sdw_slave *slave = data;
 
-	irq_dispose_mapping(irq_find_mapping(slave->bus->domain, slave->dev_num));
+	irq_dispose_mapping(slave->irq);
 }
 
 void sdw_irq_create_mapping(struct sdw_slave *slave)
 {
-	slave->irq = irq_create_mapping(slave->bus->domain, slave->dev_num);
+	slave->irq = irq_create_mapping(slave->bus->domain, slave->index);
 	if (!slave->irq)
 		dev_warn(&slave->dev, "Failed to map IRQ\n");
 
diff --git a/include/linux/soundwire/sdw.h b/include/linux/soundwire/sdw.h
index 2362f621d94c..7dbbd38c66bd 100644
--- a/include/linux/soundwire/sdw.h
+++ b/include/linux/soundwire/sdw.h
@@ -8,6 +8,7 @@
 #include <linux/bug.h>
 #include <linux/completion.h>
 #include <linux/device.h>
+#include <linux/idr.h>
 #include <linux/irq.h>
 #include <linux/irqdomain.h>
 #include <linux/lockdep_types.h>
@@ -630,6 +631,7 @@ struct sdw_slave_ops {
  * struct sdw_slave - SoundWire Slave
  * @id: MIPI device ID
  * @dev: Linux device
+ * @index: internal ID for this slave
  * @irq: IRQ number
  * @status: Status reported by the Slave
  * @bus: Bus handle
@@ -661,6 +663,7 @@ struct sdw_slave_ops {
 struct sdw_slave {
 	struct sdw_slave_id id;
 	struct device dev;
+	int index;
 	int irq;
 	enum sdw_slave_status status;
 	struct sdw_bus *bus;
@@ -968,6 +971,7 @@ struct sdw_stream_runtime {
  * @md: Master device
  * @bus_lock_key: bus lock key associated to @bus_lock
  * @bus_lock: bus lock
+ * @slave_ida: IDA for allocating internal slave IDs
  * @slaves: list of Slaves on this bus
  * @msg_lock_key: message lock key associated to @msg_lock
  * @msg_lock: message lock
@@ -1010,6 +1014,7 @@ struct sdw_bus {
 	struct sdw_master_device *md;
 	struct lock_class_key bus_lock_key;
 	struct mutex bus_lock;
+	struct ida slave_ida;
 	struct list_head slaves;
 	struct lock_class_key msg_lock_key;
 	struct mutex msg_lock;
-- 
2.39.5