soundwire: bus: Allow SoundWire peripherals to register IRQ handlers

Currently the in-band alerts for SoundWire peripherals can only
be communicated to the driver through the interrupt_callback
function. This however is slightly inconvenient for devices that wish
to share IRQ handling code between SoundWire and I2C/SPI, the later
would normally register an IRQ handler with the IRQ subsystem. However
there is no reason the SoundWire in-band IRQs can not also be
communicated as an actual IRQ to the driver.

Add support for SoundWire peripherals to register a normal IRQ
handler to receive SoundWire in-band alerts, allowing code to be
shared across control buses. Note that we allow users to use both the
interrupt_callback and the IRQ handler, this is useful for devices
which must clear additional chip specific SoundWire registers that are
not a part of the normal IRQ flow, or the SoundWire specification.

Signed-off-by: Lucas Tanure <tanureal@opensource.cirrus.com>
Reviewed-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Acked-by: Bard Liao <yung-chuan.liao@linux.intel.com>
Acked-by: Vinod Koul <vkoul@kernel.org>
Signed-off-by: Charles Keepax <ckeepax@opensource.cirrus.com>
Link: https://lore.kernel.org/r/20230804104602.395892-2-ckeepax@opensource.cirrus.com
Signed-off-by: Lee Jones <lee@kernel.org>

2 files changed, 44 insertions, 0 deletions

diff --git a/drivers/soundwire/bus.c b/drivers/soundwire/bus.c
index dba920ec88f6..cf55386256f3 100644
--- a/drivers/soundwire/bus.c
+++ b/drivers/soundwire/bus.c
@@ -3,6 +3,7 @@
 
 #include <linux/acpi.h>
 #include <linux/delay.h>
+#include <linux/irq.h>
 #include <linux/mod_devicetable.h>
 #include <linux/pm_runtime.h>
 #include <linux/soundwire/sdw_registers.h>
@@ -25,6 +26,23 @@ static int sdw_get_id(struct sdw_bus *bus)
 	return 0;
 }
 
+static int sdw_irq_map(struct irq_domain *h, unsigned int virq,
+		       irq_hw_number_t hw)
+{
+	struct sdw_bus *bus = h->host_data;
+
+	irq_set_chip_data(virq, bus);
+	irq_set_chip(virq, &bus->irq_chip);
+	irq_set_nested_thread(virq, 1);
+	irq_set_noprobe(virq);
+
+	return 0;
+}
+
+static const struct irq_domain_ops sdw_domain_ops = {
+	.map	= sdw_irq_map,
+};
+
 /**
  * sdw_bus_master_add() - add a bus Master instance
  * @bus: bus instance
@@ -151,6 +169,14 @@ int sdw_bus_master_add(struct sdw_bus *bus, struct device *parent,
 	bus->params.curr_bank = SDW_BANK0;
 	bus->params.next_bank = SDW_BANK1;
 
+	bus->irq_chip.name = dev_name(bus->dev);
+	bus->domain = irq_domain_create_linear(fwnode, SDW_MAX_DEVICES,
+					       &sdw_domain_ops, bus);
+	if (!bus->domain) {
+		dev_err(bus->dev, "Failed to add IRQ domain\n");
+		return -EINVAL;
+	}
+
 	return 0;
 }
 EXPORT_SYMBOL(sdw_bus_master_add);
@@ -187,6 +213,9 @@ static int sdw_delete_slave(struct device *dev, void *data)
 void sdw_bus_master_delete(struct sdw_bus *bus)
 {
 	device_for_each_child(bus->dev, NULL, sdw_delete_slave);
+
+	irq_domain_remove(bus->domain);
+
 	sdw_master_device_del(bus);
 
 	sdw_bus_debugfs_exit(bus);
@@ -1725,6 +1754,9 @@ static int sdw_handle_slave_alerts(struct sdw_slave *slave)
 				struct device *dev = &slave->dev;
 				struct sdw_driver *drv = drv_to_sdw_driver(dev->driver);
 
+				if (slave->prop.use_domain_irq && slave->irq)
+					handle_nested_irq(slave->irq);
+
 				if (drv->ops && drv->ops->interrupt_callback) {
 					slave_intr.sdca_cascade = sdca_cascade;
 					slave_intr.control_port = clear;
diff --git a/drivers/soundwire/bus_type.c b/drivers/soundwire/bus_type.c
index 1f43ee848eac..fafbc284e82d 100644
--- a/drivers/soundwire/bus_type.c
+++ b/drivers/soundwire/bus_type.c
@@ -122,6 +122,12 @@ static int sdw_drv_probe(struct device *dev)
 	if (drv->ops && drv->ops->read_prop)
 		drv->ops->read_prop(slave);
 
+	if (slave->prop.use_domain_irq) {
+		slave->irq = irq_create_mapping(slave->bus->domain, slave->dev_num);
+		if (!slave->irq)
+			dev_warn(dev, "Failed to map IRQ\n");
+	}
+
 	/* init the sysfs as we have properties now */
 	ret = sdw_slave_sysfs_init(slave);
 	if (ret < 0)
@@ -166,7 +172,13 @@ static int sdw_drv_remove(struct device *dev)
 	int ret = 0;
 
 	mutex_lock(&slave->sdw_dev_lock);
+
 	slave->probed = false;
+
+	if (slave->prop.use_domain_irq)
+		irq_dispose_mapping(irq_find_mapping(slave->bus->domain,
+						     slave->dev_num));
+
 	mutex_unlock(&slave->sdw_dev_lock);
 
 	if (drv->remove)