[alsa-devel] [PATCH v5 08/17] soundwire: add initial definitions for sdw_master_device

[Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>]

Since we want an explicit support for the SoundWire Master device, add
the definitions, following the Greybus example of a 'Host Device'.

A parent (such as the Intel audio controller) would use sdw_md_add()
to create the device, passing a driver as a parameter. The
sdw_md_release() would be called when put_device() is invoked by the
parent. We use the shortcut 'md' for 'master device' to avoid very
long function names.

The 'Master Device' driver exposes interfaces for
probe/startup/shutdown/remove and a placeholder for autonomous clock
stop support (when the bus control is handed over to a lower-power
solution, typically in D0ix modes).

Module namespace support is added in a separate patch.

Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
---
 drivers/soundwire/Makefile         |  2 +-
 drivers/soundwire/bus_type.c       |  5 ++-
 drivers/soundwire/master.c         | 63 ++++++++++++++++++++++++++++++
 include/linux/soundwire/sdw.h      | 38 ++++++++++++++++++
 include/linux/soundwire/sdw_type.h |  9 +++++
 5 files changed, 115 insertions(+), 2 deletions(-)
 create mode 100644 drivers/soundwire/master.c

diff --git a/drivers/soundwire/Makefile b/drivers/soundwire/Makefile
index 563894e5ecaf..89b29819dd3a 100644
--- a/drivers/soundwire/Makefile
+++ b/drivers/soundwire/Makefile
@@ -4,7 +4,7 @@
 #
 
 #Bus Objs
-soundwire-bus-objs := bus_type.o bus.o slave.o mipi_disco.o stream.o
+soundwire-bus-objs := bus_type.o bus.o master.o slave.o mipi_disco.o stream.o
 obj-$(CONFIG_SOUNDWIRE) += soundwire-bus.o
 
 ifdef CONFIG_DEBUG_FS
diff --git a/drivers/soundwire/bus_type.c b/drivers/soundwire/bus_type.c
index 605bc7ae57a8..2e4e8c2e629f 100644
--- a/drivers/soundwire/bus_type.c
+++ b/drivers/soundwire/bus_type.c
@@ -66,7 +66,10 @@ int sdw_uevent(struct device *dev, struct kobj_uevent_env *env)
 		 * callback is set to use this function for a
 		 * different device type (e.g. Master or Monitor)
 		 */
-		dev_err(dev, "uevent for unknown Soundwire type\n");
+		if (is_sdw_master_device(dev))
+			dev_err(dev, "uevent for SoundWire Master type\n");
+		else
+			dev_err(dev, "uevent for unknown Soundwire type\n");
 		return -EINVAL;
 	}
 
diff --git a/drivers/soundwire/master.c b/drivers/soundwire/master.c
new file mode 100644
index 000000000000..b018c561708e
--- /dev/null
+++ b/drivers/soundwire/master.c
@@ -0,0 +1,63 @@
+// SPDX-License-Identifier: (GPL-2.0)
+// Copyright(c) 2019 Intel Corporation.
+
+#include <linux/device.h>
+#include <linux/acpi.h>
+#include <linux/soundwire/sdw.h>
+#include <linux/soundwire/sdw_type.h>
+#include "bus.h"
+
+static void sdw_md_release(struct device *dev)
+{
+	struct sdw_master_device *md = to_sdw_master_device(dev);
+
+	kfree(md);
+}
+
+struct device_type sdw_md_type = {
+	.name =		"soundwire_master",
+	.release =	sdw_md_release,
+};
+
+struct sdw_master_device *sdw_md_add(struct sdw_md_driver *driver,
+				     struct device *parent,
+				     struct fwnode_handle *fwnode,
+				     int link_id)
+{
+	struct sdw_master_device *md;
+	int ret;
+
+	if (!driver->probe) {
+		dev_err(parent, "mandatory probe callback missing\n");
+		return ERR_PTR(-EINVAL);
+	}
+
+	md = kzalloc(sizeof(*md), GFP_KERNEL);
+	if (!md)
+		return ERR_PTR(-ENOMEM);
+
+	md->link_id = link_id;
+
+	md->driver = driver;
+
+	md->dev.parent = parent;
+	md->dev.fwnode = fwnode;
+	md->dev.bus = &sdw_bus_type;
+	md->dev.type = &sdw_md_type;
+	md->dev.dma_mask = md->dev.parent->dma_mask;
+	dev_set_name(&md->dev, "sdw-master-%d", md->link_id);
+
+	ret = device_register(&md->dev);
+	if (ret) {
+		dev_err(parent, "Failed to add master: ret %d\n", ret);
+		/*
+		 * On err, don't free but drop ref as this will be freed
+		 * when release method is invoked.
+		 */
+		put_device(&md->dev);
+		return ERR_PTR(-ENOMEM);
+	}
+
+	return md;
+}
+EXPORT_SYMBOL_GPL(sdw_md_add);
diff --git a/include/linux/soundwire/sdw.h b/include/linux/soundwire/sdw.h
index 5b1180f1e6b5..f73c355de5e5 100644
--- a/include/linux/soundwire/sdw.h
+++ b/include/linux/soundwire/sdw.h
@@ -585,6 +585,16 @@ struct sdw_slave {
 #define to_sdw_slave_device(d) \
 	container_of(d, struct sdw_slave, dev)
 
+struct sdw_master_device {
+	struct device dev;
+	int link_id;
+	struct sdw_md_driver *driver;
+	void *pdata;
+};
+
+#define to_sdw_master_device(d)	\
+	container_of(d, struct sdw_master_device, dev)
+
 struct sdw_driver {
 	const char *name;
 
@@ -599,6 +609,29 @@ struct sdw_driver {
 	struct device_driver driver;
 };
 
+/**
+ * struct sdw_md_driver - SoundWire 'Master Device' driver
+ *
+ * @probe: initializations and allocation (hardware may not be enabled yet)
+ * @startup: initialization handled after the hardware is enabled, all
+ * clock/power dependencies are available
+ * @shutdown: cleanups before hardware is disabled (optional)
+ * @free: free all remaining resources
+ * @autonomous_clock_stop_enable: enable/disable driver control while
+ * in clock-stop mode, typically in always-on/D0ix modes. When the driver
+ * yields control, another entity in the system (typically firmware
+ * running on an always-on microprocessor) is responsible to tracking
+ * Slave-initiated wakes
+ */
+struct sdw_md_driver {
+	int (*probe)(struct sdw_master_device *md, void *link_ctx);
+	int (*startup)(struct sdw_master_device *md);
+	int (*shutdown)(struct sdw_master_device *md);
+	int (*remove)(struct sdw_master_device *md);
+	int (*autonomous_clock_stop_enable)(struct sdw_master_device *md,
+					    bool state);
+};
+
 #define SDW_SLAVE_ENTRY(_mfg_id, _part_id, _drv_data) \
 	{ .mfg_id = (_mfg_id), .part_id = (_part_id), \
 	  .driver_data = (unsigned long)(_drv_data) }
@@ -788,6 +821,11 @@ struct sdw_bus {
 int sdw_add_bus_master(struct sdw_bus *bus);
 void sdw_delete_bus_master(struct sdw_bus *bus);
 
+struct sdw_master_device *sdw_md_add(struct sdw_md_driver *driver,
+				     struct device *parent,
+				     struct fwnode_handle *fwnode,
+				     int link_id);
+
 /**
  * sdw_port_config: Master or Slave Port configuration
  *
diff --git a/include/linux/soundwire/sdw_type.h b/include/linux/soundwire/sdw_type.h
index c681b3426478..a2a5ea7843a6 100644
--- a/include/linux/soundwire/sdw_type.h
+++ b/include/linux/soundwire/sdw_type.h
@@ -6,15 +6,24 @@
 
 extern struct bus_type sdw_bus_type;
 extern struct device_type sdw_slave_type;
+extern struct device_type sdw_md_type;
 
 static inline int is_sdw_slave(const struct device *dev)
 {
 	return dev->type == &sdw_slave_type;
 }
 
+static inline int is_sdw_master_device(const struct device *dev)
+{
+	return dev->type == &sdw_md_type;
+}
+
 #define to_sdw_slave_driver(_drv) \
 	container_of(_drv, struct sdw_driver, driver)
 
+#define to_sdw_md_driver(_drv) \
+	container_of(_drv, struct sdw_md_driver, driver)
+
 #define sdw_register_slave_driver(drv) \
 	__sdw_register_slave_driver(drv, THIS_MODULE)
 
-- 
2.20.1

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