soundwire: Add Master registration

A Master adds a SoundWire bus instance which scans the firmware
provided for device description.

In this patch we scan ACPI namespaces and create SoundWire
Slave devices based on ACPI description

Signed-off-by: Sanyog Kale <[e-mail]>
Reviewed-by: Philippe Ombredanne <[e-mail]>
Acked-By: Pierre-Louis Bossart <[e-mail]>
Reviewed-by: Takashi Iwai <[e-mail]>
Acked-by: Greg Kroah-Hartman <[e-mail]>
Signed-off-by: Vinod Koul <[e-mail]>
Signed-off-by: Greg Kroah-Hartman <[e-mail]>

drivers/soundwire/Makefile

···
 #
 
 #Bus Objs
-soundwire-bus-objs := bus_type.o
+soundwire-bus-objs := bus_type.o bus.o slave.o
 obj-$(CONFIG_SOUNDWIRE_BUS) += soundwire-bus.o

drivers/soundwire/bus.c

···
+// SPDX-License-Identifier: (GPL-2.0 OR BSD-3-Clause)
+// Copyright(c) 2015-17 Intel Corporation.
+
+#include <linux/acpi.h>
+#include <linux/mod_devicetable.h>
+#include <linux/soundwire/sdw.h>
+#include "bus.h"
+
+/**
+ * sdw_add_bus_master() - add a bus Master instance
+ * @bus: bus instance
+ *
+ * Initializes the bus instance, read properties and create child
+ * devices.
+ */
+int sdw_add_bus_master(struct sdw_bus *bus)
+{
+	int ret;
+
+	if (!bus->dev) {
+		pr_err("SoundWire bus has no device");
+		return -ENODEV;
+	}
+
+	mutex_init(&bus->bus_lock);
+	INIT_LIST_HEAD(&bus->slaves);
+
+	/*
+	 * Device numbers in SoundWire are 0 thru 15. Enumeration device
+	 * number (0), Broadcast device number (15), Group numbers (12 and
+	 * 13) and Master device number (14) are not used for assignment so
+	 * mask these and other higher bits.
+	 */
+
+	/* Set higher order bits */
+	*bus->assigned = ~GENMASK(SDW_BROADCAST_DEV_NUM, SDW_ENUM_DEV_NUM);
+
+	/* Set enumuration device number and broadcast device number */
+	set_bit(SDW_ENUM_DEV_NUM, bus->assigned);
+	set_bit(SDW_BROADCAST_DEV_NUM, bus->assigned);
+
+	/* Set group device numbers and master device number */
+	set_bit(SDW_GROUP12_DEV_NUM, bus->assigned);
+	set_bit(SDW_GROUP13_DEV_NUM, bus->assigned);
+	set_bit(SDW_MASTER_DEV_NUM, bus->assigned);
+
+	/*
+	 * SDW is an enumerable bus, but devices can be powered off. So,
+	 * they won't be able to report as present.
+	 *
+	 * Create Slave devices based on Slaves described in
+	 * the respective firmware (ACPI/DT)
+	 */
+	if (IS_ENABLED(CONFIG_ACPI) && ACPI_HANDLE(bus->dev))
+		ret = sdw_acpi_find_slaves(bus);
+	else
+		ret = -ENOTSUPP; /* No ACPI/DT so error out */
+
+	if (ret) {
+		dev_err(bus->dev, "Finding slaves failed:%d\n", ret);
+		return ret;
+	}
+
+	return 0;
+}
+EXPORT_SYMBOL(sdw_add_bus_master);
+
+static int sdw_delete_slave(struct device *dev, void *data)
+{
+	struct sdw_slave *slave = dev_to_sdw_dev(dev);
+	struct sdw_bus *bus = slave->bus;
+
+	mutex_lock(&bus->bus_lock);
+
+	if (slave->dev_num) /* clear dev_num if assigned */
+		clear_bit(slave->dev_num, bus->assigned);
+
+	list_del_init(&slave->node);
+	mutex_unlock(&bus->bus_lock);
+
+	device_unregister(dev);
+	return 0;
+}
+
+/**
+ * sdw_delete_bus_master() - delete the bus master instance
+ * @bus: bus to be deleted
+ *
+ * Remove the instance, delete the child devices.
+ */
+void sdw_delete_bus_master(struct sdw_bus *bus)
+{
+	device_for_each_child(bus->dev, NULL, sdw_delete_slave);
+}
+EXPORT_SYMBOL(sdw_delete_bus_master);
+
+void sdw_extract_slave_id(struct sdw_bus *bus,
+			u64 addr, struct sdw_slave_id *id)
+{
+	dev_dbg(bus->dev, "SDW Slave Addr: %llx", addr);
+
+	/*
+	 * Spec definition
+	 *   Register		Bit	Contents
+	 *   DevId_0 [7:4]	47:44	sdw_version
+	 *   DevId_0 [3:0]	43:40	unique_id
+	 *   DevId_1		39:32	mfg_id [15:8]
+	 *   DevId_2		31:24	mfg_id [7:0]
+	 *   DevId_3		23:16	part_id [15:8]
+	 *   DevId_4		15:08	part_id [7:0]
+	 *   DevId_5		07:00	class_id
+	 */
+	id->sdw_version = (addr >> 44) & GENMASK(3, 0);
+	id->unique_id = (addr >> 40) & GENMASK(3, 0);
+	id->mfg_id = (addr >> 24) & GENMASK(15, 0);
+	id->part_id = (addr >> 8) & GENMASK(15, 0);
+	id->class_id = addr & GENMASK(7, 0);
+
+	dev_dbg(bus->dev,
+		"SDW Slave class_id %x, part_id %x, mfg_id %x, unique_id %x, version %x",
+				id->class_id, id->part_id, id->mfg_id,
+				id->unique_id, id->sdw_version);
+
+}

drivers/soundwire/bus.h

···
+// SPDX-License-Identifier: (GPL-2.0 OR BSD-3-Clause)
+// Copyright(c) 2015-17 Intel Corporation.
+
+#ifndef __SDW_BUS_H
+#define __SDW_BUS_H
+
+#if IS_ENABLED(CONFIG_ACPI)
+int sdw_acpi_find_slaves(struct sdw_bus *bus);
+#else
+static inline int sdw_acpi_find_slaves(struct sdw_bus *bus)
+{
+	return -ENOTSUPP;
+}
+#endif
+
+void sdw_extract_slave_id(struct sdw_bus *bus,
+			u64 addr, struct sdw_slave_id *id);
+
+#endif /* __SDW_BUS_H */

drivers/soundwire/slave.c

···
+// SPDX-License-Identifier: (GPL-2.0 OR BSD-3-Clause)
+// Copyright(c) 2015-17 Intel Corporation.
+
+#include <linux/acpi.h>
+#include <linux/soundwire/sdw.h>
+#include <linux/soundwire/sdw_type.h>
+#include "bus.h"
+
+static void sdw_slave_release(struct device *dev)
+{
+	struct sdw_slave *slave = dev_to_sdw_dev(dev);
+
+	kfree(slave);
+}
+
+static int sdw_slave_add(struct sdw_bus *bus,
+		struct sdw_slave_id *id, struct fwnode_handle *fwnode)
+{
+	struct sdw_slave *slave;
+	int ret;
+
+	slave = kzalloc(sizeof(*slave), GFP_KERNEL);
+	if (!slave)
+		return -ENOMEM;
+
+	/* Initialize data structure */
+	memcpy(&slave->id, id, sizeof(*id));
+	slave->dev.parent = bus->dev;
+	slave->dev.fwnode = fwnode;
+
+	/* name shall be sdw:link:mfg:part:class:unique */
+	dev_set_name(&slave->dev, "sdw:%x:%x:%x:%x:%x",
+			bus->link_id, id->mfg_id, id->part_id,
+			id->class_id, id->unique_id);
+
+	slave->dev.release = sdw_slave_release;
+	slave->dev.bus = &sdw_bus_type;
+	slave->bus = bus;
+	slave->status = SDW_SLAVE_UNATTACHED;
+	slave->dev_num = 0;
+
+	mutex_lock(&bus->bus_lock);
+	list_add_tail(&slave->node, &bus->slaves);
+	mutex_unlock(&bus->bus_lock);
+
+	ret = device_register(&slave->dev);
+	if (ret) {
+		dev_err(bus->dev, "Failed to add slave: ret %d\n", ret);
+
+		/*
+		 * On err, don't free but drop ref as this will be freed
+		 * when release method is invoked.
+		 */
+		mutex_lock(&bus->bus_lock);
+		list_del(&slave->node);
+		mutex_unlock(&bus->bus_lock);
+		put_device(&slave->dev);
+	}
+
+	return ret;
+}
+
+#if IS_ENABLED(CONFIG_ACPI)
+/*
+ * sdw_acpi_find_slaves() - Find Slave devices in Master ACPI node
+ * @bus: SDW bus instance
+ *
+ * Scans Master ACPI node for SDW child Slave devices and registers it.
+ */
+int sdw_acpi_find_slaves(struct sdw_bus *bus)
+{
+	struct acpi_device *adev, *parent;
+
+	parent = ACPI_COMPANION(bus->dev);
+	if (!parent) {
+		dev_err(bus->dev, "Can't find parent for acpi bind\n");
+		return -ENODEV;
+	}
+
+	list_for_each_entry(adev, &parent->children, node) {
+		unsigned long long addr;
+		struct sdw_slave_id id;
+		unsigned int link_id;
+		acpi_status status;
+
+		status = acpi_evaluate_integer(adev->handle,
+					METHOD_NAME__ADR, NULL, &addr);
+
+		if (ACPI_FAILURE(status)) {
+			dev_err(bus->dev, "_ADR resolution failed: %x\n",
+							status);
+			return status;
+		}
+
+		/* Extract link id from ADR, Bit 51 to 48 (included) */
+		link_id = (addr >> 48) & GENMASK(3, 0);
+
+		/* Check for link_id match */
+		if (link_id != bus->link_id)
+			continue;
+
+		sdw_extract_slave_id(bus, addr, &id);
+
+		/*
+		 * don't error check for sdw_slave_add as we want to continue
+		 * adding Slaves
+		 */
+		sdw_slave_add(bus, &id, acpi_fwnode_handle(adev));
+	}
+
+	return 0;
+}
+
+#endif

include/linux/soundwire/sdw.h

···
 struct sdw_bus;
 struct sdw_slave;
 
+/* SDW spec defines and enums, as defined by MIPI 1.1. Spec */
+
+/* SDW Broadcast Device Number */
+#define SDW_BROADCAST_DEV_NUM		15
+
+/* SDW Enumeration Device Number */
+#define SDW_ENUM_DEV_NUM		0
+
+/* SDW Group Device Numbers */
+#define SDW_GROUP12_DEV_NUM		12
+#define SDW_GROUP13_DEV_NUM		13
+
+/* SDW Master Device Number, not supported yet */
+#define SDW_MASTER_DEV_NUM		14
+
 #define SDW_MAX_DEVICES			11
 
 /**
···
 	DECLARE_BITMAP(assigned, SDW_MAX_DEVICES);
 	struct mutex bus_lock;
 };
+
+int sdw_add_bus_master(struct sdw_bus *bus);
+void sdw_delete_bus_master(struct sdw_bus *bus);
 
 #endif /* __SOUNDWIRE_H */