src/kernel/linux/v4.19/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