path: root/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/pm_runtime.h>
#include <linux/soundwire/sdw_registers.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)
{
	struct sdw_master_prop *prop = NULL;
	int ret;

	if (!bus->dev) {
		pr_err("SoundWire bus has no device");
		return -ENODEV;
	}

	if (!bus->ops) {
		dev_err(bus->dev, "SoundWire Bus ops are not set");
		return -EINVAL;
	}

	mutex_init(&bus->msg_lock);
	mutex_init(&bus->bus_lock);
	INIT_LIST_HEAD(&bus->slaves);
	INIT_LIST_HEAD(&bus->m_rt_list);

	if (bus->ops->read_prop) {
		ret = bus->ops->read_prop(bus);
		if (ret < 0) {
			dev_err(bus->dev, "Bus read properties failed:%d", ret);
			return ret;
		}
	}

	/*
	 * 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;
	}

	/*
	 * Initialize clock values based on Master properties. The max
	 * frequency is read from max_freq property. Current assumption
	 * is that the bus will start at highest clock frequency when
	 * powered on.
	 *
	 * Default active bank will be 0 as out of reset the Slaves have
	 * to start with bank 0 (Table 40 of Spec)
	 */
	prop = &bus->prop;
	bus->params.max_dr_freq = prop->max_freq * SDW_DOUBLE_RATE_FACTOR;
	bus->params.curr_dr_freq = bus->params.max_dr_freq;
	bus->params.curr_bank = SDW_BANK0;
	bus->params.next_bank = SDW_BANK1;

	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);

/*
 * SDW IO Calls
 */

static inline int find_response_code(enum sdw_command_response resp)
{
	switch (resp) {
	case SDW_CMD_OK:
		return 0;

	case SDW_CMD_IGNORED:
		return -ENODATA;

	case SDW_CMD_TIMEOUT:
		return -ETIMEDOUT;

	default:
		return -EIO;
	}
}

static inline int do_transfer(struct sdw_bus *bus, struct sdw_msg *msg)
{
	int retry = bus->prop.err_threshold;
	enum sdw_command_response resp;
	int ret = 0, i;

	for (i = 0; i <= retry; i++) {
		resp = bus->ops->xfer_msg(bus, msg);
		ret = find_response_code(resp);

		/* if cmd is ok or ignored return */
		if (ret == 0 || ret == -ENODATA)
			return ret;
	}

	return ret;
}

static inline int do_transfer_defer(struct sdw_bus *bus,
			struct sdw_msg *msg, struct sdw_defer *defer)
{
	int retry = bus->prop.err_threshold;
	enum sdw_command_response resp;
	int ret = 0, i;

	defer->msg = msg;
	defer->length = msg->len;

	for (i = 0; i <= retry; i++) {
		resp = bus->ops->xfer_msg_defer(bus, msg, defer);
		ret = find_response_code(resp);
		/* if cmd is ok or ignored return */
		if (ret == 0 || ret == -ENODATA)
			return ret;
	}

	return ret;
}

static int sdw_reset_page(struct sdw_bus *bus, u16 dev_num)
{
	int retry = bus->prop.err_threshold;
	enum sdw_command_response resp;
	int ret = 0, i;

	for (i = 0; i <= retry;