drivers/hsi/hsi_core.c - linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0-only
 /*
  * HSI core.
  *
  * Copyright (C) 2010 Nokia Corporation. All rights reserved.
  *
  * Contact: Carlos Chinea <carlos.chinea@nokia.com>
  */
 #include <linux/hsi/hsi.h>
 #include <linux/compiler.h>
 #include <linux/list.h>
 #include <linux/kobject.h>
 #include <linux/slab.h>
 #include <linux/string.h>
 #include <linux/notifier.h>
 #include <linux/of.h>
 #include <linux/of_device.h>
 #include "hsi_core.h"

 static ssize_t modalias_show(struct device *dev,
 			struct device_attribute *a __maybe_unused, char *buf)
 {
 	return sprintf(buf, "hsi:%s\n", dev_name(dev));
 }
 static DEVICE_ATTR_RO(modalias);

 static struct attribute *hsi_bus_dev_attrs[] = {
 	&dev_attr_modalias.attr,
 	NULL,
 };
 ATTRIBUTE_GROUPS(hsi_bus_dev);

 static int hsi_bus_uevent(const struct device *dev, struct kobj_uevent_env *env)
 {
 	add_uevent_var(env, "MODALIAS=hsi:%s", dev_name(dev));

 	return 0;
 }

 static int hsi_bus_match(struct device *dev, struct device_driver *driver)
 {
 	if (of_driver_match_device(dev, driver))
 		return true;

 	if (strcmp(dev_name(dev), driver->name) == 0)
 		return true;

 	return false;
 }

 static struct bus_type hsi_bus_type = {
 	.name		= "hsi",
 	.dev_groups	= hsi_bus_dev_groups,
 	.match		= hsi_bus_match,
 	.uevent		= hsi_bus_uevent,
 };

 static void hsi_client_release(struct device *dev)
 {
 	struct hsi_client *cl = to_hsi_client(dev);

 	kfree(cl->tx_cfg.channels);
 	kfree(cl->rx_cfg.channels);
 	kfree(cl);
 }

 struct hsi_client *hsi_new_client(struct hsi_port *port,
 						struct hsi_board_info *info)
 {
 	struct hsi_client *cl;
 	size_t size;

 	cl = kzalloc(sizeof(*cl), GFP_KERNEL);
 	if (!cl)
 		goto err;

 	cl->tx_cfg = info->tx_cfg;
 	if (cl->tx_cfg.channels) {
 		size = cl->tx_cfg.num_channels * sizeof(*cl->tx_cfg.channels);
 		cl->tx_cfg.channels = kmemdup(info->tx_cfg.channels, size,
 					      GFP_KERNEL);
 		if (!cl->tx_cfg.channels)
 			goto err_tx;
 	}

 	cl->rx_cfg = info->rx_cfg;
 	if (cl->rx_cfg.channels) {
 		size = cl->rx_cfg.num_channels * sizeof(*cl->rx_cfg.channels);
 		cl->rx_cfg.channels = kmemdup(info->rx_cfg.channels, size,
 					      GFP_KERNEL);
 		if (!cl->rx_cfg.channels)
 			goto err_rx;
 	}

 	cl->device.bus = &hsi_bus_type;
 	cl->device.parent = &port->device;
 	cl->device.release = hsi_client_release;
 	dev_set_name(&cl->device, "%s", info->name);
 	cl->device.platform_data = info->platform_data;
 	if (info->archdata)
 		cl->device.archdata = *info->archdata;
 	if (device_register(&cl->device) < 0) {
 		pr_err("hsi: failed to register client: %s\n", info->name);
 		put_device(&cl->device);
 		goto err;
 	}

 	return cl;
 err_rx:
 	kfree(cl->tx_cfg.channels);
 err_tx:
 	kfree(cl);
 err:
 	return NULL;
 }
 EXPORT_SYMBOL_GPL(hsi_new_client);

 static void hsi_scan_board_info(struct hsi_controller *hsi)
 {
 	struct hsi_cl_info *cl_info;
 	struct hsi_port	*p;

 	list_for_each_entry(cl_info, &hsi_board_list, list)
 		if (cl_info->info.hsi_id == hsi->id) {
 			p = hsi_find_port_num(hsi, cl_info->info.port);
 			if (!p)
 				continue;
 			hsi_new_client(p, &cl_info->info);
 		}
 }

 #ifdef CONFIG_OF
 static struct hsi_board_info hsi_char_dev_info = {
 	.name = "hsi_char",
 };

 static int hsi_of_property_parse_mode(struct device_node *client, char *name,
 				      unsigned int *result)
 {
 	const char *mode;
 	int err;

 	err = of_property_read_string(client, name, &mode);
 	if (err < 0)
 		return err;

 	if (strcmp(mode, "stream") == 0)
 		*result = HSI_MODE_STREAM;
 	else if (strcmp(mode, "frame") == 0)
 		*result = HSI_MODE_FRAME;
 	else
 		return -EINVAL;

 	return 0;
 }

 static int hsi_of_property_parse_flow(struct device_node *client, char *name,
 				      unsigned int *result)
 {
 	const char *flow;
 	int err;

 	err = of_property_read_string(client, name, &flow);
 	if (err < 0)
 		return err;

 	if (strcmp(flow, "synchronized") == 0)
 		*result = HSI_FLOW_SYNC;
 	else if (strcmp(flow, "pipeline") == 0)
 		*result = HSI_FLOW_PIPE;
 	else
 		return -EINVAL;

 	return 0;
 }

 static int hsi_of_property_parse_arb_mode(struct device_node *client,
 					  char *name, unsigned int *result)
 {
 	const char *arb_mode;
 	int err;

 	err = of_property_read_string(client, name, &arb_mode);
 	if (err < 0)
 		return err;

 	if (strcmp(arb_mode, "round-robin") == 0)
 		*result = HSI_ARB_RR;
 	else if (strcmp(arb_mode, "priority") == 0)
 		*result = HSI_ARB_PRIO;
 	else
 		return -EINVAL;

 	return 0;
 }

 static void hsi_add_client_from_dt(struct hsi_port *port,
 						struct device_node *client)
 {
 	struct hsi_client *cl;
 	struct hsi_channel channel;
 	struct property *prop;
 	char name[32];
 	int length, cells, err, i, max_chan, mode;

 	cl = kzalloc(sizeof(*cl), GFP_KERNEL);
 	if (!cl)
 		return;

 	err = of_alias_from_compatible(client, name, sizeof(name));
 	if (err)
 		goto err;

 	err = hsi_of_property_parse_mode(client, "hsi-mode", &mode);
 	if (err) {
 		err = hsi_of_property_parse_mode(client, "hsi-rx-mode",
 						 &cl->rx_cfg.mode);
 		if (err)
 			goto err;

 		err = hsi_of_property_parse_mode(client, "hsi-tx-mode",
 						 &cl->tx_cfg.mode);
 		if (err)
 			goto err;
 	} else {
 		cl->rx_cfg.mode = mode;
 		cl->tx_cfg.mode = mode;
 	}

 	err = of_property_read_u32(client, "hsi-speed-kbps",
 				   &cl->tx_cfg.speed);
 	if (err)
 		goto err;
 	cl->rx_cfg.speed = cl->tx_cfg.speed;

 	err = hsi_of_property_parse_flow(client, "hsi-flow",
 					 &cl->rx_cfg.flow);
 	if (err)
 		goto err;

 	err = hsi_of_property_parse_arb_mode(client, "hsi-arb-mode",
 					     &cl->rx_cfg.arb_mode);
 	if (err)
 		goto err;

 	prop = of_find_property(client, "hsi-channel-ids", &length);
 	if (!prop) {
 		err = -EINVAL;
 		goto err;
 	}

 	cells = length / sizeof(u32);

 	cl->rx_cfg.num_channels = cells;
 	cl->tx_cfg.num_channels = cells;
 	cl->rx_cfg.channels = kcalloc(cells, sizeof(channel), GFP_KERNEL);
 	if (!cl->rx_cfg.channels) {
 		err = -ENOMEM;
 		goto err;
 	}

 	cl->tx_cfg.channels = kcalloc(cells, sizeof(channel), GFP_KERNEL);
 	if (!cl->tx_cfg.channels) {
 		err = -ENOMEM;
 		goto err2;
 	}

 	max_chan = 0;
 	for (i = 0; i < cells; i++) {
 		err = of_property_read_u32_index(client, "hsi-channel-ids", i,
 						 &channel.id);
 		if (err)
 			goto err3;

 		err = of_property_read_string_index(client, "hsi-channel-names",
 						    i, &channel.name);
 		if (err)
 			channel.name = NULL;

 		if (channel.id > max_chan)
 			max_chan = channel.id;

 		cl->rx_cfg.channels[i] = channel;
 		cl->tx_cfg.channels[i] = channel;
 	}

 	cl->rx_cfg.num_hw_channels = max_chan + 1;
 	cl->tx_cfg.num_hw_channels = max_chan + 1;

 	cl->device.bus = &hsi_bus_type;
 	cl->device.parent = &port->device;
 	cl->device.release = hsi_client_release;
 	cl->device.of_node = client;

 	dev_set_name(&cl->device, "%s", name);
 	if (device_register(&cl->device) < 0) {
 		pr_err("hsi: failed to register client: %s\n", name);
 		put_device(&cl->device);
 	}

 	return;

 err3:
 	kfree(cl->tx_cfg.channels);
 err2:
 	kfree(cl->rx_cfg.channels);
 err:
 	kfree(cl);
 	pr_err("hsi client: missing or incorrect of property: err=%d\n", err);
 }

 void hsi_add_clients_from_dt(struct hsi_port *port, struct device_node *clients)
 {
 	struct device_node *child;

 	/* register hsi-char device */
 	hsi_new_client(port, &hsi_char_dev_info);

 	for_each_available_child_of_node(clients, child)
 		hsi_add_client_from_dt(port, child);
 }
 EXPORT_SYMBOL_GPL(hsi_add_clients_from_dt);
 #endif

 int hsi_remove_client(struct device *dev, void *data __maybe_unused)
 {
 	device_unregister(dev);

 	return 0;
 }
 EXPORT_SYMBOL_GPL(hsi_remove_client);

 static int hsi_remove_port(struct device *dev, void *data __maybe_unused)
 {
 	device_for_each_child(dev, NULL, hsi_remove_client);
 	device_unregister(dev);

 	return 0;
 }

 static void hsi_controller_release(struct device *dev)
 {
 	struct hsi_controller *hsi = to_hsi_controller(dev);

 	kfree(hsi->port);
 	kfree(hsi);
 }

 static void hsi_port_release(struct device *dev)
 {
 	kfree(to_hsi_port(dev));
 }

 /**
  * hsi_port_unregister_clients - Unregister an HSI port
  * @port: The HSI port to unregister
  */
 void hsi_port_unregister_clients(struct hsi_port *port)
 {
 	device_for_each_child(&port->device, NULL, hsi_remove_client);
 }
 EXPORT_SYMBOL_GPL(hsi_port_unregister_clients);

 /**
  * hsi_unregister_controller - Unregister an HSI controller
  * @hsi: The HSI controller to register
  */
 void hsi_unregister_controller(struct hsi_controller *hsi)
 {
 	device_for_each_child(&hsi->device, NULL, hsi_remove_port);
 	device_unregister(&hsi->device);
 }
 EXPORT_SYMBOL_GPL(hsi_unregister_controller);

 /**
  * hsi_register_controller - Register an HSI controller and its ports
  * @hsi: The HSI controller to register
  *
  * Returns -errno on failure, 0 on success.
  */
 int hsi_register_controller(struct hsi_controller *hsi)
 {
 	unsigned int i;
 	int err;

 	err = device_add(&hsi->device);
 	if (err < 0)
 		return err;
 	for (i = 0; i < hsi->num_ports; i++) {
 		hsi->port[i]->device.parent = &hsi->device;
 		err = device_add(&hsi->port[i]->device);
 		if (err < 0)
 			goto out;
 	}
 	/* Populate HSI bus with HSI clients */
 	hsi_scan_board_info(hsi);

 	return 0;
 out:
 	while (i-- > 0)
 		device_del(&hsi->port[i]->device);
 	device_del(&hsi->device);

 	return err;
 }
 EXPORT_SYMBOL_GPL(hsi_register_controller);

 /**
  * hsi_register_client_driver - Register an HSI client to the HSI bus
  * @drv: HSI client driver to register
  *
  * Returns -errno on failure, 0 on success.
  */
 int hsi_register_client_driver(struct hsi_client_driver *drv)
 {
 	drv->driver.bus = &hsi_bus_type;

 	return driver_register(&drv->driver);
 }
 EXPORT_SYMBOL_GPL(hsi_register_client_driver);

 static inline int hsi_dummy_msg(struct hsi_msg *msg __maybe_unused)
 {
 	return 0;
 }

 static inline int hsi_dummy_cl(struct hsi_client *cl __maybe_unused)
 {
 	return 0;
 }

 /**
  * hsi_put_controller - Free an HSI controller
  *
  * @hsi: Pointer to the HSI controller to freed
  *
  * HSI controller drivers should only use this function if they need
  * to free their allocated hsi_controller structures before a successful
  * call to hsi_register_controller. Other use is not allowed.
  */
 void hsi_put_controller(struct hsi_controller *hsi)
 {
 	unsigned int i;

 	if (!hsi)
 		return;

 	for (i = 0; i < hsi->num_ports; i++)
 		if (hsi->port && hsi->port[i])
 			put_device(&hsi->port[i]->device);
 	put_device(&hsi->device);
 }
 EXPORT_SYMBOL_GPL(hsi_put_controller);

 /**
  * hsi_alloc_controller - Allocate an HSI controller and its ports
  * @n_ports: Number of ports on the HSI controller
  * @flags: Kernel allocation flags
  *
  * Return NULL on failure or a pointer to an hsi_controller on success.
  */
 struct hsi_controller *hsi_alloc_controller(unsigned int n_ports, gfp_t flags)
 {
 	struct hsi_controller	*hsi;
 	struct hsi_port		**port;
 	unsigned int		i;

 	if (!n_ports)
 		return NULL;

 	hsi = kzalloc(sizeof(*hsi), flags);
 	if (!hsi)
 		return NULL;
 	port = kcalloc(n_ports, sizeof(*port), flags);
 	if (!port) {
 		kfree(hsi);
 		return NULL;
 	}
 	hsi->num_ports = n_ports;
 	hsi->port = port;
 	hsi->device.release = hsi_controller_release;
 	device_initialize(&hsi->device);

 	for (i = 0; i < n_ports; i++) {
 		port[i] = kzalloc(sizeof(**port), flags);
 		if (port[i] == NULL)
 			goto out;
 		port[i]->num = i;
 		port[i]->async = hsi_dummy_msg;
 		port[i]->setup = hsi_dummy_cl;
 		port[i]->flush = hsi_dummy_cl;
 		port[i]->start_tx = hsi_dummy_cl;
 		port[i]->stop_tx = hsi_dummy_cl;
 		port[i]->release = hsi_dummy_cl;
 		mutex_init(&port[i]->lock);
 		BLOCKING_INIT_NOTIFIER_HEAD(&port[i]->n_head);
 		dev_set_name(&port[i]->device, "port%d", i);
 		hsi->port[i]->device.release = hsi_port_release;
 		device_initialize(&hsi->port[i]->device);
 	}

 	return hsi;
 out:
 	hsi_put_controller(hsi);

 	return NULL;
 }
 EXPORT_SYMBOL_GPL(hsi_alloc_controller);

 /**
  * hsi_free_msg - Free an HSI message
  * @msg: Pointer to the HSI message
  *
  * Client is responsible to free the buffers pointed by the scatterlists.
  */
 void hsi_free_msg(struct hsi_msg *msg)
 {
 	if (!msg)
 		return;
 	sg_free_table(&msg->sgt);
 	kfree(msg);
 }
 EXPORT_SYMBOL_GPL(hsi_free_msg);

 /**
  * hsi_alloc_msg - Allocate an HSI message
  * @nents: Number of memory entries
  * @flags: Kernel allocation flags
  *
  * nents can be 0. This mainly makes sense for read transfer.
  * In that case, HSI drivers will call the complete callback when
  * there is data to be read without consuming it.
  *
  * Return NULL on failure or a pointer to an hsi_msg on success.
  */
 struct hsi_msg *hsi_alloc_msg(unsigned int nents, gfp_t flags)
 {
 	struct hsi_msg *msg;
 	int err;

 	msg = kzalloc(sizeof(*msg), flags);
 	if (!msg)
 		return NULL;

 	if (!nents)
 		return msg;

 	err = sg_alloc_table(&msg->sgt, nents, flags);
 	if (unlikely(err)) {
 		kfree(msg);
 		msg = NULL;
 	}

 	return msg;
 }
 EXPORT_SYMBOL_GPL(hsi_alloc_msg);

 /**
  * hsi_async - Submit an HSI transfer to the controller
  * @cl: HSI client sending the transfer
  * @msg: The HSI transfer passed to controller
  *
  * The HSI message must have the channel, ttype, complete and destructor
  * fields set beforehand. If nents > 0 then the client has to initialize
  * also the scatterlists to point to the buffers to write to or read from.
  *
  * HSI controllers relay on pre-allocated buffers from their clients and they
  * do not allocate buffers on their own.
  *
  * Once the HSI message transfer finishes, the HSI controller calls the
  * complete callback with the status and actual_len fields of the HSI message
  * updated. The complete callback can be called before returning from
  * hsi_async.
  *
  * Returns -errno on failure or 0 on success
  */
 int hsi_async(struct hsi_client *cl, struct hsi_msg *msg)
 {
 	struct hsi_port *port = hsi_get_port(cl);

 	if (!hsi_port_claimed(cl))
 		return -EACCES;

 	WARN_ON_ONCE(!msg->destructor || !msg->complete);
 	msg->cl = cl;

 	return port->async(msg);
 }
 EXPORT_SYMBOL_GPL(hsi_async);

 /**
  * hsi_claim_port - Claim the HSI client's port
  * @cl: HSI client that wants to claim its port
  * @share: Flag to indicate if the client wants to share the port or not.
  *
  * Returns -errno on failure, 0 on success.
  */
 int hsi_claim_port(struct hsi_client *cl, unsigned int share)
 {
 	struct hsi_port *port = hsi_get_port(cl);
 	int err = 0;

 	mutex_lock(&port->lock);
 	if ((port->claimed) && (!port->shared || !share)) {
 		err = -EBUSY;
 		goto out;
 	}
 	if (!try_module_get(to_hsi_controller(port->device.parent)->owner)) {
 		err = -ENODEV;
 		goto out;
 	}
 	port->claimed++;
 	port->shared = !!share;
 	cl->pclaimed = 1;
 out:
 	mutex_unlock(&port->lock);

 	return err;
 }
 EXPORT_SYMBOL_GPL(hsi_claim_port);

 /**
  * hsi_release_port - Release the HSI client's port
  * @cl: HSI client which previously claimed its port
  */
 void hsi_release_port(struct hsi_client *cl)
 {
 	struct hsi_port *port = hsi_get_port(cl);

 	mutex_lock(&port->lock);
 	/* Allow HW driver to do some cleanup */
 	port->release(cl);
 	if (cl->pclaimed)
 		port->claimed--;
 	BUG_ON(port->claimed < 0);
 	cl->pclaimed = 0;
 	if (!port->claimed)
 		port->shared = 0;
 	module_put(to_hsi_controller(port->device.parent)->owner);
 	mutex_unlock(&port->lock);
 }
 EXPORT_SYMBOL_GPL(hsi_release_port);

 static int hsi_event_notifier_call(struct notifier_block *nb,
 				unsigned long event, void *data __maybe_unused)
 {
 	struct hsi_client *cl = container_of(nb, struct hsi_client, nb);

 	(*cl->ehandler)(cl, event);

 	return 0;
 }

 /**
  * hsi_register_port_event - Register a client to receive port events
  * @cl: HSI client that wants to receive port events
  * @handler: Event handler callback
  *
  * Clients should register a callback to be able to receive
  * events from the ports. Registration should happen after
  * claiming the port.
  * The handler can be called in interrupt context.
  *
  * Returns -errno on error, or 0 on success.
  */
 int hsi_register_port_event(struct hsi_client *cl,
 			void (*handler)(struct hsi_client *, unsigned long))
 {
 	struct hsi_port *port = hsi_get_port(cl);

 	if (!handler || cl->ehandler)
 		return -EINVAL;
 	if (!hsi_port_claimed(cl))
 		return -EACCES;
 	cl->ehandler = handler;
 	cl->nb.notifier_call = hsi_event_notifier_call;

 	return blocking_notifier_chain_register(&port->n_head, &cl->nb);
 }
 EXPORT_SYMBOL_GPL(hsi_register_port_event);

 /**
  * hsi_unregister_port_event - Stop receiving port events for a client
  * @cl: HSI client that wants to stop receiving port events
  *
  * Clients should call this function before releasing their associated
  * port.
  *
  * Returns -errno on error, or 0 on success.
  */
 int hsi_unregister_port_event(struct hsi_client *cl)
 {
 	struct hsi_port *port = hsi_get_port(cl);
 	int err;

 	WARN_ON(!hsi_port_claimed(cl));

 	err = blocking_notifier_chain_unregister(&port->n_head, &cl->nb);
 	if (!err)
 		cl->ehandler = NULL;

 	return err;
 }
 EXPORT_SYMBOL_GPL(hsi_unregister_port_event);

 /**
  * hsi_event - Notifies clients about port events
  * @port: Port where the event occurred
  * @event: The event type
  *
  * Clients should not be concerned about wake line behavior. However, due
  * to a race condition in HSI HW protocol, clients need to be notified
  * about wake line changes, so they can implement a workaround for it.
  *
  * Events:
  * HSI_EVENT_START_RX - Incoming wake line high
  * HSI_EVENT_STOP_RX - Incoming wake line down
  *
  * Returns -errno on error, or 0 on success.
  */
 int hsi_event(struct hsi_port *port, unsigned long event)
 {
 	return blocking_notifier_call_chain(&port->n_head, event, NULL);
 }
 EXPORT_SYMBOL_GPL(hsi_event);

 /**
  * hsi_get_channel_id_by_name - acquire channel id by channel name
  * @cl: HSI client, which uses the channel
  * @name: name the channel is known under
  *
  * Clients can call this function to get the hsi channel ids similar to
  * requesting IRQs or GPIOs by name. This function assumes the same
  * channel configuration is used for RX and TX.
  *
  * Returns -errno on error or channel id on success.
  */
 int hsi_get_channel_id_by_name(struct hsi_client *cl, char *name)
 {
 	int i;

 	if (!cl->rx_cfg.channels)
 		return -ENOENT;

 	for (i = 0; i < cl->rx_cfg.num_channels; i++)
 		if (!strcmp(cl->rx_cfg.channels[i].name, name))
 			return cl->rx_cfg.channels[i].id;

 	return -ENXIO;
 }
 EXPORT_SYMBOL_GPL(hsi_get_channel_id_by_name);

 static int __init hsi_init(void)
 {
 	return bus_register(&hsi_bus_type);
 }
 postcore_initcall(hsi_init);

 static void __exit hsi_exit(void)
 {
 	bus_unregister(&hsi_bus_type);
 }
 module_exit(hsi_exit);

 MODULE_AUTHOR("Carlos Chinea <carlos.chinea@nokia.com>");
 MODULE_DESCRIPTION("High-speed Synchronous Serial Interface (HSI) framework");
 MODULE_LICENSE("GPL v2");
	// SPDX-License-Identifier: GPL-2.0-only
	/*
	* HSI core.
	*
	* Copyright (C) 2010 Nokia Corporation. All rights reserved.
	*
	* Contact: Carlos Chinea <carlos.chinea@nokia.com>
	*/
	#include <linux/hsi/hsi.h>
	#include <linux/compiler.h>
	#include <linux/list.h>
	#include <linux/kobject.h>
	#include <linux/slab.h>
	#include <linux/string.h>
	#include <linux/notifier.h>
	#include <linux/of.h>
	#include <linux/of_device.h>
	#include "hsi_core.h"

	static ssize_t modalias_show(struct device *dev,
	struct device_attribute a __maybe_unused, char buf)
	{
	return sprintf(buf, "hsi:%s\n", dev_name(dev));
	}
	static DEVICE_ATTR_RO(modalias);

	static struct attribute *hsi_bus_dev_attrs[] = {
	&dev_attr_modalias.attr,
	NULL,
	};
	ATTRIBUTE_GROUPS(hsi_bus_dev);

	static int hsi_bus_uevent(const struct device dev, struct kobj_uevent_env env)
	{
	add_uevent_var(env, "MODALIAS=hsi:%s", dev_name(dev));

	return 0;
	}

	static int hsi_bus_match(struct device dev, struct device_driver driver)
	{
	if (of_driver_match_device(dev, driver))
	return true;

	if (strcmp(dev_name(dev), driver->name) == 0)
	return true;

	return false;
	}

	static struct bus_type hsi_bus_type = {
	.name = "hsi",
	.dev_groups = hsi_bus_dev_groups,
	.match = hsi_bus_match,
	.uevent = hsi_bus_uevent,
	};

	static void hsi_client_release(struct device *dev)
	{
	struct hsi_client *cl = to_hsi_client(dev);

	kfree(cl->tx_cfg.channels);
	kfree(cl->rx_cfg.channels);
	kfree(cl);
	}

	struct hsi_client hsi_new_client(struct hsi_port port,
	struct hsi_board_info *info)
	{
	struct hsi_client *cl;
	size_t size;

	cl = kzalloc(sizeof(*cl), GFP_KERNEL);
	if (!cl)
	goto err;

	cl->tx_cfg = info->tx_cfg;
	if (cl->tx_cfg.channels) {
	size = cl->tx_cfg.num_channels * sizeof(*cl->tx_cfg.channels);
	cl->tx_cfg.channels = kmemdup(info->tx_cfg.channels, size,
	GFP_KERNEL);
	if (!cl->tx_cfg.channels)
	goto err_tx;
	}

	cl->rx_cfg = info->rx_cfg;
	if (cl->rx_cfg.channels) {
	size = cl->rx_cfg.num_channels * sizeof(*cl->rx_cfg.channels);
	cl->rx_cfg.channels = kmemdup(info->rx_cfg.channels, size,
	GFP_KERNEL);
	if (!cl->rx_cfg.channels)
	goto err_rx;
	}

	cl->device.bus = &hsi_bus_type;
	cl->device.parent = &port->device;
	cl->device.release = hsi_client_release;
	dev_set_name(&cl->device, "%s", info->name);
	cl->device.platform_data = info->platform_data;
	if (info->archdata)
	cl->device.archdata = *info->archdata;
	if (device_register(&cl->device) < 0) {
	pr_err("hsi: failed to register client: %s\n", info->name);
	put_device(&cl->device);
	goto err;
	}

	return cl;
	err_rx:
	kfree(cl->tx_cfg.channels);
	err_tx:
	kfree(cl);
	err:
	return NULL;
	}
	EXPORT_SYMBOL_GPL(hsi_new_client);

	static void hsi_scan_board_info(struct hsi_controller *hsi)
	{
	struct hsi_cl_info *cl_info;
	struct hsi_port *p;

	list_for_each_entry(cl_info, &hsi_board_list, list)
	if (cl_info->info.hsi_id == hsi->id) {
	p = hsi_find_port_num(hsi, cl_info->info.port);
	if (!p)
	continue;
	hsi_new_client(p, &cl_info->info);
	}
	}

	#ifdef CONFIG_OF
	static struct hsi_board_info hsi_char_dev_info = {
	.name = "hsi_char",
	};

	static int hsi_of_property_parse_mode(struct device_node client, char name,
	unsigned int *result)
	{
	const char *mode;
	int err;

	err = of_property_read_string(client, name, &mode);
	if (err < 0)
	return err;

	if (strcmp(mode, "stream") == 0)
	*result = HSI_MODE_STREAM;
	else if (strcmp(mode, "frame") == 0)
	*result = HSI_MODE_FRAME;
	else
	return -EINVAL;

	return 0;
	}

	static int hsi_of_property_parse_flow(struct device_node client, char name,
	unsigned int *result)
	{
	const char *flow;
	int err;

	err = of_property_read_string(client, name, &flow);
	if (err < 0)
	return err;

	if (strcmp(flow, "synchronized") == 0)
	*result = HSI_FLOW_SYNC;
	else if (strcmp(flow, "pipeline") == 0)
	*result = HSI_FLOW_PIPE;
	else
	return -EINVAL;

	return 0;
	}

	static int hsi_of_property_parse_arb_mode(struct device_node *client,
	char name, unsigned int result)
	{
	const char *arb_mode;
	int err;

	err = of_property_read_string(client, name, &arb_mode);
	if (err < 0)
	return err;

	if (strcmp(arb_mode, "round-robin") == 0)
	*result = HSI_ARB_RR;
	else if (strcmp(arb_mode, "priority") == 0)
	*result = HSI_ARB_PRIO;
	else
	return -EINVAL;

	return 0;
	}

	static void hsi_add_client_from_dt(struct hsi_port *port,
	struct device_node *client)
	{
	struct hsi_client *cl;
	struct hsi_channel channel;
	struct property *prop;
	char name[32];
	int length, cells, err, i, max_chan, mode;

	cl = kzalloc(sizeof(*cl), GFP_KERNEL);
	if (!cl)
	return;

	err = of_alias_from_compatible(client, name, sizeof(name));
	if (err)
	goto err;

	err = hsi_of_property_parse_mode(client, "hsi-mode", &mode);
	if (err) {
	err = hsi_of_property_parse_mode(client, "hsi-rx-mode",
	&cl->rx_cfg.mode);
	if (err)
	goto err;

	err = hsi_of_property_parse_mode(client, "hsi-tx-mode",
	&cl->tx_cfg.mode);
	if (err)
	goto err;
	} else {
	cl->rx_cfg.mode = mode;
	cl->tx_cfg.mode = mode;
	}

	err = of_property_read_u32(client, "hsi-speed-kbps",
	&cl->tx_cfg.speed);
	if (err)
	goto err;
	cl->rx_cfg.speed = cl->tx_cfg.speed;

	err = hsi_of_property_parse_flow(client, "hsi-flow",
	&cl->rx_cfg.flow);
	if (err)
	goto err;

	err = hsi_of_property_parse_arb_mode(client, "hsi-arb-mode",
	&cl->rx_cfg.arb_mode);
	if (err)
	goto err;

	prop = of_find_property(client, "hsi-channel-ids", &length);
	if (!prop) {
	err = -EINVAL;
	goto err;
	}

	cells = length / sizeof(u32);

	cl->rx_cfg.num_channels = cells;
	cl->tx_cfg.num_channels = cells;
	cl->rx_cfg.channels = kcalloc(cells, sizeof(channel), GFP_KERNEL);
	if (!cl->rx_cfg.channels) {
	err = -ENOMEM;
	goto err;
	}

	cl->tx_cfg.channels = kcalloc(cells, sizeof(channel), GFP_KERNEL);
	if (!cl->tx_cfg.channels) {
	err = -ENOMEM;
	goto err2;
	}

	max_chan = 0;
	for (i = 0; i < cells; i++) {
	err = of_property_read_u32_index(client, "hsi-channel-ids", i,
	&channel.id);
	if (err)
	goto err3;

	err = of_property_read_string_index(client, "hsi-channel-names",
	i, &channel.name);
	if (err)
	channel.name = NULL;

	if (channel.id > max_chan)
	max_chan = channel.id;

	cl->rx_cfg.channels[i] = channel;
	cl->tx_cfg.channels[i] = channel;
	}

	cl->rx_cfg.num_hw_channels = max_chan + 1;
	cl->tx_cfg.num_hw_channels = max_chan + 1;

	cl->device.bus = &hsi_bus_type;
	cl->device.parent = &port->device;
	cl->device.release = hsi_client_release;
	cl->device.of_node = client;

	dev_set_name(&cl->device, "%s", name);
	if (device_register(&cl->device) < 0) {
	pr_err("hsi: failed to register client: %s\n", name);
	put_device(&cl->device);
	}

	return;

	err3:
	kfree(cl->tx_cfg.channels);
	err2:
	kfree(cl->rx_cfg.channels);
	err:
	kfree(cl);
	pr_err("hsi client: missing or incorrect of property: err=%d\n", err);
	}

	void hsi_add_clients_from_dt(struct hsi_port port, struct device_node clients)
	{
	struct device_node *child;

	/* register hsi-char device */
	hsi_new_client(port, &hsi_char_dev_info);

	for_each_available_child_of_node(clients, child)
	hsi_add_client_from_dt(port, child);
	}
	EXPORT_SYMBOL_GPL(hsi_add_clients_from_dt);
	#endif

	int hsi_remove_client(struct device dev, void data __maybe_unused)
	{
	device_unregister(dev);

	return 0;
	}
	EXPORT_SYMBOL_GPL(hsi_remove_client);

	static int hsi_remove_port(struct device dev, void data __maybe_unused)
	{
	device_for_each_child(dev, NULL, hsi_remove_client);
	device_unregister(dev);

	return 0;
	}

	static void hsi_controller_release(struct device *dev)
	{
	struct hsi_controller *hsi = to_hsi_controller(dev);

	kfree(hsi->port);
	kfree(hsi);
	}

	static void hsi_port_release(struct device *dev)
	{
	kfree(to_hsi_port(dev));
	}

	/**
	* hsi_port_unregister_clients - Unregister an HSI port
	* @port: The HSI port to unregister
	*/
	void hsi_port_unregister_clients(struct hsi_port *port)
	{
	device_for_each_child(&port->device, NULL, hsi_remove_client);
	}
	EXPORT_SYMBOL_GPL(hsi_port_unregister_clients);

	/**
	* hsi_unregister_controller - Unregister an HSI controller
	* @hsi: The HSI controller to register
	*/
	void hsi_unregister_controller(struct hsi_controller *hsi)
	{
	device_for_each_child(&hsi->device, NULL, hsi_remove_port);
	device_unregister(&hsi->device);
	}
	EXPORT_SYMBOL_GPL(hsi_unregister_controller);

	/**
	* hsi_register_controller - Register an HSI controller and its ports
	* @hsi: The HSI controller to register
	*
	* Returns -errno on failure, 0 on success.
	*/
	int hsi_register_controller(struct hsi_controller *hsi)
	{
	unsigned int i;
	int err;

	err = device_add(&hsi->device);
	if (err < 0)
	return err;
	for (i = 0; i < hsi->num_ports; i++) {
	hsi->port[i]->device.parent = &hsi->device;
	err = device_add(&hsi->port[i]->device);
	if (err < 0)
	goto out;
	}
	/* Populate HSI bus with HSI clients */
	hsi_scan_board_info(hsi);

	return 0;
	out:
	while (i-- > 0)
	device_del(&hsi->port[i]->device);
	device_del(&hsi->device);

	return err;
	}
	EXPORT_SYMBOL_GPL(hsi_register_controller);

	/**
	* hsi_register_client_driver - Register an HSI client to the HSI bus
	* @drv: HSI client driver to register
	*
	* Returns -errno on failure, 0 on success.
	*/
	int hsi_register_client_driver(struct hsi_client_driver *drv)
	{
	drv->driver.bus = &hsi_bus_type;

	return driver_register(&drv->driver);
	}
	EXPORT_SYMBOL_GPL(hsi_register_client_driver);

	static inline int hsi_dummy_msg(struct hsi_msg *msg __maybe_unused)
	{
	return 0;
	}

	static inline int hsi_dummy_cl(struct hsi_client *cl __maybe_unused)
	{
	return 0;
	}

	/**
	* hsi_put_controller - Free an HSI controller
	*
	* @hsi: Pointer to the HSI controller to freed
	*
	* HSI controller drivers should only use this function if they need
	* to free their allocated hsi_controller structures before a successful
	* call to hsi_register_controller. Other use is not allowed.
	*/
	void hsi_put_controller(struct hsi_controller *hsi)
	{
	unsigned int i;

	if (!hsi)
	return;

	for (i = 0; i < hsi->num_ports; i++)
	if (hsi->port && hsi->port[i])
	put_device(&hsi->port[i]->device);
	put_device(&hsi->device);
	}
	EXPORT_SYMBOL_GPL(hsi_put_controller);

	/**
	* hsi_alloc_controller - Allocate an HSI controller and its ports
	* @n_ports: Number of ports on the HSI controller
	* @flags: Kernel allocation flags
	*
	* Return NULL on failure or a pointer to an hsi_controller on success.
	*/
	struct hsi_controller *hsi_alloc_controller(unsigned int n_ports, gfp_t flags)
	{
	struct hsi_controller *hsi;
	struct hsi_port **port;
	unsigned int i;

	if (!n_ports)
	return NULL;

	hsi = kzalloc(sizeof(*hsi), flags);
	if (!hsi)
	return NULL;
	port = kcalloc(n_ports, sizeof(*port), flags);
	if (!port) {
	kfree(hsi);
	return NULL;
	}
	hsi->num_ports = n_ports;
	hsi->port = port;
	hsi->device.release = hsi_controller_release;
	device_initialize(&hsi->device);

	for (i = 0; i < n_ports; i++) {
	port[i] = kzalloc(sizeof(**port), flags);
	if (port[i] == NULL)
	goto out;
	port[i]->num = i;
	port[i]->async = hsi_dummy_msg;
	port[i]->setup = hsi_dummy_cl;
	port[i]->flush = hsi_dummy_cl;
	port[i]->start_tx = hsi_dummy_cl;
	port[i]->stop_tx = hsi_dummy_cl;
	port[i]->release = hsi_dummy_cl;
	mutex_init(&port[i]->lock);
	BLOCKING_INIT_NOTIFIER_HEAD(&port[i]->n_head);
	dev_set_name(&port[i]->device, "port%d", i);
	hsi->port[i]->device.release = hsi_port_release;
	device_initialize(&hsi->port[i]->device);
	}

	return hsi;
	out:
	hsi_put_controller(hsi);

	return NULL;
	}
	EXPORT_SYMBOL_GPL(hsi_alloc_controller);

	/**
	* hsi_free_msg - Free an HSI message
	* @msg: Pointer to the HSI message
	*
	* Client is responsible to free the buffers pointed by the scatterlists.
	*/
	void hsi_free_msg(struct hsi_msg *msg)
	{
	if (!msg)
	return;
	sg_free_table(&msg->sgt);
	kfree(msg);
	}
	EXPORT_SYMBOL_GPL(hsi_free_msg);

	/**
	* hsi_alloc_msg - Allocate an HSI message
	* @nents: Number of memory entries
	* @flags: Kernel allocation flags
	*
	* nents can be 0. This mainly makes sense for read transfer.
	* In that case, HSI drivers will call the complete callback when
	* there is data to be read without consuming it.
	*
	* Return NULL on failure or a pointer to an hsi_msg on success.
	*/
	struct hsi_msg *hsi_alloc_msg(unsigned int nents, gfp_t flags)
	{
	struct hsi_msg *msg;
	int err;

	msg = kzalloc(sizeof(*msg), flags);
	if (!msg)
	return NULL;

	if (!nents)
	return msg;

	err = sg_alloc_table(&msg->sgt, nents, flags);
	if (unlikely(err)) {
	kfree(msg);
	msg = NULL;
	}

	return msg;
	}
	EXPORT_SYMBOL_GPL(hsi_alloc_msg);

	/**
	* hsi_async - Submit an HSI transfer to the controller
	* @cl: HSI client sending the transfer
	* @msg: The HSI transfer passed to controller
	*
	* The HSI message must have the channel, ttype, complete and destructor
	* fields set beforehand. If nents > 0 then the client has to initialize
	* also the scatterlists to point to the buffers to write to or read from.
	*
	* HSI controllers relay on pre-allocated buffers from their clients and they
	* do not allocate buffers on their own.
	*
	* Once the HSI message transfer finishes, the HSI controller calls the
	* complete callback with the status and actual_len fields of the HSI message
	* updated. The complete callback can be called before returning from
	* hsi_async.
	*
	* Returns -errno on failure or 0 on success
	*/
	int hsi_async(struct hsi_client cl, struct hsi_msg msg)
	{
	struct hsi_port *port = hsi_get_port(cl);

	if (!hsi_port_claimed(cl))
	return -EACCES;

	WARN_ON_ONCE(!msg->destructor \|\| !msg->complete);
	msg->cl = cl;

	return port->async(msg);
	}
	EXPORT_SYMBOL_GPL(hsi_async);

	/**
	* hsi_claim_port - Claim the HSI client's port
	* @cl: HSI client that wants to claim its port
	* @share: Flag to indicate if the client wants to share the port or not.
	*
	* Returns -errno on failure, 0 on success.
	*/
	int hsi_claim_port(struct hsi_client *cl, unsigned int share)
	{
	struct hsi_port *port = hsi_get_port(cl);
	int err = 0;

	mutex_lock(&port->lock);
	if ((port->claimed) && (!port->shared \|\| !share)) {
	err = -EBUSY;
	goto out;
	}
	if (!try_module_get(to_hsi_controller(port->device.parent)->owner)) {
	err = -ENODEV;
	goto out;
	}
	port->claimed++;
	port->shared = !!share;
	cl->pclaimed = 1;
	out:
	mutex_unlock(&port->lock);

	return err;
	}
	EXPORT_SYMBOL_GPL(hsi_claim_port);

	/**
	* hsi_release_port - Release the HSI client's port
	* @cl: HSI client which previously claimed its port
	*/
	void hsi_release_port(struct hsi_client *cl)
	{
	struct hsi_port *port = hsi_get_port(cl);

	mutex_lock(&port->lock);
	/* Allow HW driver to do some cleanup */
	port->release(cl);
	if (cl->pclaimed)
	port->claimed--;
	BUG_ON(port->claimed < 0);
	cl->pclaimed = 0;
	if (!port->claimed)
	port->shared = 0;
	module_put(to_hsi_controller(port->device.parent)->owner);
	mutex_unlock(&port->lock);
	}
	EXPORT_SYMBOL_GPL(hsi_release_port);

	static int hsi_event_notifier_call(struct notifier_block *nb,
	unsigned long event, void *data __maybe_unused)
	{
	struct hsi_client *cl = container_of(nb, struct hsi_client, nb);

	(*cl->ehandler)(cl, event);

	return 0;
	}

	/**
	* hsi_register_port_event - Register a client to receive port events
	* @cl: HSI client that wants to receive port events
	* @handler: Event handler callback
	*
	* Clients should register a callback to be able to receive
	* events from the ports. Registration should happen after
	* claiming the port.
	* The handler can be called in interrupt context.
	*
	* Returns -errno on error, or 0 on success.
	*/
	int hsi_register_port_event(struct hsi_client *cl,
	void (handler)(struct hsi_client , unsigned long))
	{
	struct hsi_port *port = hsi_get_port(cl);

	if (!handler \|\| cl->ehandler)
	return -EINVAL;
	if (!hsi_port_claimed(cl))
	return -EACCES;
	cl->ehandler = handler;
	cl->nb.notifier_call = hsi_event_notifier_call;

	return blocking_notifier_chain_register(&port->n_head, &cl->nb);
	}
	EXPORT_SYMBOL_GPL(hsi_register_port_event);

	/**
	* hsi_unregister_port_event - Stop receiving port events for a client
	* @cl: HSI client that wants to stop receiving port events
	*
	* Clients should call this function before releasing their associated
	* port.
	*
	* Returns -errno on error, or 0 on success.
	*/
	int hsi_unregister_port_event(struct hsi_client *cl)
	{
	struct hsi_port *port = hsi_get_port(cl);
	int err;

	WARN_ON(!hsi_port_claimed(cl));

	err = blocking_notifier_chain_unregister(&port->n_head, &cl->nb);
	if (!err)
	cl->ehandler = NULL;

	return err;
	}
	EXPORT_SYMBOL_GPL(hsi_unregister_port_event);

	/**
	* hsi_event - Notifies clients about port events
	* @port: Port where the event occurred
	* @event: The event type
	*
	* Clients should not be concerned about wake line behavior. However, due
	* to a race condition in HSI HW protocol, clients need to be notified
	* about wake line changes, so they can implement a workaround for it.
	*
	* Events:
	* HSI_EVENT_START_RX - Incoming wake line high
	* HSI_EVENT_STOP_RX - Incoming wake line down
	*
	* Returns -errno on error, or 0 on success.
	*/
	int hsi_event(struct hsi_port *port, unsigned long event)
	{
	return blocking_notifier_call_chain(&port->n_head, event, NULL);
	}
	EXPORT_SYMBOL_GPL(hsi_event);

	/**
	* hsi_get_channel_id_by_name - acquire channel id by channel name
	* @cl: HSI client, which uses the channel
	* @name: name the channel is known under
	*
	* Clients can call this function to get the hsi channel ids similar to
	* requesting IRQs or GPIOs by name. This function assumes the same
	* channel configuration is used for RX and TX.
	*
	* Returns -errno on error or channel id on success.
	*/
	int hsi_get_channel_id_by_name(struct hsi_client cl, char name)
	{
	int i;

	if (!cl->rx_cfg.channels)
	return -ENOENT;

	for (i = 0; i < cl->rx_cfg.num_channels; i++)
	if (!strcmp(cl->rx_cfg.channels[i].name, name))
	return cl->rx_cfg.channels[i].id;

	return -ENXIO;
	}
	EXPORT_SYMBOL_GPL(hsi_get_channel_id_by_name);

	static int __init hsi_init(void)
	{
	return bus_register(&hsi_bus_type);
	}
	postcore_initcall(hsi_init);

	static void __exit hsi_exit(void)
	{
	bus_unregister(&hsi_bus_type);
	}
	module_exit(hsi_exit);

	MODULE_AUTHOR("Carlos Chinea <carlos.chinea@nokia.com>");
	MODULE_DESCRIPTION("High-speed Synchronous Serial Interface (HSI) framework");
	MODULE_LICENSE("GPL v2");