/*
   * HSI core.
   *
   * Copyright (C) 2010 Nokia Corporation. All rights reserved.
   *
   * Contact: Carlos Chinea <carlos.chinea@nokia.com>
   *
   * This program is free software; you can redistribute it and/or
   * modify it under the terms of the GNU General Public License
   * version 2 as published by the Free Software Foundation.
   *
   * This program is distributed in the hope that it will be useful, but
   * WITHOUT ANY WARRANTY; without even the implied warranty of
   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   * General Public License for more details.
   *
   * You should have received a copy of the GNU General Public License
   * along with this program; if not, write to the Free Software
   * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
   * 02110-1301 USA
   */
  #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 "hsi_core.h"
  
  static ssize_t modalias_show(struct device *dev,
  			struct device_attribute *a __maybe_unused, char *buf)
  {
  	return sprintf(buf, "hsi:%s
  ", 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(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)
  {
  	return strcmp(dev_name(dev), driver->name) == 0;
  }
  
  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)
  {
  	kfree(to_hsi_client(dev));
  }
  
  static void hsi_new_client(struct hsi_port *port, struct hsi_board_info *info)
  {
  	struct hsi_client *cl;
  
  	cl = kzalloc(sizeof(*cl), GFP_KERNEL);
  	if (!cl)
  		return;
  	cl->tx_cfg = info->tx_cfg;
  	cl->rx_cfg = info->rx_cfg;
  	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
  ", info->name);
  		put_device(&cl->device);
  	}
  }
  
  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);
  		}
  }
  
  static int hsi_remove_client(struct device *dev, void *data __maybe_unused)
  {
  	device_unregister(dev);
  
  	return 0;
  }
  
  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_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 = kzalloc(sizeof(*port)*n_ports, 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);
  		ATOMIC_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 atomic_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 = atomic_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 atomic_notifier_call_chain(&port->n_head, event, NULL);
  }
  EXPORT_SYMBOL_GPL(hsi_event);
  
  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");