/*
   *  Texas Instruments' Bluetooth HCILL UART protocol
   *
   *  HCILL (HCI Low Level) is a Texas Instruments' power management
   *  protocol extension to H4.
   *
   *  Copyright (C) 2007 Texas Instruments, Inc.
   *
   *  Written by Ohad Ben-Cohen <ohad@bencohen.org>
   *
   *  Acknowledgements:
   *  This file is based on hci_h4.c, which was written
   *  by Maxim Krasnyansky and Marcel Holtmann.
   *
   *  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., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
   *
   */
  
  #include <linux/module.h>
  #include <linux/kernel.h>
  
  #include <linux/init.h>
  #include <linux/sched.h>
  #include <linux/types.h>
  #include <linux/fcntl.h>
  #include <linux/interrupt.h>
  #include <linux/ptrace.h>
  #include <linux/poll.h>
  
  #include <linux/slab.h>
  #include <linux/tty.h>
  #include <linux/errno.h>
  #include <linux/string.h>
  #include <linux/signal.h>
  #include <linux/ioctl.h>
  #include <linux/skbuff.h>
  
  #include <net/bluetooth/bluetooth.h>
  #include <net/bluetooth/hci_core.h>
  
  #include "hci_uart.h"
  
  /* HCILL commands */
  #define HCILL_GO_TO_SLEEP_IND	0x30
  #define HCILL_GO_TO_SLEEP_ACK	0x31
  #define HCILL_WAKE_UP_IND	0x32
  #define HCILL_WAKE_UP_ACK	0x33
  
  /* HCILL receiver States */
  #define HCILL_W4_PACKET_TYPE	0
  #define HCILL_W4_EVENT_HDR	1
  #define HCILL_W4_ACL_HDR	2
  #define HCILL_W4_SCO_HDR	3
  #define HCILL_W4_DATA		4
  
  /* HCILL states */
  enum hcill_states_e {
  	HCILL_ASLEEP,
  	HCILL_ASLEEP_TO_AWAKE,
  	HCILL_AWAKE,
  	HCILL_AWAKE_TO_ASLEEP
  };
  
  struct hcill_cmd {
  	u8 cmd;
  } __packed;
  
  struct ll_struct {
  	unsigned long rx_state;
  	unsigned long rx_count;
  	struct sk_buff *rx_skb;
  	struct sk_buff_head txq;
  	spinlock_t hcill_lock;		/* HCILL state lock	*/
  	unsigned long hcill_state;	/* HCILL power state	*/
  	struct sk_buff_head tx_wait_q;	/* HCILL wait queue	*/
  };
  
  /*
   * Builds and sends an HCILL command packet.
   * These are very simple packets with only 1 cmd byte
   */
  static int send_hcill_cmd(u8 cmd, struct hci_uart *hu)
  {
  	int err = 0;
  	struct sk_buff *skb = NULL;
  	struct ll_struct *ll = hu->priv;
  	struct hcill_cmd *hcill_packet;
  
  	BT_DBG("hu %p cmd 0x%x", hu, cmd);
  
  	/* allocate packet */
  	skb = bt_skb_alloc(1, GFP_ATOMIC);
  	if (!skb) {
  		BT_ERR("cannot allocate memory for HCILL packet");
  		err = -ENOMEM;
  		goto out;
  	}
  
  	/* prepare packet */
  	hcill_packet = (struct hcill_cmd *) skb_put(skb, 1);
  	hcill_packet->cmd = cmd;
  
  	/* send packet */
  	skb_queue_tail(&ll->txq, skb);
  out:
  	return err;
  }
  
  /* Initialize protocol */
  static int ll_open(struct hci_uart *hu)
  {
  	struct ll_struct *ll;
  
  	BT_DBG("hu %p", hu);
  
  	ll = kzalloc(sizeof(*ll), GFP_KERNEL);
  	if (!ll)
  		return -ENOMEM;
  
  	skb_queue_head_init(&ll->txq);
  	skb_queue_head_init(&ll->tx_wait_q);
  	spin_lock_init(&ll->hcill_lock);
  
  	ll->hcill_state = HCILL_AWAKE;
  
  	hu->priv = ll;
  
  	return 0;
  }
  
  /* Flush protocol data */
  static int ll_flush(struct hci_uart *hu)
  {
  	struct ll_struct *ll = hu->priv;
  
  	BT_DBG("hu %p", hu);
  
  	skb_queue_purge(&ll->tx_wait_q);
  	skb_queue_purge(&ll->txq);
  
  	return 0;
  }
  
  /* Close protocol */
  static int ll_close(struct hci_uart *hu)
  {
  	struct ll_struct *ll = hu->priv;
  
  	BT_DBG("hu %p", hu);
  
  	skb_queue_purge(&ll->tx_wait_q);
  	skb_queue_purge(&ll->txq);
  
  	kfree_skb(ll->rx_skb);
  
  	hu->priv = NULL;
  
  	kfree(ll);
  
  	return 0;
  }
  
  /*
   * internal function, which does common work of the device wake up process:
   * 1. places all pending packets (waiting in tx_wait_q list) in txq list.
   * 2. changes internal state to HCILL_AWAKE.
   * Note: assumes that hcill_lock spinlock is taken,
   * shouldn't be called otherwise!
   */
  static void __ll_do_awake(struct ll_struct *ll)
  {
  	struct sk_buff *skb = NULL;
  
  	while ((skb = skb_dequeue(&ll->tx_wait_q)))
  		skb_queue_tail(&ll->txq, skb);
  
  	ll->hcill_state = HCILL_AWAKE;
  }
  
  /*
   * Called upon a wake-up-indication from the device
   */
  static void ll_device_want_to_wakeup(struct hci_uart *hu)
  {
  	unsigned long flags;
  	struct ll_struct *ll = hu->priv;
  
  	BT_DBG("hu %p", hu);
  
  	/* lock hcill state */
  	spin_lock_irqsave(&ll->hcill_lock, flags);
  
  	switch (ll->hcill_state) {
  	case HCILL_ASLEEP_TO_AWAKE:
  		/*
  		 * This state means that both the host and the BRF chip
  		 * have simultaneously sent a wake-up-indication packet.
  		 * Traditionally, in this case, receiving a wake-up-indication
  		 * was enough and an additional wake-up-ack wasn't needed.
  		 * This has changed with the BRF6350, which does require an
  		 * explicit wake-up-ack. Other BRF versions, which do not
  		 * require an explicit ack here, do accept it, thus it is
  		 * perfectly safe to always send one.
  		 */
  		BT_DBG("dual wake-up-indication");
  		/* deliberate fall-through - do not add break */
  	case HCILL_ASLEEP:
  		/* acknowledge device wake up */
  		if (send_hcill_cmd(HCILL_WAKE_UP_ACK, hu) < 0) {
  			BT_ERR("cannot acknowledge device wake up");
  			goto out;
  		}
  		break;
  	default:
  		/* any other state is illegal */
  		BT_ERR("received HCILL_WAKE_UP_IND in state %ld", ll->hcill_state);
  		break;
  	}
  
  	/* send pending packets and change state to HCILL_AWAKE */
  	__ll_do_awake(ll);
  
  out:
  	spin_unlock_irqrestore(&ll->hcill_lock, flags);
  
  	/* actually send the packets */
  	hci_uart_tx_wakeup(hu);
  }
  
  /*
   * Called upon a sleep-indication from the device
   */
  static void ll_device_want_to_sleep(struct hci_uart *hu)
  {
  	unsigned long flags;
  	struct ll_struct *ll = hu->priv;
  
  	BT_DBG("hu %p", hu);
  
  	/* lock hcill state */
  	spin_lock_irqsave(&ll->hcill_lock, flags);
  
  	/* sanity check */
  	if (ll->hcill_state != HCILL_AWAKE)
  		BT_ERR("ERR: HCILL_GO_TO_SLEEP_IND in state %ld", ll->hcill_state);
  
  	/* acknowledge device sleep */
  	if (send_hcill_cmd(HCILL_GO_TO_SLEEP_ACK, hu) < 0) {
  		BT_ERR("cannot acknowledge device sleep");
  		goto out;
  	}
  
  	/* update state */
  	ll->hcill_state = HCILL_ASLEEP;
  
  out:
  	spin_unlock_irqrestore(&ll->hcill_lock, flags);
  
  	/* actually send the sleep ack packet */
  	hci_uart_tx_wakeup(hu);
  }
  
  /*
   * Called upon wake-up-acknowledgement from the device
   */
  static void ll_device_woke_up(struct hci_uart *hu)
  {
  	unsigned long flags;
  	struct ll_struct *ll = hu->priv;
  
  	BT_DBG("hu %p", hu);
  
  	/* lock hcill state */
  	spin_lock_irqsave(&ll->hcill_lock, flags);
  
  	/* sanity check */
  	if (ll->hcill_state != HCILL_ASLEEP_TO_AWAKE)
  		BT_ERR("received HCILL_WAKE_UP_ACK in state %ld", ll->hcill_state);
  
  	/* send pending packets and change state to HCILL_AWAKE */
  	__ll_do_awake(ll);
  
  	spin_unlock_irqrestore(&ll->hcill_lock, flags);
  
  	/* actually send the packets */
  	hci_uart_tx_wakeup(hu);
  }
  
  /* Enqueue frame for transmittion (padding, crc, etc) */
  /* may be called from two simultaneous tasklets */
  static int ll_enqueue(struct hci_uart *hu, struct sk_buff *skb)
  {
  	unsigned long flags = 0;
  	struct ll_struct *ll = hu->priv;
  
  	BT_DBG("hu %p skb %p", hu, skb);
  
  	/* Prepend skb with frame type */
  	memcpy(skb_push(skb, 1), &bt_cb(skb)->pkt_type, 1);
  
  	/* lock hcill state */
  	spin_lock_irqsave(&ll->hcill_lock, flags);
  
  	/* act according to current state */
  	switch (ll->hcill_state) {
  	case HCILL_AWAKE:
  		BT_DBG("device awake, sending normally");
  		skb_queue_tail(&ll->txq, skb);
  		break;
  	case HCILL_ASLEEP:
  		BT_DBG("device asleep, waking up and queueing packet");
  		/* save packet for later */
  		skb_queue_tail(&ll->tx_wait_q, skb);
  		/* awake device */
  		if (send_hcill_cmd(HCILL_WAKE_UP_IND, hu) < 0) {
  			BT_ERR("cannot wake up device");
  			break;
  		}
  		ll->hcill_state = HCILL_ASLEEP_TO_AWAKE;
  		break;
  	case HCILL_ASLEEP_TO_AWAKE:
  		BT_DBG("device waking up, queueing packet");
  		/* transient state; just keep packet for later */
  		skb_queue_tail(&ll->tx_wait_q, skb);
  		break;
  	default:
  		BT_ERR("illegal hcill state: %ld (losing packet)", ll->hcill_state);
  		kfree_skb(skb);
  		break;
  	}
  
  	spin_unlock_irqrestore(&ll->hcill_lock, flags);
  
  	return 0;
  }
  
  static inline int ll_check_data_len(struct hci_dev *hdev, struct ll_struct *ll, int len)
  {
  	int room = skb_tailroom(ll->rx_skb);
  
  	BT_DBG("len %d room %d", len, room);
  
  	if (!len) {
  		hci_recv_frame(hdev, ll->rx_skb);
  	} else if (len > room) {
  		BT_ERR("Data length is too large");
  		kfree_skb(ll->rx_skb);
  	} else {
  		ll->rx_state = HCILL_W4_DATA;
  		ll->rx_count = len;
  		return len;
  	}
  
  	ll->rx_state = HCILL_W4_PACKET_TYPE;
  	ll->rx_skb   = NULL;
  	ll->rx_count = 0;
  
  	return 0;
  }
  
  /* Recv data */
  static int ll_recv(struct hci_uart *hu, void *data, int count)
  {
  	struct ll_struct *ll = hu->priv;
  	char *ptr;
  	struct hci_event_hdr *eh;
  	struct hci_acl_hdr   *ah;
  	struct hci_sco_hdr   *sh;
  	int len, type, dlen;
  
  	BT_DBG("hu %p count %d rx_state %ld rx_count %ld", hu, count, ll->rx_state, ll->rx_count);
  
  	ptr = data;
  	while (count) {
  		if (ll->rx_count) {
  			len = min_t(unsigned int, ll->rx_count, count);
  			memcpy(skb_put(ll->rx_skb, len), ptr, len);
  			ll->rx_count -= len; count -= len; ptr += len;
  
  			if (ll->rx_count)
  				continue;
  
  			switch (ll->rx_state) {
  			case HCILL_W4_DATA:
  				BT_DBG("Complete data");
  				hci_recv_frame(hu->hdev, ll->rx_skb);
  
  				ll->rx_state = HCILL_W4_PACKET_TYPE;
  				ll->rx_skb = NULL;
  				continue;
  
  			case HCILL_W4_EVENT_HDR:
  				eh = hci_event_hdr(ll->rx_skb);
  
  				BT_DBG("Event header: evt 0x%2.2x plen %d", eh->evt, eh->plen);
  
  				ll_check_data_len(hu->hdev, ll, eh->plen);
  				continue;
  
  			case HCILL_W4_ACL_HDR:
  				ah = hci_acl_hdr(ll->rx_skb);
  				dlen = __le16_to_cpu(ah->dlen);
  
  				BT_DBG("ACL header: dlen %d", dlen);
  
  				ll_check_data_len(hu->hdev, ll, dlen);
  				continue;
  
  			case HCILL_W4_SCO_HDR:
  				sh = hci_sco_hdr(ll->rx_skb);
  
  				BT_DBG("SCO header: dlen %d", sh->dlen);
  
  				ll_check_data_len(hu->hdev, ll, sh->dlen);
  				continue;
  			}
  		}
  
  		/* HCILL_W4_PACKET_TYPE */
  		switch (*ptr) {
  		case HCI_EVENT_PKT:
  			BT_DBG("Event packet");
  			ll->rx_state = HCILL_W4_EVENT_HDR;
  			ll->rx_count = HCI_EVENT_HDR_SIZE;
  			type = HCI_EVENT_PKT;
  			break;
  
  		case HCI_ACLDATA_PKT:
  			BT_DBG("ACL packet");
  			ll->rx_state = HCILL_W4_ACL_HDR;
  			ll->rx_count = HCI_ACL_HDR_SIZE;
  			type = HCI_ACLDATA_PKT;
  			break;
  
  		case HCI_SCODATA_PKT:
  			BT_DBG("SCO packet");
  			ll->rx_state = HCILL_W4_SCO_HDR;
  			ll->rx_count = HCI_SCO_HDR_SIZE;
  			type = HCI_SCODATA_PKT;
  			break;
  
  		/* HCILL signals */
  		case HCILL_GO_TO_SLEEP_IND:
  			BT_DBG("HCILL_GO_TO_SLEEP_IND packet");
  			ll_device_want_to_sleep(hu);
  			ptr++; count--;
  			continue;
  
  		case HCILL_GO_TO_SLEEP_ACK:
  			/* shouldn't happen */
  			BT_ERR("received HCILL_GO_TO_SLEEP_ACK (in state %ld)", ll->hcill_state);
  			ptr++; count--;
  			continue;
  
  		case HCILL_WAKE_UP_IND:
  			BT_DBG("HCILL_WAKE_UP_IND packet");
  			ll_device_want_to_wakeup(hu);
  			ptr++; count--;
  			continue;
  
  		case HCILL_WAKE_UP_ACK:
  			BT_DBG("HCILL_WAKE_UP_ACK packet");
  			ll_device_woke_up(hu);
  			ptr++; count--;
  			continue;
  
  		default:
  			BT_ERR("Unknown HCI packet type %2.2x", (__u8)*ptr);
  			hu->hdev->stat.err_rx++;
  			ptr++; count--;
  			continue;
  		}
  
  		ptr++; count--;
  
  		/* Allocate packet */
  		ll->rx_skb = bt_skb_alloc(HCI_MAX_FRAME_SIZE, GFP_ATOMIC);
  		if (!ll->rx_skb) {
  			BT_ERR("Can't allocate mem for new packet");
  			ll->rx_state = HCILL_W4_PACKET_TYPE;
  			ll->rx_count = 0;
  			return -ENOMEM;
  		}
  
  		bt_cb(ll->rx_skb)->pkt_type = type;
  	}
  
  	return count;
  }
  
  static struct sk_buff *ll_dequeue(struct hci_uart *hu)
  {
  	struct ll_struct *ll = hu->priv;
  	return skb_dequeue(&ll->txq);
  }
  
  static struct hci_uart_proto llp = {
  	.id		= HCI_UART_LL,
  	.open		= ll_open,
  	.close		= ll_close,
  	.recv		= ll_recv,
  	.enqueue	= ll_enqueue,
  	.dequeue	= ll_dequeue,
  	.flush		= ll_flush,
  };
  
  int __init ll_init(void)
  {
  	int err = hci_uart_register_proto(&llp);
  
  	if (!err)
  		BT_INFO("HCILL protocol initialized");
  	else
  		BT_ERR("HCILL protocol registration failed");
  
  	return err;
  }
  
  int __exit ll_deinit(void)
  {
  	return hci_uart_unregister_proto(&llp);
  }