/*
   * Device handling thread implementation for mac80211 ST-Ericsson CW1200 drivers
   *
   * Copyright (c) 2010, ST-Ericsson
   * Author: Dmitry Tarnyagin <dmitry.tarnyagin@lockless.no>
   *
   * Based on:
   * ST-Ericsson UMAC CW1200 driver, which is
   * Copyright (c) 2010, ST-Ericsson
   * Author: Ajitpal Singh <ajitpal.singh@stericsson.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.
   */
  
  #include <linux/module.h>
  #include <net/mac80211.h>
  #include <linux/kthread.h>
  #include <linux/timer.h>
  
  #include "cw1200.h"
  #include "bh.h"
  #include "hwio.h"
  #include "wsm.h"
  #include "hwbus.h"
  #include "debug.h"
  #include "fwio.h"
  
  static int cw1200_bh(void *arg);
  
  #define DOWNLOAD_BLOCK_SIZE_WR	(0x1000 - 4)
  /* an SPI message cannot be bigger than (2"12-1)*2 bytes
   * "*2" to cvt to bytes
   */
  #define MAX_SZ_RD_WR_BUFFERS	(DOWNLOAD_BLOCK_SIZE_WR*2)
  #define PIGGYBACK_CTRL_REG	(2)
  #define EFFECTIVE_BUF_SIZE	(MAX_SZ_RD_WR_BUFFERS - PIGGYBACK_CTRL_REG)
  
  /* Suspend state privates */
  enum cw1200_bh_pm_state {
  	CW1200_BH_RESUMED = 0,
  	CW1200_BH_SUSPEND,
  	CW1200_BH_SUSPENDED,
  	CW1200_BH_RESUME,
  };
  
  typedef int (*cw1200_wsm_handler)(struct cw1200_common *priv,
  	u8 *data, size_t size);
  
  static void cw1200_bh_work(struct work_struct *work)
  {
  	struct cw1200_common *priv =
  	container_of(work, struct cw1200_common, bh_work);
  	cw1200_bh(priv);
  }
  
  int cw1200_register_bh(struct cw1200_common *priv)
  {
  	int err = 0;
  	/* Realtime workqueue */
  	priv->bh_workqueue = alloc_workqueue("cw1200_bh",
  				WQ_MEM_RECLAIM | WQ_HIGHPRI
  				| WQ_CPU_INTENSIVE, 1);
  
  	if (!priv->bh_workqueue)
  		return -ENOMEM;
  
  	INIT_WORK(&priv->bh_work, cw1200_bh_work);
  
  	pr_debug("[BH] register.
  ");
  
  	atomic_set(&priv->bh_rx, 0);
  	atomic_set(&priv->bh_tx, 0);
  	atomic_set(&priv->bh_term, 0);
  	atomic_set(&priv->bh_suspend, CW1200_BH_RESUMED);
  	priv->bh_error = 0;
  	priv->hw_bufs_used = 0;
  	priv->buf_id_tx = 0;
  	priv->buf_id_rx = 0;
  	init_waitqueue_head(&priv->bh_wq);
  	init_waitqueue_head(&priv->bh_evt_wq);
  
  	err = !queue_work(priv->bh_workqueue, &priv->bh_work);
  	WARN_ON(err);
  	return err;
  }
  
  void cw1200_unregister_bh(struct cw1200_common *priv)
  {
  	atomic_add(1, &priv->bh_term);
  	wake_up(&priv->bh_wq);
  
  	flush_workqueue(priv->bh_workqueue);
  
  	destroy_workqueue(priv->bh_workqueue);
  	priv->bh_workqueue = NULL;
  
  	pr_debug("[BH] unregistered.
  ");
  }
  
  void cw1200_irq_handler(struct cw1200_common *priv)
  {
  	pr_debug("[BH] irq.
  ");
  
  	/* Disable Interrupts! */
  	/* NOTE:  hwbus_ops->lock already held */
  	__cw1200_irq_enable(priv, 0);
  
  	if (/* WARN_ON */(priv->bh_error))
  		return;
  
  	if (atomic_add_return(1, &priv->bh_rx) == 1)
  		wake_up(&priv->bh_wq);
  }
  EXPORT_SYMBOL_GPL(cw1200_irq_handler);
  
  void cw1200_bh_wakeup(struct cw1200_common *priv)
  {
  	pr_debug("[BH] wakeup.
  ");
  	if (priv->bh_error) {
  		pr_err("[BH] wakeup failed (BH error)
  ");
  		return;
  	}
  
  	if (atomic_add_return(1, &priv->bh_tx) == 1)
  		wake_up(&priv->bh_wq);
  }
  
  int cw1200_bh_suspend(struct cw1200_common *priv)
  {
  	pr_debug("[BH] suspend.
  ");
  	if (priv->bh_error) {
  		wiphy_warn(priv->hw->wiphy, "BH error -- can't suspend
  ");
  		return -EINVAL;
  	}
  
  	atomic_set(&priv->bh_suspend, CW1200_BH_SUSPEND);
  	wake_up(&priv->bh_wq);
  	return wait_event_timeout(priv->bh_evt_wq, priv->bh_error ||
  		(CW1200_BH_SUSPENDED == atomic_read(&priv->bh_suspend)),
  		 1 * HZ) ? 0 : -ETIMEDOUT;
  }
  
  int cw1200_bh_resume(struct cw1200_common *priv)
  {
  	pr_debug("[BH] resume.
  ");
  	if (priv->bh_error) {
  		wiphy_warn(priv->hw->wiphy, "BH error -- can't resume
  ");
  		return -EINVAL;
  	}
  
  	atomic_set(&priv->bh_suspend, CW1200_BH_RESUME);
  	wake_up(&priv->bh_wq);
  	return wait_event_timeout(priv->bh_evt_wq, priv->bh_error ||
  		(CW1200_BH_RESUMED == atomic_read(&priv->bh_suspend)),
  		1 * HZ) ? 0 : -ETIMEDOUT;
  }
  
  static inline void wsm_alloc_tx_buffer(struct cw1200_common *priv)
  {
  	++priv->hw_bufs_used;
  }
  
  int wsm_release_tx_buffer(struct cw1200_common *priv, int count)
  {
  	int ret = 0;
  	int hw_bufs_used = priv->hw_bufs_used;
  
  	priv->hw_bufs_used -= count;
  	if (WARN_ON(priv->hw_bufs_used < 0))
  		ret = -1;
  	else if (hw_bufs_used >= priv->wsm_caps.input_buffers)
  		ret = 1;
  	if (!priv->hw_bufs_used)
  		wake_up(&priv->bh_evt_wq);
  	return ret;
  }
  
  static int cw1200_bh_read_ctrl_reg(struct cw1200_common *priv,
  					  u16 *ctrl_reg)
  {
  	int ret;
  
  	ret = cw1200_reg_read_16(priv,
  			ST90TDS_CONTROL_REG_ID, ctrl_reg);
  	if (ret) {
  		ret = cw1200_reg_read_16(priv,
  				ST90TDS_CONTROL_REG_ID, ctrl_reg);
  		if (ret)
  			pr_err("[BH] Failed to read control register.
  ");
  	}
  
  	return ret;
  }
  
  static int cw1200_device_wakeup(struct cw1200_common *priv)
  {
  	u16 ctrl_reg;
  	int ret;
  
  	pr_debug("[BH] Device wakeup.
  ");
  
  	/* First, set the dpll register */
  	ret = cw1200_reg_write_32(priv, ST90TDS_TSET_GEN_R_W_REG_ID,
  				  cw1200_dpll_from_clk(priv->hw_refclk));
  	if (WARN_ON(ret))
  		return ret;
  
  	/* To force the device to be always-on, the host sets WLAN_UP to 1 */
  	ret = cw1200_reg_write_16(priv, ST90TDS_CONTROL_REG_ID,
  			ST90TDS_CONT_WUP_BIT);
  	if (WARN_ON(ret))
  		return ret;
  
  	ret = cw1200_bh_read_ctrl_reg(priv, &ctrl_reg);
  	if (WARN_ON(ret))
  		return ret;
  
  	/* If the device returns WLAN_RDY as 1, the device is active and will
  	 * remain active.
  	 */
  	if (ctrl_reg & ST90TDS_CONT_RDY_BIT) {
  		pr_debug("[BH] Device awake.
  ");
  		return 1;
  	}
  
  	return 0;
  }
  
  /* Must be called from BH thraed. */
  void cw1200_enable_powersave(struct cw1200_common *priv,
  			     bool enable)
  {
  	pr_debug("[BH] Powerave is %s.
  ",
  		 enable ? "enabled" : "disabled");
  	priv->powersave_enabled = enable;
  }
  
  static int cw1200_bh_rx_helper(struct cw1200_common *priv,
  			       uint16_t *ctrl_reg,
  			       int *tx)
  {
  	size_t read_len = 0;
  	struct sk_buff *skb_rx = NULL;
  	struct wsm_hdr *wsm;
  	size_t wsm_len;
  	u16 wsm_id;
  	u8 wsm_seq;
  	int rx_resync = 1;
  
  	size_t alloc_len;
  	u8 *data;
  
  	read_len = (*ctrl_reg & ST90TDS_CONT_NEXT_LEN_MASK) * 2;
  	if (!read_len)
  		return 0; /* No more work */
  
  	if (WARN_ON((read_len < sizeof(struct wsm_hdr)) ||
  		    (read_len > EFFECTIVE_BUF_SIZE))) {
  		pr_debug("Invalid read len: %zu (%04x)",
  			 read_len, *ctrl_reg);
  		goto err;
  	}
  
  	/* Add SIZE of PIGGYBACK reg (CONTROL Reg)
  	 * to the NEXT Message length + 2 Bytes for SKB
  	 */
  	read_len = read_len + 2;
  
  	alloc_len = priv->hwbus_ops->align_size(
  		priv->hwbus_priv, read_len);
  
  	/* Check if not exceeding CW1200 capabilities */
  	if (WARN_ON_ONCE(alloc_len > EFFECTIVE_BUF_SIZE)) {
  		pr_debug("Read aligned len: %zu
  ",
  			 alloc_len);
  	}
  
  	skb_rx = dev_alloc_skb(alloc_len);
  	if (WARN_ON(!skb_rx))
  		goto err;
  
  	skb_trim(skb_rx, 0);
  	skb_put(skb_rx, read_len);
  	data = skb_rx->data;
  	if (WARN_ON(!data))
  		goto err;
  
  	if (WARN_ON(cw1200_data_read(priv, data, alloc_len))) {
  		pr_err("rx blew up, len %zu
  ", alloc_len);
  		goto err;
  	}
  
  	/* Piggyback */
  	*ctrl_reg = __le16_to_cpu(
  		((__le16 *)data)[alloc_len / 2 - 1]);
  
  	wsm = (struct wsm_hdr *)data;
  	wsm_len = __le16_to_cpu(wsm->len);
  	if (WARN_ON(wsm_len > read_len))
  		goto err;
  
  	if (priv->wsm_enable_wsm_dumps)
  		print_hex_dump_bytes("<-- ",
  				     DUMP_PREFIX_NONE,
  				     data, wsm_len);
  
  	wsm_id  = __le16_to_cpu(wsm->id) & 0xFFF;
  	wsm_seq = (__le16_to_cpu(wsm->id) >> 13) & 7;
  
  	skb_trim(skb_rx, wsm_len);
  
  	if (wsm_id == 0x0800) {
  		wsm_handle_exception(priv,
  				     &data[sizeof(*wsm)],
  				     wsm_len - sizeof(*wsm));
  		goto err;
  	} else if (!rx_resync) {
  		if (WARN_ON(wsm_seq != priv->wsm_rx_seq))
  			goto err;
  	}
  	priv->wsm_rx_seq = (wsm_seq + 1) & 7;
  	rx_resync = 0;
  
  	if (wsm_id & 0x0400) {
  		int rc = wsm_release_tx_buffer(priv, 1);
  		if (WARN_ON(rc < 0))
  			return rc;
  		else if (rc > 0)
  			*tx = 1;
  	}
  
  	/* cw1200_wsm_rx takes care on SKB livetime */
  	if (WARN_ON(wsm_handle_rx(priv, wsm_id, wsm, &skb_rx)))
  		goto err;
  
  	if (skb_rx) {
  		dev_kfree_skb(skb_rx);
  		skb_rx = NULL;
  	}
  
  	return 0;
  
  err:
  	if (skb_rx) {
  		dev_kfree_skb(skb_rx);
  		skb_rx = NULL;
  	}
  	return -1;
  }
  
  static int cw1200_bh_tx_helper(struct cw1200_common *priv,
  			       int *pending_tx,
  			       int *tx_burst)
  {
  	size_t tx_len;
  	u8 *data;
  	int ret;
  	struct wsm_hdr *wsm;
  
  	if (priv->device_can_sleep) {
  		ret = cw1200_device_wakeup(priv);
  		if (WARN_ON(ret < 0)) { /* Error in wakeup */
  			*pending_tx = 1;
  			return 0;
  		} else if (ret) { /* Woke up */
  			priv->device_can_sleep = false;
  		} else { /* Did not awake */
  			*pending_tx = 1;
  			return 0;
  		}
  	}
  
  	wsm_alloc_tx_buffer(priv);
  	ret = wsm_get_tx(priv, &data, &tx_len, tx_burst);
  	if (ret <= 0) {
  		wsm_release_tx_buffer(priv, 1);
  		if (WARN_ON(ret < 0))
  			return ret; /* Error */
  		return 0; /* No work */
  	}
  
  	wsm = (struct wsm_hdr *)data;
  	BUG_ON(tx_len < sizeof(*wsm));
  	BUG_ON(__le16_to_cpu(wsm->len) != tx_len);
  
  	atomic_add(1, &priv->bh_tx);
  
  	tx_len = priv->hwbus_ops->align_size(
  		priv->hwbus_priv, tx_len);
  
  	/* Check if not exceeding CW1200 capabilities */
  	if (WARN_ON_ONCE(tx_len > EFFECTIVE_BUF_SIZE))
  		pr_debug("Write aligned len: %zu
  ", tx_len);
  
  	wsm->id &= __cpu_to_le16(0xffff ^ WSM_TX_SEQ(WSM_TX_SEQ_MAX));
  	wsm->id |= __cpu_to_le16(WSM_TX_SEQ(priv->wsm_tx_seq));
  
  	if (WARN_ON(cw1200_data_write(priv, data, tx_len))) {
  		pr_err("tx blew up, len %zu
  ", tx_len);
  		wsm_release_tx_buffer(priv, 1);
  		return -1; /* Error */
  	}
  
  	if (priv->wsm_enable_wsm_dumps)
  		print_hex_dump_bytes("--> ",
  				     DUMP_PREFIX_NONE,
  				     data,
  				     __le16_to_cpu(wsm->len));
  
  	wsm_txed(priv, data);
  	priv->wsm_tx_seq = (priv->wsm_tx_seq + 1) & WSM_TX_SEQ_MAX;
  
  	if (*tx_burst > 1) {
  		cw1200_debug_tx_burst(priv);
  		return 1; /* Work remains */
  	}
  
  	return 0;
  }
  
  static int cw1200_bh(void *arg)
  {
  	struct cw1200_common *priv = arg;
  	int rx, tx, term, suspend;
  	u16 ctrl_reg = 0;
  	int tx_allowed;
  	int pending_tx = 0;
  	int tx_burst;
  	long status;
  	u32 dummy;
  	int ret;
  
  	for (;;) {
  		if (!priv->hw_bufs_used &&
  		    priv->powersave_enabled &&
  		    !priv->device_can_sleep &&
  		    !atomic_read(&priv->recent_scan)) {
  			status = 1 * HZ;
  			pr_debug("[BH] Device wakedown. No data.
  ");
  			cw1200_reg_write_16(priv, ST90TDS_CONTROL_REG_ID, 0);
  			priv->device_can_sleep = true;
  		} else if (priv->hw_bufs_used) {
  			/* Interrupt loss detection */
  			status = 1 * HZ;
  		} else {
  			status = MAX_SCHEDULE_TIMEOUT;
  		}
  
  		/* Dummy Read for SDIO retry mechanism*/
  		if ((priv->hw_type != -1) &&
  		    (atomic_read(&priv->bh_rx) == 0) &&
  		    (atomic_read(&priv->bh_tx) == 0))
  			cw1200_reg_read(priv, ST90TDS_CONFIG_REG_ID,
  					&dummy, sizeof(dummy));
  
  		pr_debug("[BH] waiting ...
  ");
  		status = wait_event_interruptible_timeout(priv->bh_wq, ({
  				rx = atomic_xchg(&priv->bh_rx, 0);
  				tx = atomic_xchg(&priv->bh_tx, 0);
  				term = atomic_xchg(&priv->bh_term, 0);
  				suspend = pending_tx ?
  					0 : atomic_read(&priv->bh_suspend);
  				(rx || tx || term || suspend || priv->bh_error);
  			}), status);
  
  		pr_debug("[BH] - rx: %d, tx: %d, term: %d, bh_err: %d, suspend: %d, status: %ld
  ",
  			 rx, tx, term, suspend, priv->bh_error, status);
  
  		/* Did an error occur? */
  		if ((status < 0 && status != -ERESTARTSYS) ||
  		    term || priv->bh_error) {
  			break;
  		}
  		if (!status) {  /* wait_event timed out */
  			unsigned long timestamp = jiffies;
  			long timeout;
  			int pending = 0;
  			int i;
  
  			/* Check to see if we have any outstanding frames */
  			if (priv->hw_bufs_used && (!rx || !tx)) {
  				wiphy_warn(priv->hw->wiphy,
  					   "Missed interrupt? (%d frames outstanding)
  ",
  					   priv->hw_bufs_used);
  				rx = 1;
  
  				/* Get a timestamp of "oldest" frame */
  				for (i = 0; i < 4; ++i)
  					pending += cw1200_queue_get_xmit_timestamp(
  						&priv->tx_queue[i],
  						&timestamp,
  						priv->pending_frame_id);
  
  				/* Check if frame transmission is timed out.
  				 * Add an extra second with respect to possible
  				 * interrupt loss.
  				 */
  				timeout = timestamp +
  					WSM_CMD_LAST_CHANCE_TIMEOUT +
  					1 * HZ  -
  					jiffies;
  
  				/* And terminate BH thread if the frame is "stuck" */
  				if (pending && timeout < 0) {
  					wiphy_warn(priv->hw->wiphy,
  						   "Timeout waiting for TX confirm (%d/%d pending, %ld vs %lu).
  ",
  						   priv->hw_bufs_used, pending,
  						   timestamp, jiffies);
  					break;
  				}
  			} else if (!priv->device_can_sleep &&
  				   !atomic_read(&priv->recent_scan)) {
  				pr_debug("[BH] Device wakedown. Timeout.
  ");
  				cw1200_reg_write_16(priv,
  						    ST90TDS_CONTROL_REG_ID, 0);
  				priv->device_can_sleep = true;
  			}
  			goto done;
  		} else if (suspend) {
  			pr_debug("[BH] Device suspend.
  ");
  			if (priv->powersave_enabled) {
  				pr_debug("[BH] Device wakedown. Suspend.
  ");
  				cw1200_reg_write_16(priv,
  						    ST90TDS_CONTROL_REG_ID, 0);
  				priv->device_can_sleep = true;
  			}
  
  			atomic_set(&priv->bh_suspend, CW1200_BH_SUSPENDED);
  			wake_up(&priv->bh_evt_wq);
  			status = wait_event_interruptible(priv->bh_wq,
  							  CW1200_BH_RESUME == atomic_read(&priv->bh_suspend));
  			if (status < 0) {
  				wiphy_err(priv->hw->wiphy,
  					  "Failed to wait for resume: %ld.
  ",
  					  status);
  				break;
  			}
  			pr_debug("[BH] Device resume.
  ");
  			atomic_set(&priv->bh_suspend, CW1200_BH_RESUMED);
  			wake_up(&priv->bh_evt_wq);
  			atomic_add(1, &priv->bh_rx);
  			goto done;
  		}
  
  	rx:
  		tx += pending_tx;
  		pending_tx = 0;
  
  		if (cw1200_bh_read_ctrl_reg(priv, &ctrl_reg))
  			break;
  
  		/* Don't bother trying to rx unless we have data to read */
  		if (ctrl_reg & ST90TDS_CONT_NEXT_LEN_MASK) {
  			ret = cw1200_bh_rx_helper(priv, &ctrl_reg, &tx);
  			if (ret < 0)
  				break;
  			/* Double up here if there's more data.. */
  			if (ctrl_reg & ST90TDS_CONT_NEXT_LEN_MASK) {
  				ret = cw1200_bh_rx_helper(priv, &ctrl_reg, &tx);
  				if (ret < 0)
  					break;
  			}
  		}
  
  	tx:
  		if (tx) {
  			tx = 0;
  
  			BUG_ON(priv->hw_bufs_used > priv->wsm_caps.input_buffers);
  			tx_burst = priv->wsm_caps.input_buffers - priv->hw_bufs_used;
  			tx_allowed = tx_burst > 0;
  
  			if (!tx_allowed) {
  				/* Buffers full.  Ensure we process tx
  				 * after we handle rx..
  				 */
  				pending_tx = tx;
  				goto done_rx;
  			}
  			ret = cw1200_bh_tx_helper(priv, &pending_tx, &tx_burst);
  			if (ret < 0)
  				break;
  			if (ret > 0) /* More to transmit */
  				tx = ret;
  
  			/* Re-read ctrl reg */
  			if (cw1200_bh_read_ctrl_reg(priv, &ctrl_reg))
  				break;
  		}
  
  	done_rx:
  		if (priv->bh_error)
  			break;
  		if (ctrl_reg & ST90TDS_CONT_NEXT_LEN_MASK)
  			goto rx;
  		if (tx)
  			goto tx;
  
  	done:
  		/* Re-enable device interrupts */
  		priv->hwbus_ops->lock(priv->hwbus_priv);
  		__cw1200_irq_enable(priv, 1);
  		priv->hwbus_ops->unlock(priv->hwbus_priv);
  	}
  
  	/* Explicitly disable device interrupts */
  	priv->hwbus_ops->lock(priv->hwbus_priv);
  	__cw1200_irq_enable(priv, 0);
  	priv->hwbus_ops->unlock(priv->hwbus_priv);
  
  	if (!term) {
  		pr_err("[BH] Fatal error, exiting.
  ");
  		priv->bh_error = 1;
  		/* TODO: schedule_work(recovery) */
  	}
  	return 0;
  }