/*
 * 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.\n");

        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.\n");
}

void cw1200_irq_handler(struct cw1200_common *priv)
{
        pr_debug("[BH] irq.\n");

        /* 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.\n");
        if (priv->bh_error) {
                pr_err("[BH] wakeup failed (BH error)\n");
                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.\n");
        if (priv->bh_error) {
                wiphy_warn(priv->hw->wiphy, "BH error -- can't suspend\n");
                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.\n");
        if (priv->bh_error) {
                wiphy_warn(priv->hw->wiphy, "BH error -- can't resume\n");
                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.\n");
        }

        return ret;
}

static int cw1200_device_wakeup(struct cw1200_common *priv)
{
        u16 ctrl_reg;
        int ret;

        pr_debug("[BH] Device wakeup.\n");

        /* 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.\n");
                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.\n",
                 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\n",
                         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\n", 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\n", 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\n", 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.\n");
                        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 ...\n");
                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\n",
                         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)\n",
                                           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).\n",
                                                   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.\n");
                                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.\n");
                        if (priv->powersave_enabled) {
                                pr_debug("[BH] Device wakedown. Suspend.\n");
                                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.\n",
                                          status);
                                break;
                        }
                        pr_debug("[BH] Device resume.\n");
                        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.\n");
                priv->bh_error = 1;
                /* TODO: schedule_work(recovery) */
        }
        return 0;
}