// SPDX-License-Identifier: GPL-2.0-only
/*
 * Interrupt bottom half (BH).
 *
 * Copyright (c) 2017-2020, Silicon Laboratories, Inc.
 * Copyright (c) 2010, ST-Ericsson
 */
#include <linux/gpio/consumer.h>
#include <net/mac80211.h>

#include "bh.h"
#include "wfx.h"
#include "hwio.h"
#include "traces.h"
#include "hif_rx.h"
#include "hif_api_cmd.h"

static void device_wakeup(struct wfx_dev *wdev)
{
        int max_retry = 3;

        if (!wdev->pdata.gpio_wakeup)
                return;
        if (gpiod_get_value_cansleep(wdev->pdata.gpio_wakeup) > 0)
                return;

        if (wfx_api_older_than(wdev, 1, 4)) {
                gpiod_set_value_cansleep(wdev->pdata.gpio_wakeup, 1);
                if (!completion_done(&wdev->hif.ctrl_ready))
                        usleep_range(2000, 2500);
                return;
        }
        for (;;) {
                gpiod_set_value_cansleep(wdev->pdata.gpio_wakeup, 1);
                // completion.h does not provide any function to wait
                // completion without consume it (a kind of
                // wait_for_completion_done_timeout()). So we have to emulate
                // it.
                if (wait_for_completion_timeout(&wdev->hif.ctrl_ready,
                                                msecs_to_jiffies(2))) {
                        complete(&wdev->hif.ctrl_ready);
                        return;
                } else if (max_retry-- > 0) {
                        // Older firmwares have a race in sleep/wake-up process.
                        // Redo the process is sufficient to unfreeze the
                        // chip.
                        dev_err(wdev->dev, "timeout while wake up chip\n");
                        gpiod_set_value_cansleep(wdev->pdata.gpio_wakeup, 0);
                        usleep_range(2000, 2500);
                } else {
                        dev_err(wdev->dev, "max wake-up retries reached\n");
                        return;
                }
        }
}

static void device_release(struct wfx_dev *wdev)
{
        if (!wdev->pdata.gpio_wakeup)
                return;

        gpiod_set_value_cansleep(wdev->pdata.gpio_wakeup, 0);
}

static int rx_helper(struct wfx_dev *wdev, size_t read_len, int *is_cnf)
{
        struct sk_buff *skb;
        struct hif_msg *hif;
        size_t alloc_len;
        size_t computed_len;
        int release_count;
        int piggyback = 0;

        WARN(read_len > round_down(0xFFF, 2) * sizeof(u16),
             "%s: request exceed WFx capability", __func__);

        // Add 2 to take into account piggyback size
        alloc_len = wdev->hwbus_ops->align_size(wdev->hwbus_priv, read_len + 2);
        skb = dev_alloc_skb(alloc_len);
        if (!skb)
                return -ENOMEM;

        if (wfx_data_read(wdev, skb->data, alloc_len))
                goto err;

        piggyback = le16_to_cpup((__le16 *)(skb->data + alloc_len - 2));
        _trace_piggyback(piggyback, false);

        hif = (struct hif_msg *)skb->data;
        WARN(hif->encrypted & 0x3, "encryption is unsupported");
        if (WARN(read_len < sizeof(struct hif_msg), "corrupted read"))
                goto err;
        computed_len = le16_to_cpu(hif->len);
        computed_len = round_up(computed_len, 2);
        if (computed_len != read_len) {
                dev_err(wdev->dev, "inconsistent message length: %zu != %zu\n",
                        computed_len, read_len);
                print_hex_dump(KERN_INFO, "hif: ", DUMP_PREFIX_OFFSET, 16, 1,
                               hif, read_len, true);
                goto err;
        }

        if (!(hif->id & HIF_ID_IS_INDICATION)) {
                (*is_cnf)++;
                if (hif->id == HIF_CNF_ID_MULTI_TRANSMIT)
                        release_count = ((struct hif_cnf_multi_transmit *)hif->body)->num_tx_confs;
                else
                        release_count = 1;
                WARN(wdev->hif.tx_buffers_used < release_count, "corrupted buffer counter");
                wdev->hif.tx_buffers_used -= release_count;
        }
        _trace_hif_recv(hif, wdev->hif.tx_buffers_used);

        if (hif->id != HIF_IND_ID_EXCEPTION && hif->id != HIF_IND_ID_ERROR) {
                if (hif->seqnum != wdev->hif.rx_seqnum)
                        dev_warn(wdev->dev, "wrong message sequence: %d != %d\n",
                                 hif->seqnum, wdev->hif.rx_seqnum);
                wdev->hif.rx_seqnum = (hif->seqnum + 1) % (HIF_COUNTER_MAX + 1);
        }

        skb_put(skb, le16_to_cpu(hif->len));
        // wfx_handle_rx takes care on SKB livetime
        wfx_handle_rx(wdev, skb);
        if (!wdev->hif.tx_buffers_used)
                wake_up(&wdev->hif.tx_buffers_empty);

        return piggyback;

err:
        if (skb)
                dev_kfree_skb(skb);
        return -EIO;
}

static int bh_work_rx(struct wfx_dev *wdev, int max_msg, int *num_cnf)
{
        size_t len;
        int i;
        int ctrl_reg, piggyback;

        piggyback = 0;
        for (i = 0; i < max_msg; i++) {
                if (piggyback & CTRL_NEXT_LEN_MASK)
                        ctrl_reg = piggyback;
                else if (try_wait_for_completion(&wdev->hif.ctrl_ready))
                        ctrl_reg = atomic_xchg(&wdev->hif.ctrl_reg, 0);
                else
                        ctrl_reg = 0;
                if (!(ctrl_reg & CTRL_NEXT_LEN_MASK))
                        return i;
                // ctrl_reg units are 16bits words
                len = (ctrl_reg & CTRL_NEXT_LEN_MASK) * 2;
                piggyback = rx_helper(wdev, len, num_cnf);
                if (piggyback < 0)
                        return i;
                if (!(piggyback & CTRL_WLAN_READY))
                        dev_err(wdev->dev, "unexpected piggyback value: ready bit not set: %04x\n",
                                piggyback);
        }
        if (piggyback & CTRL_NEXT_LEN_MASK) {
                ctrl_reg = atomic_xchg(&wdev->hif.ctrl_reg, piggyback);
                complete(&wdev->hif.ctrl_ready);
                if (ctrl_reg)
                        dev_err(wdev->dev, "unexpected IRQ happened: %04x/%04x\n",
                                ctrl_reg, piggyback);
        }
        return i;
}

static void tx_helper(struct wfx_dev *wdev, struct hif_msg *hif)
{
        int ret;
        void *data;
        bool is_encrypted = false;
        size_t len = le16_to_cpu(hif->len);

        WARN(len < sizeof(*hif), "try to send corrupted data");

        hif->seqnum = wdev->hif.tx_seqnum;
        wdev->hif.tx_seqnum = (wdev->hif.tx_seqnum + 1) % (HIF_COUNTER_MAX + 1);

        data = hif;
        WARN(len > wdev->hw_caps.size_inp_ch_buf,
             "%s: request exceed WFx capability: %zu > %d\n", __func__,
             len, wdev->hw_caps.size_inp_ch_buf);
        len = wdev->hwbus_ops->align_size(wdev->hwbus_priv, len);
        ret = wfx_data_write(wdev, data, len);
        if (ret)
                goto end;

        wdev->hif.tx_buffers_used++;
        _trace_hif_send(hif, wdev->hif.tx_buffers_used);
end:
        if (is_encrypted)
                kfree(data);
}

static int bh_work_tx(struct wfx_dev *wdev, int max_msg)
{
        struct hif_msg *hif;
        int i;

        for (i = 0; i < max_msg; i++) {
                hif = NULL;
                if (wdev->hif.tx_buffers_used < wdev->hw_caps.num_inp_ch_bufs) {
                        if (try_wait_for_completion(&wdev->hif_cmd.ready)) {
                                WARN(!mutex_is_locked(&wdev->hif_cmd.lock), "data locking error");
                                hif = wdev->hif_cmd.buf_send;
                        } else {
                                hif = wfx_tx_queues_get(wdev);
                        }
                }
                if (!hif)
                        return i;
                tx_helper(wdev, hif);
        }
        return i;
}

/* In SDIO mode, it is necessary to make an access to a register to acknowledge
 * last received message. It could be possible to restrict this acknowledge to
 * SDIO mode and only if last operation was rx.
 */
static void ack_sdio_data(struct wfx_dev *wdev)
{
        u32 cfg_reg;

        config_reg_read(wdev, &cfg_reg);
        if (cfg_reg & 0xFF) {
                dev_warn(wdev->dev, "chip reports errors: %02x\n",
                         cfg_reg & 0xFF);
                config_reg_write_bits(wdev, 0xFF, 0x00);
        }
}

static void bh_work(struct work_struct *work)
{
        struct wfx_dev *wdev = container_of(work, struct wfx_dev, hif.bh);
        int stats_req = 0, stats_cnf = 0, stats_ind = 0;
        bool release_chip = false, last_op_is_rx = false;
        int num_tx, num_rx;

        device_wakeup(wdev);
        do {
                num_tx = bh_work_tx(wdev, 32);
                stats_req += num_tx;
                if (num_tx)
                        last_op_is_rx = false;
                num_rx = bh_work_rx(wdev, 32, &stats_cnf);
                stats_ind += num_rx;
                if (num_rx)
                        last_op_is_rx = true;
        } while (num_rx || num_tx);
        stats_ind -= stats_cnf;

        if (last_op_is_rx)
                ack_sdio_data(wdev);
        if (!wdev->hif.tx_buffers_used && !work_pending(work)) {
                device_release(wdev);
                release_chip = true;
        }
        _trace_bh_stats(stats_ind, stats_req, stats_cnf,
                        wdev->hif.tx_buffers_used, release_chip);
}

/*
 * An IRQ from chip did occur
 */
void wfx_bh_request_rx(struct wfx_dev *wdev)
{
        u32 cur, prev;

        control_reg_read(wdev, &cur);
        prev = atomic_xchg(&wdev->hif.ctrl_reg, cur);
        complete(&wdev->hif.ctrl_ready);
        queue_work(system_highpri_wq, &wdev->hif.bh);

        if (!(cur & CTRL_NEXT_LEN_MASK))
                dev_err(wdev->dev, "unexpected control register value: length field is 0: %04x\n",
                        cur);
        if (prev != 0)
                dev_err(wdev->dev, "received IRQ but previous data was not (yet) read: %04x/%04x\n",
                        prev, cur);
}

/*
 * Driver want to send data
 */
void wfx_bh_request_tx(struct wfx_dev *wdev)
{
        queue_work(system_highpri_wq, &wdev->hif.bh);
}

/*
 * If IRQ is not available, this function allow to manually poll the control
 * register and simulate an IRQ ahen an event happened.
 *
 * Note that the device has a bug: If an IRQ raise while host read control
 * register, the IRQ is lost. So, use this function carefully (only duing
 * device initialisation).
 */
void wfx_bh_poll_irq(struct wfx_dev *wdev)
{
        ktime_t now, start;
        u32 reg;

        WARN(!wdev->poll_irq, "unexpected IRQ polling can mask IRQ");
        start = ktime_get();
        for (;;) {
                control_reg_read(wdev, &reg);
                now = ktime_get();
                if (reg & 0xFFF)
                        break;
                if (ktime_after(now, ktime_add_ms(start, 1000))) {
                        dev_err(wdev->dev, "time out while polling control register\n");
                        return;
                }
                udelay(200);
        }
        wfx_bh_request_rx(wdev);
}

void wfx_bh_register(struct wfx_dev *wdev)
{
        INIT_WORK(&wdev->hif.bh, bh_work);
        init_completion(&wdev->hif.ctrl_ready);
        init_waitqueue_head(&wdev->hif.tx_buffers_empty);
}

void wfx_bh_unregister(struct wfx_dev *wdev)
{
        flush_work(&wdev->hif.bh);
}