linux/drivers/net/wireless/broadcom/b43/phy_common.c
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   1/*
   2
   3  Broadcom B43 wireless driver
   4  Common PHY routines
   5
   6  Copyright (c) 2005 Martin Langer <martin-langer@gmx.de>,
   7  Copyright (c) 2005-2007 Stefano Brivio <stefano.brivio@polimi.it>
   8  Copyright (c) 2005-2008 Michael Buesch <m@bues.ch>
   9  Copyright (c) 2005, 2006 Danny van Dyk <kugelfang@gentoo.org>
  10  Copyright (c) 2005, 2006 Andreas Jaggi <andreas.jaggi@waterwave.ch>
  11
  12  This program is free software; you can redistribute it and/or modify
  13  it under the terms of the GNU General Public License as published by
  14  the Free Software Foundation; either version 2 of the License, or
  15  (at your option) any later version.
  16
  17  This program is distributed in the hope that it will be useful,
  18  but WITHOUT ANY WARRANTY; without even the implied warranty of
  19  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  20  GNU General Public License for more details.
  21
  22  You should have received a copy of the GNU General Public License
  23  along with this program; see the file COPYING.  If not, write to
  24  the Free Software Foundation, Inc., 51 Franklin Steet, Fifth Floor,
  25  Boston, MA 02110-1301, USA.
  26
  27*/
  28
  29#include "phy_common.h"
  30#include "phy_g.h"
  31#include "phy_a.h"
  32#include "phy_n.h"
  33#include "phy_lp.h"
  34#include "phy_ht.h"
  35#include "phy_lcn.h"
  36#include "phy_ac.h"
  37#include "b43.h"
  38#include "main.h"
  39
  40
  41int b43_phy_allocate(struct b43_wldev *dev)
  42{
  43        struct b43_phy *phy = &(dev->phy);
  44        int err;
  45
  46        phy->ops = NULL;
  47
  48        switch (phy->type) {
  49        case B43_PHYTYPE_G:
  50#ifdef CONFIG_B43_PHY_G
  51                phy->ops = &b43_phyops_g;
  52#endif
  53                break;
  54        case B43_PHYTYPE_N:
  55#ifdef CONFIG_B43_PHY_N
  56                phy->ops = &b43_phyops_n;
  57#endif
  58                break;
  59        case B43_PHYTYPE_LP:
  60#ifdef CONFIG_B43_PHY_LP
  61                phy->ops = &b43_phyops_lp;
  62#endif
  63                break;
  64        case B43_PHYTYPE_HT:
  65#ifdef CONFIG_B43_PHY_HT
  66                phy->ops = &b43_phyops_ht;
  67#endif
  68                break;
  69        case B43_PHYTYPE_LCN:
  70#ifdef CONFIG_B43_PHY_LCN
  71                phy->ops = &b43_phyops_lcn;
  72#endif
  73                break;
  74        case B43_PHYTYPE_AC:
  75#ifdef CONFIG_B43_PHY_AC
  76                phy->ops = &b43_phyops_ac;
  77#endif
  78                break;
  79        }
  80        if (B43_WARN_ON(!phy->ops))
  81                return -ENODEV;
  82
  83        err = phy->ops->allocate(dev);
  84        if (err)
  85                phy->ops = NULL;
  86
  87        return err;
  88}
  89
  90void b43_phy_free(struct b43_wldev *dev)
  91{
  92        dev->phy.ops->free(dev);
  93        dev->phy.ops = NULL;
  94}
  95
  96int b43_phy_init(struct b43_wldev *dev)
  97{
  98        struct b43_phy *phy = &dev->phy;
  99        const struct b43_phy_operations *ops = phy->ops;
 100        int err;
 101
 102        /* During PHY init we need to use some channel. On the first init this
 103         * function is called *before* b43_op_config, so our pointer is NULL.
 104         */
 105        if (!phy->chandef) {
 106                phy->chandef = &dev->wl->hw->conf.chandef;
 107                phy->channel = phy->chandef->chan->hw_value;
 108        }
 109
 110        phy->ops->switch_analog(dev, true);
 111        b43_software_rfkill(dev, false);
 112
 113        err = ops->init(dev);
 114        if (err) {
 115                b43err(dev->wl, "PHY init failed\n");
 116                goto err_block_rf;
 117        }
 118        phy->do_full_init = false;
 119
 120        err = b43_switch_channel(dev, phy->channel);
 121        if (err) {
 122                b43err(dev->wl, "PHY init: Channel switch to default failed\n");
 123                goto err_phy_exit;
 124        }
 125
 126        return 0;
 127
 128err_phy_exit:
 129        phy->do_full_init = true;
 130        if (ops->exit)
 131                ops->exit(dev);
 132err_block_rf:
 133        b43_software_rfkill(dev, true);
 134
 135        return err;
 136}
 137
 138void b43_phy_exit(struct b43_wldev *dev)
 139{
 140        const struct b43_phy_operations *ops = dev->phy.ops;
 141
 142        b43_software_rfkill(dev, true);
 143        dev->phy.do_full_init = true;
 144        if (ops->exit)
 145                ops->exit(dev);
 146}
 147
 148bool b43_has_hardware_pctl(struct b43_wldev *dev)
 149{
 150        if (!dev->phy.hardware_power_control)
 151                return false;
 152        if (!dev->phy.ops->supports_hwpctl)
 153                return false;
 154        return dev->phy.ops->supports_hwpctl(dev);
 155}
 156
 157void b43_radio_lock(struct b43_wldev *dev)
 158{
 159        u32 macctl;
 160
 161#if B43_DEBUG
 162        B43_WARN_ON(dev->phy.radio_locked);
 163        dev->phy.radio_locked = true;
 164#endif
 165
 166        macctl = b43_read32(dev, B43_MMIO_MACCTL);
 167        macctl |= B43_MACCTL_RADIOLOCK;
 168        b43_write32(dev, B43_MMIO_MACCTL, macctl);
 169        /* Commit the write and wait for the firmware
 170         * to finish any radio register access. */
 171        b43_read32(dev, B43_MMIO_MACCTL);
 172        udelay(10);
 173}
 174
 175void b43_radio_unlock(struct b43_wldev *dev)
 176{
 177        u32 macctl;
 178
 179#if B43_DEBUG
 180        B43_WARN_ON(!dev->phy.radio_locked);
 181        dev->phy.radio_locked = false;
 182#endif
 183
 184        /* Commit any write */
 185        b43_read16(dev, B43_MMIO_PHY_VER);
 186        /* unlock */
 187        macctl = b43_read32(dev, B43_MMIO_MACCTL);
 188        macctl &= ~B43_MACCTL_RADIOLOCK;
 189        b43_write32(dev, B43_MMIO_MACCTL, macctl);
 190}
 191
 192void b43_phy_lock(struct b43_wldev *dev)
 193{
 194#if B43_DEBUG
 195        B43_WARN_ON(dev->phy.phy_locked);
 196        dev->phy.phy_locked = true;
 197#endif
 198        B43_WARN_ON(dev->dev->core_rev < 3);
 199
 200        if (!b43_is_mode(dev->wl, NL80211_IFTYPE_AP))
 201                b43_power_saving_ctl_bits(dev, B43_PS_AWAKE);
 202}
 203
 204void b43_phy_unlock(struct b43_wldev *dev)
 205{
 206#if B43_DEBUG
 207        B43_WARN_ON(!dev->phy.phy_locked);
 208        dev->phy.phy_locked = false;
 209#endif
 210        B43_WARN_ON(dev->dev->core_rev < 3);
 211
 212        if (!b43_is_mode(dev->wl, NL80211_IFTYPE_AP))
 213                b43_power_saving_ctl_bits(dev, 0);
 214}
 215
 216static inline void assert_mac_suspended(struct b43_wldev *dev)
 217{
 218        if (!B43_DEBUG)
 219                return;
 220        if ((b43_status(dev) >= B43_STAT_INITIALIZED) &&
 221            (dev->mac_suspended <= 0)) {
 222                b43dbg(dev->wl, "PHY/RADIO register access with "
 223                       "enabled MAC.\n");
 224                dump_stack();
 225        }
 226}
 227
 228u16 b43_radio_read(struct b43_wldev *dev, u16 reg)
 229{
 230        assert_mac_suspended(dev);
 231        dev->phy.writes_counter = 0;
 232        return dev->phy.ops->radio_read(dev, reg);
 233}
 234
 235void b43_radio_write(struct b43_wldev *dev, u16 reg, u16 value)
 236{
 237        assert_mac_suspended(dev);
 238        if (b43_bus_host_is_pci(dev->dev) &&
 239            ++dev->phy.writes_counter > B43_MAX_WRITES_IN_ROW) {
 240                b43_read32(dev, B43_MMIO_MACCTL);
 241                dev->phy.writes_counter = 1;
 242        }
 243        dev->phy.ops->radio_write(dev, reg, value);
 244}
 245
 246void b43_radio_mask(struct b43_wldev *dev, u16 offset, u16 mask)
 247{
 248        b43_radio_write16(dev, offset,
 249                          b43_radio_read16(dev, offset) & mask);
 250}
 251
 252void b43_radio_set(struct b43_wldev *dev, u16 offset, u16 set)
 253{
 254        b43_radio_write16(dev, offset,
 255                          b43_radio_read16(dev, offset) | set);
 256}
 257
 258void b43_radio_maskset(struct b43_wldev *dev, u16 offset, u16 mask, u16 set)
 259{
 260        b43_radio_write16(dev, offset,
 261                          (b43_radio_read16(dev, offset) & mask) | set);
 262}
 263
 264bool b43_radio_wait_value(struct b43_wldev *dev, u16 offset, u16 mask,
 265                          u16 value, int delay, int timeout)
 266{
 267        u16 val;
 268        int i;
 269
 270        for (i = 0; i < timeout; i += delay) {
 271                val = b43_radio_read(dev, offset);
 272                if ((val & mask) == value)
 273                        return true;
 274                udelay(delay);
 275        }
 276        return false;
 277}
 278
 279u16 b43_phy_read(struct b43_wldev *dev, u16 reg)
 280{
 281        assert_mac_suspended(dev);
 282        dev->phy.writes_counter = 0;
 283
 284        if (dev->phy.ops->phy_read)
 285                return dev->phy.ops->phy_read(dev, reg);
 286
 287        b43_write16f(dev, B43_MMIO_PHY_CONTROL, reg);
 288        return b43_read16(dev, B43_MMIO_PHY_DATA);
 289}
 290
 291void b43_phy_write(struct b43_wldev *dev, u16 reg, u16 value)
 292{
 293        assert_mac_suspended(dev);
 294        if (b43_bus_host_is_pci(dev->dev) &&
 295            ++dev->phy.writes_counter > B43_MAX_WRITES_IN_ROW) {
 296                b43_read16(dev, B43_MMIO_PHY_VER);
 297                dev->phy.writes_counter = 1;
 298        }
 299
 300        if (dev->phy.ops->phy_write)
 301                return dev->phy.ops->phy_write(dev, reg, value);
 302
 303        b43_write16f(dev, B43_MMIO_PHY_CONTROL, reg);
 304        b43_write16(dev, B43_MMIO_PHY_DATA, value);
 305}
 306
 307void b43_phy_copy(struct b43_wldev *dev, u16 destreg, u16 srcreg)
 308{
 309        b43_phy_write(dev, destreg, b43_phy_read(dev, srcreg));
 310}
 311
 312void b43_phy_mask(struct b43_wldev *dev, u16 offset, u16 mask)
 313{
 314        if (dev->phy.ops->phy_maskset) {
 315                assert_mac_suspended(dev);
 316                dev->phy.ops->phy_maskset(dev, offset, mask, 0);
 317        } else {
 318                b43_phy_write(dev, offset,
 319                              b43_phy_read(dev, offset) & mask);
 320        }
 321}
 322
 323void b43_phy_set(struct b43_wldev *dev, u16 offset, u16 set)
 324{
 325        if (dev->phy.ops->phy_maskset) {
 326                assert_mac_suspended(dev);
 327                dev->phy.ops->phy_maskset(dev, offset, 0xFFFF, set);
 328        } else {
 329                b43_phy_write(dev, offset,
 330                              b43_phy_read(dev, offset) | set);
 331        }
 332}
 333
 334void b43_phy_maskset(struct b43_wldev *dev, u16 offset, u16 mask, u16 set)
 335{
 336        if (dev->phy.ops->phy_maskset) {
 337                assert_mac_suspended(dev);
 338                dev->phy.ops->phy_maskset(dev, offset, mask, set);
 339        } else {
 340                b43_phy_write(dev, offset,
 341                              (b43_phy_read(dev, offset) & mask) | set);
 342        }
 343}
 344
 345void b43_phy_put_into_reset(struct b43_wldev *dev)
 346{
 347        u32 tmp;
 348
 349        switch (dev->dev->bus_type) {
 350#ifdef CONFIG_B43_BCMA
 351        case B43_BUS_BCMA:
 352                tmp = bcma_aread32(dev->dev->bdev, BCMA_IOCTL);
 353                tmp &= ~B43_BCMA_IOCTL_GMODE;
 354                tmp |= B43_BCMA_IOCTL_PHY_RESET;
 355                tmp |= BCMA_IOCTL_FGC;
 356                bcma_awrite32(dev->dev->bdev, BCMA_IOCTL, tmp);
 357                udelay(1);
 358
 359                tmp = bcma_aread32(dev->dev->bdev, BCMA_IOCTL);
 360                tmp &= ~BCMA_IOCTL_FGC;
 361                bcma_awrite32(dev->dev->bdev, BCMA_IOCTL, tmp);
 362                udelay(1);
 363                break;
 364#endif
 365#ifdef CONFIG_B43_SSB
 366        case B43_BUS_SSB:
 367                tmp = ssb_read32(dev->dev->sdev, SSB_TMSLOW);
 368                tmp &= ~B43_TMSLOW_GMODE;
 369                tmp |= B43_TMSLOW_PHYRESET;
 370                tmp |= SSB_TMSLOW_FGC;
 371                ssb_write32(dev->dev->sdev, SSB_TMSLOW, tmp);
 372                usleep_range(1000, 2000);
 373
 374                tmp = ssb_read32(dev->dev->sdev, SSB_TMSLOW);
 375                tmp &= ~SSB_TMSLOW_FGC;
 376                ssb_write32(dev->dev->sdev, SSB_TMSLOW, tmp);
 377                usleep_range(1000, 2000);
 378
 379                break;
 380#endif
 381        }
 382}
 383
 384void b43_phy_take_out_of_reset(struct b43_wldev *dev)
 385{
 386        u32 tmp;
 387
 388        switch (dev->dev->bus_type) {
 389#ifdef CONFIG_B43_BCMA
 390        case B43_BUS_BCMA:
 391                /* Unset reset bit (with forcing clock) */
 392                tmp = bcma_aread32(dev->dev->bdev, BCMA_IOCTL);
 393                tmp &= ~B43_BCMA_IOCTL_PHY_RESET;
 394                tmp &= ~B43_BCMA_IOCTL_PHY_CLKEN;
 395                tmp |= BCMA_IOCTL_FGC;
 396                bcma_awrite32(dev->dev->bdev, BCMA_IOCTL, tmp);
 397                udelay(1);
 398
 399                /* Do not force clock anymore */
 400                tmp = bcma_aread32(dev->dev->bdev, BCMA_IOCTL);
 401                tmp &= ~BCMA_IOCTL_FGC;
 402                tmp |= B43_BCMA_IOCTL_PHY_CLKEN;
 403                bcma_awrite32(dev->dev->bdev, BCMA_IOCTL, tmp);
 404                udelay(1);
 405                break;
 406#endif
 407#ifdef CONFIG_B43_SSB
 408        case B43_BUS_SSB:
 409                /* Unset reset bit (with forcing clock) */
 410                tmp = ssb_read32(dev->dev->sdev, SSB_TMSLOW);
 411                tmp &= ~B43_TMSLOW_PHYRESET;
 412                tmp &= ~B43_TMSLOW_PHYCLKEN;
 413                tmp |= SSB_TMSLOW_FGC;
 414                ssb_write32(dev->dev->sdev, SSB_TMSLOW, tmp);
 415                ssb_read32(dev->dev->sdev, SSB_TMSLOW); /* flush */
 416                usleep_range(1000, 2000);
 417
 418                tmp = ssb_read32(dev->dev->sdev, SSB_TMSLOW);
 419                tmp &= ~SSB_TMSLOW_FGC;
 420                tmp |= B43_TMSLOW_PHYCLKEN;
 421                ssb_write32(dev->dev->sdev, SSB_TMSLOW, tmp);
 422                ssb_read32(dev->dev->sdev, SSB_TMSLOW); /* flush */
 423                usleep_range(1000, 2000);
 424                break;
 425#endif
 426        }
 427}
 428
 429int b43_switch_channel(struct b43_wldev *dev, unsigned int new_channel)
 430{
 431        struct b43_phy *phy = &(dev->phy);
 432        u16 channelcookie, savedcookie;
 433        int err;
 434
 435        /* First we set the channel radio code to prevent the
 436         * firmware from sending ghost packets.
 437         */
 438        channelcookie = new_channel;
 439        if (b43_current_band(dev->wl) == NL80211_BAND_5GHZ)
 440                channelcookie |= B43_SHM_SH_CHAN_5GHZ;
 441        /* FIXME: set 40Mhz flag if required */
 442        if (0)
 443                channelcookie |= B43_SHM_SH_CHAN_40MHZ;
 444        savedcookie = b43_shm_read16(dev, B43_SHM_SHARED, B43_SHM_SH_CHAN);
 445        b43_shm_write16(dev, B43_SHM_SHARED, B43_SHM_SH_CHAN, channelcookie);
 446
 447        /* Now try to switch the PHY hardware channel. */
 448        err = phy->ops->switch_channel(dev, new_channel);
 449        if (err)
 450                goto err_restore_cookie;
 451
 452        /* Wait for the radio to tune to the channel and stabilize. */
 453        msleep(8);
 454
 455        return 0;
 456
 457err_restore_cookie:
 458        b43_shm_write16(dev, B43_SHM_SHARED,
 459                        B43_SHM_SH_CHAN, savedcookie);
 460
 461        return err;
 462}
 463
 464void b43_software_rfkill(struct b43_wldev *dev, bool blocked)
 465{
 466        struct b43_phy *phy = &dev->phy;
 467
 468        b43_mac_suspend(dev);
 469        phy->ops->software_rfkill(dev, blocked);
 470        phy->radio_on = !blocked;
 471        b43_mac_enable(dev);
 472}
 473
 474/**
 475 * b43_phy_txpower_adjust_work - TX power workqueue.
 476 *
 477 * Workqueue for updating the TX power parameters in hardware.
 478 */
 479void b43_phy_txpower_adjust_work(struct work_struct *work)
 480{
 481        struct b43_wl *wl = container_of(work, struct b43_wl,
 482                                         txpower_adjust_work);
 483        struct b43_wldev *dev;
 484
 485        mutex_lock(&wl->mutex);
 486        dev = wl->current_dev;
 487
 488        if (likely(dev && (b43_status(dev) >= B43_STAT_STARTED)))
 489                dev->phy.ops->adjust_txpower(dev);
 490
 491        mutex_unlock(&wl->mutex);
 492}
 493
 494void b43_phy_txpower_check(struct b43_wldev *dev, unsigned int flags)
 495{
 496        struct b43_phy *phy = &dev->phy;
 497        unsigned long now = jiffies;
 498        enum b43_txpwr_result result;
 499
 500        if (!(flags & B43_TXPWR_IGNORE_TIME)) {
 501                /* Check if it's time for a TXpower check. */
 502                if (time_before(now, phy->next_txpwr_check_time))
 503                        return; /* Not yet */
 504        }
 505        /* The next check will be needed in two seconds, or later. */
 506        phy->next_txpwr_check_time = round_jiffies(now + (HZ * 2));
 507
 508        if ((dev->dev->board_vendor == SSB_BOARDVENDOR_BCM) &&
 509            (dev->dev->board_type == SSB_BOARD_BU4306))
 510                return; /* No software txpower adjustment needed */
 511
 512        result = phy->ops->recalc_txpower(dev, !!(flags & B43_TXPWR_IGNORE_TSSI));
 513        if (result == B43_TXPWR_RES_DONE)
 514                return; /* We are done. */
 515        B43_WARN_ON(result != B43_TXPWR_RES_NEED_ADJUST);
 516        B43_WARN_ON(phy->ops->adjust_txpower == NULL);
 517
 518        /* We must adjust the transmission power in hardware.
 519         * Schedule b43_phy_txpower_adjust_work(). */
 520        ieee80211_queue_work(dev->wl->hw, &dev->wl->txpower_adjust_work);
 521}
 522
 523int b43_phy_shm_tssi_read(struct b43_wldev *dev, u16 shm_offset)
 524{
 525        const bool is_ofdm = (shm_offset != B43_SHM_SH_TSSI_CCK);
 526        unsigned int a, b, c, d;
 527        unsigned int average;
 528        u32 tmp;
 529
 530        tmp = b43_shm_read32(dev, B43_SHM_SHARED, shm_offset);
 531        a = tmp & 0xFF;
 532        b = (tmp >> 8) & 0xFF;
 533        c = (tmp >> 16) & 0xFF;
 534        d = (tmp >> 24) & 0xFF;
 535        if (a == 0 || a == B43_TSSI_MAX ||
 536            b == 0 || b == B43_TSSI_MAX ||
 537            c == 0 || c == B43_TSSI_MAX ||
 538            d == 0 || d == B43_TSSI_MAX)
 539                return -ENOENT;
 540        /* The values are OK. Clear them. */
 541        tmp = B43_TSSI_MAX | (B43_TSSI_MAX << 8) |
 542              (B43_TSSI_MAX << 16) | (B43_TSSI_MAX << 24);
 543        b43_shm_write32(dev, B43_SHM_SHARED, shm_offset, tmp);
 544
 545        if (is_ofdm) {
 546                a = (a + 32) & 0x3F;
 547                b = (b + 32) & 0x3F;
 548                c = (c + 32) & 0x3F;
 549                d = (d + 32) & 0x3F;
 550        }
 551
 552        /* Get the average of the values with 0.5 added to each value. */
 553        average = (a + b + c + d + 2) / 4;
 554        if (is_ofdm) {
 555                /* Adjust for CCK-boost */
 556                if (b43_shm_read16(dev, B43_SHM_SHARED, B43_SHM_SH_HOSTF1)
 557                    & B43_HF_CCKBOOST)
 558                        average = (average >= 13) ? (average - 13) : 0;
 559        }
 560
 561        return average;
 562}
 563
 564void b43_phyop_switch_analog_generic(struct b43_wldev *dev, bool on)
 565{
 566        b43_write16(dev, B43_MMIO_PHY0, on ? 0 : 0xF4);
 567}
 568
 569
 570bool b43_is_40mhz(struct b43_wldev *dev)
 571{
 572        return dev->phy.chandef->width == NL80211_CHAN_WIDTH_40;
 573}
 574
 575/* http://bcm-v4.sipsolutions.net/802.11/PHY/N/BmacPhyClkFgc */
 576void b43_phy_force_clock(struct b43_wldev *dev, bool force)
 577{
 578        u32 tmp;
 579
 580        WARN_ON(dev->phy.type != B43_PHYTYPE_N &&
 581                dev->phy.type != B43_PHYTYPE_HT &&
 582                dev->phy.type != B43_PHYTYPE_AC);
 583
 584        switch (dev->dev->bus_type) {
 585#ifdef CONFIG_B43_BCMA
 586        case B43_BUS_BCMA:
 587                tmp = bcma_aread32(dev->dev->bdev, BCMA_IOCTL);
 588                if (force)
 589                        tmp |= BCMA_IOCTL_FGC;
 590                else
 591                        tmp &= ~BCMA_IOCTL_FGC;
 592                bcma_awrite32(dev->dev->bdev, BCMA_IOCTL, tmp);
 593                break;
 594#endif
 595#ifdef CONFIG_B43_SSB
 596        case B43_BUS_SSB:
 597                tmp = ssb_read32(dev->dev->sdev, SSB_TMSLOW);
 598                if (force)
 599                        tmp |= SSB_TMSLOW_FGC;
 600                else
 601                        tmp &= ~SSB_TMSLOW_FGC;
 602                ssb_write32(dev->dev->sdev, SSB_TMSLOW, tmp);
 603                break;
 604#endif
 605        }
 606}
 607
 608/* http://bcm-v4.sipsolutions.net/802.11/PHY/Cordic */
 609struct b43_c32 b43_cordic(int theta)
 610{
 611        static const u32 arctg[] = {
 612                2949120, 1740967, 919879, 466945, 234379, 117304,
 613                  58666,   29335,  14668,   7334,   3667,   1833,
 614                    917,     458,    229,    115,     57,     29,
 615        };
 616        u8 i;
 617        s32 tmp;
 618        s8 signx = 1;
 619        u32 angle = 0;
 620        struct b43_c32 ret = { .i = 39797, .q = 0, };
 621
 622        while (theta > (180 << 16))
 623                theta -= (360 << 16);
 624        while (theta < -(180 << 16))
 625                theta += (360 << 16);
 626
 627        if (theta > (90 << 16)) {
 628                theta -= (180 << 16);
 629                signx = -1;
 630        } else if (theta < -(90 << 16)) {
 631                theta += (180 << 16);
 632                signx = -1;
 633        }
 634
 635        for (i = 0; i <= 17; i++) {
 636                if (theta > angle) {
 637                        tmp = ret.i - (ret.q >> i);
 638                        ret.q += ret.i >> i;
 639                        ret.i = tmp;
 640                        angle += arctg[i];
 641                } else {
 642                        tmp = ret.i + (ret.q >> i);
 643                        ret.q -= ret.i >> i;
 644                        ret.i = tmp;
 645                        angle -= arctg[i];
 646                }
 647        }
 648
 649        ret.i *= signx;
 650        ret.q *= signx;
 651
 652        return ret;
 653}
 654