summaryrefslogtreecommitdiff
path: root/Kernel/Devices/PATAChannel.cpp
blob: 7d649ddf2b970a5ad4d64ca772d20f4fd4d1c969 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
/*
 * Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 * 1. Redistributions of source code must retain the above copyright notice, this
 *    list of conditions and the following disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above copyright notice,
 *    this list of conditions and the following disclaimer in the documentation
 *    and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
 * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
 * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#include <AK/ByteBuffer.h>
#include <AK/StringView.h>
#include <Kernel/Devices/PATAChannel.h>
#include <Kernel/Devices/PATADiskDevice.h>
#include <Kernel/FileSystem/ProcFS.h>
#include <Kernel/Process.h>
#include <Kernel/VM/MemoryManager.h>
#include <LibBareMetal/IO.h>

namespace Kernel {

#define PATA_PRIMARY_IRQ 14
#define PATA_SECONDARY_IRQ 15

//#define PATA_DEBUG

#define ATA_SR_BSY 0x80
#define ATA_SR_DRDY 0x40
#define ATA_SR_DF 0x20
#define ATA_SR_DSC 0x10
#define ATA_SR_DRQ 0x08
#define ATA_SR_CORR 0x04
#define ATA_SR_IDX 0x02
#define ATA_SR_ERR 0x01

#define ATA_ER_BBK 0x80
#define ATA_ER_UNC 0x40
#define ATA_ER_MC 0x20
#define ATA_ER_IDNF 0x10
#define ATA_ER_MCR 0x08
#define ATA_ER_ABRT 0x04
#define ATA_ER_TK0NF 0x02
#define ATA_ER_AMNF 0x01

#define ATA_CMD_READ_PIO 0x20
#define ATA_CMD_READ_PIO_EXT 0x24
#define ATA_CMD_READ_DMA 0xC8
#define ATA_CMD_READ_DMA_EXT 0x25
#define ATA_CMD_WRITE_PIO 0x30
#define ATA_CMD_WRITE_PIO_EXT 0x34
#define ATA_CMD_WRITE_DMA 0xCA
#define ATA_CMD_WRITE_DMA_EXT 0x35
#define ATA_CMD_CACHE_FLUSH 0xE7
#define ATA_CMD_CACHE_FLUSH_EXT 0xEA
#define ATA_CMD_PACKET 0xA0
#define ATA_CMD_IDENTIFY_PACKET 0xA1
#define ATA_CMD_IDENTIFY 0xEC

#define ATAPI_CMD_READ 0xA8
#define ATAPI_CMD_EJECT 0x1B

#define ATA_IDENT_DEVICETYPE 0
#define ATA_IDENT_CYLINDERS 2
#define ATA_IDENT_HEADS 6
#define ATA_IDENT_SECTORS 12
#define ATA_IDENT_SERIAL 20
#define ATA_IDENT_MODEL 54
#define ATA_IDENT_CAPABILITIES 98
#define ATA_IDENT_FIELDVALID 106
#define ATA_IDENT_MAX_LBA 120
#define ATA_IDENT_COMMANDSETS 164
#define ATA_IDENT_MAX_LBA_EXT 200

#define IDE_ATA 0x00
#define IDE_ATAPI 0x01

#define ATA_REG_DATA 0x00
#define ATA_REG_ERROR 0x01
#define ATA_REG_FEATURES 0x01
#define ATA_REG_SECCOUNT0 0x02
#define ATA_REG_LBA0 0x03
#define ATA_REG_LBA1 0x04
#define ATA_REG_LBA2 0x05
#define ATA_REG_HDDEVSEL 0x06
#define ATA_REG_COMMAND 0x07
#define ATA_REG_STATUS 0x07
#define ATA_CTL_CONTROL 0x00
#define ATA_CTL_ALTSTATUS 0x00
#define ATA_CTL_DEVADDRESS 0x01

#define PCI_Mass_Storage_Class 0x1
#define PCI_IDE_Controller_Subclass 0x1
static Lock& s_lock()
{
    static Lock* lock;
    if (!lock)
        lock = new Lock;

    return *lock;
};

OwnPtr<PATAChannel> PATAChannel::create(ChannelType type, bool force_pio)
{
    PCI::Address pci_address;
    PCI::enumerate_all([&](const PCI::Address& address, PCI::ID id) {
        if (PCI::get_class(address) == PCI_Mass_Storage_Class && PCI::get_subclass(address) == PCI_IDE_Controller_Subclass) {
            pci_address = address;
            klog() << "PATAChannel: PATA Controller found! id=" << String::format("%w", id.vendor_id) << ":" << String::format("%w", id.device_id);
        }
    });
    return make<PATAChannel>(pci_address, type, force_pio);
}

PATAChannel::PATAChannel(PCI::Address address, ChannelType type, bool force_pio)
    : PCI::Device(address, (type == ChannelType::Primary ? PATA_PRIMARY_IRQ : PATA_SECONDARY_IRQ))
    , m_channel_number((type == ChannelType::Primary ? 0 : 1))
    , m_io_base((type == ChannelType::Primary ? 0x1F0 : 0x170))
    , m_control_base((type == ChannelType::Primary ? 0x3f6 : 0x376))
    , m_bus_master_base(PCI::get_BAR4(pci_address()) & 0xfffc)
{
    disable_irq();

    m_dma_enabled.resource() = true;
    ProcFS::add_sys_bool("ide_dma", m_dma_enabled);

    m_prdt_page = MM.allocate_supervisor_physical_page();
    initialize(force_pio);
    detect_disks();
    disable_irq();
}

PATAChannel::~PATAChannel()
{
}

void PATAChannel::prepare_for_irq()
{
    cli();
    enable_irq();
}

void PATAChannel::initialize(bool force_pio)
{

    if (force_pio) {
        klog() << "PATAChannel: Requested to force PIO mode; not setting up DMA";
        return;
    }
    // Let's try to set up DMA transfers.
    PCI::enable_bus_mastering(pci_address());
    PCI::enable_interrupt_line(pci_address());
    prdt().end_of_table = 0x8000;
    m_dma_buffer_page = MM.allocate_supervisor_physical_page();
    klog() << "PATAChannel: Bus master IDE: " << m_bus_master_base;
}

static void print_ide_status(u8 status)
{
    klog() << "PATAChannel: print_ide_status: DRQ=" << ((status & ATA_SR_DRQ) != 0) << " BSY=" << ((status & ATA_SR_BSY) != 0) << " DRDY=" << ((status & ATA_SR_DRDY) != 0) << " DSC=" << ((status & ATA_SR_DSC) != 0) << " DF=" << ((status & ATA_SR_DF) != 0) << " CORR=" << ((status & ATA_SR_CORR) != 0) << " IDX=" << ((status & ATA_SR_IDX) != 0) << " ERR=" << ((status & ATA_SR_ERR) != 0);
}

void PATAChannel::wait_for_irq()
{
    Thread::current->wait_on(m_irq_queue);
    disable_irq();
}

void PATAChannel::handle_irq(const RegisterState&)
{
    u8 status = m_io_base.offset(ATA_REG_STATUS).in<u8>();
    if (status & ATA_SR_ERR) {
        print_ide_status(status);
        m_device_error = m_io_base.offset(ATA_REG_ERROR).in<u8>();
        klog() << "PATAChannel: Error " << String::format("%b", m_device_error) << "!";
    } else {
        m_device_error = 0;
    }
#ifdef PATA_DEBUG
    klog() << "PATAChannel: interrupt: DRQ=" << ((status & ATA_SR_DRQ) != 0) << " BSY=" << ((status & ATA_SR_BSY) != 0) << " DRDY=" << ((status & ATA_SR_DRDY) != 0);
#endif
    m_irq_queue.wake_all();
}

static void io_delay()
{
    for (int i = 0; i < 4; ++i)
        IO::in8(0x3f6);
}

void PATAChannel::detect_disks()
{
    // There are only two possible disks connected to a channel
    for (auto i = 0; i < 2; i++) {
        m_io_base.offset(ATA_REG_HDDEVSEL).out<u8>(0xA0 | (i << 4)); // First, we need to select the drive itself

        // Apparently these need to be 0 before sending IDENTIFY?!
        m_io_base.offset(ATA_REG_SECCOUNT0).out<u8>(0x00);
        m_io_base.offset(ATA_REG_LBA0).out<u8>(0x00);
        m_io_base.offset(ATA_REG_LBA1).out<u8>(0x00);
        m_io_base.offset(ATA_REG_LBA2).out<u8>(0x00);

        m_io_base.offset(ATA_REG_COMMAND).out<u8>(ATA_CMD_IDENTIFY); // Send the ATA_IDENTIFY command

        // Wait for the BSY flag to be reset
        while (m_io_base.offset(ATA_REG_STATUS).in<u8>() & ATA_SR_BSY)
            ;

        if (m_io_base.offset(ATA_REG_STATUS).in<u8>() == 0x00) {
#ifdef PATA_DEBUG
            klog() << "PATAChannel: No " << (i == 0 ? "master" : "slave") << " disk detected!";
#endif
            continue;
        }

        ByteBuffer wbuf = ByteBuffer::create_uninitialized(512);
        ByteBuffer bbuf = ByteBuffer::create_uninitialized(512);
        u8* b = bbuf.data();
        u16* w = (u16*)wbuf.data();
        const u16* wbufbase = (u16*)wbuf.data();

        for (u32 i = 0; i < 256; ++i) {
            u16 data = m_io_base.offset(ATA_REG_DATA).in<u16>();
            *(w++) = data;
            *(b++) = MSB(data);
            *(b++) = LSB(data);
        }

        // "Unpad" the device name string.
        for (u32 i = 93; i > 54 && bbuf[i] == ' '; --i)
            bbuf[i] = 0;

        u8 cyls = wbufbase[1];
        u8 heads = wbufbase[3];
        u8 spt = wbufbase[6];

        klog() << "PATAChannel: Name=" << ((char*)bbuf.data() + 54) << ", C/H/Spt=" << cyls << "/" << heads << "/" << spt;

        int major = (m_channel_number == 0) ? 3 : 4;
        if (i == 0) {
            m_master = PATADiskDevice::create(*this, PATADiskDevice::DriveType::Master, major, 0);
            m_master->set_drive_geometry(cyls, heads, spt);
        } else {
            m_slave = PATADiskDevice::create(*this, PATADiskDevice::DriveType::Slave, major, 1);
            m_slave->set_drive_geometry(cyls, heads, spt);
        }
    }
}

bool PATAChannel::ata_read_sectors_with_dma(u32 lba, u16 count, u8* outbuf, bool slave_request)
{
    LOCKER(s_lock());
#ifdef PATA_DEBUG
    dbg() << "PATAChannel::ata_read_sectors_with_dma (" << lba << " x" << count << ") -> " << outbuf;
#endif

    prdt().offset = m_dma_buffer_page->paddr();
    prdt().size = 512 * count;

    ASSERT(prdt().size <= PAGE_SIZE);

    // Stop bus master
    m_bus_master_base.out<u8>(0);

    // Write the PRDT location
    m_bus_master_base.offset(4).out(m_prdt_page->paddr().get());

    // Turn on "Interrupt" and "Error" flag. The error flag should be cleared by hardware.
    m_bus_master_base.offset(2).out<u8>(m_bus_master_base.offset(2).in<u8>() | 0x6);

    // Set transfer direction
    m_bus_master_base.out<u8>(0x8);

    while (m_io_base.offset(ATA_REG_STATUS).in<u8>() & ATA_SR_BSY)
        ;

    u8 devsel = 0xe0;
    if (slave_request)
        devsel |= 0x10;

    m_control_base.offset(ATA_CTL_CONTROL).out<u8>(0);
    m_io_base.offset(ATA_REG_HDDEVSEL).out<u8>(devsel | (static_cast<u8>(slave_request) << 4));
    io_delay();

    m_io_base.offset(ATA_REG_FEATURES).out<u8>(0);

    m_io_base.offset(ATA_REG_SECCOUNT0).out<u8>(0);
    m_io_base.offset(ATA_REG_LBA0).out<u8>(0);
    m_io_base.offset(ATA_REG_LBA1).out<u8>(0);
    m_io_base.offset(ATA_REG_LBA2).out<u8>(0);

    m_io_base.offset(ATA_REG_SECCOUNT0).out<u8>(count);
    m_io_base.offset(ATA_REG_LBA0).out<u8>((lba & 0x000000ff) >> 0);
    m_io_base.offset(ATA_REG_LBA1).out<u8>((lba & 0x0000ff00) >> 8);
    m_io_base.offset(ATA_REG_LBA2).out<u8>((lba & 0x00ff0000) >> 16);

    for (;;) {
        auto status = m_io_base.offset(ATA_REG_STATUS).in<u8>();
        if (!(status & ATA_SR_BSY) && (status & ATA_SR_DRDY))
            break;
    }

    m_io_base.offset(ATA_REG_COMMAND).out<u8>(ATA_CMD_READ_DMA_EXT);
    io_delay();

    prepare_for_irq();
    // Start bus master
    m_bus_master_base.out<u8>(0x9);

    wait_for_irq();

    if (m_device_error)
        return false;

    memcpy(outbuf, m_dma_buffer_page->paddr().offset(0xc0000000).as_ptr(), 512 * count);

    // I read somewhere that this may trigger a cache flush so let's do it.
    m_bus_master_base.offset(2).out<u8>(m_bus_master_base.offset(2).in<u8>() | 0x6);
    return true;
}

bool PATAChannel::ata_write_sectors_with_dma(u32 lba, u16 count, const u8* inbuf, bool slave_request)
{
    LOCKER(s_lock());
#ifdef PATA_DEBUG
    dbg() << "PATAChannel::ata_write_sectors_with_dma (" << lba << " x" << count << ") <- " << inbuf;
#endif

    prdt().offset = m_dma_buffer_page->paddr();
    prdt().size = 512 * count;

    memcpy(m_dma_buffer_page->paddr().offset(0xc0000000).as_ptr(), inbuf, 512 * count);

    ASSERT(prdt().size <= PAGE_SIZE);

    // Stop bus master
    m_bus_master_base.out<u8>(0);

    // Write the PRDT location
    m_bus_master_base.offset(4).out<u32>(m_prdt_page->paddr().get());

    // Turn on "Interrupt" and "Error" flag. The error flag should be cleared by hardware.
    m_bus_master_base.offset(2).out<u8>(m_bus_master_base.offset(2).in<u8>() | 0x6);

    while (m_io_base.offset(ATA_REG_STATUS).in<u8>() & ATA_SR_BSY)
        ;

    u8 devsel = 0xe0;
    if (slave_request)
        devsel |= 0x10;

    m_control_base.offset(ATA_CTL_CONTROL).out<u8>(0);
    m_io_base.offset(ATA_REG_HDDEVSEL).out<u8>(devsel | (static_cast<u8>(slave_request) << 4));
    io_delay();

    m_io_base.offset(ATA_REG_FEATURES).out<u8>(0);

    m_io_base.offset(ATA_REG_SECCOUNT0).out<u8>(0);
    m_io_base.offset(ATA_REG_LBA0).out<u8>(0);
    m_io_base.offset(ATA_REG_LBA1).out<u8>(0);
    m_io_base.offset(ATA_REG_LBA2).out<u8>(0);

    m_io_base.offset(ATA_REG_SECCOUNT0).out<u8>(count);
    m_io_base.offset(ATA_REG_LBA0).out<u8>((lba & 0x000000ff) >> 0);
    m_io_base.offset(ATA_REG_LBA1).out<u8>((lba & 0x0000ff00) >> 8);
    m_io_base.offset(ATA_REG_LBA2).out<u8>((lba & 0x00ff0000) >> 16);

    for (;;) {
        auto status = m_io_base.offset(ATA_REG_STATUS).in<u8>();
        if (!(status & ATA_SR_BSY) && (status & ATA_SR_DRDY))
            break;
    }

    m_io_base.offset(ATA_REG_COMMAND).out<u8>(ATA_CMD_WRITE_DMA_EXT);
    io_delay();

    prepare_for_irq();
    // Start bus master
    m_bus_master_base.out<u8>(0x1);
    wait_for_irq();

    if (m_device_error)
        return false;

    // I read somewhere that this may trigger a cache flush so let's do it.
    m_bus_master_base.offset(2).out<u8>(m_bus_master_base.offset(2).in<u8>() | 0x6);
    return true;
}

bool PATAChannel::ata_read_sectors(u32 start_sector, u16 count, u8* outbuf, bool slave_request)
{
    ASSERT(count <= 256);
    LOCKER(s_lock());
#ifdef PATA_DEBUG
    dbg() << "PATAChannel::ata_read_sectors request (" << count << " sector(s) @ " << start_sector << " into " << outbuf << ")";
#endif

    while (m_io_base.offset(ATA_REG_STATUS).in<u8>() & ATA_SR_BSY)
        ;

#ifdef PATA_DEBUG
    klog() << "PATAChannel: Reading " << count << " sector(s) @ LBA " << start_sector;
#endif

    u8 devsel = 0xe0;
    if (slave_request)
        devsel |= 0x10;

    m_io_base.offset(ATA_REG_SECCOUNT0).out<u8>(count == 256 ? 0 : LSB(count));
    m_io_base.offset(ATA_REG_LBA0).out<u8>(start_sector & 0xff);
    m_io_base.offset(ATA_REG_LBA1).out<u8>((start_sector >> 8) & 0xff);
    m_io_base.offset(ATA_REG_LBA2).out<u8>((start_sector >> 16) & 0xff);
    m_io_base.offset(ATA_REG_HDDEVSEL).out<u8>(devsel | ((start_sector >> 24) & 0xf));

    IO::out8(0x3F6, 0x08);
    while (!(m_io_base.offset(ATA_REG_STATUS).in<u8>() & ATA_SR_DRDY))
        ;

    prepare_for_irq();
    m_io_base.offset(ATA_REG_COMMAND).out<u8>(ATA_CMD_READ_PIO);
    wait_for_irq();

    if (m_device_error)
        return false;

    for (int i = 0; i < count; i++) {
        io_delay();

        while (m_io_base.offset(ATA_REG_STATUS).in<u8>() & ATA_SR_BSY)
            ;

        u8 status = m_io_base.offset(ATA_REG_STATUS).in<u8>();
        ASSERT(status & ATA_SR_DRQ);
#ifdef PATA_DEBUG
        dbg() << "PATAChannel: Retrieving 512 bytes (part " << i << ") (status=" << String::format("%b", status) << "), outbuf=(" << (outbuf + (512 * i)) << ")...";
#endif

        IO::repeated_in16(m_io_base.offset(ATA_REG_DATA).get(), outbuf + (512 * i), 256);
    }

    return true;
}

bool PATAChannel::ata_write_sectors(u32 start_sector, u16 count, const u8* inbuf, bool slave_request)
{
    ASSERT(count <= 256);
    LOCKER(s_lock());
#ifdef PATA_DEBUG
    klog() << "PATAChannel::ata_write_sectors request (" << count << " sector(s) @ " << start_sector << ")";
#endif

    while (m_io_base.offset(ATA_REG_STATUS).in<u8>() & ATA_SR_BSY)
        ;

#ifdef PATA_DEBUG
    klog() << "PATAChannel: Writing " << count << " sector(s) @ LBA " << start_sector;
#endif

    u8 devsel = 0xe0;
    if (slave_request)
        devsel |= 0x10;

    m_io_base.offset(ATA_REG_SECCOUNT0).out<u8>(count == 256 ? 0 : LSB(count));
    m_io_base.offset(ATA_REG_LBA0).out<u8>(start_sector & 0xff);
    m_io_base.offset(ATA_REG_LBA1).out<u8>((start_sector >> 8) & 0xff);
    m_io_base.offset(ATA_REG_LBA2).out<u8>((start_sector >> 16) & 0xff);
    m_io_base.offset(ATA_REG_HDDEVSEL).out<u8>(devsel | ((start_sector >> 24) & 0xf));

    IO::out8(0x3F6, 0x08);
    while (!(m_io_base.offset(ATA_REG_STATUS).in<u8>() & ATA_SR_DRDY))
        ;

    m_io_base.offset(ATA_REG_COMMAND).out<u8>(ATA_CMD_WRITE_PIO);

    for (int i = 0; i < count; i++) {
        io_delay();
        while (m_io_base.offset(ATA_REG_STATUS).in<u8>() & ATA_SR_BSY)
            ;

        u8 status = m_io_base.offset(ATA_REG_STATUS).in<u8>();
        ASSERT(status & ATA_SR_DRQ);

#ifdef PATA_DEBUG
        dbg() << "PATAChannel: Writing 512 bytes (part " << i << ") (status=" << String::format("%b", status) << "), inbuf=(" << (inbuf + (512 * i)) << ")...";
#endif

        IO::repeated_out16(m_io_base.offset(ATA_REG_DATA).get(), inbuf + (512 * i), 256);
        prepare_for_irq();
        wait_for_irq();
        status = m_io_base.offset(ATA_REG_STATUS).in<u8>();
        ASSERT(!(status & ATA_SR_BSY));
    }
    prepare_for_irq();
    m_io_base.offset(ATA_REG_COMMAND).out<u8>(ATA_CMD_CACHE_FLUSH);
    wait_for_irq();
    u8 status = m_io_base.offset(ATA_REG_STATUS).in<u8>();
    ASSERT(!(status & ATA_SR_BSY));

    return !m_device_error;
}

}