1 #include "devices/disk.h"
6 #include "devices/timer.h"
7 #include "threads/io.h"
8 #include "threads/interrupt.h"
9 #include "threads/synch.h"
11 /* The code in this file is an interface to an ATA (IDE)
12 controller. It attempts to comply to [ATA-3]. */
14 /* ATA command block port addresses. */
15 #define reg_data(CHANNEL) ((CHANNEL)->reg_base + 0) /* Data. */
16 #define reg_error(CHANNEL) ((CHANNEL)->reg_base + 1) /* Error. */
17 #define reg_nsect(CHANNEL) ((CHANNEL)->reg_base + 2) /* Sector Count. */
18 #define reg_lbal(CHANNEL) ((CHANNEL)->reg_base + 3) /* LBA 0:7. */
19 #define reg_lbam(CHANNEL) ((CHANNEL)->reg_base + 4) /* LBA 15:8. */
20 #define reg_lbah(CHANNEL) ((CHANNEL)->reg_base + 5) /* LBA 23:16. */
21 #define reg_device(CHANNEL) ((CHANNEL)->reg_base + 6) /* Device/LBA 27:24. */
22 #define reg_status(CHANNEL) ((CHANNEL)->reg_base + 7) /* Status (r/o). */
23 #define reg_command(CHANNEL) reg_status (CHANNEL) /* Command (w/o). */
25 /* ATA control block port addresses.
26 (If we supported non-legacy ATA controllers this would not be
27 flexible enough, but it's fine for what we do.) */
28 #define reg_ctl(CHANNEL) ((CHANNEL)->reg_base + 0x206) /* Control (w/o). */
29 #define reg_alt_status(CHANNEL) reg_ctl (CHANNEL) /* Alt Status (r/o). */
31 /* Alternate Status Register bits. */
32 #define STA_BSY 0x80 /* Busy. */
33 #define STA_DRQ 0x08 /* Data Request. */
35 /* Control Register bits. */
36 #define CTL_SRST 0x04 /* Software Reset. */
38 /* Device Register bits. */
39 #define DEV_MBS 0xa0 /* Must be set. */
40 #define DEV_LBA 0x40 /* Linear based addressing. */
41 #define DEV_DEV 0x10 /* Select device: 0=master, 1=slave. */
44 Many more are defined but this is the small subset that we
46 #define CMD_IDENTIFY_DEVICE 0xec /* IDENTIFY DEVICE. */
47 #define CMD_READ_SECTOR_RETRY 0x20 /* READ SECTOR with retries. */
48 #define CMD_WRITE_SECTOR_RETRY 0x30 /* WRITE SECTOR with retries. */
53 char name[8]; /* Name, e.g. "hd0:1". */
54 struct channel *channel; /* Channel disk is on. */
55 int dev_no; /* Device 0 or 1 for master or slave. */
57 bool is_ata; /* 1=This device is an ATA disk. */
58 disk_sector_t capacity; /* Capacity in sectors (if is_ata). */
60 long long read_cnt; /* Number of sectors read. */
61 long long write_cnt; /* Number of sectors written. */
64 /* An ATA channel (aka controller).
65 Each channel can control up to two disks. */
68 char name[8]; /* Name, e.g. "hd0". */
69 uint16_t reg_base; /* Base I/O port. */
70 uint8_t irq; /* Interrupt in use. */
72 struct lock lock; /* Must acquire to access the controller. */
73 bool expecting_interrupt; /* True if an interrupt is expected, false if
74 any interrupt would be spurious. */
75 struct semaphore completion_wait; /* Up'd by interrupt handler. */
77 struct disk devices[2]; /* The devices on this channel. */
80 /* We support the two "legacy" ATA channels found in a standard PC. */
82 static struct channel channels[CHANNEL_CNT];
84 static void reset_channel (struct channel *);
85 static bool check_device_type (struct disk *);
86 static void identify_ata_device (struct disk *);
88 static void select_sector (struct disk *, disk_sector_t);
89 static void issue_pio_command (struct channel *, uint8_t command);
90 static void input_sector (struct channel *, void *);
91 static void output_sector (struct channel *, const void *);
93 static void wait_until_idle (const struct disk *);
94 static bool wait_while_busy (const struct disk *);
95 static void select_device (const struct disk *);
96 static void select_device_wait (const struct disk *);
98 static void interrupt_handler (struct intr_frame *);
100 /* Initialize the disk subsystem and detect disks. */
106 for (chan_no = 0; chan_no < CHANNEL_CNT; chan_no++)
108 struct channel *c = &channels[chan_no];
111 /* Initialize channel. */
112 snprintf (c->name, sizeof c->name, "hd%zu", chan_no);
126 lock_init (&c->lock, c->name);
127 c->expecting_interrupt = false;
128 sema_init (&c->completion_wait, 0, c->name);
130 /* Initialize devices. */
131 for (dev_no = 0; dev_no < 2; dev_no++)
133 struct disk *d = &c->devices[dev_no];
134 snprintf (d->name, sizeof d->name, "%s:%d", c->name, dev_no);
141 d->read_cnt = d->write_cnt = 0;
144 /* Register interrupt handler. */
145 intr_register (c->irq, 0, INTR_OFF, interrupt_handler, c->name);
147 /* Reset hardware. */
150 /* Distinguish ATA hard disks from other devices. */
151 if (check_device_type (&c->devices[0]))
152 check_device_type (&c->devices[1]);
154 /* Read hard disk identity information. */
155 for (dev_no = 0; dev_no < 2; dev_no++)
156 if (c->devices[dev_no].is_ata)
157 identify_ata_device (&c->devices[dev_no]);
161 /* Prints disk statistics. */
163 disk_print_stats (void)
167 for (chan_no = 0; chan_no < CHANNEL_CNT; chan_no++)
171 for (dev_no = 0; dev_no < 2; dev_no++)
173 struct disk *d = disk_get (chan_no, dev_no);
174 if (d != NULL && d->is_ata)
175 printf ("%s: %lld reads, %lld writes\n",
176 d->name, d->read_cnt, d->write_cnt);
181 /* Returns the disk numbered DEV_NO--either 0 or 1 for master or
182 slave, respectively--within the channel numbered CHAN_NO. */
184 disk_get (int chan_no, int dev_no)
186 ASSERT (dev_no == 0 || dev_no == 1);
188 if (chan_no < (int) CHANNEL_CNT)
190 struct disk *d = &channels[chan_no].devices[dev_no];
197 /* Returns the size of disk D, measured in DISK_SECTOR_SIZE-byte
200 disk_size (struct disk *d)
207 /* Reads sector SEC_NO from disk D into BUFFER, which must have
208 room for DISK_SECTOR_SIZE bytes. */
210 disk_read (struct disk *d, disk_sector_t sec_no, void *buffer)
215 ASSERT (buffer != NULL);
218 lock_acquire (&c->lock);
219 select_sector (d, sec_no);
220 issue_pio_command (c, CMD_READ_SECTOR_RETRY);
221 sema_down (&c->completion_wait);
222 if (!wait_while_busy (d))
223 PANIC ("%s: disk read failed, sector=%"PRDSNu, d->name, sec_no);
224 input_sector (c, buffer);
226 lock_release (&c->lock);
229 /* Write sector SEC_NO to disk D from BUFFER, which must contain
230 DISK_SECTOR_SIZE bytes. Returns after the disk has
231 acknowledged receiving the data. */
233 disk_write (struct disk *d, disk_sector_t sec_no, const void *buffer)
238 ASSERT (buffer != NULL);
241 lock_acquire (&c->lock);
242 select_sector (d, sec_no);
243 issue_pio_command (c, CMD_WRITE_SECTOR_RETRY);
244 if (!wait_while_busy (d))
245 PANIC ("%s: disk write failed, sector=%"PRDSNu, d->name, sec_no);
246 output_sector (c, buffer);
247 sema_down (&c->completion_wait);
249 lock_release (&c->lock);
252 /* Disk detection and identification. */
254 static void print_ata_string (char *string, size_t size);
256 /* Resets an ATA channel and waits for any devices present on it
257 to finish the reset. */
259 reset_channel (struct channel *c)
264 /* The ATA reset sequence depends on which devices are present,
265 so we start by detecting device presence. */
266 for (dev_no = 0; dev_no < 2; dev_no++)
268 struct disk *d = &c->devices[dev_no];
272 outb (reg_nsect (c), 0x55);
273 outb (reg_lbal (c), 0xaa);
275 outb (reg_nsect (c), 0xaa);
276 outb (reg_lbal (c), 0x55);
278 outb (reg_nsect (c), 0x55);
279 outb (reg_lbal (c), 0xaa);
281 present[dev_no] = (inb (reg_nsect (c)) == 0x55
282 && inb (reg_lbal (c)) == 0xaa);
285 /* Issue soft reset sequence, which selects device 0 as a side effect.
286 Also enable interrupts. */
287 outb (reg_ctl (c), 0);
289 outb (reg_ctl (c), CTL_SRST);
291 outb (reg_ctl (c), 0);
295 /* Wait for device 0 to clear BSY. */
298 select_device (&c->devices[0]);
299 wait_while_busy (&c->devices[0]);
302 /* Wait for device 1 to clear BSY. */
307 select_device (&c->devices[1]);
308 for (i = 0; i < 3000; i++)
310 if (inb (reg_nsect (c)) == 1 && inb (reg_lbal (c)) == 1)
314 wait_while_busy (&c->devices[1]);
318 /* Checks whether device D is an ATA disk and sets D's is_ata
319 member appropriately. If D is device 0 (master), returns true
320 if it's possible that a slave (device 1) exists on this
321 channel. If D is device 1 (slave), the return value is not
324 check_device_type (struct disk *d)
326 struct channel *c = d->channel;
327 uint8_t error, lbam, lbah;
331 error = inb (reg_error (c));
332 lbam = inb (reg_lbam (c));
333 lbah = inb (reg_lbah (c));
335 if (error != 1 && (error != 0x81 || d->dev_no == 1))
338 return error != 0x81;
342 d->is_ata = (lbam == 0 && lbah == 0) || (lbam == 0x3c && lbah == 0xc3);
347 /* Sends an IDENTIFY DEVICE command to disk D and reads the
348 response. Initializes D's capacity member based on the result
349 and prints a message describing the disk to the console. */
351 identify_ata_device (struct disk *d)
353 struct channel *c = d->channel;
354 uint16_t id[DISK_SECTOR_SIZE / 2];
358 /* Send the IDENTIFY DEVICE command, wait for an interrupt
359 indicating the device's response is ready, and read the data
361 select_device_wait (d);
362 issue_pio_command (c, CMD_IDENTIFY_DEVICE);
363 sema_down (&c->completion_wait);
364 if (!wait_while_busy (d))
369 input_sector (c, id);
371 /* Calculate capacity. */
372 d->capacity = id[60] | ((uint32_t) id[61] << 16);
374 /* Print identification message. */
375 printf ("%s: detected %'"PRDSNu" sector (", d->name, d->capacity);
376 if (d->capacity > 1024 / DISK_SECTOR_SIZE * 1024 * 1024)
377 printf ("%"PRDSNu" GB",
378 d->capacity / (1024 / DISK_SECTOR_SIZE * 1024 * 1024));
379 else if (d->capacity > 1024 / DISK_SECTOR_SIZE * 1024)
380 printf ("%"PRDSNu" MB", d->capacity / (1024 / DISK_SECTOR_SIZE * 1024));
381 else if (d->capacity > 1024 / DISK_SECTOR_SIZE)
382 printf ("%"PRDSNu" kB", d->capacity / (1024 / DISK_SECTOR_SIZE));
384 printf ("%"PRDSNu" byte", d->capacity * DISK_SECTOR_SIZE);
385 printf (") disk, model \"");
386 print_ata_string ((char *) &id[27], 40);
387 printf ("\", serial \"");
388 print_ata_string ((char *) &id[10], 20);
392 /* Prints STRING, which consists of SIZE bytes in a funky format:
393 each pair of bytes is in reverse order. Does not print
394 trailing whitespace and/or nulls. */
396 print_ata_string (char *string, size_t size)
400 /* Find the last non-white, non-null character. */
401 for (; size > 0; size--)
403 int c = string[(size - 1) ^ 1];
404 if (c != '\0' && !isspace (c))
409 for (i = 0; i < size; i++)
410 printf ("%c", string[i ^ 1]);
413 /* Selects device D, waiting for it to become ready, and then
414 writes SEC_NO to the disk's sector selection registers. (We
417 select_sector (struct disk *d, disk_sector_t sec_no)
419 struct channel *c = d->channel;
421 ASSERT (sec_no < d->capacity);
422 ASSERT (sec_no < (1UL << 28));
424 select_device_wait (d);
425 outb (reg_nsect (c), 1);
426 outb (reg_lbal (c), sec_no);
427 outb (reg_lbam (c), sec_no >> 8);
428 outb (reg_lbah (c), (sec_no >> 16));
429 outb (reg_device (c),
430 DEV_MBS | DEV_LBA | (d->dev_no == 1 ? DEV_DEV : 0) | (sec_no >> 24));
433 /* Writes COMMAND to channel C and prepares for receiving a
434 completion interrupt. */
436 issue_pio_command (struct channel *c, uint8_t command)
438 /* Interrupts must be enabled or our semaphore will never be
439 up'd by the completion handler. */
440 ASSERT (intr_get_level () == INTR_ON);
442 c->expecting_interrupt = true;
443 outb (reg_command (c), command);
446 /* Reads a sector from channel C's data register in PIO mode into
447 SECTOR, which must have room for DISK_SECTOR_SIZE bytes. */
449 input_sector (struct channel *c, void *sector)
451 insw (reg_data (c), sector, DISK_SECTOR_SIZE / 2);
454 /* Writes SECTOR to channel C's data register in PIO mode.
455 SECTOR must contain DISK_SECTOR_SIZE bytes. */
457 output_sector (struct channel *c, const void *sector)
459 outsw (reg_data (c), sector, DISK_SECTOR_SIZE / 2);
462 /* Low-level ATA primitives. */
464 /* Wait up to 10 seconds for the controller to become idle, that
465 is, for the BSY and DRQ bits to clear in the status register.
467 As a side effect, reading the status register clears any
468 pending interrupt. */
470 wait_until_idle (const struct disk *d)
474 for (i = 0; i < 1000; i++)
476 if ((inb (reg_status (d->channel)) & (STA_BSY | STA_DRQ)) == 0)
481 printf ("%s: idle timeout\n", d->name);
484 /* Wait up to 30 seconds for disk D to clear BSY,
485 and then return the status of the DRQ bit.
486 The ATA standards say that a disk may take as long as that to
487 complete its reset. */
489 wait_while_busy (const struct disk *d)
491 struct channel *c = d->channel;
494 for (i = 0; i < 3000; i++)
497 printf ("%s: busy, waiting...", d->name);
498 if (!(inb (reg_alt_status (c)) & STA_BSY))
502 return (inb (reg_alt_status (c)) & STA_DRQ) != 0;
511 /* Program D's channel so that D is now the selected disk. */
513 select_device (const struct disk *d)
515 struct channel *c = d->channel;
516 uint8_t dev = DEV_MBS;
519 outb (reg_device (c), dev);
520 inb (reg_alt_status (c));
524 /* Select disk D in its channel, as select_device(), but wait for
525 the channel to become idle before and after. */
527 select_device_wait (const struct disk *d)
534 /* ATA interrupt handler. */
536 interrupt_handler (struct intr_frame *f)
540 for (c = channels; c < channels + CHANNEL_CNT; c++)
541 if (f->vec_no == c->irq)
543 if (c->expecting_interrupt)
545 inb (reg_status (c)); /* Acknowledge interrupt. */
546 sema_up (&c->completion_wait); /* Wake up waiter. */
549 printf ("%s: unexpected interrupt\n", c->name);