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-rw-r--r--src/devices/disk.c571
1 files changed, 571 insertions, 0 deletions
diff --git a/src/devices/disk.c b/src/devices/disk.c
new file mode 100644
index 0000000..14fc631
--- /dev/null
+++ b/src/devices/disk.c
@@ -0,0 +1,571 @@
+#include "devices/disk.h"
+#include <ctype.h>
+#include <debug.h>
+#include <stdbool.h>
+#include <stdio.h>
+#include "devices/timer.h"
+#include "threads/io.h"
+#include "threads/interrupt.h"
+#include "threads/synch.h"
+
+/* The code in this file is an interface to an ATA (IDE)
+ controller. It attempts to comply to [ATA-3]. */
+
+/* ATA command block port addresses. */
+#define reg_data(CHANNEL) ((CHANNEL)->reg_base + 0) /* Data. */
+#define reg_error(CHANNEL) ((CHANNEL)->reg_base + 1) /* Error. */
+#define reg_nsect(CHANNEL) ((CHANNEL)->reg_base + 2) /* Sector Count. */
+#define reg_lbal(CHANNEL) ((CHANNEL)->reg_base + 3) /* LBA 0:7. */
+#define reg_lbam(CHANNEL) ((CHANNEL)->reg_base + 4) /* LBA 15:8. */
+#define reg_lbah(CHANNEL) ((CHANNEL)->reg_base + 5) /* LBA 23:16. */
+#define reg_device(CHANNEL) ((CHANNEL)->reg_base + 6) /* Device/LBA 27:24. */
+#define reg_status(CHANNEL) ((CHANNEL)->reg_base + 7) /* Status (r/o). */
+#define reg_command(CHANNEL) reg_status (CHANNEL) /* Command (w/o). */
+
+/* ATA control block port addresses.
+ (If we supported non-legacy ATA controllers this would not be
+ flexible enough, but it's fine for what we do.) */
+#define reg_ctl(CHANNEL) ((CHANNEL)->reg_base + 0x206) /* Control (w/o). */
+#define reg_alt_status(CHANNEL) reg_ctl (CHANNEL) /* Alt Status (r/o). */
+
+/* Alternate Status Register bits. */
+#define STA_BSY 0x80 /* Busy. */
+#define STA_DRDY 0x40 /* Device Ready. */
+#define STA_DRQ 0x08 /* Data Request. */
+
+/* Control Register bits. */
+#define CTL_SRST 0x04 /* Software Reset. */
+
+/* Device Register bits. */
+#define DEV_MBS 0xa0 /* Must be set. */
+#define DEV_LBA 0x40 /* Linear based addressing. */
+#define DEV_DEV 0x10 /* Select device: 0=master, 1=slave. */
+
+/* Commands.
+ Many more are defined but this is the small subset that we
+ use. */
+#define CMD_IDENTIFY_DEVICE 0xec /* IDENTIFY DEVICE. */
+#define CMD_READ_SECTOR_RETRY 0x20 /* READ SECTOR with retries. */
+#define CMD_WRITE_SECTOR_RETRY 0x30 /* WRITE SECTOR with retries. */
+
+/* An ATA device. */
+struct disk
+ {
+ char name[8]; /* Name, e.g. "hd0:1". */
+ struct channel *channel; /* Channel disk is on. */
+ int dev_no; /* Device 0 or 1 for master or slave. */
+
+ bool is_ata; /* 1=This device is an ATA disk. */
+ disk_sector_t capacity; /* Capacity in sectors (if is_ata). */
+
+ long long read_cnt; /* Number of sectors read. */
+ long long write_cnt; /* Number of sectors written. */
+ };
+
+/* An ATA channel (aka controller).
+ Each channel can control up to two disks. */
+struct channel
+ {
+ char name[8]; /* Name, e.g. "hd0". */
+ uint16_t reg_base; /* Base I/O port. */
+ uint8_t irq; /* Interrupt in use. */
+
+ struct lock lock; /* Must acquire to access the controller. */
+ bool expecting_interrupt; /* True if an interrupt is expected, false if
+ any interrupt would be spurious. */
+ struct semaphore completion_wait; /* Up'd by interrupt handler. */
+
+ struct disk devices[2]; /* The devices on this channel. */
+ };
+
+/* We support the two "legacy" ATA channels found in a standard PC. */
+#define CHANNEL_CNT 2
+static struct channel channels[CHANNEL_CNT];
+
+static void reset_channel (struct channel *);
+static bool check_device_type (struct disk *);
+static void identify_ata_device (struct disk *);
+
+static void select_sector (struct disk *, disk_sector_t);
+static void issue_pio_command (struct channel *, uint8_t command);
+static void input_sector (struct channel *, void *);
+static void output_sector (struct channel *, const void *);
+
+static void wait_until_idle (const struct disk *);
+static bool wait_while_busy (const struct disk *);
+static void select_device (const struct disk *);
+static void select_device_wait (const struct disk *);
+
+static void interrupt_handler (struct intr_frame *);
+
+/* Initialize the disk subsystem and detect disks. */
+void
+disk_init (void)
+{
+ size_t chan_no;
+
+ for (chan_no = 0; chan_no < CHANNEL_CNT; chan_no++)
+ {
+ struct channel *c = &channels[chan_no];
+ int dev_no;
+
+ /* Initialize channel. */
+ snprintf (c->name, sizeof c->name, "hd%zu", chan_no);
+ switch (chan_no)
+ {
+ case 0:
+ c->reg_base = 0x1f0;
+ c->irq = 14 + 0x20;
+ break;
+ case 1:
+ c->reg_base = 0x170;
+ c->irq = 15 + 0x20;
+ break;
+ default:
+ NOT_REACHED ();
+ }
+ lock_init (&c->lock);
+ c->expecting_interrupt = false;
+ sema_init (&c->completion_wait, 0);
+
+ /* Initialize devices. */
+ for (dev_no = 0; dev_no < 2; dev_no++)
+ {
+ struct disk *d = &c->devices[dev_no];
+ snprintf (d->name, sizeof d->name, "%s:%d", c->name, dev_no);
+ d->channel = c;
+ d->dev_no = dev_no;
+
+ d->is_ata = false;
+ d->capacity = 0;
+
+ d->read_cnt = d->write_cnt = 0;
+ }
+
+ /* Register interrupt handler. */
+ intr_register_ext (c->irq, interrupt_handler, c->name);
+
+ /* Reset hardware. */
+ reset_channel (c);
+
+ /* Distinguish ATA hard disks from other devices. */
+ if (check_device_type (&c->devices[0]))
+ check_device_type (&c->devices[1]);
+
+ /* Read hard disk identity information. */
+ for (dev_no = 0; dev_no < 2; dev_no++)
+ if (c->devices[dev_no].is_ata)
+ identify_ata_device (&c->devices[dev_no]);
+ }
+}
+
+/* Prints disk statistics. */
+void
+disk_print_stats (void)
+{
+ int chan_no;
+
+ for (chan_no = 0; chan_no < CHANNEL_CNT; chan_no++)
+ {
+ int dev_no;
+
+ for (dev_no = 0; dev_no < 2; dev_no++)
+ {
+ struct disk *d = disk_get (chan_no, dev_no);
+ if (d != NULL && d->is_ata)
+ printf ("%s: %lld reads, %lld writes\n",
+ d->name, d->read_cnt, d->write_cnt);
+ }
+ }
+}
+
+/* Returns the disk numbered DEV_NO--either 0 or 1 for master or
+ slave, respectively--within the channel numbered CHAN_NO.
+
+ Pintos uses disks this way:
+ 0:0 - boot loader, command line args, and operating system kernel
+ 0:1 - file system
+ 1:0 - scratch
+ 1:1 - swap
+*/
+struct disk *
+disk_get (int chan_no, int dev_no)
+{
+ ASSERT (dev_no == 0 || dev_no == 1);
+
+ if (chan_no < (int) CHANNEL_CNT)
+ {
+ struct disk *d = &channels[chan_no].devices[dev_no];
+ if (d->is_ata)
+ return d;
+ }
+ return NULL;
+}
+
+/* Returns the size of disk D, measured in DISK_SECTOR_SIZE-byte
+ sectors. */
+disk_sector_t
+disk_size (struct disk *d)
+{
+ ASSERT (d != NULL);
+
+ return d->capacity;
+}
+
+/* Reads sector SEC_NO from disk D into BUFFER, which must have
+ room for DISK_SECTOR_SIZE bytes.
+ Internally synchronizes accesses to disks, so external
+ per-disk locking is unneeded. */
+void
+disk_read (struct disk *d, disk_sector_t sec_no, void *buffer)
+{
+ struct channel *c;
+
+ ASSERT (d != NULL);
+ ASSERT (buffer != NULL);
+
+ c = d->channel;
+ lock_acquire (&c->lock);
+ select_sector (d, sec_no);
+ issue_pio_command (c, CMD_READ_SECTOR_RETRY);
+ sema_down (&c->completion_wait);
+ if (!wait_while_busy (d))
+ PANIC ("%s: disk read failed, sector=%"PRDSNu, d->name, sec_no);
+ input_sector (c, buffer);
+ d->read_cnt++;
+ lock_release (&c->lock);
+}
+
+/* Write sector SEC_NO to disk D from BUFFER, which must contain
+ DISK_SECTOR_SIZE bytes. Returns after the disk has
+ acknowledged receiving the data.
+ Internally synchronizes accesses to disks, so external
+ per-disk locking is unneeded. */
+void
+disk_write (struct disk *d, disk_sector_t sec_no, const void *buffer)
+{
+ struct channel *c;
+
+ ASSERT (d != NULL);
+ ASSERT (buffer != NULL);
+
+ c = d->channel;
+ lock_acquire (&c->lock);
+ select_sector (d, sec_no);
+ issue_pio_command (c, CMD_WRITE_SECTOR_RETRY);
+ if (!wait_while_busy (d))
+ PANIC ("%s: disk write failed, sector=%"PRDSNu, d->name, sec_no);
+ output_sector (c, buffer);
+ sema_down (&c->completion_wait);
+ d->write_cnt++;
+ lock_release (&c->lock);
+}
+
+/* Disk detection and identification. */
+
+static void print_ata_string (char *string, size_t size);
+
+/* Resets an ATA channel and waits for any devices present on it
+ to finish the reset. */
+static void
+reset_channel (struct channel *c)
+{
+ bool present[2];
+ int dev_no;
+
+ /* The ATA reset sequence depends on which devices are present,
+ so we start by detecting device presence. */
+ for (dev_no = 0; dev_no < 2; dev_no++)
+ {
+ struct disk *d = &c->devices[dev_no];
+
+ select_device (d);
+
+ outb (reg_nsect (c), 0x55);
+ outb (reg_lbal (c), 0xaa);
+
+ outb (reg_nsect (c), 0xaa);
+ outb (reg_lbal (c), 0x55);
+
+ outb (reg_nsect (c), 0x55);
+ outb (reg_lbal (c), 0xaa);
+
+ present[dev_no] = (inb (reg_nsect (c)) == 0x55
+ && inb (reg_lbal (c)) == 0xaa);
+ }
+
+ /* Issue soft reset sequence, which selects device 0 as a side effect.
+ Also enable interrupts. */
+ outb (reg_ctl (c), 0);
+ timer_usleep (10);
+ outb (reg_ctl (c), CTL_SRST);
+ timer_usleep (10);
+ outb (reg_ctl (c), 0);
+
+ timer_msleep (150);
+
+ /* Wait for device 0 to clear BSY. */
+ if (present[0])
+ {
+ select_device (&c->devices[0]);
+ wait_while_busy (&c->devices[0]);
+ }
+
+ /* Wait for device 1 to clear BSY. */
+ if (present[1])
+ {
+ int i;
+
+ select_device (&c->devices[1]);
+ for (i = 0; i < 3000; i++)
+ {
+ if (inb (reg_nsect (c)) == 1 && inb (reg_lbal (c)) == 1)
+ break;
+ timer_msleep (10);
+ }
+ wait_while_busy (&c->devices[1]);
+ }
+}
+
+/* Checks whether device D is an ATA disk and sets D's is_ata
+ member appropriately. If D is device 0 (master), returns true
+ if it's possible that a slave (device 1) exists on this
+ channel. If D is device 1 (slave), the return value is not
+ meaningful. */
+static bool
+check_device_type (struct disk *d)
+{
+ struct channel *c = d->channel;
+ uint8_t error, lbam, lbah, status;
+
+ select_device (d);
+
+ error = inb (reg_error (c));
+ lbam = inb (reg_lbam (c));
+ lbah = inb (reg_lbah (c));
+ status = inb (reg_status (c));
+
+ if ((error != 1 && (error != 0x81 || d->dev_no == 1))
+ || (status & STA_DRDY) == 0
+ || (status & STA_BSY) != 0)
+ {
+ d->is_ata = false;
+ return error != 0x81;
+ }
+ else
+ {
+ d->is_ata = (lbam == 0 && lbah == 0) || (lbam == 0x3c && lbah == 0xc3);
+ return true;
+ }
+}
+
+/* Sends an IDENTIFY DEVICE command to disk D and reads the
+ response. Initializes D's capacity member based on the result
+ and prints a message describing the disk to the console. */
+static void
+identify_ata_device (struct disk *d)
+{
+ struct channel *c = d->channel;
+ uint16_t id[DISK_SECTOR_SIZE / 2];
+
+ ASSERT (d->is_ata);
+
+ /* Send the IDENTIFY DEVICE command, wait for an interrupt
+ indicating the device's response is ready, and read the data
+ into our buffer. */
+ select_device_wait (d);
+ issue_pio_command (c, CMD_IDENTIFY_DEVICE);
+ sema_down (&c->completion_wait);
+ if (!wait_while_busy (d))
+ {
+ d->is_ata = false;
+ return;
+ }
+ input_sector (c, id);
+
+ /* Calculate capacity. */
+ d->capacity = id[60] | ((uint32_t) id[61] << 16);
+
+ /* Print identification message. */
+ printf ("%s: detected %'"PRDSNu" sector (", d->name, d->capacity);
+ if (d->capacity > 1024 / DISK_SECTOR_SIZE * 1024 * 1024)
+ printf ("%"PRDSNu" GB",
+ d->capacity / (1024 / DISK_SECTOR_SIZE * 1024 * 1024));
+ else if (d->capacity > 1024 / DISK_SECTOR_SIZE * 1024)
+ printf ("%"PRDSNu" MB", d->capacity / (1024 / DISK_SECTOR_SIZE * 1024));
+ else if (d->capacity > 1024 / DISK_SECTOR_SIZE)
+ printf ("%"PRDSNu" kB", d->capacity / (1024 / DISK_SECTOR_SIZE));
+ else
+ printf ("%"PRDSNu" byte", d->capacity * DISK_SECTOR_SIZE);
+ printf (") disk, model \"");
+ print_ata_string ((char *) &id[27], 40);
+ printf ("\", serial \"");
+ print_ata_string ((char *) &id[10], 20);
+ printf ("\"\n");
+}
+
+/* Prints STRING, which consists of SIZE bytes in a funky format:
+ each pair of bytes is in reverse order. Does not print
+ trailing whitespace and/or nulls. */
+static void
+print_ata_string (char *string, size_t size)
+{
+ size_t i;
+
+ /* Find the last non-white, non-null character. */
+ for (; size > 0; size--)
+ {
+ int c = string[(size - 1) ^ 1];
+ if (c != '\0' && !isspace (c))
+ break;
+ }
+
+ /* Print. */
+ for (i = 0; i < size; i++)
+ printf ("%c", string[i ^ 1]);
+}
+
+/* Selects device D, waiting for it to become ready, and then
+ writes SEC_NO to the disk's sector selection registers. (We
+ use LBA mode.) */
+static void
+select_sector (struct disk *d, disk_sector_t sec_no)
+{
+ struct channel *c = d->channel;
+
+ ASSERT (sec_no < d->capacity);
+ ASSERT (sec_no < (1UL << 28));
+
+ select_device_wait (d);
+ outb (reg_nsect (c), 1);
+ outb (reg_lbal (c), sec_no);
+ outb (reg_lbam (c), sec_no >> 8);
+ outb (reg_lbah (c), (sec_no >> 16));
+ outb (reg_device (c),
+ DEV_MBS | DEV_LBA | (d->dev_no == 1 ? DEV_DEV : 0) | (sec_no >> 24));
+}
+
+/* Writes COMMAND to channel C and prepares for receiving a
+ completion interrupt. */
+static void
+issue_pio_command (struct channel *c, uint8_t command)
+{
+ /* Interrupts must be enabled or our semaphore will never be
+ up'd by the completion handler. */
+ ASSERT (intr_get_level () == INTR_ON);
+
+ c->expecting_interrupt = true;
+ outb (reg_command (c), command);
+}
+
+/* Reads a sector from channel C's data register in PIO mode into
+ SECTOR, which must have room for DISK_SECTOR_SIZE bytes. */
+static void
+input_sector (struct channel *c, void *sector)
+{
+ insw (reg_data (c), sector, DISK_SECTOR_SIZE / 2);
+}
+
+/* Writes SECTOR to channel C's data register in PIO mode.
+ SECTOR must contain DISK_SECTOR_SIZE bytes. */
+static void
+output_sector (struct channel *c, const void *sector)
+{
+ outsw (reg_data (c), sector, DISK_SECTOR_SIZE / 2);
+}
+
+/* Low-level ATA primitives. */
+
+/* Wait up to 10 seconds for the controller to become idle, that
+ is, for the BSY and DRQ bits to clear in the status register.
+
+ As a side effect, reading the status register clears any
+ pending interrupt. */
+static void
+wait_until_idle (const struct disk *d)
+{
+ int i;
+
+ for (i = 0; i < 1000; i++)
+ {
+ if ((inb (reg_status (d->channel)) & (STA_BSY | STA_DRQ)) == 0)
+ return;
+ timer_usleep (10);
+ }
+
+ printf ("%s: idle timeout\n", d->name);
+}
+
+/* Wait up to 30 seconds for disk D to clear BSY,
+ and then return the status of the DRQ bit.
+ The ATA standards say that a disk may take as long as that to
+ complete its reset. */
+static bool
+wait_while_busy (const struct disk *d)
+{
+ struct channel *c = d->channel;
+ int i;
+
+ for (i = 0; i < 3000; i++)
+ {
+ if (i == 700)
+ printf ("%s: busy, waiting...", d->name);
+ if (!(inb (reg_alt_status (c)) & STA_BSY))
+ {
+ if (i >= 700)
+ printf ("ok\n");
+ return (inb (reg_alt_status (c)) & STA_DRQ) != 0;
+ }
+ timer_msleep (10);
+ }
+
+ printf ("failed\n");
+ return false;
+}
+
+/* Program D's channel so that D is now the selected disk. */
+static void
+select_device (const struct disk *d)
+{
+ struct channel *c = d->channel;
+ uint8_t dev = DEV_MBS;
+ if (d->dev_no == 1)
+ dev |= DEV_DEV;
+ outb (reg_device (c), dev);
+ inb (reg_alt_status (c));
+ timer_nsleep (400);
+}
+
+/* Select disk D in its channel, as select_device(), but wait for
+ the channel to become idle before and after. */
+static void
+select_device_wait (const struct disk *d)
+{
+ wait_until_idle (d);
+ select_device (d);
+ wait_until_idle (d);
+}
+
+/* ATA interrupt handler. */
+static void
+interrupt_handler (struct intr_frame *f)
+{
+ struct channel *c;
+
+ for (c = channels; c < channels + CHANNEL_CNT; c++)
+ if (f->vec_no == c->irq)
+ {
+ if (c->expecting_interrupt)
+ {
+ inb (reg_status (c)); /* Acknowledge interrupt. */
+ sema_up (&c->completion_wait); /* Wake up waiter. */
+ }
+ else
+ printf ("%s: unexpected interrupt\n", c->name);
+ return;
+ }
+
+ NOT_REACHED ();
+}
+
+
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