1 files changed, 527 insertions, 0 deletions

diff --git a/devices/ide.c b/devices/ide.c
new file mode 100644
index 0000000..2cc0292
--- /dev/null
+++ b/devices/ide.c
@@ -0,0 +1,527 @@
+#include "devices/ide.h"
+#include <ctype.h>
+#include <debug.h>
+#include <stdbool.h>
+#include <stdio.h>
+#include "devices/block.h"
+#include "devices/partition.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 ata_disk
+  {
+    char name[8];               /* Name, e.g. "hda". */
+    struct channel *channel;    /* Channel that disk is attached to. */
+    int dev_no;                 /* Device 0 or 1 for master or slave. */
+    bool is_ata;                /* Is device an ATA disk? */
+  };
+
+/* An ATA channel (aka controller).
+   Each channel can control up to two disks. */
+struct channel
+  {
+    char name[8];               /* Name, e.g. "ide0". */
+    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 ata_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 struct block_operations ide_operations;
+
+static void reset_channel (struct channel *);
+static bool check_device_type (struct ata_disk *);
+static void identify_ata_device (struct ata_disk *);
+
+static void select_sector (struct ata_disk *, block_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 ata_disk *);
+static bool wait_while_busy (const struct ata_disk *);
+static void select_device (const struct ata_disk *);
+static void select_device_wait (const struct ata_disk *);
+
+static void interrupt_handler (struct intr_frame *);
+
+/* Initialize the disk subsystem and detect disks. */
+void
+ide_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, "ide%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 ata_disk *d = &c->devices[dev_no];
+          snprintf (d->name, sizeof d->name,
+                    "hd%c", 'a' + chan_no * 2 + dev_no); 
+          d->channel = c;
+          d->dev_no = dev_no;
+          d->is_ata = false;
+        }
+
+      /* 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]);
+    }
+}
+
+/* Disk detection and identification. */
+
+static char *descramble_ata_string (char *, int 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 ata_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 ata_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.  Registers the disk with the block device
+   layer. */
+static void
+identify_ata_device (struct ata_disk *d) 
+{
+  struct channel *c = d->channel;
+  char id[BLOCK_SECTOR_SIZE];
+  block_sector_t capacity;
+  char *model, *serial;
+  char extra_info[128];
+  struct block *block;
+
+  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.
+     Read model name and serial number. */
+  capacity = *(uint32_t *) &id[60 * 2];
+  model = descramble_ata_string (&id[10 * 2], 20);
+  serial = descramble_ata_string (&id[27 * 2], 40);
+  snprintf (extra_info, sizeof extra_info,
+            "model \"%s\", serial \"%s\"", model, serial);
+
+  /* Disable access to IDE disks over 1 GB, which are likely
+     physical IDE disks rather than virtual ones.  If we don't
+     allow access to those, we're less likely to scribble on
+     someone's important data.  You can disable this check by
+     hand if you really want to do so. */
+  if (capacity >= 1024 * 1024 * 1024 / BLOCK_SECTOR_SIZE)
+    {
+      printf ("%s: ignoring ", d->name);
+      print_human_readable_size (capacity * 512);
+      printf ("disk for safety\n");
+      d->is_ata = false;
+      return;
+    }
+
+  /* Register. */
+  block = block_register (d->name, BLOCK_RAW, extra_info, capacity,
+                          &ide_operations, d);
+  partition_scan (block);
+}
+
+/* Translates STRING, which consists of SIZE bytes in a funky
+   format, into a null-terminated string in-place.  Drops
+   trailing whitespace and null bytes.  Returns STRING.  */
+static char *
+descramble_ata_string (char *string, int size) 
+{
+  int i;
+
+  /* Swap all pairs of bytes. */
+  for (i = 0; i + 1 < size; i += 2)
+    {
+      char tmp = string[i];
+      string[i] = string[i + 1];
+      string[i + 1] = tmp;
+    }
+
+  /* Find the last non-white, non-null character. */
+  for (size--; size > 0; size--)
+    {
+      int c = string[size - 1];
+      if (c != '\0' && !isspace (c))
+        break; 
+    }
+  string[size] = '\0';
+
+  return string;
+}
+
+/* Reads sector SEC_NO from disk D into BUFFER, which must have
+   room for BLOCK_SECTOR_SIZE bytes.
+   Internally synchronizes accesses to disks, so external
+   per-disk locking is unneeded. */
+static void
+ide_read (void *d_, block_sector_t sec_no, void *buffer)
+{
+  struct ata_disk *d = d_;
+  struct channel *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);
+  lock_release (&c->lock);
+}
+
+/* Write sector SEC_NO to disk D from BUFFER, which must contain
+   BLOCK_SECTOR_SIZE bytes.  Returns after the disk has
+   acknowledged receiving the data.
+   Internally synchronizes accesses to disks, so external
+   per-disk locking is unneeded. */
+static void
+ide_write (void *d_, block_sector_t sec_no, const void *buffer)
+{
+  struct ata_disk *d = d_;
+  struct channel *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);
+  lock_release (&c->lock);
+}
+
+static struct block_operations ide_operations =
+  {
+    ide_read,
+    ide_write
+  };
+
+/* 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 ata_disk *d, block_sector_t sec_no)
+{
+  struct channel *c = d->channel;
+
+  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 BLOCK_SECTOR_SIZE bytes. */
+static void
+input_sector (struct channel *c, void *sector) 
+{
+  insw (reg_data (c), sector, BLOCK_SECTOR_SIZE / 2);
+}
+
+/* Writes SECTOR to channel C's data register in PIO mode.
+   SECTOR must contain BLOCK_SECTOR_SIZE bytes. */
+static void
+output_sector (struct channel *c, const void *sector) 
+{
+  outsw (reg_data (c), sector, BLOCK_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 ata_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 ata_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 ata_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 ata_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 ();
+}
+
+