ide.c

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//ide.c - integrated device electronics driver
 
#include "ide.h"
#include "../io/io.h"
#include "../lib/err.h"
 
/**
 * @brief ideinit initializes the ide disk controller
 *
 * ideinit is a function that resets the ide controller, selects the master
 * drive, and verifies the drive is present and ready
 *
 * using ideinit is done with
 * @code{.c}
 * #include "../fs/ide.h" //or just ide.h
 * ideinit();
 * @endcode
 *
 * @see ffsinit(), irsec(), iwrt()
 */
void __ideinit(void) {
    //reset the ide controller
    outb(IDE_PRIMARY_CONTROL, 0x04); //assert reset
    for (int i = 0; i < 1000; i++) inb(IDE_STATUS); //short delay
    outb(IDE_PRIMARY_CONTROL, 0x00); //deassert reset
    for (int i = 0; i < 1000; i++) inb(IDE_STATUS); //short delay
    
    //select master drive
    outb(IDE_DEVICE, 0xA0);
    
    //wait for drive ready with timeout
    int timeout = 1000000;
    while ((inb(IDE_STATUS) & 0x80) && timeout--) {
        //wait
    }
    assert(timeout > 0, "ide: drive stuck busy");
    
    // check if drive exists
    uint8_t status = inb(IDE_STATUS);
    assert(status != 0xFF, "ide: no drive detected");
}
 
/**
 * @brief irsec reads a single 512 byte sector from disk
 *
 * irsec is a function that reads one sector from the ide drive at the given lba
 * @param lba, the logical block address to read from
 * @param buff, the 512 byte buffer to store the read data
 *
 * using irsec is done with
 * @code{.c}
 * #include "../fs/ide.h" //or just ide.h
 * uint8_t sector[512];
 * irsec(0, sector); //read the boot sector
 * @endcode
 *
 * @see iwrt(), idesize()
 */
void __irsec(uint32_t lba, uint8_t *buff) {
    assert(buff != NULL, "irsec: buffer is NULL");
    //wait for drive to be ready (not busy)
    while (inb(IDE_STATUS) & 0x80);
    
    //select drive and send lba
    outb(IDE_DEVICE, 0xE0 | ((lba >> 24) & 0x0F));
    outb(IDE_SECTORS, 1); //one sector
    outb(IDE_LBA_LOW, (uint8_t)lba);
    outb(IDE_LBA_MID, (uint8_t)(lba >> 8));
    outb(IDE_LBA_HIGH, (uint8_t)(lba >> 16));
    
    //read cmd
    outb(IDE_COMMAND, 0x20);
    
    //wait for data ready
    while (!(inb(IDE_STATUS) & 0x08));
    
    //read 256 words (512 bytes) from data port
    for (int i = 0; i < 256; i++) {
        ((uint16_t*)buff)[i] = inw(IDE_DATA); //warn: inw not inb be careful
    }
}
 
/**
 * @brief iwrt writes a single 512 byte sector to disk
 *
 * iwrt is a function that writes one sector to the ide drive at the given lba
 * @param lba, the logical block address to write to
 * @param buff, the 512 byte buffer containing the data to write
 *
 * using iwrt is done with
 * @code{.c}
 * #include "../fs/ide.h" //or just ide.h
 * uint8_t sector[512];
 * iwrt(1, sector); //write to sector 1
 * @endcode
 *
 * @see irsec(), fswrite()
 */
void __iwrt(uint32_t lba, uint8_t *buff) {
    assert(buff != NULL, "iwrt: buffer is NULL");
    //wait for drive to be ready
    while (inb(IDE_STATUS) & 0x80);
    
    //select drive and send lba
    outb(IDE_DEVICE, 0xE0 | ((lba >> 24) & 0x0F)); //calculate for out
    outb(IDE_SECTORS, 1);
    outb(IDE_LBA_LOW, (uint8_t)lba); //shifts, low is normal, mid is shfl 8, high is shfl 16
    outb(IDE_LBA_MID, (uint8_t)(lba >> 8));
    outb(IDE_LBA_HIGH, (uint8_t)(lba >> 16));
    
    //write command
    outb(IDE_COMMAND, 0x30);
    
    //wait for drive ready for data
    while (!(inb(IDE_STATUS) & 0x08));
    
    //write 256 words
    for (int i = 0; i < 256; i++) {
        outw(IDE_DATA, ((uint16_t*)buff)[i]);
    }
    
    //wait for write to complete
    while (inb(IDE_STATUS) & 0x80);
}
 
/**
 * @brief idesize queries the ide drive for its total sector count
 *
 * idesize is a function that sends the IDENTIFY command to the ide drive
 * and reads back the total number of lba28 sectors
 * @param secs, a pointer to store the total sector count
 *
 * using idesize is done with
 * @code{.c}
 * #include "../fs/ide.h" //or just ide.h
 * uint32_t total_secs;
 * if (idesize(&total_secs)) {
 *     //total_secs now holds the drive sector count
 * }
 * @endcode
 *
 * @see disksize(), ideinit()
 */
int __idesize(uint32_t *secs) {
    //wait for drive ready
    while (inb(IDE_STATUS) & 0x80);
    
    //select drive
    outb(IDE_DEVICE, 0xA0);
    
    //send IDENTIFY cmd (0xEC)
    outb(IDE_COMMAND, 0xEC);
    
    //wait for drq or err
    uint8_t status;
    int timeout = 1000000;
    do {
        status = inb(IDE_STATUS);
        if (status & 0x01) return 0; //error
        timeout--; //decrement timeout to actually wait
    } while (!(status & 0x08) && timeout > 0);
    
    if (timeout == 0) return 0;
    
    //read 256 words of identify data
    uint16_t identify[256];
    for (int i = 0; i < 256; i++) {
        identify[i] = inw(IDE_DATA);
    }
    
    //lba28 sectors are at words 60-61 (28 bit)
    //for lba28
    *secs = identify[60] | (identify[61] << 16);
    
    return 1; //success
}