github.com/icexin/eggos@v0.4.2-0.20220216025428-78b167e4f349/drivers/pic/pic.go (about)

     1  package pic
     2  
     3  import "github.com/icexin/eggos/kernel/sys"
     4  
     5  const (
     6  	PIC1_CMD  = 0x20
     7  	PIC1_DATA = PIC1_CMD + 1
     8  	PIC2_CMD  = 0xA0
     9  	PIC2_DATA = PIC2_CMD + 1
    10  
    11  	ICW4_8086 = 0x01 /* 8086/88 (MCS-80/85) mode */
    12  	ICW4_AUTO = 0x02 /* Auto (normal) EOI */
    13  
    14  	IRQ_BASE = 0x20
    15  
    16  	LINE_TIMER = 0
    17  	LINE_KBD   = 1
    18  	LINE_COM1  = 4
    19  	LINE_COM2  = 3
    20  	LINE_MOUSE = 12
    21  )
    22  
    23  //go:nosplit
    24  func Init() {
    25  	// send init command
    26  	sys.Outb(PIC1_CMD, 0x11)
    27  	sys.Outb(PIC2_CMD, 0x11)
    28  
    29  	// set offset
    30  	sys.Outb(PIC1_DATA, IRQ_BASE)
    31  	sys.Outb(PIC2_DATA, IRQ_BASE+8)
    32  
    33  	// set master and slave chip
    34  	sys.Outb(PIC1_DATA, 0x4)
    35  	sys.Outb(PIC2_DATA, 0x2)
    36  
    37  	sys.Outb(PIC1_DATA, ICW4_8086)
    38  	sys.Outb(PIC2_DATA, ICW4_8086)
    39  	// sys.Outb(PIC1_DATA, ICW4_8086|ICW4_AUTO)
    40  	// sys.Outb(PIC2_DATA, ICW4_8086|ICW4_AUTO)
    41  
    42  	// disable all ints
    43  	sys.Outb(PIC1_DATA, 0xff)
    44  	sys.Outb(PIC2_DATA, 0xff)
    45  
    46  	// Enable slave intr pin on master
    47  	EnableIRQ(0x02)
    48  }
    49  
    50  //go:nosplit
    51  func EnableIRQ(line uint16) {
    52  	var port uint16 = PIC1_DATA
    53  	if line >= 8 {
    54  		port = PIC2_DATA
    55  		line -= 8
    56  	}
    57  	sys.Outb(port, byte(sys.Inb(port)&^(1<<line)))
    58  }
    59  
    60  //go:nosplit
    61  func DisableIRQ(line uint16) {
    62  	var port uint16 = PIC1_DATA
    63  	if line >= 8 {
    64  		port = PIC2_DATA
    65  		line -= 8
    66  	}
    67  	sys.Outb(port, byte(sys.Inb(port)|(1<<line)))
    68  }
    69  
    70  //go:nosplit
    71  func EOI(irq uintptr) {
    72  	if irq >= 0x28 {
    73  		sys.Outb(PIC2_CMD, 0x20)
    74  	}
    75  	sys.Outb(PIC1_CMD, 0x20)
    76  }