Create ps2.c

add initial ps/2 driver code. This will need wired up to be used

kernel/ps2.c

@@ -0,0 +1,117 @@
+#include "ps2.h"
+
+/* --- Low Level I/O Helpers --- */
+static inline void outb(uint16_t port, uint8_t val) {
+    asm volatile ("outb %0, %1" : : "a"(val), "Nd"(port));
+}
+
+static inline uint8_t inb(uint16_t port) {
+    uint8_t ret;
+    asm volatile ("inb %1, %0" : "=a"(ret) : "Nd"(port));
+    return ret;
+}
+
+/* --- Controller Synchronization --- */
+
+// Wait until the controller is ready to receive a byte
+static void ps2_wait_write() {
+    while (inb(PS2_STATUS_REG) & PS2_STATUS_INPUT);
+}
+
+// Wait until the controller has a byte for us to read
+static void ps2_wait_read() {
+    while (!(inb(PS2_STATUS_REG) & PS2_STATUS_OUTPUT));
+}
+
+/* --- Initialization --- */
+
+void ps2_write_device(uint8_t command) {
+    ps2_wait_write();
+    outb(PS2_DATA_PORT, command);
+}
+
+void ps2_write_mouse(uint8_t data) {
+    ps2_wait_write();
+    outb(PS2_COMMAND_REG, PS2_CMD_WRITE_MOUSE); // "Next byte goes to mouse"
+    ps2_wait_write();
+    outb(PS2_DATA_PORT, data);
+}
+
+void ps2_init(void) {
+    // 1. Disable Devices
+    ps2_wait_write();
+    outb(PS2_COMMAND_REG, PS2_CMD_DISABLE_KB);
+    ps2_wait_write();
+    outb(PS2_COMMAND_REG, PS2_CMD_DISABLE_MS);
+
+    // 2. Flush Output Buffer
+    while (inb(PS2_STATUS_REG) & PS2_STATUS_OUTPUT) {
+        inb(PS2_DATA_PORT);
+    }
+
+    // 3. Set Controller Configuration Byte
+    // Bit 0: KB Interrupt, Bit 1: Mouse Interrupt, Bit 6: Translation
+    ps2_wait_write();
+    outb(PS2_COMMAND_REG, PS2_CMD_READ_CONFIG);
+    ps2_wait_read();
+    uint8_t status = inb(PS2_DATA_PORT);
+    status |= (1 << 0) | (1 << 1); // Enable IRQ 1 and IRQ 12
+    
+    ps2_wait_write();
+    outb(PS2_COMMAND_REG, PS2_CMD_WRITE_CONFIG);
+    ps2_wait_write();
+    outb(PS2_DATA_PORT, status);
+
+    // 4. Enable Devices
+    ps2_wait_write();
+    outb(PS2_COMMAND_REG, PS2_CMD_ENABLE_KB);
+    ps2_wait_write();
+    outb(PS2_COMMAND_REG, PS2_CMD_ENABLE_MS);
+
+    // 5. Initialize Mouse (The mouse won't send IRQs until you tell it to)
+    ps2_write_mouse(MOUSE_CMD_SET_DEFAULTS);
+    ps2_wait_read(); inb(PS2_DATA_PORT); // Read ACK (0xFA)
+    
+    ps2_write_mouse(MOUSE_CMD_ENABLE_SCAN);
+    ps2_wait_read(); inb(PS2_DATA_PORT); // Read ACK (0xFA)
+}
+
+/* --- IRQ Handlers --- */
+
+// Called from IRQ 1 (Keyboard)
+void ps2_keyboard_handler(void) {
+    uint8_t scancode = inb(PS2_DATA_PORT);
+    // Process scancode (e.g., put it into a circular buffer)
+}
+
+// Called from IRQ 12 (Mouse)
+static uint8_t mouse_cycle = 0;
+static uint8_t mouse_bytes[3];
+
+void ps2_mouse_handler(void) {
+    uint8_t status = inb(PS2_STATUS_REG);
+    
+    // Ensure this is actually mouse data
+    if (!(status & PS2_STATUS_MOUSE)) return;
+
+    mouse_bytes[mouse_cycle++] = inb(PS2_DATA_PORT);
+
+    if (mouse_cycle == 3) {
+        mouse_cycle = 0;
+        
+        // Byte 0: Flags (Buttons, Signs)
+        // Byte 1: X Delta
+        // Byte 2: Y Delta
+        
+        mouse_state_t state;
+        state.left_button   = (mouse_bytes[0] & 0x01);
+        state.right_button  = (mouse_bytes[0] & 0x02);
+        state.middle_button = (mouse_bytes[0] & 0x04);
+
+        // Handle negative deltas (signed 9-bit logic)
+        state.x_delta = (int8_t)mouse_bytes[1];
+        state.y_delta = (int8_t)mouse_bytes[2];
+
+        // Update your kernel's internal mouse position here
+    }
+}

kernel/ps2.h

@@ -0,0 +1,45 @@
+#ifndef PS2_H
+#define PS2_H
+
+#include <stdint.h>
+#include <stdbool.h>
+
+/* I/O Ports */
+#define PS2_DATA_PORT       0x60
+#define PS2_STATUS_REG      0x64
+#define PS2_COMMAND_REG     0x64
+
+/* Status Register Bits */
+#define PS2_STATUS_OUTPUT   0x01 // 1 = Data ready to be read
+#define PS2_STATUS_INPUT    0x02 // 1 = Controller busy, don't write yet
+#define PS2_STATUS_SYS      0x04 // System flag
+#define PS2_STATUS_CMD_DATA 0x08 // 0 = Data written to 0x60, 1 = Cmd to 0x64
+#define PS2_STATUS_MOUSE    0x20 // 1 = Mouse data, 0 = Keyboard data
+
+/* Controller Commands */
+#define PS2_CMD_READ_CONFIG  0x20
+#define PS2_CMD_WRITE_CONFIG 0x60
+#define PS2_CMD_DISABLE_MS   0xA7
+#define PS2_CMD_ENABLE_MS    0xA8
+#define PS2_CMD_DISABLE_KB   0xAD
+#define PS2_CMD_ENABLE_KB    0xAE
+#define PS2_CMD_WRITE_MOUSE  0xD4
+
+/* Mouse Commands */
+#define MOUSE_CMD_SET_DEFAULTS 0xF6
+#define MOUSE_CMD_ENABLE_SCAN  0xF4
+
+typedef struct {
+    int8_t  x_delta;
+    int8_t  y_delta;
+    bool    left_button;
+    bool    right_button;
+    bool    middle_button;
+} mouse_state_t;
+
+/* Public API */
+void ps2_init(void);
+void ps2_keyboard_handler(void);
+void ps2_mouse_handler(void);
+
+#endif