Enable PNP devices by default, attempt to send/receive data from touchpad

src/ec/it8587e/include/ec/ps2.h

@@ -14,6 +14,9 @@ extern struct Ps2 __code PS2_1;
 extern struct Ps2 __code PS2_2;
 extern struct Ps2 __code PS2_3;
 
+int ps2_read(struct Ps2 * ps2, uint8_t * data, int length); 
+int ps2_write(struct Ps2 * ps2, uint8_t * data, int length);
+
 volatile uint8_t __xdata __at(0x1700) PSCTL1;
 volatile uint8_t __xdata __at(0x1701) PSCTL2;
 volatile uint8_t __xdata __at(0x1702) PSCTL3;

src/ec/it8587e/ps2.c

@@ -1,3 +1,6 @@
+#include <stdbool.h>
+
+#include <board/cpu.h>
 #include <ec/ps2.h>
 
 #define PS2(NUM) { \
@@ -7,6 +10,63 @@
     .data = &PSDAT ## NUM, \
 }
 
+#define TIMEOUT (F_CPU/1000)
+
+#define PSSTS_TIMEOUT_ERR (1 << 6)
+#define PSSTS_FRAME_ERR (1 << 5)
+#define PSSTS_PARITY_ERR (1 << 4)
+#define PSSTS_ALL_ERR (PSSTS_TIMEOUT_ERR | PSSTS_FRAME_ERR | PSSTS_PARITY_ERR)
+#define PSSTS_DONE (1 << 3)
+
 struct Ps2 __code PS2_1 = PS2(1);
 struct Ps2 __code PS2_2 = PS2(2);
 struct Ps2 __code PS2_3 = PS2(3);
+
+static int ps2_transaction(struct Ps2 * ps2, uint8_t * data, int length, bool read) {
+    int i;
+    for (i = 0; i < length; i++) {
+        if (read) {
+            // Begin read
+            *(ps2->control) = 0x07;
+        } else {
+            // Begin write
+            *(ps2->control) = 0x0D;
+            *(ps2->data) = data[i];
+            // Pull data line low
+            *(ps2->control) = 0x0C;
+            // Pull clock line high
+            *(ps2->control) = 0x0E;
+        }
+
+        uint32_t timeout;
+        for (timeout = TIMEOUT; timeout > 0; timeout--) {
+            uint8_t status = *(ps2->status);
+            // If an error happened, clear status and return the error
+            if (status & PSSTS_ALL_ERR) {
+                *(ps2->status) = status;
+                return -(int)status;
+            }
+            // If transaction is done, break
+            if (status & PSSTS_DONE) {
+                break;
+            }
+        }
+        // If a timeout happened, return the error
+        if (timeout == 0) {
+            return -1;
+        }
+        if (read) {
+            data[i] = *(ps2->data);
+        }
+    }
+
+    return i;
+}
+
+int ps2_read(struct Ps2 * ps2, uint8_t * data, int length) {
+    return ps2_transaction(ps2, data, length, true);
+}
+
+int ps2_write(struct Ps2 * ps2, uint8_t * data, int length) {
+    return ps2_transaction(ps2, data, length, false);
+}