system76_ec: Improve performance

Change-Id: I4c35dd70067d78c3eded549de1a37ded6db3d364

src/drivers/system76_ec/system76_ec.c

@@ -4,46 +4,46 @@
 
 #define SYSTEM76_EC_BASE 0x0E00
 
-static uint8_t system76_ec_read(uint8_t addr) {
+static inline uint8_t system76_ec_read(uint8_t addr) {
     return inb(SYSTEM76_EC_BASE + (uint16_t)addr);
 }
 
-static void system76_ec_write(uint8_t addr, uint8_t data) {
+static inline void system76_ec_write(uint8_t addr, uint8_t data) {
     outb(data, SYSTEM76_EC_BASE + (uint16_t)addr);
 }
 
-int system76_ec_print(uint8_t *buf, size_t len) {
-    size_t i;
-    for (i=0; i < len;) {
-        if (system76_ec_read(0) == 0) {
-            size_t j;
-            for (j=0; (i < len) && ((j + 4) < 256); i++, j++) {
-                system76_ec_write((uint8_t)(j + 4), buf[i]);
-            }
-            // Flags
-            system76_ec_write(2, 0);
-            // Length
-            system76_ec_write(3, (uint8_t)j);
-            // Command
-            system76_ec_write(0, 4);
-            // Wait for command completion, for up to 1 second
-            int timeout;
-            for (timeout = 1000000; timeout > 0; timeout--) {
-                if (system76_ec_read(0) == 0) break;
-                udelay(1);
-            }
-            if (timeout == 0) {
-                // Error: timeout occured
-                return -1;
-            }
-            if (system76_ec_read(1) != 0) {
-                // Error: command failed
-                return -1;
-            }
-        } else {
-            // Error: command is already running
-            return -1;
-        }
+void system76_ec_init(void) {
+    // Clear entire command region
+    for (int i = 0; i < 256; i++) {
+        system76_ec_write((uint8_t)i, 0);
+    }
+}
+
+void system76_ec_flush(void) {
+    // Send command
+    system76_ec_write(0, 4);
+
+    // Wait for command completion, for up to 1 second
+    int timeout;
+    for (timeout = 1000000; timeout > 0; timeout--) {
+        if (system76_ec_read(0) == 0) break;
+        udelay(1);
+    }
+
+    // Clear length
+    system76_ec_write(3, 0);
+}
+
+void system76_ec_print(uint8_t byte) {
+    // Read length
+    uint8_t len = system76_ec_read(3);
+    // Write data at offset
+    system76_ec_write(len + 4, byte);
+    // Update length
+    system76_ec_write(3, len + 1);
+
+    // If we hit the end of the buffer, or were given a newline, flush
+    if (byte == '\n' || len >= 128) {
+        system76_ec_flush();
     }
-    return (int)i;
 }