System76 EC console support

Change-Id: I04c2aeb19d780a7c6638b502192fa9f569e32e94

src/console/Kconfig

@@ -302,6 +302,13 @@ config SPI_CONSOLE
 	  This is currently working only in ramstage due to how the spi
 	  drivers are written.
 
+config CONSOLE_SYSTEM76_EC
+	bool "System76 EC console output"
+	default y
+	depends on DRIVERS_SYSTEM76_EC
+	help
+	  Send coreboot debug output to a System76 embedded controller.
+
 config CONSOLE_OVERRIDE_LOGLEVEL
 	bool
 	help

src/console/console.c

@@ -20,6 +20,7 @@
 #include <console/usb.h>
 #include <console/spi.h>
 #include <console/flash.h>
+#include <console/system76_ec.h>
 
 void console_hw_init(void)
 {
@@ -53,6 +54,7 @@ void console_tx_byte(unsigned char byte)
 	__usb_tx_byte(byte);
 	__spiconsole_tx_byte(byte);
 	__flashconsole_tx_byte(byte);
+	__system76_ec_tx_byte(byte);
 }
 
 void console_tx_flush(void)

src/drivers/system76_ec/Kconfig

@@ -0,0 +1,2 @@
+config DRIVERS_SYSTEM76_EC
+	bool

src/drivers/system76_ec/Makefile.inc

@@ -0,0 +1,10 @@
+ifeq ($(CONFIG_DRIVERS_SYSTEM76_EC),y)
+
+bootblock-y += system76_ec.c
+verstage-y += system76_ec.c
+romstage-y += system76_ec.c
+postcar-y += system76_ec.c
+ramstage-y += system76_ec.c
+smm-$(CONFIG_DEBUG_SMI) += system76_ec.c
+
+endif

src/drivers/system76_ec/system76_ec.c

@@ -0,0 +1,49 @@
+#include <arch/io.h>
+#include <console/system76_ec.h>
+#include <delay.h>
+
+#define SYSTEM76_EC_BASE 0x0E00
+
+static 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) {
+    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;
+        }
+    }
+    return (int)i;
+}

src/include/console/system76_ec.h

@@ -0,0 +1,21 @@
+#ifndef CONSOLE_SYSTEM76_EC_H
+#define CONSOLE_SYSTEM76_EC_H 1
+
+#include <stddef.h>
+#include <stdint.h>
+
+int system76_ec_print(uint8_t *buf, size_t len);
+
+#define __CONSOLE_SYSTEM76_EC_ENABLE__	(CONFIG(CONSOLE_SYSTEM76_EC) && \
+	(ENV_BOOTBLOCK || ENV_ROMSTAGE || ENV_RAMSTAGE || ENV_VERSTAGE || \
+	ENV_POSTCAR || (ENV_SMM && CONFIG(DEBUG_SMI))))
+
+#if __CONSOLE_SYSTEM76_EC_ENABLE__
+static inline void __system76_ec_tx_byte(unsigned char byte) {
+	system76_ec_print(&byte, 1);
+}
+#else
+static inline void __system76_ec_tx_byte(unsigned char byte) {}
+#endif
+
+#endif