Use mutex for EC->PD host commands

Host commands can be generated by either the PDCMD task (in response
to PD interrupts), or the HOSTCMD task (in response to passthru
requests).  Use a mutex to serialize access to the EC->PD interface.

BUG=chrome-os-partner:30079
BRANCH=none
TEST=Boot samus

Change-Id: If65d5eb4bbef91e6c811a06ea2e1487e17143dc7
Signed-off-by: Randall Spangler <rspangler@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/210401
Reviewed-by: Bill Richardson <wfrichar@chromium.org>
Reviewed-by: Alec Berg <alecaberg@chromium.org>

1 files changed, 28 insertions, 6 deletions

diff --git a/common/host_command_master.c b/common/host_command_master.c
index 23441d0a3a..15748d4e82 100644
--- a/common/host_command_master.c
+++ b/common/host_command_master.c
@@ -9,6 +9,7 @@
 #include "console.h"
 #include "host_command.h"
 #include "i2c.h"
+#include "task.h"
 #include "timer.h"
 #include "util.h"
 
@@ -19,14 +20,16 @@
 /* Host command timeout */
 #define HOST_COMMAND_TIMEOUT_US SECOND
 
-/*
- * Sends a command to the PD (protocol v3).
+static struct mutex pd_mutex;
+
+/**
+ * Non-task-safe internal version of pd_host_command().
  *
- * Returns >= 0 for success, or negative if error.
+ * Do not call this version directly!  Use pd_host_command().
  */
-int pd_host_command(int command, int version,
-		    const void *outdata, int outsize,
-		    void *indata, int insize)
+static int pd_host_command_internal(int command, int version,
+				    const void *outdata, int outsize,
+				    void *indata, int insize)
 {
 	int ret, i;
 	int resp_len;
@@ -149,6 +152,25 @@ int pd_host_command(int command, int version,
 	return resp_len;
 }
 
+int pd_host_command(int command, int version,
+		    const void *outdata, int outsize,
+		    void *indata, int insize)
+{
+	int rv;
+
+	/* Acquire mutex */
+	mutex_lock(&pd_mutex);
+
+	/* Call internal version of host command */
+	rv = pd_host_command_internal(command, version, outdata, outsize,
+				      indata, insize);
+
+	/* Release mutex */
+	mutex_unlock(&pd_mutex);
+
+	return rv;
+}
+
 static int command_pd_mcu(int argc, char **argv)
 {
 	char *e;