mfd: cros_ec: Use fixed size arrays to transfer data with the EC

The struct cros_ec_command will be used as an ioctl() argument for the
API to control the ChromeOS EC from user-space. So the data structure
has to be 64-bit safe to make it compatible between 32 and 64 avoiding
the need for a compat ioctl interface. Since pointers are self-aligned
to different byte boundaries, use fixed size arrays instead of pointers
for transferring ingoing and outgoing data with the Embedded Controller.

Also, re-arrange struct members by decreasing alignment requirements to
reduce the needing padding size.

Signed-off-by: Javier Martinez Canillas <javier.martinez@collabora.co.uk>
Acked-by: Lee Jones <lee.jones@linaro.org>
Tested-by: Gwendal Grignou <gwendal@chromium.org>
Reviewed-by: Gwendal Grignou <gwendal@chromium.org>
Signed-off-by: Olof Johansson <olof@lixom.net>

4 files changed, 29 insertions, 58 deletions

diff --git a/drivers/i2c/busses/i2c-cros-ec-tunnel.c b/drivers/i2c/busses/i2c-cros-ec-tunnel.c
index 875c22ae5400..fa8dedd8c3a2 100644
--- a/drivers/i2c/busses/i2c-cros-ec-tunnel.c
+++ b/drivers/i2c/busses/i2c-cros-ec-tunnel.c
@@ -182,72 +182,41 @@ static int ec_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg i2c_msgs[],
         const u16 bus_num = bus->remote_bus;
         int request_len;
         int response_len;
-        u8 *request = NULL;
-        u8 *response = NULL;
         int result;
-        struct cros_ec_command msg;
+        struct cros_ec_command msg = { };
 
         request_len = ec_i2c_count_message(i2c_msgs, num);
         if (request_len < 0) {
                 dev_warn(dev, "Error constructing message %d\n", request_len);
-                result = request_len;
-                goto exit;
+                return request_len;
         }
+
         response_len = ec_i2c_count_response(i2c_msgs, num);
         if (response_len < 0) {
                 /* Unexpected; no errors should come when NULL response */
                 dev_warn(dev, "Error preparing response %d\n", response_len);
-                result = response_len;
-                goto exit;
-        }
-
-        if (request_len <= ARRAY_SIZE(bus->request_buf)) {
-                request = bus->request_buf;
-        } else {
-                request = kzalloc(request_len, GFP_KERNEL);
-                if (request == NULL) {
-                        result = -ENOMEM;
-                        goto exit;
-                }
-        }
-        if (response_len <= ARRAY_SIZE(bus->response_buf)) {
-                response = bus->response_buf;
-        } else {
-                response = kzalloc(response_len, GFP_KERNEL);
-                if (response == NULL) {
-                        result = -ENOMEM;
-                        goto exit;
-                }
+                return response_len;
         }
 
-        result = ec_i2c_construct_message(request, i2c_msgs, num, bus_num);
+        result = ec_i2c_construct_message(msg.outdata, i2c_msgs, num, bus_num);
         if (result)
-                goto exit;
+                return result;
 
         msg.version = 0;
         msg.command = EC_CMD_I2C_PASSTHRU;
-        msg.outdata = request;
         msg.outsize = request_len;
-        msg.indata = response;
         msg.insize = response_len;
 
         result = cros_ec_cmd_xfer(bus->ec, &msg);
         if (result < 0)
-                goto exit;
+                return result;
 
-        result = ec_i2c_parse_response(response, i2c_msgs, &num);
+        result = ec_i2c_parse_response(msg.indata, i2c_msgs, &num);
         if (result < 0)
-                goto exit;
+                return result;
 
         /* Indicate success by saying how many messages were sent */
-        result = num;
-exit:
-        if (request != bus->request_buf)
-                kfree(request);
-        if (response != bus->response_buf)
-                kfree(response);
-
-        return result;
+        return num;
 }
 
 static u32 ec_i2c_functionality(struct i2c_adapter *adap)
diff --git a/drivers/input/keyboard/cros_ec_keyb.c b/drivers/input/keyboard/cros_ec_keyb.c
index ffa989f2c785..769f8f7f62b7 100644
--- a/drivers/input/keyboard/cros_ec_keyb.c
+++ b/drivers/input/keyboard/cros_ec_keyb.c
@@ -148,16 +148,19 @@ static void cros_ec_keyb_process(struct cros_ec_keyb *ckdev,
 
 static int cros_ec_keyb_get_state(struct cros_ec_keyb *ckdev, uint8_t *kb_state)
 {
+        int ret;
         struct cros_ec_command msg = {
-                .version = 0,
                 .command = EC_CMD_MKBP_STATE,
-                .outdata = NULL,
-                .outsize = 0,
-                .indata = kb_state,
                 .insize = ckdev->cols,
         };
 
-        return cros_ec_cmd_xfer(ckdev->ec, &msg);
+        ret = cros_ec_cmd_xfer(ckdev->ec, &msg);
+        if (ret < 0)
+                return ret;
+
+        memcpy(kb_state, msg.indata, ckdev->cols);
+
+        return 0;
 }
 
 static irqreturn_t cros_ec_keyb_irq(int irq, void *data)
diff --git a/drivers/mfd/cros_ec.c b/drivers/mfd/cros_ec.c
index fc0c81ef04ff..c872e1b0eaf8 100644
--- a/drivers/mfd/cros_ec.c
+++ b/drivers/mfd/cros_ec.c
@@ -74,15 +74,11 @@ int cros_ec_cmd_xfer(struct cros_ec_device *ec_dev,
         ret = ec_dev->cmd_xfer(ec_dev, msg);
         if (msg->result == EC_RES_IN_PROGRESS) {
                 int i;
-                struct cros_ec_command status_msg;
-                struct ec_response_get_comms_status status;
+                struct cros_ec_command status_msg = { };
+                struct ec_response_get_comms_status *status;
 
-                status_msg.version = 0;
                 status_msg.command = EC_CMD_GET_COMMS_STATUS;
-                status_msg.outdata = NULL;
-                status_msg.outsize = 0;
-                status_msg.indata = (uint8_t *)&status;
-                status_msg.insize = sizeof(status);
+                status_msg.insize = sizeof(*status);
 
                 /*
                  * Query the EC's status until it's no longer busy or
@@ -98,7 +94,10 @@ int cros_ec_cmd_xfer(struct cros_ec_device *ec_dev,
                         msg->result = status_msg.result;
                         if (status_msg.result != EC_RES_SUCCESS)
                                 break;
-                        if (!(status.flags & EC_COMMS_STATUS_PROCESSING))
+
+                        status = (struct ec_response_get_comms_status *)
+                                 status_msg.indata;
+                        if (!(status->flags & EC_COMMS_STATUS_PROCESSING))
                                 break;
                 }
         }
diff --git a/include/linux/mfd/cros_ec.h b/include/linux/mfd/cros_ec.h
index 0e166b92f5b4..71675b14b5ca 100644
--- a/include/linux/mfd/cros_ec.h
+++ b/include/linux/mfd/cros_ec.h
@@ -38,20 +38,20 @@ enum {
 /*
  * @version: Command version number (often 0)
  * @command: Command to send (EC_CMD_...)
- * @outdata: Outgoing data to EC
  * @outsize: Outgoing length in bytes
- * @indata: Where to put the incoming data from EC