cros_ec: i2c: Add support for version 3 of the EC protocol

Add support for version 3 of the ec protocol. It basically works by
stitching some additional header in front (special command code),
and having a result and packet_length stitched on for the reply.

Signed-off-by: Moritz Fischer <moritz.fischer@ettus.com>
Cc: Simon Glass <sjg@chromium.org>
Cc: u-boot@lists.denx.de
Acked-by: Simon Glass <sjg@chromium.org>
Tested on snow:
Tested-by: Simon Glass <sjg@chromium.org>

diff --git a/drivers/misc/cros_ec_i2c.c b/drivers/misc/cros_ec_i2c.c
index f2f6961499bc2ddb0f52cab1ce0cc8d5b3054e1b..6e0934017a3eeec20dd71fb8738958666beb02c1 100644 (file)
--- a/drivers/misc/cros_ec_i2c.c
+++ b/drivers/misc/cros_ec_i2c.c
@@ -24,6 +24,89 @@
 #define debug_trace(fmt, b...)
 #endif
 
+/**
+ * Request format for protocol v3
+ * byte 0      0xda (EC_COMMAND_PROTOCOL_3)
+ * byte 1-8    struct ec_host_request
+ * byte 10-    response data
+ */
+struct ec_host_request_i2c {
+       /* Always 0xda to backward compatible with v2 struct */
+       uint8_t  command_protocol;
+       struct ec_host_request ec_request;
+} __packed;
+
+/*
+ * Response format for protocol v3
+ * byte 0      result code
+ * byte 1      packet_length
+ * byte 2-9    struct ec_host_response
+ * byte 10-    response data
+ */
+struct ec_host_response_i2c {
+       uint8_t result;
+       uint8_t packet_length;
+       struct ec_host_response ec_response;
+} __packed;
+
+static int cros_ec_i2c_packet(struct udevice *udev, int out_bytes, int in_bytes)
+{
+       struct cros_ec_dev *dev = dev_get_uclass_priv(udev);
+       struct dm_i2c_chip *chip = dev_get_parent_platdata(udev);
+       struct ec_host_request_i2c *ec_request_i2c =
+               (struct ec_host_request_i2c *)dev->dout;
+       struct ec_host_response_i2c *ec_response_i2c =
+               (struct ec_host_response_i2c *)dev->din;
+       struct i2c_msg i2c_msg[2];
+       int ret;
+
+       i2c_msg[0].addr = chip->chip_addr;
+       i2c_msg[0].flags = 0;
+       i2c_msg[1].addr = chip->chip_addr;
+       i2c_msg[1].flags = I2C_M_RD;
+
+       /* one extra byte, to indicate v3 */
+       i2c_msg[0].len = out_bytes + 1;
+       i2c_msg[0].buf = dev->dout;
+
+       /* stitch on EC_COMMAND_PROTOCOL_3 */
+       memmove(&ec_request_i2c->ec_request, dev->dout, out_bytes);
+       ec_request_i2c->command_protocol = EC_COMMAND_PROTOCOL_3;
+
+       /* two extra bytes for v3 */
+       i2c_msg[1].len = in_bytes + 2;
+       i2c_msg[1].buf = dev->din;
+
+       ret = dm_i2c_xfer(udev, &i2c_msg[0], 2);
+       if (ret) {
+               printf("%s: Could not execute transfer: %d\n", __func__, ret);
+               return ret;
+       }
+
+       /* When we send a v3 request to v2 ec, ec won't recognize the 0xda
+        * (EC_COMMAND_PROTOCOL_3) and will return with status
+        * EC_RES_INVALID_COMMAND with zero data length
+        *
+        * In case of invalid command for v3 protocol the data length
+        * will be at least sizeof(struct ec_host_response)
+        */
+       if (ec_response_i2c->result == EC_RES_INVALID_COMMAND &&
+           ec_response_i2c->packet_length == 0)
+               return -EPROTONOSUPPORT;
+
+       if (ec_response_i2c->packet_length < sizeof(struct ec_host_response)) {
+               printf("%s: response of %u bytes too short; not a full hdr\n",
+                      __func__, ec_response_i2c->packet_length);
+               return -EBADMSG;
+       }
+
+
+       /* drop result and packet_len */
+       memmove(dev->din, &ec_response_i2c->ec_response, in_bytes);
+
+       return in_bytes;
+}
+
 static int cros_ec_i2c_command(struct udevice *udev, uint8_t cmd,
                               int cmd_version, const uint8_t *dout,
                               int dout_len, uint8_t **dinp, int din_len)
@@ -140,6 +223,7 @@ static int cros_ec_probe(struct udevice *dev)
 
 static struct dm_cros_ec_ops cros_ec_ops = {
        .command = cros_ec_i2c_command,
+       .packet = cros_ec_i2c_packet,
 };
 
 static const struct udevice_id cros_ec_ids[] = {