[PATCH v3 3/5] platform/chrome: cros_ec_proto: Introduce cros_ec_cmd_versions()

[Thomas Weißschuh <linux@xxxxxxxxxxxxxx>]

Retrieving the supported versions of a command is a fairly common
operation. Provide a helper for it.

If the command is not supported at all the EC returns
-EINVAL/EC_RES_INVALID_PARAMS.

This error is translated into an empty version mask as that is easier to
handle for callers and they don't need to know about the error details.

Signed-off-by: Thomas Weißschuh <linux@xxxxxxxxxxxxxx>
---
 drivers/platform/chrome/cros_ec_proto.c     | 26 ++++++++++++++++++++++++++
 include/linux/platform_data/cros_ec_proto.h |  2 ++
 2 files changed, 28 insertions(+)

diff --git a/drivers/platform/chrome/cros_ec_proto.c b/drivers/platform/chrome/cros_ec_proto.c
index fe68be66ee98..9cfe885a5301 100644
--- a/drivers/platform/chrome/cros_ec_proto.c
+++ b/drivers/platform/chrome/cros_ec_proto.c
@@ -1069,3 +1069,29 @@ int cros_ec_cmd_readmem(struct cros_ec_device *ec_dev, u8 offset, u8 size, void
 			   &params, sizeof(params), dest, size);
 }
 EXPORT_SYMBOL_GPL(cros_ec_cmd_readmem);
+
+/**
+ * cros_ec_cmd_versions - Get supported version mask.
+ *
+ * @ec_dev: EC device
+ * @cmd: Command to test
+ *
+ * Return: version mask on success, negative error number on failure.
+ */
+int cros_ec_cmd_versions(struct cros_ec_device *ec_dev, u16 cmd)
+{
+	struct ec_params_get_cmd_versions_v1 req = {};
+	struct ec_response_get_cmd_versions resp;
+	int ret;
+
+	req.cmd = cmd;
+	ret = cros_ec_cmd(ec_dev, 1, EC_CMD_GET_CMD_VERSIONS,
+			  &req, sizeof(req), &resp, sizeof(resp));
+	if (ret == -EINVAL)
+		return 0; /* Command not implemented */
+	else if (ret < 0)
+		return ret;
+	else
+		return resp.version_mask;
+}
+EXPORT_SYMBOL_GPL(cros_ec_cmd_versions);
diff --git a/include/linux/platform_data/cros_ec_proto.h b/include/linux/platform_data/cros_ec_proto.h
index 6e9225bdf903..98ab5986f543 100644
--- a/include/linux/platform_data/cros_ec_proto.h
+++ b/include/linux/platform_data/cros_ec_proto.h
@@ -263,6 +263,8 @@ int cros_ec_cmd(struct cros_ec_device *ec_dev, unsigned int version, int command
 
 int cros_ec_cmd_readmem(struct cros_ec_device *ec_dev, u8 offset, u8 size, void *dest);
 
+int cros_ec_cmd_versions(struct cros_ec_device *ec_dev, u16 cmd);
+
 /**
  * cros_ec_get_time_ns() - Return time in ns.
  *

-- 
2.45.2