linux-kernel - [PATCH v4 3/5] platform/chrome: cros_ec_proto: Introduce cros_ec_get_cmd

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Message-Id: <20240616-cros_ec-charge-control-v4-3-74d649a9117d@weissschuh.net>
Date: Sun, 16 Jun 2024 21:03:31 +0200
From: Thomas Weißschuh <linux@...ssschuh.net>
To: Benson Leung <bleung@...omium.org>, Guenter Roeck <groeck@...omium.org>, 
 Sebastian Reichel <sre@...nel.org>, 
 Thomas Weißschuh <thomas@...ssschuh.net>, 
 "Rafael J. Wysocki" <rafael@...nel.org>, Len Brown <lenb@...nel.org>, 
 Robert Moore <robert.moore@...el.com>, Tzung-Bi Shih <tzungbi@...nel.org>
Cc: chrome-platform@...ts.linux.dev, linux-kernel@...r.kernel.org, 
 linux-pm@...r.kernel.org, Mario Limonciello <mario.limonciello@....com>, 
 Dustin Howett <dustin@...ett.net>, 
 Stephen Horvath <s.horvath@...look.com.au>, 
 Rajas Paranjpe <paranjperajas@...il.com>, linux-acpi@...r.kernel.org, 
 acpica-devel@...ts.linux.dev, Matt Hartley <matt.hartley@...il.com>, 
 Thomas Weißschuh <linux@...ssschuh.net>
Subject: [PATCH v4 3/5] platform/chrome: cros_ec_proto: Introduce
 cros_ec_get_cmd_versions()

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@...ssschuh.net>
---
 drivers/platform/chrome/cros_ec_proto.c     | 35 +++++++++++++++++++++++++++++
 include/linux/platform_data/cros_ec_proto.h |  2 ++
 2 files changed, 37 insertions(+)

diff --git a/drivers/platform/chrome/cros_ec_proto.c b/drivers/platform/chrome/cros_ec_proto.c
index fe68be66ee98..f776fd42244f 100644
--- a/drivers/platform/chrome/cros_ec_proto.c
+++ b/drivers/platform/chrome/cros_ec_proto.c
@@ -5,6 +5,7 @@

 #include <linux/delay.h>
 #include <linux/device.h>
+#include <linux/limits.h>
 #include <linux/module.h>
 #include <linux/platform_data/cros_ec_commands.h>
 #include <linux/platform_data/cros_ec_proto.h>
@@ -1069,3 +1070,37 @@ 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_get_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_get_cmd_versions(struct cros_ec_device *ec_dev, u16 cmd)
+{
+	struct ec_params_get_cmd_versions req_v0;
+	struct ec_params_get_cmd_versions_v1 req_v1;
+	struct ec_response_get_cmd_versions resp;
+	int ret;
+
+	if (cmd <= U8_MAX) {
+		req_v0.cmd = cmd;
+		ret = cros_ec_cmd(ec_dev, 0, EC_CMD_GET_CMD_VERSIONS,
+				  &req_v0, sizeof(req_v0), &resp, sizeof(resp));
+	} else {
+		req_v1.cmd = cmd;
+		ret = cros_ec_cmd(ec_dev, 1, EC_CMD_GET_CMD_VERSIONS,
+				  &req_v1, sizeof(req_v1), &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_get_cmd_versions);
diff --git a/include/linux/platform_data/cros_ec_proto.h b/include/linux/platform_data/cros_ec_proto.h
index 6e9225bdf903..b34ed0cc1f8d 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_get_cmd_versions(struct cros_ec_device *ec_dev, u16 cmd);
+
 /**
  * cros_ec_get_time_ns() - Return time in ns.
  *

-- 
2.45.2