platform/chrome: wilco_ec: Add property helper library

A Property is typically a data item that is stored to NVRAM
by the EC. Each of these data items has an index associated
with it, known as the Property ID (PID). Properties may have
variable lengths, up to a max of WILCO_EC_PROPERTY_MAX_SIZE
bytes. Properties can be simple integers, or they may be more
complex binary data.

This patch adds support for getting and setting properties.
This will be useful for setting the charge algorithm and charge
schedules, which all use properties.

Signed-off-by: Nick Crews <ncrews@chromium.org>
Signed-off-by: Enric Balletbo i Serra <enric.balletbo@collabora.com>

2 files changed, 133 insertions, 1 deletions

diff --git a/drivers/platform/chrome/wilco_ec/Makefile b/drivers/platform/chrome/wilco_ec/Makefile
index 063e7fb4ea17..29b734137786 100644
--- a/drivers/platform/chrome/wilco_ec/Makefile
+++ b/drivers/platform/chrome/wilco_ec/Makefile
@@ -1,6 +1,6 @@
 # SPDX-License-Identifier: GPL-2.0
 
-wilco_ec-objs				:= core.o mailbox.o
+wilco_ec-objs				:= core.o mailbox.o properties.o
 obj-$(CONFIG_WILCO_EC)			+= wilco_ec.o
 wilco_ec_debugfs-objs			:= debugfs.o
 obj-$(CONFIG_WILCO_EC_DEBUGFS)		+= wilco_ec_debugfs.o
diff --git a/drivers/platform/chrome/wilco_ec/properties.c b/drivers/platform/chrome/wilco_ec/properties.c
new file mode 100644
index 000000000000..e69682c95ea2
--- /dev/null
+++ b/drivers/platform/chrome/wilco_ec/properties.c
@@ -0,0 +1,132 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright 2019 Google LLC
+ */
+
+#include <linux/platform_data/wilco-ec.h>
+#include <linux/string.h>
+#include <linux/unaligned/le_memmove.h>
+
+/* Operation code; what the EC should do with the property */
+enum ec_property_op {
+	EC_OP_GET = 0,
+	EC_OP_SET = 1,
+};
+
+struct ec_property_request {
+	u8 op; /* One of enum ec_property_op */
+	u8 property_id[4]; /* The 32 bit PID is stored Little Endian */
+	u8 length;
+	u8 data[WILCO_EC_PROPERTY_MAX_SIZE];
+} __packed;
+
+struct ec_property_response {
+	u8 reserved[2];
+	u8 op; /* One of enum ec_property_op */
+	u8 property_id[4]; /* The 32 bit PID is stored Little Endian */
+	u8 length;
+	u8 data[WILCO_EC_PROPERTY_MAX_SIZE];
+} __packed;
+
+static int send_property_msg(struct wilco_ec_device *ec,
+			     struct ec_property_request *rq,
+			     struct ec_property_response *rs)
+{
+	struct wilco_ec_message ec_msg;
+	int ret;
+
+	memset(&ec_msg, 0, sizeof(ec_msg));
+	ec_msg.type = WILCO_EC_MSG_PROPERTY;
+	ec_msg.request_data = rq;
+	ec_msg.request_size = sizeof(*rq);
+	ec_msg.response_data = rs;
+	ec_msg.response_size = sizeof(*rs);
+
+	ret = wilco_ec_mailbox(ec, &ec_msg);
+	if (ret < 0)
+		return ret;
+	if (rs->op != rq->op)
+		return -EBADMSG;
+	if (memcmp(rq->property_id, rs->property_id, sizeof(rs->property_id)))
+		return -EBADMSG;
+
+	return 0;
+}
+
+int wilco_ec_get_property(struct wilco_ec_device *ec,
+			  struct wilco_ec_property_msg *prop_msg)
+{
+	struct ec_property_request rq;
+	struct ec_property_response rs;
+	int ret;
+
+	memset(&rq, 0, sizeof(rq));
+	rq.op = EC_OP_GET;
+	put_unaligned_le32(prop_msg->property_id, rq.property_id);
+
+	ret = send_property_msg(ec, &rq, &rs);
+	if (ret < 0)
+		return ret;
+
+	prop_msg->length = rs.length;
+	memcpy(prop_msg->data, rs.data, rs.length);
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(wilco_ec_get_property);
+
+int wilco_ec_set_property(struct wilco_ec_device *ec,
+			  struct wilco_ec_property_msg *prop_msg)
+{
+	struct ec_property_request rq;
+	struct ec_property_response rs;
+	int ret;
+
+	memset(&rq, 0, sizeof(rq));
+	rq.op = EC_OP_SET;
+	put_unaligned_le32(prop_msg->property_id, rq.property_id);
+	rq.length = prop_msg->length;
+	memcpy(rq.data, prop_msg->data, prop_msg->length);
+
+	ret = send_property_msg(ec, &rq, &rs);
+	if (ret < 0)
+		return ret;
+	if (rs.length != prop_msg->length)
+		return -EBADMSG;
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(wilco_ec_set_property);
+
+int wilco_ec_get_byte_property(struct wilco_ec_device *ec, u32 property_id,
+			       u8 *val)
+{
+	struct wilco_ec_property_msg msg;
+	int ret;
+
+	msg.property_id = property_id;
+
+	ret = wilco_ec_get_property(ec, &msg);
+	if (ret < 0)
+		return ret;
+	if (msg.length != 1)
+		return -EBADMSG;
+
+	*val = msg.data[0];
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(wilco_ec_get_byte_property);
+
+int wilco_ec_set_byte_property(struct wilco_ec_device *ec, u32 property_id,
+			       u8 val)
+{
+	struct wilco_ec_property_msg msg;
+
+	msg.property_id = property_id;
+	msg.data[0] = val;
+	msg.length = 1;
+
+	return wilco_ec_set_property(ec, &msg);
+}
+EXPORT_SYMBOL_GPL(wilco_ec_set_byte_property);