firmware: arm_scmi: add common infrastructure and support for base pr…

…otocol

The base protocol describes the properties of the implementation and
provide generic error management. The base protocol provides commands
to describe protocol version, discover implementation specific
attributes and vendor/sub-vendor identification, list of protocols
implemented and the various agents are in the system including OSPM
and the platform. It also supports registering for notifications of
platform errors.

This protocol is mandatory. This patch adds support for the same along
with some basic infrastructure to add support for other protocols.

Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

drivers/firmware/arm_scmi/Makefile

@@ -1,2 +1,3 @@
-obj-y	= scmi-driver.o
+obj-y	= scmi-driver.o scmi-protocols.o
 scmi-driver-y = driver.o
+scmi-protocols-y = base.o

drivers/firmware/arm_scmi/base.c

@@ -0,0 +1,253 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * System Control and Management Interface (SCMI) Base Protocol
+ *
+ * Copyright (C) 2018 ARM Ltd.
+ */
+
+#include "common.h"
+
+enum scmi_base_protocol_cmd {
+	BASE_DISCOVER_VENDOR = 0x3,
+	BASE_DISCOVER_SUB_VENDOR = 0x4,
+	BASE_DISCOVER_IMPLEMENT_VERSION = 0x5,
+	BASE_DISCOVER_LIST_PROTOCOLS = 0x6,
+	BASE_DISCOVER_AGENT = 0x7,
+	BASE_NOTIFY_ERRORS = 0x8,
+};
+
+struct scmi_msg_resp_base_attributes {
+	u8 num_protocols;
+	u8 num_agents;
+	__le16 reserved;
+};
+
+/**
+ * scmi_base_attributes_get() - gets the implementation details
+ *	that are associated with the base protocol.
+ *
+ * @handle - SCMI entity handle
+ *
+ * Return: 0 on success, else appropriate SCMI error.
+ */
+static int scmi_base_attributes_get(const struct scmi_handle *handle)
+{
+	int ret;
+	struct scmi_xfer *t;
+	struct scmi_msg_resp_base_attributes *attr_info;
+	struct scmi_revision_info *rev = handle->version;
+
+	ret = scmi_one_xfer_init(handle, PROTOCOL_ATTRIBUTES,
+				 SCMI_PROTOCOL_BASE, 0, sizeof(*attr_info), &t);
+	if (ret)
+		return ret;
+
+	ret = scmi_do_xfer(handle, t);
+	if (!ret) {
+		attr_info = t->rx.buf;
+		rev->num_protocols = attr_info->num_protocols;
+		rev->num_agents = attr_info->num_agents;
+	}
+
+	scmi_one_xfer_put(handle, t);
+	return ret;
+}
+
+/**
+ * scmi_base_vendor_id_get() - gets vendor/subvendor identifier ASCII string.
+ *
+ * @handle - SCMI entity handle
+ * @sub_vendor - specify true if sub-vendor ID is needed
+ *
+ * Return: 0 on success, else appropriate SCMI error.
+ */
+static int
+scmi_base_vendor_id_get(const struct scmi_handle *handle, bool sub_vendor)
+{
+	u8 cmd;
+	int ret, size;
+	char *vendor_id;
+	struct scmi_xfer *t;
+	struct scmi_revision_info *rev = handle->version;
+
+	if (sub_vendor) {
+		cmd = BASE_DISCOVER_SUB_VENDOR;
+		vendor_id = rev->sub_vendor_id;
+		size = ARRAY_SIZE(rev->sub_vendor_id);
+	} else {
+		cmd = BASE_DISCOVER_VENDOR;
+		vendor_id = rev->vendor_id;
+		size = ARRAY_SIZE(rev->vendor_id);
+	}
+
+	ret = scmi_one_xfer_init(handle, cmd, SCMI_PROTOCOL_BASE, 0, size, &t);
+	if (ret)
+		return ret;
+
+	ret = scmi_do_xfer(handle, t);
+	if (!ret)
+		memcpy(vendor_id, t->rx.buf, size);
+
+	scmi_one_xfer_put(handle, t);
+	return ret;
+}
+
+/**
+ * scmi_base_implementation_version_get() - gets a vendor-specific
+ *	implementation 32-bit version. The format of the version number is
+ *	vendor-specific
+ *
+ * @handle - SCMI entity handle
+ *
+ * Return: 0 on success, else appropriate SCMI error.
+ */
+static int
+scmi_base_implementation_version_get(const struct scmi_handle *handle)
+{
+	int ret;
+	__le32 *impl_ver;
+	struct scmi_xfer *t;
+	struct scmi_revision_info *rev = handle->version;
+
+	ret = scmi_one_xfer_init(handle, BASE_DISCOVER_IMPLEMENT_VERSION,
+				 SCMI_PROTOCOL_BASE, 0, sizeof(*impl_ver), &t);
+	if (ret)
+		return ret;
+
+	ret = scmi_do_xfer(handle, t);
+	if (!ret) {
+		impl_ver = t->rx.buf;
+		rev->impl_ver = le32_to_cpu(*impl_ver);
+	}
+
+	scmi_one_xfer_put(handle, t);
+	return ret;
+}
+
+/**
+ * scmi_base_implementation_list_get() - gets the list of protocols it is
+ *	OSPM is allowed to access
+ *
+ * @handle - SCMI entity handle
+ * @protocols_imp - pointer to hold the list of protocol identifiers
+ *
+ * Return: 0 on success, else appropriate SCMI error.
+ */
+static int scmi_base_implementation_list_get(const struct scmi_handle *handle,
+					     u8 *protocols_imp)
+{
+	u8 *list;
+	int ret, loop;
+	struct scmi_xfer *t;
+	__le32 *num_skip, *num_ret;
+	u32 tot_num_ret = 0, loop_num_ret;
+	struct device *dev = handle->dev;
+
+	ret = scmi_one_xfer_init(handle, BASE_DISCOVER_LIST_PROTOCOLS,
+				 SCMI_PROTOCOL_BASE, sizeof(*num_skip), 0, &t);
+	if (ret)
+		return ret;
+
+	num_skip = t->tx.buf;
+	num_ret = t->rx.buf;
+	list = t->rx.buf + sizeof(*num_ret);
+
+	do {
+		/* Set the number of protocols to be skipped/already read */
+		*num_skip = cpu_to_le32(tot_num_ret);
+
+		ret = scmi_do_xfer(handle, t);
+		if (ret)
+			break;
+
+		loop_num_ret = le32_to_cpu(*num_ret);
+		if (tot_num_ret + loop_num_ret > MAX_PROTOCOLS_IMP) {
+			dev_err(dev, "No. of Protocol > MAX_PROTOCOLS_IMP");
+			break;
+		}
+
+		for (loop = 0; loop < loop_num_ret; loop++)
+			protocols_imp[tot_num_ret + loop] = *(list + loop);
+
+		tot_num_ret += loop_num_ret;
+	} while (loop_num_ret);
+
+	scmi_one_xfer_put(handle, t);
+	return ret;
+}
+
+/**
+ * scmi_base_discover_agent_get() - discover the name of an agent
+ *
+ * @handle - SCMI entity handle
+ * @id - Agent identifier
+ * @name - Agent identifier ASCII string
+ *
+ * An agent id of 0 is reserved to identify the platform itself.
+ * Generally operating system is represented as "OSPM"
+ *
+ * Return: 0 on success, else appropriate SCMI error.
+ */
+static int scmi_base_discover_agent_get(const struct scmi_handle *handle,
+					int id, char *name)
+{
+	int ret;
+	struct scmi_xfer *t;
+
+	ret = scmi_one_xfer_init(handle, BASE_DISCOVER_AGENT,
+				 SCMI_PROTOCOL_BASE, sizeof(__le32),
+				 SCMI_MAX_STR_SIZE, &t);
+	if (ret)
+		return ret;
+
+	*(__le32 *)t->tx.buf = cpu_to_le32(id);
+
+	ret = scmi_do_xfer(handle, t);
+	if (!ret)
+		memcpy(name, t->rx.buf, SCMI_MAX_STR_SIZE);
+
+	scmi_one_xfer_put(handle, t);
+	return ret;
+}
+
+int scmi_base_protocol_init(struct scmi_handle *h)
+{
+	int id, ret;
+	u8 *prot_imp;
+	u32 version;
+	char name[SCMI_MAX_STR_SIZE];
+	const struct scmi_handle *handle = h;
+	struct device *dev = handle->dev;
+	struct scmi_revision_info *rev = handle->version;
+
+	ret = scmi_version_get(handle, SCMI_PROTOCOL_BASE, &version);
+	if (ret)
+		return ret;
+
+	prot_imp = devm_kcalloc(dev, MAX_PROTOCOLS_IMP, sizeof(u8), GFP_KERNEL);
+	if (!prot_imp)
+		return -ENOMEM;
+
+	rev->major_ver = PROTOCOL_REV_MAJOR(version),
+	rev->minor_ver = PROTOCOL_REV_MINOR(version);
+
+	scmi_base_attributes_get(handle);
+	scmi_base_vendor_id_get(handle, false);
+	scmi_base_vendor_id_get(handle, true);
+	scmi_base_implementation_version_get(handle);
+	scmi_base_implementation_list_get(handle, prot_imp);
+	scmi_setup_protocol_implemented(handle, prot_imp);
+
+	dev_info(dev, "SCMI Protocol v%d.%d '%s:%s' Firmware version 0x%x\n",
+		 rev->major_ver, rev->minor_ver, rev->vendor_id,
+		 rev->sub_vendor_id, rev->impl_ver);
+	dev_dbg(dev, "Found %d protocol(s) %d agent(s)\n", rev->num_protocols,
+		rev->num_agents);
+
+	for (id = 0; id < rev->num_agents; id++) {
+		scmi_base_discover_agent_get(handle, id, name);
+		dev_dbg(dev, "Agent %d: %s\n", id, name);
+	}
+
+	return 0;
+}

drivers/firmware/arm_scmi/common.h

@@ -8,9 +8,41 @@
  */
 
 #include <linux/completion.h>
+#include <linux/device.h>
+#include <linux/errno.h>
+#include <linux/kernel.h>
 #include <linux/scmi_protocol.h>
 #include <linux/types.h>
 
+#define PROTOCOL_REV_MINOR_BITS	16
+#define PROTOCOL_REV_MINOR_MASK	((1U << PROTOCOL_REV_MINOR_BITS) - 1)
+#define PROTOCOL_REV_MAJOR(x)	((x) >> PROTOCOL_REV_MINOR_BITS)
+#define PROTOCOL_REV_MINOR(x)	((x) & PROTOCOL_REV_MINOR_MASK)
+#define MAX_PROTOCOLS_IMP	16
+
+enum scmi_common_cmd {
+	PROTOCOL_VERSION = 0x0,
+	PROTOCOL_ATTRIBUTES = 0x1,
+	PROTOCOL_MESSAGE_ATTRIBUTES = 0x2,
+};
+
+/**
+ * struct scmi_msg_resp_prot_version - Response for a message
+ *
+ * @major_version: Major version of the ABI that firmware supports
+ * @minor_version: Minor version of the ABI that firmware supports
+ *
+ * In general, ABI version changes follow the rule that minor version increments
+ * are backward compatible. Major revision changes in ABI may not be
+ * backward compatible.
+ *
+ * Response to a generic message with message type SCMI_MSG_VERSION
+ */
+struct scmi_msg_resp_prot_version {
+	__le16 minor_version;
+	__le16 major_version;
+};
+
 /**
  * struct scmi_msg_hdr - Message(Tx/Rx) header
  *
@@ -64,3 +96,8 @@ int scmi_one_xfer_init(const struct scmi_handle *h, u8 msg_id, u8 prot_id,
 		       size_t tx_size, size_t rx_size, struct scmi_xfer **p);
 int scmi_handle_put(const struct scmi_handle *handle);
 struct scmi_handle *scmi_handle_get(struct device *dev);
+int scmi_version_get(const struct scmi_handle *h, u8 protocol, u32 *version);
+void scmi_setup_protocol_implemented(const struct scmi_handle *handle,
+				     u8 *prot_imp);
+
+int scmi_base_protocol_init(struct scmi_handle *h);