[RFC PATCH 4/8] firmware: arm_scmi: add initial support for performance protocol

[Sudeep Holla]

The performance protocol is intended for the performance management of
group(s) of device(s) that run in the same performance domain. It
includes even the CPUs. A performance domain is defined by a set of
devices that always have to run at the same performance level.
For example, a set of CPUs that share a voltage domain, and have a
common frequency control, is said to be in the same performance domain.

The commands in this protocol provide functionality to describe the
protocol version, describe various attribute flags, set and get the
performance level of a domain. It also supports discovery of the list
of performance levels supported by a performance domain, and the
properties of each performance level.

This patch adds basic support for the performance protocol.

Signed-off-by: Sudeep Holla <sudeep.holla@xxxxxxx>
---
 drivers/firmware/arm_scmi/Makefile |   2 +-
 drivers/firmware/arm_scmi/common.h |   1 +
 drivers/firmware/arm_scmi/perf.c   | 398 +++++++++++++++++++++++++++++++++++++
 include/linux/scmi_protocol.h      |  32 +++
 4 files changed, 432 insertions(+), 1 deletion(-)
 create mode 100644 drivers/firmware/arm_scmi/perf.c

diff --git a/drivers/firmware/arm_scmi/Makefile b/drivers/firmware/arm_scmi/Makefile
index 21d01d1d6b9c..159de726ee45 100644
--- a/drivers/firmware/arm_scmi/Makefile
+++ b/drivers/firmware/arm_scmi/Makefile
@@ -1,2 +1,2 @@
 obj-$(CONFIG_ARM_SCMI_PROTOCOL)	= arm_scmi.o
-arm_scmi-y = base.o driver.o
+arm_scmi-y = base.o driver.o perf.o
diff --git a/drivers/firmware/arm_scmi/common.h b/drivers/firmware/arm_scmi/common.h
index 24bc51dcc6c5..e153f05720e4 100644
--- a/drivers/firmware/arm_scmi/common.h
+++ b/drivers/firmware/arm_scmi/common.h
@@ -30,6 +30,7 @@
 #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
+#define MAX_OPPS		16
 
 enum scmi_std_protocol {
 	SCMI_PROTOCOL_BASE = 0x10,
diff --git a/drivers/firmware/arm_scmi/perf.c b/drivers/firmware/arm_scmi/perf.c
new file mode 100644
index 000000000000..25a21bb5c3ef
--- /dev/null
+++ b/drivers/firmware/arm_scmi/perf.c
@@ -0,0 +1,398 @@
+/*
+ * System Control and Management Interface (SCMI) Performance Protocol
+ *
+ * Copyright (C) 2017 ARM Ltd.
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
+ * more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include "common.h"
+
+enum scmi_performance_protocol_cmd {
+	PERF_DOMAIN_ATTRIBUTES = 0x3,
+	PERF_DESCRIBE_LEVELS = 0x4,
+	PERF_LIMITS_SET = 0x5,
+	PERF_LIMITS_GET = 0x6,
+	PERF_LEVEL_SET = 0x7,
+	PERF_LEVEL_GET = 0x8,
+	PERF_NOTIFY_LIMITS = 0x9,
+	PERF_NOTIFY_LEVEL = 0xa,
+};
+
+struct scmi_msg_resp_perf_attributes {
+	__le16 num_domains;
+	__le16 flags;
+#define POWER_SCALE_IN_MILLIWATT(x)	((x) & BIT(0))
+	__le32 stats_addr_low;
+	__le32 stats_addr_high;
+	__le32 stats_size;
+} __packed;
+
+struct scmi_msg_resp_perf_domain_attributes {
+	__le32 flags;
+#define SUPPORTS_SET_LIMITS(x)		((x) & BIT(31))
+#define SUPPORTS_SET_PERF_LVL(x)	((x) & BIT(30))
+#define SUPPORTS_PERF_LIMIT_NOTIFY(x)	((x) & BIT(29))
+#define SUPPORTS_PERF_LEVEL_NOTIFY(x)	((x) & BIT(28))
+	__le16 rate_limit_us;
+	__le16 reserved3;
+	__le32 max_freq;
+	__le32 min_freq;
+#define FREQUENCY_BASE(x)		((x) >> 16)
+#define FREQUENCY_SCALE(x)		((x) & 0x3f)
+	    u8 name[SCMI_MAX_STR_SIZE];
+} __packed;
+
+struct scmi_msg_perf_describe_levels {
+	__le32 domain;
+	__le32 level_index;
+} __packed;
+
+struct scmi_perf_set_limits {
+	__le32 domain;
+	__le32 max_level;
+	__le32 min_level;
+} __packed;
+
+struct scmi_perf_get_limits {
+	__le32 max_level;
+	__le32 min_level;
+} __packed;
+
+struct scmi_perf_set_level {
+	__le32 domain;
+	__le32 level;
+} __packed;
+
+struct scmi_perf_notify_level_or_limits {
+	__le32 domain;
+	__le32 notify_enable;
+} __packed;
+
+struct scmi_msg_resp_perf_describe_levels {
+	__le16 num_returned;
+	__le16 num_remaining;
+	struct {
+		__le32 perf_val;
+		__le32 power;
+		__le16 transition_latency_us;
+		__le16 reserved;
+	} opp[0];
+} __packed;
+
+struct perf_dom_info {
+	bool set_limits;
+	bool set_perf;
+	bool perf_limit_notify;
+	bool perf_level_notify;
+	char name[SCMI_MAX_STR_SIZE];
+	struct scmi_opp opp[MAX_OPPS];
+};
+
+struct scmi_perf_info {
+	int num_domains;
+	bool power_scale_mw;
+	u64 stats_addr;
+	u32 stats_size;
+	struct perf_dom_info *dom_info;
+};
+
+static struct scmi_perf_info perf_info;
+
+static int scmi_perf_attributes_get(struct scmi_handle *handle,
+				    struct scmi_perf_info *perf_info)
+{
+	int ret;
+	struct scmi_xfer *t;
+	struct scmi_msg_resp_perf_attributes *attr;
+
+	ret = scmi_one_xfer_init(handle, PROTOCOL_ATTRIBUTES,
+				 SCMI_PROTOCOL_PERF, 0, sizeof(*attr), &t);
+	if (ret)
+		return ret;
+
+	attr = (struct scmi_msg_resp_perf_attributes *)t->rx.buf;
+
+	ret = scmi_do_xfer(handle, t);
+	if (!ret) {
+		u16 flags = le16_to_cpu(attr->flags);
+
+		perf_info->num_domains = le16_to_cpu(attr->num_domains);
+		perf_info->power_scale_mw = POWER_SCALE_IN_MILLIWATT(flags);
+		perf_info->stats_addr = le32_to_cpu(attr->stats_addr_low) |
+				(u64)le32_to_cpu(attr->stats_addr_high) << 32;
+		perf_info->stats_size = le32_to_cpu(attr->stats_size);
+	}
+
+	scmi_put_one_xfer(handle, t);
+	return ret;
+}
+
+static int
+scmi_perf_domain_attributes_get(struct scmi_handle *handle, u32 domain,
+				struct perf_dom_info *dom_info)
+{
+	int ret;
+	struct scmi_xfer *t;
+	struct scmi_msg_resp_perf_domain_attributes *attr;
+
+	ret = scmi_one_xfer_init(handle, PERF_DOMAIN_ATTRIBUTES,
+				 SCMI_PROTOCOL_PERF, sizeof(domain),
+				 sizeof(*attr), &t);
+	if (ret)
+		return ret;
+
+	*(__le32 *)t->tx.buf = cpu_to_le32(domain);
+	attr = (struct scmi_msg_resp_perf_domain_attributes *)t->rx.buf;
+
+	ret = scmi_do_xfer(handle, t);
+	if (!ret) {
+		u32 flags = le32_to_cpu(attr->flags);
+
+		dom_info->set_limits = SUPPORTS_SET_LIMITS(flags);
+		dom_info->set_perf = SUPPORTS_SET_PERF_LVL(flags);
+		dom_info->perf_limit_notify = SUPPORTS_PERF_LIMIT_NOTIFY(flags);
+		dom_info->perf_level_notify = SUPPORTS_PERF_LEVEL_NOTIFY(flags);
+		memcpy(dom_info->name, attr->name, SCMI_MAX_STR_SIZE);
+	}
+
+	scmi_put_one_xfer(handle, t);
+	return ret;
+}
+
+static int scmi_perf_describe_levels_get(struct scmi_handle *handle, u32 domain,
+					 struct perf_dom_info *perf_dom)
+{
+	int ret, cnt;
+	u32 tot_opp_cnt = 0;
+	u16 num_returned, num_remaining;
+	struct scmi_xfer *t;
+	struct scmi_opp *opp;
+	struct scmi_msg_perf_describe_levels *dom_info;
+	struct scmi_msg_resp_perf_describe_levels *level_info;
+
+	ret = scmi_one_xfer_init(handle, PERF_DESCRIBE_LEVELS,
+				 SCMI_PROTOCOL_PERF, sizeof(*dom_info), 0, &t);
+	if (ret)
+		return ret;
+
+	dom_info = (struct scmi_msg_perf_describe_levels *)t->tx.buf;
+	level_info = (struct scmi_msg_resp_perf_describe_levels *)t->rx.buf;
+
+	do {
+		dom_info->domain = cpu_to_le32(domain);
+		/* Set the number of OPPs to be skipped/already read */
+		dom_info->level_index = cpu_to_le32(tot_opp_cnt);
+
+		ret = scmi_do_xfer(handle, t);
+		if (ret)
+			break;
+
+		num_returned = le16_to_cpu(level_info->num_returned);
+		num_remaining = le16_to_cpu(level_info->num_remaining);
+		if (tot_opp_cnt + num_returned > MAX_OPPS) {
+			dev_err(handle->dev, "No. of OPPs exceeded MAX_OPPS");
+			break;
+		}
+
+		opp = &perf_dom->opp[tot_opp_cnt];
+		for (cnt = 0; cnt < num_returned; cnt++, opp++) {
+			opp->freq = le32_to_cpu(level_info->opp[cnt].perf_val);
+			opp->volt = le32_to_cpu(level_info->opp[cnt].power);
+			opp->trans_latency_us = le16_to_cpu(
+				level_info->opp[cnt].transition_latency_us);
+
+			dev_dbg(handle->dev, "Level %d Power %d Latency %dus\n",
+				opp->freq, opp->volt, opp->trans_latency_us);
+		}
+
+		tot_opp_cnt += num_returned;
+		/*
+		 * check for both returned and remaining to avoid infinite
+		 * loop due to buggy firmware
+		 */
+	} while (num_returned && num_remaining);
+
+	scmi_put_one_xfer(handle, t);
+	return ret;
+}
+
+static int scmi_perf_limits_set(struct scmi_handle *handle, u32 domain,
+				u32 max_perf, u32 min_perf)
+{
+	int ret;
+	struct scmi_xfer *t;
+	struct scmi_perf_set_limits *limits;
+
+	ret = scmi_one_xfer_init(handle, PERF_LIMITS_SET, SCMI_PROTOCOL_PERF,
+				 sizeof(*limits), 0, &t);
+	if (ret)
+		return ret;
+
+	limits = (struct scmi_perf_set_limits *)t->tx.buf;
+	limits->domain = cpu_to_le32(domain);
+	limits->max_level = cpu_to_le32(max_perf);
+	limits->min_level = cpu_to_le32(min_perf);
+
+	ret = scmi_do_xfer(handle, t);
+
+	scmi_put_one_xfer(handle, t);
+	return ret;
+}
+
+static int scmi_perf_limits_get(struct scmi_handle *handle, u32 domain,
+				u32 *max_perf, u32 *min_perf)
+{
+	int ret;
+	struct scmi_xfer *t;
+	struct scmi_perf_get_limits *limits;
+
+	ret = scmi_one_xfer_init(handle, PERF_LIMITS_GET, SCMI_PROTOCOL_PERF,
+				 sizeof(__le32), 0, &t);
+	if (ret)
+		return ret;
+
+	*(__le32 *)t->tx.buf = cpu_to_le32(domain);
+
+	ret = scmi_do_xfer(handle, t);
+	if (!ret) {
+		limits = (struct scmi_perf_get_limits *)t->rx.buf;
+
+		*max_perf = le32_to_cpu(limits->max_level);
+		*min_perf = le32_to_cpu(limits->min_level);
+	}
+
+	scmi_put_one_xfer(handle, t);
+	return ret;
+}
+
+static int
+scmi_perf_level_set(struct scmi_handle *handle, u32 domain, u32 level)
+{
+	int ret;
+	struct scmi_xfer *t;
+	struct scmi_perf_set_level *lvl;
+
+	ret = scmi_one_xfer_init(handle, PERF_LEVEL_SET, SCMI_PROTOCOL_PERF,
+				 sizeof(*lvl), 0, &t);
+	if (ret)
+		return ret;
+
+	lvl = (struct scmi_perf_set_level *)t->tx.buf;
+	lvl->domain = cpu_to_le32(domain);
+	lvl->level = cpu_to_le32(level);
+
+	ret = scmi_do_xfer(handle, t);
+
+	scmi_put_one_xfer(handle, t);
+	return ret;
+}
+
+static int
+scmi_perf_level_get(struct scmi_handle *handle, u32 domain, u32 *level)
+{
+	int ret;
+	struct scmi_xfer *t;
+
+	ret = scmi_one_xfer_init(handle, PERF_LEVEL_GET, SCMI_PROTOCOL_PERF,
+				 sizeof(u32), sizeof(u32), &t);
+	if (ret)
+		return ret;
+
+	*(__le32 *)t->tx.buf = cpu_to_le32(domain);
+
+	ret = scmi_do_xfer(handle, t);
+	if (!ret)
+		*level = le32_to_cpu(*(__le32 *)t->rx.buf);
+
+	scmi_put_one_xfer(handle, t);
+	return ret;
+}
+
+static int __scmi_perf_notify_enable(struct scmi_handle *handle, u32 cmd,
+				     u32 domain, bool enable)
+{
+	int ret;
+	struct scmi_xfer *t;
+	struct scmi_perf_notify_level_or_limits *notify;
+
+	ret = scmi_one_xfer_init(handle, cmd, SCMI_PROTOCOL_PERF,
+				 sizeof(*notify), 0, &t);
+	if (ret)
+		return ret;
+
+	notify = (struct scmi_perf_notify_level_or_limits *)t->tx.buf;
+	notify->domain = cpu_to_le32(domain);
+	notify->notify_enable = cpu_to_le32(enable & BIT(0));
+
+	ret = scmi_do_xfer(handle, t);
+
+	scmi_put_one_xfer(handle, t);
+	return ret;
+}
+
+static int
+scmi_perf_limits_notify_enable(struct scmi_handle *handle, u32 dom, bool en)
+{
+	return __scmi_perf_notify_enable(handle, PERF_NOTIFY_LIMITS, dom, en);
+}
+
+static int
+scmi_perf_level_notify_enable(struct scmi_handle *handle, u32 dom, bool en)
+{
+	return __scmi_perf_notify_enable(handle, PERF_NOTIFY_LEVEL, dom, en);
+}
+
+static struct scmi_perf_ops perf_ops = {
+	.limits_set = scmi_perf_limits_set,
+	.limits_get = scmi_perf_limits_get,
+	.level_set = scmi_perf_level_set,
+	.level_get = scmi_perf_level_get,
+	.limits_notify_enable = scmi_perf_limits_notify_enable,
+	.level_notify_enable = scmi_perf_level_notify_enable,
+};
+
+int scmi_perf_protocol_init(struct scmi_handle *handle)
+{
+	int domain;
+	u32 version;
+
+	if (!scmi_is_protocol_implemented(handle, SCMI_PROTOCOL_PERF)) {
+		dev_err(handle->dev, "SCMI Perf protocol not implemented\n");
+		return -EPROTONOSUPPORT;
+	}
+
+	scmi_version_get(handle, SCMI_PROTOCOL_PERF, &version);
+
+	dev_dbg(handle->dev, "Performance Version %d.%d\n",
+		PROTOCOL_REV_MAJOR(version), PROTOCOL_REV_MINOR(version));
+
+	scmi_perf_attributes_get(handle, &perf_info);
+
+	perf_info.dom_info = devm_kcalloc(handle->dev, perf_info.num_domains,
+					     sizeof(struct perf_dom_info),
+					     GFP_KERNEL);
+	if (!perf_info.dom_info)
+		return -ENOMEM;
+
+	for (domain = 0; domain < perf_info.num_domains; domain++) {
+		struct perf_dom_info *dom = perf_info.dom_info + domain;
+
+		scmi_perf_domain_attributes_get(handle, domain, dom);
+		scmi_perf_describe_levels_get(handle, domain, dom);
+	}
+
+	handle->perf_ops = &perf_ops;
+
+	return 0;
+}
diff --git a/include/linux/scmi_protocol.h b/include/linux/scmi_protocol.h
index 901976fe211f..0f25a3defb4c 100644
--- a/include/linux/scmi_protocol.h
+++ b/include/linux/scmi_protocol.h
@@ -43,15 +43,47 @@ struct scmi_revision_info {
 	char sub_vendor_id[SCMI_MAX_STR_SIZE];
 };
 
+struct scmi_handle;
+
+/**
+ * struct scmi_perf_ops - represents the various operations provided
+ *	by SCMI Performance Protocol
+ *
+ * @limits_set: sets limits on the performance level of a domain
+ * @limits_get: gets limits on the performance level of a domain
+ * @level_set: sets the performance level of a domain
+ * @level_get: gets the performance level of a domain
+ * @limits_notify_enable: requests notifications from the platform for changes
+ *	in the allowed maximum and minimum performance levels
+ * @level_notify_enable: requests notifications from the platform when the
+ *	performance level for a domain changes in value
+ */
+struct scmi_perf_ops {
+	int (*limits_set)(struct scmi_handle *, u32, u32, u32);
+	int (*limits_get)(struct scmi_handle *, u32, u32 *, u32 *);
+	int (*level_set)(struct scmi_handle *, u32, u32 level);
+	int (*level_get)(struct scmi_handle *, u32, u32 *);
+	int (*limits_notify_enable)(struct scmi_handle *, u32, bool);
+	int (*level_notify_enable)(struct scmi_handle *, u32, bool);
+};
+
 /**
  * struct scmi_handle - Handle returned to ARM SCMI clients for usage.
  *
  * @dev: pointer to the SCMI device
  * @version: pointer to the structure containing SCMI version information
+ * @perf_ops: pointer to set of performance protocol operations
  */
 struct scmi_handle {
 	struct device *dev;
 	struct scmi_revision_info *version;
+	struct scmi_perf_ops *perf_ops;
+};
+
+struct scmi_opp {
+	u32 freq;
+	u32 volt;
+	u32 trans_latency_us;
 };
 
 #if IS_REACHABLE(CONFIG_ARM_SCMI_PROTOCOL)
-- 
2.7.4