firmware: arm_scmi: Add discovery of SCMI v2.0 performance fastchannels

SCMI v2.0 adds support for "FastChannel", a lightweight unidirectional
channel that is dedicated to a single SCMI message type for controlling
a specific platform resource. They do not use a message header as they
are specialized for a single message.

Only PERFORMANCE_LIMITS_{SET,GET} and PERFORMANCE_LEVEL_{SET,GET}
commands are supported over fastchannels. As they are optional, they
need to be discovered by PERFORMANCE_DESCRIBE_FASTCHANNEL command.
Further {LIMIT,LEVEL}_SET commands can have optional doorbell support.

Add support for discovery of these fastchannels.

Cc: Ionela Voinescu <Ionela.Voinescu@arm.com>
Cc: Chris Redpath <Chris.Redpath@arm.com>
Cc: Quentin Perret <Quentin.Perret@arm.com>
Reviewed-by: Peng Fan <peng.fan@nxp.com>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

drivers/firmware/arm_scmi/perf.c

@@ -5,7 +5,9 @@
  * Copyright (C) 2018 ARM Ltd.
  */
 
+#include <linux/bits.h>
 #include <linux/of.h>
+#include <linux/io.h>
 #include <linux/platform_device.h>
 #include <linux/pm_opp.h>
 #include <linux/sort.h>
@@ -21,6 +23,7 @@ enum scmi_performance_protocol_cmd {
 	PERF_LEVEL_GET = 0x8,
 	PERF_NOTIFY_LIMITS = 0x9,
 	PERF_NOTIFY_LEVEL = 0xa,
+	PERF_DESCRIBE_FASTCHANNEL = 0xb,
 };
 
 struct scmi_opp {
@@ -44,6 +47,7 @@ struct scmi_msg_resp_perf_domain_attributes {
 #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))
+#define SUPPORTS_PERF_FASTCHANNELS(x)	((x) & BIT(27))
 	__le32 rate_limit_us;
 	__le32 sustained_freq_khz;
 	__le32 sustained_perf_level;
@@ -87,17 +91,56 @@ struct scmi_msg_resp_perf_describe_levels {
 	} opp[0];
 };
 
+struct scmi_perf_get_fc_info {
+	__le32 domain;
+	__le32 message_id;
+};
+
+struct scmi_msg_resp_perf_desc_fc {
+	__le32 attr;
+#define SUPPORTS_DOORBELL(x)		((x) & BIT(0))
+#define DOORBELL_REG_WIDTH(x)		FIELD_GET(GENMASK(2, 1), (x))
+	__le32 rate_limit;
+	__le32 chan_addr_low;
+	__le32 chan_addr_high;
+	__le32 chan_size;
+	__le32 db_addr_low;
+	__le32 db_addr_high;
+	__le32 db_set_lmask;
+	__le32 db_set_hmask;
+	__le32 db_preserve_lmask;
+	__le32 db_preserve_hmask;
+};
+
+struct scmi_fc_db_info {
+	int width;
+	u64 set;
+	u64 mask;
+	void __iomem *addr;
+};
+
+struct scmi_fc_info {
+	void __iomem *level_set_addr;
+	void __iomem *limit_set_addr;
+	void __iomem *level_get_addr;
+	void __iomem *limit_get_addr;
+	struct scmi_fc_db_info *level_set_db;
+	struct scmi_fc_db_info *limit_set_db;
+};
+
 struct perf_dom_info {
 	bool set_limits;
 	bool set_perf;
 	bool perf_limit_notify;
 	bool perf_level_notify;
+	bool perf_fastchannels;
 	u32 opp_count;
 	u32 sustained_freq_khz;
 	u32 sustained_perf_level;
 	u32 mult_factor;
 	char name[SCMI_MAX_STR_SIZE];
 	struct scmi_opp opp[MAX_OPPS];
+	struct scmi_fc_info *fc_info;
 };
 
 struct scmi_perf_info {
@@ -162,6 +205,7 @@ scmi_perf_domain_attributes_get(const struct scmi_handle *handle, u32 domain,
 		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);
+		dom_info->perf_fastchannels = SUPPORTS_PERF_FASTCHANNELS(flags);
 		dom_info->sustained_freq_khz =
 					le32_to_cpu(attr->sustained_freq_khz);
 		dom_info->sustained_perf_level =
@@ -343,6 +387,104 @@ static int scmi_perf_level_get(const struct scmi_handle *handle, u32 domain,
 	return ret;
 }
 
+static bool scmi_perf_fc_size_is_valid(u32 msg, u32 size)
+{
+	if ((msg == PERF_LEVEL_GET || msg == PERF_LEVEL_SET) && size == 4)
+		return true;
+	if ((msg == PERF_LIMITS_GET || msg == PERF_LIMITS_SET) && size == 8)
+		return true;
+	return false;
+}
+
+static void
+scmi_perf_domain_desc_fc(const struct scmi_handle *handle, u32 domain,
+			 u32 message_id, void __iomem **p_addr,
+			 struct scmi_fc_db_info **p_db)
+{
+	int ret;
+	u32 flags;
+	u64 phys_addr;
+	u8 size;
+	void __iomem *addr;
+	struct scmi_xfer *t;
+	struct scmi_fc_db_info *db;
+	struct scmi_perf_get_fc_info *info;
+	struct scmi_msg_resp_perf_desc_fc *resp;
+
+	if (!p_addr)
+		return;
+
+	ret = scmi_xfer_get_init(handle, PERF_DESCRIBE_FASTCHANNEL,
+				 SCMI_PROTOCOL_PERF,
+				 sizeof(*info), sizeof(*resp), &t);
+	if (ret)
+		return;
+
+	info = t->tx.buf;
+	info->domain = cpu_to_le32(domain);
+	info->message_id = cpu_to_le32(message_id);
+
+	ret = scmi_do_xfer(handle, t);
+	if (ret)
+		goto err_xfer;
+
+	resp = t->rx.buf;
+	flags = le32_to_cpu(resp->attr);
+	size = le32_to_cpu(resp->chan_size);
+	if (!scmi_perf_fc_size_is_valid(message_id, size))
+		goto err_xfer;
+
+	phys_addr = le32_to_cpu(resp->chan_addr_low);
+	phys_addr |= (u64)le32_to_cpu(resp->chan_addr_high) << 32;
+	addr = devm_ioremap(handle->dev, phys_addr, size);
+	if (!addr)
+		goto err_xfer;
+	*p_addr = addr;
+
+	if (p_db && SUPPORTS_DOORBELL(flags)) {
+		db = devm_kzalloc(handle->dev, sizeof(*db), GFP_KERNEL);
+		if (!db)
+			goto err_xfer;
+
+		size = 1 << DOORBELL_REG_WIDTH(flags);
+		phys_addr = le32_to_cpu(resp->db_addr_low);
+		phys_addr |= (u64)le32_to_cpu(resp->db_addr_high) << 32;
+		addr = devm_ioremap(handle->dev, phys_addr, size);
+		if (!addr)
+			goto err_xfer;
+
+		db->addr = addr;
+		db->width = size;
+		db->set = le32_to_cpu(resp->db_set_lmask);
+		db->set |= (u64)le32_to_cpu(resp->db_set_hmask) << 32;
+		db->mask = le32_to_cpu(resp->db_preserve_lmask);
+		db->mask |= (u64)le32_to_cpu(resp->db_preserve_hmask) << 32;
+		*p_db = db;
+	}
+err_xfer:
+	scmi_xfer_put(handle, t);
+}
+
+static void scmi_perf_domain_init_fc(const struct scmi_handle *handle,
+				     u32 domain, struct scmi_fc_info **p_fc)
+{
+	struct scmi_fc_info *fc;
+
+	fc = devm_kzalloc(handle->dev, sizeof(*fc), GFP_KERNEL);
+	if (!fc)
+		return;
+
+	scmi_perf_domain_desc_fc(handle, domain, PERF_LEVEL_SET,
+				 &fc->level_set_addr, &fc->level_set_db);
+	scmi_perf_domain_desc_fc(handle, domain, PERF_LEVEL_GET,
+				 &fc->level_get_addr, NULL);
+	scmi_perf_domain_desc_fc(handle, domain, PERF_LIMITS_SET,
+				 &fc->limit_set_addr, &fc->limit_set_db);
+	scmi_perf_domain_desc_fc(handle, domain, PERF_LIMITS_GET,
+				 &fc->limit_get_addr, NULL);
+	*p_fc = fc;
+}
+
 /* Device specific ops */
 static int scmi_dev_domain_id(struct device *dev)
 {
@@ -494,6 +636,9 @@ static int scmi_perf_protocol_init(struct scmi_handle *handle)
 
 		scmi_perf_domain_attributes_get(handle, domain, dom);
 		scmi_perf_describe_levels_get(handle, domain, dom);
+
+		if (dom->perf_fastchannels)
+			scmi_perf_domain_init_fc(handle, domain, &dom->fc_info);
 	}
 
 	handle->perf_ops = &perf_ops;