[RFC PATCH 1/4] cxl: Register devices for CXL Hotness Monitoring Units (CHMU)

[Jonathan Cameron <Jonathan.Cameron@huawei.com>]

Basic registration using similar approach to how the CPMUs
are registered.

Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
---
 drivers/cxl/core/Makefile |  1 +
 drivers/cxl/core/hmu.c    | 64 +++++++++++++++++++++++++++++++++++++++
 drivers/cxl/core/regs.c   | 14 +++++++++
 drivers/cxl/cxl.h         |  4 +++
 drivers/cxl/cxlpci.h      |  1 +
 drivers/cxl/hmu.h         | 23 ++++++++++++++
 drivers/cxl/pci.c         | 26 +++++++++++++++-
 7 files changed, 132 insertions(+), 1 deletion(-)

diff --git a/drivers/cxl/core/Makefile b/drivers/cxl/core/Makefile
index 9259bcc6773c..d060abb773ae 100644
--- a/drivers/cxl/core/Makefile
+++ b/drivers/cxl/core/Makefile
@@ -12,6 +12,7 @@ cxl_core-y += memdev.o
 cxl_core-y += mbox.o
 cxl_core-y += pci.o
 cxl_core-y += hdm.o
+cxl_core-y += hmu.o
 cxl_core-y += pmu.o
 cxl_core-y += cdat.o
 cxl_core-$(CONFIG_TRACING) += trace.o
diff --git a/drivers/cxl/core/hmu.c b/drivers/cxl/core/hmu.c
new file mode 100644
index 000000000000..3ee938bb6c05
--- /dev/null
+++ b/drivers/cxl/core/hmu.c
@@ -0,0 +1,64 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/* Copyright(c) 2024 Huawei. All rights reserved. */
+
+#include <linux/device.h>
+#include <linux/slab.h>
+#include <linux/idr.h>
+#include <cxlmem.h>
+#include <hmu.h>
+#include <cxl.h>
+#include "core.h"
+
+static void cxl_hmu_release(struct device *dev)
+{
+	struct cxl_hmu *hmu = to_cxl_hmu(dev);
+
+	kfree(hmu);
+}
+
+const struct device_type cxl_hmu_type = {
+	.name = "cxl_hmu",
+	.release = cxl_hmu_release,
+};
+
+static void remove_dev(void *dev)
+{
+	device_unregister(dev);
+}
+
+int devm_cxl_hmu_add(struct device *parent, struct cxl_hmu_regs *regs,
+		     int assoc_id, int index)
+{
+	struct cxl_hmu *hmu;
+	struct device *dev;
+	int rc;
+
+	hmu = kzalloc(sizeof(*hmu), GFP_KERNEL);
+	if (!hmu)
+		return -ENOMEM;
+
+	hmu->assoc_id = assoc_id;
+	hmu->index = index;
+	hmu->base = regs->hmu;
+	dev = &hmu->dev;
+	device_initialize(dev);
+	device_set_pm_not_required(dev);
+	dev->parent = parent;
+	dev->bus = &cxl_bus_type;
+	dev->type = &cxl_hmu_type;
+	rc = dev_set_name(dev, "hmu_mem%d.%d", assoc_id, index);
+	if (rc)
+		goto err;
+
+	rc = device_add(dev);
+	if (rc)
+		goto err;
+
+	return devm_add_action_or_reset(parent, remove_dev, dev);
+
+err:
+	put_device(&hmu->dev);
+	return rc;
+}
+EXPORT_SYMBOL_NS_GPL(devm_cxl_hmu_add, CXL);
+
diff --git a/drivers/cxl/core/regs.c b/drivers/cxl/core/regs.c
index e1082e749c69..c12afaa6ef98 100644
--- a/drivers/cxl/core/regs.c
+++ b/drivers/cxl/core/regs.c
@@ -401,6 +401,20 @@ int cxl_map_pmu_regs(struct cxl_register_map *map, struct cxl_pmu_regs *regs)
 }
 EXPORT_SYMBOL_NS_GPL(cxl_map_pmu_regs, CXL);
 
+int cxl_map_hmu_regs(struct cxl_register_map *map, struct cxl_hmu_regs *regs)
+{
+	struct device *dev = map->host;
+	resource_size_t phys_addr;
+
+	phys_addr = map->resource;
+	regs->hmu = devm_cxl_iomap_block(dev, phys_addr, map->max_size);
+	if (!regs->hmu)
+		return -ENOMEM;
+
+	return 0;
+}
+EXPORT_SYMBOL_NS_GPL(cxl_map_hmu_regs, CXL);
+
 static int cxl_map_regblock(struct cxl_register_map *map)
 {
 	struct device *host = map->host;
diff --git a/drivers/cxl/cxl.h b/drivers/cxl/cxl.h
index 5406e3ab3d4a..8172bc1f7a8d 100644
--- a/drivers/cxl/cxl.h
+++ b/drivers/cxl/cxl.h
@@ -227,6 +227,9 @@ struct cxl_regs {
 	struct_group_tagged(cxl_pmu_regs, pmu_regs,
 		void __iomem *pmu;
 	);
+	struct_group_tagged(cxl_hmu_regs, hmu_regs,
+		void __iomem *hmu;
+	);
 
 	/*
 	 * RCH downstream port specific RAS register
@@ -292,6 +295,7 @@ int cxl_map_component_regs(const struct cxl_register_map *map,
 			   unsigned long map_mask);
 int cxl_map_device_regs(const struct cxl_register_map *map,
 			struct cxl_device_regs *regs);
+int cxl_map_hmu_regs(struct cxl_register_map *map, struct cxl_hmu_regs *regs);
 int cxl_map_pmu_regs(struct cxl_register_map *map, struct cxl_pmu_regs *regs);
 
 enum cxl_regloc_type;
diff --git a/drivers/cxl/cxlpci.h b/drivers/cxl/cxlpci.h
index 4da07727ab9c..71f5e9620137 100644
--- a/drivers/cxl/cxlpci.h
+++ b/drivers/cxl/cxlpci.h
@@ -67,6 +67,7 @@ enum cxl_regloc_type {
 	CXL_REGLOC_RBI_VIRT,
 	CXL_REGLOC_RBI_MEMDEV,
 	CXL_REGLOC_RBI_PMU,
+	CXL_REGLOC_RBI_HMU,
 	CXL_REGLOC_RBI_TYPES
 };
 
diff --git a/drivers/cxl/hmu.h b/drivers/cxl/hmu.h
new file mode 100644
index 000000000000..c4798ed9764b
--- /dev/null
+++ b/drivers/cxl/hmu.h
@@ -0,0 +1,23 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Copyright(c) 2024 Huawei
+ * CXL Specification rev 3.2 Setion 8.2.8 (CHMU Register Interface)
+ */
+#ifndef CXL_HMU_H
+#define CXL_HMU_H
+#include <linux/device.h>
+
+#define CXL_HMU_REGMAP_SIZE 0xe00 /* Table 8-32 CXL 3.0 specification */
+struct cxl_hmu {
+	struct device dev;
+	void __iomem *base;
+	int assoc_id;
+	int index;
+};
+
+#define to_cxl_hmu(dev) container_of(dev, struct cxl_hmu, dev)
+struct cxl_hmu_regs;
+int devm_cxl_hmu_add(struct device *parent, struct cxl_hmu_regs *regs,
+		     int assoc_id, int idx);
+
+#endif
diff --git a/drivers/cxl/pci.c b/drivers/cxl/pci.c
index 188412d45e0d..e89ea9d3f007 100644
--- a/drivers/cxl/pci.c
+++ b/drivers/cxl/pci.c
@@ -15,6 +15,7 @@
 #include "cxlmem.h"
 #include "cxlpci.h"
 #include "cxl.h"
+#include "hmu.h"
 #include "pmu.h"
 
 /**
@@ -814,7 +815,7 @@ static int cxl_pci_probe(struct pci_dev *pdev, const struct pci_device_id *id)
 	struct cxl_dev_state *cxlds;
 	struct cxl_register_map map;
 	struct cxl_memdev *cxlmd;
-	int i, rc, pmu_count;
+	int i, rc, hmu_count, pmu_count;
 	bool irq_avail;
 
 	/*
@@ -938,6 +939,29 @@ static int cxl_pci_probe(struct pci_dev *pdev, const struct pci_device_id *id)
 		}
 	}
 
+	hmu_count = cxl_count_regblock(pdev, CXL_REGLOC_RBI_HMU);
+	for (i = 0; i < hmu_count; i++) {
+		struct cxl_hmu_regs hmu_regs;
+
+		rc = cxl_find_regblock_instance(pdev, CXL_REGLOC_RBI_HMU, &map, i);
+		if (rc) {
+			dev_dbg(&pdev->dev, "Could not find HMU regblock\n");
+			break;
+		}
+
+		rc = cxl_map_hmu_regs(&map, &hmu_regs);
+		if (rc) {
+			dev_dbg(&pdev->dev, "Could not map HMU regs\n");
+			break;
+		}
+
+		rc = devm_cxl_hmu_add(cxlds->dev, &hmu_regs, cxlmd->id, i);
+		if (rc) {
+			dev_dbg(&pdev->dev, "Could not add HMU instance\n");
+			break;
+		}
+	}
+
 	rc = cxl_event_config(host_bridge, mds, irq_avail);
 	if (rc)
 		return rc;
-- 
2.43.0