[PATCH v12 2/2] iommu/riscv: create a auxiliary device for HPM

[Zong Li]

Create an auxiliary device for HPM when the IOMMU supports a
hardware performance monitor.

Tested-by: Chen Pei <cp0613@xxxxxxxxxxxxxxxxx>
Tested-by: Fangyu Yu <fangyu.yu@xxxxxxxxxxxxxxxxx>
Reviewed-by: Nutty Liu <nutty.liu@xxxxxxxxxxx>
Reviewed-by: Guo Ren <guoren@xxxxxxxxxx>
Reviewed-by: Yicong Yang <yang.yicong@xxxxxxxxxxxxx>
Suggested-by: Samuel Holland <samuel.holland@xxxxxxxxxx>
Signed-off-by: Zong Li <zong.li@xxxxxxxxxx>
---
 drivers/iommu/riscv/Kconfig |  1 +
 drivers/iommu/riscv/iommu.c | 48 +++++++++++++++++++++++++++++++++++++
 drivers/iommu/riscv/iommu.h |  4 ++++
 3 files changed, 53 insertions(+)

diff --git a/drivers/iommu/riscv/Kconfig b/drivers/iommu/riscv/Kconfig
index b86e5ab94183..8025bf0fb67f 100644
--- a/drivers/iommu/riscv/Kconfig
+++ b/drivers/iommu/riscv/Kconfig
@@ -10,6 +10,7 @@ config RISCV_IOMMU
 	select GENERIC_PT
 	select IOMMU_PT
 	select IOMMU_PT_RISCV64
+	select AUXILIARY_BUS
 	help
 	  Support for implementations of the RISC-V IOMMU architecture that
 	  complements the RISC-V MMU capabilities, providing similar address
diff --git a/drivers/iommu/riscv/iommu.c b/drivers/iommu/riscv/iommu.c
index fe8e6d0f8a23..3c8f8adba647 100644
--- a/drivers/iommu/riscv/iommu.c
+++ b/drivers/iommu/riscv/iommu.c
@@ -14,6 +14,7 @@
 
 #include <linux/acpi.h>
 #include <linux/acpi_rimt.h>
+#include <linux/auxiliary_bus.h>
 #include <linux/compiler.h>
 #include <linux/crash_dump.h>
 #include <linux/init.h>
@@ -48,6 +49,9 @@
 static DEFINE_IDA(riscv_iommu_pscids);
 #define RISCV_IOMMU_MAX_PSCID		(BIT(20) - 1)
 
+/* IOMMU PMU auxiliary device id allocation namespace. */
+static DEFINE_IDA(riscv_iommu_pmu_ida);
+
 /* Device resource-managed allocations */
 struct riscv_iommu_devres {
 	void *addr;
@@ -587,6 +591,46 @@ static irqreturn_t riscv_iommu_fltq_process(int irq, void *data)
 	return IRQ_HANDLED;
 }
 
+/*
+ * IOMMU Hardware performance monitor
+ */
+static void riscv_iommu_pmu_id_free(void *data)
+{
+	ida_free(&riscv_iommu_pmu_ida, (unsigned long)data);
+}
+
+static int riscv_iommu_hpm_enable(struct riscv_iommu_device *iommu)
+{
+	struct auxiliary_device *auxdev;
+	int id, ret;
+
+	id = ida_alloc(&riscv_iommu_pmu_ida, GFP_KERNEL);
+	if (id < 0)
+		return id;
+
+	ret = devm_add_action_or_reset(iommu->dev, riscv_iommu_pmu_id_free,
+				       (void *)(unsigned long)id);
+	if (ret)
+		return ret;
+
+	auxdev = auxiliary_device_create(iommu->dev, "riscv-iommu",
+					 "pmu", iommu, id);
+	if (!auxdev)
+		return -ENODEV;
+
+	iommu->pmu_dev = auxdev;
+	return 0;
+}
+
+static void riscv_iommu_hpm_disable(struct riscv_iommu_device *iommu)
+{
+	if (!iommu->pmu_dev)
+		return;
+
+	auxiliary_device_destroy(iommu->pmu_dev);
+	iommu->pmu_dev = NULL;
+}
+
 /* Lookup and initialize device context info structure. */
 static struct riscv_iommu_dc *riscv_iommu_get_dc(struct riscv_iommu_device *iommu,
 						 unsigned int devid)
@@ -1570,6 +1614,7 @@ static int riscv_iommu_init_check(struct riscv_iommu_device *iommu)
 
 void riscv_iommu_remove(struct riscv_iommu_device *iommu)
 {
+	riscv_iommu_hpm_disable(iommu);
 	iommu_device_unregister(&iommu->iommu);
 	iommu_device_sysfs_remove(&iommu->iommu);
 	riscv_iommu_iodir_set_mode(iommu, RISCV_IOMMU_DDTP_IOMMU_MODE_OFF);
@@ -1636,6 +1681,9 @@ int riscv_iommu_init(struct riscv_iommu_device *iommu)
 		goto err_remove_sysfs;
 	}
 
+	if (iommu->caps & RISCV_IOMMU_CAPABILITIES_HPM)
+		riscv_iommu_hpm_enable(iommu);
+
 	return 0;
 
 err_remove_sysfs:
diff --git a/drivers/iommu/riscv/iommu.h b/drivers/iommu/riscv/iommu.h
index 5676001548cc..7fcd79fa47c8 100644
--- a/drivers/iommu/riscv/iommu.h
+++ b/drivers/iommu/riscv/iommu.h
@@ -19,6 +19,7 @@
 #include "iommu-bits.h"
 
 struct riscv_iommu_device;
+struct auxiliary_device;
 
 struct riscv_iommu_queue {
 	atomic_t prod;				/* unbounded producer allocation index */
@@ -62,6 +63,9 @@ struct riscv_iommu_device {
 	unsigned int ddt_mode;
 	dma_addr_t ddt_phys;
 	u64 *ddt_root;
+
+	/* PMU auxiliary device; torn down explicitly before MSI teardown */
+	struct auxiliary_device *pmu_dev;
 };
 
 int riscv_iommu_init(struct riscv_iommu_device *iommu);
-- 
2.43.7