linux-kernel - [PATCH 2/2] iommu/riscv: support HPM and interrupt handling

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Message-Id: <20250115030306.29735-3-zong.li@sifive.com>
Date: Wed, 15 Jan 2025 11:03:06 +0800
From: Zong Li <zong.li@...ive.com>
To: joro@...tes.org,
	will@...nel.org,
	robin.murphy@....com,
	tjeznach@...osinc.com,
	paul.walmsley@...ive.com,
	palmer@...belt.com,
	aou@...s.berkeley.edu,
	luxu.kernel@...edance.com,
	linux-kernel@...r.kernel.org,
	iommu@...ts.linux.dev,
	linux-riscv@...ts.infradead.org
Cc: Zong Li <zong.li@...ive.com>
Subject: [PATCH 2/2] iommu/riscv: support HPM and interrupt handling

Initialize the PMU and uninitialize it when driver is removed.
Interrupt handling is also implemented, and the handler needs
to be a primary handler instead of a threaded function because
pt_regs is empty when threading the IRQ. However, pt_regs is
required by perf_event_overflow.

Signed-off-by: Zong Li <zong.li@...ive.com>
Tested-by: Xu Lu <luxu.kernel@...edance.com>
---
 drivers/iommu/riscv/iommu.c | 65 +++++++++++++++++++++++++++++++++++++
 1 file changed, 65 insertions(+)

diff --git a/drivers/iommu/riscv/iommu.c b/drivers/iommu/riscv/iommu.c
index 8a05def774bd..20ae90471484 100644
--- a/drivers/iommu/riscv/iommu.c
+++ b/drivers/iommu/riscv/iommu.c
@@ -552,6 +552,62 @@ static irqreturn_t riscv_iommu_fltq_process(int irq, void *data)
 	return IRQ_HANDLED;
 }
 
+/*
+ * IOMMU Hardware performance monitor
+ */
+
+/* HPM interrupt primary handler */
+static irqreturn_t riscv_iommu_hpm_irq_handler(int irq, void *dev_id)
+{
+	struct riscv_iommu_device *iommu = (struct riscv_iommu_device *)dev_id;
+
+	/* Clear performance monitoring interrupt pending */
+	riscv_iommu_writel(iommu, RISCV_IOMMU_REG_IPSR, RISCV_IOMMU_IPSR_PMIP);
+
+	/* Process pmu irq */
+	riscv_iommu_pmu_handle_irq(&iommu->pmu);
+
+	return IRQ_HANDLED;
+}
+
+/* HPM initialization */
+static int riscv_iommu_hpm_enable(struct riscv_iommu_device *iommu)
+{
+	int rc;
+
+	if (!(iommu->caps & RISCV_IOMMU_CAPABILITIES_HPM))
+		return 0;
+
+	/*
+	 * pt_regs is empty when threading the IRQ, but pt_regs is necessary
+	 * by perf_event_overflow. Use primary handler instead of thread
+	 * function for PM IRQ.
+	 *
+	 * Set the IRQF_ONESHOT flag because this IRQ might be shared with
+	 * other threaded IRQs by other queues.
+	 */
+	rc = devm_request_irq(iommu->dev,
+			      iommu->irqs[riscv_iommu_queue_vec(iommu, RISCV_IOMMU_IPSR_PMIP)],
+			      riscv_iommu_hpm_irq_handler, IRQF_ONESHOT | IRQF_SHARED, NULL, iommu);
+	if (rc)
+		return rc;
+
+	return riscv_iommu_pmu_init(&iommu->pmu, iommu->reg, dev_name(iommu->dev));
+}
+
+/* HPM uninitialization */
+static void riscv_iommu_hpm_disable(struct riscv_iommu_device *iommu)
+{
+	if (!(iommu->caps & RISCV_IOMMU_CAPABILITIES_HPM))
+		return;
+
+	devm_free_irq(iommu->dev,
+		      iommu->irqs[riscv_iommu_queue_vec(iommu, RISCV_IOMMU_IPSR_PMIP)],
+		      iommu);
+
+	riscv_iommu_pmu_uninit(&iommu->pmu);
+}
+
 /* Lookup and initialize device context info structure. */
 static struct riscv_iommu_dc *riscv_iommu_get_dc(struct riscv_iommu_device *iommu,
 						 unsigned int devid)
@@ -1596,6 +1652,9 @@ void riscv_iommu_remove(struct riscv_iommu_device *iommu)
 	riscv_iommu_iodir_set_mode(iommu, RISCV_IOMMU_DDTP_IOMMU_MODE_OFF);
 	riscv_iommu_queue_disable(&iommu->cmdq);
 	riscv_iommu_queue_disable(&iommu->fltq);
+
+	if (iommu->caps & RISCV_IOMMU_CAPABILITIES_HPM)
+		riscv_iommu_pmu_uninit(&iommu->pmu);
 }
 
 int riscv_iommu_init(struct riscv_iommu_device *iommu)
@@ -1635,6 +1694,10 @@ int riscv_iommu_init(struct riscv_iommu_device *iommu)
 	if (rc)
 		goto err_queue_disable;
 
+	rc = riscv_iommu_hpm_enable(iommu);
+	if (rc)
+		goto err_hpm_disable;
+
 	rc = iommu_device_sysfs_add(&iommu->iommu, NULL, NULL, "riscv-iommu@%s",
 				    dev_name(iommu->dev));
 	if (rc) {
@@ -1653,6 +1716,8 @@ int riscv_iommu_init(struct riscv_iommu_device *iommu)
 err_remove_sysfs:
 	iommu_device_sysfs_remove(&iommu->iommu);
 err_iodir_off:
+	riscv_iommu_hpm_disable(iommu);
+err_hpm_disable:
 	riscv_iommu_iodir_set_mode(iommu, RISCV_IOMMU_DDTP_IOMMU_MODE_OFF);
 err_queue_disable:
 	riscv_iommu_queue_disable(&iommu->fltq);
-- 
2.17.1