cxl: Driver code for powernv PCIe based cards for userspace access

This is the core of the cxl driver.

It adds support for using cxl cards in the powernv environment only (ie POWER8
bare metal). It allows access to cxl accelerators by userspace using the
/dev/cxl/afuM.N char devices.

The kernel driver has no knowledge of the function implemented by the
accelerator. It provides services to userspace via the /dev/cxl/afuM.N
devices. When a program opens this device and runs the start work IOCTL, the
accelerator will have coherent access to that processes memory using the same
virtual addresses. That process may mmap the device to access any MMIO space
the accelerator provides.  Also, reads on the device will allow interrupts to
be received. These services are further documented in a later patch in
Documentation/powerpc/cxl.txt.

Documentation of the cxl hardware architecture and userspace API is provided in
subsequent patches.

Signed-off-by: Ian Munsie <imunsie@au1.ibm.com>
Signed-off-by: Michael Neuling <mikey@neuling.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

1 files changed, 402 insertions, 0 deletions

diff --git a/drivers/misc/cxl/irq.c b/drivers/misc/cxl/irq.c
new file mode 100644
index 000000000000..336020c8e1af
--- /dev/null
+++ b/drivers/misc/cxl/irq.c
@@ -0,0 +1,402 @@
+/*
+ * Copyright 2014 IBM Corp.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version
+ * 2 of the License, or (at your option) any later version.
+ */
+
+#include <linux/interrupt.h>
+#include <linux/workqueue.h>
+#include <linux/sched.h>
+#include <linux/wait.h>
+#include <linux/slab.h>
+#include <linux/pid.h>
+#include <asm/cputable.h>
+#include <misc/cxl.h>
+
+#include "cxl.h"
+
+/* XXX: This is implementation specific */
+static irqreturn_t handle_psl_slice_error(struct cxl_context *ctx, u64 dsisr, u64 errstat)
+{
+	u64 fir1, fir2, fir_slice, serr, afu_debug;
+
+	fir1 = cxl_p1_read(ctx->afu->adapter, CXL_PSL_FIR1);
+	fir2 = cxl_p1_read(ctx->afu->adapter, CXL_PSL_FIR2);
+	fir_slice = cxl_p1n_read(ctx->afu, CXL_PSL_FIR_SLICE_An);
+	serr = cxl_p1n_read(ctx->afu, CXL_PSL_SERR_An);
+	afu_debug = cxl_p1n_read(ctx->afu, CXL_AFU_DEBUG_An);
+
+	dev_crit(&ctx->afu->dev, "PSL ERROR STATUS: 0x%.16llx\n", errstat);
+	dev_crit(&ctx->afu->dev, "PSL_FIR1: 0x%.16llx\n", fir1);
+	dev_crit(&ctx->afu->dev, "PSL_FIR2: 0x%.16llx\n", fir2);
+	dev_crit(&ctx->afu->dev, "PSL_SERR_An: 0x%.16llx\n", serr);
+	dev_crit(&ctx->afu->dev, "PSL_FIR_SLICE_An: 0x%.16llx\n", fir_slice);
+	dev_crit(&ctx->afu->dev, "CXL_PSL_AFU_DEBUG_An: 0x%.16llx\n", afu_debug);
+
+	dev_crit(&ctx->afu->dev, "STOPPING CXL TRACE\n");
+	cxl_stop_trace(ctx->afu->adapter);
+
+	return cxl_ack_irq(ctx, 0, errstat);
+}
+
+irqreturn_t cxl_slice_irq_err(int irq, void *data)
+{
+	struct cxl_afu *afu = data;
+	u64 fir_slice, errstat, serr, afu_debug;
+
+	WARN(irq, "CXL SLICE ERROR interrupt %i\n", irq);
+
+	serr = cxl_p1n_read(afu, CXL_PSL_SERR_An);
+	fir_slice = cxl_p1n_read(afu, CXL_PSL_FIR_SLICE_An);
+	errstat = cxl_p2n_read(afu, CXL_PSL_ErrStat_An);
+	afu_debug = cxl_p1n_read(afu, CXL_AFU_DEBUG_An);
+	dev_crit(&afu->dev, "PSL_SERR_An: 0x%.16llx\n", serr);
+	dev_crit(&afu->dev, "PSL_FIR_SLICE_An: 0x%.16llx\n", fir_slice);
+	dev_crit(&afu->dev, "CXL_PSL_ErrStat_An: 0x%.16llx\n", errstat);
+	dev_crit(&afu->dev, "CXL_PSL_AFU_DEBUG_An: 0x%.16llx\n", afu_debug);
+
+	cxl_p1n_write(afu, CXL_PSL_SERR_An, serr);
+
+	return IRQ_HANDLED;
+}
+
+static irqreturn_t cxl_irq_err(int irq, void *data)
+{
+	struct cxl *adapter = data;
+	u64 fir1, fir2, err_ivte;
+
+	WARN(1, "CXL ERROR interrupt %i\n", irq);
+
+	err_ivte = cxl_p1_read(adapter, CXL_PSL_ErrIVTE);
+	dev_crit(&adapter->dev, "PSL_ErrIVTE: 0x%.16llx\n", err_ivte);
+
+	dev_crit(&adapter->dev, "STOPPING CXL TRACE\n");
+	cxl_stop_trace(adapter);
+
+	fir1 = cxl_p1_read(adapter, CXL_PSL_FIR1);
+	fir2 = cxl_p1_read(adapter, CXL_PSL_FIR2);
+
+	dev_crit(&adapter->dev, "PSL_FIR1: 0x%.16llx\nPSL_FIR2: 0x%.16llx\n", fir1, fir2);
+
+	return IRQ_HANDLED;
+}
+
+static irqreturn_t schedule_cxl_fault(struct cxl_context *ctx, u64 dsisr, u64 dar)
+{
+	ctx->dsisr = dsisr;
+	ctx->dar = dar;
+	schedule_work(&ctx->fault_work);
+	return IRQ_HANDLED;
+}
+
+static irqreturn_t cxl_irq(int irq, void *data)
+{
+	struct cxl_context *ctx = data;
+	struct cxl_irq_info irq_info;
+	u64 dsisr, dar;
+	int result;
+
+	if ((result = cxl_get_irq(ctx, &irq_info))) {
+		WARN(1, "Unable to get CXL IRQ Info: %i\n", result);
+		return IRQ_HANDLED;
+	}
+
+	dsisr = irq_info.dsisr;
+	dar = irq_info.dar;
+
+	pr_devel("CXL interrupt %i for afu pe: %i DSISR: %#llx DAR: %#llx\n", irq, ctx->pe, dsisr, dar);
+
+	if (dsisr & CXL_PSL_DSISR_An_DS) {
+		/*
+		 * We don't inherently need to sleep to handle this, but we do
+		 * need to get a ref to the task's mm, which we can't do from
+		 * irq context without the potential for a deadlock since it
+		 * takes the task_lock. An alternate option would be to keep a
+		 * reference to the task's mm the entire time it has cxl open,
+		 * but to do that we need to solve the issue where we hold a
+		 * ref to the mm, but the mm can hold a ref to the fd after an
+		 * mmap preventing anything from being cleaned up.
+		 */
+		pr_devel("Scheduling segment miss handling for later pe: %i\n", ctx->pe);
+		return schedule_cxl_fault(ctx, dsisr, dar);
+	}
+
+	if (dsisr & CXL_PSL_DSISR_An_M)
+		pr_devel("CXL interrupt: PTE not found\n");
+	if (dsisr & CXL_PSL_DSISR_An_P)
+		pr_devel("CXL interrupt: Storage protection violation\n");
+	if (dsisr & CXL_PSL_DSISR_An_A)
+		pr_devel("CXL interrupt: AFU lock access to write through or cache inhibited storage\n");
+	if (dsisr & CXL_PSL_DSISR_An_S)
+		pr_devel("CXL interrupt: Access was afu_wr or afu_zero\n");
+	if (dsisr & CXL_PSL_DSISR_An_K)
+		pr_devel("CXL interrupt: Access not permitted by virtual page class key protection\n");
+
+	if (dsisr & CXL_PSL_DSISR_An_DM) {
+		/*
+		 * In some cases we might be able to handle the fault
+		 * immediately if hash_page would succeed, but we still need
+		 * the task's mm, which as above we can't get without a lock
+		 */
+		pr_devel("Scheduling page fault handling for later pe: %i\n", ctx->pe);
+		return schedule_cxl_fault(ctx, dsisr, dar);
+	}
+	if (dsisr & CXL_PSL_DSISR_An_ST)
+		WARN(1, "CXL interrupt: Segment Table PTE not found\n");
+	if (dsisr & CXL_PSL_DSISR_An_UR)
+		pr_devel("CXL interrupt: AURP PTE not found\n");
+	if (dsisr & CXL_PSL_DSISR_An_PE)
+		return handle_psl_slice_error(ctx, dsisr, irq_info.errstat);
+	if (dsisr & CXL_PSL_DSISR_An_AE) {
+		pr_devel("CXL interrupt: AFU Error %.llx\n", irq_info.afu_err);
+
+		if (ctx->pending_afu_err) {
+			/*
+			 * This shouldn't happen - the PSL treats these errors
+			 * as fatal and will have reset the AFU, so there's not
+			 * much point buffering multiple AFU errors.
+			 * OTOH if we DO ever see a storm of these come in it's
+			 * probably best that we log them somewhere:
+			 */
+			dev_err_ratelimited(&ctx->afu->dev, "CXL AFU Error "
+					    "undelivered to pe %i: %.llx\n",
+					    ctx->pe, irq_info.afu_err);
+		} else {
+			spin_lock(&ctx->lock);
+			ctx->afu_err = irq_info.afu_err;
+			ctx->pending_afu_err = 1;
+			spin_unlock(&ctx->lock);
+
+			wake_up_all(&ctx->wq);
+		}
+
+		cxl_ack_irq(ctx, CXL_PSL_TFC_An_A, 0);
+	}
+	if (dsisr & CXL_PSL_DSISR_An_OC)
+		pr_devel("CXL interrupt: OS Context Warning\n");
+
+	WARN(1, "Unhandled CXL PSL IRQ\n");
+	return IRQ_HANDLED;
+}
+
+static irqreturn_t cxl_irq_multiplexed(int irq, void *data)
+{
+	struct cxl_afu *afu = data;
+	struct cxl_context *ctx;
+	int ph = cxl_p2n_read(afu, CXL_PSL_PEHandle_An) & 0xffff;
+	int ret;
+
+	rcu_read_lock();
+	ctx = idr_find(&afu->contexts_idr, ph);
+	if (ctx) {
+		ret = cxl_irq(irq, ctx);
+		rcu_read_unlock();
+		return ret;
+	}
+	rcu_read_unlock();
+
+	WARN(1, "Unable to demultiplex CXL PSL IRQ\n");
+	return IRQ_HANDLED;
+}
+
+static irqreturn_t cxl_irq_afu(int irq, void *data)
+{
+	struct cxl_context *ctx = data;
+	irq_hw_number_t hwirq = irqd_to_hwirq(irq_get_irq_data(irq));
+	int irq_off, afu_irq = 1;
+	__u16 range;
+	int r;
+
+	for (r = 1; r < CXL_IRQ_RANGES; r++) {
+		irq_off = hwirq - ctx->irqs.offset[r];
+		range = ctx->irqs.range[r];
+		if (irq_off >= 0 && irq_off < range) {
+			afu_irq += irq_off;
+			break;
+		}
+		afu_irq += range;
+	}
+	if (unlikely(r >= CXL_IRQ_RANGES)) {
+		WARN(1, "Recieved AFU IRQ out of range for pe %i (virq %i hwirq %lx)\n",
+		     ctx->pe, irq, hwirq);
+		return IRQ_HANDLED;
+	}
+
+	pr_devel("Received AFU interrupt %i for pe: %i (virq %i hwirq %lx)\n",
+	       afu_irq, ctx->pe, irq, hwirq);
+
+	if (unlikely(!ctx->irq_bitmap)) {
+		WARN(1, "Recieved AFU IRQ for context with no IRQ bitmap\n");
+		return IRQ_HANDLED;
+	}
+	spin_lock(&ctx->lock);
+	set_bit(afu_irq - 1, ctx->irq_bitmap);
+	ctx->pending_irq = true;
+	spin_unlock(&ctx->lock);
+
+	wake_up_all(&ctx->wq);
+
+	return IRQ_HANDLED;
+}
+
+unsigned int cxl_map_irq(struct cxl *adapter, irq_hw_number_t hwirq,
+			 irq_handler_t handler, void *cookie)
+{
+	unsigned int virq;
+	int result;
+
+	/* IRQ Domain? */
+	virq = irq_create_mapping(NULL, hwirq);
+	if (!virq) {
+		dev_warn(&adapter->dev, "cxl_map_irq: irq_create_mapping failed\n");
+		return 0;
+	}
+
+	cxl_setup_irq(adapter, hwirq, virq);
+
+	pr_devel("hwirq %#lx mapped to virq %u\n", hwirq, virq);
+
+	result = request_irq(virq, handler, 0, "cxl", cookie);
+	if (result) {
+		dev_warn(&adapter->dev, "cxl_map_irq: request_irq failed: %i\n", result);
+		return 0;
+	}
+
+	return virq;
+}
+
+void cxl_unmap_irq(unsigned int virq, void *cookie)
+{
+	free_irq(virq, cookie);
+	irq_dispose_mapping(virq);
+}
+
+static int cxl_register_one_irq(struct cxl *adapter,
+				irq_handler_t handler,
+				void *cookie,
+				irq_hw_number_t *dest_hwirq,
+				unsigned int *dest_virq)
+{
+	int hwirq, virq;
+
+	if ((hwirq = cxl_alloc_one_irq(adapter)) < 0)
+		return hwirq;
+
+	if (!(virq = cxl_map_irq(adapter, hwirq, handler, cookie)))
+		goto err;
+
+	*dest_hwirq = hwirq;
+	*dest_virq = virq;
+
+	return 0;
+
+err:
+	cxl_release_one_irq(adapter, hwirq);
+	return -ENOMEM;
+}
+
+int cxl_register_psl_err_irq(struct cxl *adapter)
+{
+	int rc;
+
+	if ((rc = cxl_register_one_irq(adapter, cxl_irq_err, adapter,
+				       &adapter->err_hwirq,
+				       &adapter->err_virq)))
+		return rc;
+
+	cxl_p1_write(adapter, CXL_PSL_ErrIVTE, adapter->err_hwirq & 0xffff);
+
+	return 0;
+}
+
+void cxl_release_psl_err_irq(struct cxl *adapter)
+{
+	cxl_p1_write(adapter, CXL_PSL_ErrIVTE, 0x0000000000000000);
+	cxl_unmap_irq(adapter->err_virq, adapter);
+	cxl_release_one_irq(adapter, adapter->err_hwirq);
+}
+
+int cxl_register_serr_irq(struct cxl_afu *afu)
+{
+	u64 serr;
+	int rc;
+
+	if ((rc = cxl_register_one_irq(afu->adapter, cxl_slice_irq_err, afu,
+				       &afu->serr_hwirq,
+				       &afu->serr_virq)))
+		return rc;
+
+	serr = cxl_p1n_read(afu, CXL_PSL_SERR_An);
+	serr = (serr & 0x00ffffffffff0000ULL) | (afu->serr_hwirq & 0xffff);
+	cxl_p1n_write(afu, CXL_PSL_SERR_An, serr);
+
+	return 0;
+}
+
+void cxl_release_serr_irq(struct cxl_afu *afu)
+{
+	cxl_p1n_write(afu, CXL_PSL_SERR_An, 0x0000000000000000);
+	cxl_unmap_irq(afu->serr_virq, afu);
+	cxl_release_one_irq(afu->adapter, afu->serr_hwirq);
+}
+
+int cxl_register_psl_irq(struct cxl_afu *afu)
+{
+	return cxl_register_one_irq(afu->adapter, cxl_irq_multiplexed, afu,
+			&afu->psl_hwirq, &afu->psl_virq);
+}
+
+void cxl_release_psl_irq(struct cxl_afu *afu)
+{
+	cxl_unmap_irq(afu->psl_virq, afu);
+	cxl_release_one_irq(afu->adapter, afu->psl_hwirq);
+}
+
+int afu_register_irqs(struct cxl_context *ctx, u32 count)
+{
+	irq_hw_number_t hwirq;
+	int rc, r, i;
+
+	if ((rc = cxl_alloc_irq_ranges(&ctx->irqs, ctx->afu->adapter, count)))
+		return rc;
+
+	/* Multiplexed PSL Interrupt */
+	ctx->irqs.offset[0] = ctx->afu->psl_hwirq;
+	ctx->irqs.range[0] = 1;
+
+	ctx->irq_count = count;
+	ctx->irq_bitmap = kcalloc(BITS_TO_LONGS(count),
+				  sizeof(*ctx->irq_bitmap), GFP_KERNEL);
+	if (!ctx->irq_bitmap)
+		return -ENOMEM;
+	for (r = 1; r < CXL_IRQ_RANGES; r++) {
+		hwirq = ctx->irqs.offset[r];
+		for (i = 0; i < ctx->irqs.range[r]; hwirq++, i++) {
+			cxl_map_irq(ctx->afu->adapter, hwirq,
+				     cxl_irq_afu, ctx);
+		}
+	}
+
+	return 0;
+}
+
+void afu_release_irqs(struct cxl_context *ctx)
+{
+	irq_hw_number_t hwirq;
+	unsigned int virq;
+	int r, i;
+
+	for (r = 1; r < CXL_IRQ_RANGES; r++) {
+		hwirq = ctx->irqs.offset[r];
+		for (i = 0; i < ctx->irqs.range[r]; hwirq++, i++) {
+			virq = irq_find_mapping(NULL, hwirq);
+			if (virq)
+				cxl_unmap_irq(virq, ctx);
+		}
+	}
+
+	cxl_release_irq_ranges(&ctx->irqs, ctx->afu->adapter);
+}