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, 508 insertions, 0 deletions

diff --git a/drivers/misc/cxl/file.c b/drivers/misc/cxl/file.c
new file mode 100644
index 000000000000..847b7e646a7e
--- /dev/null
+++ b/drivers/misc/cxl/file.c
@@ -0,0 +1,508 @@
+/*
+ * 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/spinlock.h>
+#include <linux/module.h>
+#include <linux/export.h>
+#include <linux/kernel.h>
+#include <linux/bitmap.h>
+#include <linux/sched.h>
+#include <linux/poll.h>
+#include <linux/pid.h>
+#include <linux/fs.h>
+#include <linux/mm.h>
+#include <linux/slab.h>
+#include <asm/cputable.h>
+#include <asm/current.h>
+#include <asm/copro.h>
+
+#include "cxl.h"
+
+#define CXL_NUM_MINORS 256 /* Total to reserve */
+#define CXL_DEV_MINORS 13   /* 1 control + 4 AFUs * 3 (dedicated/master/shared) */
+
+#define CXL_CARD_MINOR(adapter) (adapter->adapter_num * CXL_DEV_MINORS)
+#define CXL_AFU_MINOR_D(afu) (CXL_CARD_MINOR(afu->adapter) + 1 + (3 * afu->slice))
+#define CXL_AFU_MINOR_M(afu) (CXL_AFU_MINOR_D(afu) + 1)
+#define CXL_AFU_MINOR_S(afu) (CXL_AFU_MINOR_D(afu) + 2)
+#define CXL_AFU_MKDEV_D(afu) MKDEV(MAJOR(cxl_dev), CXL_AFU_MINOR_D(afu))
+#define CXL_AFU_MKDEV_M(afu) MKDEV(MAJOR(cxl_dev), CXL_AFU_MINOR_M(afu))
+#define CXL_AFU_MKDEV_S(afu) MKDEV(MAJOR(cxl_dev), CXL_AFU_MINOR_S(afu))
+
+#define CXL_DEVT_ADAPTER(dev) (MINOR(dev) / CXL_DEV_MINORS)
+#define CXL_DEVT_AFU(dev) ((MINOR(dev) % CXL_DEV_MINORS - 1) / 3)
+
+#define CXL_DEVT_IS_CARD(dev) (MINOR(dev) % CXL_DEV_MINORS == 0)
+
+static dev_t cxl_dev;
+
+static struct class *cxl_class;
+
+static int __afu_open(struct inode *inode, struct file *file, bool master)
+{
+	struct cxl *adapter;
+	struct cxl_afu *afu;
+	struct cxl_context *ctx;
+	int adapter_num = CXL_DEVT_ADAPTER(inode->i_rdev);
+	int slice = CXL_DEVT_AFU(inode->i_rdev);
+	int rc = -ENODEV;
+
+	pr_devel("afu_open afu%i.%i\n", slice, adapter_num);
+
+	if (!(adapter = get_cxl_adapter(adapter_num)))
+		return -ENODEV;
+
+	if (slice > adapter->slices)
+		goto err_put_adapter;
+
+	spin_lock(&adapter->afu_list_lock);
+	if (!(afu = adapter->afu[slice])) {
+		spin_unlock(&adapter->afu_list_lock);
+		goto err_put_adapter;
+	}
+	get_device(&afu->dev);
+	spin_unlock(&adapter->afu_list_lock);
+
+	if (!afu->current_mode)
+		goto err_put_afu;
+
+	if (!(ctx = cxl_context_alloc())) {
+		rc = -ENOMEM;
+		goto err_put_afu;
+	}
+
+	if ((rc = cxl_context_init(ctx, afu, master)))
+		goto err_put_afu;
+
+	pr_devel("afu_open pe: %i\n", ctx->pe);
+	file->private_data = ctx;
+	cxl_ctx_get();
+
+	/* Our ref on the AFU will now hold the adapter */
+	put_device(&adapter->dev);
+
+	return 0;
+
+err_put_afu:
+	put_device(&afu->dev);
+err_put_adapter:
+	put_device(&adapter->dev);
+	return rc;
+}
+static int afu_open(struct inode *inode, struct file *file)
+{
+	return __afu_open(inode, file, false);
+}
+
+static int afu_master_open(struct inode *inode, struct file *file)
+{
+	return __afu_open(inode, file, true);
+}
+
+static int afu_release(struct inode *inode, struct file *file)
+{
+	struct cxl_context *ctx = file->private_data;
+
+	pr_devel("%s: closing cxl file descriptor. pe: %i\n",
+		 __func__, ctx->pe);
+	cxl_context_detach(ctx);
+
+	put_device(&ctx->afu->dev);
+
+	/*
+	 * At this this point all bottom halfs have finished and we should be
+	 * getting no more IRQs from the hardware for this context.  Once it's
+	 * removed from the IDR (and RCU synchronised) it's safe to free the
+	 * sstp and context.
+	 */
+	cxl_context_free(ctx);
+
+	cxl_ctx_put();
+	return 0;
+}
+
+static long afu_ioctl_start_work(struct cxl_context *ctx,
+				 struct cxl_ioctl_start_work __user *uwork)
+{
+	struct cxl_ioctl_start_work work;
+	u64 amr = 0;
+	int rc;
+
+	pr_devel("%s: pe: %i\n", __func__, ctx->pe);
+
+	mutex_lock(&ctx->status_mutex);
+	if (ctx->status != OPENED) {
+		rc = -EIO;
+		goto out;
+	}
+
+	if (copy_from_user(&work, uwork,
+			   sizeof(struct cxl_ioctl_start_work))) {
+		rc = -EFAULT;
+		goto out;
+	}
+
+	/*
+	 * if any of the reserved fields are set or any of the unused
+	 * flags are set it's invalid
+	 */
+	if (work.reserved1 || work.reserved2 || work.reserved3 ||
+	    work.reserved4 || work.reserved5 || work.reserved6 ||
+	    (work.flags & ~CXL_START_WORK_ALL)) {
+		rc = -EINVAL;
+		goto out;
+	}
+
+	if (!(work.flags & CXL_START_WORK_NUM_IRQS))
+		work.num_interrupts = ctx->afu->pp_irqs;
+	else if ((work.num_interrupts < ctx->afu->pp_irqs) ||
+		 (work.num_interrupts > ctx->afu->irqs_max)) {
+		rc =  -EINVAL;
+		goto out;
+	}
+	if ((rc = afu_register_irqs(ctx, work.num_interrupts)))
+		goto out;
+
+	if (work.flags & CXL_START_WORK_AMR)
+		amr = work.amr & mfspr(SPRN_UAMOR);
+
+	/*
+	 * We grab the PID here and not in the file open to allow for the case
+	 * where a process (master, some daemon, etc) has opened the chardev on
+	 * behalf of another process, so the AFU's mm gets bound to the process
+	 * that performs this ioctl and not the process that opened the file.
+	 */
+	ctx->pid = get_pid(get_task_pid(current, PIDTYPE_PID));
+
+	if ((rc = cxl_attach_process(ctx, false, work.work_element_descriptor,
+				     amr)))
+		goto out;
+
+	ctx->status = STARTED;
+	rc = 0;
+out:
+	mutex_unlock(&ctx->status_mutex);
+	return rc;
+}
+static long afu_ioctl_process_element(struct cxl_context *ctx,
+				      int __user *upe)
+{
+	pr_devel("%s: pe: %i\n", __func__, ctx->pe);
+
+	if (copy_to_user(upe, &ctx->pe, sizeof(__u32)))
+		return -EFAULT;
+
+	return 0;
+}
+
+static long afu_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
+{
+	struct cxl_context *ctx = file->private_data;
+
+	if (ctx->status == CLOSED)
+		return -EIO;
+
+	pr_devel("afu_ioctl\n");
+	switch (cmd) {
+	case CXL_IOCTL_START_WORK:
+		return afu_ioctl_start_work(ctx, (struct cxl_ioctl_start_work __user *)arg);
+	case CXL_IOCTL_GET_PROCESS_ELEMENT:
+		return afu_ioctl_process_element(ctx, (__u32 __user *)arg);
+	}
+	return -EINVAL;
+}
+
+static long afu_compat_ioctl(struct file *file, unsigned int cmd,
+			     unsigned long arg)
+{
+	return afu_ioctl(file, cmd, arg);
+}
+
+static int afu_mmap(struct file *file, struct vm_area_struct *vm)
+{
+	struct cxl_context *ctx = file->private_data;
+
+	/* AFU must be started before we can MMIO */
+	if (ctx->status != STARTED)
+		return -EIO;
+
+	return cxl_context_iomap(ctx, vm);
+}
+
+static unsigned int afu_poll(struct file *file, struct poll_table_struct *poll)
+{
+	struct cxl_context *ctx = file->private_data;
+	int mask = 0;
+	unsigned long flags;
+
+
+	poll_wait(file, &ctx->wq, poll);
+
+	pr_devel("afu_poll wait done pe: %i\n", ctx->pe);
+
+	spin_lock_irqsave(&ctx->lock, flags);
+	if (ctx->pending_irq || ctx->pending_fault ||
+	    ctx->pending_afu_err)
+		mask |= POLLIN | POLLRDNORM;
+	else if (ctx->status == CLOSED)
+		/* Only error on closed when there are no futher events pending
+		 */
+		mask |= POLLERR;
+	spin_unlock_irqrestore(&ctx->lock, flags);
+
+	pr_devel("afu_poll pe: %i returning %#x\n", ctx->pe, mask);
+
+	return mask;
+}
+
+static inline int ctx_event_pending(struct cxl_context *ctx)
+{
+	return (ctx->pending_irq || ctx->pending_fault ||
+	    ctx->pending_afu_err || (ctx->status == CLOSED));
+}
+
+static ssize_t afu_read(struct file *file, char __user *buf, size_t count,
+			loff_t *off)
+{
+	struct cxl_context *ctx = file->private_data;
+	struct cxl_event event;
+	unsigned long flags;
+	DEFINE_WAIT(wait);
+
+	if (count < CXL_READ_MIN_SIZE)
+		return -EINVAL;
+
+	spin_lock_irqsave(&ctx->lock, flags);
+
+	for (;;) {
+		prepare_to_wait(&ctx->wq, &wait, TASK_INTERRUPTIBLE);
+		if (ctx_event_pending(ctx))
+			break;
+
+		spin_unlock_irqrestore(&ctx->lock, flags);
+		if (file->f_flags & O_NONBLOCK)
+			return -EAGAIN;
+
+		if (signal_pending(current))
+			return -ERESTARTSYS;
+
+		pr_devel("afu_read going to sleep...\n");
+		schedule();
+		pr_devel("afu_read woken up\n");
+		spin_lock_irqsave(&ctx->lock, flags);
+	}
+
+	finish_wait(&ctx->wq, &wait);
+
+	memset(&event, 0, sizeof(event));
+	event.header.process_element = ctx->pe;
+	event.header.size = sizeof(struct cxl_event_header);
+	if (ctx->pending_irq) {
+		pr_devel("afu_read delivering AFU interrupt\n");
+		event.header.size += sizeof(struct cxl_event_afu_interrupt);
+		event.header.type = CXL_EVENT_AFU_INTERRUPT;
+		event.irq.irq = find_first_bit(ctx->irq_bitmap, ctx->irq_count) + 1;
+		clear_bit(event.irq.irq - 1, ctx->irq_bitmap);
+		if (bitmap_empty(ctx->irq_bitmap, ctx->irq_count))
+			ctx->pending_irq = false;
+	} else if (ctx->pending_fault) {
+		pr_devel("afu_read delivering data storage fault\n");
+		event.header.size += sizeof(struct cxl_event_data_storage);
+		event.header.type = CXL_EVENT_DATA_STORAGE;
+		event.fault.addr = ctx->fault_addr;
+		event.fault.dsisr = ctx->fault_dsisr;
+		ctx->pending_fault = false;
+	} else if (ctx->pending_afu_err) {
+		pr_devel("afu_read delivering afu error\n");
+		event.header.size += sizeof(struct cxl_event_afu_error);
+		event.header.type = CXL_EVENT_AFU_ERROR;
+		event.afu_error.error = ctx->afu_err;
+		ctx->pending_afu_err = false;
+	} else if (ctx->status == CLOSED) {
+		pr_devel("afu_read fatal error\n");
+		spin_unlock_irqrestore(&ctx->lock, flags);
+		return -EIO;
+	} else
+		WARN(1, "afu_read must be buggy\n");
+
+	spin_unlock_irqrestore(&ctx->lock, flags);
+
+	if (copy_to_user(buf, &event, event.header.size))
+		return -EFAULT;
+	return event.header.size;
+}
+
+static const struct file_operations afu_fops = {
+	.owner		= THIS_MODULE,
+	.open           = afu_open,
+	.poll		= afu_poll,
+	.read		= afu_read,
+	.release        = afu_release,
+	.unlocked_ioctl = afu_ioctl,
+	.compat_ioctl   = afu_compat_ioctl,
+	.mmap           = afu_mmap,
+};
+
+static const struct file_operations afu_master_fops = {
+	.owner		= THIS_MODULE,
+	.open           = afu_master_open,
+	.poll		= afu_poll,
+	.read		= afu_read,
+	.release        = afu_release,
+	.unlocked_ioctl = afu_ioctl,
+	.compat_ioctl   = afu_compat_ioctl,
+	.mmap           = afu_mmap,
+};
+
+
+static char *cxl_devnode(struct device *dev, umode_t *mode)
+{
+	if (CXL_DEVT_IS_CARD(dev->devt)) {
+		/*
+		 * These minor numbers will eventually be used to program the
+		 * PSL and AFUs once we have dynamic reprogramming support
+		 */
+		return NULL;
+	}
+	return kasprintf(GFP_KERNEL, "cxl/%s", dev_name(dev));
+}
+
+extern struct class *cxl_class;
+
+static int cxl_add_chardev(struct cxl_afu *afu, dev_t devt, struct cdev *cdev,
+			   struct device **chardev, char *postfix, char *desc,
+			   const struct file_operations *fops)
+{
+	struct device *dev;
+	int rc;
+
+	cdev_init(cdev, fops);
+	if ((rc = cdev_add(cdev, devt, 1))) {
+		dev_err(&afu->dev, "Unable to add %s chardev: %i\n", desc, rc);
+		return rc;
+	}
+
+	dev = device_create(cxl_class, &afu->dev, devt, afu,
+			"afu%i.%i%s", afu->adapter->adapter_num, afu->slice, postfix);
+	if (IS_ERR(dev)) {
+		dev_err(&afu->dev, "Unable to create %s chardev in sysfs: %i\n", desc, rc);
+		rc = PTR_ERR(dev);
+		goto err;
+	}
+
+	*chardev = dev;
+
+	return 0;
+err:
+	cdev_del(cdev);
+	return rc;
+}
+
+int cxl_chardev_d_afu_add(struct cxl_afu *afu)
+{
+	return cxl_add_chardev(afu, CXL_AFU_MKDEV_D(afu), &afu->afu_cdev_d,
+			       &afu->chardev_d, "d", "dedicated",
+			       &afu_master_fops); /* Uses master fops */
+}
+
+int cxl_chardev_m_afu_add(struct cxl_afu *afu)
+{
+	return cxl_add_chardev(afu, CXL_AFU_MKDEV_M(afu), &afu->afu_cdev_m,
+			       &afu->chardev_m, "m", "master",
+			       &afu_master_fops);
+}
+
+int cxl_chardev_s_afu_add(struct cxl_afu *afu)
+{
+	return cxl_add_chardev(afu, CXL_AFU_MKDEV_S(afu), &afu->afu_cdev_s,
+			       &afu->chardev_s, "s", "shared",
+			       &afu_fops);
+}
+
+void cxl_chardev_afu_remove(struct cxl_afu *afu)
+{
+	if (afu->chardev_d) {
+		cdev_del(&afu->afu_cdev_d);
+		device_unregister(afu->chardev_d);
+		afu->chardev_d = NULL;
+	}
+	if (afu->chardev_m) {
+		cdev_del(&afu->afu_cdev_m);
+		device_unregister(afu->chardev_m);
+		afu->chardev_m = NULL;
+	}
+	if (afu->chardev_s) {
+		cdev_del(&afu->afu_cdev_s);
+		device_unregister(afu->chardev_s);
+		afu->chardev_s = NULL;
+	}
+}
+
+int cxl_register_afu(struct cxl_afu *afu)
+{
+	afu->dev.class = cxl_class;
+
+	return device_register(&afu->dev);
+}
+
+int cxl_register_adapter(struct cxl *adapter)
+{
+	adapter->dev.class = cxl_class;
+
+	/*
+	 * Future: When we support dynamically reprogramming the PSL & AFU we
+	 * will expose the interface to do that via a chardev:
+	 * adapter->dev.devt = CXL_CARD_MKDEV(adapter);
+	 */
+
+	return device_register(&adapter->dev);
+}
+
+int __init cxl_file_init(void)
+{
+	int rc;
+
+	/*
+	 * If these change we really need to update API.  Either change some
+	 * flags or update API version number CXL_API_VERSION.
+	 */
+	BUILD_BUG_ON(CXL_API_VERSION != 1);
+	BUILD_BUG_ON(sizeof(struct cxl_ioctl_start_work) != 64);
+	BUILD_BUG_ON(sizeof(struct cxl_event_header) != 8);
+	BUILD_BUG_ON(sizeof(struct cxl_event_afu_interrupt) != 8);
+	BUILD_BUG_ON(sizeof(struct cxl_event_data_storage) != 32);
+	BUILD_BUG_ON(sizeof(struct cxl_event_afu_error) != 16);
+
+	if ((rc = alloc_chrdev_region(&cxl_dev, 0, CXL_NUM_MINORS, "cxl"))) {
+		pr_err("Unable to allocate CXL major number: %i\n", rc);
+		return rc;
+	}
+
+	pr_devel("CXL device allocated, MAJOR %i\n", MAJOR(cxl_dev));
+
+	cxl_class = class_create(THIS_MODULE, "cxl");
+	if (IS_ERR(cxl_class)) {
+		pr_err("Unable to create CXL class\n");
+		rc = PTR_ERR(cxl_class);
+		goto err;
+	}
+	cxl_class->devnode = cxl_devnode;
+
+	return 0;
+
+err:
+	unregister_chrdev_region(cxl_dev, CXL_NUM_MINORS);
+	return rc;
+}
+
+void cxl_file_exit(void)
+{
+	unregister_chrdev_region(cxl_dev, CXL_NUM_MINORS);
+	class_destroy(cxl_class);
+}