soc: aspeed: Add XDMA engine driver

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new file mode 100644
index 000000000000..2efaa6067c39
@@ -0,0 +1,38 @@
+/* SPDX-License-Identifier: GPL-2.0+ WITH Linux-syscall-note */
+/* Copyright IBM Corp 2019 */
+
+#ifndef _UAPI_LINUX_ASPEED_XDMA_H_
+#define _UAPI_LINUX_ASPEED_XDMA_H_
+
+#include <linux/types.h>
+
+/*
+ * aspeed_xdma_direction
+ *
+ * ASPEED_XDMA_DIRECTION_DOWNSTREAM: transfers data from the host to the BMC
+ *
+ * ASPEED_XDMA_DIRECTION_UPSTREAM: transfers data from the BMC to the host
+ */
+enum aspeed_xdma_direction {
+	ASPEED_XDMA_DIRECTION_DOWNSTREAM = 0,
+	ASPEED_XDMA_DIRECTION_UPSTREAM,
+};
+
+/*
+ * aspeed_xdma_op
+ *
+ * host_addr: the DMA address on the host side, typically configured by PCI
+ *            subsystem
+ *
+ * len: the size of the transfer in bytes
+ *
+ * direction: an enumerator indicating the direction of the DMA operation; see
+ *            enum aspeed_xdma_direction
+ */
+struct aspeed_xdma_op {
+	__u64 host_addr;
+	__u32 len;
+	__u32 direction;
+};
+
+#endif /* _UAPI_LINUX_ASPEED_XDMA_H_ */

index bc746b262de7..4fcdf0967cd4 100644
@@ -13,6 +13,7 @@
 #include <linux/io.h>
 #include <linux/jiffies.h>
 #include <linux/mfd/syscon.h>
+#include <linux/miscdevice.h>
 #include <linux/module.h>
 #include <linux/mutex.h>
 #include <linux/of_device.h>

@@ -208,6 +209,8 @@ struct aspeed_xdma {
 	struct reset_control *reset;
 	struct reset_control *reset_rc;
 
+	/* file_lock serializes reads of current_client */
+	struct mutex file_lock;
 	/* client_lock protects error and in_progress of the client */
 	spinlock_t client_lock;
 	struct aspeed_xdma_client *current_client;

@@ -230,6 +233,8 @@ struct aspeed_xdma {
 	void __iomem *mem_virt;
 	dma_addr_t cmdq_phys;
 	struct gen_pool *pool;
+
+	struct miscdevice misc;
 };
 
 struct aspeed_xdma_client {

@@ -538,6 +543,191 @@ static irqreturn_t aspeed_xdma_pcie_irq(int irq, void *arg)
 	return IRQ_HANDLED;
 }
 
+static ssize_t aspeed_xdma_write(struct file *file, const char __user *buf,
+				 size_t len, loff_t *offset)
+{
+	int rc;
+	struct aspeed_xdma_op op;
+	struct aspeed_xdma_client *client = file->private_data;
+	struct aspeed_xdma *ctx = client->ctx;
+
+	if (len != sizeof(op))
+		return -EINVAL;
+
+	rc = copy_from_user(&op, buf, len);
+	if (rc)
+		return rc;
+
+	if (!op.len || op.len > client->size ||
+	    op.direction > ASPEED_XDMA_DIRECTION_UPSTREAM)
+		return -EINVAL;
+
+	if (file->f_flags & O_NONBLOCK) {
+		if (READ_ONCE(ctx->in_reset))
+			return -EBUSY;
+
+		if (!mutex_trylock(&ctx->file_lock))
+			return -EAGAIN;
+
+		if (READ_ONCE(ctx->current_client)) {
+			mutex_unlock(&ctx->file_lock);
+			return -EBUSY;
+		}
+	} else {
+		mutex_lock(&ctx->file_lock);
+
+		rc = wait_event_interruptible(ctx->wait, !ctx->current_client);
+		if (rc) {
+			mutex_unlock(&ctx->file_lock);
+			return -EINTR;
+		}
+	}
+
+	aspeed_xdma_start(ctx, &op, client->phys, client);
+
+	mutex_unlock(&ctx->file_lock);
+
+	if (!(file->f_flags & O_NONBLOCK)) {
+		rc = wait_event_interruptible(ctx->wait, !client->in_progress);
+		if (rc)
+			return -EINTR;
+
+		if (client->error)
+			return -EIO;
+	}
+
+	return len;
+}
+
+static __poll_t aspeed_xdma_poll(struct file *file,
+				 struct poll_table_struct *wait)
+{
+	__poll_t mask = 0;
+	__poll_t req = poll_requested_events(wait);
+	struct aspeed_xdma_client *client = file->private_data;
+	struct aspeed_xdma *ctx = client->ctx;
+
+	if (req & (EPOLLIN | EPOLLRDNORM)) {
+		if (client->in_progress)
+			poll_wait(file, &ctx->wait, wait);
+
+		if (!client->in_progress) {
+			if (client->error)
+				mask |= EPOLLERR;
+			else
+				mask |= EPOLLIN | EPOLLRDNORM;
+		}
+	}
+
+	if (req & (EPOLLOUT | EPOLLWRNORM)) {
+		if (ctx->current_client)
+			poll_wait(file, &ctx->wait, wait);
+
+		if (!ctx->current_client)
+			mask |= EPOLLOUT | EPOLLWRNORM;
+	}
+
+	return mask;
+}
+
+static void aspeed_xdma_vma_close(struct vm_area_struct *vma)
+{
+	int rc;
+	struct aspeed_xdma_client *client = vma->vm_private_data;
+
+	rc = wait_event_interruptible(client->ctx->wait, !client->in_progress);
+	if (rc)
+		return;
+
+	gen_pool_free(client->ctx->pool, (unsigned long)client->virt,
+		      client->size);
+
+	client->virt = NULL;
+	client->phys = 0;
+	client->size = 0;
+}
+
+static const struct vm_operations_struct aspeed_xdma_vm_ops = {
+	.close =	aspeed_xdma_vma_close,
+};
+
+static int aspeed_xdma_mmap(struct file *file, struct vm_area_struct *vma)
+{
+	int rc;
+	struct aspeed_xdma_client *client = file->private_data;
+	struct aspeed_xdma *ctx = client->ctx;
+
+	/* restrict file to one mapping */
+	if (client->size)
+		return -EBUSY;
+
+	client->size = vma->vm_end - vma->vm_start;
+	client->virt = gen_pool_dma_alloc(ctx->pool, client->size,
+					  &client->phys);
+	if (!client->virt) {
+		client->phys = 0;
+		client->size = 0;
+		return -ENOMEM;
+	}
+
+	vma->vm_pgoff = (client->phys - ctx->mem_phys) >> PAGE_SHIFT;
+	vma->vm_ops = &aspeed_xdma_vm_ops;
+	vma->vm_private_data = client;
+	vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
+
+	rc = io_remap_pfn_range(vma, vma->vm_start, client->phys >> PAGE_SHIFT,
+				client->size, vma->vm_page_prot);
+	if (rc) {
+		dev_warn(ctx->dev, "mmap err: v[%08lx] to p[%08x], s[%08x]\n",
+			 vma->vm_start, (u32)client->phys, client->size);
+
+		gen_pool_free(ctx->pool, (unsigned long)client->virt,
+			      client->size);
+
+		client->virt = NULL;
+		client->phys = 0;
+		client->size = 0;
+		return rc;
+	}
+
+	dev_dbg(ctx->dev, "mmap: v[%08lx] to p[%08x], s[%08x]\n",
+		vma->vm_start, (u32)client->phys, client->size);
+
+	return 0;
+}
+
+static int aspeed_xdma_open(struct inode *inode, struct file *file)
+{
+	struct miscdevice *misc = file->private_data;
+	struct aspeed_xdma *ctx = container_of(misc, struct aspeed_xdma, misc);
+	struct aspeed_xdma_client *client = kzalloc(sizeof(*client),
+						    GFP_KERNEL);
+
+	if (!client)
+		return -ENOMEM;
+
+	client->ctx = ctx;
+	file->private_data = client;
+	return 0;
+}
+
+static int aspeed_xdma_release(struct inode *inode, struct file *file)
+{
+	struct aspeed_xdma_client *client = file->private_data;
+
+	kfree(client);
+	return 0;
+}
+
+static const struct file_operations aspeed_xdma_fops = {
+	.owner			= THIS_MODULE,
+	.write			= aspeed_xdma_write,
+	.poll			= aspeed_xdma_poll,
+	.mmap			= aspeed_xdma_mmap,
+	.open			= aspeed_xdma_open,
+	.release		= aspeed_xdma_release,
+};
+
 static int aspeed_xdma_init_scu(struct aspeed_xdma *ctx, struct device *dev)
 {
 	struct regmap *scu = syscon_regmap_lookup_by_phandle(dev->of_node,

@@ -610,6 +800,7 @@ static int aspeed_xdma_probe(struct platform_device *pdev)
 	ctx->chip = md;
 	ctx->dev = dev;
 	platform_set_drvdata(pdev, ctx);
+	mutex_init(&ctx->file_lock);
 	mutex_init(&ctx->start_lock);
 	INIT_WORK(&ctx->reset_work, aspeed_xdma_reset_work);
 	spin_lock_init(&ctx->client_lock);

@@ -725,6 +916,18 @@ static int aspeed_xdma_probe(struct platform_device *pdev)
 
 	aspeed_xdma_init_eng(ctx);
 
+	ctx->misc.minor = MISC_DYNAMIC_MINOR;
+	ctx->misc.fops = &aspeed_xdma_fops;
+	ctx->misc.name = "aspeed-xdma";
+	ctx->misc.parent = dev;
+	rc = misc_register(&ctx->misc);
+	if (rc) {
+		dev_err(dev, "Failed to register xdma miscdevice.\n");
+		gen_pool_free(ctx->pool, (unsigned long)ctx->cmdq,
+			      XDMA_CMDQ_SIZE);
+		goto err;
+	}
+
 	/*
 	 * This interrupt could fire immediately so only request it once the
 	 * engine and driver are initialized.

@@ -755,6 +958,7 @@ static int aspeed_xdma_remove(struct platform_device *pdev)
 {
 	struct aspeed_xdma *ctx = platform_get_drvdata(pdev);
 
+	misc_deregister(&ctx->misc);
 	gen_pool_free(ctx->pool, (unsigned long)ctx->cmdq, XDMA_CMDQ_SIZE);
 
 	reset_control_assert(ctx->reset);

index 4fcdf0967cd4..71678bff1545 100644
@@ -630,6 +630,41 @@ static __poll_t aspeed_xdma_poll(struct file *file,
 	return mask;
 }
 
+static long aspeed_xdma_ioctl(struct file *file, unsigned int cmd,
+			      unsigned long param)
+{
+	unsigned long flags;
+	struct aspeed_xdma_client *client = file->private_data;
+	struct aspeed_xdma *ctx = client->ctx;
+
+	switch (cmd) {
+	case ASPEED_XDMA_IOCTL_RESET:
+		spin_lock_irqsave(&ctx->reset_lock, flags);
+		if (ctx->in_reset) {
+			spin_unlock_irqrestore(&ctx->reset_lock, flags);
+			return 0;
+		}
+
+		ctx->in_reset = true;
+		spin_unlock_irqrestore(&ctx->reset_lock, flags);
+
+		if (ctx->current_client)
+			dev_warn(ctx->dev,
+				 "User reset with transfer in progress.\n");
+
+		mutex_lock(&ctx->start_lock);
+
+		aspeed_xdma_reset(ctx);
+
+		mutex_unlock(&ctx->start_lock);
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
 static void aspeed_xdma_vma_close(struct vm_area_struct *vma)
 {
 	int rc;

@@ -723,6 +758,7 @@ static const struct file_operations aspeed_xdma_fops = {
 	.owner			= THIS_MODULE,
 	.write			= aspeed_xdma_write,
 	.poll			= aspeed_xdma_poll,
+	.unlocked_ioctl		= aspeed_xdma_ioctl,
 	.mmap			= aspeed_xdma_mmap,
 	.open			= aspeed_xdma_open,
 	.release		= aspeed_xdma_release,

index 2efaa6067c39..3a3646fd1e9e 100644
@@ -4,8 +4,12 @@
 #ifndef _UAPI_LINUX_ASPEED_XDMA_H_
 #define _UAPI_LINUX_ASPEED_XDMA_H_
 
+#include <linux/ioctl.h>
 #include <linux/types.h>
 
+#define __ASPEED_XDMA_IOCTL_MAGIC	0xb7
+#define ASPEED_XDMA_IOCTL_RESET		_IO(__ASPEED_XDMA_IOCTL_MAGIC, 0)
+
 /*
  * aspeed_xdma_direction
  *