dmaengine: ptdma: register PTDMA controller as a DMA resource

Register ptdma queue to Linux dmaengine framework as general-purpose
DMA channels.

Signed-off-by: Sanjay R Mehta <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Vinod Koul <[e-mail]>

drivers/dma/ptdma/Kconfig

···
 config AMD_PTDMA
 	tristate  "AMD PassThru DMA Engine"
 	depends on X86_64 && PCI
+	select DMA_ENGINE
+	select DMA_VIRTUAL_CHANNELS
 	help
 	  Enable support for the AMD PTDMA controller. This controller
 	  provides DMA capabilities to perform high bandwidth memory to

drivers/dma/ptdma/Makefile

···
 
 obj-$(CONFIG_AMD_PTDMA) += ptdma.o
 
-ptdma-objs := ptdma-dev.o
+ptdma-objs := ptdma-dev.o ptdma-dmaengine.o
 
 ptdma-$(CONFIG_PCI) += ptdma-pci.o

drivers/dma/ptdma/ptdma-dev.c

···
 	iowrite32(SUPPORTED_INTERRUPTS, pt->cmd_q.reg_control + 0x000C);
 }
 
+static void pt_do_cmd_complete(unsigned long data)
+{
+	struct pt_tasklet_data *tdata = (struct pt_tasklet_data *)data;
+	struct pt_cmd *cmd = tdata->cmd;
+	struct pt_cmd_queue *cmd_q = &cmd->pt->cmd_q;
+	u32 tail;
+
+	if (cmd_q->cmd_error) {
+	       /*
+		* Log the error and flush the queue by
+		* moving the head pointer
+		*/
+		tail = lower_32_bits(cmd_q->qdma_tail + cmd_q->qidx * Q_DESC_SIZE);
+		pt_log_error(cmd_q->pt, cmd_q->cmd_error);
+		iowrite32(tail, cmd_q->reg_control + 0x0008);
+	}
+
+	cmd->pt_cmd_callback(cmd->data, cmd->ret);
+}
+
 static irqreturn_t pt_core_irq_handler(int irq, void *data)
 {
 	struct pt_device *pt = data;
···
 		/* Acknowledge the interrupt */
 		iowrite32(status, cmd_q->reg_control + 0x0010);
 		pt_core_enable_queue_interrupts(pt);
+		pt_do_cmd_complete((ulong)&pt->tdata);
 	}
 	return IRQ_HANDLED;
 }
···
 
 	pt_core_enable_queue_interrupts(pt);
 
+	/* Register the DMA engine support */
+	ret = pt_dmaengine_register(pt);
+	if (ret)
+		goto e_dmaengine;
+
 	return 0;
+
+e_dmaengine:
+	free_irq(pt->pt_irq, pt);
 
 e_dma_alloc:
 	dma_free_coherent(dev, cmd_q->qsize, cmd_q->qbase, cmd_q->qbase_dma);
···
 	struct device *dev = pt->dev;
 	struct pt_cmd_queue *cmd_q = &pt->cmd_q;
 	struct pt_cmd *cmd;
+
+	/* Unregister the DMA engine */
+	pt_dmaengine_unregister(pt);
 
 	/* Disable and clear interrupts */
 	pt_core_disable_queue_interrupts(pt);

drivers/dma/ptdma/ptdma-dmaengine.c

···
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * AMD Passthrough DMA device driver
+ * -- Based on the CCP driver
+ *
+ * Copyright (C) 2016,2021 Advanced Micro Devices, Inc.
+ *
+ * Author: Sanjay R Mehta <[e-mail]>
+ * Author: Gary R Hook <[e-mail]>
+ */
+
+#include "ptdma.h"
+#include "../dmaengine.h"
+#include "../virt-dma.h"
+
+static inline struct pt_dma_chan *to_pt_chan(struct dma_chan *dma_chan)
+{
+	return container_of(dma_chan, struct pt_dma_chan, vc.chan);
+}
+
+static inline struct pt_dma_desc *to_pt_desc(struct virt_dma_desc *vd)
+{
+	return container_of(vd, struct pt_dma_desc, vd);
+}
+
+static void pt_free_chan_resources(struct dma_chan *dma_chan)
+{
+	struct pt_dma_chan *chan = to_pt_chan(dma_chan);
+
+	vchan_free_chan_resources(&chan->vc);
+}
+
+static void pt_synchronize(struct dma_chan *dma_chan)
+{
+	struct pt_dma_chan *chan = to_pt_chan(dma_chan);
+
+	vchan_synchronize(&chan->vc);
+}
+
+static void pt_do_cleanup(struct virt_dma_desc *vd)
+{
+	struct pt_dma_desc *desc = to_pt_desc(vd);
+	struct pt_device *pt = desc->pt;
+
+	kmem_cache_free(pt->dma_desc_cache, desc);
+}
+
+static int pt_dma_start_desc(struct pt_dma_desc *desc)
+{
+	struct pt_passthru_engine *pt_engine;
+	struct pt_device *pt;
+	struct pt_cmd *pt_cmd;
+	struct pt_cmd_queue *cmd_q;
+
+	desc->issued_to_hw = 1;
+
+	pt_cmd = &desc->pt_cmd;
+	pt = pt_cmd->pt;
+	cmd_q = &pt->cmd_q;
+	pt_engine = &pt_cmd->passthru;
+
+	pt->tdata.cmd = pt_cmd;
+
+	/* Execute the command */
+	pt_cmd->ret = pt_core_perform_passthru(cmd_q, pt_engine);
+
+	return 0;
+}
+
+static struct pt_dma_desc *pt_next_dma_desc(struct pt_dma_chan *chan)
+{
+	/* Get the next DMA descriptor on the active list */
+	struct virt_dma_desc *vd = vchan_next_desc(&chan->vc);
+
+	return vd ? to_pt_desc(vd) : NULL;
+}
+
+static struct pt_dma_desc *pt_handle_active_desc(struct pt_dma_chan *chan,
+						 struct pt_dma_desc *desc)
+{
+	struct dma_async_tx_descriptor *tx_desc;
+	struct virt_dma_desc *vd;
+	unsigned long flags;
+
+	/* Loop over descriptors until one is found with commands */
+	do {
+		if (desc) {
+			if (!desc->issued_to_hw) {
+				/* No errors, keep going */
+				if (desc->status != DMA_ERROR)
+					return desc;
+			}
+
+			tx_desc = &desc->vd.tx;
+			vd = &desc->vd;
+		} else {
+			tx_desc = NULL;
+		}
+
+		spin_lock_irqsave(&chan->vc.lock, flags);
+
+		if (desc) {
+			if (desc->status != DMA_ERROR)
+				desc->status = DMA_COMPLETE;
+
+			dma_cookie_complete(tx_desc);
+			dma_descriptor_unmap(tx_desc);
+			list_del(&desc->vd.node);
+		}
+
+		desc = pt_next_dma_desc(chan);
+
+		spin_unlock_irqrestore(&chan->vc.lock, flags);
+
+		if (tx_desc) {
+			dmaengine_desc_get_callback_invoke(tx_desc, NULL);
+			dma_run_dependencies(tx_desc);
+			vchan_vdesc_fini(vd);
+		}
+	} while (desc);
+
+	return NULL;
+}
+
+static void pt_cmd_callback(void *data, int err)
+{
+	struct pt_dma_desc *desc = data;
+	struct dma_chan *dma_chan;
+	struct pt_dma_chan *chan;
+	int ret;
+
+	if (err == -EINPROGRESS)
+		return;
+
+	dma_chan = desc->vd.tx.chan;
+	chan = to_pt_chan(dma_chan);
+
+	if (err)
+		desc->status = DMA_ERROR;
+
+	while (true) {
+		/* Check for DMA descriptor completion */
+		desc = pt_handle_active_desc(chan, desc);
+
+		/* Don't submit cmd if no descriptor or DMA is paused */
+		if (!desc)
+			break;
+
+		ret = pt_dma_start_desc(desc);
+		if (!ret)
+			break;
+
+		desc->status = DMA_ERROR;
+	}
+}
+
+static struct pt_dma_desc *pt_alloc_dma_desc(struct pt_dma_chan *chan,
+					     unsigned long flags)
+{
+	struct pt_dma_desc *desc;
+
+	desc = kmem_cache_zalloc(chan->pt->dma_desc_cache, GFP_NOWAIT);
+	if (!desc)
+		return NULL;
+
+	vchan_tx_prep(&chan->vc, &desc->vd, flags);
+
+	desc->pt = chan->pt;
+	desc->issued_to_hw = 0;
+	desc->status = DMA_IN_PROGRESS;
+
+	return desc;
+}
+
+static struct pt_dma_desc *pt_create_desc(struct dma_chan *dma_chan,
+					  dma_addr_t dst,
+					  dma_addr_t src,
+					  unsigned int len,
+					  unsigned long flags)
+{
+	struct pt_dma_chan *chan = to_pt_chan(dma_chan);
+	struct pt_passthru_engine *pt_engine;
+	struct pt_dma_desc *desc;
+	struct pt_cmd *pt_cmd;
+
+	desc = pt_alloc_dma_desc(chan, flags);
+	if (!desc)
+		return NULL;
+
+	pt_cmd = &desc->pt_cmd;
+	pt_cmd->pt = chan->pt;
+	pt_engine = &pt_cmd->passthru;
+	pt_cmd->engine = PT_ENGINE_PASSTHRU;
+	pt_engine->src_dma = src;
+	pt_engine->dst_dma = dst;
+	pt_engine->src_len = len;
+	pt_cmd->pt_cmd_callback = pt_cmd_callback;
+	pt_cmd->data = desc;
+
+	desc->len = len;
+
+	return desc;
+}
+
+static struct dma_async_tx_descriptor *
+pt_prep_dma_memcpy(struct dma_chan *dma_chan, dma_addr_t dst,
+		   dma_addr_t src, size_t len, unsigned long flags)
+{
+	struct pt_dma_desc *desc;
+
+	desc = pt_create_desc(dma_chan, dst, src, len, flags);
+	if (!desc)
+		return NULL;
+
+	return &desc->vd.tx;
+}
+
+static struct dma_async_tx_descriptor *
+pt_prep_dma_interrupt(struct dma_chan *dma_chan, unsigned long flags)
+{
+	struct pt_dma_chan *chan = to_pt_chan(dma_chan);
+	struct pt_dma_desc *desc;
+
+	desc = pt_alloc_dma_desc(chan, flags);
+	if (!desc)
+		return NULL;
+
+	return &desc->vd.tx;
+}
+
+static void pt_issue_pending(struct dma_chan *dma_chan)
+{
+	struct pt_dma_chan *chan = to_pt_chan(dma_chan);
+	struct pt_dma_desc *desc;
+	unsigned long flags;
+
+	spin_lock_irqsave(&chan->vc.lock, flags);
+
+	vchan_issue_pending(&chan->vc);
+
+	desc = pt_next_dma_desc(chan);
+
+	spin_unlock_irqrestore(&chan->vc.lock, flags);
+
+	/* If there was nothing active, start processing */
+	if (desc)
+		pt_cmd_callback(desc, 0);
+}
+
+static int pt_pause(struct dma_chan *dma_chan)
+{
+	struct pt_dma_chan *chan = to_pt_chan(dma_chan);
+	unsigned long flags;
+
+	spin_lock_irqsave(&chan->vc.lock, flags);
+	pt_stop_queue(&chan->pt->cmd_q);
+	spin_unlock_irqrestore(&chan->vc.lock, flags);
+
+	return 0;
+}
+
+static int pt_resume(struct dma_chan *dma_chan)
+{
+	struct pt_dma_chan *chan = to_pt_chan(dma_chan);
+	struct pt_dma_desc *desc = NULL;
+	unsigned long flags;
+
+	spin_lock_irqsave(&chan->vc.lock, flags);
+	pt_start_queue(&chan->pt->cmd_q);
+	desc = pt_next_dma_desc(chan);
+	spin_unlock_irqrestore(&chan->vc.lock, flags);
+
+	/* If there was something active, re-start */
+	if (desc)
+		pt_cmd_callback(desc, 0);
+
+	return 0;
+}
+
+static int pt_terminate_all(struct dma_chan *dma_chan)
+{
+	struct pt_dma_chan *chan = to_pt_chan(dma_chan);
+	unsigned long flags;
+	LIST_HEAD(head);
+
+	spin_lock_irqsave(&chan->vc.lock, flags);
+	vchan_get_all_descriptors(&chan->vc, &head);
+	spin_unlock_irqrestore(&chan->vc.lock, flags);
+
+	vchan_dma_desc_free_list(&chan->vc, &head);
+	vchan_free_chan_resources(&chan->vc);
+
+	return 0;
+}
+
+int pt_dmaengine_register(struct pt_device *pt)
+{
+	struct pt_dma_chan *chan;
+	struct dma_device *dma_dev = &pt->dma_dev;
+	char *cmd_cache_name;
+	char *desc_cache_name;
+	int ret;
+
+	pt->pt_dma_chan = devm_kzalloc(pt->dev, sizeof(*pt->pt_dma_chan),
+				       GFP_KERNEL);
+	if (!pt->pt_dma_chan)
+		return -ENOMEM;
+
+	cmd_cache_name = devm_kasprintf(pt->dev, GFP_KERNEL,
+					"%s-dmaengine-cmd-cache",
+					dev_name(pt->dev));
+	if (!cmd_cache_name)
+		return -ENOMEM;
+
+	desc_cache_name = devm_kasprintf(pt->dev, GFP_KERNEL,
+					 "%s-dmaengine-desc-cache",
+					 dev_name(pt->dev));
+	if (!desc_cache_name) {
+		ret = -ENOMEM;
+		goto err_cache;
+	}
+
+	pt->dma_desc_cache = kmem_cache_create(desc_cache_name,
+					       sizeof(struct pt_dma_desc), 0,
+					       SLAB_HWCACHE_ALIGN, NULL);
+	if (!pt->dma_desc_cache) {
+		ret = -ENOMEM;
+		goto err_cache;
+	}
+
+	dma_dev->dev = pt->dev;
+	dma_dev->src_addr_widths = DMA_SLAVE_BUSWIDTH_64_BYTES;
+	dma_dev->dst_addr_widths = DMA_SLAVE_BUSWIDTH_64_BYTES;
+	dma_dev->directions = DMA_MEM_TO_MEM;
+	dma_dev->residue_granularity = DMA_RESIDUE_GRANULARITY_DESCRIPTOR;
+	dma_cap_set(DMA_MEMCPY, dma_dev->cap_mask);
+	dma_cap_set(DMA_INTERRUPT, dma_dev->cap_mask);
+
+	/*
+	 * PTDMA is intended to be used with the AMD NTB devices, hence
+	 * marking it as DMA_PRIVATE.
+	 */
+	dma_cap_set(DMA_PRIVATE, dma_dev->cap_mask);
+
+	INIT_LIST_HEAD(&dma_dev->channels);
+
+	chan = pt->pt_dma_chan;
+	chan->pt = pt;
+
+	/* Set base and prep routines */
+	dma_dev->device_free_chan_resources = pt_free_chan_resources;
+	dma_dev->device_prep_dma_memcpy = pt_prep_dma_memcpy;
+	dma_dev->device_prep_dma_interrupt = pt_prep_dma_interrupt;
+	dma_dev->device_issue_pending = pt_issue_pending;
+	dma_dev->device_tx_status = dma_cookie_status;
+	dma_dev->device_pause = pt_pause;
+	dma_dev->device_resume = pt_resume;
+	dma_dev->device_terminate_all = pt_terminate_all;
+	dma_dev->device_synchronize = pt_synchronize;
+
+	chan->vc.desc_free = pt_do_cleanup;
+	vchan_init(&chan->vc, dma_dev);
+
+	dma_set_mask_and_coherent(pt->dev, DMA_BIT_MASK(64));
+
+	ret = dma_async_device_register(dma_dev);
+	if (ret)
+		goto err_reg;
+
+	return 0;
+
+err_reg:
+	kmem_cache_destroy(pt->dma_desc_cache);
+
+err_cache:
+	kmem_cache_destroy(pt->dma_cmd_cache);
+
+	return ret;
+}
+
+void pt_dmaengine_unregister(struct pt_device *pt)
+{
+	struct dma_device *dma_dev = &pt->dma_dev;
+
+	dma_async_device_unregister(dma_dev);
+
+	kmem_cache_destroy(pt->dma_desc_cache);
+	kmem_cache_destroy(pt->dma_cmd_cache);
+}

drivers/dma/ptdma/ptdma.h

···
 #define __PT_DEV_H__
 
 #include <linux/device.h>
+#include <linux/dmaengine.h>
 #include <linux/pci.h>
 #include <linux/spinlock.h>
 #include <linux/mutex.h>
 #include <linux/list.h>
 #include <linux/wait.h>
 #include <linux/dmapool.h>
+
+#include "../virt-dma.h"
 
 #define MAX_PT_NAME_LEN			16
 #define MAX_DMAPOOL_NAME_LEN		32
···
 	void *data;
 };
 
+struct pt_dma_desc {
+	struct virt_dma_desc vd;
+	struct pt_device *pt;
+	enum dma_status status;
+	size_t len;
+	bool issued_to_hw;
+	struct pt_cmd pt_cmd;
+};
+
+struct pt_dma_chan {
+	struct virt_dma_chan vc;
+	struct pt_device *pt;
+};
+
 struct pt_cmd_queue {
 	struct pt_device *pt;
 
···
 	 */
 	struct pt_cmd_queue cmd_q;
 
+	/* Support for the DMA Engine capabilities */
+	struct dma_device dma_dev;
+	struct pt_dma_chan *pt_dma_chan;
+	struct kmem_cache *dma_cmd_cache;
+	struct kmem_cache *dma_desc_cache;
+
 	wait_queue_head_t lsb_queue;
 
 	struct pt_tasklet_data tdata;
···
 struct pt_dev_vdata {
 	const unsigned int bar;
 };
+
+int pt_dmaengine_register(struct pt_device *pt);
+void pt_dmaengine_unregister(struct pt_device *pt);
 
 int pt_core_init(struct pt_device *pt);
 void pt_core_destroy(struct pt_device *pt);