[PATCH linux dev-6.12 v2 2/6] soc: aspeed: xdma: Add user interface
Ninad Palsule
ninad at linux.ibm.com
Thu Sep 4 01:58:04 AEST 2025
From: Eddie James <eajames at linux.ibm.com>
This commits adds a miscdevice to provide a user interface to the XDMA
engine. The interface provides the write operation to start DMA
operations. The DMA parameters are passed as the data to the write call.
The actual data to transfer is NOT passed through write. Note that both
directions of DMA operation are accomplished through the write command;
BMC to host and host to BMC.
The XDMA driver reserves an area of physical memory for DMA operations,
as the XDMA engine is restricted to accessing certain physical memory
areas on some platforms. This memory forms a pool from which users can
allocate pages for their usage with calls to mmap. The space allocated
by a client will be the space used in the DMA operation. For an
"upstream" (BMC to host) operation, the data in the client's area will
be transferred to the host. For a "downstream" (host to BMC) operation,
the host data will be placed in the client's memory area.
Poll is also provided in order to determine when the DMA operation is
complete for non-blocking IO.
Signed-off-by: Eddie James <eajames at linux.ibm.com>
Reviewed-by: Andrew Jeffery <andrew at aj.id.au>
Reviewed-by: Joel Stanley <joel at jms.id.au>
Link: https://lore.kernel.org/r/1588697905-23444-4-git-send-email-eajames@linux.ibm.com
Signed-off-by: Joel Stanley <joel at jms.id.au>
Signed-off-by: Ninad Palsule <ninad at linux.ibm.com>
---
drivers/soc/aspeed/aspeed-xdma.c | 264 +++++++++++++++++++++++++++++++
1 file changed, 264 insertions(+)
diff --git a/drivers/soc/aspeed/aspeed-xdma.c b/drivers/soc/aspeed/aspeed-xdma.c
index 947e19323a1b5..d1b0a047c8798 100644
--- a/drivers/soc/aspeed/aspeed-xdma.c
+++ b/drivers/soc/aspeed/aspeed-xdma.c
@@ -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>
@@ -238,6 +239,8 @@ struct aspeed_xdma {
dma_addr_t mem_coherent;
dma_addr_t cmdq_phys;
struct gen_pool *pool;
+
+ struct miscdevice misc;
};
struct aspeed_xdma_client {
@@ -421,6 +424,50 @@ static unsigned int aspeed_xdma_ast2600_set_cmd(struct aspeed_xdma *ctx,
return rc;
}
+static int aspeed_xdma_start(struct aspeed_xdma *ctx, unsigned int num_cmds,
+ struct aspeed_xdma_cmd cmds[2], bool upstream,
+ struct aspeed_xdma_client *client)
+{
+ unsigned int i;
+ int rc = -EBUSY;
+ unsigned long flags;
+
+ spin_lock_irqsave(&ctx->engine_lock, flags);
+ if (ctx->in_reset)
+ goto unlock;
+
+ spin_lock(&ctx->client_lock);
+ if (ctx->current_client) {
+ spin_unlock(&ctx->client_lock);
+ goto unlock;
+ }
+
+ client->error = false;
+ client->in_progress = true;
+ ctx->current_client = client;
+ spin_unlock(&ctx->client_lock);
+
+ ctx->upstream = upstream;
+ for (i = 0; i < num_cmds; ++i) {
+ /*
+ * Use memcpy_toio here to get some barriers before starting
+ * the operation. The command(s) need to be in physical memory
+ * before the XDMA engine starts.
+ */
+ memcpy_toio(&ctx->cmdq[ctx->cmd_idx], &cmds[i],
+ sizeof(struct aspeed_xdma_cmd));
+ ctx->cmd_idx = (ctx->cmd_idx + 1) % XDMA_NUM_CMDS;
+ }
+
+ aspeed_xdma_writel(ctx, ctx->chip->regs.bmc_cmdq_writep,
+ ctx->cmd_idx * ctx->chip->queue_entry_size);
+ rc = 0;
+
+unlock:
+ spin_unlock_irqrestore(&ctx->engine_lock, flags);
+ return rc;
+}
+
static void aspeed_xdma_done(struct aspeed_xdma *ctx, bool error)
{
unsigned long flags;
@@ -513,6 +560,210 @@ 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;
+ unsigned int num_cmds;
+ struct aspeed_xdma_op op;
+ struct aspeed_xdma_cmd cmds[2];
+ struct aspeed_xdma_client *client = file->private_data;
+ struct aspeed_xdma *ctx = client->ctx;
+
+ if (len != sizeof(op))
+ return -EINVAL;
+
+ if (copy_from_user(&op, buf, len))
+ return -EFAULT;
+
+ if (!op.len || op.len > client->size ||
+ op.direction > ASPEED_XDMA_DIRECTION_UPSTREAM)
+ return -EINVAL;
+
+ num_cmds = ctx->chip->set_cmd(ctx, cmds, &op, client->phys);
+ do {
+ rc = aspeed_xdma_start(ctx, num_cmds, cmds, !!op.direction,
+ client);
+ if (!rc)
+ break;
+
+ if ((file->f_flags & O_NONBLOCK) || rc != -EBUSY)
+ return rc;
+
+ rc = wait_event_interruptible(ctx->wait,
+ !(ctx->current_client ||
+ ctx->in_reset));
+ } while (!rc);
+
+ if (rc)
+ return -EINTR;
+
+ 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 (READ_ONCE(client->in_progress))
+ poll_wait(file, &ctx->wait, wait);
+
+ if (!READ_ONCE(client->in_progress)) {
+ if (READ_ONCE(client->error))
+ mask |= EPOLLERR;
+ else
+ mask |= EPOLLIN | EPOLLRDNORM;
+ }
+ }
+
+ if (req & (EPOLLOUT | EPOLLWRNORM)) {
+ if (READ_ONCE(ctx->current_client))
+ poll_wait(file, &ctx->wait, wait);
+
+ if (!READ_ONCE(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;
+
+ kobject_get(&ctx->kobj);
+ client->ctx = ctx;
+ file->private_data = client;
+ return 0;
+}
+
+static int aspeed_xdma_release(struct inode *inode, struct file *file)
+{
+ bool reset = false;
+ unsigned long flags;
+ struct aspeed_xdma_client *client = file->private_data;
+ struct aspeed_xdma *ctx = client->ctx;
+
+ spin_lock_irqsave(&ctx->client_lock, flags);
+ if (client == ctx->current_client) {
+ spin_lock(&ctx->engine_lock);
+ if (ctx->in_reset) {
+ ctx->current_client = NULL;
+ } else {
+ ctx->in_reset = true;
+ reset = true;
+ }
+ spin_unlock(&ctx->engine_lock);
+ }
+ spin_unlock_irqrestore(&ctx->client_lock, flags);
+
+ if (reset)
+ aspeed_xdma_reset(ctx);
+
+ if (client->virt)
+ gen_pool_free(ctx->pool, (unsigned long)client->virt,
+ client->size);
+
+ kfree(client);
+ kobject_put(&ctx->kobj);
+ 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,
@@ -779,6 +1030,16 @@ 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");
+ goto err_misc;
+ }
+
/*
* This interrupt could fire immediately so only request it once the
* engine and driver are initialized.
@@ -798,6 +1059,8 @@ static int aspeed_xdma_probe(struct platform_device *pdev)
kobject_init(&ctx->kobj, &aspeed_xdma_kobject_type);
return 0;
+err_misc:
+ gen_pool_free(ctx->pool, (unsigned long)ctx->cmdq, XDMA_CMDQ_SIZE);
err_pool:
reset_control_assert(ctx->reset);
err_reset:
@@ -837,6 +1100,7 @@ static void aspeed_xdma_remove(struct platform_device *pdev)
aspeed_xdma_done(ctx, true);
+ misc_deregister(&ctx->misc);
kobject_put(&ctx->kobj);
}
--
2.48.1
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