Re: [PATCH RFC 2/3] fpga: support loading from a pre-allocated buffer
Hi Nava,
On minor comment below.
On 02/04/2021 11.09, Nava kishore Manne wrote:
Some systems are memory constrained but they need to load very
large Configuration files. The FPGA subsystem allows drivers to
request this Configuration image be loaded from the filesystem,
but this requires that the entire configuration data be loaded
into kernel memory first before it's provided to the driver.
This can lead to a situation where we map the configuration
data twice, once to load the configuration data into kernel
memory and once to copy the configuration data into the final
resting place which is nothing but a dma-able continuous buffer.
This creates needless memory pressure and delays due to multiple
copies. Let's add a dmabuf handling support to the fpga manager
framework that allows drivers to load the Configuration data
directly from a pre-allocated buffer. This skips the intermediate
step of allocating a buffer in kernel memory to hold the
Configuration data.
Signed-off-by: Nava kishore Manne
---
drivers/fpga/fpga-mgr.c | 126 +-
drivers/fpga/of-fpga-region.c | 3 +
include/linux/fpga/fpga-mgr.h | 6 +-
3 files changed, 132 insertions(+), 3 deletions(-)
diff --git a/drivers/fpga/fpga-mgr.c b/drivers/fpga/fpga-mgr.c
index b85bc47c91a9..13faed61af62 100644
--- a/drivers/fpga/fpga-mgr.c
+++ b/drivers/fpga/fpga-mgr.c
@@ -8,6 +8,8 @@
* With code from the mailing list:
* Copyright (C) 2013 Xilinx, Inc.
*/
+#include
+#include
#include
#include
#include
@@ -306,6 +308,51 @@ static int fpga_mgr_buf_load(struct fpga_manager *mgr,
return rc;
}
+/**
+ * fpga_mgr_buf_load - load fpga from image in dma buffer
s/fpga_mgr_buf_load/fpga_dmabuf_load
// Martin
+ * @mgr:fpga manager
+ * @info: fpga image info
+ *
+ * Step the low level fpga manager through the device-specific steps of getting
+ * an FPGA ready to be configured, writing the image to it, then doing whatever
+ * post-configuration steps necessary. This code assumes the caller got the
+ * mgr pointer from of_fpga_mgr_get() and checked that it is not an error code.
+ *
+ * Return: 0 on success, negative error code otherwise.
+ */
+static int fpga_dmabuf_load(struct fpga_manager *mgr,
+ struct fpga_image_info *info)
+{
+ struct dma_buf_attachment *attach;
+ struct sg_table *sgt;
+ int ret;
+
+ /* create attachment for dmabuf with the user device */
+ attach = dma_buf_attach(mgr->dmabuf, >dev);
+ if (IS_ERR(attach)) {
+ pr_err("failed to attach dmabuf\n");
+ ret = PTR_ERR(attach);
+ goto fail_put;
+ }
+
+ sgt = dma_buf_map_attachment(attach, DMA_BIDIRECTIONAL);
+ if (IS_ERR(sgt)) {
+ ret = PTR_ERR(sgt);
+ goto fail_detach;
+ }
+
+ info->sgt = sgt;
+ ret = fpga_mgr_buf_load_sg(mgr, info, info->sgt);
+ dma_buf_unmap_attachment(attach, sgt, DMA_BIDIRECTIONAL);
+
+fail_detach:
+ dma_buf_detach(mgr->dmabuf, attach);
+fail_put:
+ dma_buf_put(mgr->dmabuf);
+
+ return ret;
+}
+
/**
* fpga_mgr_firmware_load - request firmware and load to fpga
* @mgr: fpga manager
@@ -358,6 +405,8 @@ static int fpga_mgr_firmware_load(struct fpga_manager *mgr,
*/
int fpga_mgr_load(struct fpga_manager *mgr, struct fpga_image_info *info)
{
+ if (info->flags & FPGA_MGR_CONFIG_DMA_BUF)
+ return fpga_dmabuf_load(mgr, info);
if (info->sgt)
return fpga_mgr_buf_load_sg(mgr, info, info->sgt);
if (info->buf && info->count)
@@ -549,6 +598,62 @@ void fpga_mgr_unlock(struct fpga_manager *mgr)
}
EXPORT_SYMBOL_GPL(fpga_mgr_unlock);
+static int fpga_dmabuf_fd_get(struct file *file, char __user *argp)
+{
+ struct fpga_manager *mgr = (struct fpga_manager *)(file->private_data);
+ int buffd;
+
+ if (copy_from_user(, argp, sizeof(buffd)))
+ return -EFAULT;
+
+ mgr->dmabuf = dma_buf_get(buffd);
+ if (IS_ERR_OR_NULL(mgr->dmabuf))
+ return -EINVAL;
+
+ return 0;
+}
+
+static int fpga_device_open(struct inode *inode, struct file *file)
+{
+ struct miscdevice *miscdev = file->private_data;
+ struct fpga_manager *mgr = container_of(miscdev,
+ struct fpga_manager, miscdev);
+
+ file->private_data = mgr;
+
+ return 0;
+}
+
+static int fpga_device_release(struct inode *inode, struct file *file)
+{
+ return 0;
+}
+
+static long fpga_device_ioctl(struct file *file, unsigned int cmd,
+ unsigned long arg)
+{
+ char __user *argp = (char __user *)arg;
+ int err;
+
+ switch (cmd) {
+ case FPGA_IOCTL_LOAD_DMA_BUFF:
+ err = fpga_dmabuf_fd_get(file, argp);
+ break;
+ default:
+ err = -ENOTTY;
+ }
+
+ return
[PATCH RFC 2/3] fpga: support loading from a pre-allocated buffer
Some systems are memory constrained but they need to load very
large Configuration files. The FPGA subsystem allows drivers to
request this Configuration image be loaded from the filesystem,
but this requires that the entire configuration data be loaded
into kernel memory first before it's provided to the driver.
This can lead to a situation where we map the configuration
data twice, once to load the configuration data into kernel
memory and once to copy the configuration data into the final
resting place which is nothing but a dma-able continuous buffer.
This creates needless memory pressure and delays due to multiple
copies. Let's add a dmabuf handling support to the fpga manager
framework that allows drivers to load the Configuration data
directly from a pre-allocated buffer. This skips the intermediate
step of allocating a buffer in kernel memory to hold the
Configuration data.
Signed-off-by: Nava kishore Manne
---
drivers/fpga/fpga-mgr.c | 126 +-
drivers/fpga/of-fpga-region.c | 3 +
include/linux/fpga/fpga-mgr.h | 6 +-
3 files changed, 132 insertions(+), 3 deletions(-)
diff --git a/drivers/fpga/fpga-mgr.c b/drivers/fpga/fpga-mgr.c
index b85bc47c91a9..13faed61af62 100644
--- a/drivers/fpga/fpga-mgr.c
+++ b/drivers/fpga/fpga-mgr.c
@@ -8,6 +8,8 @@
* With code from the mailing list:
* Copyright (C) 2013 Xilinx, Inc.
*/
+#include
+#include
#include
#include
#include
@@ -306,6 +308,51 @@ static int fpga_mgr_buf_load(struct fpga_manager *mgr,
return rc;
}
+/**
+ * fpga_mgr_buf_load - load fpga from image in dma buffer
+ * @mgr:fpga manager
+ * @info: fpga image info
+ *
+ * Step the low level fpga manager through the device-specific steps of getting
+ * an FPGA ready to be configured, writing the image to it, then doing whatever
+ * post-configuration steps necessary. This code assumes the caller got the
+ * mgr pointer from of_fpga_mgr_get() and checked that it is not an error code.
+ *
+ * Return: 0 on success, negative error code otherwise.
+ */
+static int fpga_dmabuf_load(struct fpga_manager *mgr,
+ struct fpga_image_info *info)
+{
+ struct dma_buf_attachment *attach;
+ struct sg_table *sgt;
+ int ret;
+
+ /* create attachment for dmabuf with the user device */
+ attach = dma_buf_attach(mgr->dmabuf, >dev);
+ if (IS_ERR(attach)) {
+ pr_err("failed to attach dmabuf\n");
+ ret = PTR_ERR(attach);
+ goto fail_put;
+ }
+
+ sgt = dma_buf_map_attachment(attach, DMA_BIDIRECTIONAL);
+ if (IS_ERR(sgt)) {
+ ret = PTR_ERR(sgt);
+ goto fail_detach;
+ }
+
+ info->sgt = sgt;
+ ret = fpga_mgr_buf_load_sg(mgr, info, info->sgt);
+ dma_buf_unmap_attachment(attach, sgt, DMA_BIDIRECTIONAL);
+
+fail_detach:
+ dma_buf_detach(mgr->dmabuf, attach);
+fail_put:
+ dma_buf_put(mgr->dmabuf);
+
+ return ret;
+}
+
/**
* fpga_mgr_firmware_load - request firmware and load to fpga
* @mgr: fpga manager
@@ -358,6 +405,8 @@ static int fpga_mgr_firmware_load(struct fpga_manager *mgr,
*/
int fpga_mgr_load(struct fpga_manager *mgr, struct fpga_image_info *info)
{
+ if (info->flags & FPGA_MGR_CONFIG_DMA_BUF)
+ return fpga_dmabuf_load(mgr, info);
if (info->sgt)
return fpga_mgr_buf_load_sg(mgr, info, info->sgt);
if (info->buf && info->count)
@@ -549,6 +598,62 @@ void fpga_mgr_unlock(struct fpga_manager *mgr)
}
EXPORT_SYMBOL_GPL(fpga_mgr_unlock);
+static int fpga_dmabuf_fd_get(struct file *file, char __user *argp)
+{
+ struct fpga_manager *mgr = (struct fpga_manager *)(file->private_data);
+ int buffd;
+
+ if (copy_from_user(, argp, sizeof(buffd)))
+ return -EFAULT;
+
+ mgr->dmabuf = dma_buf_get(buffd);
+ if (IS_ERR_OR_NULL(mgr->dmabuf))
+ return -EINVAL;
+
+ return 0;
+}
+
+static int fpga_device_open(struct inode *inode, struct file *file)
+{
+ struct miscdevice *miscdev = file->private_data;
+ struct fpga_manager *mgr = container_of(miscdev,
+ struct fpga_manager, miscdev);
+
+ file->private_data = mgr;
+
+ return 0;
+}
+
+static int fpga_device_release(struct inode *inode, struct file *file)
+{
+ return 0;
+}
+
+static long fpga_device_ioctl(struct file *file, unsigned int cmd,
+ unsigned long arg)
+{
+ char __user *argp = (char __user *)arg;
+ int err;
+
+ switch (cmd) {
+ case FPGA_IOCTL_LOAD_DMA_BUFF:
+ err = fpga_dmabuf_fd_get(file, argp);
+ break;
+ default:
+ err = -ENOTTY;
+ }
+
+ return err;
+}
+
+static const struct file_operations fpga_fops = {
+ .owner = THIS_MODULE,
+ .open = fpga_device_open,
+
