RE: [RFC] fpga: dfl: a prototype uio driver

[Wu, Hao]

> Subject: Re: [RFC] fpga: dfl: a prototype uio driver
> 
> On Sun, Dec 06, 2020 at 01:55:54PM -0800, trix@xxxxxxxxxx wrote:
> > From: Tom Rix <trix@xxxxxxxxxx>
> >
> > >From [PATCH 0/2] UIO support for dfl devices
> > https://lore.kernel.org/linux-fpga/1602828151-24784-1-git-send-email-
> yilun.xu@xxxxxxxxx/
> >
> > Here is an idea to have uio support with no driver override.
> >
> > This makes UIO the primary driver interface because every feature
> > will have one and makes the existing platform driver interface
> > secondary.  There will be a new burden for locking write access when
> > they compete.
> >
> > Example shows finding the fpga's temperture.
> 
> Hi Tom:
> 
> Thanks for the idea and detailed illustrate with the patch. I see it
> abandons the driver_override and expose all the DFL devices to userspace
> by UIO. I'd like to see if we could get some more comments on it.

This allows concurrent access from both userspace and kernel space driver
to the same feature device? conflicts?

Hao

> 
> Thanks,
> Yilun
> 
> >
> > Signed-off-by: Tom Rix <trix@xxxxxxxxxx>
> > ---
> >  drivers/fpga/dfl-fme-main.c |  9 +++-
> >  drivers/fpga/dfl-uio.c      | 96 +++++++++++++++++++++++++++++++++++++
> >  drivers/fpga/dfl.c          | 44 ++++++++++++++++-
> >  drivers/fpga/dfl.h          |  9 ++++
> >  uio.c                       | 56 ++++++++++++++++++++++
> >  5 files changed, 212 insertions(+), 2 deletions(-)
> >  create mode 100644 drivers/fpga/dfl-uio.c
> >  create mode 100644 uio.c
> >
> > diff --git a/drivers/fpga/dfl-fme-main.c b/drivers/fpga/dfl-fme-main.c
> > index 037dc4f946f0..3323e90a18c4 100644
> > --- a/drivers/fpga/dfl-fme-main.c
> > +++ b/drivers/fpga/dfl-fme-main.c
> > @@ -709,12 +709,18 @@ static int fme_probe(struct platform_device
> *pdev)
> >  	if (ret)
> >  		goto dev_destroy;
> >
> > -	ret = dfl_fpga_dev_ops_register(pdev, &fme_fops, THIS_MODULE);
> > +	ret = dfl_fpga_dev_feature_init_uio(pdev, DFH_TYPE_FIU);
> >  	if (ret)
> >  		goto feature_uinit;
> >
> > +	ret = dfl_fpga_dev_ops_register(pdev, &fme_fops, THIS_MODULE);
> > +	if (ret)
> > +		goto feature_uinit_uio;
> > +
> >  	return 0;
> >
> > +feature_uinit_uio:
> > +	dfl_fpga_dev_feature_uinit_uio(pdev, DFH_TYPE_FIU);
> >  feature_uinit:
> >  	dfl_fpga_dev_feature_uinit(pdev);
> >  dev_destroy:
> > @@ -726,6 +732,7 @@ exit:
> >  static int fme_remove(struct platform_device *pdev)
> >  {
> >  	dfl_fpga_dev_ops_unregister(pdev);
> > +	dfl_fpga_dev_feature_uinit_uio(pdev, DFH_TYPE_FIU);
> >  	dfl_fpga_dev_feature_uinit(pdev);
> >  	fme_dev_destroy(pdev);
> >
> > diff --git a/drivers/fpga/dfl-uio.c b/drivers/fpga/dfl-uio.c
> > new file mode 100644
> > index 000000000000..7610ee0b19dc
> > --- /dev/null
> > +++ b/drivers/fpga/dfl-uio.c
> > @@ -0,0 +1,96 @@
> > +/* SPDX-License-Identifier: GPL-2.0 */
> > +/*
> > + * prototype dfl uio driver
> > + *
> > + * Copyright Tom Rix 2020
> > + */
> > +#include <linux/module.h>
> > +#include "dfl.h"
> > +
> > +static irqreturn_t dfl_uio_handler(int irq, struct uio_info *info)
> > +{
> > +	return IRQ_HANDLED;
> > +}
> > +
> > +static int dfl_uio_mmap(struct uio_info *info, struct vm_area_struct *vma)
> > +{
> > +	int ret = -ENODEV;
> > +	return ret;
> > +}
> > +
> > +static int dfl_uio_open(struct uio_info *info, struct inode *inode)
> > +{
> > +	int ret = -ENODEV;
> > +	struct dfl_feature *feature = container_of(info, struct dfl_feature,
> uio);
> > +	if (feature->dev)
> > +		mutex_lock(&feature->lock);
> > +
> > +	ret = 0;
> > +	return ret;
> > +}
> > +
> > +static int dfl_uio_release(struct uio_info *info, struct inode *inode)
> > +{
> > +	int ret = -ENODEV;
> > +	struct dfl_feature *feature = container_of(info, struct dfl_feature,
> uio);
> > +	if (feature->dev)
> > +		mutex_unlock(&feature->lock);
> > +
> > +	ret = 0;
> > +	return ret;
> > +}
> > +
> > +static int dfl_uio_irqcontrol(struct uio_info *info, s32 irq_on)
> > +{
> > +	int ret = -ENODEV;
> > +	return ret;
> > +}
> > +
> > +int dfl_uio_add(struct dfl_feature *feature)
> > +{
> > +	struct uio_info *uio = &feature->uio;
> > +	struct resource *res =
> > +		&feature->dev->resource[feature->resource_index];
> > +	int ret = 0;
> > +
> > +	uio->name = kasprintf(GFP_KERNEL, "dfl-uio-%llx", feature->id);
> > +	if (!uio->name) {
> > +		ret = -ENOMEM;
> > +		goto exit;
> > +	}
> > +
> > +	uio->version = "0.1";
> > +	uio->mem[0].memtype = UIO_MEM_PHYS;
> > +	uio->mem[0].addr = res->start & PAGE_MASK;
> > +	uio->mem[0].offs = res->start & ~PAGE_MASK;
> > +	uio->mem[0].size = (uio->mem[0].offs + resource_size(res)
> > +			    + PAGE_SIZE - 1) & PAGE_MASK;
> > +	/* How are nr_irqs > 1 handled ??? */
> > +	if (feature->nr_irqs == 1)
> > +		uio->irq = feature->irq_ctx[0].irq;
> > +	uio->handler = dfl_uio_handler;
> > +	//uio->mmap = dfl_uio_mmap;
> > +	uio->open = dfl_uio_open;
> > +	uio->release = dfl_uio_release;
> > +	uio->irqcontrol = dfl_uio_irqcontrol;
> > +
> > +	ret = uio_register_device(&feature->dev->dev, uio);
> > +	if (ret)
> > +		goto err_register;
> > +
> > +exit:
> > +	return ret;
> > +err_register:
> > +	kfree(uio->name);
> > +	goto exit;
> > +}
> > +EXPORT_SYMBOL_GPL(dfl_uio_add);
> > +
> > +int dfl_uio_remove(struct dfl_feature *feature)
> > +{
> > +	uio_unregister_device(&feature->uio);
> > +	kfree(feature->uio.name);
> > +	return 0;
> > +}
> > +EXPORT_SYMBOL_GPL(dfl_uio_remove);
> > +
> > diff --git a/drivers/fpga/dfl.c b/drivers/fpga/dfl.c
> > index 1305be48037d..af2cd3d1b5f6 100644
> > --- a/drivers/fpga/dfl.c
> > +++ b/drivers/fpga/dfl.c
> > @@ -603,6 +603,7 @@ static int dfl_feature_instance_init(struct
> platform_device *pdev,
> >  	}
> >
> >  	feature->ops = drv->ops;
> > +	mutex_init(&feature->lock);
> >
> >  	return ret;
> >  }
> > @@ -663,10 +664,51 @@ exit:
> >  }
> >  EXPORT_SYMBOL_GPL(dfl_fpga_dev_feature_init);
> >
> > +int dfl_fpga_dev_feature_init_uio(struct platform_device *pdev, int
> dfh_type) {
> > +	struct dfl_feature_platform_data *pdata = dev_get_platdata(&pdev-
> >dev);
> > +	struct dfl_feature *feature;
> > +	int ret;
> > +
> > +	dfl_fpga_dev_for_each_feature(pdata, feature) {
> > +		if (dfh_type == DFH_TYPE_FIU) {
> > +			if (feature->id == FEATURE_ID_FIU_HEADER ||
> > +			    feature->id == FEATURE_ID_AFU)
> > +			    continue;
> > +
> > +			ret = dfl_uio_add(feature);
> > +			if (ret)
> > +				goto exit;
> > +		}
> > +	}
> > +
> > +	return 0;
> > +exit:
> > +	dfl_fpga_dev_feature_uinit_uio(pdev, dfh_type);
> > +	return ret;
> > +}
> > +EXPORT_SYMBOL_GPL(dfl_fpga_dev_feature_init_uio);
> > +
> > +int dfl_fpga_dev_feature_uinit_uio(struct platform_device *pdev, int
> dfh_type) {
> > +	struct dfl_feature_platform_data *pdata = dev_get_platdata(&pdev-
> >dev);
> > +	struct dfl_feature *feature;
> > +	int ret = 0;
> > +
> > +	dfl_fpga_dev_for_each_feature(pdata, feature) {
> > +		if (dfh_type == DFH_TYPE_FIU) {
> > +			if (feature->id == FEATURE_ID_FIU_HEADER ||
> > +			    feature->id == FEATURE_ID_AFU)
> > +				continue;
> > +
> > +			ret |= dfl_uio_remove(feature);
> > +		}
> > +	}
> > +	return ret;
> > +}
> > +EXPORT_SYMBOL_GPL(dfl_fpga_dev_feature_uinit_uio);
> > +
> >  static void dfl_chardev_uinit(void)
> >  {
> >  	int i;
> > -
> >  	for (i = 0; i < DFL_FPGA_DEVT_MAX; i++)
> >  		if (MAJOR(dfl_chrdevs[i].devt)) {
> >  			unregister_chrdev_region(dfl_chrdevs[i].devt,
> > diff --git a/drivers/fpga/dfl.h b/drivers/fpga/dfl.h
> > index a85d1cd7a130..fde0fc902d4d 100644
> > --- a/drivers/fpga/dfl.h
> > +++ b/drivers/fpga/dfl.h
> > @@ -26,6 +26,7 @@
> >  #include <linux/platform_device.h>
> >  #include <linux/slab.h>
> >  #include <linux/uuid.h>
> > +#include <linux/uio_driver.h>
> >  #include <linux/fpga/fpga-region.h>
> >
> >  /* maximum supported number of ports */
> > @@ -232,6 +233,7 @@ struct dfl_feature_irq_ctx {
> >   * struct dfl_feature - sub feature of the feature devices
> >   *
> >   * @dev: ptr to pdev of the feature device which has the sub feature.
> > + * @uio: uio interface for feature.
> >   * @id: sub feature id.
> >   * @index: unique identifier for an sub feature within the feature device.
> >   *	   It is possible that multiply sub features with same feature id are
> > @@ -248,6 +250,8 @@ struct dfl_feature_irq_ctx {
> >   */
> >  struct dfl_feature {
> >  	struct platform_device *dev;
> > +	struct uio_info uio;
> > +	struct mutex lock; /* serialize dev and uio */
> >  	u64 id;
> >  	int index;
> >  	int resource_index;
> > @@ -360,6 +364,11 @@ void dfl_fpga_dev_feature_uinit(struct
> platform_device *pdev);
> >  int dfl_fpga_dev_feature_init(struct platform_device *pdev,
> >  			      struct dfl_feature_driver *feature_drvs);
> >
> > +int dfl_fpga_dev_feature_init_uio(struct platform_device *pdev, int
> dfh_type);
> > +int dfl_fpga_dev_feature_uinit_uio(struct platform_device *pdev, int
> dfh_type);
> > +int dfl_uio_add(struct dfl_feature *feature);
> > +int dfl_uio_remove(struct dfl_feature *feature);
> > +
> >  int dfl_fpga_dev_ops_register(struct platform_device *pdev,
> >  			      const struct file_operations *fops,
> >  			      struct module *owner);
> > diff --git a/uio.c b/uio.c
> > new file mode 100644
> > index 000000000000..50210aab4822
> > --- /dev/null
> > +++ b/uio.c
> > @@ -0,0 +1,56 @@
> > +#include <stdlib.h>
> > +#include <stdio.h>
> > +#include <unistd.h>
> > +#include <sys/mman.h>
> > +#include <sys/types.h>
> > +#include <sys/stat.h>
> > +#include <fcntl.h>
> > +#include <errno.h>
> > +#include <stdint.h>
> > +
> > +int main()
> > +{
> > +	int fd;
> > +	uint64_t *ptr;
> > +	unsigned page_size=sysconf(_SC_PAGESIZE);
> > +	struct stat sb;
> > +
> > +	/*
> > +	 * this is fid 1, thermal mgt
> > +	 * ex/
> > +	 * # cat /sys/class/hwmon/hwmon3/temp1_input
> > +	 * 39000
> > +	 */
> > +	fd = open("/dev/uio0", O_RDONLY|O_SYNC);
> > +	if (fd < 0) {
> > +		perror("uio open:");
> > +		return errno;
> > +	}
> > +
> > +	ptr = (uint64_t *) mmap(NULL, page_size, PROT_READ, MAP_SHARED,
> fd, 0);
> > +	if (!ptr) {
> > +		perror("uio mmap:");
> > +	} else {
> > +
> > +		/* from dfl-fme-main.c :
> > +		 *
> > +		 * #define FME_THERM_RDSENSOR_FMT1	0x10
> > +		 * #define FPGA_TEMPERATURE	GENMASK_ULL(6, 0)
> > +		 *
> > +		 * case hwmon_temp_input:
> > +		 * v = readq(feature->ioaddr +
> FME_THERM_RDSENSOR_FMT1);
> > +		 * *val = (long)(FIELD_GET(FPGA_TEMPERATURE, v) * 1000);
> > +		 * break;
> > +		 */
> > +		uint64_t v = ptr[2];
> > +		v &= (1 << 6) -1;
> > +		v *= 1000;
> > +		printf("Temperature %d\n", v);
> > +
> > +		munmap(ptr, page_size);
> > +	}
> > +	if (close(fd))
> > +		perror("uio close:");
> > +
> > +	return errno;
> > +}
> > --
> > 2.18.4