[RFC simple allocator v2 1/2] Create Simple Allocator module

Daniel Vetter daniel.vetter at ffwll.ch
Tue Feb 14 19:33:58 UTC 2017


On Mon, Feb 13, 2017 at 3:45 PM, Benjamin Gaignard
<benjamin.gaignard at linaro.org> wrote:
> This is the core of simple allocator module.
> It aim to offert one common ioctl to allocate specific memory.
>
> version 2:
> - rebased on 4.10-rc7
>
> Signed-off-by: Benjamin Gaignard <benjamin.gaignard at linaro.org>

Why not ION? It's a bit a broken record question, but if there is a
clear answer it should be in the patch&docs ...
-Daniel

> ---
>  Documentation/simple-allocator.txt              |  81 +++++++++++
>  drivers/Kconfig                                 |   2 +
>  drivers/Makefile                                |   1 +
>  drivers/simpleallocator/Kconfig                 |  10 ++
>  drivers/simpleallocator/Makefile                |   1 +
>  drivers/simpleallocator/simple-allocator-priv.h |  33 +++++
>  drivers/simpleallocator/simple-allocator.c      | 180 ++++++++++++++++++++++++
>  include/uapi/linux/simple-allocator.h           |  35 +++++
>  8 files changed, 343 insertions(+)
>  create mode 100644 Documentation/simple-allocator.txt
>  create mode 100644 drivers/simpleallocator/Kconfig
>  create mode 100644 drivers/simpleallocator/Makefile
>  create mode 100644 drivers/simpleallocator/simple-allocator-priv.h
>  create mode 100644 drivers/simpleallocator/simple-allocator.c
>  create mode 100644 include/uapi/linux/simple-allocator.h
>
> diff --git a/Documentation/simple-allocator.txt b/Documentation/simple-allocator.txt
> new file mode 100644
> index 0000000..89ba883
> --- /dev/null
> +++ b/Documentation/simple-allocator.txt
> @@ -0,0 +1,81 @@
> +Simple Allocator Framework
> +
> +Simple Allocator offer a single ioctl SA_IOC_ALLOC to allocate buffers
> +on dedicated memory regions and export them as a dmabuf file descriptor.
> +Using dmabuf file descriptor allow to share this memory between processes
> +and/or import it into other frameworks like v4l2 or drm/kms (prime).
> +When userland wants to free the memory only a call to close() in needed
> +so it could done even without knowing that buffer has been allocated by
> +simple allocator ioctl.
> +
> +Each memory regions will be seen as a filein /dev/.
> +For example CMA regions will exposed has /dev/cmaX.
> +
> +Implementing a simple allocator
> +-------------------------------
> +
> +Simple Allocator provide helpers functions to register/unregister an
> +allocator:
> +- simple_allocator_register(struct sa_device *sadev)
> +  Register simple_allocator_device using sa_device structure where name,
> +  owner and allocate fields must be set.
> +
> +- simple_allocator_unregister(struct sa_device *sadev)
> +  Unregister a simple allocator device.
> +
> +Using Simple Allocator /dev interface example
> +---------------------------------------------
> +
> +This example of code allocate a buffer on the first CMA region (/dev/cma0)
> +before mmap and close it.
> +
> +#include <errno.h>
> +#include <fcntl.h>
> +#include <stdio.h>
> +#include <stdlib.h>
> +#include <string.h>
> +#include <unistd.h>
> +#include <sys/ioctl.h>
> +#include <sys/mman.h>
> +#include <sys/stat.h>
> +#include <sys/types.h>
> +
> +#include "simple-allocator.h"
> +
> +#define LENGTH 1024*16
> +
> +void main (void)
> +{
> +       struct simple_allocate_data data;
> +       int fd = open("/dev/cma0", O_RDWR, 0);
> +       int ret;
> +       void *mem;
> +
> +       if (fd < 0) {
> +               printf("Can't open /dev/cma0\n");
> +               return;
> +       }
> +
> +       memset(&data, 0, sizeof(data));
> +
> +       data.length = LENGTH;
> +       data.flags = O_RDWR | O_CLOEXEC;
> +
> +       ret = ioctl(fd, SA_IOC_ALLOC, &data);
> +       if (ret) {
> +               printf("Buffer allocation failed\n");
> +               goto end;
> +       }
> +
> +       mem = mmap(0, LENGTH, PROT_READ | PROT_WRITE, MAP_SHARED, data.fd, 0);
> +       if (mem == MAP_FAILED) {
> +               printf("mmap failed\n");
> +       }
> +
> +       memset(mem, 0xFF, LENGTH);
> +       munmap(mem, LENGTH);
> +
> +       printf("test simple allocator CMA OK\n");
> +end:
> +       close(fd);
> +}
> diff --git a/drivers/Kconfig b/drivers/Kconfig
> index e1e2066..a6d8828 100644
> --- a/drivers/Kconfig
> +++ b/drivers/Kconfig
> @@ -202,4 +202,6 @@ source "drivers/hwtracing/intel_th/Kconfig"
>
>  source "drivers/fpga/Kconfig"
>
> +source "drivers/simpleallocator/Kconfig"
> +
>  endmenu
> diff --git a/drivers/Makefile b/drivers/Makefile
> index 060026a..5081eb8 100644
> --- a/drivers/Makefile
> +++ b/drivers/Makefile
> @@ -173,3 +173,4 @@ obj-$(CONFIG_STM)           += hwtracing/stm/
>  obj-$(CONFIG_ANDROID)          += android/
>  obj-$(CONFIG_NVMEM)            += nvmem/
>  obj-$(CONFIG_FPGA)             += fpga/
> +obj-$(CONFIG_SIMPLE_ALLOCATOR)         += simpleallocator/
> diff --git a/drivers/simpleallocator/Kconfig b/drivers/simpleallocator/Kconfig
> new file mode 100644
> index 0000000..c6fc2e3
> --- /dev/null
> +++ b/drivers/simpleallocator/Kconfig
> @@ -0,0 +1,10 @@
> +menu "Simple Allocator"
> +
> +config SIMPLE_ALLOCATOR
> +       tristate "Simple Alllocator Framework"
> +       select DMA_SHARED_BUFFER
> +       ---help---
> +          The Simple Allocator Framework adds an API to allocate and share
> +          memory in userland.
> +
> +endmenu
> diff --git a/drivers/simpleallocator/Makefile b/drivers/simpleallocator/Makefile
> new file mode 100644
> index 0000000..e27c6ad
> --- /dev/null
> +++ b/drivers/simpleallocator/Makefile
> @@ -0,0 +1 @@
> +obj-$(CONFIG_SIMPLE_ALLOCATOR) += simple-allocator.o
> diff --git a/drivers/simpleallocator/simple-allocator-priv.h b/drivers/simpleallocator/simple-allocator-priv.h
> new file mode 100644
> index 0000000..33f5a33
> --- /dev/null
> +++ b/drivers/simpleallocator/simple-allocator-priv.h
> @@ -0,0 +1,33 @@
> +/*
> + * Copyright (C) Linaro 2016
> + *
> + * Author: Benjamin Gaignard <benjamin.gaignard at linaro.org>
> + *
> + * License terms:  GNU General Public License (GPL)
> + */
> +
> +#ifndef _SIMPLE_ALLOCATOR_PRIV_H_
> +#define _SIMPLE_ALLOCATOR_PRIV_H_
> +
> +#include <linux/cdev.h>
> +#include <linux/device.h>
> +#include <linux/dma-buf.h>
> +
> +/**
> + * struct sa_device - simple allocator device
> + * @owner: module owner, must be set to THIS_MODULE
> + * @name: name of the allocator
> + * @allocate: callabck for memory allocation
> + */
> +struct sa_device {
> +       struct device   dev;
> +       struct cdev     chrdev;
> +       struct module   *owner;
> +       const char      *name;
> +       struct dma_buf *(*allocate)(struct sa_device *, u64 length, u32 flags);
> +};
> +
> +int simple_allocator_register(struct sa_device *sadev);
> +void simple_allocator_unregister(struct sa_device *sadev);
> +
> +#endif
> diff --git a/drivers/simpleallocator/simple-allocator.c b/drivers/simpleallocator/simple-allocator.c
> new file mode 100644
> index 0000000..d89ccbf
> --- /dev/null
> +++ b/drivers/simpleallocator/simple-allocator.c
> @@ -0,0 +1,180 @@
> +/*
> + * Copyright (C) Linaro 2016
> + *
> + * Author: Benjamin Gaignard <benjamin.gaignard at linaro.org>
> + *
> + * License terms:  GNU General Public License (GPL)
> + */
> +
> +#include <linux/module.h>
> +#include <linux/simple-allocator.h>
> +#include <linux/uaccess.h>
> +
> +#include "simple-allocator-priv.h"
> +
> +#define SA_MAJOR       222
> +#define SA_NUM_DEVICES 256
> +#define SA_NAME                "simple_allocator"
> +
> +static int sa_minor;
> +
> +static struct class sa_class = {
> +       .name = SA_NAME,
> +};
> +
> +static long sa_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
> +{
> +       struct sa_device *sadev = filp->private_data;
> +       int ret = -ENODEV;
> +
> +       switch (cmd) {
> +       case SA_IOC_ALLOC:
> +       {
> +               struct simple_allocate_data data;
> +               struct dma_buf *dmabuf;
> +
> +               if (copy_from_user(&data, (void __user *)arg, _IOC_SIZE(cmd)))
> +                       return -EFAULT;
> +
> +               if (data.version != 0)
> +                       return -EINVAL;
> +
> +               dmabuf = sadev->allocate(sadev, data.length, data.flags);
> +               if (!dmabuf)
> +                       return -EINVAL;
> +
> +               data.fd = dma_buf_fd(dmabuf, data.flags);
> +               if (data.fd < 0) {
> +                       dma_buf_put(dmabuf);
> +                       return -EINVAL;
> +               }
> +
> +               data.length = dmabuf->size;
> +
> +               if (copy_to_user((void __user *)arg, &data, _IOC_SIZE(cmd))) {
> +                       dma_buf_put(dmabuf);
> +                       return -EFAULT;
> +               }
> +
> +               return 0;
> +       }
> +       }
> +       return ret;
> +}
> +
> +static int sa_open(struct inode *inode, struct file *filp)
> +{
> +       struct sa_device *sadev = container_of(inode->i_cdev,
> +                                              struct sa_device, chrdev);
> +
> +       if (!sadev)
> +               return -ENODEV;
> +
> +       get_device(&sadev->dev);
> +       filp->private_data = sadev;
> +       return 0;
> +}
> +
> +static int sa_release(struct inode *inode, struct file *filp)
> +{
> +       struct sa_device *sadev = container_of(inode->i_cdev,
> +                                              struct sa_device, chrdev);
> +
> +       if (!sadev)
> +               return -ENODEV;
> +
> +       put_device(&sadev->dev);
> +       return 0;
> +}
> +
> +static const struct file_operations sa_fops = {
> +       .owner = THIS_MODULE,
> +       .open = sa_open,
> +       .release = sa_release,
> +       .unlocked_ioctl = sa_ioctl,
> +};
> +
> +/**
> + * simple_allocator_register - register a simple allocator
> + * @sadev: simple allocator structure to be registered
> + *
> + * Return 0 if allocator has been regsitered, either a negative value.
> + */
> +int simple_allocator_register(struct sa_device *sadev)
> +{
> +       int ret;
> +
> +       if (!sadev->name || !sadev->allocate)
> +               return -EINVAL;
> +
> +       cdev_init(&sadev->chrdev, &sa_fops);
> +       sadev->chrdev.owner = sadev->owner;
> +
> +       ret = cdev_add(&sadev->chrdev, MKDEV(SA_MAJOR, sa_minor), 1);
> +       if (ret < 0)
> +               return ret;
> +
> +       sadev->dev.class = &sa_class;
> +       sadev->dev.devt = MKDEV(SA_MAJOR, sa_minor);
> +       dev_set_name(&sadev->dev, "%s%d", sadev->name, sa_minor);
> +       ret = device_register(&sadev->dev);
> +       if (ret < 0)
> +               goto cleanup;
> +
> +       sa_minor++;
> +       return 0;
> +
> +cleanup:
> +       cdev_del(&sadev->chrdev);
> +       return ret;
> +}
> +EXPORT_SYMBOL_GPL(simple_allocator_register);
> +
> +/**
> + * simple_allocator_unregister - unregister a simple allocator
> + * @sadev: simple allocator device to be unregistered
> + */
> +void simple_allocator_unregister(struct sa_device *sadev)
> +{
> +       if (!sadev)
> +               return;
> +
> +       cdev_del(&sadev->chrdev);
> +       device_del(&sadev->dev);
> +       put_device(&sadev->dev);
> +}
> +EXPORT_SYMBOL_GPL(simple_allocator_unregister);
> +
> +static int __init sa_init(void)
> +{
> +       dev_t dev = MKDEV(SA_MAJOR, 0);
> +       int ret;
> +
> +       ret = register_chrdev_region(dev, SA_NUM_DEVICES, SA_NAME);
> +       if (ret < 0)
> +               return ret;
> +
> +       ret = class_register(&sa_class);
> +       if (ret < 0) {
> +               unregister_chrdev_region(dev, SA_NUM_DEVICES);
> +               return -EIO;
> +       }
> +
> +       return 0;
> +}
> +
> +static void __exit sa_exit(void)
> +{
> +       dev_t dev = MKDEV(SA_MAJOR, 0);
> +
> +       class_unregister(&sa_class);
> +       unregister_chrdev_region(dev, SA_NUM_DEVICES);
> +}
> +
> +subsys_initcall(sa_init);
> +module_exit(sa_exit);
> +
> +MODULE_AUTHOR("Benjamin Gaignard <benjamin.gaignard at linaro.org>");
> +MODULE_DESCRIPTION("Simple allocator");
> +MODULE_LICENSE("GPL");
> +MODULE_ALIAS_CHARDEV_MAJOR(SA_MAJOR);
> diff --git a/include/uapi/linux/simple-allocator.h b/include/uapi/linux/simple-allocator.h
> new file mode 100644
> index 0000000..5520a85
> --- /dev/null
> +++ b/include/uapi/linux/simple-allocator.h
> @@ -0,0 +1,35 @@
> +/*
> + * Copyright (C) Linaro 2016
> + *
> + * Author: Benjamin Gaignard <benjamin.gaignard at linaro.org>
> + *
> + * License terms:  GNU General Public License (GPL), version 2
> + */
> +
> +#ifndef _SIMPLE_ALLOCATOR_H_
> +#define _SIMPLE_ALLOCATOR_H_
> +
> +#include <linux/ioctl.h>
> +#include <linux/types.h>
> +
> +/**
> + * struct simple_allocate_data - allocation parameters
> + * @version:   structure version (must be set to 0)
> + * @length:    size of the requested buffer
> + * @flags:     mode flags for the file like O_RDWR or O_CLOEXEC
> + * @fd:                returned file descriptor
> + */
> +struct simple_allocate_data {
> +       __u64 version;
> +       __u64 length;
> +       __u32 flags;
> +       __u32 reserved1;
> +       __s32 fd;
> +       __u32 reserved2;
> +};
> +
> +#define SA_IOC_MAGIC 'S'
> +
> +#define SA_IOC_ALLOC _IOWR(SA_IOC_MAGIC, 0, struct simple_allocate_data)
> +
> +#endif
> --
> 1.9.1
>



-- 
Daniel Vetter
Software Engineer, Intel Corporation
+41 (0) 79 365 57 48 - http://blog.ffwll.ch


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