Re: [PATCH v3 1/2] remoteproc: Add remoteproc character device interface

From: Arnaud POULIQUEN
Date: Wed Jun 17 2020 - 04:45:05 EST



On 6/16/20 9:56 PM, rishabhb@xxxxxxxxxxxxxx wrote:
> On 2020-04-30 01:30, Arnaud POULIQUEN wrote:
>> Hi Rishabh,
>>
>>
>> On 4/21/20 8:10 PM, Rishabh Bhatnagar wrote:
>>> Add the character device interface into remoteproc framework.
>>> This interface can be used in order to boot/shutdown remote
>>> subsystems and provides a basic ioctl based interface to implement
>>> supplementary functionality. An ioctl call is implemented to enable
>>> the shutdown on release feature which will allow remote processors to
>>> be shutdown when the controlling userpsace application crashes or
>>> hangs.
>>>
>>
>> Thanks for intruducing Ioctl, this will help for future evolutions.
>>
>>> Signed-off-by: Rishabh Bhatnagar <rishabhb@xxxxxxxxxxxxxx>
>>> ---
>>> Documentation/userspace-api/ioctl/ioctl-number.rst | 1 +
>>> drivers/remoteproc/Kconfig | 9 ++
>>> drivers/remoteproc/Makefile | 1 +
>>> drivers/remoteproc/remoteproc_cdev.c | 143
>>> +++++++++++++++++++++
>>> drivers/remoteproc/remoteproc_internal.h | 21 +++
>>> include/linux/remoteproc.h | 3 +
>>> include/uapi/linux/remoteproc_cdev.h | 20 +++
>>> 7 files changed, 198 insertions(+)
>>> create mode 100644 drivers/remoteproc/remoteproc_cdev.c
>>> create mode 100644 include/uapi/linux/remoteproc_cdev.h
>>>
>>> diff --git a/Documentation/userspace-api/ioctl/ioctl-number.rst
>>> b/Documentation/userspace-api/ioctl/ioctl-number.rst
>>> index 2e91370..412b2a0 100644
>>> --- a/Documentation/userspace-api/ioctl/ioctl-number.rst
>>> +++ b/Documentation/userspace-api/ioctl/ioctl-number.rst
>>> @@ -337,6 +337,7 @@ Code Seq# Include File
>>> Comments
>>> 0xB4 00-0F linux/gpio.h
>>> <mailto:linux-gpio@xxxxxxxxxxxxxxx>
>>> 0xB5 00-0F uapi/linux/rpmsg.h
>>> <mailto:linux-remoteproc@xxxxxxxxxxxxxxx>
>>> 0xB6 all linux/fpga-dfl.h
>>> +0xB7 all uapi/linux/remoteproc_cdev.h
>>> <mailto:linux-remoteproc@xxxxxxxxxxxxxxx>
>>> 0xC0 00-0F linux/usb/iowarrior.h
>>> 0xCA 00-0F uapi/misc/cxl.h
>>> 0xCA 10-2F uapi/misc/ocxl.h
>>> diff --git a/drivers/remoteproc/Kconfig b/drivers/remoteproc/Kconfig
>>> index de3862c..6374b79 100644
>>> --- a/drivers/remoteproc/Kconfig
>>> +++ b/drivers/remoteproc/Kconfig
>>> @@ -14,6 +14,15 @@ config REMOTEPROC
>>>
>>> if REMOTEPROC
>>>
>>> +config REMOTEPROC_CDEV
>>> + bool "Remoteproc character device interface"
>>> + help
>>> + Say y here to have a character device interface for Remoteproc
>>> + framework. Userspace can boot/shutdown remote processors through
>>> + this interface.
>>> +
>>> + It's safe to say N if you don't want to use this interface.
>>> +
>>> config IMX_REMOTEPROC
>>> tristate "IMX6/7 remoteproc support"
>>> depends on ARCH_MXC
>>> diff --git a/drivers/remoteproc/Makefile b/drivers/remoteproc/Makefile
>>> index e30a1b1..b7d4f77 100644
>>> --- a/drivers/remoteproc/Makefile
>>> +++ b/drivers/remoteproc/Makefile
>>> @@ -9,6 +9,7 @@ remoteproc-y += remoteproc_debugfs.o
>>> remoteproc-y += remoteproc_sysfs.o
>>> remoteproc-y += remoteproc_virtio.o
>>> remoteproc-y += remoteproc_elf_loader.o
>>> +obj-$(CONFIG_REMOTEPROC_CDEV) += remoteproc_cdev.o
>>> obj-$(CONFIG_IMX_REMOTEPROC) += imx_rproc.o
>>> obj-$(CONFIG_MTK_SCP) += mtk_scp.o mtk_scp_ipi.o
>>> obj-$(CONFIG_OMAP_REMOTEPROC) += omap_remoteproc.o
>>> diff --git a/drivers/remoteproc/remoteproc_cdev.c
>>> b/drivers/remoteproc/remoteproc_cdev.c
>>> new file mode 100644
>>> index 0000000..65142ec
>>> --- /dev/null
>>> +++ b/drivers/remoteproc/remoteproc_cdev.c
>>> @@ -0,0 +1,143 @@
>>> +// SPDX-License-Identifier: GPL-2.0-only
>>> +/*
>>> + * Character device interface driver for Remoteproc framework.
>>> + *
>>> + * Copyright (c) 2020, The Linux Foundation. All rights reserved.
>>> + */
>>> +
>>> +#include <linux/cdev.h>
>>> +#include <linux/fs.h>
>>> +#include <linux/module.h>
>>> +#include <linux/mutex.h>
>>> +#include <linux/remoteproc.h>
>>> +#include <uapi/linux/remoteproc_cdev.h>
>>> +#include <linux/uaccess.h>
>>> +
>>> +#include "remoteproc_internal.h"
>>> +
>>> +#define NUM_RPROC_DEVICES 64
>>> +static dev_t rproc_major;
>>> +
>>> +static ssize_t rproc_cdev_write(struct file *filp, const char __user
>>> *buf,
>>> + size_t len, loff_t *pos)
>>> +{
>>> + struct rproc *rproc = container_of(filp->f_inode->i_cdev,
>>> + struct rproc, char_dev);
>>> + int ret = 0;
>>> + char cmd[10];
>>> +
>>> + if (!len || len > sizeof(cmd))
>>> + return -EINVAL;
>>> +
>>> + ret = copy_from_user(cmd, buf, sizeof(cmd));
>>> + if (ret)
>>> + return -EFAULT;
>>> +
>>> + if (sysfs_streq(cmd, "start")) {
>>> + if (rproc->state == RPROC_RUNNING)
>>> + return -EBUSY;
>>> +
>>> + ret = rproc_boot(rproc);
>>> + if (ret)
>>> + dev_err(&rproc->dev, "Boot failed:%d\n", ret);
>>> + } else if (sysfs_streq(cmd, "stop")) {
>>> + if (rproc->state == RPROC_OFFLINE)
>>> + return -ENXIO;
>>
>> returning ENXIO in this case seems to me no appropriate , what about
>> EPERM or
>> EINVAL (rproc_sysfs) ?
>>
>>> +
>>> + rproc_shutdown(rproc);
>>> + } else {
>>> + dev_err(&rproc->dev, "Unrecognized option\n");
>>> + ret = -EINVAL;
>>> + }
>>> +
>>> + return ret ? ret : len;
>>> +}
>>> +
>>> +static long rproc_device_ioctl(struct file *filp, unsigned int ioctl,
>>> + unsigned long arg)
>>> +{
>>> + struct rproc *rproc = container_of(filp->f_inode->i_cdev,
>>> + struct rproc, char_dev);
>>> + void __user *argp = (void __user *)arg;
>>> + int ret;
>>> + bool param;
>>> +
>>> + switch (ioctl) {
>>> + case RPROC_SET_SHUTDOWN_ON_RELEASE:
>>> + ret = copy_from_user(&param, argp, sizeof(bool));
>>> + if (ret) {
>>> + dev_err(&rproc->dev, "Data copy from userspace failed\n");
>>> + return -EINVAL;
>>> + }
>>> + rproc->cdev_put_on_release = param;
>>
>> argp is an void value, where cdev_put_on_release is a bool a check or
>> a conversion seems
>> missing
>>
>>> + break;
>>> + case RPROC_GET_SHUTDOWN_ON_RELEASE:
>>> + ret = copy_to_user(argp, &rproc->cdev_put_on_release,
>>> + sizeof(bool));
>>> + if (ret) {
>>> + dev_err(&rproc->dev, "Data copy to userspace failed\n");
>>> + return -EINVAL;
>>> + }
>>> + break;
>>> + default:
>>> + dev_err(&rproc->dev, "Unsupported ioctl\n");
>>> + return -EINVAL;
>>> + }
>>> + return 0;
>>> +}
>>> +
>>> +static int rproc_cdev_release(struct inode *inode, struct file *filp)
>>> +{
>>> + struct rproc *rproc = container_of(inode->i_cdev, struct rproc,
>>> + char_dev);
>>> +
>>> + if (rproc->cdev_put_on_release && rproc->state != RPROC_OFFLINE)
>>> + rproc_shutdown(rproc);
>>> +
>>> + return 0;
>>> +}
>>> +
>>> +
>>> +static const struct file_operations rproc_fops = {
>>> + .write = rproc_cdev_write,
>>> + .unlocked_ioctl = rproc_device_ioctl,
>>> + .release = rproc_cdev_release,
>>> +};
>>> +
>>> +int rproc_char_device_add(struct rproc *rproc)
>>> +{
>>> + int ret;
>>> + dev_t cdevt;
>>> +
>>> + cdev_init(&rproc->char_dev, &rproc_fops);
>>> + rproc->char_dev.owner = THIS_MODULE;
>>> +
>>> + cdevt = MKDEV(MAJOR(rproc_major), rproc->index);
>>> + ret = cdev_add(&rproc->char_dev, cdevt, 1);
>>> + if (ret < 0)
>>> + goto out;
>>> +
>>> + rproc->dev.devt = cdevt;
>>> +out:
>>> + return ret;
>>> +}
>>> +
>>> +void rproc_char_device_remove(struct rproc *rproc)
>>> +{
>>> + __unregister_chrdev(MAJOR(rproc->dev.devt), rproc->index, 1,
>>> "rproc");
>>> +}
>>> +
>>> +void __init rproc_init_cdev(void)
>>> +{
>>> + int ret;
>>> +
>>> + ret = alloc_chrdev_region(&rproc_major, 0, NUM_RPROC_DEVICES,
>>> "rproc");
>>
>> "remoteproc"instead of "rproc" (in line with sysfs and debugfs naming)
>> .
>>
>>> + if (ret < 0)
>>> + pr_err("Failed to alloc rproc_cdev region, err %d\n", ret);
>>> +}
>>> +
>>> +void __exit rproc_exit_cdev(void)
>>> +{
>>> + unregister_chrdev_region(MKDEV(MAJOR(rproc_major), 0),
>>> + NUM_RPROC_DEVICES);
>>> +}
>>> diff --git a/drivers/remoteproc/remoteproc_internal.h
>>> b/drivers/remoteproc/remoteproc_internal.h
>>> index 493ef92..fb9d891 100644
>>> --- a/drivers/remoteproc/remoteproc_internal.h
>>> +++ b/drivers/remoteproc/remoteproc_internal.h
>>> @@ -47,6 +47,27 @@ struct dentry *rproc_create_trace_file(const char
>>> *name, struct rproc *rproc,
>>> int rproc_init_sysfs(void);
>>> void rproc_exit_sysfs(void);
>>>
>>> +#ifdef CONFIG_REMOTEPROC_CDEV
>>> +void rproc_init_cdev(void);
>>> +void rproc_exit_cdev(void);
>>> +int rproc_char_device_add(struct rproc *rproc);
>>> +void rproc_char_device_remove(struct rproc *rproc);
>>> +#else
>>> +static inline void rproc_init_cdev(void)
>>> +{
>>> +}
>>> +static inline void rproc_exit_cdev(void)
>>> +{
>>> +}
>>> +static inline int rproc_char_device_add(struct rproc *rproc)
>>> +{
>>> + return 0;
>>> +}
>>> +static inline void rproc_char_device_remove(struct rproc *rproc)
>>> +{
>>> +}
>>> +#endif
>>> +
>>> void rproc_free_vring(struct rproc_vring *rvring);
>>> int rproc_alloc_vring(struct rproc_vdev *rvdev, int i);
>>>
>>> diff --git a/include/linux/remoteproc.h b/include/linux/remoteproc.h
>>> index 16ad666..9bd2ff5 100644
>>> --- a/include/linux/remoteproc.h
>>> +++ b/include/linux/remoteproc.h
>>> @@ -40,6 +40,7 @@
>>> #include <linux/virtio.h>
>>> #include <linux/completion.h>
>>> #include <linux/idr.h>
>>> +#include <linux/cdev.h>
>>> #include <linux/of.h>
>>>
>>> /**
>>> @@ -514,6 +515,8 @@ struct rproc {
>>> bool auto_boot;
>>> struct list_head dump_segments;
>>> int nb_vdev;
>>> + struct cdev char_dev;
>>> + bool cdev_put_on_release;
>>> };
>>
>> These parameters are local variables of rproc_cdev. Could be defined
>> in a separate structure.
>> with a pointer in rproc to this structure.
>>
>>>
>>> /**
>>> diff --git a/include/uapi/linux/remoteproc_cdev.h
>>> b/include/uapi/linux/remoteproc_cdev.h
>>> new file mode 100644
>>> index 0000000..3975120
>>> --- /dev/null
>>> +++ b/include/uapi/linux/remoteproc_cdev.h
>>> @@ -0,0 +1,20 @@
>>> +/* SPDX-License-Identifier: GPL-2.0-only WITH Linux-syscall-note */
>>> +/*
>>> + * IOCTLs for Remoteproc's character device interface.
>>> + *
>>> + * Copyright (c) 2020, The Linux Foundation. All rights reserved.
>>> + */
>>> +
>>> +
>>> +#ifndef _UAPI_REMOTEPROC_CDEV_H_
>>> +#define _UAPI_REMOTEPROC_CDEV_H_
>>> +
>>> +#include <linux/ioctl.h>
>>> +#include <linux/types.h>
>>> +
>>> +#define RPROC_MAGIC 0xB7
>>> +
>>> +#define RPROC_SET_SHUTDOWN_ON_RELEASE _IOW(RPROC_MAGIC, 1, int)
>>> +#define RPROC_GET_SHUTDOWN_ON_RELEASE _IOR(RPROC_MAGIC, 2, int)
>>> +
>>> +#endif
>>>
>> IOCTLs should probaly be documented.
> I have added documentation to
> Documentation/userspace-api/ioctl/ioctl-number.rst
> Is there another place where I need to add documentation for this?

Could you add in this file comments that describe
the IOCTL usage and associated parameter?

Regards,
Arnaud

>>
>> Thanks,
>> Arnaud