Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
Subject: Re: [PATCH v3 1/2] remoteproc: Add remoteproc character device
 interface
To:     "rishabhb@codeaurora.org" <rishabhb@codeaurora.org>
CC:     "linux-remoteproc@vger.kernel.org" <linux-remoteproc@vger.kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "bjorn.andersson@linaro.org" <bjorn.andersson@linaro.org>,
        "mathieu.poirier@linaro.org" <mathieu.poirier@linaro.org>,
        "ohad@wizery.com" <ohad@wizery.com>,
        "tsoni@codeaurora.org" <tsoni@codeaurora.org>,
        "psodagud@codeaurora.org" <psodagud@codeaurora.org>,
        "sidgup@codeaurora.org" <sidgup@codeaurora.org>,
        "linux-remoteproc-owner@vger.kernel.org" 
        <linux-remoteproc-owner@vger.kernel.org>
References: <1587492618-15896-1-git-send-email-rishabhb@codeaurora.org>
 <1587492618-15896-2-git-send-email-rishabhb@codeaurora.org>
 <d72ead5a-b25a-d4e2-4bbf-1790d2a64fb8@st.com>
 <d9a477cbbf19ed50af49aee7c6699e09@codeaurora.org>
From:   Arnaud POULIQUEN <arnaud.pouliquen@st.com>
Message-ID: <3738198d-53d4-2fe6-a92b-2db0cd0afa68@st.com>
Date:   Wed, 17 Jun 2020 10:44:41 +0200
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101
 Thunderbird/68.8.0
MIME-Version: 1.0
In-Reply-To: <d9a477cbbf19ed50af49aee7c6699e09@codeaurora.org>
Content-Type: text/plain; charset="utf-8"
Content-Language: en-US
Content-Transfer-Encoding: 7bit
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk


On 6/16/20 9:56 PM, rishabhb@codeaurora.org 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@codeaurora.org>
>>> ---
>>>  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@vger.kernel.org>
>>>  0xB5  00-0F  uapi/linux/rpmsg.h                                      
>>> <mailto:linux-remoteproc@vger.kernel.org>
>>>  0xB6  all    linux/fpga-dfl.h
>>> +0xB7  all    uapi/linux/remoteproc_cdev.h			     
>>> <mailto:linux-remoteproc@vger.kernel.org>
>>>  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