Subject: Re: [PATCH 3/4] remoteproc: Add a sysfs interface for firmware and
 state
To: Matt Redfearn <matt.redfearn@imgtec.com>,
        Bjorn Andersson <bjorn.andersson@linaro.org>,
        Ohad Ben-Cohen <ohad@wizery.com>
References: <1476193185-32107-1-git-send-email-matt.redfearn@imgtec.com>
 <1476193185-32107-4-git-send-email-matt.redfearn@imgtec.com>
 <d206a09e-4db6-2199-2a5f-a81430c3adae@st.com>
 <f070f6e0-275c-1937-2bde-adee0c1fd08e@imgtec.com>
CC: <linux-remoteproc@vger.kernel.org>, <linux-kernel@vger.kernel.org>
From: loic pallardy <loic.pallardy@st.com>
Message-ID: <45167a9c-80ee-2af1-2ec5-db1eb1eef883@st.com>
Date: Thu, 13 Oct 2016 16:39:37 +0200
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On 10/13/2016 04:25 PM, Matt Redfearn wrote:
> Hi Loic,
>
>
> On 13/10/16 14:56, loic pallardy wrote:
>>
>>
>> On 10/11/2016 03:39 PM, Matt Redfearn wrote:
>>> This patch adds a sysfs interface to rproc allowing the firmware name
>>> and processor state to be changed dynamically.
>>>
>>> State was previously available in debugfs, and is replicated here. The
>>> firmware file allows retrieval of the running firmware name, and a new
>>> one to be specified at run time, so long as the remote processor has
>>> been stopped.
>>>
>>> Signed-off-by: Matt Redfearn <matt.redfearn@imgtec.com>
>>>
>>> ---
>>>
>>>  Documentation/ABI/testing/sysfs-class-remoteproc |  50 +++++++++
>>>  drivers/remoteproc/Makefile                      |   1 +
>>>  drivers/remoteproc/remoteproc_core.c             |   3 +
>>>  drivers/remoteproc/remoteproc_internal.h         |   5 +
>>>  drivers/remoteproc/remoteproc_sysfs.c            | 132
>>> +++++++++++++++++++++++
>>>  5 files changed, 191 insertions(+)
>>>  create mode 100644 Documentation/ABI/testing/sysfs-class-remoteproc
>>>  create mode 100644 drivers/remoteproc/remoteproc_sysfs.c
>>>
>>> diff --git a/Documentation/ABI/testing/sysfs-class-remoteproc
>>> b/Documentation/ABI/testing/sysfs-class-remoteproc
>>> new file mode 100644
>>> index 000000000000..d188afebc8ba
>>> --- /dev/null
>>> +++ b/Documentation/ABI/testing/sysfs-class-remoteproc
>>> @@ -0,0 +1,50 @@
>>> +What:        /sys/class/remoteproc/.../firmware
>>> +Date:        October 2016
>>> +Contact:    Matt Redfearn <matt.redfearn@imgtec.com>
>>> +Description:    Remote processor firmware
>>> +
>>> +        Reports the name of the firmware currently loaded to the
>>> +        remote processor.
>>> +
>>> +        To change the running firmware, ensure the remote processor is
>>> +        stopped (using /sys/class/remoteproc/.../state) and write a
>>> new filename.
>>> +
>>> +What:        /sys/class/remoteproc/.../state
>>> +Date:        October 2016
>>> +Contact:    Matt Redfearn <matt.redfearn@imgtec.com>
>>> +Description:    Remote processor state
>>> +
>>> +        Reports the state of the remote processor, which will be one
>>> of:
>>> +
>>> +        "offline"
>>> +        "suspended"
>>> +        "running"
>>> +        "crashed"
>>> +        "invalid"
>>> +
>>> +        "offline" means the remote processor is powered off.
>>> +
>>> +        "suspended" means that the remote processor is suspended and
>>> +        must be woken to receive messages.
>>> +
>>> +        "running" is the normal state of an available remote processor
>>> +
>>> +        "crashed" indicates that a problem/crash has been detected on
>>> +        the remote processor.
>>> +
>>> +        "invalid" is returned if the remote processor is in an
>>> +        unknown state.
>>> +
>>> +        Writing this file controls the state of the remote processor.
>>> +        The following states can be written:
>>> +
>>> +        "start"
>>> +        "stop"
>>> +
>>> +        Writing "start" will attempt to start the processor running the
>>> +        firmware indicated by, or written to,
>>> +        /sys/class/remoteproc/.../firmware. The remote processor should
>>> +        transition to "running" state.
>>> +
>>> +        Writing "stop" will attempt to halt the remote processor and
>>> +        return it to the "offline" state.
>>> diff --git a/drivers/remoteproc/Makefile b/drivers/remoteproc/Makefile
>>> index 92d3758bd15c..666258bd80aa 100644
>>> --- a/drivers/remoteproc/Makefile
>>> +++ b/drivers/remoteproc/Makefile
>>> @@ -5,6 +5,7 @@
>>>  obj-$(CONFIG_REMOTEPROC)        += remoteproc.o
>>>  remoteproc-y                := remoteproc_core.o
>>>  remoteproc-y                += remoteproc_debugfs.o
>>> +remoteproc-y                += remoteproc_sysfs.o
>>>  remoteproc-y                += remoteproc_virtio.o
>>>  remoteproc-y                += remoteproc_elf_loader.o
>>>  obj-$(CONFIG_OMAP_REMOTEPROC)        += omap_remoteproc.o
>>> diff --git a/drivers/remoteproc/remoteproc_core.c
>>> b/drivers/remoteproc/remoteproc_core.c
>>> index 2152b484f314..642c5b58fec5 100644
>>> --- a/drivers/remoteproc/remoteproc_core.c
>>> +++ b/drivers/remoteproc/remoteproc_core.c
>>> @@ -1455,6 +1455,7 @@ struct rproc *rproc_alloc(struct device *dev,
>>> const char *name,
>>>      device_initialize(&rproc->dev);
>>>      rproc->dev.parent = dev;
>>>      rproc->dev.type = &rproc_type;
>>> +    rproc->dev.class = &rproc_class;
>>>
>>>      /* Assign a unique device index and name */
>>>      rproc->index = ida_simple_get(&rproc_dev_index, 0, 0, GFP_KERNEL);
>>> @@ -1580,6 +1581,7 @@ EXPORT_SYMBOL(rproc_report_crash);
>>>
>>>  static int __init remoteproc_init(void)
>>>  {
>>> +    rproc_init_sysfs();
>>>      rproc_init_debugfs();
>>>
>>>      return 0;
>>> @@ -1591,6 +1593,7 @@ static void __exit remoteproc_exit(void)
>>>      ida_destroy(&rproc_dev_index);
>>>
>>>      rproc_exit_debugfs();
>>> +    rproc_exit_sysfs();
>>>  }
>>>  module_exit(remoteproc_exit);
>>>
>>> diff --git a/drivers/remoteproc/remoteproc_internal.h
>>> b/drivers/remoteproc/remoteproc_internal.h
>>> index 837faf2677a6..2beb86ddfacc 100644
>>> --- a/drivers/remoteproc/remoteproc_internal.h
>>> +++ b/drivers/remoteproc/remoteproc_internal.h
>>> @@ -64,6 +64,11 @@ void rproc_create_debug_dir(struct rproc *rproc);
>>>  void rproc_init_debugfs(void);
>>>  void rproc_exit_debugfs(void);
>>>
>>> +/* from remoteproc_sysfs.c */
>>> +extern struct class rproc_class;
>> struct class rproc_class should be static to remoteproc_sysfs.c file.
>> It will be better to create a new interface like rproc_register_sysfs
>> to associate rproc_class to rproc device.
>
> It would be nice if that were possible, but since the class has to
> associated with the devices created within remoteproc_core, as it stands
> we must have visibility of this symbol there, see above the change to
> drivers/remoteproc/remoteproc_core.c line 1455.
> The alternative would be a utility function in remoteproc_sysfs.c to
> associate the class with an rproc device, it depends what the preference
> would be.

Yes it will be my preference. remoteproc_sysfs.c file to provide a new 
service like:
void rproc_register_sysfs(struct rproc *rproc) {
	rproc->dev.class = &rproc_class;
}

and to call this function from rproc_alloc

/Loic
>
> Thanks,
> Matt
>
>>
>>> +int rproc_init_sysfs(void);
>>> +void rproc_exit_sysfs(void);
>>> +
>>>  void rproc_free_vring(struct rproc_vring *rvring);
>>>  int rproc_alloc_vring(struct rproc_vdev *rvdev, int i);
>>>
>>> diff --git a/drivers/remoteproc/remoteproc_sysfs.c
>>> b/drivers/remoteproc/remoteproc_sysfs.c
>>> new file mode 100644
>>> index 000000000000..892599863ca6
>>> --- /dev/null
>>> +++ b/drivers/remoteproc/remoteproc_sysfs.c
>>> @@ -0,0 +1,132 @@
>>> +/*
>>> + * Remote Processor Framework
>>> + *
>>> + * This program is free software; you can redistribute it and/or
>>> + * modify it under the terms of the GNU General Public License
>>> + * version 2 as published by the Free Software Foundation.
>>> + *
>>> + * This program is distributed in the hope that it will be useful,
>>> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
>>> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
>>> + * GNU General Public License for more details.
>>> + */
>>> +
>>> +#include <linux/remoteproc.h>
>>> +
>>> +#include "remoteproc_internal.h"
>>> +
>>> +#define to_rproc(d) container_of(d, struct rproc, dev)
>>> +
>>> +/* Expose the loaded / running firmware name via sysfs */
>>> +static ssize_t firmware_show(struct device *dev, struct
>>> device_attribute *attr,
>>> +              char *buf)
>>> +{
>>> +    struct rproc *rproc = to_rproc(dev);
>>> +
>>> +    if (rproc->firmware)
>>> +        return sprintf(buf, "%s\n", rproc->firmware);
>>> +    else
>>> +        return sprintf(buf, "unknown");
>>> +}
>>> +
>>> +/* Change firmware name via sysfs */
>>> +static ssize_t firmware_store(struct device *dev,
>>> +                  struct device_attribute *attr,
>>> +                  const char *buf, size_t count)
>>> +{
>>> +    struct rproc *rproc = to_rproc(dev);
>>> +    int err;
>>> +
>>> +    err = rproc_change_firmware(rproc, buf);
>>> +    return err ? err : count;
>>> +}
>>> +static DEVICE_ATTR_RW(firmware);
>>> +
>>> +
>>> +/*
>>> + * A state-to-string lookup table, for exposing a human readable state
>>> + * via sysfs. Always keep in sync with enum rproc_state
>>> + */
>>> +static const char * const rproc_state_string[] = {
>>> +    "offline",
>>> +    "suspended",
>>> +    "running",
>>> +    "crashed",
>>> +    "invalid",
>>> +};
>>> +
>>> +/* Expose the state of the remote processor via sysfs */
>>> +static ssize_t state_show(struct device *dev, struct
>>> device_attribute *attr,
>>> +              char *buf)
>>> +{
>>> +    struct rproc *rproc = to_rproc(dev);
>>> +    unsigned int state;
>>> +
>>> +    state = rproc->state > RPROC_LAST ? RPROC_LAST : rproc->state;
>>> +    return scnprintf(buf, 30, "%.28s (%d)\n",
>>> +             rproc_state_string[state], rproc->state);
>>> +}
>>> +
>>> +/* Change remote processor state via sysfs */
>>> +static ssize_t state_store(struct device *dev,
>>> +                  struct device_attribute *attr,
>>> +                  const char *buf, size_t count)
>>> +{
>>> +    struct rproc *rproc = to_rproc(dev);
>>> +    int ret = 0;
>>> +    int len = count;
>>> +
>>> +    if (buf[len - 1] == '\n')
>>> +        len--;
>>> +
>>> +    if (!strncmp(buf, "start", len)) {
>>> +        if (rproc->state == RPROC_RUNNING)
>>> +            return -EBUSY;
>>> +
>>> +        ret = rproc_boot(rproc);
>>> +        if (ret)
>>> +            dev_err(&rproc->dev, "Boot failed: %d\n", ret);
>>> +    } else if (!strncmp(buf, "stop", len)) {
>>> +        rproc_shutdown(rproc);
>>> +    } else {
>>> +        dev_err(&rproc->dev, "Unrecognised option: %s\n", buf);
>>> +        ret = -EINVAL;
>>> +    }
>>> +    return ret ? ret : count;
>>> +}
>>> +static DEVICE_ATTR_RW(state);
>>> +
>>> +static const struct attribute *rproc_attrs[] = {
>>> +    &dev_attr_firmware.attr,
>>> +    &dev_attr_state.attr,
>>> +    NULL
>>> +};
>>> +
>>> +static const struct attribute_group rproc_devgroup = {
>>> +    .attrs = rproc_attrs
>>> +};
>>> +
>>> +static const struct attribute_group *rproc_devgroups[] = {
>>> +    &rproc_devgroup,
>>> +    NULL
>>> +};
>>> +
>>> +struct class rproc_class = {
>> static ?
>>
>> Regards,
>> Loic
>>> +    .name        = "remoteproc",
>>> +    .dev_groups    = rproc_devgroups,
>>> +};
>>> +
>>> +int __init rproc_init_sysfs(void)
>>> +{
>>> +    /* create remoteproc device class for sysfs */
>>> +    int err = class_register(&rproc_class);
>>> +
>>> +    if (err)
>>> +        pr_err("remoteproc: unable to register class\n");
>>> +    return err;
>>> +}
>>> +
>>> +void __exit rproc_exit_sysfs(void)
>>> +{
>>> +    class_unregister(&rproc_class);
>>> +}
>>>
>