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SubjectRe: [PATCH v3 1/2] remoteproc: Add a sysfs interface for firmware and state
HI Matt,

Thanks for your patch. I am trying it.

Please see my questions inline.

Thanks,
Wendy

On Wed, Oct 19, 2016 at 5:05 AM, Matt Redfearn <matt.redfearn@imgtec.com> 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>
>
> ---
>
> Changes in v3:
> Drop call to rproc_add_virtio_devices from sysfs firmware_store
> Use strcspn to find firmware name length
> Explicit indexes for state strings
>
> Changes in v2:
> Have firmware_store perform the necessary steps inline.
> Use sysfs_streq when dealing with writes to sysfs files
>
> 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 | 151 +++++++++++++++++++++++
> 5 files changed, 210 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 6dfb62ed643f..6da9b12f9798 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 ccc2a73e94dd..b1860949d106 100644
> --- a/drivers/remoteproc/remoteproc_core.c
> +++ b/drivers/remoteproc/remoteproc_core.c
> @@ -1347,6 +1347,7 @@ 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);
> @@ -1485,6 +1486,7 @@ EXPORT_SYMBOL(rproc_report_crash);
>
> static int __init remoteproc_init(void)
> {
> + rproc_init_sysfs();
> rproc_init_debugfs();
>
> return 0;
> @@ -1496,6 +1498,7 @@ 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 4cf93ca2816e..c2c3e4762b90 100644
> --- a/drivers/remoteproc/remoteproc_internal.h
> +++ b/drivers/remoteproc/remoteproc_internal.h
> @@ -63,6 +63,11 @@ 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;
> +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..bc5b0e00efb1
> --- /dev/null
> +++ b/drivers/remoteproc/remoteproc_sysfs.c
> @@ -0,0 +1,151 @@
> +/*
> + * 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);
> +
> + return sprintf(buf, "%s\n", rproc->firmware);
> +}
> +
> +/* 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);
> + char *p;
> + int err, len = count;
> +
> + err = mutex_lock_interruptible(&rproc->lock);
> + if (err) {
> + dev_err(dev, "can't lock rproc %s: %d\n", rproc->name, err);
> + return -EINVAL;
> + }
> +
> + if (rproc->state != RPROC_OFFLINE) {
> + dev_err(dev, "can't change firmware while running\n");
> + err = -EBUSY;
> + goto out;
> + }
> +
> + len = strcspn(buf, "\n");
> +
> + p = kstrndup(buf, len, GFP_KERNEL);
> + if (!p) {
> + err = -ENOMEM;
> + goto out;
> + }
> +
> + kfree(rproc->firmware);
it gives me kernel panic if the initial firmware name is passed from
my remoteproc driver to rproc_alloc()
and it is a const string.
It is better to have another modification to the remoteproc_core.c as
follows in the rproc_alloc().

- if (!firmware)
+ if (!firmware) {
/*
* Make room for default firmware name (minus %s plus '\0').
* If the caller didn't pass in a firmware name then
@@ -1332,17 +1346,29 @@ struct rproc *rproc_alloc(struct device *dev,
const char *name,
* the caller doesn't pass one).
*/
name_len = strlen(name) + strlen(template) - 2 + 1;
+ p = kmalloc_track_caller(name_len, GFP_KERNEL);
+ if (!p)
+ return NULL;
+ snprintf(p, name_len, template, name);
+ } else {
+ p = kstrndup(firmware, strlen(firmware), GFP_KERNEL);
+ if (!p) {
+ return NULL;
+ }
+ }

- rproc = kzalloc(sizeof(*rproc) + len + name_len, GFP_KERNEL);
+ rproc = kzalloc(sizeof(*rproc) + len, GFP_KERNEL);

> + rproc->firmware = p;
> +out:
> + mutex_unlock(&rproc->lock);
> +
> + 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[] = {
> + [RPROC_OFFLINE] = "offline",
> + [RPROC_SUSPENDED] = "suspended",
> + [RPROC_RUNNING] = "running",
> + [RPROC_CRASHED] = "crashed",
> + [RPROC_LAST] = "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 sprintf(buf, "%s\n", rproc_state_string[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;
> +
> + if (sysfs_streq(buf, "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(buf, "stop")) {
> + if (rproc->state != RPROC_RUNNING)
> + return -EINVAL;
> +
> + rproc_shutdown(rproc);
The kernel hanged when it was trying to unregister the virtio device
after I tried"stop".
It doesn't look like related to this sysfs API. But just wonder have you seen
similar issue?

> + } else {
> + dev_err(&rproc->dev, "Unrecognised option: %s\n", buf);
> + ret = -EINVAL;
> + }
> + return ret ? ret : count;
> +}
> +static DEVICE_ATTR_RW(state);
> +
> +static 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 = {
> + .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);
> +}
> --
> 2.7.4
>
> --
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