[PATCH 07/29] remoteproc.txt: standardize document format

Mauro Carvalho Chehab
2017-05-19T01:26:58Z

- mark document and section titles;
- adjust identation;
- mark literal blocks

Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
---
Documentation/remoteproc.txt | 320 +++++++++++++++++++++++++------------------
1 file changed, 185 insertions(+), 135 deletions(-)

diff --git a/Documentation/remoteproc.txt b/Documentation/remoteproc.txt
index f07597482351..77fb03acdbb4 100644
--- a/Documentation/remoteproc.txt
+++ b/Documentation/remoteproc.txt
@@ -1,6 +1,9 @@
+==========================
Remote Processor Framework
+==========================

-1. Introduction
+Introduction
+============

Modern SoCs typically have heterogeneous remote processor devices in asymmetric
multiprocessing (AMP) configurations, which may be running different instances
@@ -26,44 +29,62 @@ remoteproc will add those devices. This makes it possible to reuse the
existing virtio drivers with remote processor backends at a minimal development
cost.

-2. User API
+User API
+========
+
+::

int rproc_boot(struct rproc *rproc)
- - Boot a remote processor (i.e. load its firmware, power it on, ...).
- If the remote processor is already powered on, this function immediately
- returns (successfully).
- Returns 0 on success, and an appropriate error value otherwise.
- Note: to use this function you should already have a valid rproc
- handle. There are several ways to achieve that cleanly (devres, pdata,
- the way remoteproc_rpmsg.c does this, or, if this becomes prevalent, we
- might also consider using dev_archdata for this).
+
+Boot a remote processor (i.e. load its firmware, power it on, ...).
+
+If the remote processor is already powered on, this function immediately
+returns (successfully).
+
+Returns 0 on success, and an appropriate error value otherwise.
+Note: to use this function you should already have a valid rproc
+handle. There are several ways to achieve that cleanly (devres, pdata,
+the way remoteproc_rpmsg.c does this, or, if this becomes prevalent, we
+might also consider using dev_archdata for this).
+
+::

void rproc_shutdown(struct rproc *rproc)
- - Power off a remote processor (previously booted with rproc_boot()).
- In case @rproc is still being used by an additional user(s), then
- this function will just decrement the power refcount and exit,
- without really powering off the device.
- Every call to rproc_boot() must (eventually) be accompanied by a call
- to rproc_shutdown(). Calling rproc_shutdown() redundantly is a bug.
- Notes:
- - we're not decrementing the rproc's refcount, only the power refcount.
- which means that the @rproc handle stays valid even after
- rproc_shutdown() returns, and users can still use it with a subsequent
- rproc_boot(), if needed.
+
+Power off a remote processor (previously booted with rproc_boot()).
+In case @rproc is still being used by an additional user(s), then
+this function will just decrement the power refcount and exit,
+without really powering off the device.
+
+Every call to rproc_boot() must (eventually) be accompanied by a call
+to rproc_shutdown(). Calling rproc_shutdown() redundantly is a bug.
+
+.. note::
+
+ we're not decrementing the rproc's refcount, only the power refcount.
+ which means that the @rproc handle stays valid even after
+ rproc_shutdown() returns, and users can still use it with a subsequent
+ rproc_boot(), if needed.
+
+::

struct rproc *rproc_get_by_phandle(phandle phandle)
- - Find an rproc handle using a device tree phandle. Returns the rproc
- handle on success, and NULL on failure. This function increments
- the remote processor's refcount, so always use rproc_put() to
- decrement it back once rproc isn't needed anymore.

-3. Typical usage
+Find an rproc handle using a device tree phandle. Returns the rproc
+handle on success, and NULL on failure. This function increments
+the remote processor's refcount, so always use rproc_put() to
+decrement it back once rproc isn't needed anymore.

-#include <linux/remoteproc.h>
+Typical usage
+=============

-/* in case we were given a valid 'rproc' handle */
-int dummy_rproc_example(struct rproc *my_rproc)
-{
+::
+
+ #include <linux/remoteproc.h>
+
+ /* in case we were given a valid 'rproc' handle */
+ int dummy_rproc_example(struct rproc *my_rproc)
+ {
int ret;

/* let's power on and boot our remote processor */
@@ -80,84 +101,111 @@ int dummy_rproc_example(struct rproc *my_rproc)

/* let's shut it down now */
rproc_shutdown(my_rproc);
-}
+ }

-4. API for implementors
+API for implementors
+====================
+
+::

struct rproc *rproc_alloc(struct device *dev, const char *name,
const struct rproc_ops *ops,
const char *firmware, int len)
- - Allocate a new remote processor handle, but don't register
- it yet. Required parameters are the underlying device, the
- name of this remote processor, platform-specific ops handlers,
- the name of the firmware to boot this rproc with, and the
- length of private data needed by the allocating rproc driver (in bytes).
-
- This function should be used by rproc implementations during
- initialization of the remote processor.
- After creating an rproc handle using this function, and when ready,
- implementations should then call rproc_add() to complete
- the registration of the remote processor.
- On success, the new rproc is returned, and on failure, NULL.
-
- Note: _never_ directly deallocate @rproc, even if it was not registered
- yet. Instead, when you need to unroll rproc_alloc(), use rproc_free().
+
+Allocate a new remote processor handle, but don't register
+it yet. Required parameters are the underlying device, the
+name of this remote processor, platform-specific ops handlers,
+the name of the firmware to boot this rproc with, and the
+length of private data needed by the allocating rproc driver (in bytes).
+
+This function should be used by rproc implementations during
+initialization of the remote processor.
+
+After creating an rproc handle using this function, and when ready,
+implementations should then call rproc_add() to complete
+the registration of the remote processor.
+
+On success, the new rproc is returned, and on failure, NULL.
+
+.. note::
+
+ **never** directly deallocate @rproc, even if it was not registered
+ yet. Instead, when you need to unroll rproc_alloc(), use rproc_free().
+
+::

void rproc_free(struct rproc *rproc)
- - Free an rproc handle that was allocated by rproc_alloc.
- This function essentially unrolls rproc_alloc(), by decrementing the
- rproc's refcount. It doesn't directly free rproc; that would happen
- only if there are no other references to rproc and its refcount now
- dropped to zero.
+
+Free an rproc handle that was allocated by rproc_alloc.
+
+This function essentially unrolls rproc_alloc(), by decrementing the
+rproc's refcount. It doesn't directly free rproc; that would happen
+only if there are no other references to rproc and its refcount now
+dropped to zero.
+
+::

int rproc_add(struct rproc *rproc)
- - Register @rproc with the remoteproc framework, after it has been
- allocated with rproc_alloc().
- This is called by the platform-specific rproc implementation, whenever
- a new remote processor device is probed.
- Returns 0 on success and an appropriate error code otherwise.
- Note: this function initiates an asynchronous firmware loading
- context, which will look for virtio devices supported by the rproc's
- firmware.
- If found, those virtio devices will be created and added, so as a result
- of registering this remote processor, additional virtio drivers might get
- probed.
+
+Register @rproc with the remoteproc framework, after it has been
+allocated with rproc_alloc().
+
+This is called by the platform-specific rproc implementation, whenever
+a new remote processor device is probed.
+
+Returns 0 on success and an appropriate error code otherwise.
+Note: this function initiates an asynchronous firmware loading
+context, which will look for virtio devices supported by the rproc's
+firmware.
+
+If found, those virtio devices will be created and added, so as a result
+of registering this remote processor, additional virtio drivers might get
+probed.
+
+::

int rproc_del(struct rproc *rproc)
- - Unroll rproc_add().
- This function should be called when the platform specific rproc
- implementation decides to remove the rproc device. it should
- _only_ be called if a previous invocation of rproc_add()
- has completed successfully.

- After rproc_del() returns, @rproc is still valid, and its
- last refcount should be decremented by calling rproc_free().
+Unroll rproc_add().

- Returns 0 on success and -EINVAL if @rproc isn't valid.
+This function should be called when the platform specific rproc
+implementation decides to remove the rproc device. it should
+_only_ be called if a previous invocation of rproc_add()
+has completed successfully.
+
+After rproc_del() returns, @rproc is still valid, and its
+last refcount should be decremented by calling rproc_free().
+
+Returns 0 on success and -EINVAL if @rproc isn't valid.
+
+::

void rproc_report_crash(struct rproc *rproc, enum rproc_crash_type type)
- - Report a crash in a remoteproc
- This function must be called every time a crash is detected by the
- platform specific rproc implementation. This should not be called from a
- non-remoteproc driver. This function can be called from atomic/interrupt
- context.

-5. Implementation callbacks
+Report a crash in a remoteproc
+
+This function must be called every time a crash is detected by the
+platform specific rproc implementation. This should not be called from a
+non-remoteproc driver. This function can be called from atomic/interrupt
+context.
+
+Implementation callbacks
+========================

These callbacks should be provided by platform-specific remoteproc
-drivers:
+drivers::

-/**
- * struct rproc_ops - platform-specific device handlers
- * @start: power on the device and boot it
- * @stop: power off the device
- * @kick: kick a virtqueue (virtqueue id given as a parameter)
- */
-struct rproc_ops {
+ /**
+ * struct rproc_ops - platform-specific device handlers
+ * @start: power on the device and boot it
+ * @stop: power off the device
+ * @kick: kick a virtqueue (virtqueue id given as a parameter)
+ */
+ struct rproc_ops {
int (*start)(struct rproc *rproc);
int (*stop)(struct rproc *rproc);
void (*kick)(struct rproc *rproc, int vqid);
-};
+ };

Every remoteproc implementation should at least provide the ->start and ->stop
handlers. If rpmsg/virtio functionality is also desired, then the ->kick handler
@@ -179,7 +227,8 @@ the exact virtqueue index to look in is optional: it is easy (and not
too expensive) to go through the existing virtqueues and look for new buffers
in the used rings.

-6. Binary Firmware Structure
+Binary Firmware Structure
+=========================

At this point remoteproc only supports ELF32 firmware binaries. However,
it is quite expected that other platforms/devices which we'd want to
@@ -207,43 +256,43 @@ resource entries that publish the existence of supported features
or configurations by the remote processor, such as trace buffers and
supported virtio devices (and their configurations).

-The resource table begins with this header:
+The resource table begins with this header::

-/**
- * struct resource_table - firmware resource table header
- * @ver: version number
- * @num: number of resource entries
- * @reserved: reserved (must be zero)
- * @offset: array of offsets pointing at the various resource entries
- *
- * The header of the resource table, as expressed by this structure,
- * contains a version number (should we need to change this format in the
- * future), the number of available resource entries, and their offsets
- * in the table.
- */
-struct resource_table {
+ /**
+ * struct resource_table - firmware resource table header
+ * @ver: version number
+ * @num: number of resource entries
+ * @reserved: reserved (must be zero)
+ * @offset: array of offsets pointing at the various resource entries
+ *
+ * The header of the resource table, as expressed by this structure,
+ * contains a version number (should we need to change this format in the
+ * future), the number of available resource entries, and their offsets
+ * in the table.
+ */
+ struct resource_table {
u32 ver;
u32 num;
u32 reserved[2];
u32 offset[0];
-} __packed;
+ } __packed;

Immediately following this header are the resource entries themselves,
-each of which begins with the following resource entry header:
+each of which begins with the following resource entry header::

-/**
- * struct fw_rsc_hdr - firmware resource entry header
- * @type: resource type
- * @data: resource data
- *
- * Every resource entry begins with a 'struct fw_rsc_hdr' header providing
- * its @type. The content of the entry itself will immediately follow
- * this header, and it should be parsed according to the resource type.
- */
-struct fw_rsc_hdr {
+ /**
+ * struct fw_rsc_hdr - firmware resource entry header
+ * @type: resource type
+ * @data: resource data
+ *
+ * Every resource entry begins with a 'struct fw_rsc_hdr' header providing
+ * its @type. The content of the entry itself will immediately follow
+ * this header, and it should be parsed according to the resource type.
+ */
+ struct fw_rsc_hdr {
u32 type;
u8 data[0];
-} __packed;
+ } __packed;

Some resources entries are mere announcements, where the host is informed
of specific remoteproc configuration. Other entries require the host to
@@ -252,32 +301,32 @@ is expected, where the firmware requests a resource, and once allocated,
the host should provide back its details (e.g. address of an allocated
memory region).

-Here are the various resource types that are currently supported:
+Here are the various resource types that are currently supported::

-/**
- * enum fw_resource_type - types of resource entries
- *
- * @RSC_CARVEOUT: request for allocation of a physically contiguous
- * memory region.
- * @RSC_DEVMEM: request to iommu_map a memory-based peripheral.
- * @RSC_TRACE: announces the availability of a trace buffer into which
- * the remote processor will be writing logs.
- * @RSC_VDEV: declare support for a virtio device, and serve as its
- * virtio header.
- * @RSC_LAST: just keep this one at the end
- *
- * Please note that these values are used as indices to the rproc_handle_rsc
- * lookup table, so please keep them sane. Moreover, @RSC_LAST is used to
- * check the validity of an index before the lookup table is accessed, so
- * please update it as needed.
- */
-enum fw_resource_type {
+ /**
+ * enum fw_resource_type - types of resource entries
+ *
+ * @RSC_CARVEOUT: request for allocation of a physically contiguous
+ * memory region.
+ * @RSC_DEVMEM: request to iommu_map a memory-based peripheral.
+ * @RSC_TRACE: announces the availability of a trace buffer into which
+ * the remote processor will be writing logs.
+ * @RSC_VDEV: declare support for a virtio device, and serve as its
+ * virtio header.
+ * @RSC_LAST: just keep this one at the end
+ *
+ * Please note that these values are used as indices to the rproc_handle_rsc
+ * lookup table, so please keep them sane. Moreover, @RSC_LAST is used to
+ * check the validity of an index before the lookup table is accessed, so
+ * please update it as needed.
+ */
+ enum fw_resource_type {
RSC_CARVEOUT = 0,
RSC_DEVMEM = 1,
RSC_TRACE = 2,
RSC_VDEV = 3,
RSC_LAST = 4,
-};
+ };

For more details regarding a specific resource type, please see its
dedicated structure in include/linux/remoteproc.h.
@@ -286,7 +335,8 @@ We also expect that platform-specific resource entries will show up
at some point. When that happens, we could easily add a new RSC_PLATFORM
type, and hand those resources to the platform-specific rproc driver to handle.

-7. Virtio and remoteproc
+Virtio and remoteproc
+=====================

The firmware should provide remoteproc information about virtio devices
that it supports, and their configurations: a RSC_VDEV resource entry
--
2.9.4