[PATCH] bsps/shared/ofw: Added and Documented RTEMS OFW interface

Thu Aug 13 05:05:12 UTC 2020

On Thu, Aug 13, 2020 at 12:36 AM Gedare Bloom <gedare at rtems.org> wrote:

> I make a few comments below for you to consider. At a high level, I
> think the interface looks reasonable, although plainly mimics the
> freebsd naming conventions. I wonder if we should prefer our naming
> conventions, which is to aim to use _ to separate different words, and
> to limit use of abbreviations except as they help shorten very long
> names?
>
> I might suggest something along these lines:
> rtems_ofw_get_prop_len() instead of rtems_ofw_getproplen() for example.
>

I'll change them to RTEMS naming conventions.

>
> It will make mapping to FreeBSD a little more annoying, but will make
> the RTEMS interface more RTEMS-friendly.
>
> Other small comments below.
>
> On Wed, Aug 12, 2020 at 10:11 AM G S Niteesh Babu <niteesh.gs at gmail.com>
> wrote:
> >
> > ---
> >  bsps/shared/dev/ofw/ofw.c |   0
> >  bsps/shared/dev/ofw/ofw.h | 437 ++++++++++++++++++++++++++++++++++++++
> >  2 files changed, 437 insertions(+)
> >  create mode 100644 bsps/shared/dev/ofw/ofw.c
> >  create mode 100644 bsps/shared/dev/ofw/ofw.h
> >
> > diff --git a/bsps/shared/dev/ofw/ofw.c b/bsps/shared/dev/ofw/ofw.c
> > new file mode 100644
> > index 0000000000..e69de29bb2
> > diff --git a/bsps/shared/dev/ofw/ofw.h b/bsps/shared/dev/ofw/ofw.h
> > new file mode 100644
> > index 0000000000..5a8526c892
> > --- /dev/null
> > +++ b/bsps/shared/dev/ofw/ofw.h
> > @@ -0,0 +1,437 @@
> > +/* SPDX-License-Identifier: BSD-2-Clause */
> > +
> > +/**
> > + * @file
> > + *
> > + * @ingroup ofw
> > + *
> > + * RTEMS FDT implementation of OpenFirmWare Interface.
> > + */
> > +
> > +/*
> > + * Copyright (C) <2020> Niteesh Babu G S <niteesh.gs at gmail.com>
>
> no <> around year
>
Fixed.

>
> > + *
> > + * Redistribution and use in source and binary forms, with or without
> > + * modification, are permitted provided that the following conditions
> > + * are met:
> > + * 1. Redistributions of source code must retain the above copyright
> > + *    notice, this list of conditions and the following disclaimer.
> > + * 2. Redistributions in binary form must reproduce the above copyright
> > + *    notice, this list of conditions and the following disclaimer in
> the
> > + *    documentation and/or other materials provided with the
> distribution.
> > + *
> > + * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
> "AS IS"
> > + * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
> TO, THE
> > + * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
> PURPOSE
> > + * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
> CONTRIBUTORS BE
> > + * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
> > + * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
> > + * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
> BUSINESS
> > + * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER
> IN
> > + * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
> OTHERWISE)
> > + * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
> OF THE
> > + * POSSIBILITY OF SUCH DAMAGE.
> > + */
> > +
> > +#ifndef _OFW_H
> > +#define _OFW_H
> > +
> > +#ifdef __cplusplus
> > +extern "C" {
> > +#endif
> > +
> > +#include <stdint.h>
> > +#include <stddef.h>
> > +
> > +typedef uint32_t  ihandle_t;
> > +typedef uint32_t  pcell_t;
> > +typedef uint32_t  phandle_t;
> document the types?
>
I'll document them. I should document their use right? Like what
ihandle_t, phandle_t represent.

> +
> > +/**
> > + * @brief Gets the node that is next to @a node.
>
> Somewhere the data structure should be explained. Maybe it will take a
> new section in our doco to document the new interface.
>

Once we finalize the interface. I'll add it to the doco.
But I don't understand what you mean by data structures.

> > + *
> > + * @param[in] node Node offset
> > + *
> > + * @retval Peer node offset Successful operation.
> > + * @retval 0 No peer node or invalid node handle
> > + */
> > +phandle_t rtems_ofw_peer(
> > +  phandle_t   node
> > +);
> > +
> > +/**
> > + * @brief Gets the node that is the child of @a node.
> > + *
> > + * @param[in] node Node offset
> > + *
> > + * @retval child node offset Successful operation.
> > + * @retval 0 No child node or invalid node handle
> > + */
> > +phandle_t rtems_ofw_child(
> > +  phandle_t   node
> > +);
> > +
> > +/**
> > + * @brief Gets the node that is the parent of @a node.
> > + *
> > + * @param[in] node Node offset
> > + *
> > + * @retval child node offset Successful operation.
> > + * @retval 0 No child node or invalid node handle
> > + */
> > +phandle_t rtems_ofw_parent(
> > +  phandle_t   node
> > +);
> > +
> > +/**
> > + * @brief Gets the length of the property mentioned in @a propname.
> > + *
> > + * @param[in] node Node offset
> > + * @param[in] prop Property name
> > + *
> > + * @retval -1 Invalid node or property
> > + * @retval  Length of property on successful operation
> > + */
> > +size_t rtems_ofw_getproplen(
> > +  phandle_t   node,
> > +  const char *propname
> > +);
> > +
> > +
> 1 blank
>
Fixed.

>
> > +/**
> > + * @brief Gets the value of property mentioned in @a propname.
> > + *
> > + * @param[in] node Node offset
> > + * @param[in] prop Property name
> > + * @param[out] buf The property value gets stored in this buffer
> (Pre-allocated)
> > + * @param[in] len Length of the buffer
> > +
> > + * @retval -1 Invalid node or property
> > + * @retval  Length of property on successful operation
> > + */
> > +size_t rtems_ofw_getprop(
> > +  phandle_t    node,
> > +  const char  *propname,
> > +  void        *buf,
> > +  size_t       len
> > +);
> > +
> > +/**
> > + * @brief Gets the value of property mentioned in @a propname.
> prop
>
Fixed.

>
> > + *
> > + * Gets the value of property of @a node and converts the value into
> the host's
> > + * endiannes.
> > + *
> > + * @param[in] node Node offset
> > + * @param[in] prop Property name
> > + * @param[out] buf The property value gets stored in this
> buffer(Pre-allocated)
> > + * after converted to the host's endiannes
> typo: endianness
> more misspelled below
>
Sorry for the typo. I fixed them all.

>
> > + * @param[in] len Length of the buffer
> > + *
> > + * @retval -1 Invalid node or property
> > + * @retval  Length of property on successful operation
> > + */
> > +size_t rtems_ofw_getencprop(
> > +  phandle_t    node,
> > +  const char  *prop,
> > +  pcell_t     *buf,
> > +  size_t       len
> > +);
> > +
> > +/**
> > + * @brief Checks if the property @a propname is present in @a node.
> > + *
> > + * @param[in] node Node offset
> > + * @param[in] propname Property name
> > + *
> > + *  @retval  0 Property not present.
> > + *  @retval  1 Property is present.
> > + */
> > +int rtems_ofw_hasprop(
> > +  phandle_t    node,
> > +  const char  *propname
> > +);
> > +
> > +/**
> > + * @brief Searches for property @a propname in @a node.
> > + *
> > + * Searches the node and its parent recursively for the property and
> fills the
> > + * buffer with the first found value.
> > + *
> > + * @param[in] node Node offset
> > + * @param[in] propname Property name
> > + * @param[out] buf The property value gets stored in this buffer
> (Pre-allocated)
> > + * @param[in] len Length of the buffer
> > + *
> > + * @retval  Length of the property if property is found.
> > + * @retval  -1 Property is not found.
> > + */
> > +size_t rtems_ofw_searchprop(
> > +  phandle_t    node,
> > +  const char  *propname,
> > +  void        *buf,
> > +  size_t       len
> > +);
> > +
> > +/**
> > + * @brief Searches for property @a propname in @a node.
> > + *
> > + * Searches the node and its parent recursively for the property and
> fills the
> > + * buffer with the first value found after converting it to the
> endiannes of the
> > + * host.
> > + *
> > + * @param[in] node Node offset
> > + * @param[in] propname Property name
> > + * @param[out] buf The property value gets stored in this
> buffer(Pre-allocated)
> > + * after converted to the host's endiannes
> > + * @param[in] len Length of the buffer
> > + *
> > + * @retval  Length of the property if property is found.
> > + * @retval  -1 Property is not found.
> > + */
> > +size_t rtems_ofw_searchencprop(
> > +  phandle_t    node,
> > +  const char  *propname,
> > +  pcell_t     *buf,
> > +  size_t       len
> > +);
> > +
> > +/**
> > + * @brief Gets the value of property mentioned in @a propname.
> > + *
> > + * Same as rtems_ofw_getprop, but the @a buf is allocated in this
> routine and
> > + * the user is responsible for freeing it.
> > + *
> > + * @param[in] node Node offset
> > + * @param[in] propname Property name
> > + * @param[out] buf The buffer is allocated in this routine and user is
> > + * responsible for freeing.
> > + *
> > + * @retval  -1 Property is not found.
> > + * @retval  Length of the property if property is found.
> > + */
> > +size_t rtems_ofw_getprop_alloc(
> > +  phandle_t    node,
> > +  const char  *propname,
> > +  void       **buf
> > +);
> > +
> > +/**
> > + * @brief Gets multiple values of the property @a propname.
> > + *
> > + * Same as rtems_ofw_getprop_alloc but it can read properties with
> multiple
> > + * values.
> > + * For eg: reg = <0x1000 0x10 0x2000 0x20>
> > + *
> > + * @param[in] node Node offset
> > + * @param[in] propname Property name
> > + * @param[in] elsz Size of the single value
> > + * @param[out] buf The buffer is allocated in this routine and user is
> > + * responsible for freeing.
> > + *
> > + * @retval  -1 Property is not found.
> > + * @retval   Number of values read.
> > + */
> > +size_t rtems_ofw_getprop_alloc_multi(
> > +  phandle_t    node,
> > +  const char  *propname,
> > +  int          elsz,
> > +  void       **buf
> > +);
> > +
> > +/**
> > + * @brief Gets the value of property mentioned in @a propname.
> > + *
> > + * Same as rtems_ofw_getprop_alloc but the value stored in the buffer is
> > + * converted into the host's endiannes.
> > + *
> > + * @param[in] node Node offset
> > + * @param[in] propname Property name
> > + * @param[out] buf The buffer is allocated in this routine and user is
> > + * responsible for freeing.
> > + *
> > + * @retval  -1 Property is not found.
> > + * @retval  Length of the property if property is found.
> > + */
> > +size_t rtems_ofw_getencprop_alloc(
> > +  phandle_t    node,
> > +  const char  *propname,
> > +  void       **buf
> > +);
> > +
> > +/**
> > + * @brief Gets multiple values of the property @a propname.
> > + *
> > + * Same as rtems_ofw_getprop_alloc_multi but the values stored in the
> buffer
> > + * are converted to the host's endiannes.
> > + *
> > + * @param[in] node Node offset
> > + * @param[in] propname Property name
> > + * @param[in] elsz Size of the single value
> > + * @param[out] buf The buffer is allocated in this routine and user is
> > + * responsible for freeing.
> must they call rtems_ofw_prop_free?
>

FreeBSD has an OF_free which call's free with proper flags.
In RTEMS we decided to ignore the flags and I blindly copied the
whole interface. So I don't think a separate function for free is
needed but it will make the API uniform.

> > + *
> > + * @retval  -1 Property is not found.
> > + * @retval   Number of values read.
> > + */
> > +size_t rtems_ofw_getencprop_alloc_multi(
> > +  phandle_t     node,
> > +  const char   *propname,
> > +  int           elsz,
> > +  void        **buf
> > +);
> > +
> > +/**
> > + * @brief Free's the buffers allocated by the rtems_ofw_*_alloc
> functions.
> > + *
> > + * @param[in] buf Buffer to be freed
> > + */
> > +void rtems_ofw_prop_free(
> > +  void   *buf
> > +);
> > +
> > +/**
> > + * @brief Finds the next property of @a node.
> > + *
> > + * Finds the next property of the node and when @a propname is NULL it
> returns
> > + * the value in the first property.
> > + *
> > + * @param[in] node Node offset
> > + * @param[in] propname Property name
> > + * @param[out] buf The value of the next property gets stored in this
> buffer
> > + * (Pre-allocated)
> > + * @param[in] len Length of the buffer
> > + *
> > + * @retval  -1 node or previous property does not exist
> > + * @retval   0 no more properties
> > + * @retval   1 success
> > + */
> > +int rtems_ofw_nextprop(
> > +  phandle_t    node,
> > +  const char  *propname,
> > +  char        *buf,
> > +  size_t       len
> > +);
> > +
> > +/**
> > + * @brief Sets the property @name of @a node to @a buf.
> > + *
> > + * @param[in] node Node offset
> > + * @param[in] name Property name
> > + * @param[in] buf Buffer containes the value to be set.
> typo; contains
>
Fixed.

> > + * @param[in] len Length of the buffer
> > + *
> > + * @retval  -1 node does not exist
> > + * @retval   0 on success
> > + * @retval   libFDT error codes on unsuccessful setting operation
> > + */
> > +int rtems_ofw_setprop(
> > +  phandle_t    node,
> > +  const char  *name,
> > +  const void  *buf,
> > +  size_t       len
> > +);
> > +
> > +/**
> > + * @brief Converts a device specifier to a fully qualified path name.
> > + *
> > + * @param[in] dev device specifier
> > + * @param[out] buf The path is filled into the buffer(Pre-allocated)
> > + * @param[in] length of the buffer
> > + *
> > + * @retval  -1 always. Unimplemented.
> > + */
> > +size_t rtems_ofw_canon(
> > +  const char  *dev,
> > +  char        *buf,
> > +  size_t       len
> > +);
> > +
> > +/**
> > + * @brief Finds the node at the given path
> > + *
> > + * @param[in] path to the node from root
> > + *
> > + * @retval  -1 node does not exist
> > + * @retval   node handle on success
> > + */
> > +phandle_t rtems_ofw_finddevice(
> > +  const char  *path
> > +);
> > +
> > +/**
> > + * @brief This routine converts effective phandle of @a node to node
> offset.
> @a xref?
>
Fixed.

> > + *
> > + * @param[in] xref Node phandle
> > + *
> > + * @retval Node offset on success
> > + * @retval Node phandle on failure
> > + */
> > +phandle_t rtems_ofw_node_from_xref(
> > +  phandle_t   xref
> > +);
> > +
> > +/**
> > + * @brief This routine converts node offset to effective phandle of @a
> node.
> > + *
> > + * @retval Node phandle on success
> > + * @retval Node offset on failure
> > + */
> > +phandle_t rtems_ofw_xref_from_node(
> > +  phandle_t   node
> > +);
> > +
> > +/*
> > + * instance handles(ihandle_t) as same as phandles in the FDT
> implementation
> > + * of OF interface.
> > + */
> stray comments?
>

I'll add these comments to the type's documentation above.

I also wanted to add a few other functions that are nor part
of the OF interface but would be really beneficial for RTEMS.

Can I add the following functions?
1) rtems_ofw_get_reg
2) rtems_ofw_status_okay
3) rtems_ofw_get_interrupts

Since these functions are not part of OFW should I use FDT
instead of OFW in the function names?
eg: rtems_fdt_get_reg

> +
> > +/**
> > + * @brief Converts @a instance handle to phandle.
> > + *
> > + * instance are same as node offsets in FDT.
> > + *
> > + * @param[in] instance Node offset
> > + *
> > + * @retval phandle of node on success.
> > + * @retval instance of node on failure.
> > + */
> > +phandle_t rtems_ofw_instance_to_package(
> > +  ihandle_t   instance
> > +);
> > +
> > +/**
> > + * @brief Find the node's path from phandle.
> > + *
> > + * @param[in] node Node offset
> > + * @param[out] buf Path is filled into this buffer(Pre-allocated).
> > + * @param[in] len Length of the buffer.
> > + *
> > + * @retval -1 always. Unimplemented.
> > + */
> > +size_t rtems_ofw_package_to_path(
> > +  phandle_t   node,
> > +  char       *buf,
> > +  size_t      len
> > +);
> > +
> > +/**
> > + * @brief Find the node's path from ihandle.
> > + *
> > + * @param[in] instance Node offset
> > + * @param[out] buf Path is filled into this buffer(Pre-allocated).
> > + * @param[in] len Length of the buffer.
> > + *
> > + * @retval -1 always. Unimplemented.
> > + */
> > +size_t rtems_ofw_instance_to_path(
> > +  ihandle_t  instance,
> > +  char      *buf,
> > +  size_t     len
> > +);
> > +
> > +#ifdef __cplusplus
> > +}
> > +#endif
> > +
> > +#endif /* _OFW_H */
> > \ No newline at end of file
> > --
> > 2.17.1
> >
>
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