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Subject: Re: [PATCH v2 2/9] rpmsg: Introduce __rpmsg{16|32|64} types
To:     Mathieu Poirier <mathieu.poirier@linaro.org>,
        "ohad@wizery.com" <ohad@wizery.com>,
        "bjorn.andersson@linaro.org" <bjorn.andersson@linaro.org>
CC:     "guennadi.liakhovetski@linux.intel.com" 
        <guennadi.liakhovetski@linux.intel.com>,
        "linux-remoteproc@vger.kernel.org" <linux-remoteproc@vger.kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
References: <20201013232519.1367542-1-mathieu.poirier@linaro.org>
 <20201013232519.1367542-3-mathieu.poirier@linaro.org>
From:   Arnaud POULIQUEN <arnaud.pouliquen@st.com>
Message-ID: <03448851-b959-3f56-5618-d31a7b712392@st.com>
Date:   Wed, 14 Oct 2020 18:31:49 +0200
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Hi Mathieu,

On 10/14/20 1:25 AM, Mathieu Poirier wrote:
> Introduce __rpmsg{16|32|64} types along with byte order conversion
> functions based on an rpmsg_device operation as a foundation to
> make RPMSG modular and transport agnostic.
> 
> Suggested-by: Guennadi Liakhovetski <guennadi.liakhovetski@linux.intel.com>
> Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>
> ---
>  include/linux/rpmsg.h            | 51 ++++++++++++++++++++++++
>  include/linux/rpmsg_byteorder.h  | 67 ++++++++++++++++++++++++++++++++
>  include/uapi/linux/rpmsg_types.h | 11 ++++++
>  3 files changed, 129 insertions(+)
>  create mode 100644 include/linux/rpmsg_byteorder.h
>  create mode 100644 include/uapi/linux/rpmsg_types.h
> 
> diff --git a/include/linux/rpmsg.h b/include/linux/rpmsg.h
> index 9fe1c54ae995..165e4c6d4cd3 100644
> --- a/include/linux/rpmsg.h
> +++ b/include/linux/rpmsg.h
> @@ -17,6 +17,7 @@
>  #include <linux/kref.h>
>  #include <linux/mutex.h>
>  #include <linux/poll.h>
> +#include <linux/rpmsg_byteorder.h>
>  
>  #define RPMSG_ADDR_ANY		0xFFFFFFFF
>  
> @@ -40,6 +41,7 @@ typedef int (*rpmsg_rx_cb_t)(struct rpmsg_device *, void *, int, void *, u32);
>  
>  /**
>   * struct rpmsg_device_ops - indirection table for the rpmsg_device operations
> + * @is_little_endian:	returns true if using little endian byte ordering
>   * @create_ept:		create backend-specific endpoint, required
>   * @announce_create:	announce presence of new channel, optional
>   * @announce_destroy:	announce destruction of channel, optional
> @@ -49,6 +51,7 @@ typedef int (*rpmsg_rx_cb_t)(struct rpmsg_device *, void *, int, void *, u32);
>   * advertise new channels implicitly by creating the endpoints.
>   */
>  struct rpmsg_device_ops {
> +	bool (*is_little_endian)(struct rpmsg_device *rpdev);
>  	struct rpmsg_endpoint *(*create_ept)(struct rpmsg_device *rpdev,
>  					    rpmsg_rx_cb_t cb, void *priv,
>  					    struct rpmsg_channel_info chinfo);
> @@ -129,6 +132,54 @@ struct rpmsg_driver {
>  	int (*callback)(struct rpmsg_device *, void *, int, void *, u32);
>  };
>  
> +static inline u16 rpmsg16_to_cpu(struct rpmsg_device *rpdev, __rpmsg16 val)
> +{
> +	if (!rpdev || !rpdev->ops || !rpdev->ops->is_little_endian)
> +		return __rpmsg16_to_cpu(rpmsg_is_little_endian(), val);
> +	else
> +		return __rpmsg16_to_cpu(rpdev->ops->is_little_endian(rpdev), val);
> +}
> +
> +static inline __rpmsg16 cpu_to_rpmsg16(struct rpmsg_device *rpdev, u16 val)
> +{
> +	if (!rpdev || !rpdev->ops || !rpdev->ops->is_little_endian)
> +		return __cpu_to_rpmsg16(rpmsg_is_little_endian(), val);
> +	else
> +		return __cpu_to_rpmsg16(rpdev->ops->is_little_endian(rpdev), val);
> +}
> +
> +static inline u32 rpmsg32_to_cpu(struct rpmsg_device *rpdev, __rpmsg32 val)
> +{
> +	if (!rpdev || !rpdev->ops || !rpdev->ops->is_little_endian)
> +		return __rpmsg32_to_cpu(rpmsg_is_little_endian(), val);
> +	else
> +		return __rpmsg32_to_cpu(rpdev->ops->is_little_endian(rpdev), val);
> +}
> +
> +static inline __rpmsg32 cpu_to_rpmsg32(struct rpmsg_device *rpdev, u32 val)
> +{
> +	if (!rpdev || !rpdev->ops || !rpdev->ops->is_little_endian)
> +		return __cpu_to_rpmsg32(rpmsg_is_little_endian(), val);
> +	else
> +		return __cpu_to_rpmsg32(rpdev->ops->is_little_endian(rpdev), val);
> +}
> +
> +static inline u64 rpmsg64_to_cpu(struct rpmsg_device *rpdev, __rpmsg64 val)
> +{
> +	if (!rpdev || !rpdev->ops || !rpdev->ops->is_little_endian)
> +		return __rpmsg64_to_cpu(rpmsg_is_little_endian(), val);
> +	else
> +		return __rpmsg64_to_cpu(rpdev->ops->is_little_endian(rpdev), val);
> +}
> +
> +static inline __rpmsg64 cpu_to_rpmsg64(struct rpmsg_device *rpdev, u64 val)
> +{
> +	if (!rpdev || !rpdev->ops || !rpdev->ops->is_little_endian)
> +		return __cpu_to_rpmsg64(rpmsg_is_little_endian(), val);
> +	else
> +		return __cpu_to_rpmsg64(rpdev->ops->is_little_endian(rpdev), val);
> +}
> +
>  #if IS_ENABLED(CONFIG_RPMSG)
>  
>  int register_rpmsg_device(struct rpmsg_device *dev);
> diff --git a/include/linux/rpmsg_byteorder.h b/include/linux/rpmsg_byteorder.h
> new file mode 100644
> index 000000000000..c0f565dbad6d
> --- /dev/null
> +++ b/include/linux/rpmsg_byteorder.h
> @@ -0,0 +1,67 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +/*
> + * Follows implementation found in linux/virtio_byteorder.h
> + */
> +#ifndef _LINUX_RPMSG_BYTEORDER_H
> +#define _LINUX_RPMSG_BYTEORDER_H
> +#include <linux/types.h>
> +#include <uapi/linux/rpmsg_types.h>
> +
> +static inline bool rpmsg_is_little_endian(void)
> +{
> +#ifdef __LITTLE_ENDIAN
> +	return true;
> +#else
> +	return false;
> +#endif
> +}

A suggestion:

static inline bool rpmsg_is_little_endian(void)
#if defined(__BYTE_ORDER)
#  if __BYTE_ORDER == __BIG_ENDIAN
	return true;
#  elif __BYTE_ORDER == __LITTLE_ENDIAN
	return false;
#  else
#    warning "unknown endianess, set to little by default"
	return true;
#  endif
#endif
}

Otherwise

Reviewed-by:  Arnaud Pouliquen <arnaud.pouliquen@st.com>

Thanks,
Arnaud

> +
> +static inline u16 __rpmsg16_to_cpu(bool little_endian, __rpmsg16 val)
> +{
> +	if (little_endian)
> +		return le16_to_cpu((__force __le16)val);
> +	else
> +		return be16_to_cpu((__force __be16)val);
> +}
> +
> +static inline __rpmsg16 __cpu_to_rpmsg16(bool little_endian, u16 val)
> +{
> +	if (little_endian)
> +		return (__force __rpmsg16)cpu_to_le16(val);
> +	else
> +		return (__force __rpmsg16)cpu_to_be16(val);
> +}
> +
> +static inline u32 __rpmsg32_to_cpu(bool little_endian, __rpmsg32 val)
> +{
> +	if (little_endian)
> +		return le32_to_cpu((__force __le32)val);
> +	else
> +		return be32_to_cpu((__force __be32)val);
> +}
> +
> +static inline __rpmsg32 __cpu_to_rpmsg32(bool little_endian, u32 val)
> +{
> +	if (little_endian)
> +		return (__force __rpmsg32)cpu_to_le32(val);
> +	else
> +		return (__force __rpmsg32)cpu_to_be32(val);
> +}
> +
> +static inline u64 __rpmsg64_to_cpu(bool little_endian, __rpmsg64 val)
> +{
> +	if (little_endian)
> +		return le64_to_cpu((__force __le64)val);
> +	else
> +		return be64_to_cpu((__force __be64)val);
> +}
> +
> +static inline __rpmsg64 __cpu_to_rpmsg64(bool little_endian, u64 val)
> +{
> +	if (little_endian)
> +		return (__force __rpmsg64)cpu_to_le64(val);
> +	else
> +		return (__force __rpmsg64)cpu_to_be64(val);
> +}
> +
> +#endif /* _LINUX_RPMSG_BYTEORDER_H */
> diff --git a/include/uapi/linux/rpmsg_types.h b/include/uapi/linux/rpmsg_types.h
> new file mode 100644
> index 000000000000..36e3b9404391
> --- /dev/null
> +++ b/include/uapi/linux/rpmsg_types.h
> @@ -0,0 +1,11 @@
> +/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
> +#ifndef _UAPI_LINUX_RPMSG_TYPES_H
> +#define _UAPI_LINUX_RPMSG_TYPES_H
> +
> +#include <linux/types.h>
> +
> +typedef __u16 __bitwise __rpmsg16;
> +typedef __u32 __bitwise __rpmsg32;
> +typedef __u64 __bitwise __rpmsg64;
> +
> +#endif /* _UAPI_LINUX_RPMSG_TYPES_H */
>