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Message-ID: <CAHp75VeSS+-m=V59Z36n2maGtu499UwuKk=t9VB=JwqqvO=Qaw@mail.gmail.com>
Date: Fri, 27 Nov 2020 16:12:52 +0200
From: Andy Shevchenko <andy.shevchenko@...il.com>
To: Alexandru Ardelean <alexandru.ardelean@...log.com>
Cc: linux-spi <linux-spi@...r.kernel.org>,
devicetree <devicetree@...r.kernel.org>,
Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
Rob Herring <robh+dt@...nel.org>,
Mark Brown <broonie@...nel.org>,
"Bogdan, Dragos" <dragos.bogdan@...log.com>
Subject: Re: [PATCH v3 1/3] spi: uapi: unify SPI modes into a single spi.h header
On Fri, Nov 27, 2020 at 3:08 PM Alexandru Ardelean
<alexandru.ardelean@...log.com> wrote:
>
> This change moves all the SPI mode bits into a separate 'spi.h' header in
> uapi. This is meant to re-use these definitions inside the kernel as well
> as export them to userspace (via uapi).
uapi -> UAPI (or uAPI) here and everywhere else where it makes sense.
> The SPI mode definitions have usually been duplicated between between
> 'include/linux/spi/spi.h' and 'include/uapi/linux/spi/spidev.h', so
> whenever adding a new entry, this would need to be put in both headers.
>
> They've been moved from 'include/linux/spi/spi.h', since that seems a bit
> more complete; the bits have descriptions and there is the SPI_MODE_X_MASK.
>
> For now, this change does a simple move; no conversions to BIT() macros are
> being done at this point. This can be done later, as that requires also
> another header inclusion (the 'const.h' header).
> The change as-is makes this 'spi.h' header more standalone.
>
> Signed-off-by: Alexandru Ardelean <alexandru.ardelean@...log.com>
> ---
>
> Personally, I am not sure whether to convert the bitfield tos _BITUL()
> macros or not. I feel that not-having these macros makes this uapi spi.h
> header more standalone.
> If there's a strong insistence to use those _BITUL() macros, I'll do it.
> I'm hesitant now, because it requires that this spi.h includes the
> 'const.h' header.
_BITUL is a part of uAPI, why not to use it?
In general BIT() type of macros makes values easier to read and less
error prone (in big numbers it's easy to miss 0).
It's not a strong opinion, it's just the rationale behind how I see it.
> Changelog v2 -> v3:
> * https://lore.kernel.org/linux-spi/20201124102152.16548-1-alexandru.ardelean@analog.com/
> * dropped 'spi: convert to BIT() all spi_device flags '
> added 'spi: uapi: unify SPI modes into a single spi.h header'
>
> include/linux/spi/spi.h | 22 +--------------
> include/uapi/linux/spi/spi.h | 47 +++++++++++++++++++++++++++++++++
> include/uapi/linux/spi/spidev.h | 30 +--------------------
> 3 files changed, 49 insertions(+), 50 deletions(-)
> create mode 100644 include/uapi/linux/spi/spi.h
>
> diff --git a/include/linux/spi/spi.h b/include/linux/spi/spi.h
> index aa09fdc8042d..a4fedb33d34b 100644
> --- a/include/linux/spi/spi.h
> +++ b/include/linux/spi/spi.h
> @@ -14,6 +14,7 @@
> #include <linux/scatterlist.h>
> #include <linux/gpio/consumer.h>
> #include <linux/ptp_clock_kernel.h>
> +#include <uapi/linux/spi/spi.h>
>
> struct dma_chan;
> struct property_entry;
> @@ -165,27 +166,6 @@ struct spi_device {
> u8 bits_per_word;
> bool rt;
> u32 mode;
> -#define SPI_CPHA 0x01 /* clock phase */
> -#define SPI_CPOL 0x02 /* clock polarity */
> -#define SPI_MODE_0 (0|0) /* (original MicroWire) */
> -#define SPI_MODE_1 (0|SPI_CPHA)
> -#define SPI_MODE_2 (SPI_CPOL|0)
> -#define SPI_MODE_3 (SPI_CPOL|SPI_CPHA)
> -#define SPI_MODE_X_MASK (SPI_CPOL|SPI_CPHA)
> -#define SPI_CS_HIGH 0x04 /* chipselect active high? */
> -#define SPI_LSB_FIRST 0x08 /* per-word bits-on-wire */
> -#define SPI_3WIRE 0x10 /* SI/SO signals shared */
> -#define SPI_LOOP 0x20 /* loopback mode */
> -#define SPI_NO_CS 0x40 /* 1 dev/bus, no chipselect */
> -#define SPI_READY 0x80 /* slave pulls low to pause */
> -#define SPI_TX_DUAL 0x100 /* transmit with 2 wires */
> -#define SPI_TX_QUAD 0x200 /* transmit with 4 wires */
> -#define SPI_RX_DUAL 0x400 /* receive with 2 wires */
> -#define SPI_RX_QUAD 0x800 /* receive with 4 wires */
> -#define SPI_CS_WORD 0x1000 /* toggle cs after each word */
> -#define SPI_TX_OCTAL 0x2000 /* transmit with 8 wires */
> -#define SPI_RX_OCTAL 0x4000 /* receive with 8 wires */
> -#define SPI_3WIRE_HIZ 0x8000 /* high impedance turnaround */
> int irq;
> void *controller_state;
> void *controller_data;
> diff --git a/include/uapi/linux/spi/spi.h b/include/uapi/linux/spi/spi.h
> new file mode 100644
> index 000000000000..ae028d64c779
> --- /dev/null
> +++ b/include/uapi/linux/spi/spi.h
> @@ -0,0 +1,47 @@
> +/* SPDX-License-Identifier: GPL-2.0+ WITH Linux-syscall-note */
> +/*
> + * include/linux/spi/spi.h
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License as published by
> + * the Free Software Foundation; either version 2 of the License, or
> + * (at your option) any later version.
> + *
> + * 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.
> + *
> + * You should have received a copy of the GNU General Public License
> + * along with this program; if not, write to the Free Software
> + * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
> + */
Do we still need this boilerplate license header?
> +
> +#ifndef _UAPI_SPI_H
> +#define _UAPI_SPI_H
> +
> +#define SPI_CPHA 0x01 /* clock phase */
> +#define SPI_CPOL 0x02 /* clock polarity */
> +
> +#define SPI_MODE_0 (0|0) /* (original MicroWire) */
> +#define SPI_MODE_1 (0|SPI_CPHA)
> +#define SPI_MODE_2 (SPI_CPOL|0)
> +#define SPI_MODE_3 (SPI_CPOL|SPI_CPHA)
> +#define SPI_MODE_X_MASK (SPI_CPOL|SPI_CPHA)
> +
> +#define SPI_CS_HIGH 0x04 /* chipselect active high? */
> +#define SPI_LSB_FIRST 0x08 /* per-word bits-on-wire */
> +#define SPI_3WIRE 0x10 /* SI/SO signals shared */
> +#define SPI_LOOP 0x20 /* loopback mode */
> +#define SPI_NO_CS 0x40 /* 1 dev/bus, no chipselect */
> +#define SPI_READY 0x80 /* slave pulls low to pause */
> +#define SPI_TX_DUAL 0x100 /* transmit with 2 wires */
> +#define SPI_TX_QUAD 0x200 /* transmit with 4 wires */
> +#define SPI_RX_DUAL 0x400 /* receive with 2 wires */
> +#define SPI_RX_QUAD 0x800 /* receive with 4 wires */
> +#define SPI_CS_WORD 0x1000 /* toggle cs after each word */
> +#define SPI_TX_OCTAL 0x2000 /* transmit with 8 wires */
> +#define SPI_RX_OCTAL 0x4000 /* receive with 8 wires */
> +#define SPI_3WIRE_HIZ 0x8000 /* high impedance turnaround */
> +
> +#endif /* _UAPI_SPI_H */
> diff --git a/include/uapi/linux/spi/spidev.h b/include/uapi/linux/spi/spidev.h
> index d56427c0b3e0..0c3da08f2aff 100644
> --- a/include/uapi/linux/spi/spidev.h
> +++ b/include/uapi/linux/spi/spidev.h
> @@ -25,35 +25,7 @@
>
> #include <linux/types.h>
> #include <linux/ioctl.h>
> -
> -/* User space versions of kernel symbols for SPI clocking modes,
> - * matching <linux/spi/spi.h>
> - */
> -
> -#define SPI_CPHA 0x01
> -#define SPI_CPOL 0x02
> -
> -#define SPI_MODE_0 (0|0)
> -#define SPI_MODE_1 (0|SPI_CPHA)
> -#define SPI_MODE_2 (SPI_CPOL|0)
> -#define SPI_MODE_3 (SPI_CPOL|SPI_CPHA)
> -
> -#define SPI_CS_HIGH 0x04
> -#define SPI_LSB_FIRST 0x08
> -#define SPI_3WIRE 0x10
> -#define SPI_LOOP 0x20
> -#define SPI_NO_CS 0x40
> -#define SPI_READY 0x80
> -#define SPI_TX_DUAL 0x100
> -#define SPI_TX_QUAD 0x200
> -#define SPI_RX_DUAL 0x400
> -#define SPI_RX_QUAD 0x800
> -#define SPI_CS_WORD 0x1000
> -#define SPI_TX_OCTAL 0x2000
> -#define SPI_RX_OCTAL 0x4000
> -#define SPI_3WIRE_HIZ 0x8000
> -
> -/*---------------------------------------------------------------------------*/
> +#include <linux/spi/spi.h>
>
> /* IOCTL commands */
>
> --
> 2.27.0
>
--
With Best Regards,
Andy Shevchenko
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