linux-kernel - [PATCH v2 0/3] SuperH DMAC fixes

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Message-Id: <20230527164452.64797-1-contact@artur-rojek.eu>
Date:   Sat, 27 May 2023 18:44:49 +0200
From:   Artur Rojek <contact@...ur-rojek.eu>
To:     Yoshinori Sato <ysato@...rs.sourceforge.jp>,
        Rich Felker <dalias@...c.org>,
        John Paul Adrian Glaubitz <glaubitz@...sik.fu-berlin.de>,
        Geert Uytterhoeven <geert@...ux-m68k.org>
Cc:     Rafael Ignacio Zurita <rafaelignacio.zurita@...il.com>,
        linux-sh@...r.kernel.org, linux-kernel@...r.kernel.org,
        Artur Rojek <contact@...ur-rojek.eu>
Subject: [PATCH v2 0/3] SuperH DMAC fixes

Hi all,

This is v2 of the DMAC fixes.

Patch [1/3] now also addresses varying numbers of DMAC modules and
channels.

Patch [2/3] removes SH_DMAC_BASE1 for SH4 family. To my knowledge, none
of these SoCs feature two DMAC modules.

Patch [3/3] now also sorts all the targets and the description stays
within 80 characters per line.

Tested on Jornada 680 (SH7709 compatible).

I went ahead and verified the above changes against datasheets of all
the SoCs that are currently supported. Only SoCs found in defconfigs
which enable CONFIG_SH_DMA/CONFIG_SH_DMA_API have been surveyed.

---------+--------+--------+--------------+------------------+----------
 SoC     | Family | Refs.  | DMAC modules | Chans per module | Notes  
---------+--------+--------+--------------+------------------+----------
 SH7724  | SH4A   | [1]    | 2            | 6                |
 SH7780  | SH4A   | [2]    | 2            | 6                |
 SH7786  | SH4A   | [3]    | 1 (+ 1)      | 6 (+ 4)          | #1
 SH7091  | SH4    | [4][5] | 1            | 4                | #2
 SH7751R | SH4    | [6]    | 1            | 8                |
 SH7760  | SH4    | [7]    | 1            | 8                |
 SH4-202 | SH4    | n/a    | ?            | ?                | #3
 SH7709  | SH3    | [8]    | 1            | 4                |
 SH7720  | SH3    | [9]    | 1            | 6                |
---------+--------+--------+--------------+------------------+----------

Note #1:
Technically, SH7786 features 2 DMAC modules, for a total of 10 channels.
However, only DMAC0 (6 channels) is hw register compatible with the
existing dma-sh driver.

Note #2:
This SoC, used in SEGA Dreamcast, has no publicly available datasheet.
Apparently it's an SH7750 [5] derivative. Number of modules/channels
has been cross-referenced with the KallistiOS project's source code [4].

Note #3:
No publicly available datasheet for this SoC. Apparently this CPU is
used in an FPGA-based board [10], so perhaps the DMAC properties are
synthesized in FPGA bitstream? As this is SH4, it could potentially
impact patch [2/3].

[1] https://www.renesas.com/us/en/document/mat/sh7724-users-manual-hardware p. 537
[2] https://www.renesas.com/us/en/document/mah/sh7780-hardware-manual p. 609
[3] https://www.renesas.com/us/en/document/mah/sh7786-group-users-manual-hardware p. 1081
[4] https://github.com/KallistiOS/KallistiOS/blob/ebf8d528cd8d1909150f60bef98e1a68318cbb95/kernel/arch/dreamcast/include/dc/asic.h#L91-L94
[5] https://www.renesas.com/us/en/document/mah/sh7750-sh7750s-sh7750r-group-users-manual-hardware p. 597
[6] https://www.renesas.com/us/en/document/mah/sh7751-group-sh7751r-group-users-manual-hardware p. 551
[7] https://www.renesas.com/us/en/document/mah/sh7760-group-hardware-manual p. 463
[8] https://www.renesas.com/us/en/document/mah/sh7709s-group-hardware-manual p. 373
[9] https://www.renesas.com/us/en/document/mah/sh7720-group-sh7721-group-users-manual-hardware p. 467
[10] https://web.archive.org/web/20050405021907/http://www.superh.com/products/microdev.htm

Cheers,
Artur

Artur Rojek (3):
  sh: dma: Fix dma channel offset calculation
  sh: dma: Drop incorrect SH_DMAC_BASE1 for SH4
  sh: dma: Correct the number of DMA channels in SH7709

 arch/sh/drivers/dma/Kconfig       | 14 +++++++-----
 arch/sh/drivers/dma/dma-sh.c      | 37 ++++++++++++++++++++-----------
 arch/sh/include/cpu-sh4/cpu/dma.h |  1 -
 3 files changed, 32 insertions(+), 20 deletions(-)

-- 
2.40.1