linux-kernel - Re: [RFC PATCH v1 2/2] drivers: soc: Add support for Hisilicon Djtag driver

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Message-ID: <CAP=VYLpfsMqPZL4J0K2+NMkxG+RHKchDBA+ZGhza9ZfWAa4VnQ@mail.gmail.com>
Date:	Fri, 22 Jul 2016 16:37:36 -0400
From:	Paul Gortmaker <paul.gortmaker@...il.com>
To:	Tan Xiaojun <tanxiaojun@...wei.com>
Cc:	robh+dt@...nel.org, pawel.moll@....com, mark.rutland@....com,
	ijc+devicetree@...lion.org.uk, galak@...eaurora.org,
	xuwei5@...ilicon.com, devicetree@...r.kernel.org,
	khilman@...aro.org, k.kozlowski@...sung.com, amitdanielk@...il.com,
	heiko@...ech.de, wxt@...k-chips.com, alex.aring@...il.com,
	qiang.zhao@...escale.com, treding@...dia.com,
	rmk+kernel@....linux.org.uk, gregory.clement@...e-electrons.com,
	f.fainelli@...il.com, geert+renesas@...der.be,
	LKML <linux-kernel@...r.kernel.org>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>
Subject: Re: [RFC PATCH v1 2/2] drivers: soc: Add support for Hisilicon Djtag driver

On Fri, Jul 22, 2016 at 4:48 AM, Tan Xiaojun <tanxiaojun@...wei.com> wrote:
> The Hisilicon Djtag is an independent module which connects with some modules
> in the SoC by Debug Bus. This module can be configured to access the registers
> of connecting modules (like L3 cache) during real time debugging.
>
> This patch add the driver of Hisilicon Djtag.
>
> Signed-off-by: Tan Xiaojun <tanxiaojun@...wei.com>
> ---
>  drivers/soc/Kconfig                 |    1 +
>  drivers/soc/Makefile                |    1 +
>  drivers/soc/hisilicon/Kconfig       |   12 ++
>  drivers/soc/hisilicon/Makefile      |    1 +
>  drivers/soc/hisilicon/djtag.c       |  373 +++++++++++++++++++++++++++++++++++
>  include/linux/soc/hisilicon/djtag.h |   18 ++
>  6 files changed, 406 insertions(+)
>  create mode 100644 drivers/soc/hisilicon/Kconfig
>  create mode 100644 drivers/soc/hisilicon/Makefile
>  create mode 100644 drivers/soc/hisilicon/djtag.c
>  create mode 100644 include/linux/soc/hisilicon/djtag.h
>
> diff --git a/drivers/soc/Kconfig b/drivers/soc/Kconfig
> index cb58ef0..f5982ec 100644
> --- a/drivers/soc/Kconfig
> +++ b/drivers/soc/Kconfig
> @@ -3,6 +3,7 @@ menu "SOC (System On Chip) specific Drivers"
>  source "drivers/soc/bcm/Kconfig"
>  source "drivers/soc/brcmstb/Kconfig"
>  source "drivers/soc/fsl/qe/Kconfig"
> +source "drivers/soc/hisilicon/Kconfig"
>  source "drivers/soc/mediatek/Kconfig"
>  source "drivers/soc/qcom/Kconfig"
>  source "drivers/soc/rockchip/Kconfig"
> diff --git a/drivers/soc/Makefile b/drivers/soc/Makefile
> index 380230f..373449d 100644
> --- a/drivers/soc/Makefile
> +++ b/drivers/soc/Makefile
> @@ -7,6 +7,7 @@ obj-$(CONFIG_SOC_BRCMSTB)       += brcmstb/
>  obj-$(CONFIG_ARCH_DOVE)                += dove/
>  obj-$(CONFIG_MACH_DOVE)                += dove/
>  obj-y                          += fsl/
> +obj-$(CONFIG_ARCH_HISI)                += hisilicon/
>  obj-$(CONFIG_ARCH_MEDIATEK)    += mediatek/
>  obj-$(CONFIG_ARCH_QCOM)                += qcom/
>  obj-$(CONFIG_ARCH_RENESAS)     += renesas/
> diff --git a/drivers/soc/hisilicon/Kconfig b/drivers/soc/hisilicon/Kconfig
> new file mode 100644
> index 0000000..3644aab
> --- /dev/null
> +++ b/drivers/soc/hisilicon/Kconfig
> @@ -0,0 +1,12 @@
> +#
> +# Hisilicon SoC drivers
> +#
> +config HISI_DJTAG
> +       bool "Hisilicon Djtag Support"
> +       depends on ARCH_HISI || COMPILE_TEST
> +       help
> +         Say y here to enable the Hisilicon Djtag support. It is an
> +         independent module which connects with some modules in the
> +         SoC by Debug Bus. This module can be configured to access
> +         the registers of connecting modules during real time
> +         debugging.

Choice of word "module" here is probably confusing since it normally
means a ".ko" when used in Kconfig help.   Maybe instead, use:

...independent component...

...connects with some other components....

This driver can be configured to ....

--hopefully  the above will clarify against such confusion.   Also....

> diff --git a/drivers/soc/hisilicon/Makefile b/drivers/soc/hisilicon/Makefile
> new file mode 100644
> index 0000000..35a7b4b
> --- /dev/null
> +++ b/drivers/soc/hisilicon/Makefile
> @@ -0,0 +1 @@
> +obj-$(CONFIG_HISI_DJTAG)       += djtag.o
> diff --git a/drivers/soc/hisilicon/djtag.c b/drivers/soc/hisilicon/djtag.c
> new file mode 100644
> index 0000000..41e11ed
> --- /dev/null
> +++ b/drivers/soc/hisilicon/djtag.c
> @@ -0,0 +1,373 @@
> +/*
> + * Driver for Hisilicon Djtag r/w via System Controller.
> + *
> + * Copyright (C) 2016 Hisilicon Ltd.
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License version 2 as
> + * published by the Free Software Foundation.
> + */
> +
> +#include <linux/bitops.h>
> +#include <linux/init.h>
> +#include <linux/list.h>
> +#include <linux/mfd/syscon.h>
> +#include <linux/module.h>

...since you add the driver as a bool Kconfig item, you should
avoid using module.h and any MODULE_<xyz> tags.  Use the
builtin registration functions instead.

Alternatively, if there is a genuine use case for this to really be
a dynamically loadable .ko module, then convert it to tristate.

Thanks,
Paul.
--
> +#include <linux/of.h>
> +#include <linux/of_address.h>
> +#include <linux/of_device.h>
> +#include <linux/platform_device.h>
> +#include <linux/regmap.h>
> +#include <linux/slab.h>
> +#include <linux/spinlock.h>
> +
> +#include <asm-generic/delay.h>
> +#include <linux/soc/hisilicon/djtag.h>