linux-kernel - Re: [PATCH v3 4/4] clk: microchip: core: allow driver to be compiled with COMPILE

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Message-ID: <e632211c-7ea5-4b27-8a06-24c160b7e947@tuxon.dev>
Date: Sat, 6 Dec 2025 16:28:31 +0200
From: Claudiu Beznea <claudiu.beznea@...on.dev>
To: Brian Masney <bmasney@...hat.com>,
 Michael Turquette <mturquette@...libre.com>, Stephen Boyd
 <sboyd@...nel.org>, Maxime Ripard <mripard@...nel.org>,
 Conor Dooley <conor@...nel.org>, Dan Carpenter <dan.carpenter@...aro.org>
Cc: linux-clk@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 4/4] clk: microchip: core: allow driver to be compiled
 with COMPILE_TEST

Hi, Brian,

On 12/5/25 21:46, Brian Masney wrote:
> This driver currently only supports builds against a PIC32 target. To
> avoid future breakage in the future, let's update the Kconfig and the
> driver so that it can be built with CONFIG_COMPILE_TEST enabled.
> 
> Note that with the existing asm calls is not how I'd want to do this
> today if this was a new driver, however I don't have access to this
> hardware. To avoid any breakage, let's keep the existing behavior.
> 
> Signed-off-by: Brian Masney <bmasney@...hat.com>
> ---
>  drivers/clk/microchip/Kconfig    |  2 +-
>  drivers/clk/microchip/clk-core.c | 32 +++++++++++++++++++++++---------
>  2 files changed, 24 insertions(+), 10 deletions(-)
> 
> diff --git a/drivers/clk/microchip/Kconfig b/drivers/clk/microchip/Kconfig
> index 1b9e43eb54976b219a0277cc971f353fd6af226a..1e56a057319d97e20440fe4e107d26fa85c95ab1 100644
> --- a/drivers/clk/microchip/Kconfig
> +++ b/drivers/clk/microchip/Kconfig
> @@ -1,7 +1,7 @@
>  # SPDX-License-Identifier: GPL-2.0
>  
>  config COMMON_CLK_PIC32
> -	def_bool COMMON_CLK && MACH_PIC32
> +	def_bool (COMMON_CLK && MACH_PIC32) || COMPILE_TEST
>  
>  config MCHP_CLK_MPFS
>  	bool "Clk driver for PolarFire SoC"
> diff --git a/drivers/clk/microchip/clk-core.c b/drivers/clk/microchip/clk-core.c
> index f467d7bc28c87a50fb18dc527574f973c4b7e615..fad4b45d908310ffb59e4ed57c55ae4266253444 100644
> --- a/drivers/clk/microchip/clk-core.c
> +++ b/drivers/clk/microchip/clk-core.c
> @@ -9,7 +9,15 @@
>  #include <linux/interrupt.h>
>  #include <linux/io.h>
>  #include <linux/iopoll.h>
> +
> +#if !defined(CONFIG_MACH_PIC32) && defined(CONFIG_COMPILE_TEST)

Can't we have something like:

#if defined(CONFIG_MATCH_PIC32)
#include <asm/match-pic32/pic32.h>
#else
#define PIC32_CLR(_reg)		((_reg) + 0x04)
#define PIC32_SET(_reg)		((_reg) + 0x08)
#define PIC32_INV(_reg)		((_reg) + 0x0C)
#define pic32_syskey_unlock()
#endif

> +#define PIC32_CLR(_reg)		((_reg) + 0x04)
> +#define PIC32_SET(_reg)		((_reg) + 0x08)
> +#define PIC32_INV(_reg)		((_reg) + 0x0C)
> +#define pic32_syskey_unlock()

On the other side, there are other drivers using these defines, maybe a
unified approach would fit better? Maybe moving these to
include/linux/platform_data ?

> +#else
>  #include <asm/mach-pic32/pic32.h>
> +#endif
>  
>  #include "clk-core.h"
>  
> @@ -74,15 +82,21 @@
>  /* SoC specific clock needed during SPLL clock rate switch */
>  static struct clk_hw *pic32_sclk_hw;
>  
> -/* add instruction pipeline delay while CPU clock is in-transition. */
> -#define cpu_nop5()			\
> -do {					\
> -	__asm__ __volatile__("nop");	\
> -	__asm__ __volatile__("nop");	\
> -	__asm__ __volatile__("nop");	\
> -	__asm__ __volatile__("nop");	\
> -	__asm__ __volatile__("nop");	\
> -} while (0)
> +#if !defined(CONFIG_MACH_PIC32) && defined(CONFIG_COMPILE_TEST)

Same here, can't we have:

#ifdef CONFIG_MATCH_PIC32
#define cpu_nop5()			\
	do {					\
		__asm__ __volatile__("nop");	\
		__asm__ __volatile__("nop");	\
		__asm__ __volatile__("nop");	\
		__asm__ __volatile__("nop");	\
		__asm__ __volatile__("nop");	\
	} while (0)
#else
#define cpu_nop5()
#endif

?

> +#define cpu_nop5()
> +#else
> +{

This leads to the following error when compiling:

../drivers/clk/microchip/clk-core.c:88:1: error: expected identifier or ‘(’
before ‘{’ token
   88 | {
      | ^

Thank you,
Claudiu

> +	/* add instruction pipeline delay while CPU clock is in-transition. */
> +	#define cpu_nop5()			\
> +	do {					\
> +		__asm__ __volatile__("nop");	\
> +		__asm__ __volatile__("nop");	\
> +		__asm__ __volatile__("nop");	\
> +		__asm__ __volatile__("nop");	\
> +		__asm__ __volatile__("nop");	\
> +	} while (0)
> +}
> +#endif
>  
>  /* Perpheral bus clocks */
>  struct pic32_periph_clk {
>