Subject: [PATCH v3] ARM: Make a compile firmware conditionally

From: [email-masked] (Dave Martin)
Date: Fri, 20 Jul 2012 10:42:56 +0100

On Fri, Jul 20, 2012 at 05:24:19PM +0900, Kyungmin Park wrote:
> From: Kyungmin Park <[email-masked]>
> 
> Some boards can use the firmware at trustzone but others can't use this.

Note that this isn't just about TrustZone.  For example, firmware could
be implemented in a hypervisor.

> However we need to build it simultaneously. To address this issue,
> introduce arm firmware support and use it at each board files.
> 
> e.g., In boot_secondary at mach-exynos/platsmp.c
> 
>         __raw_writel(virt_to_phys(exynos4_secondary_startup),
>                 CPU1_BOOT_REG);
> 
>         if (IS_ENABLED(CONFIG_ARM_FIRMWARE)) {
>                 /* Call Exynos specific smc call */
>                 firmware_ops.cpu_boot(cpu);
>         }
> 
>         gic_raise_softirq(cpumask_of(cpu), 1);
> 
>         if (pen_release == -1)
> 
> Now smp_ops is not yet merged, now just call the firmware_init at init_early
>  at board file
> 
> e.g., exynos4412 based board
> 
> static void __init board_init_early(void)
> {
>         exynos_firmware_init();
> }
> 
> TODO
>         1. DT support.
>         2. call firmware init by smp_ops.
> 
> Signed-off-by: Kyungmin Park <[email-masked]>
> ---
> diff --git a/arch/arm/common/Kconfig b/arch/arm/common/Kconfig
> index 283fa1d..5b097ca 100644
> --- a/arch/arm/common/Kconfig
> +++ b/arch/arm/common/Kconfig
> @@ -21,6 +21,9 @@ config ARM_VIC_NR
>  	  The maximum number of VICs available in the system, for
>  	  power management.
>  
> +config ARM_FIRMWARE
> +	bool
> +
>  config ICST
>  	bool
>  
> diff --git a/arch/arm/common/Makefile b/arch/arm/common/Makefile
> index e8a4e58..4af6568 100644
> --- a/arch/arm/common/Makefile
> +++ b/arch/arm/common/Makefile
> @@ -4,6 +4,7 @@
>  
>  obj-$(CONFIG_ARM_GIC)		+= gic.o
>  obj-$(CONFIG_ARM_VIC)		+= vic.o
> +obj-$(CONFIG_ARM_FIRMWARE)	+= firmware.o
>  obj-$(CONFIG_ICST)		+= icst.o
>  obj-$(CONFIG_SA1111)		+= sa1111.o
>  obj-$(CONFIG_PCI_HOST_VIA82C505) += via82c505.o
> diff --git a/arch/arm/common/firmware.c b/arch/arm/common/firmware.c
> new file mode 100644
> index 0000000..ffb6822
> --- /dev/null
> +++ b/arch/arm/common/firmware.c
> @@ -0,0 +1,23 @@
> +/*
> + *  Copyright (C) 2012 Samsung Electronics.
> + *  Kyungmin Park <[email-masked]>
> + *
> + * 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/kernel.h>
> +#include <linux/suspend.h>
> +
> +#include <asm/firmware.h>
> +
> +static void cpu_boot(int cpu)
> +{
> +	/* Do nothing */
> +}
> +
> +struct firmware_ops firmware_ops = {
> +	.do_idle		= cpu_do_idle,
> +	.cpu_boot		= cpu_boot,
> +};
> diff --git a/arch/arm/include/asm/firmware.h b/arch/arm/include/asm/firmware.h
> new file mode 100644
> index 0000000..c8c28bf
> --- /dev/null
> +++ b/arch/arm/include/asm/firmware.h
> @@ -0,0 +1,20 @@
> +/*
> + *  Copyright (C) 2012 Samsung Electronics.
> + *  Kyungmin Park <[email-masked]>
> + *
> + * 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.
> + */
> +
> +#ifndef __ASM_ARM_FIRMWARE_H
> +#define __ASM_ARM_FIRMWARE_H
> +
> +struct firmware_ops {
> +	int	(*do_idle)(void);
> +	void	(*cpu_boot)(int cpu);
> +};
> +
> +extern struct firmware_ops firmware_ops;
> +
> +#endif

Do you plan to have a registration interface for this?

I imagine that struct firmware_ops will get extended over time, so
it might contain many different function pointers.  Each board will
probably only provide a subset of these, by sparsely populating its
own struct firmware_ops (similarly to other existing registration
interfaces).

It may make sense to have a way to define default fallback actions for
ops not defined by a particular board.  If CONFIG_ARM_FIRMWARE=n, we
could use the fallbacks for everything.

Cheers
---Dave