[PATCH 2/2] RTEMS changes for lpc32xx VFP support

[Kirspel, Kevin]

The Coprocessor access control register is not VFP dependent.  Processors either have one or not (V5TEJ does not).  The VFP run fast option in the FPSCR may be unique to each VFP version (I'm not sure).  For now, we could introduce defines such as the following to distinguish between the different VFP versions and features.

ARM_MULTILIB_VFPV2_D16
ARM_MULTILIB_VFPV3_D16
ARM_MULTILIB_VFPV3_D32
ARM_MULTILIB_VFPV4_D16
ARM_MULTILIB_VFPV4_D32
ARM_MULTILIB_VFPV5_D16
ARM_MULTILIB_NEON

#if defined(ARM_MULTILIB_VFPV2_D16) \
  || defined(ARM_MULTILIB_VFPV3_D16) \
  || defined(ARM_MULTILIB_VFPV3_D32) \
  || defined(ARM_MULTILIB_VFPV4_D16) \
  || defined(ARM_MULTILIB_VFPV4_D32) \
  || defined(ARM_MULTILIB_VFPV5_D16) \
  || defined(ARM_MULTILIB_ NEON)
  #define ARM_MULTILIB_VFP
#endif

#if defined(ARM_MULTILIB_VFPV2_D16)
  #define ARM_MULTILIB_VFP_RUN_FAST
#endif

Kevin Kirspel
Electrical Engineer - Sr. Staff
Opti Medical
235 Hembree Park Drive
Roswell GA 30076
Tel: (770)-510-4444 ext. 81642
Direct: (770)-688-1642
Fax: (770)-510-4445

-----Original Message-----
From: Sebastian Huber [mailto:sebastian.huber at embedded-brains.de] 
Sent: Friday, August 19, 2016 1:42 AM
To: Kirspel, Kevin <Kevin-Kirspel at idexx.com>; devel at rtems.org
Subject: Re: [PATCH 2/2] RTEMS changes for lpc32xx VFP support



On 19/08/16 02:16, Kirspel, Kevin wrote:
>
> diff --git a/c/src/lib/libbsp/arm/lpc32xx/make/custom/lpc32xx.inc
> b/c/src/lib/libbsp/arm/lpc32xx/make/custom/lpc32xx.inc
>
> old mode 100644
>
> new mode 100755
>
> index f184741..1d478ce
>
> --- a/c/src/lib/libbsp/arm/lpc32xx/make/custom/lpc32xx.inc
>
> +++ b/c/src/lib/libbsp/arm/lpc32xx/make/custom/lpc32xx.inc
>
> @@ -6,7 +6,8 @@ include $(RTEMS_ROOT)/make/custom/default.cfg
>
>  RTEMS_CPU = arm
>
> -CPU_CFLAGS = -mcpu=arm926ej-s -mthumb
>
> +#CPU_CFLAGS = -mcpu=arm926ej-s -mthumb
>
> +CPU_CFLAGS = -mcpu=arm926ej-s -mfpu=vfp -mfloat-abi=softfp
>
>  CFLAGS_OPTIMIZE_V ?= -O2 -g
>
> CFLAGS_OPTIMIZE_V += -ffunction-sections -fdata-sections
>
> diff --git a/c/src/lib/libbsp/arm/shared/start/start.S
> b/c/src/lib/libbsp/arm/shared/start/start.S
>
> old mode 100644
>
> new mode 100755
>
> index 30501be..cb3bff7
>
> --- a/c/src/lib/libbsp/arm/shared/start/start.S
>
> +++ b/c/src/lib/libbsp/arm/shared/start/start.S
>
> @@ -19,9 +19,9 @@
>
>   */
>
>  #include <rtems/asm.h>
>
> -#include <rtems/system.h>
>
> +#include <rtems/system.h>
>
> #include <rtems/score/cpu.h>
>
> -
>
> +
>
> #include <bspopts.h>
>
> #include <bsp/irq.h>
>
> #include <bsp/linker-symbols.h>
>
> @@ -265,6 +265,7 @@ bsp_start_skip_hyp_svc_switch:
>
>                /* Stay in SVC mode */
>
>  #ifdef ARM_MULTILIB_VFP
>
> +#ifndef ARM_MULTILIB_ARCH_V5TEJ
>

I think a multilib define reflecting the VFP feature set would be better instead of this ARM_MULTILIB_ARCH_V5TEJ.

>                /* Read CPACR */
>
>                mrc p15, 0, r0, c1, c0, 2
>
> @@ -280,11 +281,18 @@ bsp_start_skip_hyp_svc_switch:
>
>                /* Write CPACR */
>
>                mcr p15, 0, r0, c1, c0, 2
>
>                isb
>
> +#endif
>
>                 /* Enable FPU */
>
>                mov r0, #(1 << 30)
>
>                vmsr FPEXC, r0
>
> +#ifdef ARM_MULTILIB_ARCH_V5TEJ
>
> +             /* Enable FPU Run Fast*/
>
> +             mov r0, #(3 << 24)
>
> +             vmsr FPSCR, r0
>
> +#endif
>
> +
>
> #ifdef BSP_START_NEEDS_REGISTER_INITIALIZATION
>
>                bl bsp_start_init_registers_vfp
>
> #endif
>
> @@ -399,6 +407,7 @@ _start:
>
> #endif
>
>  #ifdef ARM_MULTILIB_VFP
>
> +#ifndef ARM_MULTILIB_ARCH_V5TEJ
>
>                /*
>
>                 * Enable CP10 and CP11 coprocessors for privileged and 
> user mode in
>
>                 * CPACR (bits 20-23). Ensure that write to register 
> completes.
>
> @@ -409,6 +418,7 @@ _start:
>
>                str           r1, [r0]
>
>                dsb
>
>                isb
>
> +#endif
>
>  #ifdef BSP_START_NEEDS_REGISTER_INITIALIZATION
>
>                bl bsp_start_init_registers_vfp
>
> diff --git a/cpukit/score/cpu/arm/arm-context-validate.S
> b/cpukit/score/cpu/arm/arm-context-validate.S
>
> old mode 100644
>
> new mode 100755
>
> index fdfb6c1..6485993
>
> --- a/cpukit/score/cpu/arm/arm-context-validate.S
>
> +++ b/cpukit/score/cpu/arm/arm-context-validate.S
>
> @@ -46,7 +46,11 @@
>
>                 .section .text
>
> +#ifdef __thumb__
>
> FUNCTION_THUMB_ENTRY(_CPU_Context_validate)
>
> +#else
>
> +FUNCTION_ENTRY(_CPU_Context_validate)
>
> +#endif
>

I checked in a slightly modified version for the VFP context validation.

--
Sebastian Huber, embedded brains GmbH

Address : Dornierstr. 4, D-82178 Puchheim, Germany
Phone   : +49 89 189 47 41-16
Fax     : +49 89 189 47 41-09
E-Mail  : sebastian.huber at embedded-brains.de
PGP     : Public key available on request.

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