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Date: Tue, 05 Apr 2011 10:04:32 +0200
From: Michal Simek <monstr@...str.eu>
To: John Linn <john.linn@...inx.com>
CC: linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
linux@....linux.org.uk, catalin.marinas@....com,
glikely@...retlab.ca, jamie@...ieiles.com, arnd@...db.de,
Thomas Gleixner <tglx@...utronix.de>
Subject: Re: [PATCH 1/3] ARM: Xilinx: add timer and on chip memory support
for SMP
Hi John,
John Linn wrote:
> These changes are required to support SMP.
>
> This includes an update so that the non-local timer is set
> to run on the 1st CPU, the addition of local timer support
> and support for on chip memory.
>
> Signed-off-by: John Linn <john.linn@...inx.com>
> ---
> arch/arm/mach-xilinx/common.c | 16 ++++++++++-
> arch/arm/mach-xilinx/include/mach/irqs.h | 1 +
> arch/arm/mach-xilinx/include/mach/xilinx_soc.h | 20 +++++++++++++
> arch/arm/mach-xilinx/localtimer.c | 36 ++++++++++++++++++++++++
> arch/arm/mach-xilinx/timer.c | 4 +-
> 5 files changed, 74 insertions(+), 3 deletions(-)
> create mode 100644 arch/arm/mach-xilinx/localtimer.c
>
> diff --git a/arch/arm/mach-xilinx/common.c b/arch/arm/mach-xilinx/common.c
> index 83b549d..2695b39 100644
> --- a/arch/arm/mach-xilinx/common.c
> +++ b/arch/arm/mach-xilinx/common.c
> @@ -101,7 +101,21 @@ static struct map_desc io_desc[] __initdata = {
> .type = MT_DEVICE,
> },
> #endif
> -
> + /* create a mapping for the OCM (256K) leaving a hole for the
> + * interrupt vectors which are handled in the kernel
> + */
> + {
> + .virtual = OCM_LOW_VIRT,
> + .pfn = __phys_to_pfn(OCM_LOW_PHYS),
> + .length = (192 * SZ_1K),
> + .type = MT_DEVICE_CACHED,
> + },
> + {
> + .virtual = OCM_HIGH_VIRT,
> + .pfn = __phys_to_pfn(OCM_HIGH_PHYS),
> + .length = (60 * SZ_1K),
> + .type = MT_DEVICE,
> + },
> };
>
> /**
> diff --git a/arch/arm/mach-xilinx/include/mach/irqs.h b/arch/arm/mach-xilinx/include/mach/irqs.h
> index 47a8162..8c41b22 100644
> --- a/arch/arm/mach-xilinx/include/mach/irqs.h
> +++ b/arch/arm/mach-xilinx/include/mach/irqs.h
> @@ -22,6 +22,7 @@
> * GIC Interrupts
> */
>
> +#define IRQ_SCU_CPU_TIMER 29
> #define IRQ_GIC_SPI_START 32
> #define IRQ_TIMERCOUNTER0 42
> #define IRQ_UART0 59
> diff --git a/arch/arm/mach-xilinx/include/mach/xilinx_soc.h b/arch/arm/mach-xilinx/include/mach/xilinx_soc.h
> index d181c5c..a55a46c 100644
> --- a/arch/arm/mach-xilinx/include/mach/xilinx_soc.h
> +++ b/arch/arm/mach-xilinx/include/mach/xilinx_soc.h
> @@ -31,13 +31,33 @@
> #define SCU_PERIPH_PHYS 0xF8F00000
> #define SCU_PERIPH_VIRT SCU_PERIPH_PHYS
>
> +#define OCM_LOW_PHYS 0xFFFC0000
> +#define OCM_LOW_VIRT OCM_LOW_PHYS
> +
> +#define OCM_HIGH_PHYS 0xFFFF1000
> +#define OCM_HIGH_VIRT OCM_HIGH_PHYS
> +
> /* The following are intended for the devices that are mapped early */
>
> #define TTC0_BASE IOMEM(TTC0_VIRT)
> #define SCU_PERIPH_BASE IOMEM(SCU_PERIPH_VIRT)
> #define SCU_GIC_CPU_BASE (SCU_PERIPH_BASE + 0x100)
> +#define SCU_CPU_TIMER_BASE (SCU_PERIPH_BASE + 0x600)
> #define SCU_GIC_DIST_BASE (SCU_PERIPH_BASE + 0x1000)
> #define PL310_L2CC_BASE IOMEM(PL310_L2CC_VIRT)
> +#define OCM_LOW_BASE IOMEM(OCM_LOW_VIRT)
> +#define OCM_HIGH_BASE IOMEM(OCM_HIGH_VIRT)
> +
> +/* There are a couple ram addresses needed for communication between the boot
> + * loader software and the linux kernel with multiple cpus in the kernel (SMP).
> + * The memory addresses are in the high on-chip RAM and these addresses are
> + * mapped flat (virtual = physical). The memory must be mapped early and
> + * non-cached.
> + */
> +
> +#define BOOT_ADDR_OFFSET 0xEFF0
> +#define BOOT_LOCK_OFFSET 0xEFF4
> +#define BOOT_LOCK_KEY 0xFACECAFE
>
> /*
> * Mandatory for CONFIG_LL_DEBUG, UART is mapped virtual = physical
> diff --git a/arch/arm/mach-xilinx/localtimer.c b/arch/arm/mach-xilinx/localtimer.c
> new file mode 100644
> index 0000000..4bd0a0d
> --- /dev/null
> +++ b/arch/arm/mach-xilinx/localtimer.c
> @@ -0,0 +1,36 @@
> +/*
> + * arch/arm/mach-xilinx/localtimer.c
> + *
> + * Both cortex-a9 cores have their own timer in it's CPU domain.
> + *
> + * Copyright (C) 2011 Xilinx, Inc.
> + *
> + * This file is based on arch/arm/plat-versatile/localtimer.c
> + *
> + * Copyright (C) 2002 ARM Ltd.
> + *
> + * This software is licensed under the terms of the GNU General Public
> + * License version 2, as published by the Free Software Foundation, and
> + * may be copied, distributed, and modified under those terms.
> + *
> + * This program is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
> + * GNU General Public License for more details.
> + */
> +#include <linux/init.h>
> +#include <asm/smp_twd.h>
> +#include <mach/xilinx_soc.h>
> +
> +/*
> + * Setup the local clock events for a CPU.
> + */
> +int __cpuinit local_timer_setup(struct clock_event_device *evt)
> +{
> + twd_base = SCU_CPU_TIMER_BASE;
> +
> + evt->irq = IRQ_SCU_CPU_TIMER;
> + twd_timer_setup(evt);
> + return 0;
> +}
I have question here about SCU_CPU_TIMER_BASE.
I have looked at your arm-next branch and you are using there TTC0_BASE
at 0xF8001000 address which is external timer.
Here you are using SCU internal timer at 0xF8F00600.
You are using TTC with three counters (from your comment).
T1: Timer 1, clocksource for generic timekeeping
T2: Timer 2, clockevent source for hrtimers
T3: Timer 3, <unused>
From twd_timer_setup I see that it looks like that only new clockevent is
registered.
Please correct me if I am wrong.
Would it be possible to use timer 3 for the second cpu? I expect that your code
just register new clockevent device. System will contain 2 CPU that's why this
shouldn't be a problem.
TGLX: Is it correct assumption that SMP system has one clocksource and one
clockevent device for every CPU in the system? (Sorry I don't have any
experience with SMP)
I don't know if there is an option to use only internal CPU timers for Linux and
keep ttc for other purpose.
BTW: I think that will be better to spit this patch to two. The first for local
timer and the second for OCM.
Thanks,
Michal
--
Michal Simek, Ing. (M.Eng)
w: www.monstr.eu p: +42-0-721842854
Maintainer of Linux kernel 2.6 Microblaze Linux - http://www.monstr.eu/fdt/
Microblaze U-BOOT custodian
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