Re: [PATCH 3/3] ARM: BCM: Add SMP support for Broadcom NSP

[Kapil Hali <kapilh@broadcom.com>]

On 10/16/2015 2:47 AM, Jon Mason wrote:
> On Thu, Oct 15, 2015 at 11:12:09PM +0200, Hauke Mehrtens wrote:
>> On 10/15/2015 06:10 PM, Kapil Hali wrote:
>>>
>>>
>>> On 10/15/2015 3:56 AM, Hauke Mehrtens wrote:
>>>> On 10/14/2015 07:47 PM, Kapil Hali wrote:
>>>>> Add SMP support for Broadcom's Northstar Plus SoC,
>>>>> cpu enable method and pen_release procedures. This
>>>>> changes also consolidates iProc family's - BCM NSP
>>>>> and BCM Kona, SMP handling in a common file.
>>>>
>>>> This will probably also work on normal Northstar CPUs without changes.
>>>>
>>> I think, it should work for most of the variants of Northstar family, 
>>> except for those which have a BOOTROM bug.
>>
>> Which SoC are affected by this BOOTROM bug?
> 
> 53012 is the one I am seeing.  Not seeing it on 4708 (and assuming it is
> not present on 4709).  Internally, we do the ugly bug workaround on
> all Northstar SoCs.  The workaround is not acceptable upstream, so I
> am not pushing it. :)
> 
> Thanks,
> Jon
> 

Hi Hauke,

Now that you have tested Jon's patch which is based on my changes for
SMP, shall I take his changes and add it on top of my changes and resend?
Also, do I consider your Acked-by and Tested-by for the change?

Thanks,
Kapil

>>
>>>>> Northstar Plus SoC is based on ARM Cortex-A9
>>>>> revision r3p0 which requires configuration for ARM
>>>>> Errata 764369 for SMP. This change adds the needed
>>>>> configuration option.
>>>>>
>>>>> Signed-off-by: Kapil Hali <kapilh@broadcom.com>
>>>>> ---
>>>>>  arch/arm/mach-bcm/Kconfig                   |   2 +
>>>>>  arch/arm/mach-bcm/Makefile                  |   8 +-
>>>>>  arch/arm/mach-bcm/bcm_nsp.h                 |  19 ++++
>>>>>  arch/arm/mach-bcm/headsmp.S                 |  37 ++++++++
>>>>>  arch/arm/mach-bcm/{kona_smp.c => platsmp.c} | 142 ++++++++++++++++++++++++++--
>>>>>  5 files changed, 197 insertions(+), 11 deletions(-)
>>>>>  create mode 100644 arch/arm/mach-bcm/bcm_nsp.h
>>>>>  create mode 100644 arch/arm/mach-bcm/headsmp.S
>>>>>  rename arch/arm/mach-bcm/{kona_smp.c => platsmp.c} (63%)
>>>>>
>>>>> diff --git a/arch/arm/mach-bcm/Kconfig b/arch/arm/mach-bcm/Kconfig
>>>>> index 1679fa4..2e9dbb5 100644
>>>>> --- a/arch/arm/mach-bcm/Kconfig
>>>>> +++ b/arch/arm/mach-bcm/Kconfig
>>>>> @@ -40,6 +40,8 @@ config ARCH_BCM_NSP
>>>>>  	select ARCH_BCM_IPROC
>>>>>  	select ARM_ERRATA_754322
>>>>>  	select ARM_ERRATA_775420
>>>>> +	select ARM_ERRATA_764369 if SMP
>>>>> +	select HAVE_SMP
>>>>>  	help
>>>>>  	  Support for Broadcom Northstar Plus SoC.
>>>>>  	  Broadcom Northstar Plus family of SoCs are used for switching control
>>>>> diff --git a/arch/arm/mach-bcm/Makefile b/arch/arm/mach-bcm/Makefile
>>>>> index 892261f..36a4ca30 100644
>>>>> --- a/arch/arm/mach-bcm/Makefile
>>>>> +++ b/arch/arm/mach-bcm/Makefile
>>>>> @@ -14,7 +14,11 @@
>>>>>  obj-$(CONFIG_ARCH_BCM_CYGNUS) +=  bcm_cygnus.o
>>>>>  
>>>>>  # Northstar Plus
>>>>> -obj-$(CONFIG_ARCH_BCM_NSP) += bcm_nsp.o
>>>>> +obj-$(CONFIG_ARCH_BCM_NSP)	+= bcm_nsp.o
>>>>> +
>>>>> +ifeq ($(CONFIG_ARCH_BCM_NSP),y)
>>>>> +obj-$(CONFIG_SMP)		+= headsmp.o platsmp.o
>>>>> +endif
>>>>>  
>>>>>  # BCM281XX
>>>>>  obj-$(CONFIG_ARCH_BCM_281XX)	+= board_bcm281xx.o
>>>>> @@ -23,7 +27,7 @@ obj-$(CONFIG_ARCH_BCM_281XX)	+= board_bcm281xx.o
>>>>>  obj-$(CONFIG_ARCH_BCM_21664)	+= board_bcm21664.o
>>>>>  
>>>>>  # BCM281XX and BCM21664 SMP support
>>>>> -obj-$(CONFIG_ARCH_BCM_MOBILE_SMP) += kona_smp.o
>>>>> +obj-$(CONFIG_ARCH_BCM_MOBILE_SMP) += platsmp.o
>>>>>  
>>>>>  # BCM281XX and BCM21664 L2 cache control
>>>>>  obj-$(CONFIG_ARCH_BCM_MOBILE_L2_CACHE) += kona_l2_cache.o
>>>>> diff --git a/arch/arm/mach-bcm/bcm_nsp.h b/arch/arm/mach-bcm/bcm_nsp.h
>>>>> new file mode 100644
>>>>> index 0000000..58e1e80
>>>>> --- /dev/null
>>>>> +++ b/arch/arm/mach-bcm/bcm_nsp.h
>>>>> @@ -0,0 +1,19 @@
>>>>> +/*
>>>>> + * Copyright (C) 2015 Broadcom Corporation
>>>>> + *
>>>>> + * This program is free software; you can redistribute it and/or
>>>>> + * modify it under the terms of the GNU General Public License as
>>>>> + * published by the Free Software Foundation version 2.
>>>>> + *
>>>>> + * This program is distributed "as is" WITHOUT ANY WARRANTY of any
>>>>> + * kind, whether express or implied; without even the implied warranty
>>>>> + * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
>>>>> + * GNU General Public License for more details.
>>>>> + */
>>>>> +
>>>>> +#ifndef __BCM_NSP_H
>>>>> +#define __BCM_NSP_H
>>>>> +
>>>>> +extern void nsp_secondary_startup(void);
>>>>> +
>>>>> +#endif /* __BCM_NSP_H */
>>>>> diff --git a/arch/arm/mach-bcm/headsmp.S b/arch/arm/mach-bcm/headsmp.S
>>>>> new file mode 100644
>>>>> index 0000000..0da13b2
>>>>> --- /dev/null
>>>>> +++ b/arch/arm/mach-bcm/headsmp.S
>>>>> @@ -0,0 +1,37 @@
>>>>> +/*
>>>>> + * Copyright (C) 2015 Broadcom Corporation
>>>>> + *
>>>>> + * This program is free software; you can redistribute it and/or
>>>>> + * modify it under the terms of the GNU General Public License as
>>>>> + * published by the Free Software Foundation version 2.
>>>>> + *
>>>>> + * This program is distributed "as is" WITHOUT ANY WARRANTY of any
>>>>> + * kind, whether express or implied; without even the implied warranty
>>>>> + * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
>>>>> + * GNU General Public License for more details.
>>>>> + */
>>>>> +
>>>>> +#include <linux/linkage.h>
>>>>> +
>>>>> +/*
>>>>> + * iProc specific entry point for secondary CPUs.  This provides
>>>>> + * a "holding pen" into which all secondary cores are held until
>>>>> + * we are ready for them to initialise.
>>>>> + */
>>>>> +ENTRY(nsp_secondary_startup)
>>>>> +	mrc     p15, 0, r0, c0, c0, 5
>>>>> +	and     r0, r0, #15
>>>>> +	adr     r4, 1f
>>>>> +	ldmia   r4, {r5, r6}
>>>>> +	sub     r4, r4, r5
>>>>> +	add     r6, r6, r4
>>>>> +pen:	ldr     r7, [r6]
>>>>> +	cmp     r7, r0
>>>>> +	bne     pen
>>>>> +
>>>>> +	b    secondary_startup
>>>>> +
>>>>> +1:	.long   .
>>>>> +	.long   pen_release
>>>>> +
>>>>> +ENDPROC(nsp_secondary_startup)
>>>>> diff --git a/arch/arm/mach-bcm/kona_smp.c b/arch/arm/mach-bcm/platsmp.c
>>>>> similarity index 63%
>>>>> rename from arch/arm/mach-bcm/kona_smp.c
>>>>> rename to arch/arm/mach-bcm/platsmp.c
>>>>> index 66a0465..619030e 100644
>>>>> --- a/arch/arm/mach-bcm/kona_smp.c
>>>>> +++ b/arch/arm/mach-bcm/platsmp.c
>>>>> @@ -1,5 +1,5 @@
>>>>>  /*
>>>>> - * Copyright (C) 2014 Broadcom Corporation
>>>>> + * Copyright (C) 2014-2015 Broadcom Corporation
>>>>>   * Copyright 2014 Linaro Limited
>>>>>   *
>>>>>   * This program is free software; you can redistribute it and/or
>>>>> @@ -12,16 +12,23 @@
>>>>>   * GNU General Public License for more details.
>>>>>   */
>>>>>  
>>>>> -#include <linux/init.h>
>>>>> +#include <linux/cpumask.h>
>>>>> +#include <linux/delay.h>
>>>>>  #include <linux/errno.h>
>>>>> +#include <linux/init.h>
>>>>>  #include <linux/io.h>
>>>>> +#include <linux/jiffies.h>
>>>>>  #include <linux/of.h>
>>>>>  #include <linux/sched.h>
>>>>> +#include <linux/smp.h>
>>>>>  
>>>>> +#include <asm/cacheflush.h>
>>>>>  #include <asm/smp.h>
>>>>>  #include <asm/smp_plat.h>
>>>>>  #include <asm/smp_scu.h>
>>>>>  
>>>>> +#include "bcm_nsp.h"
>>>>> +
>>>>>  /* Size of mapped Cortex A9 SCU address space */
>>>>>  #define CORTEX_A9_SCU_SIZE	0x58
>>>>>  
>>>>> @@ -34,6 +41,24 @@
>>>>>  /* I/O address of register used to coordinate secondary core startup */
>>>>>  static u32	secondary_boot;
>>>>>  
>>>>> +static DEFINE_SPINLOCK(boot_lock);
>>>>> +
>>>>> +/*
>>>>> + * Write pen_release in a way that is guaranteed to be visible to all
>>>>> + * observers, irrespective of whether they're taking part in coherency
>>>>> + * or not.  This is necessary for the hotplug code to work reliably.
>>>>> + */
>>>>> +static void write_pen_release(int val)
>>>>> +{
>>>>> +	pen_release = val;
>>>>> +	/*
>>>>> +	 * Ensure write to pen_release is visible to the other cores,
>>>>> +	 * here - primary core
>>>>> +	 */
>>>>> +	smp_wmb();
>>>>> +	sync_cache_w(&pen_release);
>>>>> +}
>>>>> +
>>>>>  /*
>>>>>   * Enable the Cortex A9 Snoop Control Unit
>>>>>   *
>>>>> @@ -75,6 +100,51 @@ static int __init scu_a9_enable(void)
>>>>>  	return 0;
>>>>>  }
>>>>>  
>>>>> +static int nsp_write_lut(void (*secondary_startup) (void))
>>>>> +{
>>>>> +	void __iomem *sku_rom_lut;
>>>>> +	phys_addr_t secondary_startup_phy;
>>>>> +
>>>>> +	if (!secondary_boot) {
>>>>> +		pr_warn("required secondary boot register not specified\n");
>>>>> +		return -EINVAL;
>>>>> +	}
>>>>> +
>>>>> +	sku_rom_lut = ioremap_nocache((phys_addr_t)secondary_boot,
>>>>> +						sizeof(secondary_boot));
>>>>> +	if (!sku_rom_lut) {
>>>>> +		pr_warn("unable to ioremap SKU-ROM LUT register\n");
>>>>> +		return -ENOMEM;
>>>>> +	}
>>>>> +
>>>>> +	secondary_startup_phy = virt_to_phys(secondary_startup);
>>>>> +	BUG_ON(secondary_startup_phy > (phys_addr_t)U32_MAX);
>>>>> +
>>>>> +	writel_relaxed(secondary_startup_phy, sku_rom_lut);
>>>>> +	/*
>>>>> +	 * Ensure the write is visible to the secondary core.
>>>>> +	 */
>>>>> +	smp_wmb();
>>>>> +
>>>>> +	iounmap(sku_rom_lut);
>>>>> +
>>>>> +	return 0;
>>>>> +}
>>>>> +
>>>>> +static void nsp_secondary_init(unsigned int cpu)
>>>>> +{
>>>>> +	/*
>>>>> +	 * Let the primary cpu know we are out of holding pen.
>>>>> +	 */
>>>>> +	write_pen_release(-1);
>>>>> +
>>>>> +	/*
>>>>> +	 * Synchronise with the boot thread.
>>>>> +	 */
>>>>> +	spin_lock(&boot_lock);
>>>>> +	spin_unlock(&boot_lock);
>>>>> +}
>>>>> +
>>>>>  static void __init bcm_smp_prepare_cpus(unsigned int max_cpus)
>>>>>  {
>>>>>  	static cpumask_t only_cpu_0 = { CPU_BITS_CPU0 };
>>>>> @@ -95,11 +165,11 @@ static void __init bcm_smp_prepare_cpus(unsigned int max_cpus)
>>>>>  	/*
>>>>>  	 * Our secondary enable method requires a "secondary-boot-reg"
>>>>>  	 * property to specify a register address used to request the
>>>>> -	 * ROM code boot a secondary code.  If we have any trouble
>>>>> +	 * ROM code boot a secondary core.  If we have any trouble
>>>>>  	 * getting this we fall back to uniprocessor mode.
>>>>>  	 */
>>>>>  	if (of_property_read_u32(node, OF_SECONDARY_BOOT, &secondary_boot)) {
>>>>> -		pr_err("%s: missing/invalid " OF_SECONDARY_BOOT " property\n",
>>>>> +		pr_warn("%s: missing/invalid " OF_SECONDARY_BOOT " property\n",
>>>>>  			node->name);
>>>>>  		ret = -ENOENT;		/* Arrange to disable SMP */
>>>>>  		goto out;
>>>>> @@ -115,7 +185,6 @@ out:
>>>>>  	of_node_put(node);
>>>>>  	if (ret) {
>>>>>  		/* Update the CPU present map to reflect uniprocessor mode */
>>>>> -		BUG_ON(ret != -ENOENT);
>>>>>  		pr_warn("disabling SMP\n");
>>>>>  		init_cpu_present(&only_cpu_0);
>>>>>  	}
>>>>> @@ -139,7 +208,7 @@ out:
>>>>>   * - Wait for the secondary boot register to be re-written, which
>>>>>   *   indicates the secondary core has started.
>>>>>   */
>>>>> -static int bcm_boot_secondary(unsigned int cpu, struct task_struct *idle)
>>>>> +static int kona_boot_secondary(unsigned int cpu, struct task_struct *idle)
>>>>>  {
>>>>>  	void __iomem *boot_reg;
>>>>>  	phys_addr_t boot_func;
>>>>> @@ -162,7 +231,7 @@ static int bcm_boot_secondary(unsigned int cpu, struct task_struct *idle)
>>>>>  	boot_reg = ioremap_nocache((phys_addr_t)secondary_boot, sizeof(u32));
>>>>>  	if (!boot_reg) {
>>>>>  		pr_err("unable to map boot register for cpu %u\n", cpu_id);
>>>>> -		return -ENOSYS;
>>>>> +		return -ENOMEM;
>>>>>  	}
>>>>>  
>>>>>  	/*
>>>>> @@ -191,12 +260,67 @@ static int bcm_boot_secondary(unsigned int cpu, struct task_struct *idle)
>>>>>  
>>>>>  	pr_err("timeout waiting for cpu %u to start\n", cpu_id);
>>>>>  
>>>>> -	return -ENOSYS;
>>>>> +	return -ENXIO;
>>>>> +}
>>>>> +
>>>>> +static int nsp_boot_secondary(unsigned int cpu, struct task_struct *idle)
>>>>> +{
>>>>> +	unsigned long timeout;
>>>>> +	int ret;
>>>>> +
>>>>> +	/*
>>>>> +	 * After wake up, secondary core branches to the startup
>>>>> +	 * address programmed at SKU ROM LUT location.
>>>>> +	 */
>>>>> +	ret = nsp_write_lut(nsp_secondary_startup);
>>>>> +	if (ret) {
>>>>> +		pr_err("unable to write startup addr to SKU ROM LUT\n");
>>>>> +		goto out;
>>>>> +	}
>>>>> +
>>>>> +	/*
>>>>> +	 * The secondary processor is waiting to be released from
>>>>> +	 * the holding pen - release it, then wait for it to flag
>>>>> +	 * that it has been released by resetting pen_release.
>>>>> +	 */
>>>>> +	spin_lock(&boot_lock);
>>>>> +
>>>>> +	write_pen_release(cpu_logical_map(cpu));
>>>>> +	/*
>>>>> +	 * Send an Event to wake up the secondary core which is in
>>>>> +	 * WFE state. Updated pen_release should also be visible to
>>>>> +	 * the secondary core.
>>>>> +	 */
>>>>> +	dsb_sev();
>>>>> +
>>>>> +	timeout = jiffies + (1 * HZ);
>>>>> +	while (time_before(jiffies, timeout)) {
>>>>> +		/* Make sure loads on other CPU is visible */
>>>>> +		smp_rmb();
>>>>> +		if (pen_release == -1)
>>>>> +			break;
>>>>> +
>>>>> +		udelay(10);
>>>>> +	}
>>>>> +
>>>>> +	spin_unlock(&boot_lock);
>>>>
>>>> Why is this boot_lock needed? As far as I understand it asserts that
>>>> both CPUs leave nsp_boot_secondary() and nsp_secondary_init() at the
>>>> same time.
>>>>
>>> It makes sure secondary cpu doesn't run away before primary cpu 
>>> recognizes the presence of secondary cpu, it is a way of 
>>> synchronization between primary and secondary cpu. This is the
>>> method used across many SoCs.
>>>>> +
>>>>> +	ret = pen_release != -1 ? -ENXIO : 0;
>>>>> +
>>>>> +out:
>>>>> +	return ret;
>>>>>  }
>>>>>  
>>>>>  static struct smp_operations bcm_smp_ops __initdata = {
>>>>>  	.smp_prepare_cpus	= bcm_smp_prepare_cpus,
>>>>> -	.smp_boot_secondary	= bcm_boot_secondary,
>>>>> +	.smp_boot_secondary	= kona_boot_secondary,
>>>>>  };
>>>>>  CPU_METHOD_OF_DECLARE(bcm_smp_bcm281xx, "brcm,bcm11351-cpu-method",
>>>>>  			&bcm_smp_ops);
>>>>> +
>>>>> +struct smp_operations nsp_smp_ops __initdata = {
>>>>> +	.smp_prepare_cpus	= bcm_smp_prepare_cpus,
>>>>> +	.smp_secondary_init	= nsp_secondary_init,
>>>>> +	.smp_boot_secondary	= nsp_boot_secondary,
>>>>> +};
>>>>> +CPU_METHOD_OF_DECLARE(bcm_smp_nsp, "brcm,bcm-nsp-smp", &nsp_smp_ops);
>>>>>
>>>>
>>> Thanks,
>>> Kapil
>>>
>>