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From:   Tomer Maimon <tmaimon77@gmail.com>
Date:   Thu, 26 Oct 2017 14:45:59 +0300
Message-ID: <CAP6Zq1i-6EJVH8=5-ejcsO_M-wsPQFhbQNCv7evCoiAjDRE74w@mail.gmail.com>
Subject: Re: [PATCH v7 1/3] arm: npcm: add basic support for Nuvoton BMCs
To:     Russell King - ARM Linux <linux@armlinux.org.uk>
Cc:     Brendan Higgins <brendanhiggins@google.com>,
        Avi Fishman <avifishman70@gmail.com>,
        Rob Herring <robh+dt@kernel.org>,
        Mark Rutland <mark.rutland@arm.com>,
        Rick Altherr <raltherr@google.com>,
        Florian Fainelli <f.fainelli@gmail.com>,
        devicetree <devicetree@vger.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        linux-arm-kernel@lists.infradead.org,
        OpenBMC Maillist <openbmc@lists.ozlabs.org>
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Sender: linux-kernel-owner@vger.kernel.org
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Hi Brendan,

Sorry for the delay,

On 21 October 2017 at 00:08, Russell King - ARM Linux
<linux@armlinux.org.uk> wrote:
> On Fri, Oct 20, 2017 at 01:57:47PM -0700, Brendan Higgins wrote:
>> On Fri, Oct 20, 2017 at 3:48 AM, Russell King - ARM Linux
>> <linux@armlinux.org.uk> wrote:
>> > On Thu, Oct 19, 2017 at 03:50:48PM -0700, Brendan Higgins wrote:
>> >> Adds basic support for the Nuvoton NPCM750 BMC.
>> >>
>> >> Signed-off-by: Brendan Higgins <brendanhiggins@google.com>
>> >> Reviewed-by: Tomer Maimon <tmaimon77@gmail.com>
>> >> Reviewed-by: Avi Fishman <avifishman70@gmail.com>
>> >> Tested-by: Tomer Maimon <tmaimon77@gmail.com>
>> >> Tested-by: Avi Fishman <avifishman70@gmail.com>
>> >> ---
>> >>  arch/arm/Kconfig             |  2 +
>> >>  arch/arm/Makefile            |  1 +
>> >>  arch/arm/mach-npcm/Kconfig   | 48 ++++++++++++++++++++++++
>> >>  arch/arm/mach-npcm/Makefile  |  3 ++
>> >>  arch/arm/mach-npcm/headsmp.S | 17 +++++++++
>> >>  arch/arm/mach-npcm/npcm7xx.c | 34 +++++++++++++++++
>> >>  arch/arm/mach-npcm/platsmp.c | 88 ++++++++++++++++++++++++++++++++++++++++++++
>> >>  7 files changed, 193 insertions(+)
>> >>  create mode 100644 arch/arm/mach-npcm/Kconfig
>> >>  create mode 100644 arch/arm/mach-npcm/Makefile
>> >>  create mode 100644 arch/arm/mach-npcm/headsmp.S
>> >>  create mode 100644 arch/arm/mach-npcm/npcm7xx.c
>> >>  create mode 100644 arch/arm/mach-npcm/platsmp.c
>> >>
>> >> diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
>> >> index 61a0cb15067e..05543f1cfbde 100644
>> >> --- a/arch/arm/Kconfig
>> >> +++ b/arch/arm/Kconfig
>> >> @@ -782,6 +782,8 @@ source "arch/arm/mach-netx/Kconfig"
>> >>
>> >>  source "arch/arm/mach-nomadik/Kconfig"
>> >>
>> >> +source "arch/arm/mach-npcm/Kconfig"
>> >> +
>> >>  source "arch/arm/mach-nspire/Kconfig"
>> >>
>> >>  source "arch/arm/plat-omap/Kconfig"
>> >> diff --git a/arch/arm/Makefile b/arch/arm/Makefile
>> >> index 47d3a1ab08d2..60ca50c7d762 100644
>> >> --- a/arch/arm/Makefile
>> >> +++ b/arch/arm/Makefile
>> >> @@ -191,6 +191,7 @@ machine-$(CONFIG_ARCH_MEDIATEK)           += mediatek
>> >>  machine-$(CONFIG_ARCH_MXS)           += mxs
>> >>  machine-$(CONFIG_ARCH_NETX)          += netx
>> >>  machine-$(CONFIG_ARCH_NOMADIK)               += nomadik
>> >> +machine-$(CONFIG_ARCH_NPCM)          += npcm
>> >>  machine-$(CONFIG_ARCH_NSPIRE)                += nspire
>> >>  machine-$(CONFIG_ARCH_OXNAS)         += oxnas
>> >>  machine-$(CONFIG_ARCH_OMAP1)         += omap1
>> >> diff --git a/arch/arm/mach-npcm/Kconfig b/arch/arm/mach-npcm/Kconfig
>> >> new file mode 100644
>> >> index 000000000000..21dfa8ce828f
>> >> --- /dev/null
>> >> +++ b/arch/arm/mach-npcm/Kconfig
>> >> @@ -0,0 +1,48 @@
>> >> +menuconfig ARCH_NPCM
>> >> +     bool "Nuvoton NPCM Architecture"
>> >> +     select ARCH_REQUIRE_GPIOLIB
>> >> +     select USE_OF
>> >> +     select PINCTRL
>> >> +     select PINCTRL_NPCM7XX
>> >> +
>> >> +if ARCH_NPCM
>> >> +
>> >> +comment "NPCMX50 CPU type"
>> >> +
>> >> +config CPU_NPCM750

I started the upstream process of NPCM7xx clocksource driver, I got
the following comment
https://www.spinics.net/lists/devicetree/msg197916.html

Is it possible to modify the the architecture configuration name to
ARCH_NPCM7XX.

>> >> +     depends on ARCH_NPCM && ARCH_MULTI_V7
>> >> +     bool "Support for NPCM750 BMC CPU (Poleg)"
>> >> +     select CACHE_L2X0
>> >> +     select CPU_V7
>> >> +     select ARM_GIC
>> >> +     select HAVE_SMP
>> >> +     select SMP
>> >> +     select SMP_ON_UP
>> >> +     select HAVE_ARM_SCU
>> >> +     select HAVE_ARM_TWD if SMP
>> >> +     select ARM_ERRATA_720789
>> >> +     select ARM_ERRATA_754322
>> >> +     select ARM_ERRATA_764369
>> >> +     select ARM_ERRATA_794072
>> >> +     select PL310_ERRATA_588369
>> >> +     select PL310_ERRATA_727915
>> >> +     select USB_EHCI_ROOT_HUB_TT
>> >> +     select USB_ARCH_HAS_HCD
>> >> +     select USB_ARCH_HAS_EHCI
>> >> +     select USB_EHCI_HCD
>> >> +     select USB_ARCH_HAS_OHCI
>> >> +     select USB_OHCI_HCD
>> >> +     select USB
>> >> +     select FIQ
>> >> +     select CPU_USE_DOMAINS
>> >> +     select GENERIC_CLOCKEVENTS
>> >> +     select CLKDEV_LOOKUP
>> >> +     select COMMON_CLK if OF
>> >> +     select NPCM750_TIMER
>> >> +     select MFD_SYSCON
>> >> +     help
>> >> +       Support for NPCM750 BMC CPU (Poleg).
>> >> +
>> >> +       Nuvoton NPCM750 BMC based on the Cortex A9.
>> >> +
>> >> +endif
>> >> diff --git a/arch/arm/mach-npcm/Makefile b/arch/arm/mach-npcm/Makefile
>> >> new file mode 100644
>> >> index 000000000000..78416055b854
>> >> --- /dev/null
>> >> +++ b/arch/arm/mach-npcm/Makefile
>> >> @@ -0,0 +1,3 @@
>> >> +AFLAGS_headsmp.o             += -march=armv7-a
>> >> +
>> >> +obj-$(CONFIG_CPU_NPCM750)    += npcm7xx.o platsmp.o headsmp.o
>> >> diff --git a/arch/arm/mach-npcm/headsmp.S b/arch/arm/mach-npcm/headsmp.S
>> >> new file mode 100644
>> >> index 000000000000..9fccbbd49ed4
>> >> --- /dev/null
>> >> +++ b/arch/arm/mach-npcm/headsmp.S
>> >> @@ -0,0 +1,17 @@
>> >> +/*
>> >> + * Copyright 2017 Google, Inc.
>> >> + *
>> >> + * 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/linkage.h>
>> >> +#include <linux/init.h>
>> >> +#include <asm/assembler.h>
>> >> +
>> >> +ENTRY(npcm7xx_secondary_startup)
>> >> +     safe_svcmode_maskall r0
>> >> +
>> >> +     b       secondary_startup
>> >> +ENDPROC(npcm7xx_secondary_startup)
>> >
>> > Why do you need this?  The switch to svc mode is already handled by
>> > secondary_startup.
>>
>> Florian Fainelli already brought this up:
>> https://www.spinics.net/lists/arm-kernel/msg605126.html
>> Without this the kernel complains that the core is started in
>> "wrong/inconsistent mode":
>
> The solution would be a comment to indicate why it's necessary :)
>
>>
>> SMP: Total of 2 processors activated (398.13 BogoMIPS).
>> CPU: WARNING: CPU(s) started in wrong/inconsistent modes (primary CPU
>> mode 0x13)
>> CPU: This may indicate a broken bootloader or firmware.
>>
>> >
>> >> diff --git a/arch/arm/mach-npcm/npcm7xx.c b/arch/arm/mach-npcm/npcm7xx.c
>> >> new file mode 100644
>> >> index 000000000000..132e9d587857
>> >> --- /dev/null
>> >> +++ b/arch/arm/mach-npcm/npcm7xx.c
>> >> @@ -0,0 +1,34 @@
>> >> +/*
>> >> + * Copyright (c) 2017 Nuvoton Technology corporation.
>> >> + * Copyright 2017 Google, Inc.
>> >> + *
>> >> + * 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/types.h>
>> >> +#include <asm/mach/arch.h>
>> >> +#include <asm/mach-types.h>
>> >> +#include <asm/mach/map.h>
>> >> +#include <asm/hardware/cache-l2x0.h>
>> >> +
>> >> +#define NPCM7XX_AUX_VAL (L310_AUX_CTRL_INSTR_PREFETCH |                             \
>> >> +                      L310_AUX_CTRL_DATA_PREFETCH |                         \
>> >> +                      L310_AUX_CTRL_NS_LOCKDOWN |                           \
>> >> +                      L310_AUX_CTRL_CACHE_REPLACE_RR |                      \
>> >> +                      L2C_AUX_CTRL_SHARED_OVERRIDE |                        \
>> >> +                      L310_AUX_CTRL_FULL_LINE_ZERO)
>> >
>> > Do you really need all these flags?
>>
>> Tomer, Avi, do we need these? I got this from the original version of
>> the driver.
>
> The l2c driver manages L310_AUX_CTRL_FULL_LINE_ZERO itself, so you
> shouldn't specify that.
>
> L2C_AUX_CTRL_SHARED_OVERRIDE is managed via the "arm,shared-override"
> DT property, so you should use that in DT instead.
>
> Prefetching needs the prefetch control register configured to tune the
> prefetching - that's platform specific so the l2c driver doesn't touch
> it (it expects firmware to have configured it.)  If firmware needs to
> configure that, it might as well configure the flags too as they're
> shared into that very same register.  If not, I think the l2c prefetch
> register defaults to a very small prefetch, and is probably not worth
> setting the enable bits without configuring the depth of prefetch.

Yes, we do it in the firmware.

>
> L310_AUX_CTRL_NS_LOCKDOWN is always enabled by the l2c driver, so
> shouldn't be necessary.
>
> So that leaves only L310_AUX_CTRL_CACHE_REPLACE_RR.
>

You dont need to add L310_AUX_CTRL_CACHE_REPLACE_RR to the l2c aux value.

>>
>> >
>> >> +
>> >> +static const char *const npcm7xx_dt_match[] = {
>> >> +     "nuvoton,npcm750",
>> >> +     NULL
>> >> +};
>> >> +
>> >> +DT_MACHINE_START(NPCM7XX_DT, "NPCMX50 Chip family")
>> >> +     .atag_offset    = 0x100,
>> >> +     .dt_compat      = npcm7xx_dt_match,
>> >> +     .l2c_aux_val    = NPCM7XX_AUX_VAL,
>> >> +     .l2c_aux_mask   = ~NPCM7XX_AUX_VAL,
>> >> +MACHINE_END
>> >> diff --git a/arch/arm/mach-npcm/platsmp.c b/arch/arm/mach-npcm/platsmp.c
>> >> new file mode 100644
>> >> index 000000000000..450e83c3c531
>> >> --- /dev/null
>> >> +++ b/arch/arm/mach-npcm/platsmp.c
>> >> @@ -0,0 +1,88 @@
>> >> +/*
>> >> + * Copyright 2017 Google, Inc.
>> >> + *
>> >> + * 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.
>> >> + */
>> >> +
>> >> +#define pr_fmt(fmt) "PLATSMP: " fmt
>> >
>> > Maybe something more descriptive?
>> >
>> >> +
>> >> +#include <linux/delay.h>
>> >> +#include <linux/device.h>
>> >> +#include <linux/smp.h>
>> >> +#include <linux/io.h>
>> >> +#include <linux/of.h>
>> >> +#include <linux/of_device.h>
>> >> +#include <linux/of_platform.h>
>> >> +#include <linux/of_address.h>
>> >> +#include <asm/cacheflush.h>
>> >> +#include <asm/smp.h>
>> >> +#include <asm/smp_plat.h>
>> >> +#include <asm/smp_scu.h>
>> >> +
>> >> +#define NPCM7XX_SCRPAD_REG 0x13c
>> >> +
>> >> +extern void npcm7xx_secondary_startup(void);
>> >> +
>> >> +static int npcm7xx_smp_boot_secondary(unsigned int cpu,
>> >> +                                   struct task_struct *idle)
>> >> +{
>> >> +     struct device_node *gcr_np;
>> >> +     void __iomem *gcr_base;
>> >> +     int ret = 0;
>> >> +
>> >> +     gcr_np = of_find_compatible_node(NULL, NULL, "nuvoton,npcm750-gcr");
>> >> +     if (!gcr_np) {
>> >> +             pr_err("no gcr device node\n");
>> >> +             ret = -EFAULT;
>> >
>> > EFAULT is used for bad userspace addresses, it should not be used for
>> > other stuff - and a missing node is certainly not a "Bad address".
>> >
>> >> +             goto out;
>> >> +     }
>> >> +     gcr_base = of_iomap(gcr_np, 0);
>> >> +     if (!gcr_base) {
>> >> +             pr_err("could not iomap gcr at: 0x%p\n", gcr_base);
>> >> +             ret = -EFAULT;
>> >
>> > This is more -ENOMEM.
>> >
>> >> +             goto out;
>> >> +     }
>> >> +
>> >> +     /* give boot ROM kernel start address. */
>> >> +     iowrite32(__pa_symbol(npcm7xx_secondary_startup), gcr_base +
>> >> +               NPCM7XX_SCRPAD_REG);
>> >> +     /* make sure npcm7xx_secondary_startup is seen by all observers. */
>> >> +     smp_wmb();
>> >
>> > I think you mean "make sure the previous write is seen by all observers".
>> > However, doesn't "dsb_sev()" already do that?
>> >
>> >> +     dsb_sev();
>> >> +     /* make sure write buffer is drained */
>> >> +     mb();
>> >
>> > This looks over the top.
>> >
>> >> +
>> >> +     iounmap(gcr_base);
>> >> +out:
>> >> +     return ret;
>> >> +}
>> >> +
>> >> +static void __init npcm7xx_smp_prepare_cpus(unsigned int max_cpus)
>> >> +{
>> >> +     struct device_node *scu_np;
>> >> +     void __iomem *scu_base;
>> >> +
>> >> +     scu_np = of_find_compatible_node(NULL, NULL, "arm,cortex-a9-scu");
>> >> +     if (!scu_np) {
>> >> +             pr_err("no scu device node\n");
>> >> +             return;
>> >> +     }
>> >> +     scu_base = of_iomap(scu_np, 0);
>> >> +     if (!scu_base) {
>> >> +             pr_err("could not iomap scu at: 0x%p\n", scu_base);
>> >> +             return;
>> >> +     }
>> >> +
>> >> +     scu_enable(scu_base);
>> >> +
>> >> +     iounmap(scu_base);
>> >> +}
>> >> +
>> >> +static struct smp_operations npcm7xx_smp_ops __initdata = {
>> >> +     .smp_prepare_cpus = npcm7xx_smp_prepare_cpus,
>> >> +     .smp_boot_secondary = npcm7xx_smp_boot_secondary,
>> >> +};
>> >> +
>> >> +CPU_METHOD_OF_DECLARE(npcm7xx_smp, "nuvoton,npcm7xx-smp", &npcm7xx_smp_ops);
>> >> --
>> >> 2.15.0.rc0.271.g36b669edcc-goog
>> >>
>> >
>> > --
>> > RMK's Patch system: http://www.armlinux.org.uk/developer/patches/
>> > FTTC broadband for 0.8mile line in suburbia: sync at 8.8Mbps down 630kbps up
>> > According to speedtest.net: 8.21Mbps down 510kbps up
>
> --
> RMK's Patch system: http://www.armlinux.org.uk/developer/patches/
> FTTC broadband for 0.8mile line in suburbia: sync at 8.8Mbps down 630kbps up
> According to speedtest.net: 8.21Mbps down 510kbps up

Thanks,

Tomer

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