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From:   Rob Herring <robh+dt@kernel.org>
Date:   Mon, 27 Nov 2017 13:07:56 -0600
Message-ID: <CAL_Jsq+c4vt4-royBuTxAj+AY2wFHMugyyy41S5YP-QXyF2gbQ@mail.gmail.com>
Subject: Re: [PATCH v2 22/35] nds32: Device tree support
To:     Greentime Hu <green.hu@gmail.com>
Cc:     greentime@andestech.com,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        Arnd Bergmann <arnd@arndb.de>,
        "linux-arch@vger.kernel.org" <linux-arch@vger.kernel.org>,
        Thomas Gleixner <tglx@linutronix.de>,
        Jason Cooper <jason@lakedaemon.net>,
        Marc Zyngier <marc.zyngier@arm.com>,
        netdev <netdev@vger.kernel.org>, deanbo422@gmail.com,
        "devicetree@vger.kernel.org" <devicetree@vger.kernel.org>,
        Al Viro <viro@zeniv.linux.org.uk>,
        David Howells <dhowells@redhat.com>,
        Will Deacon <will.deacon@arm.com>,
        Daniel Lezcano <daniel.lezcano@linaro.org>,
        "linux-serial@vger.kernel.org" <linux-serial@vger.kernel.org>,
        Vincent Chen <vincentc@andestech.com>
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On Mon, Nov 27, 2017 at 6:28 AM, Greentime Hu <green.hu@gmail.com> wrote:
> From: Greentime Hu <greentime@andestech.com>
>
> This patch adds support for device tree.
>
> Signed-off-by: Vincent Chen <vincentc@andestech.com>
> Signed-off-by: Greentime Hu <greentime@andestech.com>
> ---
>  arch/nds32/boot/dts/Makefile   |    8 ++++++
>  arch/nds32/boot/dts/ae3xx.dts  |   55 ++++++++++++++++++++++++++++++++++++
>  arch/nds32/boot/dts/ag101p.dts |   60 ++++++++++++++++++++++++++++++++++++++++
>  arch/nds32/kernel/devtree.c    |   45 ++++++++++++++++++++++++++++++
>  4 files changed, 168 insertions(+)
>  create mode 100644 arch/nds32/boot/dts/Makefile
>  create mode 100644 arch/nds32/boot/dts/ae3xx.dts
>  create mode 100644 arch/nds32/boot/dts/ag101p.dts
>  create mode 100644 arch/nds32/kernel/devtree.c
>
> diff --git a/arch/nds32/boot/dts/Makefile b/arch/nds32/boot/dts/Makefile
> new file mode 100644
> index 0000000..d31faa8
> --- /dev/null
> +++ b/arch/nds32/boot/dts/Makefile
> @@ -0,0 +1,8 @@
> +ifneq '$(CONFIG_NDS32_BUILTIN_DTB)' '""'

Built-in dtb's are really for legacy bootloader cases where the
bootloader doesn't understand dtbs. Do you have that here?

Plus, I don't see any code here to handle the built-in dtb.

> +BUILTIN_DTB := $(patsubst "%",%,$(CONFIG_NDS32_BUILTIN_DTB)).dtb.o
> +else
> +BUILTIN_DTB :=
> +endif
> +obj-$(CONFIG_OF) += $(BUILTIN_DTB)
> +
> +clean-files := *.dtb *.dtb.S
> diff --git a/arch/nds32/boot/dts/ae3xx.dts b/arch/nds32/boot/dts/ae3xx.dts
> new file mode 100644
> index 0000000..4181060
> --- /dev/null
> +++ b/arch/nds32/boot/dts/ae3xx.dts
> @@ -0,0 +1,55 @@
> +/dts-v1/;
> +/ {
> +       compatible = "nds32 ae3xx";

This compatible needs to be documented and is not valid. Needs to be
in the form "vendor,board-name" without spaces.

> +       #address-cells = <1>;
> +       #size-cells = <1>;
> +       interrupt-parent = <&intc>;
> +
> +       chosen {
> +               bootargs = "earlycon console=ttyS0,38400n8 debug loglevel=7";
> +               stdout-path = &serial0;
> +       };
> +
> +       memory@0 {
> +               device_type = "memory";
> +               reg = <0x00000000 0x40000000>;
> +       };
> +
> +       cpu {
> +               device_type = "cpu";
> +               compatible = "andestech,n13", "andestech,nds32v3";
> +               clock-frequency = <60000000>;
> +       };
> +
> +       intc: interrupt-controller {
> +               compatible = "andestech,ativic32";
> +               #interrupt-cells = <1>;
> +               interrupt-controller;
> +       };
> +
> +       serial0: serial@f0300000 {
> +               compatible = "andestech,uart16550", "ns16550a";
> +               reg = <0xf0300000 0x1000>;
> +               interrupts = <8>;
> +               clock-frequency = <14745600>;
> +               reg-shift = <2>;
> +               reg-offset = <32>;
> +               no-loopback-test = <1>;
> +       };
> +
> +       timer0: timer@f0400000 {
> +               compatible = "andestech,atcpit100";
> +               reg = <0xf0400000 0x1000>;
> +               interrupts = <2>;
> +               clock-frequency = <30000000>;
> +               cycle-count-offset = <0x38>;
> +               cycle-count-down;
> +       };
> +
> +       mac0: mac@e0100000 {

ethernet@...

> +               compatible = "andestech,atmac100";
> +               reg = <0xe0100000 0x1000>;
> +               interrupts = <18>;
> +       };
> +
> +};
> diff --git a/arch/nds32/boot/dts/ag101p.dts b/arch/nds32/boot/dts/ag101p.dts
> new file mode 100644
> index 0000000..f1cb540
> --- /dev/null
> +++ b/arch/nds32/boot/dts/ag101p.dts
> @@ -0,0 +1,60 @@
> +/dts-v1/;
> +/ {
> +       compatible = "nds32 ag101p";

Same here.

> +       #address-cells = <1>;
> +       #size-cells = <1>;
> +       interrupt-parent = <&intc>;
> +
> +       chosen {
> +               bootargs = "earlycon console=ttyS0,38400n8 debug loglevel=7";
> +               stdout-path = &serial0;
> +       };
> +
> +       memory@0 {
> +               device_type = "memory";
> +               reg = <0x00000000 0x40000000>;
> +       };
> +
> +       cpu@0 {
> +               device_type = "cpu";
> +               compatible = "andestech,n13";
> +               clock-frequency = <60000000>;
> +               next-level-cache = <&L2>;
> +       };
> +
> +       intc: interrupt-controller {
> +               compatible = "andestech,ativic32";
> +               #interrupt-cells = <2>;
> +               interrupt-controller;
> +       };
> +
> +       serial0: serial@99600000 {
> +               compatible = "andestech,uart16550", "ns16550a";
> +               reg = <0x99600000 0x1000>;
> +               interrupts = <7 4>;
> +               clock-frequency = <14745600>;
> +               reg-shift = <2>;
> +               no-loopback-test = <1>;
> +       };
> +
> +       timer0: timer@98400000 {
> +               compatible = "andestech,atftmr010";
> +               reg = <0x98400000 0x1000>;
> +               interrupts = <19 4>;
> +               clock-frequency = <15000000>;
> +               cycle-count-offset = <0x20>;
> +       };
> +
> +       mac0: mac@90900000 {
> +               compatible = "andestech,atmac100";
> +               reg = <0x90900000 0x1000>;
> +               interrupts = <25 4>;
> +       };
> +
> +       L2: l2-cache {
> +               compatible = "andestech,atl2c";
> +               reg = <0x90f00000 0x1000>;
> +               cache-unified;
> +               cache-level = <2>;
> +       };
> +};
> diff --git a/arch/nds32/kernel/devtree.c b/arch/nds32/kernel/devtree.c
> new file mode 100644
> index 0000000..2af0f1c
> --- /dev/null
> +++ b/arch/nds32/kernel/devtree.c
> @@ -0,0 +1,45 @@
> +/*
> + * Copyright (C) 2005-2017 Andes Technology Corporation
> + *
> + * 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.
> + *
> + * 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.
> + *
> + * You should have received a copy of the GNU General Public License
> + * along with this program.  If not, see <http://www.gnu.org/licenses/>.
> + */
> +
> +#include <linux/memblock.h>
> +#include <linux/of_fdt.h>
> +#include <linux/bootmem.h>
> +
> +void __init early_init_dt_add_memory_arch(u64 base, u64 size)
> +{
> +       size &= PAGE_MASK;
> +       memblock_add_node(base, size, 0);
> +}
> +
> +void *__init early_init_dt_alloc_memory_arch(u64 size, u64 align)
> +{
> +       return alloc_bootmem_align(size, align);
> +}

You should be able to use the default functions for these 2.

> +
> +void __init early_init_devtree(void *params)
> +{
> +       if (!params || !early_init_dt_scan(params)) {
> +               pr_crit("\n"
> +                       "Error: invalid device tree blob at (virtual address 0x%p)\n"
> +                       "The dtb must be 8-byte aligned and must not exceed 8 KB in size\n"

Why the size limit? That's pretty small for a DT.

> +                       "\nPlease check your bootloader.", params);
> +
> +               while (true)
> +                       cpu_relax();

Might as well use BUG_ON here if you're not going to continue. It's
generally better to WARN and continue on otherwise the messages aren't
visible until the console is up. However, if you have DT errors this
early, there's not much you can really do here.

> +       }
> +
> +       dump_stack_set_arch_desc("%s (DT)", of_flat_dt_get_machine_name());
> +}
> --
> 1.7.9.5
>

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