[PATCH 7/9] RISC-V: add initial LiteX SoC support
Ahmad Fatoum
a.fatoum at pengutronix.de
Wed May 5 03:16:01 PDT 2021
Hello Antony,
On 05.05.21 12:08, Antony Pavlov wrote:
> LiteX is a Migen-based System on Chip, supporting softcore
> VexRiscv CPU, a 32-bits Linux Capable RISC-V CPU.
>
> See https://github.com/enjoy-digital/litex and
> https://github.com/litex-hub/linux-on-litex-vexriscv
> for details.
>
> Signed-off-by: Antony Pavlov <antonynpavlov at gmail.com>
> ---
> arch/riscv/Kconfig | 9 ++
> arch/riscv/Makefile | 1 +
> arch/riscv/dts/litex_soc_linux.dtsi | 49 +++++++
> arch/riscv/mach-litex/Kconfig | 8 ++
> arch/riscv/mach-litex/Makefile | 3 +
> arch/riscv/mach-litex/include/mach/debug_ll.h | 124 ++++++++++++++++++
> 6 files changed, 194 insertions(+)
>
> diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
> index c0583f3153..40dfd7dd93 100644
> --- a/arch/riscv/Kconfig
> +++ b/arch/riscv/Kconfig
> @@ -34,6 +34,14 @@ config MACH_ERIZO
> select RISCV_M_MODE
> select RISCV_TIMER
>
> +config MACH_LITEX
> + bool "litex family"
> + select ARCH_RV32I
> + select HAS_DEBUG_LL
> + select HAS_NMON
> + select USE_COMPRESSED_DTB
> + select RISCV_SBI
> +
> config MACH_VIRT
> bool "virt family"
> select BOARD_RISCV_GENERIC_DT
> @@ -83,6 +91,7 @@ config 64BIT
> select PHYS_ADDR_T_64BIT
>
> source "arch/riscv/mach-erizo/Kconfig"
> +source "arch/riscv/mach-litex/Kconfig"
>
> config BOARD_RISCV_GENERIC_DT
> select BOARD_GENERIC_DT
> diff --git a/arch/riscv/Makefile b/arch/riscv/Makefile
> index aba4526bba..bc22786368 100644
> --- a/arch/riscv/Makefile
> +++ b/arch/riscv/Makefile
> @@ -20,6 +20,7 @@ cflags-y += $(riscv-cflags-y)
> LDFLAGS_barebox += -nostdlib
>
> machine-$(CONFIG_MACH_ERIZO) := erizo
> +machine-$(CONFIG_MACH_LITEX) := litex
Could you rebase on barebox next?
I dropped machine directories for RISC-V. They were only
used for <mach/debug_ll.h> and there is an <asm/debug_ll.h>
now that can be extended instead.
This reduces boilerplate and allows building all RISC-V
images in one go.
> machine-$(CONFIG_MACH_VIRT) := virt
>
> LDFLAGS_barebox += $(riscv-ldflags-y)
> diff --git a/arch/riscv/dts/litex_soc_linux.dtsi b/arch/riscv/dts/litex_soc_linux.dtsi
> new file mode 100644
> index 0000000000..32382b8dc2
> --- /dev/null
> +++ b/arch/riscv/dts/litex_soc_linux.dtsi
Is "linux" a well-nown LiteX configuration?
Otherwise would maybe litex-vexrisc.dtsi be a better name?
> @@ -0,0 +1,49 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +
> +/dts-v1/;
> +
> +/ {
> + compatible = "litex,vexriscv-soc-linux";
> +
> + #address-cells = <1>;
> + #size-cells = <1>;
> +
> + cpus {
> + #address-cells = <1>;
> + #size-cells = <0>;
> +
> + timebase-frequency = <100000000>; // 100 MHz
> +
> + cpu at 0 {
> + device_type = "cpu";
> + compatible = "spinalhdl,vexriscv", "riscv";
> + reg = <0>;
> + };
> + };
> +
> + uart0: serial at f0001000 {
> + compatible = "litex,uart";
> + reg = <0xf0001000 0x18>;
> + status = "disabled";
> + };
> +
> + mac0: mac at f0009000 {
> + compatible = "litex,liteeth";
> + reg = <0xf0009000 0x7c /* base */
> + 0xf0009800 0x0a /* mdio_base */
> + 0xb0000000 0x2000>; /* buf_base */
> + tx-fifo-depth = <2>;
> + rx-fifo-depth = <2>;
> + status = "disabled";
> + };
> +
> + spi0: spi at f000b800 {
> + compatible = "litex,spiflash";
> +
> + #address-cells = <1>;
> + #size-cells = <0>;
> +
> + reg = <0xf000b800 0x100>;
> + status = "disabled";
> + };
> +};
> diff --git a/arch/riscv/mach-litex/Kconfig b/arch/riscv/mach-litex/Kconfig
> new file mode 100644
> index 0000000000..19d5927e44
> --- /dev/null
> +++ b/arch/riscv/mach-litex/Kconfig
> @@ -0,0 +1,8 @@
> +if MACH_LITEX
> +
> +choice
> + prompt "Board type"
> +
> +endchoice
> +
> +endif
> diff --git a/arch/riscv/mach-litex/Makefile b/arch/riscv/mach-litex/Makefile
> new file mode 100644
> index 0000000000..d9c51e74c3
> --- /dev/null
> +++ b/arch/riscv/mach-litex/Makefile
> @@ -0,0 +1,3 @@
> +# just to build a built-in.o. Otherwise compilation fails when no o-files is
> +# created.
> +obj- += dummy.o
> diff --git a/arch/riscv/mach-litex/include/mach/debug_ll.h b/arch/riscv/mach-litex/include/mach/debug_ll.h
> new file mode 100644
> index 0000000000..df7032716d
> --- /dev/null
> +++ b/arch/riscv/mach-litex/include/mach/debug_ll.h
> @@ -0,0 +1,124 @@
> +/* SPDX-License-Identifier: GPL-2.0-only */
> +/*
> + * Copyright (C) 2019 Antony Pavlov <antonynpavlov at gmail.com>
> + *
> + * This file is part of barebox.
> + *
> + * 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.
> + *
> + */
> +
> +#ifndef __MACH_LITEX_DEBUG_LL__
> +#define __MACH_LITEX_DEBUG_LL__
> +
> +/** @file
> + * This File contains declaration for early output support
> + */
> +
> +#include <linux/kconfig.h>
> +
> +#define DEBUG_LL_UART_ADDR 0xf0001000
> +#define UART_RXTX 0x00
> +#define UART_TXFULL 0x04
> +#define UART_RXEMPTY 0x08
> +#define UART_EV_PENDING 0x10
> +#define UART_EV_RX (1 << 1)
> +#define UART_EV_ENABLE 0x14
> +
> +
> +#ifndef __ASSEMBLY__
> +
> +/*
> + * C macros
> + */
> +
> +#include <asm/io.h>
> +
> +static inline void PUTC_LL(char ch)
> +{
> +#ifdef CONFIG_DEBUG_LL
> + /* wait for space */
> + while (__raw_readb((u8 *)DEBUG_LL_UART_ADDR + UART_TXFULL))
> + ;
> +
> + __raw_writeb(ch, (u8 *)DEBUG_LL_UART_ADDR + UART_RXTX);
> +#endif /* CONFIG_DEBUG_LL */
> +}
> +#else /* __ASSEMBLY__ */
> +/*
> + * Macros for use in assembly language code
> + */
> +
> +/*
> + * output a character in a0
> + */
> +.macro debug_ll_outc_a0
> +#ifdef CONFIG_DEBUG_LL
> +
> + li t0, DEBUG_LL_UART_ADDR
> +
> +201:
> + lbu t1, UART_TXFULL(t0) /* uart tx full ? */
> + andi t1, t1, 0xff
> + bnez t1, 201b /* try again */
> +
> + sb a0, UART_RXTX(t0) /* write the character */
> +
> +#endif /* CONFIG_DEBUG_LL */
> +.endm
> +
> +/*
> + * output a character
> + */
> +.macro debug_ll_outc chr
> +#ifdef CONFIG_DEBUG_LL
> + li a0, \chr
> + debug_ll_outc_a0
> +#endif /* CONFIG_DEBUG_LL */
> +.endm
> +
> +/*
> + * check character in input buffer
> + * return value:
> + * v0 = 0 no character in input buffer
> + * v0 != 0 character in input buffer
> + */
> +.macro debug_ll_tstc
> +#ifdef CONFIG_DEBUG_LL
> + li t0, DEBUG_LL_UART_ADDR
> +
> + /* get line status and check for data present */
> + lbu s0, UART_RXEMPTY(t0)
> + bnez s0, 243f
> + li s0, 1
> + j 244f
> +243: li s0, 0
> +244: nop
> +#endif /* CONFIG_DEBUG_LL */
> +.endm
> +
> +/*
> + * get character to v0
> + */
> +.macro debug_ll_getc
> +#ifdef CONFIG_DEBUG_LL
> +
> +204:
> + debug_ll_tstc
> +
> + /* try again */
> + beqz s0, 204b
> +
> + /* read a character */
> + lb s0, UART_RXTX(t0)
> + li t1, UART_EV_RX
> + sb t1, UART_EV_PENDING(t0)
> +
> +#endif /* CONFIG_DEBUG_LL */
> +.endm
> +#endif /* __ASSEMBLY__ */
> +
> +#endif /* __MACH_LITEX_DEBUG_LL__ */
Given that we jump into C very early now, do we still need
the assembly debug_ll helpers?
Cheers,
Ahmad
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