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Message-ID: <CACPK8XcGhxTq7QGeub2rAEtGSyrOmnobspVJfhE5YmB6MQRM9w@mail.gmail.com>
Date: Tue, 13 Feb 2018 12:29:32 +1030
From: Joel Stanley <joel@....id.au>
To: Brendan Higgins <brendanhiggins@...gle.com>,
Jeremy Kerr <jk@...abs.org>
Cc: Russell King <linux@...linux.org.uk>,
Avi Fishman <avifishman70@...il.com>,
Tomer Maimon <tmaimon77@...il.com>,
Patrick Venture <venture@...gle.com>,
Nancy Yuen <yuenn@...gle.com>,
OpenBMC Maillist <openbmc@...ts.ozlabs.org>,
Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
Linux ARM <linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCH v1 1/2] arm: npcm: add low-level debug support for NPCM7XX
Hi Brendan,
On Tue, Feb 13, 2018 at 7:28 AM, Brendan Higgins
<brendanhiggins@...gle.com> wrote:
> Enable low-level debug support for Nuvoton NPCM7XX family by adding the
> debug port definitions for the SoC.
When playing with the Poleg boards at the recent OpenBMC hackathon
Jeremy discovered that the UART is a normal-ish 8250, with a custom
divisor and a few extra bits to be set.
I found that we can us the generic 8250 low level debugging support
just fine. This is because u-boot sets up the divisor settings for us
(as you've assumed with your version here), and from there it's just
reading/writing characters.
Assuming you can reproduce our results, I suggest we drop these
patches in favour of adding the correct configuration the Poleg.
Cheers,
Joel
>
> Signed-off-by: Brendan Higgins <brendanhiggins@...gle.com>
> ---
> arch/arm/Kconfig.debug | 11 +++++++++++
> arch/arm/include/debug/npcm7xx.S | 30 ++++++++++++++++++++++++++++++
> 2 files changed, 41 insertions(+)
> create mode 100644 arch/arm/include/debug/npcm7xx.S
>
> diff --git a/arch/arm/Kconfig.debug b/arch/arm/Kconfig.debug
> index 447629d89884..d8f925cb8872 100644
> --- a/arch/arm/Kconfig.debug
> +++ b/arch/arm/Kconfig.debug
> @@ -595,6 +595,12 @@ choice
> Say Y here if you want kernel low-level debugging support
> on Hilscher NetX based platforms.
>
> + config DEBUG_NPCM7XX_UART
> + bool "Kernel low-level debugging messages via Nuvoton NPCMx50 UART"
> + help
> + Say Y here if you want kernel low-level debugging support
> + on Nuvoton based platforms.
> +
> config DEBUG_NOMADIK_UART
> bool "Kernel low-level debugging messages via NOMADIK UART"
> depends on ARCH_NOMADIK
> @@ -1444,6 +1450,7 @@ config DEBUG_LL_INCLUDE
> default "debug/ks8695.S" if DEBUG_KS8695_UART
> default "debug/msm.S" if DEBUG_QCOM_UARTDM
> default "debug/netx.S" if DEBUG_NETX_UART
> + default "debug/npcm7xx.S" if DEBUG_NPCM7XX_UART
> default "debug/omap2plus.S" if DEBUG_OMAP2PLUS_UART
> default "debug/renesas-scif.S" if DEBUG_R7S72100_SCIF2
> default "debug/renesas-scif.S" if DEBUG_RCAR_GEN1_SCIF0
> @@ -1481,6 +1488,7 @@ config DEBUG_UART_8250
> config DEBUG_UART_PHYS
> hex "Physical base address of debug UART"
> default 0x00100a00 if DEBUG_NETX_UART
> + default 0xf0004000 if DEBUG_NPCM7XX_UART
> default 0x01c20000 if DEBUG_DAVINCI_DMx_UART0
> default 0x01c28000 if DEBUG_SUNXI_UART0
> default 0x01c28400 if DEBUG_SUNXI_UART1
> @@ -1589,6 +1597,7 @@ config DEBUG_UART_PHYS
> DEBUG_LL_UART_EFM32 || \
> DEBUG_UART_8250 || DEBUG_UART_PL01X || DEBUG_MESON_UARTAO || \
> DEBUG_NETX_UART || \
> + DEBUG_NPCM7XX_UART || \
> DEBUG_QCOM_UARTDM || DEBUG_R7S72100_SCIF2 || \
> DEBUG_RCAR_GEN1_SCIF0 || DEBUG_RCAR_GEN1_SCIF2 || \
> DEBUG_RCAR_GEN2_SCIF0 || DEBUG_RCAR_GEN2_SCIF2 || \
> @@ -1605,6 +1614,7 @@ config DEBUG_UART_VIRT
> default 0xc8821000 if DEBUG_RV1108_UART1
> default 0xc8912000 if DEBUG_RV1108_UART0
> default 0xe0000a00 if DEBUG_NETX_UART
> + default 0xf0001000 if DEBUG_NPCM7XX_UART
> default 0xe0010fe0 if ARCH_RPC
> default 0xf0000be0 if ARCH_EBSA110
> default 0xf0010000 if DEBUG_ASM9260_UART
> @@ -1695,6 +1705,7 @@ config DEBUG_UART_VIRT
> depends on DEBUG_LL_UART_8250 || DEBUG_LL_UART_PL01X || \
> DEBUG_UART_8250 || DEBUG_UART_PL01X || DEBUG_MESON_UARTAO || \
> DEBUG_NETX_UART || \
> + DEBUG_NPCM7XX_UART || \
> DEBUG_QCOM_UARTDM || DEBUG_S3C24XX_UART || \
> DEBUG_S3C64XX_UART || \
> DEBUG_BCM63XX_UART || DEBUG_ASM9260_UART || \
> diff --git a/arch/arm/include/debug/npcm7xx.S b/arch/arm/include/debug/npcm7xx.S
> new file mode 100644
> index 000000000000..d08e14e73d79
> --- /dev/null
> +++ b/arch/arm/include/debug/npcm7xx.S
> @@ -0,0 +1,30 @@
> +// SPDX-License-Identifier: GPL-2.0
> +// Copyright 2018 Google, Inc.
> +// This is heavily based on arch/arm/include/debug/at91.S
> +
> +#define NPCM7XX_SR (0x14) /* Status Register */
> +#define NPCM7XX_THR (0x00) /* Transmitter Holding Register */
> +#define NPCM7XX_TXRDY (1 << 6) /* Transmitter Ready */
> +#define NPCM7XX_TXEMPTY (1 << 6) /* Transmitter Empty */
> +
> + .macro addruart, rp, rv, tmp
> + ldr \rp, =CONFIG_DEBUG_UART_PHYS @ System peripherals (phys)
> + ldr \rv, =CONFIG_DEBUG_UART_VIRT @ System peripherals (virt)
> + .endm
> +
> + .macro senduart,rd,rx
> + strb \rd, [\rx, #(NPCM7XX_THR)] @ Write to Transmit Holding Reg
> + .endm
> +
> + .macro waituart,rd,rx
> +1001: ldr \rd, [\rx, #(NPCM7XX_SR)] @ Read Status Register
> + tst \rd, #NPCM7XX_TXRDY @ TXRDY = 1 when ready to tx
> + beq 1001b
> + .endm
> +
> + .macro busyuart,rd,rx
> +1001: ldr \rd, [\rx, #(NPCM7XX_SR)] @ Read Status Register
> + tst \rd, #NPCM7XX_TXEMPTY @ TXEMPTY = 1 when tx complete
> + beq 1001b
> + .endm
> +
> --
> 2.16.0.rc1.238.g530d649a79-goog
>
>
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