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Re: [PATCH V4 2/2] xen/arm: Add i.MX lpuart early printk support



Hi,

On 11/04/2022 07:24, Michal Orzel wrote:
On 08.04.2022 16:09, Peng Fan (OSS) wrote:
From: Peng Fan <peng.fan@xxxxxxx>

Signed-off-by: Peng Fan <peng.fan@xxxxxxx>
---
  xen/arch/arm/Kconfig.debug              | 14 +++++++
  xen/arch/arm/arm64/debug-imx-lpuart.inc | 52 +++++++++++++++++++++++++
  2 files changed, 66 insertions(+)
  create mode 100644 xen/arch/arm/arm64/debug-imx-lpuart.inc

diff --git a/xen/arch/arm/Kconfig.debug b/xen/arch/arm/Kconfig.debug
index 35ccd13273..842d768280 100644
--- a/xen/arch/arm/Kconfig.debug
+++ b/xen/arch/arm/Kconfig.debug
@@ -58,6 +58,16 @@ choice
                        This option is preferred over the platform specific
                        options; the platform specific options are deprecated
                        and will soon be removed.
+       config EARLY_UART_CHOICE_IMX_LPUART
+               select EARLY_UART_IMX_LPUART
+               depends on ARM_64
+               bool "Early printk via i.MX LPUART"
+               help
+                       Say Y here if you wish the early printk to direct their
+                       output to a i.MX LPUART. You can use this option to
+                       provide the parameters for the i.MX LPUART rather than
+                       selecting one of the platform specific options below if
+                       you know the parameters for the port.
        config EARLY_UART_CHOICE_MESON
                select EARLY_UART_MESON
                depends on ARM_64
@@ -186,6 +196,9 @@ config EARLY_UART_CADENCE
  config EARLY_UART_EXYNOS4210
        select EARLY_PRINTK
        bool
+config EARLY_UART_IMX_LPUART
+       select EARLY_PRINTK
+       bool
  config EARLY_UART_MESON
        select EARLY_PRINTK
        bool
@@ -283,6 +296,7 @@ config EARLY_PRINTK_INC
        default "debug-8250.inc" if EARLY_UART_8250
        default "debug-cadence.inc" if EARLY_UART_CADENCE
        default "debug-exynos4210.inc" if EARLY_UART_EXYNOS4210
+       default "debug-imx-lpuart.inc" if EARLY_UART_IMX_LPUART
        default "debug-meson.inc" if EARLY_UART_MESON
        default "debug-mvebu.inc" if EARLY_UART_MVEBU
        default "debug-pl011.inc" if EARLY_UART_PL011
diff --git a/xen/arch/arm/arm64/debug-imx-lpuart.inc 
b/xen/arch/arm/arm64/debug-imx-lpuart.inc
new file mode 100644
index 0000000000..f68252da86
--- /dev/null
+++ b/xen/arch/arm/arm64/debug-imx-lpuart.inc
@@ -0,0 +1,52 @@
+/*
+ * xen/arch/arm/arm64/debug-imx-lpuart.inc
+ *
+ * i.MX8QM specific debug code
+ *
+ * Peng Fan <peng.fan@xxxxxxx>
+ * Copyright 2022 NXP
+ *
+ * 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; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * 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.
+ */
+
+#include <asm/imx-lpuart.h>
+
+.macro early_uart_init wb wc wd
+/* Already initialized in bootloader */
+.endm
+
FWICS, early_uart_init call is protected with CONFIG_EARLY_UART_INIT that is set
only for PL011 UART. So I think there is no need to implement this empty macro,
unless we want to keep the same macros across the files no matter whether in 
use or not.
I think you need to ask Julien.

The call to early_uart_init is indeed protected by #ifdef CONFIG_EARLY_UART_INIT. The goal was to avoid having all debug-*.inc to implement dummy helper.

So I would prefer if early_uart_init is not implemented for debug-imx-lpuart.inc.

Cheers,

--
Julien Grall



 


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