Re: [U-Boot] [PATCH 4/4] armv8/ls1043aqds: Initizlize NS16550 if enalbed LPUART

[Wenbin Song]

Hi: Bin,
      Because we use the ns16550  as the early console when booting  kernel , 
and the earlycon driver on kernel  cannot initialize port->uartclk rightly, So 
if we want to use it, we must initialize ns16550 on uboot, and use the bootargs 
 as follow :
      "console=ttyS0,115200 root=/dev/ram0  earlycon=uart8250,0x21c0500 "  

int __init early_serial8250_setup(struct earlycon_device *device,
                                         const char *options)
{
        if (!(device->port.membase || device->port.iobase))
                return -ENODEV;

        if (!device->baud) {
                struct uart_port *port = &device->port;
                unsigned int ier;

                /* assume the device was initialized, only mask interrupts */
                ier = serial8250_early_in(port, UART_IER);
                serial8250_early_out(port, UART_IER, ier & UART_IER_UUE);
        } else
                init_port(device);

        device->con->write = early_serial8250_write;
        return 0;
}

Regards

Wenbin Song


-----Original Message-----
From: Bin Meng [mailto:bmeng...@gmail.com] 
Sent: Tuesday, January 19, 2016 4:08 PM
To: Wenbin Song <wenbin.s...@nxp.com>
Cc: York Sun <york...@freescale.com>; Mingkai Hu <mingkai...@nxp.com>; Qianyu 
Gong <qianyu.g...@nxp.com>; Shaohui Xie <shaohui....@nxp.com>; U-Boot Mailing 
List <u-boot@lists.denx.de>; Wenbin Song <wenbin.s...@freescale.com>
Subject: Re: [U-Boot] [PATCH 4/4] armv8/ls1043aqds: Initizlize NS16550 if 
enalbed LPUART

Hi Wenbin,

On Tue, Jan 19, 2016 at 2:48 PM, Wenbin Song <wenbin.s...@nxp.com> wrote:
> From: Wenbin Song <wenbin.s...@freescale.com>
>
> Need to initialize ns16550 to support earlycon on kernel.
>
> Signed-off-by: Wenbin Song <wenbin.s...@freescale.com>
> Signed-off-by: Mingkai Hu <mingkai...@freescale.com>
> ---
>  board/freescale/ls1043aqds/ls1043aqds.c | 12 ++++++++++++
>  configs/ls1043aqds_lpuart_defconfig     |  1 +
>  include/configs/ls1043aqds.h            |  3 ++-
>  3 files changed, 15 insertions(+), 1 deletion(-)
>
> diff --git a/board/freescale/ls1043aqds/ls1043aqds.c 
> b/board/freescale/ls1043aqds/ls1043aqds.c
> index 1da3fe1..fcbd95c 100644
> --- a/board/freescale/ls1043aqds/ls1043aqds.c
> +++ b/board/freescale/ls1043aqds/ls1043aqds.c
> @@ -21,6 +21,7 @@
>  #include <fsl_esdhc.h>
>  #include <fsl_ifc.h>
>  #include <spl.h>
> +#include <ns16550.h>
>
>  #include "../common/qixis.h"
>  #include "ls1043aqds_qixis.h"
> @@ -219,6 +220,17 @@ void board_retimer_init(void)
>         i2c_write(I2C_RETIMER_ADDR, 0x64, 1, &reg, 1);  }
>
> +int board_early_init_r(void)
> +{
> +#ifdef CONFIG_LPUART
> +    /* Initialize ns16500 for earlycon on kernel.*/
> +       NS16550_init((NS16550_t)CONFIG_SYS_NS16550_COM1,
> +                    DIV_ROUND_CLOSEST(CONFIG_SYS_NS16550_CLK,
> +                                      16 * CONFIG_BAUDRATE)); #endif

This change does not make a lot sense to me. Since U-Boot is using LPUART as 
its system console, why do you want to load a kernel that uses the NS16550 as 
the system console? IMHO we should ask kernel to use LPUART as well, IOW keep 
in sync with the underlying bootloader.

> +       return 0;
> +}
> +
>  int board_early_init_f(void)
>  {
>  #ifdef CONFIG_LPUART
> diff --git a/configs/ls1043aqds_lpuart_defconfig 
> b/configs/ls1043aqds_lpuart_defconfig
> index ca06abe..26f7b36 100644
> --- a/configs/ls1043aqds_lpuart_defconfig
> +++ b/configs/ls1043aqds_lpuart_defconfig
> @@ -1,6 +1,7 @@
>  CONFIG_SYS_EXTRA_OPTIONS="SYS_FSL_DDR4,LPUART"
>  CONFIG_ARM=y
>  CONFIG_TARGET_LS1043AQDS=y
> +CONFIG_SYS_NS16550=y
>  CONFIG_DEFAULT_DEVICE_TREE="fsl-ls1043a-qds"
>  CONFIG_OF_CONTROL=y
>  CONFIG_DM=y
> diff --git a/include/configs/ls1043aqds.h 
> b/include/configs/ls1043aqds.h index 88f4bc0..d66d8f9 100644
> --- a/include/configs/ls1043aqds.h
> +++ b/include/configs/ls1043aqds.h
> @@ -30,6 +30,8 @@ unsigned long get_board_ddr_clk(void);
>
>  #define CONFIG_LAYERSCAPE_NS_ACCESS
>
> +#define CONFIG_BOARD_EARLY_INIT_R
> +
>  #define CONFIG_DIMM_SLOTS_PER_CTLR     1
>  /* Physical Memory Map */
>  #define CONFIG_CHIP_SELECTS_PER_CTRL   4
> @@ -96,7 +98,6 @@ unsigned long get_board_ddr_clk(void);  #define 
> CONFIG_LPUART_32B_REG  #undef CONFIG_CONS_INDEX  #undef 
> CONFIG_SYS_NS16550_SERIAL -#undef CONFIG_SYS_NS16550_CLK  #endif
>
>  /* SATA */
> --

Regards,
Bin
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