[U-Boot] [PATCH 20/48] efi: Add a serial driver

[Bin Meng]

Hi Simon,

On Wed, Jul 22, 2015 at 11:49 PM, Simon Glass <sjg at chromium.org> wrote:
> Add a serial driver which makes use of EFI's console in/out service.
>
> Signed-off-by: Simon Glass <sjg at chromium.org>
> ---
>
>  drivers/serial/Kconfig      |   8 +++
>  drivers/serial/Makefile     |   1 +
>  drivers/serial/serial_efi.c | 149 ++++++++++++++++++++++++++++++++++++++++++++
>  3 files changed, 158 insertions(+)
>  create mode 100644 drivers/serial/serial_efi.c
>
> diff --git a/drivers/serial/Kconfig b/drivers/serial/Kconfig
> index 4829284..f874837 100644
> --- a/drivers/serial/Kconfig
> +++ b/drivers/serial/Kconfig
> @@ -44,6 +44,14 @@ config DEBUG_UART_NS16550
>           will need to provide parameters to make this work. The driver will
>           be available until the real driver model serial is running.
>
> +config DEBUG_UART_EFI

This driver looks like a normal serial driver, except one debug uart
api _debug_uart_putc(). Also it can not only support UART, but also
support any console input/output devices that EFI supports. Should we
rename it to: EFI_CONSOLE?

> +       bool "EFI"

depends on EFI_APP?

> +       help
> +         Select this to enable a debug UART which calls back to EFI to output
> +         to the console. This can be useful for early debugging of U-Boot
> +         when running on top of EFI (Extensive Firmware Interface). This is
> +         a type of BIOS used by PCs.
> +
>  endchoice
>
>  config DEBUG_UART_BASE
> diff --git a/drivers/serial/Makefile b/drivers/serial/Makefile
> index d183eed..92c3808 100644
> --- a/drivers/serial/Makefile
> +++ b/drivers/serial/Makefile
> @@ -21,6 +21,7 @@ obj-$(CONFIG_ALTERA_JTAG_UART) += altera_jtag_uart.o
>  obj-$(CONFIG_ARM_DCC) += arm_dcc.o
>  obj-$(CONFIG_ATMEL_USART) += atmel_usart.o
>  obj-$(CONFIG_DW_SERIAL) += serial_dw.o
> +obj-$(CONFIG_ARCH_EFI) += serial_efi.o
>  obj-$(CONFIG_LPC32XX_HSUART) += lpc32xx_hsuart.o
>  obj-$(CONFIG_MCFUART) += mcfuart.o
>  obj-$(CONFIG_OPENCORES_YANU) += opencores_yanu.o
> diff --git a/drivers/serial/serial_efi.c b/drivers/serial/serial_efi.c
> new file mode 100644
> index 0000000..15e541b
> --- /dev/null
> +++ b/drivers/serial/serial_efi.c
> @@ -0,0 +1,149 @@
> +/*
> + * Copyright (c) 2015 Google, Inc
> + * Written by Simon Glass <sjg at chromium.org>
> + *
> + * SPDX-License-Identifier:    GPL-2.0+
> + */
> +
> +#include <common.h>
> +#include <debug_uart.h>
> +#include <dm.h>
> +#include <efi.h>
> +#include <efi_api.h>
> +#include <errno.h>
> +#include <fdtdec.h>
> +#include <linux/compiler.h>
> +#include <asm/io.h>
> +#include <serial.h>
> +
> +DECLARE_GLOBAL_DATA_PTR;

Is this needed? I don't see gd is referenced.

> +
> +/* Information about the efi console */
> +struct serial_efi_priv {
> +       struct efi_simple_input_interface *con_in;
> +       struct efi_simple_text_output_protocol *con_out;
> +       struct efi_input_key key;
> +       bool have_key;
> +};
> +
> +int serial_efi_setbrg(struct udevice *dev, int baudrate)
> +{
> +       return 0;
> +}
> +
> +static int serial_efi_get_key(struct serial_efi_priv *priv)
> +{
> +       int ret;
> +
> +       if (priv->have_key)
> +               return 0;
> +       ret = priv->con_in->read_key_stroke(priv->con_in, &priv->key);
> +       if (ret == EFI_NOT_READY)
> +               return -EAGAIN;
> +       else if (ret != EFI_SUCCESS)
> +               return -EIO;
> +
> +       priv->have_key = true;
> +
> +       return 0;
> +}
> +
> +static int serial_efi_getc(struct udevice *dev)
> +{
> +       struct serial_efi_priv *priv = dev_get_priv(dev);
> +       int ret, ch;
> +
> +       ret = serial_efi_get_key(priv);
> +       if (ret)
> +               return ret;
> +
> +       priv->have_key = false;
> +       ch = priv->key.unicode_char;

What is 8 here? Can we add a comment here?

> +       if (!ch && priv->key.scan_code == 8)
> +               ch = 8;
> +       debug(" [%x %x %x] ", ch, priv->key.unicode_char, priv->key.scan_code);
> +
> +       return ch;
> +}
> +
> +static int serial_efi_putc(struct udevice *dev, const char ch)
> +{
> +       struct serial_efi_priv *priv = dev_get_priv(dev);
> +       uint16_t ucode[2];
> +       int ret;
> +
> +       ucode[0] = ch;
> +       ucode[1] = '\0';
> +       ret = priv->con_out->output_string(priv->con_out, ucode);
> +       if (ret)
> +               return -EIO;
> +
> +       return 0;
> +}
> +
> +static int serial_efi_pending(struct udevice *dev, bool input)
> +{
> +       struct serial_efi_priv *priv = dev_get_priv(dev);
> +       int ret;
> +
> +       /* We assume that EFI will stall if its output buffer fills up */
> +       if (!input)
> +               return 0;
> +
> +       ret = serial_efi_get_key(priv);
> +       if (ret == -EAGAIN)
> +               return 0;
> +       else if (ret)
> +               return ret;
> +
> +       return 1;
> +}
> +
> +void debug_uart_init(void)
> +{
> +}

Can we add come comments here to mention nothing needs to be done here for EFI?

> +
> +static inline void _debug_uart_putc(int ch)
> +{
> +       struct efi_system_table *sys_table = efi_get_sys_table();
> +       uint16_t ucode[2];
> +
> +       ucode[0] = ch;
> +       ucode[1] = '\0';
> +       sys_table->con_out->output_string(sys_table->con_out, ucode);
> +}
> +
> +DEBUG_UART_FUNCS
> +
> +static int serial_efi_probe(struct udevice *dev)
> +{
> +       struct efi_system_table *table = efi_get_sys_table();
> +       struct serial_efi_priv *priv = dev_get_priv(dev);
> +
> +       priv->con_in = table->con_in;
> +       priv->con_out = table->con_out;
> +
> +       return 0;
> +}
> +
> +static const struct dm_serial_ops serial_efi_ops = {
> +       .putc = serial_efi_putc,
> +       .getc = serial_efi_getc,
> +       .pending = serial_efi_pending,
> +       .setbrg = serial_efi_setbrg,
> +};
> +
> +static const struct udevice_id serial_efi_ids[] = {
> +       { .compatible = "efi,uart" },
> +       { }
> +};
> +
> +U_BOOT_DRIVER(serial_s5p) = {

Should be serial_efi.

> +       .name   = "serial_s5p",

The same here.

> +       .id     = UCLASS_SERIAL,
> +       .of_match = serial_efi_ids,
> +       .priv_auto_alloc_size = sizeof(struct serial_efi_priv),
> +       .probe = serial_efi_probe,
> +       .ops    = &serial_efi_ops,
> +       .flags = DM_FLAG_PRE_RELOC,
> +};
> --

Regards,
Bin