Re: Fwd: [PATCH] serial: implement riscv SBI console support

[Marcelo Politzer <marcelo.politzer@cartesi.io>]

Thank you for taking the time to review,

I've sent a v2 with your suggestions incorporated.

best,
Marcelo

On Sat, Sep 25, 2021 at 3:32 PM Antony Pavlov <antonynpavlov@gmail.com> wrote:
>
> On Fri, 24 Sep 2021 10:13:38 -0300
> Marcelo Politzer <marcelo.politzer@cartesi.io> wrote:
>
> Hi, Marcelo!
>
>
> > Implement a console over legacy SBI (version 0.1.0). There is a tiny ringbuffer
> > to simplify checking for presence and reading characters as separate steps.
> >
> > Signed-off-by: Marcelo Politzer <marcelo.politzer@cartesi.io>
> > ---
> >  arch/riscv/cpu/core.c       | 13 ++++++++
> >  arch/riscv/lib/sbi.c        | 11 +++++++
> >  drivers/serial/Kconfig      |  8 +++++
> >  drivers/serial/Makefile     |  1 +
> >  drivers/serial/serial_sbi.c | 60 +++++++++++++++++++++++++++++++++++++
> >  5 files changed, 93 insertions(+)
> >  create mode 100644 drivers/serial/serial_sbi.c
> >
> > diff --git a/arch/riscv/cpu/core.c b/arch/riscv/cpu/core.c
> > index 80730c05b..9226037f3 100644
> > --- a/arch/riscv/cpu/core.c
> > +++ b/arch/riscv/cpu/core.c
> > @@ -24,6 +24,7 @@
> >  #include <magicvar.h>
> >  #include <asm/system.h>
> >  #include <io.h>
> > +#include <asm/sbi.h>
>
> There is no need to include <asm/sbi.h> here.
>
> >
> >  static int riscv_request_stack(void)
> >  {
> > @@ -33,6 +34,7 @@ static int riscv_request_stack(void)
> >  coredevice_initcall(riscv_request_stack);
> >
> >  static struct device_d timer_dev;
> > +static struct device_d serial_sbi_dev;
> >
> >  static s64 hartid;
> >
> > @@ -75,6 +77,17 @@ static int riscv_probe(struct device_d *parent)
> >                         return ret;
> >         }
> >
> > +       if (IS_ENABLED(CONFIG_SERIAL_SBI) && !serial_sbi_dev.parent) {
> > +               serial_sbi_dev.id = DEVICE_ID_SINGLE;
> > +               serial_sbi_dev.device_node = 0;
> > +               serial_sbi_dev.parent = parent;
> > +               dev_set_name(&serial_sbi_dev, "riscv-serial-sbi");
> > +
> > +               ret = platform_device_register(&serial_sbi_dev);
> > +               if (ret)
> > +                       return ret;
> > +       }
> > +
>
> Please, use tabs for indentation!
>
>
> >         hartid = riscv_hartid();
> >         if (hartid >= 0)
> >                 globalvar_add_simple_uint64("hartid", &hartid, "%llu");
> > diff --git a/arch/riscv/lib/sbi.c b/arch/riscv/lib/sbi.c
> > index 45a04fb82..209069c98 100644
> > --- a/arch/riscv/lib/sbi.c
> > +++ b/arch/riscv/lib/sbi.c
> > @@ -64,3 +64,14 @@ static int sbi_init(void)
> >
> >  }
> >  core_initcall(sbi_init);
> > +
> > +
>
> No extra emptyline here.
>
> > +void sbi_console_putchar(int ch)
> > +{
> > +       sbi_ecall(SBI_EXT_0_1_CONSOLE_PUTCHAR, 0, ch, 0, 0, 0, 0, 0);
> > +}
> > +
> > +int sbi_console_getchar(void)
> > +{
> > +       return sbi_ecall(SBI_EXT_0_1_CONSOLE_GETCHAR, 0, 0, 0, 0, 0,
> > 0, 0).error;
> > +}
> > diff --git a/drivers/serial/Kconfig b/drivers/serial/Kconfig
> > index b9750d177..5e30ea388 100644
> > --- a/drivers/serial/Kconfig
> > +++ b/drivers/serial/Kconfig
> > @@ -173,4 +173,12 @@ config SERIAL_SIFIVE
> >           contains a SiFive UART IP block.  This type of UART is present on
> >           SiFive FU540 SoCs, among others.
> >
> > +config SERIAL_SBI
> > +       tristate "RISCV Serial support over SBI's HTIF"
> > +       depends on OFDEVICE
> > +       depends on RISCV_SBI
> > +       help
> > +         Select this option if you are building barebox for a RISCV platform
> > +         that implements a serial over SBI.
> > +
> >  endmenu
> > diff --git a/drivers/serial/Makefile b/drivers/serial/Makefile
> > index 5120b1737..b1de436ed 100644
> > --- a/drivers/serial/Makefile
> > +++ b/drivers/serial/Makefile
> > @@ -24,3 +24,4 @@ obj-$(CONFIG_DRIVER_SERIAL_DIGIC)             +=
> > serial_digic.o
> >  obj-$(CONFIG_DRIVER_SERIAL_LPUART)             += serial_lpuart.o
> >  obj-$(CONFIG_VIRTIO_CONSOLE)                   += virtio_console.o
> >  obj-$(CONFIG_SERIAL_SIFIVE)                    += serial_sifive.o
> > +obj-$(CONFIG_SERIAL_SBI)                       += serial_sbi.o
> > diff --git a/drivers/serial/serial_sbi.c b/drivers/serial/serial_sbi.c
> > new file mode 100644
> > index 000000000..7217ce9cc
> > --- /dev/null
> > +++ b/drivers/serial/serial_sbi.c
> > @@ -0,0 +1,60 @@
> > +// SPDX-License-Identifier: GPL-2.0+
> > +/*
> > + * Copyright (C) 2021 Marcelo Politzer <marcelo.politzer@cartesi.io>
> > + */
> > +
> > +#include <common.h>
> > +#include <driver.h>
> > +#include <malloc.h>
> > +#include <io.h>
> > +#include <of.h>
>
> Please drop <io.h> and <of.h> inclusion here. These header files are unused.
>
> > +#include <asm/sbi.h>
> > +
> > +struct sbi_serial_priv {
> > +       struct console_device cdev;
> > +       uint8_t b[2], head, tail;
> > +};
> > +
> > +static int sbi_serial_getc(struct console_device *cdev)
> > +{
> > +       struct sbi_serial_priv *priv = cdev->dev->priv;
> > +       if (priv->head == priv->tail)
> > +               return -1;
> > +       return priv->b[priv->head++ & 0x1];
> > +}
> > +
> > +static void sbi_serial_putc(struct console_device *cdev, const char ch)
> > +{
> > +       sbi_console_putchar(ch);
> > +}
> > +
> > +static int sbi_serial_tstc(struct console_device *cdev)
> > +{
> > +       struct sbi_serial_priv *priv = cdev->dev->priv;
> > +       int c = sbi_console_getchar();
> > +
> > +       if (c != -1)
> > +               priv->b[priv->tail++ & 0x1] = c;
> > +       return priv->head != priv->tail;
> > +}
> > +
> > +static int sbi_serial_probe(struct device_d *dev)
> > +{
> > +       struct sbi_serial_priv *priv;
> > +
> > +       priv = dev->priv = xzalloc(sizeof(*priv));
> > +       priv->cdev.dev    = dev;
> > +       priv->cdev.putc   = sbi_serial_putc;
> > +       priv->cdev.getc   = sbi_serial_getc;
> > +       priv->cdev.tstc   = sbi_serial_tstc;
> > +       priv->cdev.flush  = 0;
> > +       priv->cdev.setbrg = 0;
> > +
> > +       return console_register(&priv->cdev);
> > +}
> > +
> > +static struct driver_d serial_sbi_driver = {
> > +       .name   = "riscv-serial-sbi",
> > +       .probe  = sbi_serial_probe,
> > +};
> > +postcore_platform_driver(serial_sbi_driver);
> > --
> > 2.32.0
> >
> > _______________________________________________
> > barebox mailing list
> > barebox@lists.infradead.org
> > http://lists.infradead.org/mailman/listinfo/barebox
>
>
> --
> Best regards,
>   Antony Pavlov

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