On Fri, 7 May 2021 13:45:57 +0200
Ahmad Fatoum <a.fatoum@xxxxxxxxxxxxxx> wrote:
> Hi,
>
> On 07.05.21 00:08, Antony Pavlov wrote:
> > Signed-off-by: Antony Pavlov <antonynpavlov@xxxxxxxxx>
> > ---
> > drivers/serial/Makefile | 1 +
> > drivers/serial/serial_litex.c | 96 +++++++++++++++++++++++++++++++++++
> > 2 files changed, 97 insertions(+)
> >
> > diff --git a/drivers/serial/Makefile b/drivers/serial/Makefile
> > index 5120b17376..45055371ea 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_SOC_LITEX) += serial_litex.o
> > diff --git a/drivers/serial/serial_litex.c b/drivers/serial/serial_litex.c
> > new file mode 100644
> > index 0000000000..8562a45ecc
> > --- /dev/null
> > +++ b/drivers/serial/serial_litex.c
> > @@ -0,0 +1,96 @@
> > +// SPDX-License-Identifier: GPL-2.0
> > +/*
> > + * Copyright (C) 2019 Antony Pavlov <antonynpavlov@xxxxxxxxx>
> > + *
> > + */
> > +
> > +#include <common.h>
> > +#include <init.h>
> > +#include <io.h>
> > +
> > +#define UART_RXTX 0x00
> > +#define UART_TXFULL 0x04
> > +#define UART_RXEMPTY 0x08
> > +#define UART_EV_PENDING 0x10
> > +#define UART_EV_RX (1 << 1)
> > +
> > +static inline uint32_t litex_serial_readb(struct console_device *cdev,
> > + uint32_t offset)
> > +{
> > + void __iomem *base = cdev->dev->priv;
> > +
> > + return readb(base + offset);
> > +}
> > +
> > +static inline void litex_serial_writeb(struct console_device *cdev,
> > + uint32_t value, uint32_t offset)
> > +{
> > + void __iomem *base = cdev->dev->priv;
> > +
> > + writeb(value, base + offset);
> > +}
> > +
> > +static void litex_serial_putc(struct console_device *cdev, char c)
> > +{
> > + while (litex_serial_readb(cdev, UART_TXFULL))
> > + ;
> > +
> > + litex_serial_writeb(cdev, c, UART_RXTX);
> > +}
> > +
> > +static int litex_serial_getc(struct console_device *cdev)
> > +{
> > + int c;
> > +
> > + while (litex_serial_readb(cdev, UART_RXEMPTY))
> > + ;
> > +
> > + c = litex_serial_readb(cdev, UART_RXTX);
> > +
> > + /* refresh UART_RXEMPTY by writing UART_EV_RX to UART_EV_PENDING */
> > + litex_serial_writeb(cdev, UART_EV_RX, UART_EV_PENDING);
> > +
> > + return c;
> > +}
> > +
> > +static int litex_serial_tstc(struct console_device *cdev)
> > +{
> > + return !litex_serial_readb(cdev, UART_RXEMPTY);
> > +}
> > +
> > +static int litex_serial_probe(struct device_d *dev)
> > +{
> > + struct resource *iores;
> > + struct console_device *cdev;
> > +
> > + cdev = xzalloc(sizeof(struct console_device));
> > + iores = dev_request_mem_resource(dev, 0);
> > + if (IS_ERR(iores))
> > + return PTR_ERR(iores);
> > +
> > + dev->priv = IOMEM(iores->start);
> > + cdev->dev = dev;
> > + cdev->tstc = &litex_serial_tstc;
> > + cdev->putc = &litex_serial_putc;
> > + cdev->getc = &litex_serial_getc;
> > + cdev->setbrg = NULL;
>
> Does the IP only output a fixed baudrate/configuration?
Yes, this IP works at fixed baudrate.
Baudrate is selected during FPGA bitstream compilation,
e.g. see https://github.com/litex-hub/linux-on-litex-vexriscv/commit/0b133cc3
At the moment there is a problem with this fixed speed port: loady command does not work.
> > +
> > + console_register(cdev);
> > +
> > + return 0;
> > +}
> > +
> > +static __maybe_unused struct of_device_id litex_serial_dt_ids[] = {
> > + {
> > + .compatible = "litex,uart",
> > + }, {
> > + /* sentinel */
> > + }
> > +};
> > +
> > +static struct driver_d litex_serial_driver = {
> > + .name = "litex-uart",
> > + .probe = litex_serial_probe,
> > + .of_compatible = DRV_OF_COMPAT(litex_serial_dt_ids),
> > +};
> > +console_platform_driver(litex_serial_driver);
> >
>
> --
> Pengutronix e.K. | |
> Steuerwalder Str. 21 | http://www.pengutronix.de/ |
> 31137 Hildesheim, Germany | Phone: +49-5121-206917-0 |
> Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 |
--
Best regards,
Antony Pavlov
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