[PATCH v2 05/11] serial: add litex UART driver

[Ahmad Fatoum]

Hi,

On 07.05.21 00:08, Antony Pavlov wrote:
> Signed-off-by: Antony Pavlov <antonynpavlov at gmail.com>
> ---
>  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 at gmail.com>
> + *
> + */
> +
> +#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?

> +
> +	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);
> 

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