Re: [Xen-devel] [PATCH v2 2/3] xen/arm: Add MESON UART driver for Amlogic Meson SoCs

[André Przywara <andre.przywara@xxxxxxx>]

On 21/03/2019 10:25, Amit Singh Tomar wrote:
> This patch adds driver for UART controller present on Amlogic Meson
> SoCs and it has been tested on Nanopi K2 board based on S905 SoC.
> 
> Controller registers defination is taken from Linux 4.20.
> https://github.com/torvalds/linux/blob/v4.20-rc1/drivers/tty/serial/meson_uart.c
> 
> Signed-off-by: Amit Singh Tomar <amittomer25@xxxxxxxxx>

Thanks for the changes!

Reviewed-by: Andre Przywara <andre.przywara@xxxxxxx>

Cheers,
Andre.

> ---
> Changes since v1:
> 
>         * Removed clrsetbits macro.
>         * Fixed coding style issue.
>         * Updated MAINTAINERS file.
> 
> Changes since RFC:
> 
>         * Removed S905 reference as other Amlogic SoCs
>           have this uart controller.
>         * Replaced meson_s905_read/write helper
>           with clrsetbit and friends helper.
>         * Followed proper UART reset sequence.
>         * List all UART compatible strings same as Linux
>           driver.
> ---
>  xen/drivers/char/Kconfig      |   8 ++
>  xen/drivers/char/Makefile     |   1 +
>  xen/drivers/char/meson-uart.c | 276 
> ++++++++++++++++++++++++++++++++++++++++++
>  3 files changed, 285 insertions(+)
>  create mode 100644 xen/drivers/char/meson-uart.c
> 
> diff --git a/xen/drivers/char/Kconfig b/xen/drivers/char/Kconfig
> index b1f07f8..b572305 100644
> --- a/xen/drivers/char/Kconfig
> +++ b/xen/drivers/char/Kconfig
> @@ -20,6 +20,14 @@ config HAS_MVEBU
>         This selects the Marvell MVEBU UART. If you have a ARMADA 3700
>         based board, say Y.
>  
> +config HAS_MESON
> +     bool "Amlogic MESON UART driver"
> +     default y
> +     depends on ARM_64
> +     help
> +       This selects the Amlogic MESON UART. If you have a Amlogic based
> +       board, say Y.
> +
>  config HAS_PL011
>       bool "ARM PL011 UART driver"
>       default y
> diff --git a/xen/drivers/char/Makefile b/xen/drivers/char/Makefile
> index b68c330..7c646d7 100644
> --- a/xen/drivers/char/Makefile
> +++ b/xen/drivers/char/Makefile
> @@ -3,6 +3,7 @@ obj-$(CONFIG_HAS_NS16550) += ns16550.o
>  obj-$(CONFIG_HAS_CADENCE_UART) += cadence-uart.o
>  obj-$(CONFIG_HAS_PL011) += pl011.o
>  obj-$(CONFIG_HAS_EXYNOS4210) += exynos4210-uart.o
> +obj-$(CONFIG_HAS_MESON) += meson-uart.o
>  obj-$(CONFIG_HAS_MVEBU) += mvebu-uart.o
>  obj-$(CONFIG_HAS_OMAP) += omap-uart.o
>  obj-$(CONFIG_HAS_SCIF) += scif-uart.o
> diff --git a/xen/drivers/char/meson-uart.c b/xen/drivers/char/meson-uart.c
> new file mode 100644
> index 0000000..c16c188
> --- /dev/null
> +++ b/xen/drivers/char/meson-uart.c
> @@ -0,0 +1,276 @@
> +/*
> + * xen/drivers/char/meson-uart.c
> + *
> + * Driver for Amlogic MESON UART
> + *
> + * Copyright (c) 2019, Amit Singh Tomar <amittomer25@xxxxxxxxx>.
> + *
> + * This program is free software; you can redistribute it and/or
> + * modify it under the terms and conditions of the GNU General Public
> + * License, version 2, as published by the Free Software Foundation.
> + *
> + * This program is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> + * General Public License for more details.
> + *
> + * You should have received a copy of the GNU General Public
> + * License along with this program; If not, see 
> <http://www.gnu.org/licenses/>.
> + */
> +
> +#include <xen/irq.h>
> +#include <xen/serial.h>
> +#include <xen/vmap.h>
> +#include <asm/io.h>
> +
> +/* Register offsets */
> +#define AML_UART_WFIFO_REG              0x00
> +#define AML_UART_RFIFO_REG              0x04
> +#define AML_UART_CONTROL_REG            0x08
> +#define AML_UART_STATUS_REG             0x0c
> +#define AML_UART_MISC_REG               0x10
> +
> +/* UART_CONTROL bits */
> +#define AML_UART_TX_RST                 BIT(22)
> +#define AML_UART_RX_RST                 BIT(23)
> +#define AML_UART_CLEAR_ERR              BIT(24)
> +#define AML_UART_RX_INT_EN              BIT(27)
> +#define AML_UART_TX_INT_EN              BIT(28)
> +
> +/* UART_STATUS bits */
> +#define AML_UART_RX_FIFO_EMPTY          BIT(20)
> +#define AML_UART_TX_FIFO_FULL           BIT(21)
> +#define AML_UART_TX_FIFO_EMPTY          BIT(22)
> +#define AML_UART_TX_CNT_MASK            GENMASK(14, 8)
> +
> +/* AML_UART_MISC bits */
> +#define AML_UART_XMIT_IRQ(c)            (((c) & 0xff) << 8)
> +#define AML_UART_RECV_IRQ(c)            ((c) & 0xff)
> +
> +#define TX_FIFO_SIZE                    64
> +
> +#define setbits(addr, set)              writel((readl(addr) | (set)), (addr))
> +#define clrbits(addr, clear)            writel((readl(addr) & ~(clear)), 
> (addr))
> +
> +static struct meson_uart {
> +    unsigned int irq;
> +    void __iomem *regs;
> +    struct irqaction irqaction;
> +    struct vuart_info vuart;
> +} meson_com;
> +
> +static void meson_uart_interrupt(int irq, void *data,
> +                                 struct cpu_user_regs *regs)
> +{
> +    struct serial_port *port = data;
> +    struct meson_uart *uart = port->uart;
> +    uint32_t st = readl(uart->regs + AML_UART_STATUS_REG);
> +
> +    if ( !(st & AML_UART_RX_FIFO_EMPTY) )
> +        serial_rx_interrupt(port, regs);
> +
> +    if ( !(st & AML_UART_TX_FIFO_FULL) )
> +        serial_tx_interrupt(port, regs);
> +}
> +
> +static void __init meson_uart_init_preirq(struct serial_port *port)
> +{
> +    struct meson_uart *uart = port->uart;
> +
> +    /* Reset UART */
> +    setbits(uart->regs + AML_UART_CONTROL_REG,
> +            (AML_UART_RX_RST | AML_UART_TX_RST | AML_UART_CLEAR_ERR));
> +
> +    clrbits(uart->regs + AML_UART_CONTROL_REG,
> +            (AML_UART_RX_RST | AML_UART_TX_RST | AML_UART_CLEAR_ERR));
> +
> +    /* Disable Rx/Tx interrupts */
> +    clrbits(uart->regs + AML_UART_CONTROL_REG,
> +               (AML_UART_RX_INT_EN | AML_UART_TX_INT_EN));
> +}
> +
> +static void __init meson_uart_init_postirq(struct serial_port *port)
> +{
> +    struct meson_uart *uart = port->uart;
> +
> +    uart->irqaction.handler = meson_uart_interrupt;
> +    uart->irqaction.name    = "meson_uart";
> +    uart->irqaction.dev_id  = port;
> +
> +    if ( setup_irq(uart->irq, 0, &uart->irqaction) != 0 )
> +    {
> +        printk("Failed to allocated Meson UART IRQ %d\n", uart->irq);
> +        return;
> +    }
> +
> +    /*
> +     * Configure Rx/Tx interrupts based on bytes in FIFO, these bits have
> +     * taken from Linux driver
> +     */
> +    writel((AML_UART_RECV_IRQ(1) | AML_UART_XMIT_IRQ(TX_FIFO_SIZE / 2)),
> +           uart->regs + AML_UART_MISC_REG);
> +
> +    /* Make sure Rx/Tx interrupts are enabled now */
> +    setbits(uart->regs + AML_UART_CONTROL_REG,
> +            (AML_UART_RX_INT_EN | AML_UART_TX_INT_EN));
> +}
> +
> +static void meson_uart_suspend(struct serial_port *port)
> +{
> +    BUG();
> +}
> +
> +static void meson_uart_resume(struct serial_port *port)
> +{
> +    BUG();
> +}
> +
> +static void meson_uart_putc(struct serial_port *port, char c)
> +{
> +    struct meson_uart *uart = port->uart;
> +
> +    writel(c, uart->regs + AML_UART_WFIFO_REG);
> +}
> +
> +static int meson_uart_getc(struct serial_port *port, char *c)
> +{
> +    struct meson_uart *uart = port->uart;
> +
> +    if ( (readl(uart->regs + AML_UART_STATUS_REG) & AML_UART_RX_FIFO_EMPTY) )
> +        return 0;
> +
> +    *c = readl(uart->regs + AML_UART_RFIFO_REG) & 0xff;
> +
> +    return 1;
> +}
> +
> +static int __init meson_irq(struct serial_port *port)
> +{
> +    struct meson_uart *uart = port->uart;
> +
> +    return uart->irq;
> +}
> +
> +static const struct vuart_info *meson_vuart_info(struct serial_port *port)
> +{
> +    struct meson_uart *uart = port->uart;
> +
> +    return &uart->vuart;
> +}
> +
> +static void meson_uart_stop_tx(struct serial_port *port)
> +{
> +    struct meson_uart *uart = port->uart;
> +
> +    clrbits(uart->regs + AML_UART_CONTROL_REG, AML_UART_TX_INT_EN);
> +}
> +
> +static void meson_uart_start_tx(struct serial_port *port)
> +{
> +    struct meson_uart *uart = port->uart;
> +
> +    setbits(uart->regs + AML_UART_CONTROL_REG, AML_UART_TX_INT_EN);
> +}
> +
> +static int meson_uart_tx_ready(struct serial_port *port)
> +{
> +    struct meson_uart *uart = port->uart;
> +    uint32_t reg;
> +
> +    reg = readl(uart->regs + AML_UART_STATUS_REG);
> +
> +    if ( reg & AML_UART_TX_FIFO_EMPTY )
> +        return TX_FIFO_SIZE;
> +    if ( reg & AML_UART_TX_FIFO_FULL )
> +        return 0;
> +
> +    return (reg & AML_UART_TX_CNT_MASK) >> 8;
> +}
> +
> +static struct uart_driver __read_mostly meson_uart_driver = {
> +    .init_preirq  = meson_uart_init_preirq,
> +    .init_postirq = meson_uart_init_postirq,
> +    .endboot      = NULL,
> +    .suspend      = meson_uart_suspend,
> +    .resume       = meson_uart_resume,
> +    .putc         = meson_uart_putc,
> +    .getc         = meson_uart_getc,
> +    .tx_ready     = meson_uart_tx_ready,
> +    .stop_tx      = meson_uart_stop_tx,
> +    .start_tx     = meson_uart_start_tx,
> +    .irq          = meson_irq,
> +    .vuart_info   = meson_vuart_info,
> +};
> +
> +static int __init meson_uart_init(struct dt_device_node *dev, const void 
> *data)
> +{
> +    const char *config = data;
> +    struct meson_uart *uart;
> +    int res;
> +    u64 addr, size;
> +
> +    if ( strcmp(config, "") )
> +        printk("WARNING: UART configuration is not supported\n");
> +
> +    uart = &meson_com;
> +
> +    res = dt_device_get_address(dev, 0, &addr, &size);
> +    if ( res )
> +    {
> +        printk("meson: Unable to retrieve the base address of the UART\n");
> +        return res;
> +    }
> +
> +    res = platform_get_irq(dev, 0);
> +    if ( res < 0 )
> +    {
> +        printk("meson: Unable to retrieve the IRQ\n");
> +        return -EINVAL;
> +    }
> +
> +    uart->irq  = res;
> +
> +    uart->regs = ioremap_nocache(addr, size);
> +    if ( !uart->regs )
> +    {
> +        printk("meson: Unable to map the UART\n");
> +        return -ENOMEM;
> +    }
> +
> +    uart->vuart.base_addr = addr;
> +    uart->vuart.size = size;
> +    uart->vuart.data_off = AML_UART_WFIFO_REG;
> +    uart->vuart.status_off = AML_UART_STATUS_REG;
> +    uart->vuart.status = AML_UART_RX_FIFO_EMPTY | AML_UART_TX_FIFO_EMPTY;
> +
> +    /* Register with generic serial driver. */
> +    serial_register_uart(SERHND_DTUART, &meson_uart_driver, uart);
> +
> +    dt_device_set_used_by(dev, DOMID_XEN);
> +
> +    return 0;
> +}
> +
> +static const struct dt_device_match meson_dt_match[] __initconst =
> +{
> +    DT_MATCH_COMPATIBLE("amlogic,meson-uart"),
> +    DT_MATCH_COMPATIBLE("amlogic,meson6-uart"),
> +    DT_MATCH_COMPATIBLE("amlogic,meson8-uart"),
> +    DT_MATCH_COMPATIBLE("amlogic,meson8b-uart"),
> +    DT_MATCH_COMPATIBLE("amlogic,meson-gx-uart"),
> +    { /* sentinel */ },
> +};
> +
> +DT_DEVICE_START(meson, "Amlogic UART", DEVICE_SERIAL)
> +    .dt_match = meson_dt_match,
> +    .init = meson_uart_init,
> +DT_DEVICE_END
> +
> +/*
> + * Local variables:
> + * mode: C
> + * c-file-style: "BSD"
> + * c-basic-offset: 4
> + * indent-tabs-mode: nil
> + * End:
> +*/
> 


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