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Baudrate and pin configuration are inherited from the bootloader; the driver only enables the transmitter/receiver and wires up the RX/TX interrupts, mirroring the existing imx-lpuart driver. The i.MX8M family's UART IP differs from the LPUART used on i.MX8QM/8QXP, so a separate driver is needed. Signed-off-by: Wig Cheng --- xen/arch/arm/include/asm/imx-uart.h | 57 +++++++ xen/drivers/char/Kconfig | 8 + xen/drivers/char/Makefile | 1 + xen/drivers/char/imx-uart.c | 226 ++++++++++++++++++++++++++++ 4 files changed, 292 insertions(+) create mode 100644 xen/arch/arm/include/asm/imx-uart.h create mode 100644 xen/drivers/char/imx-uart.c diff --git a/xen/arch/arm/include/asm/imx-uart.h b/xen/arch/arm/include/asm/imx-uart.h new file mode 100644 index 0000000000..a3892020e6 --- /dev/null +++ b/xen/arch/arm/include/asm/imx-uart.h @@ -0,0 +1,57 @@ +/* SPDX-License-Identifier: GPL-2.0-only */ +/* + * Register definitions for the classic i.MX UART IP + * ("fsl,imx6q-uart" compatible), used as the console UART on the + * i.MX8M family. + * + * Register layout taken from Linux drivers/tty/serial/imx.c. + * + * Copyright 2026 Open-EP (E-Paper) Community + */ + +#ifndef ASM_IMX_UART_H +#define ASM_IMX_UART_H + +#include + +#define URXD0 0x00 /* Receiver Register */ +#define URTX0 0x40 /* Transmitter Register */ +#define UCR1 0x80 /* Control Register 1 */ +#define UCR2 0x84 /* Control Register 2 */ +#define USR1 0x94 /* Status Register 1 */ +#define USR2 0x98 /* Status Register 2 */ +#define UTS 0xb4 /* Test Register */ + +#define URXD_RX_DATA 0xff + +#define UCR1_UARTEN BIT(0, U) /* UART enable */ +#define UCR1_ATDMAEN BIT(2, U) /* Aging DMA timer enable */ +#define UCR1_TXDMAEN BIT(3, U) /* Transmitter ready DMA enable */ +#define UCR1_TXMPTYEN BIT(6, U) /* Transmitter empty interrupt enable */ +#define UCR1_RXDMAEN BIT(8, U) /* Receiver ready DMA enable */ +#define UCR1_RRDYEN BIT(9, U) /* Receiver ready interrupt enable */ +#define UCR1_TRDYEN BIT(13, U) /* Transmitter ready interrupt enable */ + +#define UCR2_SRST BIT(0, U) /* 0 = issue software reset */ +#define UCR2_RXEN BIT(1, U) /* Receiver enable */ +#define UCR2_TXEN BIT(2, U) /* Transmitter enable */ + +#define USR1_TRDY BIT(13, U) /* Transmitter ready */ + +#define USR2_RDR BIT(0, U) /* Receive data ready */ +#define USR2_ORE BIT(1, U) /* Overrun error */ + +#define UTS_TXFULL BIT(4, U) /* TX FIFO full */ +#define UTS_RXEMPTY BIT(5, U) /* RX FIFO empty */ +#define UTS_TXEMPTY BIT(6, U) /* TX FIFO empty */ + +#endif /* ASM_IMX_UART_H */ + +/* + * Local variables: + * mode: C + * c-file-style: "BSD" + * c-basic-offset: 4 + * indent-tabs-mode: nil + * End: + */ diff --git a/xen/drivers/char/Kconfig b/xen/drivers/char/Kconfig index 8e49a52c73..f237c0220d 100644 --- a/xen/drivers/char/Kconfig +++ b/xen/drivers/char/Kconfig @@ -30,6 +30,14 @@ config HAS_IMX_LPUART help This selects the i.MX LPUART. If you have i.MX8QM based board, say Y. +config HAS_IMX_UART + bool "i.MX UART driver" + default y + depends on ARM_64 + help + This selects the classic i.MX UART. If you have an i.MX8M family + based board, say Y. + config HAS_MVEBU bool "Marvell MVEBU UART driver" default y diff --git a/xen/drivers/char/Makefile b/xen/drivers/char/Makefile index 8cbbffdca8..039f566926 100644 --- a/xen/drivers/char/Makefile +++ b/xen/drivers/char/Makefile @@ -10,6 +10,7 @@ obj-$(CONFIG_HAS_SCIF) += scif-uart.o obj-$(CONFIG_HAS_EHCI) += ehci-dbgp.o obj-$(CONFIG_XHCI) += xhci-dbc.o obj-$(CONFIG_HAS_IMX_LPUART) += imx-lpuart.o +obj-$(CONFIG_HAS_IMX_UART) += imx-uart.o obj-$(CONFIG_HAS_LINFLEX) += linflex-uart.o obj-$(CONFIG_GENERIC_UART_INIT) += uart-init.o obj-y += serial.o diff --git a/xen/drivers/char/imx-uart.c b/xen/drivers/char/imx-uart.c new file mode 100644 index 0000000000..fd34b0cd11 --- /dev/null +++ b/xen/drivers/char/imx-uart.c @@ -0,0 +1,226 @@ +/* SPDX-License-Identifier: GPL-2.0-only */ +/* + * Driver for the classic i.MX UART IP ("fsl,imx6q-uart"), used as the + * console UART on the i.MX8M family (e.g. i.MX8MP). + * + * Baudrate and pin configuration are inherited from the bootloader. + * + * Copyright 2026 Open-EP (E-Paper) Community + */ + +#include +#include +#include +#include +#include +#include +#include +#include + +#define imx_uart_read(uart, off) readl((uart)->regs + (off)) +#define imx_uart_write(uart, off, val) writel((val), (uart)->regs + (off)) + +static struct imx_uart { + uint32_t irq; + char __iomem *regs; + struct irqaction irqaction; + struct vuart_info vuart; +} imx8m_com; + +static void imx_uart_interrupt(int irq, void *data) +{ + struct serial_port *port = data; + struct imx_uart *uart = port->uart; + + if ( imx_uart_read(uart, USR2) & USR2_RDR ) + serial_rx_interrupt(port); + + if ( imx_uart_read(uart, USR1) & USR1_TRDY ) + serial_tx_interrupt(port); +} + +static void __init imx_uart_init_preirq(struct serial_port *port) +{ + struct imx_uart *uart = port->uart; + uint32_t ucr1, ucr2; + + /* + * Reuse the bootloader settings; only enable the UART and both + * directions. The console uses UCR1 interrupts (RRDYEN/TRDYEN) + * exclusively, so just clear UCR1's interrupt and DMA enables. + */ + ucr1 = imx_uart_read(uart, UCR1); + ucr1 &= ~(UCR1_RRDYEN | UCR1_TRDYEN | UCR1_TXMPTYEN | UCR1_RXDMAEN | + UCR1_TXDMAEN | UCR1_ATDMAEN); + ucr1 |= UCR1_UARTEN; + imx_uart_write(uart, UCR1, ucr1); + + ucr2 = imx_uart_read(uart, UCR2); + ucr2 |= UCR2_SRST | UCR2_RXEN | UCR2_TXEN; + imx_uart_write(uart, UCR2, ucr2); +} + +static void __init imx_uart_init_postirq(struct serial_port *port) +{ + struct imx_uart *uart = port->uart; + uint32_t ucr1; + + uart->irqaction.handler = imx_uart_interrupt; + uart->irqaction.name = "imx_uart"; + uart->irqaction.dev_id = port; + + if ( setup_irq(uart->irq, 0, &uart->irqaction) != 0 ) + { + dprintk(XENLOG_ERR, "Failed to allocate imx_uart IRQ %d\n", uart->irq); + return; + } + + /* Enable the receiver ready interrupt */ + ucr1 = imx_uart_read(uart, UCR1); + ucr1 |= UCR1_RRDYEN; + imx_uart_write(uart, UCR1, ucr1); +} + +static int imx_uart_tx_ready(struct serial_port *port) +{ + struct imx_uart *uart = port->uart; + + return !(imx_uart_read(uart, UTS) & UTS_TXFULL); +} + +static void imx_uart_putc(struct serial_port *port, char c) +{ + struct imx_uart *uart = port->uart; + + while ( imx_uart_read(uart, UTS) & UTS_TXFULL ) + cpu_relax(); + + imx_uart_write(uart, URTX0, c); +} + +static int imx_uart_getc(struct serial_port *port, char *pc) +{ + struct imx_uart *uart = port->uart; + + if ( !(imx_uart_read(uart, USR2) & USR2_RDR) ) + return 0; + + *pc = imx_uart_read(uart, URXD0) & URXD_RX_DATA; + + if ( imx_uart_read(uart, USR2) & USR2_ORE ) + imx_uart_write(uart, USR2, USR2_ORE); + + return 1; +} + +static int __init imx_uart_irq(struct serial_port *port) +{ + struct imx_uart *uart = port->uart; + + return ((uart->irq > 0) ? uart->irq : -1); +} + +static const struct vuart_info *imx_uart_vuart_info(struct serial_port *port) +{ + struct imx_uart *uart = port->uart; + + return &uart->vuart; +} + +static void imx_uart_start_tx(struct serial_port *port) +{ + struct imx_uart *uart = port->uart; + uint32_t ucr1; + + ucr1 = imx_uart_read(uart, UCR1); + imx_uart_write(uart, UCR1, ucr1 | UCR1_TRDYEN); +} + +static void imx_uart_stop_tx(struct serial_port *port) +{ + struct imx_uart *uart = port->uart; + uint32_t ucr1; + + ucr1 = imx_uart_read(uart, UCR1); + imx_uart_write(uart, UCR1, ucr1 & ~UCR1_TRDYEN); +} + +static struct uart_driver __read_mostly imx_uart_driver = { + .init_preirq = imx_uart_init_preirq, + .init_postirq = imx_uart_init_postirq, + .tx_ready = imx_uart_tx_ready, + .putc = imx_uart_putc, + .getc = imx_uart_getc, + .irq = imx_uart_irq, + .start_tx = imx_uart_start_tx, + .stop_tx = imx_uart_stop_tx, + .vuart_info = imx_uart_vuart_info, +}; + +static int __init imx_uart_init(struct dt_device_node *dev, const void *data) +{ + const char *config = data; + struct imx_uart *uart; + int res; + paddr_t addr, size; + + if ( strcmp(config, "") ) + printk("WARNING: UART configuration is not supported\n"); + + uart = &imx8m_com; + + res = dt_device_get_paddr(dev, 0, &addr, &size); + if ( res ) + { + printk("imx-uart: Unable to retrieve the base address of the UART\n"); + return res; + } + + res = platform_get_irq(dev, 0); + if ( res < 0 ) + { + printk("imx-uart: Unable to retrieve the IRQ\n"); + return -EINVAL; + } + uart->irq = res; + + uart->regs = ioremap_nocache(addr, size); + if ( !uart->regs ) + { + printk("imx-uart: Unable to map the UART memory\n"); + return -ENOMEM; + } + + uart->vuart.base_addr = addr; + uart->vuart.size = size; + uart->vuart.data_off = URTX0; + uart->vuart.status_off = UTS; + uart->vuart.status = UTS_TXEMPTY | UTS_RXEMPTY; + + /* Register with generic serial driver */ + serial_register_uart(SERHND_DTUART, &imx_uart_driver, uart); + + dt_device_set_used_by(dev, DOMID_XEN); + + return 0; +} + +static const struct dt_device_match imx_uart_dt_compat[] __initconst = +{ + DT_MATCH_COMPATIBLE("fsl,imx6q-uart"), + { /* sentinel */ }, +}; + +DT_DEVICE_START(imx_uart, "i.MX UART", DEVICE_SERIAL) + .dt_match = imx_uart_dt_compat, + .init = imx_uart_init, +DT_DEVICE_END + +/* + * Local variables: + * mode: C + * c-file-style: "BSD" + * c-basic-offset: 4 + * indent-tabs-mode: nil + * End: + */ -- 2.43.0