[PATCH v4 04/10] serial: bflb_uart: add Bouffalolab UART Driver

Jisheng Zhang
2023-05-18T15:34:33Z

Add the driver for Bouffalolab UART IP which is found in Bouffalolab
SoCs such as bl808.

UART driver probe will create path named "/dev/ttySx".

Signed-off-by: Jisheng Zhang <jszhang@kernel.org>
---
drivers/tty/serial/Kconfig | 18 +
drivers/tty/serial/Makefile | 1 +
drivers/tty/serial/bflb_uart.c | 586 +++++++++++++++++++++++++++++++
include/uapi/linux/serial_core.h | 3 +
4 files changed, 608 insertions(+)
create mode 100644 drivers/tty/serial/bflb_uart.c

diff --git a/drivers/tty/serial/Kconfig b/drivers/tty/serial/Kconfig
index 398e5aac2e77..abc30a0713f5 100644
--- a/drivers/tty/serial/Kconfig
+++ b/drivers/tty/serial/Kconfig
@@ -179,6 +179,24 @@ config SERIAL_ATMEL_TTYAT

Say Y if you have an external 8250/16C550 UART. If unsure, say N.

+config SERIAL_BFLB
+ tristate "Bouffalolab serial port support"
+ select SERIAL_CORE
+ depends on COMMON_CLK
+ help
+ This enables the driver for the Bouffalolab's serial.
+
+config SERIAL_BFLB_CONSOLE
+ bool "Support for console on Bouffalolab serial port"
+ depends on SERIAL_BFLB=y
+ select SERIAL_CORE_CONSOLE
+ select SERIAL_EARLYCON
+ help
+ Say Y here if you wish to use a Bouffalolab UART as the
+ system console (the system console is the device which
+ receives all kernel messages and warnings and which allows
+ logins in single user mode) as /dev/ttySn.
+
config SERIAL_KGDB_NMI
bool "Serial console over KGDB NMI debugger port"
depends on KGDB_SERIAL_CONSOLE
diff --git a/drivers/tty/serial/Makefile b/drivers/tty/serial/Makefile
index cd9afd9e3018..5788a708d327 100644
--- a/drivers/tty/serial/Makefile
+++ b/drivers/tty/serial/Makefile
@@ -25,6 +25,7 @@ obj-$(CONFIG_SERIAL_8250) += 8250/

obj-$(CONFIG_SERIAL_AMBA_PL010) += amba-pl010.o
obj-$(CONFIG_SERIAL_AMBA_PL011) += amba-pl011.o
+obj-$(CONFIG_SERIAL_BFLB) += bflb_uart.o
obj-$(CONFIG_SERIAL_CLPS711X) += clps711x.o
obj-$(CONFIG_SERIAL_PXA_NON8250) += pxa.o
obj-$(CONFIG_SERIAL_SA1100) += sa1100.o
diff --git a/drivers/tty/serial/bflb_uart.c b/drivers/tty/serial/bflb_uart.c
new file mode 100644
index 000000000000..3f80bba8599a
--- /dev/null
+++ b/drivers/tty/serial/bflb_uart.c
@@ -0,0 +1,586 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Based on bflb_uart.c, by Bouffalolab team
+ *
+ * Copyright (C) 2022 Jisheng Zhang <jszhang@kernel.org>
+ */
+
+#include <linux/bitfield.h>
+#include <linux/clk.h>
+#include <linux/console.h>
+#include <linux/kernel.h>
+#include <linux/init.h>
+#include <linux/interrupt.h>
+#include <linux/io.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/serial.h>
+#include <linux/serial_core.h>
+#include <linux/tty.h>
+#include <linux/tty_flip.h>
+
+#define UART_UTX_CONFIG 0x00
+#define UART_CR_UTX_EN BIT(0)
+#define UART_CR_UTX_CTS_EN BIT(1)
+#define UART_CR_UTX_FRM_EN BIT(2)
+#define UART_CR_UTX_PRT_EN BIT(4)
+#define UART_CR_UTX_PRT_SEL BIT(5)
+#define UART_CR_UTX_BIT_CNT_D_MSK GENMASK(10, 8)
+#define UART_CR_UTX_BIT_CNT_P_MSK GENMASK(12, 11)
+#define UART_URX_CONFIG 0x04
+#define UART_CR_URX_EN BIT(0)
+#define UART_CR_URX_PRT_EN BIT(4)
+#define UART_CR_URX_PRT_SEL BIT(5)
+#define UART_CR_URX_BIT_CNT_D_MSK GENMASK(10, 8)
+#define UART_BIT_PRD 0x08
+#define UART_CR_UTX_BIT_PRD_MSK GENMASK(15, 0)
+#define UART_CR_URX_BIT_PRD_MSK GENMASK(31, 16)
+#define UART_DATA_CONFIG 0x0c
+#define UART_CR_UART_BIT_INV BIT(0)
+#define UART_URX_RTO_TIMER 0x18
+#define UART_CR_URX_RTO_VALUE_MSK GENMASK(7, 0)
+#define UART_SW_MODE 0x1c
+#define UART_INT_STS 0x20
+#define UART_UTX_END_INT BIT(0)
+#define UART_URX_END_INT BIT(1)
+#define UART_UTX_FIFO_INT BIT(2)
+#define UART_URX_FIFO_INT BIT(3)
+#define UART_URX_RTO_INT BIT(4)
+#define UART_URX_PCE_INT BIT(5)
+#define UART_UTX_FER_INT BIT(6)
+#define UART_URX_FER_INT BIT(7)
+#define UART_URX_LSE_INT BIT(8)
+#define UART_INT_MASK 0x24
+#define UART_INT_CLEAR 0x28
+#define UART_INT_EN 0x2c
+#define UART_STATUS 0x30
+#define UART_STS_UTX_BUS_BUSY BIT(0)
+#define UART_FIFO_CONFIG_0 0x80
+#define UART_DMA_TX_EN BIT(0)
+#define UART_DMA_RX_EN BIT(1)
+#define UART_TX_FIFO_CLR BIT(2)
+#define UART_RX_FIFO_CLR BIT(3)
+#define UART_TX_FIFO_OVERFLOW BIT(4)
+#define UART_TX_FIFO_UNDERFLOW BIT(5)
+#define UART_RX_FIFO_OVERFLOW BIT(6)
+#define UART_RX_FIFO_UNDERFLOW BIT(7)
+#define UART_FIFO_CONFIG_1 0x84
+#define UART_TX_FIFO_CNT_MSK GENMASK(5, 0)
+#define UART_RX_FIFO_CNT_MSK GENMASK(13, 8)
+#define UART_TX_FIFO_TH_MSK GENMASK(20, 16)
+#define UART_RX_FIFO_TH_MSK GENMASK(28, 24)
+#define UART_FIFO_WDATA 0x88
+#define UART_FIFO_RDATA 0x8c
+#define UART_FIFO_RDATA_MSK GENMASK(7, 0)
+
+#define BFLB_UART_MAXPORTS 8
+#define BFLB_UART_BAUD 2000000
+#define BFLB_UART_RX_FIFO_TH 7
+#define BFLB_UART_TX_FIFO_TH 15
+#define BFLB_UART_URX_RTO_TIME 0x4f
+
+struct bflb_uart_port {
+ struct uart_port port;
+ struct clk *clk;
+};
+
+static struct bflb_uart_port *bflb_uart_ports[BFLB_UART_MAXPORTS];
+
+static inline u32 rdl(struct uart_port *port, u32 reg)
+{
+ return readl_relaxed(port->membase + reg);
+}
+
+static inline void wrl(struct uart_port *port, u32 reg, u32 value)
+{
+ writel_relaxed(value, port->membase + reg);
+}
+
+static inline void wrb(struct uart_port *port, u32 reg, u8 value)
+{
+ writeb_relaxed(value, port->membase + reg);
+}
+
+static unsigned int bflb_uart_tx_empty(struct uart_port *port)
+{
+ return (rdl(port, UART_FIFO_CONFIG_1) & UART_TX_FIFO_CNT_MSK) ? TIOCSER_TEMT : 0;
+}
+
+static unsigned int bflb_uart_get_mctrl(struct uart_port *port)
+{
+ return TIOCM_CAR | TIOCM_DSR | TIOCM_CTS;
+}
+
+static void bflb_uart_set_mctrl(struct uart_port *port, unsigned int sigs)
+{
+}
+
+static void bflb_uart_start_tx(struct uart_port *port)
+{
+ u32 val;
+
+ val = rdl(port, UART_UTX_CONFIG);
+ val |= UART_CR_UTX_EN;
+ wrl(port, UART_UTX_CONFIG, val);
+
+ val = rdl(port, UART_FIFO_CONFIG_1);
+ val &= ~UART_TX_FIFO_TH_MSK;
+ val |= FIELD_PREP(UART_TX_FIFO_TH_MSK, BFLB_UART_TX_FIFO_TH);
+ wrl(port, UART_FIFO_CONFIG_1, val);
+
+ val = rdl(port, UART_INT_MASK);
+ val &= ~UART_UTX_FIFO_INT;
+ wrl(port, UART_INT_MASK, val);
+}
+
+static void bflb_uart_stop_tx(struct uart_port *port)
+{
+ u32 val;
+
+ val = rdl(port, UART_INT_MASK);
+ val |= UART_UTX_FIFO_INT;
+ wrl(port, UART_INT_MASK, val);
+}
+
+static void bflb_uart_stop_rx(struct uart_port *port)
+{
+ u32 val;
+
+ val = rdl(port, UART_URX_CONFIG);
+ val &= ~UART_CR_URX_EN;
+ wrl(port, UART_URX_CONFIG, val);
+
+ val = rdl(port, UART_INT_MASK);
+ val |= UART_URX_FIFO_INT | UART_URX_RTO_INT | UART_URX_FER_INT;
+ wrl(port, UART_INT_MASK, val);
+}
+
+static void bflb_uart_set_termios(struct uart_port *port,
+ struct ktermios *termios,
+ const struct ktermios *old)
+{
+ unsigned long flags;
+ u32 valt, valr, val;
+ unsigned int baud, min;
+
+ spin_lock_irqsave(&port->lock, flags);
+
+ /* set data length */
+ val = tty_get_char_size(termios->c_cflag) - 1;
+ valt = FIELD_PREP(UART_CR_UTX_BIT_CNT_D_MSK, val);
+
+ /* calculate parity */
+ termios->c_cflag &= ~CMSPAR; /* no support mark/space */
+ if (termios->c_cflag & PARENB) {
+ valt |= UART_CR_UTX_PRT_EN;
+ if (termios->c_cflag & PARODD)
+ valt |= UART_CR_UTX_PRT_SEL;
+ }
+
+ valr = valt;
+
+ /* calculate stop bits */
+ if (termios->c_cflag & CSTOPB)
+ val = 2;
+ else
+ val = 1;
+ valt |= FIELD_PREP(UART_CR_UTX_BIT_CNT_P_MSK, val);
+
+ /* flow control */
+ if (termios->c_cflag & CRTSCTS)
+ valt |= UART_CR_UTX_CTS_EN;
+
+ /* enable TX freerunning mode */
+ valt |= UART_CR_UTX_FRM_EN;
+
+ valt |= UART_CR_UTX_EN;
+ valr |= UART_CR_URX_EN;
+
+ wrl(port, UART_UTX_CONFIG, valt);
+ wrl(port, UART_URX_CONFIG, valr);
+
+ min = port->uartclk / (UART_CR_UTX_BIT_PRD_MSK + 1);
+ baud = uart_get_baud_rate(port, termios, old, min, 4000000);
+
+ val = DIV_ROUND_CLOSEST(port->uartclk, baud) - 1;
+ val = FIELD_PREP(UART_CR_UTX_BIT_PRD_MSK, val);
+ val |= FIELD_PREP(UART_CR_URX_BIT_PRD_MSK, val);
+ wrl(port, UART_BIT_PRD, val);
+
+ uart_update_timeout(port, termios->c_cflag, baud);
+
+ spin_unlock_irqrestore(&port->lock, flags);
+}
+
+static void bflb_uart_rx_chars(struct uart_port *port)
+{
+ u8 ch;
+
+ while (rdl(port, UART_FIFO_CONFIG_1) & UART_RX_FIFO_CNT_MSK) {
+ ch = FIELD_GET(UART_FIFO_RDATA_MSK, rdl(port, UART_FIFO_RDATA));
+ port->icount.rx++;
+
+ if (uart_handle_sysrq_char(port, ch))
+ continue;
+ uart_insert_char(port, 0, 0, ch, TTY_NORMAL);
+ }
+
+ spin_unlock(&port->lock);
+ tty_flip_buffer_push(&port->state->port);
+ spin_lock(&port->lock);
+}
+
+static void bflb_uart_tx_chars(struct uart_port *port)
+{
+ u8 ch;
+
+ uart_port_tx_limited(port, ch, BFLB_UART_TX_FIFO_TH,
+ true,
+ wrl(port, UART_FIFO_WDATA, ch),
+ ({}));
+}
+
+static irqreturn_t bflb_uart_interrupt(int irq, void *data)
+{
+ struct uart_port *port = data;
+ u32 isr, val;
+
+ isr = rdl(port, UART_INT_STS);
+ wrl(port, UART_INT_CLEAR, isr);
+
+ spin_lock(&port->lock);
+
+ if (isr & UART_URX_FER_INT) {
+ /* RX FIFO error interrupt */
+ val = rdl(port, UART_FIFO_CONFIG_0);
+ if (val & UART_RX_FIFO_OVERFLOW)
+ port->icount.overrun++;
+
+ val |= UART_RX_FIFO_CLR;
+ wrl(port, UART_FIFO_CONFIG_0, val);
+ }
+
+ if (isr & (UART_URX_FIFO_INT | UART_URX_RTO_INT))
+ bflb_uart_rx_chars(port);
+
+ if (isr & UART_UTX_FIFO_INT)
+ bflb_uart_tx_chars(port);
+
+ spin_unlock(&port->lock);
+
+ return IRQ_RETVAL(isr);
+}
+
+static void bflb_uart_config_port(struct uart_port *port, int flags)
+{
+ port->type = PORT_BFLB;
+}
+
+static int bflb_uart_startup(struct uart_port *port)
+{
+ unsigned long flags;
+ int ret;
+ u32 val;
+
+ ret = devm_request_irq(port->dev, port->irq, bflb_uart_interrupt,
+ IRQF_SHARED, port->name, port);
+ if (ret) {
+ dev_err(port->dev, "fail to request serial irq %d, ret=%d\n",
+ port->irq, ret);
+ return ret;
+ }
+
+ spin_lock_irqsave(&port->lock, flags);
+
+ wrl(port, UART_INT_MASK, ~0);
+
+ wrl(port, UART_DATA_CONFIG, 0);
+ wrl(port, UART_SW_MODE, 0);
+ wrl(port, UART_URX_RTO_TIMER, FIELD_PREP(UART_CR_URX_RTO_VALUE_MSK, BFLB_UART_URX_RTO_TIME));
+
+ val = rdl(port, UART_FIFO_CONFIG_1);
+ val &= ~UART_RX_FIFO_TH_MSK;
+ val |= FIELD_PREP(UART_RX_FIFO_TH_MSK, BFLB_UART_RX_FIFO_TH);
+ wrl(port, UART_FIFO_CONFIG_1, val);
+
+ /* Unmask RX interrupts now */
+ val = rdl(port, UART_INT_MASK);
+ val &= ~(UART_URX_FIFO_INT | UART_URX_RTO_INT | UART_URX_FER_INT);
+ wrl(port, UART_INT_MASK, val);
+
+ val = rdl(port, UART_UTX_CONFIG);
+ val |= UART_CR_UTX_EN;
+ wrl(port, UART_UTX_CONFIG, val);
+ val = rdl(port, UART_URX_CONFIG);
+ val |= UART_CR_URX_EN;
+ wrl(port, UART_URX_CONFIG, val);
+
+ spin_unlock_irqrestore(&port->lock, flags);
+
+ return 0;
+}
+
+static void bflb_uart_shutdown(struct uart_port *port)
+{
+ unsigned long flags;
+
+ spin_lock_irqsave(&port->lock, flags);
+ /* mask all interrupts now */
+ wrl(port, UART_INT_MASK, ~0);
+ spin_unlock_irqrestore(&port->lock, flags);
+}
+
+static const char *bflb_uart_type(struct uart_port *port)
+{
+ return (port->type == PORT_BFLB) ? "BFLB UART" : NULL;
+}
+
+static int bflb_uart_verify_port(struct uart_port *port,
+ struct serial_struct *ser)
+{
+ if (ser->type != PORT_UNKNOWN && ser->type != PORT_BFLB)
+ return -EINVAL;
+ return 0;
+}
+
+static const struct uart_ops bflb_uart_ops = {
+ .tx_empty = bflb_uart_tx_empty,
+ .get_mctrl = bflb_uart_get_mctrl,
+ .set_mctrl = bflb_uart_set_mctrl,
+ .start_tx = bflb_uart_start_tx,
+ .stop_tx = bflb_uart_stop_tx,
+ .stop_rx = bflb_uart_stop_rx,
+ .startup = bflb_uart_startup,
+ .shutdown = bflb_uart_shutdown,
+ .set_termios = bflb_uart_set_termios,
+ .type = bflb_uart_type,
+ .config_port = bflb_uart_config_port,
+ .verify_port = bflb_uart_verify_port,
+};
+
+#ifdef CONFIG_SERIAL_BFLB_CONSOLE
+static void bflb_console_putchar(struct uart_port *port, unsigned char ch)
+{
+ while (!(rdl(port, UART_FIFO_CONFIG_1) & UART_TX_FIFO_CNT_MSK))
+ cpu_relax();
+ wrb(port, UART_FIFO_WDATA, ch);
+}
+
+/*
+ * Interrupts are disabled on entering
+ */
+static void bflb_uart_console_write(struct console *co, const char *s,
+ u_int count)
+{
+ struct uart_port *port = &bflb_uart_ports[co->index]->port;
+ u32 status, reg, mask;
+
+ /* save then disable interrupts */
+ mask = rdl(port, UART_INT_MASK);
+ reg = ~0;
+ wrl(port, UART_INT_MASK, reg);
+
+ /* Make sure that tx is enabled */
+ reg = rdl(port, UART_UTX_CONFIG);
+ reg |= UART_CR_UTX_EN;
+ wrl(port, UART_UTX_CONFIG, reg);
+
+ uart_console_write(port, s, count, bflb_console_putchar);
+
+ /* wait for TX done */
+ do {
+ status = rdl(port, UART_STATUS);
+ } while ((status & UART_STS_UTX_BUS_BUSY));
+
+ /* restore IRQ mask */
+ wrl(port, UART_INT_MASK, mask);
+}
+
+static int bflb_uart_console_setup(struct console *co, char *options)
+{
+ struct uart_port *port;
+ struct bflb_uart_port *bp;
+ int baud = BFLB_UART_BAUD;
+ int bits = 8;
+ int parity = 'n';
+ int flow = 'n';
+ u32 val;
+
+ if (co->index >= BFLB_UART_MAXPORTS || co->index < 0)
+ return -EINVAL;
+
+ bp = bflb_uart_ports[co->index];
+ if (!bp)
+ /* Port not initialized yet - delay setup */
+ return -ENODEV;
+
+ port = &bp->port;
+
+ val = rdl(port, UART_UTX_CONFIG);
+ val |= UART_CR_UTX_EN;
+ wrl(port, UART_UTX_CONFIG, val);
+
+ if (options)
+ uart_parse_options(options, &baud, &parity, &bits, &flow);
+
+ return uart_set_options(port, co, baud, parity, bits, flow);
+}
+
+static struct uart_driver bflb_uart_driver;
+static struct console bflb_uart_console = {
+ .name = "ttyS",
+ .write = bflb_uart_console_write,
+ .device = uart_console_device,
+ .setup = bflb_uart_console_setup,
+ .flags = CON_PRINTBUFFER,
+ .index = -1,
+ .data = &bflb_uart_driver,
+};
+
+static int __init bflb_uart_console_init(void)
+{
+ register_console(&bflb_uart_console);
+ return 0;
+}
+console_initcall(bflb_uart_console_init);
+
+#define BFLB_UART_CONSOLE (&bflb_uart_console)
+
+static void bflb_uart_earlycon_write(struct console *co, const char *s,
+ unsigned int count)
+{
+ struct earlycon_device *dev = co->data;
+
+ uart_console_write(&dev->port, s, count, bflb_console_putchar);
+}
+
+static int __init bflb_uart_earlycon_setup(struct earlycon_device *dev,
+ const char *options)
+{
+ if (!dev->port.membase)
+ return -ENODEV;
+
+ dev->con->write = bflb_uart_earlycon_write;
+
+ return 0;
+}
+OF_EARLYCON_DECLARE(bflb_uart, "bouffalolab,bl808-uart", bflb_uart_earlycon_setup);
+
+#else
+
+#define BFLB_UART_CONSOLE NULL
+
+#endif /* CONFIG_SERIAL_BFLB_CONSOLE */
+
+static struct uart_driver bflb_uart_driver = {
+ .owner = THIS_MODULE,
+ .driver_name = "bflb_uart",
+ .dev_name = "ttyS",
+ .nr = BFLB_UART_MAXPORTS,
+ .cons = BFLB_UART_CONSOLE,
+};
+
+static int bflb_uart_probe(struct platform_device *pdev)
+{
+ struct uart_port *port;
+ struct bflb_uart_port *bp;
+ struct resource *res;
+ int index, irq;
+
+ index = of_alias_get_id(pdev->dev.of_node, "serial");
+ if (unlikely(index < 0 || index >= BFLB_UART_MAXPORTS)) {
+ dev_err(&pdev->dev, "got a wrong serial alias id %d\n", index);
+ return -EINVAL;
+ }
+
+ bp = devm_kzalloc(&pdev->dev, sizeof(*bp), GFP_KERNEL);
+ if (!bp)
+ return -ENOMEM;
+
+ bflb_uart_ports[index] = bp;
+ platform_set_drvdata(pdev, bp);
+ port = &bp->port;
+
+ res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+ port->membase = devm_ioremap_resource(&pdev->dev, res);
+ if (IS_ERR(port->membase))
+ return PTR_ERR(port->membase);
+
+ irq = platform_get_irq(pdev, 0);
+ if (irq < 0)
+ return irq;
+
+ port->mapbase = res->start;
+ port->irq = irq;
+ port->line = index;
+ port->type = PORT_BFLB;
+ port->iotype = UPIO_MEM;
+ port->fifosize = 32;
+ port->ops = &bflb_uart_ops;
+ port->flags = UPF_BOOT_AUTOCONF;
+ port->dev = &pdev->dev;
+ port->has_sysrq = IS_ENABLED(CONFIG_SERIAL_BFLB_CONSOLE);
+
+ bp->clk = devm_clk_get_enabled(&pdev->dev, NULL);
+ if (IS_ERR(bp->clk))
+ return PTR_ERR(bp->clk);
+ port->uartclk = clk_get_rate(bp->clk);
+
+ return uart_add_one_port(&bflb_uart_driver, port);
+}
+
+static int bflb_uart_remove(struct platform_device *pdev)
+{
+ struct bflb_uart_port *bp = platform_get_drvdata(pdev);
+
+ uart_remove_one_port(&bflb_uart_driver, &bp->port);
+ bflb_uart_ports[bp->port.line] = NULL;
+
+ return 0;
+}
+
+static const struct of_device_id bflb_uart_match[] = {
+ {
+ .compatible = "bouffalolab,bl808-uart",
+ },
+ {},
+};
+MODULE_DEVICE_TABLE(of, bflb_uart_match);
+
+static struct platform_driver bflb_uart_platform_driver = {
+ .probe = bflb_uart_probe,
+ .remove = bflb_uart_remove,
+ .driver = {
+ .name = "bflb_uart",
+ .of_match_table = of_match_ptr(bflb_uart_match),
+ },
+};
+
+static int __init bflb_uart_init(void)
+{
+ int ret;
+
+ ret = uart_register_driver(&bflb_uart_driver);
+ if (ret)
+ return ret;
+
+ ret = platform_driver_register(&bflb_uart_platform_driver);
+ if (ret)
+ uart_unregister_driver(&bflb_uart_driver);
+
+ return ret;
+}
+
+static void __exit bflb_uart_exit(void)
+{
+ platform_driver_unregister(&bflb_uart_platform_driver);
+ uart_unregister_driver(&bflb_uart_driver);
+}
+
+module_init(bflb_uart_init);
+module_exit(bflb_uart_exit);
+
+MODULE_DESCRIPTION("Bouffalolab UART driver");
+MODULE_AUTHOR("Jisheng Zhang <jszhang@kernel.org>");
+MODULE_LICENSE("GPL");
diff --git a/include/uapi/linux/serial_core.h b/include/uapi/linux/serial_core.h
index 281fa286555c..0651fcc8734f 100644
--- a/include/uapi/linux/serial_core.h
+++ b/include/uapi/linux/serial_core.h
@@ -279,4 +279,7 @@
/* Sunplus UART */
#define PORT_SUNPLUS 123

+/* Bouffalolab UART */
+#define PORT_BFLB 124
+
#endif /* _UAPILINUX_SERIAL_CORE_H */
--
2.40.0