[PATCH v2 3/5] drivers/tty/serial: add driver for the ESP32 UART
From: Max Filippov
Date: Tue Sep 19 2023 - 22:27:25 EST
Add driver for the UART controllers of the Espressif ESP32 and ESP32S3
SoCs. Hardware specification is available at the following URLs:
https://www.espressif.com/sites/default/files/documentation/esp32_technical_reference_manual_en.pdf
(Chapter 13 UART Controller)
https://www.espressif.com/sites/default/files/documentation/esp32-s3_technical_reference_manual_en.pdf
(Chapter 26 UART Controller)
Signed-off-by: Max Filippov <jcmvbkbc@xxxxxxxxx>
---
Changes v1->v2:
- redefine register fields using BIT and GENMASK
- drop _MASK suffix from register field definitions
- drop *_SHIFT definitions where possible
- drop unused rxfifo_full_thrhd_mask and txfifo_empty_thrhd_mask
- split register reads/writes and bitwise operations into multiple lines
- use u8 instead of unsigned char in internal functions
- add timeout to esp32_uart_put_char_sync
- use uart_port_tx_limited in esp32_uart_transmit_buffer
- use IRQ_RETVAL in esp32_uart_int
- disable clock in esp32_uart_startup in case devm_request_irq fails
- rearrange devm_request_irq with enabling IRQs in the UART registers
- drop empty esp32_uart_release_port and esp32_uart_request_port
- simplify esp32_uart_tx_empty
- mask out unsupported CMSPAR flag in termios->c_cflag in
esp32_uart_set_termios
- invoke uart_update_timeout in esp32_uart_set_termios
- drop MODULE_DESCRIPTION
- rearrange esp32_uart_set_baud: return bool indicating whether baud
rate was set or not, use it in the esp32_uart_set_termios to set the
default 115200
- turn 'locked' into bool in esp32_uart_console_write
- turn num_read into unsigned int in esp32_uart_earlycon_read
drivers/tty/serial/Kconfig | 13 +
drivers/tty/serial/Makefile | 1 +
drivers/tty/serial/esp32_uart.c | 749 +++++++++++++++++++++++++++++++
include/uapi/linux/serial_core.h | 3 +
4 files changed, 766 insertions(+)
create mode 100644 drivers/tty/serial/esp32_uart.c
diff --git a/drivers/tty/serial/Kconfig b/drivers/tty/serial/Kconfig
index bdc568a4ab66..d9ca6b268f01 100644
--- a/drivers/tty/serial/Kconfig
+++ b/drivers/tty/serial/Kconfig
@@ -1578,6 +1578,19 @@ config SERIAL_NUVOTON_MA35D1_CONSOLE
but you can alter that using a kernel command line option such as
"console=ttyNVTx".
+config SERIAL_ESP32
+ tristate "Espressif ESP32 UART support"
+ depends on XTENSA_PLATFORM_ESP32 || (COMPILE_TEST && OF)
+ select SERIAL_CORE
+ select SERIAL_CORE_CONSOLE
+ select SERIAL_EARLYCON
+ help
+ Driver for the UART controllers of the Espressif ESP32xx SoCs.
+ When earlycon option is enabled the following kernel command line
+ snippets may be used:
+ earlycon=esp32s3uart,mmio32,0x60000000,115200n8,40000000
+ earlycon=esp32uart,mmio32,0x3ff40000,115200n8
+
endmenu
config SERIAL_MCTRL_GPIO
diff --git a/drivers/tty/serial/Makefile b/drivers/tty/serial/Makefile
index 138abbc89738..7b73137df7f3 100644
--- a/drivers/tty/serial/Makefile
+++ b/drivers/tty/serial/Makefile
@@ -88,6 +88,7 @@ obj-$(CONFIG_SERIAL_MILBEAUT_USIO) += milbeaut_usio.o
obj-$(CONFIG_SERIAL_SIFIVE) += sifive.o
obj-$(CONFIG_SERIAL_LITEUART) += liteuart.o
obj-$(CONFIG_SERIAL_SUNPLUS) += sunplus-uart.o
+obj-$(CONFIG_SERIAL_ESP32) += esp32_uart.o
# GPIOLIB helpers for modem control lines
obj-$(CONFIG_SERIAL_MCTRL_GPIO) += serial_mctrl_gpio.o
diff --git a/drivers/tty/serial/esp32_uart.c b/drivers/tty/serial/esp32_uart.c
new file mode 100644
index 000000000000..8fd81f43a305
--- /dev/null
+++ b/drivers/tty/serial/esp32_uart.c
@@ -0,0 +1,749 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+#include <linux/bitfield.h>
+#include <linux/bits.h>
+#include <linux/clk.h>
+#include <linux/console.h>
+#include <linux/delay.h>
+#include <linux/io.h>
+#include <linux/irq.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/of_device.h>
+#include <linux/serial_core.h>
+#include <linux/slab.h>
+#include <linux/tty_flip.h>
+#include <asm/serial.h>
+
+#define DRIVER_NAME "esp32-uart"
+#define DEV_NAME "ttyS"
+#define UART_NR 3
+
+#define ESP32_UART_TX_FIFO_SIZE 127
+#define ESP32_UART_RX_FIFO_SIZE 127
+
+#define UART_FIFO_REG 0x00
+#define UART_INT_RAW_REG 0x04
+#define UART_INT_ST_REG 0x08
+#define UART_INT_ENA_REG 0x0c
+#define UART_INT_CLR_REG 0x10
+#define UART_RXFIFO_FULL_INT BIT(0)
+#define UART_TXFIFO_EMPTY_INT BIT(1)
+#define UART_BRK_DET_INT BIT(7)
+#define UART_CLKDIV_REG 0x14
+#define ESP32_UART_CLKDIV GENMASK(19, 0)
+#define ESP32S3_UART_CLKDIV GENMASK(11, 0)
+#define UART_CLKDIV_SHIFT 0
+#define UART_CLKDIV_FRAG GENMASK(23, 20)
+#define UART_STATUS_REG 0x1c
+#define ESP32_UART_RXFIFO_CNT GENMASK(7, 0)
+#define ESP32S3_UART_RXFIFO_CNT GENMASK(9, 0)
+#define UART_RXFIFO_CNT_SHIFT 0
+#define UART_DSRN BIT(13)
+#define UART_CTSN BIT(14)
+#define ESP32_UART_TXFIFO_CNT GENMASK(23, 16)
+#define ESP32S3_UART_TXFIFO_CNT GENMASK(25, 16)
+#define UART_TXFIFO_CNT_SHIFT 16
+#define UART_CONF0_REG 0x20
+#define UART_PARITY BIT(0)
+#define UART_PARITY_EN BIT(1)
+#define UART_BIT_NUM GENMASK(3, 2)
+#define UART_BIT_NUM_5 0
+#define UART_BIT_NUM_6 1
+#define UART_BIT_NUM_7 2
+#define UART_BIT_NUM_8 3
+#define UART_STOP_BIT_NUM GENMASK(5, 4)
+#define UART_STOP_BIT_NUM_1 1
+#define UART_STOP_BIT_NUM_2 3
+#define UART_SW_RTS BIT(6)
+#define UART_SW_DTR BIT(7)
+#define UART_LOOPBACK BIT(14)
+#define UART_TX_FLOW_EN BIT(15)
+#define UART_RTS_INV BIT(23)
+#define UART_DTR_INV BIT(24)
+#define UART_CONF1_REG 0x24
+#define UART_RXFIFO_FULL_THRHD_SHIFT 0
+#define ESP32_UART_TXFIFO_EMPTY_THRHD_SHIFT 8
+#define ESP32S3_UART_TXFIFO_EMPTY_THRHD_SHIFT 10
+#define ESP32_UART_RX_FLOW_EN BIT(23)
+#define ESP32S3_UART_RX_FLOW_EN BIT(22)
+
+struct esp32_port {
+ struct uart_port port;
+ struct clk *clk;
+};
+
+struct esp32_uart_variant {
+ u32 clkdiv_mask;
+ u32 rxfifo_cnt_mask;
+ u32 txfifo_cnt_mask;
+ u32 txfifo_empty_thrhd_shift;
+ u32 rx_flow_en;
+ const char *type;
+};
+
+static const struct esp32_uart_variant esp32_variant = {
+ .clkdiv_mask = ESP32_UART_CLKDIV,
+ .rxfifo_cnt_mask = ESP32_UART_RXFIFO_CNT,
+ .txfifo_cnt_mask = ESP32_UART_TXFIFO_CNT,
+ .txfifo_empty_thrhd_shift = ESP32_UART_TXFIFO_EMPTY_THRHD_SHIFT,
+ .rx_flow_en = ESP32_UART_RX_FLOW_EN,
+ .type = "ESP32 UART",
+};
+
+static const struct esp32_uart_variant esp32s3_variant = {
+ .clkdiv_mask = ESP32S3_UART_CLKDIV,
+ .rxfifo_cnt_mask = ESP32S3_UART_RXFIFO_CNT,
+ .txfifo_cnt_mask = ESP32S3_UART_TXFIFO_CNT,
+ .txfifo_empty_thrhd_shift = ESP32S3_UART_TXFIFO_EMPTY_THRHD_SHIFT,
+ .rx_flow_en = ESP32S3_UART_RX_FLOW_EN,
+ .type = "ESP32S3 UART",
+};
+
+static const struct of_device_id esp32_uart_dt_ids[] = {
+ {
+ .compatible = "esp,esp32-uart",
+ .data = &esp32_variant,
+ }, {
+ .compatible = "esp,esp32s3-uart",
+ .data = &esp32s3_variant,
+ }, { /* sentinel */ }
+};
+MODULE_DEVICE_TABLE(of, esp32_uart_dt_ids);
+
+static struct esp32_port *esp32_uart_ports[UART_NR];
+
+static const struct esp32_uart_variant *port_variant(struct uart_port *port)
+{
+ return port->private_data;
+}
+
+static void esp32_uart_write(struct uart_port *port, unsigned long reg, u32 v)
+{
+ writel(v, port->membase + reg);
+}
+
+static u32 esp32_uart_read(struct uart_port *port, unsigned long reg)
+{
+ return readl(port->membase + reg);
+}
+
+static u32 esp32_uart_tx_fifo_cnt(struct uart_port *port)
+{
+ u32 status = esp32_uart_read(port, UART_STATUS_REG);
+
+ return (status & port_variant(port)->txfifo_cnt_mask) >> UART_TXFIFO_CNT_SHIFT;
+}
+
+static u32 esp32_uart_rx_fifo_cnt(struct uart_port *port)
+{
+ u32 status = esp32_uart_read(port, UART_STATUS_REG);
+
+ return (status & port_variant(port)->rxfifo_cnt_mask) >> UART_RXFIFO_CNT_SHIFT;
+}
+
+/* return TIOCSER_TEMT when transmitter is not busy */
+static unsigned int esp32_uart_tx_empty(struct uart_port *port)
+{
+ return esp32_uart_tx_fifo_cnt(port) ? 0 : TIOCSER_TEMT;
+}
+
+static void esp32_uart_set_mctrl(struct uart_port *port, unsigned int mctrl)
+{
+ u32 conf0 = esp32_uart_read(port, UART_CONF0_REG);
+
+ conf0 &= ~(UART_LOOPBACK |
+ UART_SW_RTS | UART_RTS_INV |
+ UART_SW_DTR | UART_DTR_INV);
+
+ if (mctrl & TIOCM_RTS)
+ conf0 |= UART_SW_RTS;
+ if (mctrl & TIOCM_DTR)
+ conf0 |= UART_SW_DTR;
+ if (mctrl & TIOCM_LOOP)
+ conf0 |= UART_LOOPBACK;
+
+ esp32_uart_write(port, UART_CONF0_REG, conf0);
+}
+
+static unsigned int esp32_uart_get_mctrl(struct uart_port *port)
+{
+ u32 status = esp32_uart_read(port, UART_STATUS_REG);
+ unsigned int ret = TIOCM_CAR;
+
+ if (status & UART_DSRN)
+ ret |= TIOCM_DSR;
+ if (status & UART_CTSN)
+ ret |= TIOCM_CTS;
+
+ return ret;
+}
+
+static void esp32_uart_stop_tx(struct uart_port *port)
+{
+ u32 int_ena;
+
+ int_ena = esp32_uart_read(port, UART_INT_ENA_REG);
+ int_ena &= ~UART_TXFIFO_EMPTY_INT;
+ esp32_uart_write(port, UART_INT_ENA_REG, int_ena);
+}
+
+static void esp32_uart_rxint(struct uart_port *port)
+{
+ struct tty_port *tty_port = &port->state->port;
+ u32 rx_fifo_cnt = esp32_uart_rx_fifo_cnt(port);
+ unsigned long flags;
+ u32 i;
+
+ if (!rx_fifo_cnt)
+ return;
+
+ spin_lock_irqsave(&port->lock, flags);
+
+ for (i = 0; i < rx_fifo_cnt; ++i) {
+ u32 rx = esp32_uart_read(port, UART_FIFO_REG);
+ u32 brk = 0;
+
+ ++port->icount.rx;
+
+ if (!rx) {
+ brk = esp32_uart_read(port, UART_INT_ST_REG) &
+ UART_BRK_DET_INT;
+ }
+ if (brk) {
+ esp32_uart_write(port, UART_INT_CLR_REG, brk);
+ ++port->icount.brk;
+ uart_handle_break(port);
+ } else {
+ if (uart_handle_sysrq_char(port, (unsigned char)rx))
+ continue;
+ tty_insert_flip_char(tty_port, rx, TTY_NORMAL);
+ }
+ }
+ spin_unlock_irqrestore(&port->lock, flags);
+
+ tty_flip_buffer_push(tty_port);
+}
+
+static void esp32_uart_put_char(struct uart_port *port, u8 c)
+{
+ esp32_uart_write(port, UART_FIFO_REG, c);
+}
+
+static void esp32_uart_put_char_sync(struct uart_port *port, u8 c)
+{
+ unsigned long timeout;
+
+ timeout = jiffies + msecs_to_jiffies(1000);
+ while (esp32_uart_tx_fifo_cnt(port) >= ESP32_UART_TX_FIFO_SIZE) {
+ if (time_after(jiffies, timeout)) {
+ dev_warn(port->dev, "timeout waiting for TX FIFO\n");
+ return;
+ }
+ cpu_relax();
+ }
+ esp32_uart_put_char(port, c);
+}
+
+static void esp32_uart_transmit_buffer(struct uart_port *port)
+{
+ u32 tx_fifo_used = esp32_uart_tx_fifo_cnt(port);
+
+ if (tx_fifo_used < ESP32_UART_TX_FIFO_SIZE) {
+ unsigned int pending;
+ u8 ch;
+
+ pending = uart_port_tx_limited(port, ch,
+ ESP32_UART_TX_FIFO_SIZE - tx_fifo_used,
+ true, esp32_uart_put_char(port, ch),
+ ({}));
+ if (pending) {
+ u32 int_ena;
+
+ int_ena = esp32_uart_read(port, UART_INT_ENA_REG);
+ int_ena |= UART_TXFIFO_EMPTY_INT;
+ esp32_uart_write(port, UART_INT_ENA_REG, int_ena);
+ }
+ }
+}
+
+static void esp32_uart_txint(struct uart_port *port)
+{
+ esp32_uart_transmit_buffer(port);
+}
+
+static irqreturn_t esp32_uart_int(int irq, void *dev_id)
+{
+ struct uart_port *port = dev_id;
+ u32 status;
+
+ status = esp32_uart_read(port, UART_INT_ST_REG);
+
+ if (status & (UART_RXFIFO_FULL_INT | UART_BRK_DET_INT))
+ esp32_uart_rxint(port);
+ if (status & UART_TXFIFO_EMPTY_INT)
+ esp32_uart_txint(port);
+
+ esp32_uart_write(port, UART_INT_CLR_REG, status);
+ return IRQ_RETVAL(status);
+}
+
+static void esp32_uart_start_tx(struct uart_port *port)
+{
+ esp32_uart_transmit_buffer(port);
+}
+
+static void esp32_uart_stop_rx(struct uart_port *port)
+{
+ u32 int_ena;
+
+ int_ena = esp32_uart_read(port, UART_INT_ENA_REG);
+ int_ena &= ~UART_RXFIFO_FULL_INT;
+ esp32_uart_write(port, UART_INT_ENA_REG, int_ena);
+}
+
+static int esp32_uart_startup(struct uart_port *port)
+{
+ int ret = 0;
+ unsigned long flags;
+ struct esp32_port *sport = container_of(port, struct esp32_port, port);
+
+ ret = clk_prepare_enable(sport->clk);
+ if (ret)
+ return ret;
+
+ ret = devm_request_irq(port->dev, port->irq, esp32_uart_int, 0,
+ DRIVER_NAME, port);
+ if (ret) {
+ clk_disable_unprepare(sport->clk);
+ return ret;
+ }
+
+ spin_lock_irqsave(&port->lock, flags);
+ esp32_uart_write(port, UART_CONF1_REG,
+ (1 << UART_RXFIFO_FULL_THRHD_SHIFT) |
+ (1 << port_variant(port)->txfifo_empty_thrhd_shift));
+ esp32_uart_write(port, UART_INT_CLR_REG, UART_RXFIFO_FULL_INT | UART_BRK_DET_INT);
+ esp32_uart_write(port, UART_INT_ENA_REG, UART_RXFIFO_FULL_INT | UART_BRK_DET_INT);
+ spin_unlock_irqrestore(&port->lock, flags);
+
+ pr_debug("%s, conf1 = %08x, int_st = %08x, status = %08x\n",
+ __func__,
+ esp32_uart_read(port, UART_CONF1_REG),
+ esp32_uart_read(port, UART_INT_ST_REG),
+ esp32_uart_read(port, UART_STATUS_REG));
+ return ret;
+}
+
+static void esp32_uart_shutdown(struct uart_port *port)
+{
+ struct esp32_port *sport = container_of(port, struct esp32_port, port);
+
+ esp32_uart_write(port, UART_INT_ENA_REG, 0);
+ devm_free_irq(port->dev, port->irq, port);
+ clk_disable_unprepare(sport->clk);
+}
+
+static bool esp32_uart_set_baud(struct uart_port *port, u32 baud)
+{
+ u32 div = port->uartclk / baud;
+ u32 frag = (port->uartclk * 16) / baud - div * 16;
+
+ if (div <= port_variant(port)->clkdiv_mask) {
+ esp32_uart_write(port, UART_CLKDIV_REG,
+ div | FIELD_PREP(UART_CLKDIV_FRAG, frag));
+ return true;
+ }
+ return false;
+}
+
+static void esp32_uart_set_termios(struct uart_port *port,
+ struct ktermios *termios,
+ const struct ktermios *old)
+{
+ unsigned long flags;
+ u32 conf0, conf1;
+ u32 baud;
+ const u32 rx_flow_en = port_variant(port)->rx_flow_en;
+
+ termios->c_cflag &= ~CMSPAR;
+
+ baud = uart_get_baud_rate(port, termios, old,
+ port->uartclk / port_variant(port)->clkdiv_mask,
+ port->uartclk / 16);
+
+ spin_lock_irqsave(&port->lock, flags);
+
+ conf0 = esp32_uart_read(port, UART_CONF0_REG);
+ conf0 &= ~(UART_PARITY_EN | UART_PARITY | UART_BIT_NUM | UART_STOP_BIT_NUM);
+
+ conf1 = esp32_uart_read(port, UART_CONF1_REG);
+ conf1 &= ~rx_flow_en;
+
+ if (termios->c_cflag & PARENB) {
+ conf0 |= UART_PARITY_EN;
+ if (termios->c_cflag & PARODD)
+ conf0 |= UART_PARITY;
+ }
+
+ switch (termios->c_cflag & CSIZE) {
+ case CS5:
+ conf0 |= FIELD_PREP(UART_BIT_NUM, UART_BIT_NUM_5);
+ break;
+ case CS6:
+ conf0 |= FIELD_PREP(UART_BIT_NUM, UART_BIT_NUM_6);
+ break;
+ case CS7:
+ conf0 |= FIELD_PREP(UART_BIT_NUM, UART_BIT_NUM_7);
+ break;
+ case CS8:
+ conf0 |= FIELD_PREP(UART_BIT_NUM, UART_BIT_NUM_8);
+ break;
+ }
+
+ if (termios->c_cflag & CSTOPB)
+ conf0 |= FIELD_PREP(UART_STOP_BIT_NUM, UART_STOP_BIT_NUM_2);
+ else
+ conf0 |= FIELD_PREP(UART_STOP_BIT_NUM, UART_STOP_BIT_NUM_1);
+
+ if (termios->c_cflag & CRTSCTS)
+ conf1 |= rx_flow_en;
+
+ esp32_uart_write(port, UART_CONF0_REG, conf0);
+ esp32_uart_write(port, UART_CONF1_REG, conf1);
+
+ if (baud) {
+ esp32_uart_set_baud(port, baud);
+ uart_update_timeout(port, termios->c_cflag, baud);
+ } else {
+ if (esp32_uart_set_baud(port, 115200)) {
+ baud = 115200;
+ tty_termios_encode_baud_rate(termios, baud, baud);
+ uart_update_timeout(port, termios->c_cflag, baud);
+ } else {
+ dev_warn(port->dev,
+ "unable to set speed to %d baud or the default 115200\n",
+ baud);
+ }
+ }
+ spin_unlock_irqrestore(&port->lock, flags);
+}
+
+static const char *esp32_uart_type(struct uart_port *port)
+{
+ return port_variant(port)->type;
+}
+
+/* configure/auto-configure the port */
+static void esp32_uart_config_port(struct uart_port *port, int flags)
+{
+ if (flags & UART_CONFIG_TYPE)
+ port->type = PORT_ESP32UART;
+}
+
+#ifdef CONFIG_CONSOLE_POLL
+static int esp32_uart_poll_init(struct uart_port *port)
+{
+ struct esp32_port *sport = container_of(port, struct esp32_port, port);
+
+ return clk_prepare_enable(sport->clk);
+}
+
+static void esp32_uart_poll_put_char(struct uart_port *port, unsigned char c)
+{
+ esp32_uart_put_char_sync(port, c);
+}
+
+static int esp32_uart_poll_get_char(struct uart_port *port)
+{
+ if (esp32_uart_rx_fifo_cnt(port))
+ return esp32_uart_read(port, UART_FIFO_REG);
+ else
+ return NO_POLL_CHAR;
+
+}
+#endif
+
+static const struct uart_ops esp32_uart_pops = {
+ .tx_empty = esp32_uart_tx_empty,
+ .set_mctrl = esp32_uart_set_mctrl,
+ .get_mctrl = esp32_uart_get_mctrl,
+ .stop_tx = esp32_uart_stop_tx,
+ .start_tx = esp32_uart_start_tx,
+ .stop_rx = esp32_uart_stop_rx,
+ .startup = esp32_uart_startup,
+ .shutdown = esp32_uart_shutdown,
+ .set_termios = esp32_uart_set_termios,
+ .type = esp32_uart_type,
+ .config_port = esp32_uart_config_port,
+#ifdef CONFIG_CONSOLE_POLL
+ .poll_init = esp32_uart_poll_init,
+ .poll_put_char = esp32_uart_poll_put_char,
+ .poll_get_char = esp32_uart_poll_get_char,
+#endif
+};
+
+static void esp32_uart_console_putchar(struct uart_port *port, u8 c)
+{
+ esp32_uart_put_char_sync(port, c);
+}
+
+static void esp32_uart_string_write(struct uart_port *port, const char *s,
+ unsigned int count)
+{
+ uart_console_write(port, s, count, esp32_uart_console_putchar);
+}
+
+static void
+esp32_uart_console_write(struct console *co, const char *s, unsigned int count)
+{
+ struct esp32_port *sport = esp32_uart_ports[co->index];
+ struct uart_port *port = &sport->port;
+ unsigned long flags;
+ bool locked = true;
+
+ if (port->sysrq)
+ locked = false;
+ else if (oops_in_progress)
+ locked = spin_trylock_irqsave(&port->lock, flags);
+ else
+ spin_lock_irqsave(&port->lock, flags);
+
+ esp32_uart_string_write(port, s, count);
+
+ if (locked)
+ spin_unlock_irqrestore(&port->lock, flags);
+}
+
+static int __init esp32_uart_console_setup(struct console *co, char *options)
+{
+ struct esp32_port *sport;
+ int baud = 115200;
+ int bits = 8;
+ int parity = 'n';
+ int flow = 'n';
+ int ret;
+
+ /*
+ * check whether an invalid uart number has been specified, and
+ * if so, search for the first available port that does have
+ * console support.
+ */
+ if (co->index == -1 || co->index >= ARRAY_SIZE(esp32_uart_ports))
+ co->index = 0;
+
+ sport = esp32_uart_ports[co->index];
+ if (!sport)
+ return -ENODEV;
+
+ ret = clk_prepare_enable(sport->clk);
+ if (ret)
+ return ret;
+
+ if (options)
+ uart_parse_options(options, &baud, &parity, &bits, &flow);
+
+ return uart_set_options(&sport->port, co, baud, parity, bits, flow);
+}
+
+static int esp32_uart_console_exit(struct console *co)
+{
+ struct esp32_port *sport = esp32_uart_ports[co->index];
+
+ clk_disable_unprepare(sport->clk);
+ return 0;
+}
+
+static struct uart_driver esp32_uart_reg;
+static struct console esp32_uart_console = {
+ .name = DEV_NAME,
+ .write = esp32_uart_console_write,
+ .device = uart_console_device,
+ .setup = esp32_uart_console_setup,
+ .exit = esp32_uart_console_exit,
+ .flags = CON_PRINTBUFFER,
+ .index = -1,
+ .data = &esp32_uart_reg,
+};
+
+static void esp32_uart_earlycon_putchar(struct uart_port *port, u8 c)
+{
+ esp32_uart_put_char_sync(port, c);
+}
+
+static void esp32_uart_earlycon_write(struct console *con, const char *s,
+ unsigned int n)
+{
+ struct earlycon_device *dev = con->data;
+
+ uart_console_write(&dev->port, s, n, esp32_uart_earlycon_putchar);
+}
+
+#ifdef CONFIG_CONSOLE_POLL
+static int esp32_uart_earlycon_read(struct console *con, char *s, unsigned int n)
+{
+ struct earlycon_device *dev = con->data;
+ unsigned int num_read = 0;
+
+ while (num_read < n) {
+ int c = esp32_uart_poll_get_char(&dev->port);
+
+ if (c == NO_POLL_CHAR)
+ break;
+ s[num_read++] = c;
+ }
+ return num_read;
+}
+#endif
+
+static int __init esp32xx_uart_early_console_setup(struct earlycon_device *device,
+ const char *options)
+{
+ if (!device->port.membase)
+ return -ENODEV;
+
+ device->con->write = esp32_uart_earlycon_write;
+#ifdef CONFIG_CONSOLE_POLL
+ device->con->read = esp32_uart_earlycon_read;
+#endif
+ if (device->port.uartclk != BASE_BAUD * 16)
+ esp32_uart_set_baud(&device->port, device->baud);
+
+ return 0;
+}
+
+static int __init esp32_uart_early_console_setup(struct earlycon_device *device,
+ const char *options)
+{
+ device->port.private_data = (void *)&esp32_variant;
+ return esp32xx_uart_early_console_setup(device, options);
+}
+
+OF_EARLYCON_DECLARE(esp32uart, "esp,esp32-uart",
+ esp32_uart_early_console_setup);
+
+static int __init esp32s3_uart_early_console_setup(struct earlycon_device *device,
+ const char *options)
+{
+ device->port.private_data = (void *)&esp32s3_variant;
+ return esp32xx_uart_early_console_setup(device, options);
+}
+
+OF_EARLYCON_DECLARE(esp32s3uart, "esp,esp32s3-uart",
+ esp32s3_uart_early_console_setup);
+
+static struct uart_driver esp32_uart_reg = {
+ .owner = THIS_MODULE,
+ .driver_name = DRIVER_NAME,
+ .dev_name = DEV_NAME,
+ .nr = ARRAY_SIZE(esp32_uart_ports),
+ .cons = &esp32_uart_console,
+};
+
+static int esp32_uart_probe(struct platform_device *pdev)
+{
+ struct device_node *np = pdev->dev.of_node;
+ static const struct of_device_id *match;
+ struct uart_port *port;
+ struct esp32_port *sport;
+ struct resource *res;
+ int ret;
+
+ match = of_match_device(esp32_uart_dt_ids, &pdev->dev);
+ if (!match)
+ return -ENODEV;
+
+ sport = devm_kzalloc(&pdev->dev, sizeof(*sport), GFP_KERNEL);
+ if (!sport)
+ return -ENOMEM;
+
+ port = &sport->port;
+
+ ret = of_alias_get_id(np, "serial");
+ if (ret < 0) {
+ dev_err(&pdev->dev, "failed to get alias id, errno %d\n", ret);
+ return ret;
+ }
+ if (ret >= UART_NR) {
+ dev_err(&pdev->dev, "driver limited to %d serial ports\n", UART_NR);
+ return -ENOMEM;
+ }
+
+ port->line = ret;
+
+ res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+ if (!res)
+ return -ENODEV;
+
+ port->mapbase = res->start;
+ port->membase = devm_ioremap_resource(&pdev->dev, res);
+ if (IS_ERR(port->membase))
+ return PTR_ERR(port->membase);
+
+ sport->clk = devm_clk_get(&pdev->dev, NULL);
+ if (IS_ERR(sport->clk))
+ return PTR_ERR(sport->clk);
+
+ port->uartclk = clk_get_rate(sport->clk);
+ port->dev = &pdev->dev;
+ port->type = PORT_ESP32UART;
+ port->iotype = UPIO_MEM;
+ port->irq = platform_get_irq(pdev, 0);
+ port->ops = &esp32_uart_pops;
+ port->flags = UPF_BOOT_AUTOCONF;
+ port->has_sysrq = 1;
+ port->fifosize = ESP32_UART_TX_FIFO_SIZE;
+ port->private_data = (void *)match->data;
+
+ esp32_uart_ports[port->line] = sport;
+
+ platform_set_drvdata(pdev, port);
+
+ return uart_add_one_port(&esp32_uart_reg, port);
+}
+
+static int esp32_uart_remove(struct platform_device *pdev)
+{
+ struct uart_port *port = platform_get_drvdata(pdev);
+
+ uart_remove_one_port(&esp32_uart_reg, port);
+
+ return 0;
+}
+
+
+static struct platform_driver esp32_uart_driver = {
+ .probe = esp32_uart_probe,
+ .remove = esp32_uart_remove,
+ .driver = {
+ .name = DRIVER_NAME,
+ .of_match_table = esp32_uart_dt_ids,
+ },
+};
+
+static int __init esp32_uart_init(void)
+{
+ int ret;
+
+ ret = uart_register_driver(&esp32_uart_reg);
+ if (ret)
+ return ret;
+
+ ret = platform_driver_register(&esp32_uart_driver);
+ if (ret)
+ uart_unregister_driver(&esp32_uart_reg);
+
+ return ret;
+}
+
+static void __exit esp32_uart_exit(void)
+{
+ platform_driver_unregister(&esp32_uart_driver);
+ uart_unregister_driver(&esp32_uart_reg);
+}
+
+module_init(esp32_uart_init);
+module_exit(esp32_uart_exit);
+
+MODULE_AUTHOR("Max Filippov <jcmvbkbc@xxxxxxxxx>");
+MODULE_LICENSE("GPL");
diff --git a/include/uapi/linux/serial_core.h b/include/uapi/linux/serial_core.h
index add349889d0a..ff076d6be159 100644
--- a/include/uapi/linux/serial_core.h
+++ b/include/uapi/linux/serial_core.h
@@ -245,4 +245,7 @@
/* Sunplus UART */
#define PORT_SUNPLUS 123
+/* Espressif ESP32 UART */
+#define PORT_ESP32UART 124
+
#endif /* _UAPILINUX_SERIAL_CORE_H */
--
2.30.2