]> git.ipfire.org Git - thirdparty/linux.git/commitdiff
drivers/tty/serial: add driver for the ESP32 UART
authorMax Filippov <jcmvbkbc@gmail.com>
Tue, 10 Oct 2023 08:59:24 +0000 (01:59 -0700)
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Mon, 16 Oct 2023 18:17:29 +0000 (20:17 +0200)
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@gmail.com>
Link: https://lore.kernel.org/r/20231010085926.1021667-4-jcmvbkbc@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
drivers/tty/serial/Kconfig
drivers/tty/serial/Makefile
drivers/tty/serial/esp32_uart.c [new file with mode: 0644]

index bdc568a4ab66930b963dabb94bdd0daf617cc03e..d9ca6b268f019db7540c4fa61ff805b98c7ca92a 100644 (file)
@@ -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
index f6b8c220dcfb6192b6c819ff6e040cabade2563f..e9e33400952d54289b2060ff9fc76afe1648722a 100644 (file)
@@ -37,6 +37,7 @@ obj-$(CONFIG_SERIAL_CLPS711X)         += clps711x.o
 obj-$(CONFIG_SERIAL_CPM)               += cpm_uart.o
 obj-$(CONFIG_SERIAL_CONEXANT_DIGICOLOR)        += digicolor-usart.o
 obj-$(CONFIG_SERIAL_DZ)                        += dz.o
+obj-$(CONFIG_SERIAL_ESP32)             += esp32_uart.o
 obj-$(CONFIG_SERIAL_FSL_LINFLEXUART)   += fsl_linflexuart.o
 obj-$(CONFIG_SERIAL_FSL_LPUART)                += fsl_lpuart.o
 obj-$(CONFIG_SERIAL_ICOM)              += icom.o
diff --git a/drivers/tty/serial/esp32_uart.c b/drivers/tty/serial/esp32_uart.c
new file mode 100644 (file)
index 0000000..8203347
--- /dev/null
@@ -0,0 +1,741 @@
+// 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);
+
+               if (!rx &&
+                   (esp32_uart_read(port, UART_INT_ST_REG) & UART_BRK_DET_INT)) {
+                       esp32_uart_write(port, UART_INT_CLR_REG, UART_BRK_DET_INT);
+                       ++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);
+                       ++port->icount.rx;
+               }
+       }
+       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 = jiffies + HZ;
+
+       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);
+       unsigned int pending;
+       u8 ch;
+
+       if (tx_fifo_used >= ESP32_UART_TX_FIFO_SIZE)
+               return;
+
+       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 = request_irq(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);
+
+       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);
+       free_irq(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_GENERIC;
+}
+
+#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_GENERIC;
+       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@gmail.com>");
+MODULE_LICENSE("GPL");