Re: [PATCH 2/4] drivers/tty/serial: add driver for the ESP32 UART
From: Max Filippov
Date: Fri Sep 15 2023 - 18:36:05 EST
On Thu, Sep 14, 2023 at 6:07 AM Ilpo Järvinen
<ilpo.jarvinen@xxxxxxxxxxxxxxx> wrote:
>
> On Wed, 13 Sep 2023, Max Filippov wrote:
>
> > 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>
> > ---
> > drivers/tty/serial/Kconfig | 13 +
> > drivers/tty/serial/Makefile | 1 +
> > drivers/tty/serial/esp32_uart.c | 766 +++++++++++++++++++++++++++++++
> > include/uapi/linux/serial_core.h | 3 +
> > 4 files changed, 783 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..05ec0fce3a62
> > --- /dev/null
> > +++ b/drivers/tty/serial/esp32_uart.c
> > @@ -0,0 +1,766 @@
> > +// SPDX-License-Identifier: GPL-2.0-or-later
> > +
> > +#include <linux/clk.h>
> > +#include <linux/console.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 <linux/delay.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_MASK 0x00000001
> > +#define UART_TXFIFO_EMPTY_INT_MASK 0x00000002
> > +#define UART_BRK_DET_INT_MASK 0x00000080
>
> Use BIT() for these and do not call them MASK if they're just for a single
> flag bit.
Ok.
> > +#define UART_CLKDIV_REG 0x14
> > +#define ESP32_UART_CLKDIV_MASK 0x000fffff
> > +#define ESP32S3_UART_CLKDIV_MASK 0x00000fff
> > +#define UART_CLKDIV_SHIFT 0
>
> Use GENMASK() and drop the related *_SHIFT defines as
> FIELD_GET()/FIELD_PREP() will not need it.
Ok.
> Usually _MASK postfix is just waste of screen space and provides no useful
> information so consider dropping that as well from the names.
>
> > +#define UART_CLKDIV_FRAG_MASK 0x00f00000
> > +#define UART_CLKDIV_FRAG_SHIFT 20
> > +#define UART_STATUS_REG 0x1c
> > +#define ESP32_UART_RXFIFO_CNT_MASK 0x000000ff
> > +#define ESP32S3_UART_RXFIFO_CNT_MASK 0x000003ff
> > +#define UART_RXFIFO_CNT_SHIFT 0
> > +#define UART_DSRN_MASK 0x00002000
> > +#define UART_CTSN_MASK 0x00004000
> > +#define ESP32_UART_TXFIFO_CNT_MASK 0x00ff0000
> > +#define ESP32S3_UART_TXFIFO_CNT_MASK 0x03ff0000
> > +#define UART_TXFIFO_CNT_SHIFT 16
> > +#define UART_ST_UTX_OUT_MASK 0x0f000000
> > +#define UART_ST_UTX_OUT_IDLE 0x00000000
> > +#define UART_ST_UTX_OUT_SHIFT 24
> > +#define UART_CONF0_REG 0x20
> > +#define UART_PARITY_MASK 0x00000001
> > +#define UART_PARITY_EN_MASK 0x00000002
> > +#define UART_BIT_NUM_MASK 0x0000000c
> > +#define UART_BIT_NUM_5 0x00000000
> > +#define UART_BIT_NUM_6 0x00000004
> > +#define UART_BIT_NUM_7 0x00000008
> > +#define UART_BIT_NUM_8 0x0000000c
> > +#define UART_STOP_BIT_NUM_MASK 0x00000030
> > +#define UART_STOP_BIT_NUM_1 0x00000010
> > +#define UART_STOP_BIT_NUM_2 0x00000030
> > +#define UART_SW_RTS_MASK 0x00000040
> > +#define UART_SW_DTR_MASK 0x00000080
> > +#define UART_LOOPBACK_MASK 0x00004000
> > +#define UART_TX_FLOW_EN_MASK 0x00008000
> > +#define UART_RTS_INV_MASK 0x00800000
> > +#define UART_DTR_INV_MASK 0x01000000
> > +#define ESP32_UART_TICK_REF_ALWAYS_ON_MASK 0x08000000
> > +#define ESP32S3_UART_TICK_REF_ALWAYS_ON_MASK 0x00000000
> > +#define UART_CONF1_REG 0x24
> > +#define ESP32_UART_RXFIFO_FULL_THRHD_MASK 0x0000007f
> > +#define ESP32S3_UART_RXFIFO_FULL_THRHD_MASK 0x000003ff
> > +#define UART_RXFIFO_FULL_THRHD_SHIFT 0
> > +#define ESP32_UART_TXFIFO_EMPTY_THRHD_MASK 0x00007f00
> > +#define ESP32S3_UART_TXFIFO_EMPTY_THRHD_MASK 0x000ffc00
> > +#define ESP32_UART_TXFIFO_EMPTY_THRHD_SHIFT 8
> > +#define ESP32S3_UART_TXFIFO_EMPTY_THRHD_SHIFT 10
> > +#define ESP32_UART_RX_FLOW_EN_MASK 0x00800000
> > +#define ESP32S3_UART_RX_FLOW_EN_MASK 0x00400000
> > +
> > +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 rxfifo_full_thrhd_mask;
> > + u32 txfifo_empty_thrhd_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_MASK,
> > + .rxfifo_cnt_mask = ESP32_UART_RXFIFO_CNT_MASK,
> > + .txfifo_cnt_mask = ESP32_UART_TXFIFO_CNT_MASK,
> > + .rxfifo_full_thrhd_mask = ESP32_UART_RXFIFO_FULL_THRHD_MASK,
> > + .txfifo_empty_thrhd_mask = ESP32_UART_TXFIFO_EMPTY_THRHD_MASK,
> > + .txfifo_empty_thrhd_shift = ESP32_UART_TXFIFO_EMPTY_THRHD_SHIFT,
> > + .rx_flow_en = ESP32_UART_RX_FLOW_EN_MASK,
> > + .type = "ESP32 UART",
> > +};
> > +
> > +static const struct esp32_uart_variant esp32s3_variant = {
> > + .clkdiv_mask = ESP32S3_UART_CLKDIV_MASK,
> > + .rxfifo_cnt_mask = ESP32S3_UART_RXFIFO_CNT_MASK,
> > + .txfifo_cnt_mask = ESP32S3_UART_TXFIFO_CNT_MASK,
> > + .rxfifo_full_thrhd_mask = ESP32S3_UART_RXFIFO_FULL_THRHD_MASK,
> > + .txfifo_empty_thrhd_mask = ESP32S3_UART_TXFIFO_EMPTY_THRHD_MASK,
> > + .txfifo_empty_thrhd_shift = ESP32S3_UART_TXFIFO_EMPTY_THRHD_SHIFT,
> > + .rx_flow_en = ESP32S3_UART_RX_FLOW_EN_MASK,
> > + .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)
> > +{
> > + return (esp32_uart_read(port, UART_STATUS_REG) &
> > + port_variant(port)->txfifo_cnt_mask) >> UART_TXFIFO_CNT_SHIFT;
> > +}
> > +
> > +static u32 esp32_uart_rx_fifo_cnt(struct uart_port *port)
> > +{
> > + return (esp32_uart_read(port, UART_STATUS_REG) &
> > + port_variant(port)->rxfifo_cnt_mask) >> UART_RXFIFO_CNT_SHIFT;
>
> FIELD_GET().
I see how FIELD_GET can be used in other places, but here
port_variant(port)->rxfifo_cnt_mask is not a runtime constant and
FIELD_GET does not work with non-constant field definitions. Any
suggestions?
> Use more lines (and a local variable) instead of splitting one line. It
> will be more readable that way.
Ok.
> > +}
> > +
> > +/* return TIOCSER_TEMT when transmitter is not busy */
> > +static unsigned int esp32_uart_tx_empty(struct uart_port *port)
> > +{
> > + u32 status = esp32_uart_read(port, UART_STATUS_REG) &
> > + (port_variant(port)->txfifo_cnt_mask | UART_ST_UTX_OUT_MASK);
>
> Ditto.
>
> > +
> > + pr_debug("%s: %08x\n", __func__, status);
> > + return status == UART_ST_UTX_OUT_IDLE ? TIOCSER_TEMT : 0;
> > +}
> > +
> > +static void esp32_uart_set_mctrl(struct uart_port *port, unsigned int mctrl)
> > +{
> > + u32 conf0 = esp32_uart_read(port, UART_CONF0_REG) &
> > + ~(UART_LOOPBACK_MASK |
> > + UART_SW_RTS_MASK | UART_RTS_INV_MASK |
> > + UART_SW_DTR_MASK | UART_DTR_INV_MASK);
>
> Ditto.
Ok.
> > + if (mctrl & TIOCM_RTS)
> > + conf0 |= UART_SW_RTS_MASK;
> > + if (mctrl & TIOCM_DTR)
> > + conf0 |= UART_SW_DTR_MASK;
> > + if (mctrl & TIOCM_LOOP)
> > + conf0 |= UART_LOOPBACK_MASK;
> > +
> > + 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_MASK)
> > + ret |= TIOCM_DSR;
> > + if (status & UART_CTSN_MASK)
> > + 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_MASK;
>
> > + esp32_uart_write(port, UART_INT_ENA_REG,
> > + int_ena & ~UART_TXFIFO_EMPTY_INT_MASK);
>
> Just int_ena is enough after adding the logic op on its own line.
Ok.
> > +}
> > +
> > +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_MASK;
> > + }
> > + 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, unsigned char c)
> > +{
> > + esp32_uart_write(port, UART_FIFO_REG, c);
> > +}
> > +
> > +static void esp32_uart_put_char_sync(struct uart_port *port, unsigned char c)
> > +{
> > + while (esp32_uart_tx_fifo_cnt(port) >= ESP32_UART_TX_FIFO_SIZE)
> > + cpu_relax();
> > + esp32_uart_put_char(port, c);
> > +}
> > +
> > +static void esp32_uart_transmit_buffer(struct uart_port *port)
> > +{
> > + struct circ_buf *xmit = &port->state->xmit;
> > + u32 tx_fifo_used = esp32_uart_tx_fifo_cnt(port);
> > +
> > + while (!uart_circ_empty(xmit) && tx_fifo_used < ESP32_UART_TX_FIFO_SIZE) {
> > + esp32_uart_put_char(port, xmit->buf[xmit->tail]);
> > + xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
> > + port->icount.tx++;
> > + ++tx_fifo_used;
> > + }
> > +
> > + if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
> > + uart_write_wakeup(port);
>
> Too much open-coding here. Please use the helpers (likely the ones which
> replace the whole tx loop + its common surrounding code).
Ok.
> > + if (uart_circ_empty(xmit)) {
> > + esp32_uart_stop_tx(port);
> > + } else {
> > + u32 int_ena;
> > +
> > + int_ena = esp32_uart_read(port, UART_INT_ENA_REG);
> > + esp32_uart_write(port, UART_INT_ENA_REG,
> > + int_ena | UART_TXFIFO_EMPTY_INT_MASK);
>
> Own line for logic op.
Ok.
> > + }
> > +}
> > +
> > +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_MASK | UART_BRK_DET_INT_MASK))
> > + esp32_uart_rxint(port);
> > + if (status & UART_TXFIFO_EMPTY_INT_MASK)
> > + esp32_uart_txint(port);
> > +
> > + esp32_uart_write(port, UART_INT_CLR_REG, status);
> > + return IRQ_HANDLED;
> > +}
> > +
> > +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);
> > + esp32_uart_write(port, UART_INT_ENA_REG,
> > + int_ena & ~UART_RXFIFO_FULL_INT_MASK);
>
> Ditto.
Ok.
> > +}
> > +
> > +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;
> > +
> > + spin_lock_irqsave(&port->lock, flags);
> > + esp32_uart_write(port, UART_CONF1_REG,
> > + (1 << UART_RXFIFO_FULL_THRHD_SHIFT) |
>
> Use FIELD_PREP()
>
> > + (1 << port_variant(port)->txfifo_empty_thrhd_shift));
> > + esp32_uart_write(port, UART_INT_CLR_REG,
> > + UART_RXFIFO_FULL_INT_MASK |
> > + UART_BRK_DET_INT_MASK);
>
> This fits to two lines (well one too, especially if you remove those
> _MASK postfixes).
Ok.
> > + esp32_uart_write(port, UART_INT_ENA_REG,
> > + UART_RXFIFO_FULL_INT_MASK |
> > + UART_BRK_DET_INT_MASK);
>
> Ditto.
Ok.
> > + spin_unlock_irqrestore(&port->lock, flags);
> > +
> > + ret = devm_request_irq(port->dev, port->irq, esp32_uart_int, 0,
> > + DRIVER_NAME, port);
> > +
> > + pr_debug("%s, request_irq: %d, conf1 = %08x, int_st = %08x, status = %08x\n",
> > + __func__, ret,
> > + 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 void 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 | (frag << UART_CLKDIV_FRAG_SHIFT));
>
> FIELD_PREP().
Ok.
> Also div be encapsulated into FIELD_PREP here even if it's
> shift is 0.
This field's mask, port_variant(port)->clkdiv_mask, is, again, not a runtime
constant. Any suggestion for this?
> > + } else {
> > + dev_warn(port->dev,
> > + "%s: %d baud is out of reach, setting %d\n",
> > + __func__, baud,
>
> Don't print __func__.
Ok.
> > + port->uartclk / port_variant(port)->clkdiv_mask);
> > + esp32_uart_write(port, UART_CLKDIV_REG,
> > + port_variant(port)->clkdiv_mask |
> > + UART_CLKDIV_FRAG_MASK);
>
> I think you want to make the meaning more obvious here by using
> FIELD_MAX(UART_CLKDIV_FRAG_MASK);
No. I think FIELD_MAX makes it less obvious, because to work properly
it must be not just
FIELD_MAX(UART_CLKDIV_FRAG),
but
FIELD_PREP(UART_CLKDIV_FRAG, FIELD_MAX(UART_CLKDIV_FRAG)).
> > + }
> > +}
> > +
> > +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;
> > +
> > + spin_lock_irqsave(&port->lock, flags);
> > + conf0 = esp32_uart_read(port, UART_CONF0_REG) &
> > + ~(UART_PARITY_EN_MASK | UART_PARITY_MASK |
> > + UART_BIT_NUM_MASK | UART_STOP_BIT_NUM_MASK);
> > + conf1 = esp32_uart_read(port, UART_CONF1_REG) &
> > + ~rx_flow_en;
>
> Split logic to oen lines please.
Ok.
> > +
> > + if (termios->c_cflag & PARENB) {
> > + conf0 |= UART_PARITY_EN_MASK;
> > + if (termios->c_cflag & PARODD)
> > + conf0 |= UART_PARITY_MASK;
> > + }
> > +
> > + switch (termios->c_cflag & CSIZE) {
> > + case CS5:
> > + conf0 |= UART_BIT_NUM_5;
> > + break;
> > + case CS6:
> > + conf0 |= UART_BIT_NUM_6;
> > + break;
> > + case CS7:
> > + conf0 |= UART_BIT_NUM_7;
> > + break;
> > + case CS8:
> > + conf0 |= UART_BIT_NUM_8;
> > + break;
> > + }
> > +
> > + if (termios->c_cflag & CSTOPB)
> > + conf0 |= UART_STOP_BIT_NUM_2;
> > + else
> > + conf0 |= UART_STOP_BIT_NUM_1;
> > +
> > + if (termios->c_cflag & CRTSCTS)
> > + conf1 |= rx_flow_en;
>
> If you don't support some bits, you should clear them (CMSPAR).
Ok.
> > + esp32_uart_write(port, UART_CONF0_REG, conf0);
> > + esp32_uart_write(port, UART_CONF1_REG, conf1);
> > + spin_unlock_irqrestore(&port->lock, flags);
> > +
> > + /*
> > + * esp32s3 may not support 9600, passing its minimal baud rate
> > + * as the min argument would trigger a WARN inside uart_get_baud_rate
> > + */
> > + baud = uart_get_baud_rate(port, termios, old,
> > + 0, port->uartclk / 16);
>
> This looks questionable solution to the problem mentioned in the comment.
> What happens when user asks for baudrates below the minimum supported one?
I'll change it to refuse to change to unsupported baud rate and set default
to 115200.
> You might need to do something touching the core code to handle the case
> where 9600 is not possible fallback.
I'd rather make a fallback to 115200, as it's a much more reasonable default.
> > + if (baud)
> > + esp32_uart_set_baud(port, baud);
> > +}
>
> set_termios() function lacks call to uart_update_timeout().
Fixed.
> > +
> > +static const char *esp32_uart_type(struct uart_port *port)
> > +{
> > + return port_variant(port)->type;
> > +}
> > +
> > +static void esp32_uart_release_port(struct uart_port *port)
> > +{
> > +}
> > +
> > +static int esp32_uart_request_port(struct uart_port *port)
> > +{
> > + return 0;
> > +}
> > +
> > +/* 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,
> > + .release_port = esp32_uart_release_port,
> > + .request_port = esp32_uart_request_port,
> > + .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, unsigned char 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;
> > + int locked = 1;
> > +
> > + if (port->sysrq)
> > + locked = 0;
> > + 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;
>
> This lacks newline after declarations.
Ok.
> > + /*
> > + * 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, unsigned char 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;
> > + 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);
>
> One line.
Ok.
> > + 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);
> > +
> > + ret = uart_add_one_port(&esp32_uart_reg, port);
> > + return ret;
> > +}
> > +
> > +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_DESCRIPTION("Espressif ESP32 UART driver.");
>
> Drop .
Ok.
> > +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 */
> >
>
> --
> i.
>
--
Thanks.
-- Max