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drivers: serial: Added rpi_pico driver over PIO
Implements a UART driver using PIO. Both PIOs are supported. Only polling API is supported. Only 8N1 mode is supported. Signed-off-by: Yonatan Schachter <yonatan.schachter@gmail.com>
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‎boards/arm/rpi_pico/doc/index.rst

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@@ -81,6 +81,9 @@ hardware features:
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* - Flash
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- :kconfig:option:`CONFIG_FLASH`
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- :dtcompatible:`raspberrypi,pico-flash`
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* - UART (PIO)
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- :kconfig:option:`CONFIG_SERIAL`
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- :dtcompatible:`raspberrypi,pico-uart-pio`
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Pin Mapping
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===========

‎drivers/serial/CMakeLists.txt

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@@ -36,6 +36,7 @@ zephyr_library_sources_ifdef(CONFIG_UART_PL011 uart_pl011.c)
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zephyr_library_sources_ifdef(CONFIG_UART_QUICKLOGIC_USBSERIALPORT_S3B uart_ql_usbserialport_s3b.c)
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zephyr_library_sources_ifdef(CONFIG_UART_RV32M1_LPUART uart_rv32m1_lpuart.c)
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zephyr_library_sources_ifdef(CONFIG_UART_RPI_PICO uart_rpi_pico.c)
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zephyr_library_sources_ifdef(CONFIG_UART_RPI_PICO_PIO uart_rpi_pico_pio.c)
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zephyr_library_sources_ifdef(CONFIG_UART_LITEUART uart_liteuart.c)
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zephyr_library_sources_ifdef(CONFIG_UART_RTT_DRIVER uart_rtt.c)
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zephyr_library_sources_ifdef(CONFIG_UART_XLNX_PS uart_xlnx_ps.c)

‎drivers/serial/Kconfig.rpi_pico

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@@ -9,3 +9,12 @@ config UART_RPI_PICO
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select PICOSDK_USE_UART
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select SERIAL_SUPPORT_INTERRUPT
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depends on RESET
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config UART_RPI_PICO_PIO
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bool "Raspberry Pi PIO UART driver"
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default y
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depends on DT_HAS_RASPBERRYPI_PICO_UART_PIO_ENABLED
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select SERIAL_HAS_DRIVER
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select PICOSDK_USE_PIO
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select PICOSDK_USE_CLAIM
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depends on RESET

‎drivers/serial/uart_rpi_pico_pio.c

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/*
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* Copyright (c) 2022, Yonatan Schachter
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*
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* SPDX-License-Identifier: Apache-2.0
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*/
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#include <zephyr/drivers/pinctrl.h>
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#include <zephyr/drivers/uart.h>
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#include <zephyr/drivers/misc/pio_rpi_pico/pio_rpi_pico.h>
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#include <hardware/pio.h>
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#include <hardware/clocks.h>
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#define DT_DRV_COMPAT raspberrypi_pico_uart_pio
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#define CYCLES_PER_BIT 8
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#define SIDESET_BIT_COUNT 2
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struct pio_uart_config {
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const struct device *piodev;
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const struct pinctrl_dev_config *pcfg;
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const uint32_t tx_pin;
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const uint32_t rx_pin;
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uint32_t baudrate;
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};
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struct pio_uart_data {
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size_t tx_sm;
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size_t rx_sm;
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};
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RPI_PICO_PIO_DEFINE_PROGRAM(uart_tx, 0, 3,
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/* .wrap_target */
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0x9fa0, /* 0: pull block side 1 [7] */
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0xf727, /* 1: set x, 7 side 0 [7] */
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0x6001, /* 2: out pins, 1 */
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0x0642, /* 3: jmp x--, 2 [6] */
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/* .wrap */
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);
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RPI_PICO_PIO_DEFINE_PROGRAM(uart_rx, 0, 8,
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/* .wrap_target */
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0x2020, /* 0: wait 0 pin, 0 */
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0xea27, /* 1: set x, 7 [10] */
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0x4001, /* 2: in pins, 1 */
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0x0642, /* 3: jmp x--, 2 [6] */
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0x00c8, /* 4: jmp pin, 8 */
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0xc014, /* 5: irq nowait 4 rel */
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0x20a0, /* 6: wait 1 pin, 0 */
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0x0000, /* 7: jmp 0 */
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0x8020, /* 8: push block */
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/* .wrap */
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);
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static int pio_uart_tx_init(PIO pio, uint32_t sm, uint32_t tx_pin, float div)
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{
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uint32_t offset;
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pio_sm_config sm_config;
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if (!pio_can_add_program(pio, RPI_PICO_PIO_GET_PROGRAM(uart_tx))) {
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return -EBUSY;
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}
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offset = pio_add_program(pio, RPI_PICO_PIO_GET_PROGRAM(uart_tx));
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sm_config = pio_get_default_sm_config();
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sm_config_set_sideset(&sm_config, SIDESET_BIT_COUNT, true, false);
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sm_config_set_out_shift(&sm_config, true, false, 0);
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sm_config_set_out_pins(&sm_config, tx_pin, 1);
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sm_config_set_sideset_pins(&sm_config, tx_pin);
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sm_config_set_fifo_join(&sm_config, PIO_FIFO_JOIN_TX);
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sm_config_set_clkdiv(&sm_config, div);
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sm_config_set_wrap(&sm_config,
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offset + RPI_PICO_PIO_GET_WRAP_TARGET(uart_tx),
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offset + RPI_PICO_PIO_GET_WRAP(uart_tx));
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pio_sm_set_pins_with_mask(pio, sm, BIT(tx_pin), BIT(tx_pin));
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pio_sm_set_pindirs_with_mask(pio, sm, BIT(tx_pin), BIT(tx_pin));
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pio_sm_init(pio, sm, offset, &sm_config);
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pio_sm_set_enabled(pio, sm, true);
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return 0;
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}
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static int pio_uart_rx_init(PIO pio, uint32_t sm, uint32_t rx_pin, float div)
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{
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pio_sm_config sm_config;
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uint32_t offset;
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if (!pio_can_add_program(pio, RPI_PICO_PIO_GET_PROGRAM(uart_rx))) {
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return -EBUSY;
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}
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offset = pio_add_program(pio, RPI_PICO_PIO_GET_PROGRAM(uart_rx));
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sm_config = pio_get_default_sm_config();
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pio_sm_set_consecutive_pindirs(pio, sm, rx_pin, 1, false);
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sm_config_set_in_pins(&sm_config, rx_pin);
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sm_config_set_jmp_pin(&sm_config, rx_pin);
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sm_config_set_in_shift(&sm_config, true, false, 0);
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sm_config_set_fifo_join(&sm_config, PIO_FIFO_JOIN_RX);
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sm_config_set_clkdiv(&sm_config, div);
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sm_config_set_wrap(&sm_config,
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offset + RPI_PICO_PIO_GET_WRAP_TARGET(uart_rx),
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offset + RPI_PICO_PIO_GET_WRAP(uart_rx));
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pio_sm_init(pio, sm, offset, &sm_config);
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pio_sm_set_enabled(pio, sm, true);
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return 0;
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}
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static int pio_uart_poll_in(const struct device *dev, unsigned char *c)
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{
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const struct pio_uart_config *config = dev->config;
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PIO pio = pio_rpi_pico_get_pio(config->piodev);
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struct pio_uart_data *data = dev->data;
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io_rw_8 *uart_rx_fifo_msb;
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/*
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* The rx FIFO is 4 bytes wide, add 3 to get the most significant
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* byte.
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*/
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uart_rx_fifo_msb = (io_rw_8 *)&pio->rxf[data->rx_sm] + 3;
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if (pio_sm_is_rx_fifo_empty(pio, data->rx_sm)) {
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return -1;
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}
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/* Accessing the FIFO pops the read word from it */
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*c = (char)*uart_rx_fifo_msb;
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return 0;
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}
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static void pio_uart_poll_out(const struct device *dev, unsigned char c)
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{
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const struct pio_uart_config *config = dev->config;
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struct pio_uart_data *data = dev->data;
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pio_sm_put_blocking(pio_rpi_pico_get_pio(config->piodev), data->tx_sm, (uint32_t)c);
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}
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static int pio_uart_init(const struct device *dev)
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{
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const struct pio_uart_config *config = dev->config;
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struct pio_uart_data *data = dev->data;
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float sm_clock_div;
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size_t tx_sm;
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size_t rx_sm;
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int retval;
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PIO pio;
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pio = pio_rpi_pico_get_pio(config->piodev);
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sm_clock_div = (float)clock_get_hz(clk_sys) / (CYCLES_PER_BIT * config->baudrate);
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retval = pio_rpi_pico_allocate_sm(config->piodev, &tx_sm);
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retval |= pio_rpi_pico_allocate_sm(config->piodev, &rx_sm);
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if (retval < 0) {
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return retval;
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}
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data->tx_sm = tx_sm;
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data->rx_sm = rx_sm;
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retval = pio_uart_tx_init(pio, tx_sm, config->tx_pin, sm_clock_div);
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if (retval < 0) {
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return retval;
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}
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retval = pio_uart_rx_init(pio, rx_sm, config->rx_pin, sm_clock_div);
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if (retval < 0) {
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return retval;
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}
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return pinctrl_apply_state(config->pcfg, PINCTRL_STATE_DEFAULT);
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}
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static const struct uart_driver_api pio_uart_driver_api = {
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.poll_in = pio_uart_poll_in,
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.poll_out = pio_uart_poll_out,
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};
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#define PIO_UART_INIT(idx) \
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PINCTRL_DT_INST_DEFINE(idx); \
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static const struct pio_uart_config pio_uart##idx##_config = { \
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.piodev = DEVICE_DT_GET(DT_INST_PARENT(idx)), \
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.pcfg = PINCTRL_DT_INST_DEV_CONFIG_GET(idx), \
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.tx_pin = DT_INST_RPI_PICO_PIO_PIN_BY_NAME(idx, default, 0, tx_pins, 0), \
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.rx_pin = DT_INST_RPI_PICO_PIO_PIN_BY_NAME(idx, default, 0, rx_pins, 0), \
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.baudrate = DT_INST_PROP(idx, current_speed), \
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}; \
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static struct pio_uart_data pio_uart##idx##_data; \
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\
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DEVICE_DT_INST_DEFINE(idx, &pio_uart_init, NULL, &pio_uart##idx##_data, \
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&pio_uart##idx##_config, POST_KERNEL, \
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CONFIG_SERIAL_INIT_PRIORITY, \
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&pio_uart_driver_api);
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DT_INST_FOREACH_STATUS_OKAY(PIO_UART_INIT)

‎dts/bindings/serial/raspberrypi,pico-uart-pio.yaml

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description: Raspberry Pi Pico PIO UART
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compatible: "raspberrypi,pico-uart-pio"
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include: [uart-controller.yaml, "raspberrypi,pico-pio-device.yaml"]

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