feat: Add UART support

This commit adds support for UART with interrupt possibility and
helper functions especially for RX path

Author: Dzarda7

src/target/base/include/target/uart.h

@@ -7,5 +7,101 @@
 #pragma once
 
 #include <stdint.h>
+#include <stdbool.h>
+#include "soc_caps.h"
 
+/**
+ * @brief UART port numbers
+ *
+ * Available UART ports depend on the chip's SOC_UART_HP_NUM capability.
+ */
+typedef enum {
+    UART_NUM_0,                         /*!< UART port 0 */
+    UART_NUM_1,                         /*!< UART port 1 */
+#if SOC_UART_HP_NUM > 2
+    UART_NUM_2,                         /*!< UART port 2 */
+#endif
+#if SOC_UART_HP_NUM > 3
+    UART_NUM_3,                         /*!< UART port 3 */
+#endif
+#if SOC_UART_HP_NUM > 4
+    UART_NUM_4,                         /*!< UART port 4 */
+#endif
+    UART_NUM_MAX,                       /*!< UART port max */
+} uart_port_t;
+
+#define UART_INTR_RXFIFO_FULL      (0x1<<0)
+#define UART_INTR_RXFIFO_TOUT      (0x1<<8)
+
+/**
+ * @brief Wait until UART is idle
+ *
+ * @param uart_num UART port number
+ */
+void stub_target_uart_wait_idle(uint8_t uart_num);
+
+/**
+ * @brief Initialize UART
+ *
+ * @param uart_num UART port number
+ * @param baudrate Baud rate
+ */
 void stub_target_uart_init(uint8_t uart_num, uint32_t baudrate);
+
+/**
+ * @brief Set UART baud rate
+ *
+ * @param uart_num UART port number
+ * @param baudrate Baud rate
+ */
+void stub_target_uart_set_baudrate(uint8_t uart_num, uint32_t baudrate);
+
+/**
+ * @brief Attach interrupt handler to UART and configure interrupts
+ *
+ * @param uart_num UART port number
+ * @param intr_num CPU interrupt source
+ * @param handler Interrupt handler function pointer
+ * @param flags Interrupt enable flags (bitwise OR of UART_INTR_* values)
+ */
+void stub_target_uart_intr_attach(uint8_t uart_num, int intr_num, void *handler, uint32_t flags);
+
+/**
+ * @brief Get and clear UART interrupt status
+ *
+ * This function returns the interrupt status and automatically clears it.
+ * Call this at the beginning of your interrupt handler.
+ *
+ * @param uart_num UART port number
+ * @return Bitmask of active interrupts that were cleared
+ */
+uint32_t stub_target_uart_get_intr_flags(uint8_t uart_num);
+
+/**
+ * @brief Get number of bytes available in RX FIFO
+ *
+ * @param uart_num UART port number
+ * @return Number of bytes currently in the RX FIFO
+ */
+uint32_t stub_target_uart_get_rxfifo_count(uint8_t uart_num);
+
+/**
+ * @brief Read a single byte from UART RX FIFO
+ *
+ * This function reads one byte from the RX FIFO without checking
+ * if data is available. Call stub_target_uart_get_rxfifo_count()
+ * first to ensure data is available.
+ *
+ * @param uart_num UART port number
+ * @return The byte read from the FIFO
+ */
+uint8_t stub_target_uart_read_rxfifo_byte(uint8_t uart_num);
+
+/**
+ * @brief Configure RX timeout threshold
+ *
+ * @param uart_num UART port number
+ * @param timeout Timeout value in bit times (1-126, 0 to disable)
+ * timeout mean the multiple of UART packets (~11 bytes) that can be received before timeout
+ */
+void stub_target_uart_set_rx_timeout(uint8_t uart_num, uint8_t timeout);

src/target/common/src/uart.c

@@ -4,12 +4,80 @@
  * SPDX-License-Identifier: Apache-2.0 OR MIT
  */
 
+#include <stdbool.h>
 #include <stdint.h>
 #include <stddef.h>
 #include <target/uart.h>
+#include <target/soc_utils.h>
+#include <soc/uart_reg.h>
+
+extern void ets_update_cpu_frequency(uint32_t ticks_per_us);
+extern void uartAttach(void *rxBuffer);
+extern void Uart_Init(uint8_t uart_no);
+extern uint32_t ets_clk_get_cpu_freq(void);
+extern void uart_tx_switch(uint8_t uart_no);
+extern void uart_tx_wait_idle(uint8_t uart_num);
+extern void uart_div_modify(uint8_t uart_no, uint32_t divisor);
+
+void __attribute__((weak)) stub_target_uart_wait_idle(uint8_t uart_num)
+{
+    uart_tx_wait_idle(uart_num);
+}
 
 void __attribute__((weak)) stub_target_uart_init(uint8_t uart_num, uint32_t baudrate)
 {
-    (void)baudrate;
+    ets_update_cpu_frequency(ets_clk_get_cpu_freq() / 1000000);
+    uartAttach(NULL);
+    Uart_Init(uart_num);
+    uart_tx_switch(uart_num);
+    stub_target_uart_set_baudrate(uart_num, baudrate);
+}
+
+void __attribute__((weak)) stub_target_uart_set_baudrate(uint8_t uart_num, uint32_t baudrate)
+{
+    uint32_t clock = ets_clk_get_cpu_freq() << 4;
+    uint32_t divisor = clock / baudrate;
+    stub_target_uart_wait_idle(uart_num);
+    uart_div_modify(uart_num, divisor);
+    // TODO: Consider decimal part
+}
+
+void __attribute__((weak)) stub_target_uart_intr_attach(uint8_t uart_num, int intr_num, void *handler, uint32_t flags)
+{
     (void)uart_num;
+    (void)intr_num;
+    (void)handler;
+    (void)flags;
+    // TODO: implement
+}
+
+uint32_t __attribute__((weak)) stub_target_uart_get_intr_flags(uint8_t uart_num)
+{
+    uint32_t status = READ_PERI_REG(UART_INT_ST_REG(uart_num));
+    // Clear the interrupts
+    WRITE_PERI_REG(UART_INT_CLR_REG(uart_num), status);
+    return status;
+}
+
+uint32_t __attribute__((weak)) stub_target_uart_get_rxfifo_count(uint8_t uart_num)
+{
+    uint32_t status = READ_PERI_REG(UART_STATUS_REG(uart_num));
+    return (status >> UART_RXFIFO_CNT_S) & UART_RXFIFO_CNT_V;
+}
+
+uint8_t __attribute__((weak)) stub_target_uart_read_rxfifo_byte(uint8_t uart_num)
+{
+    return (uint8_t)(READ_PERI_REG(UART_FIFO_REG(uart_num)) & UART_RXFIFO_RD_BYTE_V);
+}
+
+void __attribute__((weak)) stub_target_uart_set_rx_timeout(uint8_t uart_num, uint8_t timeout)
+{
+    uint32_t conf1 = READ_PERI_REG(UART_CONF1_REG(uart_num));
+    conf1 &= ~(UART_RX_TOUT_THRHD_M | UART_RX_TOUT_EN_M);
+
+    if (timeout > 0U) {
+        conf1 |= (((uint32_t)timeout & UART_RX_TOUT_THRHD_V) << UART_RX_TOUT_THRHD_S) | UART_RX_TOUT_EN;
+    }
+
+    WRITE_PERI_REG(UART_CONF1_REG(uart_num), conf1);
 }

src/target/esp32/CMakeLists.txt

@@ -7,6 +7,7 @@ add_library(${ESP_TARGET_LIB} STATIC ${srcs})
 
 target_link_options(${ESP_TARGET_LIB}
     PUBLIC -T${CMAKE_CURRENT_LIST_DIR}/ld/esp32.rom.ld
+    PUBLIC -T${CMAKE_CURRENT_LIST_DIR}/ld/esp32.rom.redefined.ld
     PUBLIC -T${CMAKE_CURRENT_LIST_DIR}/ld/esp32.rom.libc-funcs.ld
     PUBLIC -T${CMAKE_CURRENT_LIST_DIR}/ld/esp32.rom.libgcc.ld
 )