From 11f9a09bd3d71bac2e8587fdbe137a961ffb38f2 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Unai=20Uribarri=20Rodr=C3=ADguez?= <unaiur@gmail.com>
Date: Sun, 13 May 2018 15:25:14 +0200
Subject: [PATCH] Add UART interrupt dispatcher

ESP8266 UART ports share a single interrupt service routine (ISR).
This code adds an interrupt dispatcher that allows to define a
different ISR for each UART port.
---
 cores/esp8266/HardwareSerial.h | 10 +++++
 cores/esp8266/uart.c           | 75 +++++++++++++++++++++++++++-------
 cores/esp8266/uart.h           |  3 ++
 3 files changed, 74 insertions(+), 14 deletions(-)

diff --git a/cores/esp8266/HardwareSerial.h b/cores/esp8266/HardwareSerial.h
index 0333d4ca87..36f5dd8ce5 100644
--- a/cores/esp8266/HardwareSerial.h
+++ b/cores/esp8266/HardwareSerial.h
@@ -184,6 +184,16 @@ class HardwareSerial: public Stream
         return uart_has_overrun(_uart);
     }
 
+    void attachIsr(void (*isr)(void*), void *arg)
+    {
+	uart_isr_attach(_uart, isr, arg);
+    }
+
+    void detachIsr()
+    {
+	uart_isr_detach(_uart);
+    }
+
 protected:
     int _uart_nr;
     uart_t* _uart = nullptr;
diff --git a/cores/esp8266/uart.c b/cores/esp8266/uart.c
index 47814f7a9d..0e57b1c9fd 100644
--- a/cores/esp8266/uart.c
+++ b/cores/esp8266/uart.c
@@ -240,16 +240,70 @@ uart_resize_rx_buffer(uart_t* uart, size_t new_size)
     return uart->rx_buffer->size;
 }
 
+static ets_isr_t s_isr_ptr[2];
+static void * s_isr_arg[2];
 
+static void ICACHE_RAM_ATTR
+uart_isr_dispatcher(void *unused)
+{
+    (void)unused;
+    for (int nr = 0; nr < 2; ++nr)
+    {
+        if (USIS(nr))
+        {
+            if (s_isr_ptr[nr])
+            {
+                s_isr_ptr[nr](s_isr_arg[nr]);
+            }
+            else
+            {
+                USIE(nr) = 0;
+                USIC(nr) = USIS(nr);
+            }
+        }
+    }
+}
+
+void
+uart_isr_attach(uart_t* uart, void (*isr)(void*), void *arg)
+{
+    int nr = uart->uart_nr;
+    ETS_UART_INTR_DISABLE();
+    if (s_isr_ptr[0] == NULL && s_isr_ptr[1] == NULL)
+    {
+        ETS_UART_INTR_ATTACH(uart_isr_dispatcher, NULL);
+    }
+    s_isr_ptr[nr] = isr;
+    s_isr_arg[nr] = arg;
+    ETS_UART_INTR_ENABLE();
+}
+
+void
+uart_isr_detach(uart_t* uart)
+{
+    int nr = uart->uart_nr;
+    ETS_UART_INTR_DISABLE();
+    s_isr_ptr[nr] = NULL;
+    s_isr_arg[nr] = NULL;
+    USIE(nr) = 0;
+    USIC(nr) = USIS(nr);
+    if (s_isr_ptr[0] == NULL &&  s_isr_ptr[1] == NULL)
+    {
+        ETS_UART_INTR_ATTACH(NULL, NULL);
+    }
+    else
+    {
+        ETS_UART_INTR_ENABLE();
+    }
+}
 
 void ICACHE_RAM_ATTR 
 uart_isr(void * arg)
 {
     uart_t* uart = (uart_t*)arg;
-    if(uart == NULL || !uart->rx_enabled) 
+    if(!uart->rx_enabled)
     {
-        USIC(uart->uart_nr) = USIS(uart->uart_nr);
-        ETS_UART_INTR_DISABLE();
+        uart_isr_detach(uart);
         return;
     }
     if(USIS(uart->uart_nr) & ((1 << UIFF) | (1 << UITO)))
@@ -271,21 +325,15 @@ uart_start_isr(uart_t* uart)
     USC1(uart->uart_nr) = (100   << UCFFT) | (0x02 << UCTOT) | (1 <<UCTOE );
     USIC(uart->uart_nr) = 0xffff;
     USIE(uart->uart_nr) = (1 << UIFF) | (1 << UIFR) | (1 << UITO);
-    ETS_UART_INTR_ATTACH(uart_isr,  (void *)uart);
-    ETS_UART_INTR_ENABLE();
+    uart_isr_attach(uart, uart_isr, uart);
 }
 
 static void 
 uart_stop_isr(uart_t* uart)
 {
-    if(uart == NULL || !uart->rx_enabled)
-        return;
-
-    ETS_UART_INTR_DISABLE();
-    USC1(uart->uart_nr) = 0;
-    USIC(uart->uart_nr) = 0xffff;
-    USIE(uart->uart_nr) = 0;
-    ETS_UART_INTR_ATTACH(NULL, NULL);
+    uart_isr_detach(uart);
+    if(uart->rx_enabled)
+        USC1(uart->uart_nr) = 0;
 }
 
 
@@ -527,7 +575,6 @@ uart_uninit(uart_t* uart)
 
     if(uart->rx_enabled)
     {
-        uart_stop_isr(uart);
         free(uart->rx_buffer->buffer);
         free(uart->rx_buffer);
     }
diff --git a/cores/esp8266/uart.h b/cores/esp8266/uart.h
index 127c5d0ebb..1d098d4563 100644
--- a/cores/esp8266/uart.h
+++ b/cores/esp8266/uart.h
@@ -125,6 +125,9 @@ bool uart_rx_enabled(uart_t* uart);
 void uart_set_baudrate(uart_t* uart, int baud_rate);
 int uart_get_baudrate(uart_t* uart);
 
+void uart_isr_attach(uart_t* uart, void (*isr)(void*), void *arg);
+void uart_isr_detach(uart_t* uart);
+
 size_t uart_resize_rx_buffer(uart_t* uart, size_t new_size);
 
 size_t uart_write_char(uart_t* uart, char c);