simulator: Rework dummy simulator code to user timer_irq / serial_irq

Change the simulator to use the generic timer_irq.c and serial_irq.c
code for (dummy) timer and io handling.  This is just to make the code
a better example for other developers (most micro-controllers will use
the timer_irq.c and serial_irq.c code).

Signed-off-by: Kevin O'Connor <kevin@koconnor.net>

6 files changed, 165 insertions, 109 deletions

diff --git a/src/generic/serial_irq.h b/src/generic/serial_irq.h
index 470c9dfa..9aa96ab1 100644
--- a/src/generic/serial_irq.h
+++ b/src/generic/serial_irq.h
@@ -1,6 +1,8 @@
 #ifndef __GENERIC_SERIAL_IRQ_H
 #define __GENERIC_SERIAL_IRQ_H
 
+#include <stdint.h> // uint32_t
+
 // callback provided by board specific code
 void serial_enable_tx_irq(void);
 
diff --git a/src/simulator/Kconfig b/src/simulator/Kconfig
index 9065bb00..bb74fad6 100644
--- a/src/simulator/Kconfig
+++ b/src/simulator/Kconfig
@@ -15,4 +15,12 @@ config SIMULATOR_SELECT
     select HAVE_GPIO_SPI
     select HAVE_GPIO_HARD_PWM
 
+config CLOCK_FREQ
+    int
+    default 20000000
+
+config SERIAL_BAUD
+    int
+    default 250000
+
 endif
diff --git a/src/simulator/Makefile b/src/simulator/Makefile
index 34cfa4c8..6447a38b 100644
--- a/src/simulator/Makefile
+++ b/src/simulator/Makefile
@@ -2,5 +2,6 @@
 
 dirs-y += src/simulator src/generic
 
-src-y += simulator/main.c simulator/gpio.c
+src-y += simulator/main.c simulator/gpio.c simulator/timer.c simulator/serial.c
 src-y += generic/crc16_ccitt.c generic/alloc.c
+src-y += generic/timer_irq.c generic/serial_irq.c
diff --git a/src/simulator/main.c b/src/simulator/main.c
index e0384611..6817bbc5 100644
--- a/src/simulator/main.c
+++ b/src/simulator/main.c
@@ -1,122 +1,15 @@
 // Main starting point for host simulator.
 //
-// Copyright (C) 2016  Kevin O'Connor <kevin@koconnor.net>
+// Copyright (C) 2016-2018  Kevin O'Connor <kevin@koconnor.net>
 //
 // This file may be distributed under the terms of the GNU GPLv3 license.
 
-#include <fcntl.h>
-#include <stdio.h>
-#include <unistd.h>
-#include "board/misc.h" // timer_from_us
-#include "board/irq.h" // irq_disable
 #include "sched.h" // sched_main
 
-
-/****************************************************************
- * Interrupts
- ****************************************************************/
-
-irqstatus_t Interrupt_off;
-
-void
-irq_disable(void)
-{
-    Interrupt_off = 1;
-    barrier();
-}
-
-void
-irq_enable(void)
-{
-    barrier();
-    Interrupt_off = 0;
-}
-
-irqstatus_t
-irq_save(void)
-{
-    irqstatus_t flag = Interrupt_off;
-    irq_disable();
-    return flag;
-}
-
-void
-irq_restore(irqstatus_t flag)
-{
-    barrier();
-    Interrupt_off = flag;
-}
-
-void
-irq_wait(void)
-{
-}
-
-void
-irq_poll(void)
-{
-}
-
-
-/****************************************************************
- * Timers
- ****************************************************************/
-
-uint32_t
-timer_from_us(uint32_t us)
-{
-    return 0; // XXX
-}
-
-uint8_t
-timer_is_before(uint32_t time1, uint32_t time2)
-{
-    return (int32_t)(time1 - time2) < 0;
-}
-
-uint32_t
-timer_read_time(void)
-{
-    return 0; // XXX
-}
-
-void
-timer_kick(void)
-{
-}
-
-
-/****************************************************************
- * Turn stdin/stdout into serial console
- ****************************************************************/
-
-// Encode and transmit a "response" message
-void
-console_sendf(const struct command_encoder *ce, va_list args)
-{
-}
-
-
-/****************************************************************
- * Startup
- ****************************************************************/
-
-// Periodically sleep so we don't consume all CPU
-void
-simu_pause(void)
-{
-    // XXX - should check that no timers are present.
-    usleep(1);
-}
-DECL_TASK(simu_pause);
-
 // Main entry point for simulator.
 int
 main(void)
 {
-    // Make stdin non-blocking
-    fcntl(STDIN_FILENO, F_SETFL, fcntl(STDIN_FILENO, F_GETFL, 0) | O_NONBLOCK);
-
     sched_main();
     return 0;
 }
diff --git a/src/simulator/serial.c b/src/simulator/serial.c
new file mode 100644
index 00000000..3c7d008d
--- /dev/null
+++ b/src/simulator/serial.c
@@ -0,0 +1,43 @@
+// Example code for interacting with serial_irq.c
+//
+// Copyright (C) 2018  Kevin O'Connor <kevin@koconnor.net>
+//
+// This file may be distributed under the terms of the GNU GPLv3 license.
+
+#include <fcntl.h> // fcntl
+#include <unistd.h> // STDIN_FILENO
+#include "board/serial_irq.h" // serial_get_tx_byte
+#include "sched.h" // DECL_INIT
+
+void
+serial_init(void)
+{
+    // Make stdin/stdout non-blocking
+    fcntl(STDIN_FILENO, F_SETFL, fcntl(STDIN_FILENO, F_GETFL, 0) | O_NONBLOCK);
+    fcntl(STDOUT_FILENO, F_SETFL, fcntl(STDOUT_FILENO, F_GETFL, 0) | O_NONBLOCK);
+}
+DECL_INIT(serial_init);
+
+static void
+do_uart(void)
+{
+    for (;;) {
+        uint8_t data;
+        int ret = serial_get_tx_byte(&data);
+        if (ret)
+            break;
+        else
+            write(STDOUT_FILENO, &data, sizeof(data));
+
+        // XXX - Normally the code would check if input data is
+        // available and call serial_rx_byte()
+    }
+}
+
+void
+serial_enable_tx_irq(void)
+{
+    // Normally this would enable the hardware irq, but we just call
+    // do_uart() directly in this demo code.
+    do_uart();
+}
diff --git a/src/simulator/timer.c b/src/simulator/timer.c
new file mode 100644
index 00000000..f30d463a
--- /dev/null
+++ b/src/simulator/timer.c
@@ -0,0 +1,109 @@
+// Example code for running timers in a polling mode
+//
+// Copyright (C) 2018  Kevin O'Connor <kevin@koconnor.net>
+//
+// This file may be distributed under the terms of the GNU GPLv3 license.
+
+#include <time.h> // struct timespec
+#include <unistd.h> // usleep
+#include "autoconf.h" // CONFIG_CLOCK_FREQ
+#include "board/irq.h" // irq_disable
+#include "board/misc.h" // timer_from_us
+#include "board/timer_irq.h" // timer_dispatch_many
+#include "command.h" // DECL_CONSTANT
+#include "sched.h" // DECL_INIT
+
+// Helper function that returns the system time as a 32bit counter
+static uint32_t
+get_system_time(void)
+{
+    struct timespec ts;
+    clock_gettime(CLOCK_MONOTONIC, &ts);
+    double t = (double)ts.tv_sec + (double)ts.tv_nsec * .000000001;
+    return (uint32_t)(t * CONFIG_CLOCK_FREQ);
+}
+
+
+/****************************************************************
+ * Timers
+ ****************************************************************/
+
+static uint32_t next_wake_time;
+
+// Return the current time (in absolute clock ticks).
+uint32_t
+timer_read_time(void)
+{
+    return get_system_time();
+}
+
+// Activate timer dispatch as soon as possible
+void
+timer_kick(void)
+{
+    next_wake_time = timer_read_time();
+}
+
+// Invoke timers - called below from irq_poll()
+static void
+do_timer_dispatch(void)
+{
+    next_wake_time = timer_dispatch_many();
+}
+
+void
+timer_init(void)
+{
+    timer_kick();
+}
+DECL_INIT(timer_init);
+
+
+/****************************************************************
+ * Interrupts
+ ****************************************************************/
+
+// Disable hardware interrupts
+void
+irq_disable(void)
+{
+}
+
+// Enable hardware interrupts
+void
+irq_enable(void)
+{
+}
+
+// Disable hardware interrupts in not already disabled
+irqstatus_t
+irq_save(void)
+{
+    return 0;
+}
+
+// Restore hardware interrupts to state from flag returned by irq_save()
+void
+irq_restore(irqstatus_t flag)
+{
+}
+
+// Atomically enable hardware interrupts and sleep processor until next irq
+void
+irq_wait(void)
+{
+    // XXX - sleep to prevent excessive cpu usage in simulator
+    usleep(1);
+
+    irq_poll();
+}
+
+// Check if an interrupt is active (used only on architectures that do
+// not have hardware interrupts)
+void
+irq_poll(void)
+{
+    uint32_t now = timer_read_time();
+    if (!timer_is_before(now, next_wake_time))
+        do_timer_dispatch();
+}