[legacy, hal] Implement timer driver

Signed-off-by: Douglas Reis <[email protected]>

Author: engdoreis

sw/legacy/demo/lcd_st7735/main.cc

@@ -11,14 +11,14 @@ extern "C" {
 #include "lowrisc_logo.h"
 #include "sonata_system.h"
 #include "st7735/lcd_st7735.h"
-#include "timer.h"
 
 int coremark_main();
 }
 
 #include "spi.hh"
 #include "pwm.hh"
 #include "gpio.hh"
+#include "timer.hh"
 #include "platform.hh"
 
 #define SIMULATION 0
@@ -49,15 +49,10 @@ static uint32_t gpio_write(void *handle, bool cs, bool dc) {
   return 0;
 }
 
+Timer timer(platform::Timer::Timer0, SYSCLK_FREQ);
 static void timer_delay(uint32_t ms) {
 #if !SIMULATION
-  // Configure timer to trigger every 1 ms
-  timer_enable(SYSCLK_FREQ / 1000);
-  uint32_t timeout = get_elapsed_time() + ms;
-  while (get_elapsed_time() < timeout) {
-    asm volatile("wfi");
-  }
-  timer_disable();
+  timer.delay(ms);
 #endif
 }
 
@@ -89,14 +84,12 @@ static Buttons_t scan_buttons(uint32_t timeout) {
 }
 
 int main(void) {
-  timer_init();
-
   // Init spi driver.
   Lcd spi(platform::Spi::SpiLcd);
 
   // Turn on LCD backlight via PWM
-  Pwm pwm(platform::Pwm::Pwm6);
-  pwm.set(1, 155);
+  Pwm pwm(platform::Pwm::PwmLcd);
+  pwm.set(1, 255);
 
   // Set the initial state of the LCD control pins.
   spi.chip_select(false);

sw/legacy/hal/timer.hh

@@ -0,0 +1,42 @@
+// Copyright lowRISC contributors.
+// Licensed under the Apache License, Version 2.0, see LICENSE for details.
+// SPDX-License-Identifier: Apache-2.0
+
+#pragma once
+
+#include "mmio/timer.hh"
+#include "platform.hh"
+
+class Timer {
+ public:
+  const platform::Timer base_addr;
+  const std::size_t clock_hz;
+
+  constexpr Timer(platform::Timer base_addr, std::size_t clock) : base_addr(base_addr), clock_hz(clock) {
+    mmio::timer::Timer timer(base_addr);
+    timer.mtimecmph.value.write(std::numeric_limits<uint32_t>::max()).commit();
+    timer.mtimecmpl.value.write(std::numeric_limits<uint32_t>::max()).commit();
+  }
+
+  uint64_t get() {
+    mmio::timer::Timer timer(base_addr);
+    return static_cast<uint64_t>(timer.mtimeh.fetch().value.get()) << 32 | timer.mtimel.fetch().value.get();
+  }
+
+  void delay(uint64_t millis) {
+    uint64_t timeout = (millis * clock_hz / 1000) + get();
+    while (timeout > get());
+  }
+};
+
+class CountDown {
+  Timer& timer;
+  uint64_t timeout;
+
+ public:
+  CountDown(Timer& timer, uint64_t millis) : timer(timer) { timeout = (millis * timer.clock_hz / 1000) + timer.get(); }
+
+  bool has_timeout() { return timeout < timer.get(); }
+
+  void wait() { while (!has_timeout()); }
+};