From 2d5832af1ef5b1addfb9c989af71e031331b4efe Mon Sep 17 00:00:00 2001
From: Tilman Sauerbeck <tilman@code-monkey.de>
Date: Sun, 7 Jul 2019 18:45:19 +0200
Subject: [PATCH] common: Add the systick module.

This implements various timer functions using the systick peripheral.
---
 SConscript.libcommon  |  2 ++
 src/common/lib.rs     |  1 +
 src/common/systick.c  | 38 ++++++++++++++++++++++
 src/common/systick.rs | 76 +++++++++++++++++++++++++++++++++++++++++++
 4 files changed, 117 insertions(+)
 create mode 100644 src/common/systick.c
 create mode 100644 src/common/systick.rs

diff --git a/SConscript.libcommon b/SConscript.libcommon
index 54d1aaa..227c80a 100644
--- a/SConscript.libcommon
+++ b/SConscript.libcommon
@@ -6,6 +6,7 @@ source_files_rs = [
     'src/common/register.rs',
     'src/common/nvic.rs',
     'src/common/clock.rs',
+    'src/common/systick.rs',
     'src/common/crc32.rs',
     'src/common/buffer.rs',
     'src/common/usb_serial.rs',
@@ -13,6 +14,7 @@ source_files_rs = [
 
 source_files_c = [
     'src/common/startup.c',
+    'src/common/systick.c',
     'src/common/ringbuf.c',
     'src/common/usb_device_ch9.c',
     'src/common/usb_device_dci.c',
diff --git a/src/common/lib.rs b/src/common/lib.rs
index dfe7b40..e93861e 100644
--- a/src/common/lib.rs
+++ b/src/common/lib.rs
@@ -28,6 +28,7 @@
 pub mod register;
 pub mod nvic;
 pub mod clock;
+pub mod systick;
 pub mod crc32;
 pub mod buffer;
 pub mod usb_serial;
diff --git a/src/common/systick.c b/src/common/systick.c
new file mode 100644
index 0000000..649cd81
--- /dev/null
+++ b/src/common/systick.c
@@ -0,0 +1,38 @@
+/*
+ * Copyright (c) 2019 Tilman Sauerbeck (tilman at code-monkey de)
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining
+ * a copy of this software and associated documentation files (the
+ * "Software"), to deal in the Software without restriction, including
+ * without limitation the rights to use, copy, modify, merge, publish,
+ * distribute, sublicense, and/or sell copies of the Software, and to
+ * permit persons to whom the Software is furnished to do so, subject to
+ * the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be
+ * included in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
+ * LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
+ * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+ * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ */
+
+#include <stdint.h>
+
+static volatile uint32_t jiffies;
+
+void
+SysTick_Handler (void)
+{
+	jiffies++;
+}
+
+uint32_t
+get_ticks ()
+{
+	return jiffies;
+}
diff --git a/src/common/systick.rs b/src/common/systick.rs
new file mode 100644
index 0000000..78730d3
--- /dev/null
+++ b/src/common/systick.rs
@@ -0,0 +1,76 @@
+/*
+ * Copyright (c) 2019 Tilman Sauerbeck (tilman at code-monkey de)
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining
+ * a copy of this software and associated documentation files (the
+ * "Software"), to deal in the Software without restriction, including
+ * without limitation the rights to use, copy, modify, merge, publish,
+ * distribute, sublicense, and/or sell copies of the Software, and to
+ * permit persons to whom the Software is furnished to do so, subject to
+ * the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be
+ * included in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
+ * LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
+ * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+ * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ */
+
+use register;
+
+type Reg32 = register::Register<u32>;
+
+const SYSTICK_BASE: u32 = 0xe000e010;
+
+const SYSTICK_CTRL: u32 = SYSTICK_BASE + 0x00;
+const SYSTICK_LOAD: u32 = SYSTICK_BASE + 0x04;
+const SYSTICK_VAL : u32 = SYSTICK_BASE + 0x08;
+
+pub const RESOLUTION_MS : u32 = 10;
+
+extern {
+    fn get_ticks() -> u32;
+}
+
+pub fn init() {
+    // Assuming a 48 MHz core clock.
+    let ticks = 48000000 / 1000 * RESOLUTION_MS;
+
+    let mut load = Reg32::new(SYSTICK_LOAD);
+    load.write(ticks - 1);
+
+    let mut val = Reg32::new(SYSTICK_VAL);
+    val.write(0);
+
+    let mut ctrl = Reg32::new(SYSTICK_CTRL);
+    ctrl.write(7);
+}
+
+pub fn now() -> u32 {
+    unsafe {
+        get_ticks()
+    }
+}
+
+pub fn delay_ms(timeout_ms: u32) {
+    let timeout_ticks = timeout_ms / RESOLUTION_MS;
+    let start_ticks = now();
+
+    while (now() - start_ticks) < timeout_ticks {
+    }
+}
+
+pub fn has_timeout_ms(start_ticks: u32, timeout_ms: u32) -> bool {
+    let timeout_ticks = timeout_ms / RESOLUTION_MS;
+
+    (now() - start_ticks) >= timeout_ticks
+}
+
+pub fn elapsed_ms(later_ticks: u32, earlier_ticks: u32) -> u32 {
+    (later_ticks - earlier_ticks) * RESOLUTION_MS
+}
-- 
2.30.2