stm32: Unify enable_pclock() code

Unify the handling of the enable_pclock() and is_enabled_pclock() code
across all stm32 chips.  All chips will now perform a peripheral reset
on enable_pclock() (this is a change for stm32f0 and stm32h7).  The
enable_pclock() code will now also disable irqs during the enable.

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

src/stm32/clockline.c

@@ -0,0 +1,32 @@
+// Code to enable clock lines on stm32
+//
+// Copyright (C) 2021  Kevin O'Connor <kevin@koconnor.net>
+//
+// This file may be distributed under the terms of the GNU GPLv3 license.
+
+#include "board/irq.h" // irq_save
+#include "internal.h" // struct cline
+
+// Enable a peripheral clock
+void
+enable_pclock(uint32_t periph_base)
+{
+    struct cline cl = lookup_clock_line(periph_base);
+    irqstatus_t flag = irq_save();
+    *cl.en |= cl.bit;
+    *cl.en; // Pause 2 cycles to ensure peripheral is enabled
+    if (cl.rst) {
+        // Reset peripheral
+        *cl.rst = cl.bit;
+        *cl.rst = 0;
+    }
+    irq_restore(flag);
+}
+
+// Check if a peripheral clock has been enabled
+int
+is_enabled_pclock(uint32_t periph_base)
+{
+    struct cline cl = lookup_clock_line(periph_base);
+    return *cl.en & cl.bit;
+}