Simple driver for the SP804 timer

base/include/drivers/timer/sp804_base.h

@@ -0,0 +1,183 @@
+/*
+ * \brief  Basic driver for the ARM SP804 timer
+ * \author Martin stein
+ * \date   2012-04-23
+ */
+
+/*
+ * Copyright (C) 2012 Genode Labs GmbH
+ *
+ * This file is part of the Genode OS framework, which is distributed
+ * under the terms of the GNU General Public License version 2.
+ */
+
+#ifndef _BASE__INCLUDE__DRIVERS__TIMER__SP804_H_
+#define _BASE__INCLUDE__DRIVERS__TIMER__SP804_H_
+
+/* Genode includes */
+#include <util/mmio.h>
+
+namespace Genode
+{
+	/**
+	 * Basic driver for the ARM SP804 timer
+	 *
+	 * \detail  Uses only timer module 0
+	 */
+	template <unsigned long CLK>
+	class Sp804_base : public Mmio
+	{
+		enum {
+			TICS_PER_MS = CLK / 1000,
+			TICS_PER_US = TICS_PER_MS / 1000,
+
+			AVOID_INVALID_TEMPLATE_ARGS = 1 / TICS_PER_US,
+		};
+
+		/**
+		 * Holds value that shall be loaded to the timer value register
+		 */
+		struct Load : Register<0x0, 32> { };
+
+		/**
+		 * Raw interrupt status
+		 */
+		struct Ris : Register<0x10, 1> { };
+
+		/**
+		 * Background load register
+		 */
+		struct Bgload : Register<0x18, 32> { };
+
+		/**
+		 * Timer value register
+		 */
+		struct Value : Register<0x4, 32> { enum { MAX_VALUE = 0xffffffff }; };
+
+		/**
+		 * Timer control register
+		 */
+		struct Control : Register<0x8, 8>
+		{
+			struct Oneshot  : Bitfield<0,1> { };
+			struct Size     : Bitfield<1,1> { };
+			struct Pre      : Bitfield<2,2> { };
+			struct Int_en   : Bitfield<5,1> { };
+			struct Mode     : Bitfield<6,1> { };
+			struct Timer_en : Bitfield<7,1> { };
+		};
+
+		/**
+		 * Clears the timer interrupt
+		 */
+		struct Int_clr : Register<0xc, 1> { };
+
+		public:
+
+			/**
+			 * Constructor, clears interrupt output
+			 */
+			Sp804_base(addr_t const mmio_base) : Mmio(mmio_base) {
+				clear_interrupt(); }
+
+			/**
+			 * Run the timer in order that it raises IRQ when
+			 * it reaches zero, then stop
+			 *
+			 * \param  tics  Native timer value used to assess the delay
+			 *               of the timer interrupt as of this call
+			 */
+			void run_and_stop(unsigned long const tics)
+			{
+				/* Disable and configure timer for a one-shot */
+				clear_interrupt();
+				write<typename Control::Timer_en>(0);
+				write<Control>(Control::Timer_en::bits(0) |
+				               Control::Mode::bits(1) |
+				               Control::Int_en::bits(1) |
+				               Control::Pre::bits(0) |
+				               Control::Size::bits(1) |
+				               Control::Oneshot::bits(1));
+
+				/* Load value and enable timer */
+				write<Load>(tics);
+				write<typename Control::Timer_en>(1);
+			}
+
+			/**
+			 * Run the timer in order that it raises IRQ when
+			 * it reaches zero, then wrap and continue
+			 *
+			 * \param  tics  Native timer value used to assess the delay
+			 *               of the timer interrupt as of this call
+			 */
+			void run_and_wrap(unsigned long const tics)
+			{
+				/* Configure the timer in order that it reloads on 0 */
+				clear_interrupt();
+				write<typename Control::Timer_en>(0);
+				write<Control>(Control::Timer_en::bits(0) |
+				               Control::Mode::bits(1) |
+				               Control::Int_en::bits(1) |
+				               Control::Pre::bits(0) |
+				               Control::Size::bits(1) |
+				               Control::Oneshot::bits(0));
+
+				/* Start timer with the inital value */
+				write<Load>(tics);
+				write<typename Control::Timer_en>(1);
+
+				/* Ensure that the timer loads its max value instead of
+				 * the initial value when it reaches 0 in order that it
+				 * looks like it wraps */
+				write<Bgload>(max_value());
+			}
+
+			/**
+			 * Current timer value
+			 */
+			unsigned long value() const { return read<Value>(); }
+
+			/**
+			 * Get timer value and corresponding wrapped status of timer
+			 */
+			unsigned long value(bool & wrapped) const
+			{
+				typename Value::access_t v = read<Value>();
+				wrapped = (bool)read<Ris>();
+				if (!wrapped) return v;
+				return read<Value>();
+			}
+
+			/**
+			 * Clear interrupt output line
+			 */
+			void clear_interrupt() { write<Int_clr>(1); }
+
+			/**
+			 * Translate milliseconds to a native timer value
+			 */
+			static unsigned long ms_to_tics(unsigned long const ms) {
+				return ms * TICS_PER_MS; }
+
+			/**
+			 * Translate native timer value to microseconds
+			 */
+			static unsigned long tics_to_us(unsigned long const tics) {
+				return tics / TICS_PER_US; }
+
+			/**
+			 * Translate microseconds to a native timer value
+			 */
+			static unsigned long us_to_tics(unsigned long const tics) {
+				return tics / TICS_PER_US; }
+
+			/**
+			 * Translate native timer value to microseconds
+			 */
+			static unsigned long max_value() { return Value::MAX_VALUE; }
+	};
+}
+
+#endif /* _BASE__INCLUDE__DRIVERS__TIMER__SP804_H_ */
+