hw/timer/bcm2835: Support the timer COMPARE registers

This peripheral has 1 free-running timer and 4 compare registers.

Only the free-running timer is implemented. Add support the
COMPARE registers (each register is wired to an IRQ).

Reference: "BCM2835 ARM Peripherals" datasheet [*]
            chapter 12 "System Timer":

  The System Timer peripheral provides four 32-bit timer channels
  and a single 64-bit free running counter. Each channel has an
  output compare register, which is compared against the 32 least
  significant bits of the free running counter values. When the
  two values match, the system timer peripheral generates a signal
  to indicate a match for the appropriate channel. The match signal
  is then fed into the interrupt controller.

This peripheral is used since Linux 3.7, commit ee4af5696720
("ARM: bcm2835: add system timer").

[*] https://www.raspberrypi.org/app/uploads/2012/02/BCM2835-ARM-Peripherals.pdf

Signed-off-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Reviewed-by: Luc Michel <luc@lmichel.fr>
Message-id: 20201010203709.3116542-4-f4bug@amsat.org
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

1 files changed, 9 insertions, 2 deletions

diff --git a/include/hw/timer/bcm2835_systmr.h b/include/hw/timer/bcm2835_systmr.h
index f15788a78d..bd3097d746 100644
--- a/include/hw/timer/bcm2835_systmr.h
+++ b/include/hw/timer/bcm2835_systmr.h
@@ -11,6 +11,7 @@
 
 #include "hw/sysbus.h"
 #include "hw/irq.h"
+#include "qemu/timer.h"
 #include "qom/object.h"
 
 #define TYPE_BCM2835_SYSTIMER "bcm2835-sys-timer"
@@ -18,18 +19,24 @@ OBJECT_DECLARE_SIMPLE_TYPE(BCM2835SystemTimerState, BCM2835_SYSTIMER)
 
 #define BCM2835_SYSTIMER_COUNT 4
 
+typedef struct {
+    unsigned id;
+    QEMUTimer timer;
+    qemu_irq irq;
+    BCM2835SystemTimerState *state;
+} BCM2835SystemTimerCompare;
+
 struct BCM2835SystemTimerState {
     /*< private >*/
     SysBusDevice parent_obj;
 
     /*< public >*/
     MemoryRegion iomem;
-    qemu_irq irq;
-
     struct {
         uint32_t ctrl_status;
         uint32_t compare[BCM2835_SYSTIMER_COUNT];
     } reg;
+    BCM2835SystemTimerCompare tmr[BCM2835_SYSTIMER_COUNT];
 };
 
 #endif