Linux-2.6.12-rc2
Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.
Let it rip!
diff --git a/arch/sh/boards/dreamcast/irq.c b/arch/sh/boards/dreamcast/irq.c
new file mode 100644
index 0000000..b10a6b1
--- /dev/null
+++ b/arch/sh/boards/dreamcast/irq.c
@@ -0,0 +1,160 @@
+/*
+ * arch/sh/boards/dreamcast/irq.c
+ *
+ * Holly IRQ support for the Sega Dreamcast.
+ *
+ * Copyright (c) 2001, 2002 M. R. Brown <mrbrown@0xd6.org>
+ *
+ * This file is part of the LinuxDC project (www.linuxdc.org)
+ * Released under the terms of the GNU GPL v2.0
+ */
+
+#include <linux/irq.h>
+
+#include <asm/io.h>
+#include <asm/irq.h>
+#include <asm/dreamcast/sysasic.h>
+
+/* Dreamcast System ASIC Hardware Events -
+
+ The Dreamcast's System ASIC (a.k.a. Holly) is responsible for receiving
+ hardware events from system peripherals and triggering an SH7750 IRQ.
+ Hardware events can trigger IRQs 13, 11, or 9 depending on which bits are
+ set in the Event Mask Registers (EMRs). When a hardware event is
+ triggered, it's corresponding bit in the Event Status Registers (ESRs)
+ is set, and that bit should be rewritten to the ESR to acknowledge that
+ event.
+
+ There are three 32-bit ESRs located at 0xa05f8900 - 0xa05f6908. Event
+ types can be found in include/asm-sh/dc_sysasic.h. There are three groups
+ of EMRs that parallel the ESRs. Each EMR group corresponds to an IRQ, so
+ 0xa05f6910 - 0xa05f6918 triggers IRQ 13, 0xa05f6920 - 0xa05f6928 triggers
+ IRQ 11, and 0xa05f6930 - 0xa05f6938 triggers IRQ 9.
+
+ In the kernel, these events are mapped to virtual IRQs so that drivers can
+ respond to them as they would a normal interrupt. In order to keep this
+ mapping simple, the events are mapped as:
+
+ 6900/6910 - Events 0-31, IRQ 13
+ 6904/6924 - Events 32-63, IRQ 11
+ 6908/6938 - Events 64-95, IRQ 9
+
+*/
+
+#define ESR_BASE 0x005f6900 /* Base event status register */
+#define EMR_BASE 0x005f6910 /* Base event mask register */
+
+/* Helps us determine the EMR group that this event belongs to: 0 = 0x6910,
+ 1 = 0x6920, 2 = 0x6930; also determine the event offset */
+#define LEVEL(event) (((event) - HW_EVENT_IRQ_BASE) / 32)
+
+/* Return the hardware event's bit positon within the EMR/ESR */
+#define EVENT_BIT(event) (((event) - HW_EVENT_IRQ_BASE) & 31)
+
+/* For each of these *_irq routines, the IRQ passed in is the virtual IRQ
+ (logically mapped to the corresponding bit for the hardware event). */
+
+/* Disable the hardware event by masking its bit in its EMR */
+static inline void disable_systemasic_irq(unsigned int irq)
+{
+ unsigned long flags;
+ __u32 emr = EMR_BASE + (LEVEL(irq) << 4) + (LEVEL(irq) << 2);
+ __u32 mask;
+
+ local_irq_save(flags);
+ mask = inl(emr);
+ mask &= ~(1 << EVENT_BIT(irq));
+ outl(mask, emr);
+ local_irq_restore(flags);
+}
+
+/* Enable the hardware event by setting its bit in its EMR */
+static inline void enable_systemasic_irq(unsigned int irq)
+{
+ unsigned long flags;
+ __u32 emr = EMR_BASE + (LEVEL(irq) << 4) + (LEVEL(irq) << 2);
+ __u32 mask;
+
+ local_irq_save(flags);
+ mask = inl(emr);
+ mask |= (1 << EVENT_BIT(irq));
+ outl(mask, emr);
+ local_irq_restore(flags);
+}
+
+/* Acknowledge a hardware event by writing its bit back to its ESR */
+static void ack_systemasic_irq(unsigned int irq)
+{
+ __u32 esr = ESR_BASE + (LEVEL(irq) << 2);
+ disable_systemasic_irq(irq);
+ outl((1 << EVENT_BIT(irq)), esr);
+}
+
+/* After a IRQ has been ack'd and responded to, it needs to be renabled */
+static void end_systemasic_irq(unsigned int irq)
+{
+ if (!(irq_desc[irq].status & (IRQ_DISABLED|IRQ_INPROGRESS)))
+ enable_systemasic_irq(irq);
+}
+
+static unsigned int startup_systemasic_irq(unsigned int irq)
+{
+ enable_systemasic_irq(irq);
+
+ return 0;
+}
+
+static void shutdown_systemasic_irq(unsigned int irq)
+{
+ disable_systemasic_irq(irq);
+}
+
+struct hw_interrupt_type systemasic_int = {
+ .typename = "System ASIC",
+ .startup = startup_systemasic_irq,
+ .shutdown = shutdown_systemasic_irq,
+ .enable = enable_systemasic_irq,
+ .disable = disable_systemasic_irq,
+ .ack = ack_systemasic_irq,
+ .end = end_systemasic_irq,
+};
+
+/*
+ * Map the hardware event indicated by the processor IRQ to a virtual IRQ.
+ */
+int systemasic_irq_demux(int irq)
+{
+ __u32 emr, esr, status, level;
+ __u32 j, bit;
+
+ switch (irq) {
+ case 13:
+ level = 0;
+ break;
+ case 11:
+ level = 1;
+ break;
+ case 9:
+ level = 2;
+ break;
+ default:
+ return irq;
+ }
+ emr = EMR_BASE + (level << 4) + (level << 2);
+ esr = ESR_BASE + (level << 2);
+
+ /* Mask the ESR to filter any spurious, unwanted interrtupts */
+ status = inl(esr);
+ status &= inl(emr);
+
+ /* Now scan and find the first set bit as the event to map */
+ for (bit = 1, j = 0; j < 32; bit <<= 1, j++) {
+ if (status & bit) {
+ irq = HW_EVENT_IRQ_BASE + j + (level << 5);
+ return irq;
+ }
+ }
+
+ /* Not reached */
+ return irq;
+}