intelfb: add vsync interrupt support

[03/05] intelfb: Implement basic interrupt handling

Functions have been added to enable and disable interrupts using the MMIO registers. Currently only pipe A vsync interrupts are enabled.
A generalized vsync accounting struct is defined, with the intent that it can encapsulate per-pipe vsync related info in the future. Currently a single instance is hard-coded.
The interrupt service routine currently only looks for vsync interrupts on pipe A, and increments a counter and wakes up anyone waiting on it.

This implementation is heavily influenced by similar implementations in the atyfb and matroxfb drivers.

Signed-off-by: Eric Hustvedt <ehustvedt@cecropia.com>

1 files changed, 76 insertions, 0 deletions

diff --git a/drivers/video/intelfb/intelfbhw.c b/drivers/video/intelfb/intelfbhw.c
index 05aded669cdb..1a698a7230e0 100644
--- a/drivers/video/intelfb/intelfbhw.c
+++ b/drivers/video/intelfb/intelfbhw.c
@@ -34,6 +34,7 @@
 #include <linux/pci.h>
 #include <linux/vmalloc.h>
 #include <linux/pagemap.h>
+#include <linux/interrupt.h>
 
 #include <asm/io.h>
 
@@ -1943,3 +1944,78 @@ intelfbhw_cursor_reset(struct intelfb_info *dinfo) {
                 addr += 16;
         }
 }
+
+static irqreturn_t
+intelfbhw_irq(int irq, void *dev_id, struct pt_regs *fp) {
+        int handled = 0;
+        u16 tmp;
+        struct intelfb_info *dinfo = (struct intelfb_info *)dev_id;
+
+        spin_lock(&dinfo->int_lock);
+
+        tmp = INREG16(IIR);
+        tmp &= VSYNC_PIPE_A_INTERRUPT;
+
+        if (tmp == 0) {
+                spin_unlock(&dinfo->int_lock);
+                return IRQ_RETVAL(handled);
+        }
+
+        OUTREG16(IIR, tmp);
+
+        if (tmp & VSYNC_PIPE_A_INTERRUPT) {
+                dinfo->vsync.count++;
+                wake_up_interruptible(&dinfo->vsync.wait);
+                handled = 1;
+        }
+
+        spin_unlock(&dinfo->int_lock);
+
+        return IRQ_RETVAL(handled);
+}
+
+int
+intelfbhw_enable_irq(struct intelfb_info *dinfo, int reenable) {
+
+        if (!test_and_set_bit(0, &dinfo->irq_flags)) {
+                if (request_irq(dinfo->pdev->irq, intelfbhw_irq, SA_SHIRQ, "intelfb", dinfo)) {
+                        clear_bit(0, &dinfo->irq_flags);
+                        return -EINVAL;
+                }
+
+                spin_lock_irq(&dinfo->int_lock);
+                OUTREG16(HWSTAM, 0xfffe);
+                OUTREG16(IMR, 0x0);
+                OUTREG16(IER, VSYNC_PIPE_A_INTERRUPT);
+                spin_unlock_irq(&dinfo->int_lock);
+        } else if (reenable) {
+                u16 ier;
+
+                spin_lock_irq(&dinfo->int_lock);
+                ier = INREG16(IER);
+                if ((ier & VSYNC_PIPE_A_INTERRUPT)) {
+                        DBG_MSG("someone disabled the IRQ [%08X]\n", ier);
+                        OUTREG(IER, VSYNC_PIPE_A_INTERRUPT);
+                }
+                spin_unlock_irq(&dinfo->int_lock);
+        }
+        return 0;
+}
+
+void
+intelfbhw_disable_irq(struct intelfb_info *dinfo) {
+        u16 tmp;
+
+        if (test_and_clear_bit(0, &dinfo->irq_flags)) {
+                spin_lock_irq(&dinfo->int_lock);
+                OUTREG16(HWSTAM, 0xffff);
+                OUTREG16(IMR, 0xffff);
+                OUTREG16(IER, 0x0);
+
+                tmp = INREG16(IIR);
+                OUTREG16(IIR, tmp);
+                spin_unlock_irq(&dinfo->int_lock);
+
+                free_irq(dinfo->pdev->irq, dinfo);
+        }
+}