[Qemu-devel] [PATCH] Add support for parallel port interrupts

[Vijay Kumar]

Implement the interrupt chain for parallel ports. Receive interrupts
from /dev/parportX by registering read handlers. Convert parallel port
interrupts to char events (PPINT). Handle the event in the simulated
parallel port and raise the interrupt to the guest.

Signed-off-by: Vijay Kumar B. <address@hidden>

Index: qemu/hw/parallel.c
===================================================================
--- qemu.orig/hw/parallel.c     2009-04-21 19:14:34.000000000 +0530
+++ qemu/hw/parallel.c  2009-04-21 19:19:50.000000000 +0530
@@ -86,6 +86,22 @@
         qemu_irq_lower(s->irq);
 }
 
+static void parallel_event(void *opaque, int event)
+{
+    int i;
+    int irqc;
+    ParallelState *s = opaque;
+
+    pdebug("event %x\n", event);
+
+    if (event == CHR_EVENT_PPINT) {
+        /* Generate a pulse for each interrupt received. */
+        qemu_chr_ioctl(s->chr, CHR_IOCTL_PP_CLEAR_INT, &irqc);
+        for (i = 0; i < irqc; i++)
+            qemu_irq_pulse(s->irq);
+    }
+}
+
 static void
 parallel_ioport_write_sw(void *opaque, uint32_t addr, uint32_t val)
 {
@@ -165,6 +181,14 @@
             parm &= ~PARA_CTR_DIR;
         }
 
+        if ((val & PARA_CTR_INTEN) != (s->control & PARA_CTR_INTEN)) {
+            if (val & PARA_CTR_INTEN) {
+                qemu_chr_add_handlers(s->chr, NULL, NULL, parallel_event, s);
+            } else {
+                qemu_chr_add_handlers(s->chr, NULL, NULL, NULL, NULL);
+            }
+        }
+
         qemu_chr_ioctl(s->chr, CHR_IOCTL_PP_WRITE_CONTROL, &parm);
         s->control = val;
         break;
Index: qemu/qemu-char.h
===================================================================
--- qemu.orig/qemu-char.h       2009-04-21 19:14:34.000000000 +0530
+++ qemu/qemu-char.h    2009-04-21 19:14:41.000000000 +0530
@@ -11,6 +11,7 @@
 #define CHR_EVENT_RESET   2 /* new connection established */
 #define CHR_EVENT_MUX_IN  3 /* mux-focus was set to this terminal */
 #define CHR_EVENT_MUX_OUT 4 /* mux-focus will move on */
+#define CHR_EVENT_PPINT   5 /* parallel port interrupt occured */
 
 
 #define CHR_IOCTL_SERIAL_SET_PARAMS   1
@@ -37,6 +38,8 @@
 #define CHR_IOCTL_SERIAL_SET_TIOCM   13
 #define CHR_IOCTL_SERIAL_GET_TIOCM   14
 
+#define CHR_IOCTL_PP_CLEAR_INT       15
+
 #define CHR_TIOCM_CTS  0x020
 #define CHR_TIOCM_CAR  0x040
 #define CHR_TIOCM_DSR  0x100
Index: qemu/qemu-char.c
===================================================================
--- qemu.orig/qemu-char.c       2009-04-21 19:14:34.000000000 +0530
+++ qemu/qemu-char.c    2009-04-21 19:17:00.000000000 +0530
@@ -1202,6 +1202,10 @@
         if (ioctl(fd, PPDATADIR, (int *)arg) < 0)
             return -ENOTSUP;
         break;
+    case CHR_IOCTL_PP_CLEAR_INT:
+        if (ioctl(fd, PPCLRIRQ, (int *)arg) < 0)
+            return -ENOTSUP;
+        break;
     case CHR_IOCTL_PP_EPP_READ_ADDR:
        if (pp_hw_mode(drv, IEEE1284_MODE_EPP|IEEE1284_ADDR)) {
            struct ParallelIOArg *parg = arg;
@@ -1244,11 +1248,34 @@
     return 0;
 }
 
+/* When poll()ed, /dev/parportX reports a read event when an interrupt
+ * occurs. We register a handler pp_int_notify() to receive interrupt
+ * notifications. The character event mechanism is then used for
+ * reporting interrupts to the hw peripherals.
+ */
+
+static void pp_int_notify(void *opaque)
+{
+    CharDriverState *chr = opaque;
+    qemu_chr_event(chr, CHR_EVENT_PPINT);
+}
+
+static void pp_chr_update_read_handler(CharDriverState *chr)
+{
+    ParallelCharDriver *s = chr->opaque;
+
+    if (chr->chr_event == NULL)
+        qemu_set_fd_handler(s->fd, NULL, NULL, NULL);
+    else
+        qemu_set_fd_handler(s->fd, pp_int_notify, NULL, chr);
+}
+
 static void pp_close(CharDriverState *chr)
 {
     ParallelCharDriver *drv = chr->opaque;
     int fd = drv->fd;
 
+    qemu_set_fd_handler(fd, NULL, NULL, NULL);
     pp_hw_mode(drv, IEEE1284_MODE_COMPAT);
     ioctl(fd, PPRELEASE);
     close(fd);
@@ -1278,6 +1305,7 @@
     chr->chr_write = null_chr_write;
     chr->chr_ioctl = pp_ioctl;
     chr->chr_close = pp_close;
+    chr->chr_update_read_handler = pp_chr_update_read_handler;
     chr->opaque = drv;
 
     qemu_chr_reset(chr);