[patch] HVSI udbg

[Hollis Blanchard]

This fixes a long-standing omission in HVSI support: dropping to xmon would 
basically hang your system, as there was no udbg code to read/write chars 
from xmon. It's based on the existing "LP" routines.

Could we get this pushed upstream soon?

-- 
Hollis Blanchard
IBM Linux Technology Center

===== arch/ppc64/kernel/pSeries_lpar.c 1.41 vs edited =====
--- 1.41/arch/ppc64/kernel/pSeries_lpar.c Tue Sep 21 23:40:30 2004
+++ edited/arch/ppc64/kernel/pSeries_lpar.c Thu Oct  7 10:52:23 2004
@@ -59,6 +59,74 @@
 
 int vtermno; /* virtual terminal# for udbg  */
 
+#define __ALIGNED__ __attribute__((__aligned__(sizeof(long))))
+static void udbg_hvsi_putc(unsigned char c)
+{
+ /* packet's seqno isn't used anyways */
+ uint8_t packet[] __ALIGNED__ = { 0xff, 5, 0, 0, c };
+ int rc;
+
+ if (c == '\n')
+  udbg_hvsi_putc('\r');
+
+ do {
+  rc = plpar_put_term_char(vtermno, sizeof(packet), packet);
+ } while (rc == H_Busy);
+}
+
+static long hvsi_udbg_buf_len;
+static uint8_t hvsi_udbg_buf[256];
+
+static int udbg_hvsi_getc_poll(void)
+{
+ unsigned char ch;
+ int rc, i;
+
+ if (hvsi_udbg_buf_len == 0) {
+  rc = plpar_get_term_char(vtermno, &hvsi_udbg_buf_len, hvsi_udbg_buf);
+  if (rc != H_Success || hvsi_udbg_buf[0] != 0xff) {
+   /* bad read or non-data packet */
+   hvsi_udbg_buf_len = 0;
+  } else {
+   /* remove the packet header */
+   for (i = 4; i < hvsi_udbg_buf_len; i++)
+    hvsi_udbg_buf[i-4] = hvsi_udbg_buf[i];
+   hvsi_udbg_buf_len -= 4;
+  }
+ }
+
+ if (hvsi_udbg_buf_len <= 0 || hvsi_udbg_buf_len > 256) {
+  /* no data ready */
+  hvsi_udbg_buf_len = 0;
+  return -1;
+ }
+
+ ch = hvsi_udbg_buf[0];
+ /* shift remaining data down */
+ for (i = 1; i < hvsi_udbg_buf_len; i++) {
+  hvsi_udbg_buf[i-1] = hvsi_udbg_buf[i];
+ }
+ hvsi_udbg_buf_len--;
+
+ return ch;
+}
+
+static unsigned char udbg_hvsi_getc(void)
+{
+ int ch;
+ for (;;) {
+  ch = udbg_hvsi_getc_poll();
+  if (ch == -1) {
+   /* This shouldn't be needed...but... */
+   volatile unsigned long delay;
+   for (delay=0; delay < 2000000; delay++)
+    ;
+  } else {
+   return ch;
+  }
+ }
+}
+
 static void udbg_putcLP(unsigned char c)
 {
  char buf[16];
@@ -167,11 +235,15 @@
     ppc_md.udbg_getc_poll = udbg_getc_pollLP;
     found = 1;
    }
-  } else {
-   /* XXX implement udbg_putcLP_vtty for hvterm-protocol1 case */
-   printk(KERN_WARNING "%s doesn't speak hvterm1; "
-     "can't print udbg messages\n",
-          stdout_node->full_name);
+  } else if (device_is_compatible(stdout_node, "hvterm-protocol")) {
+   termno = (u32 *)get_property(stdout_node, "reg", NULL);
+   if (termno) {
+    vtermno = termno[0];
+    ppc_md.udbg_putc = udbg_hvsi_putc;
+    ppc_md.udbg_getc = udbg_hvsi_getc;
+    ppc_md.udbg_getc_poll = udbg_hvsi_getc_poll;
+    found = 1;
+   }
   }
  } else if (strncmp(name, "serial", 6)) {
   /* XXX fix ISA serial console */