commit 7673fd2cd207de3774cbf2e0bea9f1f99bab7c87
author Miodrag Dinic <miodrag.dinic@imgtec.com> Tue Jun 16 17:24:06 2015 +0200
committer Miodrag Dinic <miodrag.dinic@imgtec.com> Tue Jun 23 12:31:10 2015 +0200
tree 51a6507d255f560acbbf0ddd8c20a69078ea6900
parent 5e29087a9444d323bbab1ed7c7120ea7ef3739f2

goldfish_tty.c: Use physical addresses instead of virtual

Re-implement Goldfish TTY device to work directly with
physical addresses instead of virtual. Main idea behind
this approach is to move away from using

cpu_memory_rw_debug() -> cpu_phys_page_debug() path

for VA-PA translation, which does not guarantee that it
will return a valid mapping. Using physical addresses
is the correct way to go, ensures less overhead and
faster serial communication.

Change-Id: Ib31f3cb33ac6630816f901a39834c87188ac09aa

hw/char/goldfish_tty.c

diff --git a/hw/char/goldfish_tty.c b/hw/char/goldfish_tty.c
index 5525e3f..7223c60 100644
--- a/hw/char/goldfish_tty.c
+++ b/hw/char/goldfish_tty.c
@@ -17,6 +17,8 @@
 #include "hw/sysbus.h"
 #include "sysemu/sysemu.h"
 
+#define TTY_DEVICE_VERSION 1
+
 enum {
     TTY_PUT_CHAR       = 0x00,
     TTY_BYTES_READY    = 0x04,
@@ -26,6 +28,8 @@
     TTY_DATA_LEN       = 0x14,
     TTY_DATA_PTR_HIGH  = 0x18,
 
+    TTY_VERSION        = 0x20,
+
     TTY_CMD_INT_DISABLE    = 0,
     TTY_CMD_INT_ENABLE     = 1,
     TTY_CMD_WRITE_BUFFER   = 2,
@@ -96,6 +100,8 @@
     switch (offset) {
         case TTY_BYTES_READY:
             return s->data_count;
+        case TTY_VERSION:
+            return TTY_DEVICE_VERSION;
     default:
         cpu_abort(current_cpu,
                   "goldfish_tty_read: Bad offset %" HWADDR_PRIx "\n",
@@ -104,7 +110,8 @@
     }
 }
 
-static void goldfish_tty_write(void *opaque, hwaddr offset, uint64_t value, unsigned size)
+static void goldfish_tty_write(void *opaque, hwaddr offset,
+                               uint64_t value, unsigned size)
 {
     struct tty_state *s = (struct tty_state *)opaque;
 
@@ -135,39 +142,42 @@
 
                 case TTY_CMD_WRITE_BUFFER:
                     if(s->cs) {
-                        int len;
-                        target_ulong  buf;
+                        hwaddr l = s->ptr_len;
+                        void *ptr;
 
-                        buf = s->ptr;
-                        len = s->ptr_len;
-
-                        while (len) {
-                            char   temp[64];
-                            int    to_write = sizeof(temp);
-                            if (to_write > len)
-                                to_write = len;
-
-                            cpu_memory_rw_debug(current_cpu, buf, (uint8_t*)temp, to_write, 0);
-                            qemu_chr_fe_write(s->cs, (const uint8_t*)temp, to_write);
-                            buf += to_write;
-                            len -= to_write;
-                        }
+                        ptr = cpu_physical_memory_map(s->ptr, &l, 0);
+                        qemu_chr_fe_write(s->cs, (const uint8_t*)ptr, l);
+                        cpu_physical_memory_unmap(ptr, l, 0, 0);
                     }
                     break;
 
                 case TTY_CMD_READ_BUFFER:
-                    if(s->ptr_len > s->data_count)
-                        cpu_abort(current_cpu, "goldfish_tty_write: reading more data than available %d %d\n", s->ptr_len, s->data_count);
-                    cpu_memory_rw_debug(current_cpu, s->ptr, s->data, s->ptr_len,1);
-                    if(s->data_count > s->ptr_len)
-                        memmove(s->data, s->data + s->ptr_len, s->data_count - s->ptr_len);
-                    s->data_count -= s->ptr_len;
-                    if(s->data_count == 0 && s->ready)
-                        qemu_set_irq(s->irq, 0);
+                    {
+                        hwaddr l = s->ptr_len;
+                        void *ptr;
+
+                        if(s->ptr_len > s->data_count)
+                            cpu_abort(current_cpu,
+                                      "goldfish_tty_write: reading"
+                                      " more data than available %d %d\n",
+                                      s->ptr_len, s->data_count);
+
+                        ptr = cpu_physical_memory_map(s->ptr, &l, 1);
+                        memcpy(ptr, s->data, l);
+                        cpu_physical_memory_unmap(ptr, l, 1, l);
+
+                        if(s->data_count > l)
+                            memmove(s->data, s->data + l, s->data_count - l);
+                        s->data_count -= l;
+                        if(s->data_count == 0 && s->ready)
+                            qemu_set_irq(s->irq, 0);
+                    }
                     break;
 
                 default:
-                    cpu_abort(current_cpu, "goldfish_tty_write: Bad command %" PRIx64 "\n", value);
+                    cpu_abort(current_cpu,
+                              "goldfish_tty_write: Bad command %" PRIx64 "\n",
+                              value);
             };
             break;
 
@@ -224,7 +234,9 @@
     int i;
 
     if ((instance_id + 1) == MAX_SERIAL_PORTS) {
-        cpu_abort(current_cpu, "goldfish_tty: MAX_SERIAL_PORTS(%d) reached\n", MAX_SERIAL_PORTS);
+        cpu_abort(current_cpu,
+                  "goldfish_tty: MAX_SERIAL_PORTS(%d) reached\n",
+                  MAX_SERIAL_PORTS);
     }
 
     memory_region_init_io(&s->iomem, OBJECT(s), &mips_qemu_ops, s,
@@ -235,7 +247,8 @@
     for(i = 0; i < MAX_SERIAL_PORTS; i++) {
         if(serial_hds[i]) {
             s->cs = serial_hds[i];
-            qemu_chr_add_handlers(serial_hds[i], tty_can_receive, tty_receive, NULL, s);
+            qemu_chr_add_handlers(serial_hds[i], tty_can_receive,
+                                  tty_receive, NULL, s);
             break;
         }
     }