Implement hcall based RTAS for pSeries machines

On pSeries machines, operating systems can instantiate "RTAS" (Run-Time
Abstraction Services), a runtime component of the firmware which implements
a number of low-level, infrequently used operations.  On logical partitions
under a hypervisor, many of the RTAS functions require hypervisor
privilege.  For simplicity, therefore, hypervisor systems typically
implement the in-partition RTAS as just a tiny wrapper around a hypercall
which actually implements the various RTAS functions.

This patch implements such a hypercall based RTAS for our emulated pSeries
machine.  A tiny in-partition "firmware" calls a new hypercall, which
looks up available RTAS services in a table.

Signed-off-by: David Gibson <dwg@au1.ibm.com>
Signed-off-by: Alexander Graf <agraf@suse.de>

hw/spapr_rtas.c

@@ -0,0 +1,131 @@
+/*
+ * QEMU PowerPC pSeries Logical Partition (aka sPAPR) hardware System Emulator
+ *
+ * Hypercall based emulated RTAS
+ *
+ * Copyright (c) 2010-2011 David Gibson, IBM Corporation.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
+ * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ *
+ */
+#include "cpu.h"
+#include "sysemu.h"
+#include "qemu-char.h"
+#include "hw/qdev.h"
+#include "device_tree.h"
+
+#include "hw/spapr.h"
+#include "hw/spapr_vio.h"
+
+#include <libfdt.h>
+
+#define TOKEN_BASE      0x2000
+#define TOKEN_MAX       0x100
+
+static struct rtas_call {
+    const char *name;
+    spapr_rtas_fn fn;
+} rtas_table[TOKEN_MAX];
+
+struct rtas_call *rtas_next = rtas_table;
+
+target_ulong spapr_rtas_call(sPAPREnvironment *spapr,
+                             uint32_t token, uint32_t nargs, target_ulong args,
+                             uint32_t nret, target_ulong rets)
+{
+    if ((token >= TOKEN_BASE)
+        && ((token - TOKEN_BASE) < TOKEN_MAX)) {
+        struct rtas_call *call = rtas_table + (token - TOKEN_BASE);
+
+        if (call->fn) {
+            call->fn(spapr, token, nargs, args, nret, rets);
+            return H_SUCCESS;
+        }
+    }
+
+    hcall_dprintf("Unknown RTAS token 0x%x\n", token);
+    rtas_st(rets, 0, -3);
+    return H_PARAMETER;
+}
+
+void spapr_rtas_register(const char *name, spapr_rtas_fn fn)
+{
+    assert(rtas_next < (rtas_table + TOKEN_MAX));
+
+    rtas_next->name = name;
+    rtas_next->fn = fn;
+
+    rtas_next++;
+}
+
+int spapr_rtas_device_tree_setup(void *fdt, target_phys_addr_t rtas_addr,
+                                 target_phys_addr_t rtas_size)
+{
+    int ret;
+    int i;
+
+    ret = fdt_add_mem_rsv(fdt, rtas_addr, rtas_size);
+    if (ret < 0) {
+        fprintf(stderr, "Couldn't add RTAS reserve entry: %s\n",
+                fdt_strerror(ret));
+        return ret;
+    }
+
+    ret = qemu_devtree_setprop_cell(fdt, "/rtas", "linux,rtas-base",
+                                    rtas_addr);
+    if (ret < 0) {
+        fprintf(stderr, "Couldn't add linux,rtas-base property: %s\n",
+                fdt_strerror(ret));
+        return ret;
+    }
+
+    ret = qemu_devtree_setprop_cell(fdt, "/rtas", "linux,rtas-entry",
+                                    rtas_addr);
+    if (ret < 0) {
+        fprintf(stderr, "Couldn't add linux,rtas-entry property: %s\n",
+                fdt_strerror(ret));
+        return ret;
+    }
+
+    ret = qemu_devtree_setprop_cell(fdt, "/rtas", "rtas-size",
+                                    rtas_size);
+    if (ret < 0) {
+        fprintf(stderr, "Couldn't add rtas-size property: %s\n",
+                fdt_strerror(ret));
+        return ret;
+    }
+
+    for (i = 0; i < TOKEN_MAX; i++) {
+        struct rtas_call *call = &rtas_table[i];
+
+        if (!call->fn) {
+            continue;
+        }
+
+        ret = qemu_devtree_setprop_cell(fdt, "/rtas", call->name,
+                                        i + TOKEN_BASE);
+        if (ret < 0) {
+            fprintf(stderr, "Couldn't add rtas token for %s: %s\n",
+                    call->name, fdt_strerror(ret));
+            return ret;
+        }
+
+    }
+    return 0;
+}