nios2: Add architecture emulation support

Add support for emulating Altera NiosII R1 architecture into qemu.
This patch is based on previous work by Chris Wulff from 2012 and
updated to latest mainline QEMU.

Signed-off-by: Marek Vasut <marex@denx.de>
Cc: Chris Wulff <crwulff@gmail.com>
Cc: Jeff Da Silva <jdasilva@altera.com>
Cc: Ley Foon Tan <lftan@altera.com>
Cc: Sandra Loosemore <sandra@codesourcery.com>
Cc: Yves Vandervennet <yvanderv@altera.com>
Cc: Alexander Graf <agraf@suse.de>
Message-Id: <20170118220146.489-3-marex@denx.de>
[rth: Remove tlb_flush from nios2_cpu_reset.]
Signed-off-by: Richard Henderson <rth@twiddle.net>

1 files changed, 296 insertions, 0 deletions

diff --git a/target/nios2/mmu.c b/target/nios2/mmu.c
new file mode 100644
index 0000000000..fe9298af50
--- /dev/null
+++ b/target/nios2/mmu.c
@@ -0,0 +1,296 @@
+/*
+ * Altera Nios II MMU emulation for qemu.
+ *
+ * Copyright (C) 2012 Chris Wulff <crwulff@gmail.com>
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, see
+ * <http://www.gnu.org/licenses/lgpl-2.1.html>
+ */
+
+#include "qemu/osdep.h"
+#include "qemu-common.h"
+#include "cpu.h"
+#include "exec/exec-all.h"
+#include "mmu.h"
+
+#if !defined(CONFIG_USER_ONLY)
+
+/* Define this to enable MMU debug messages */
+/* #define DEBUG_MMU */
+
+#ifdef DEBUG_MMU
+#define MMU_LOG(x) x
+#else
+#define MMU_LOG(x)
+#endif
+
+void tlb_fill(CPUState *cs, target_ulong addr, MMUAccessType access_type,
+              int mmu_idx, uintptr_t retaddr)
+{
+    int ret;
+
+    ret = nios2_cpu_handle_mmu_fault(cs, addr, access_type, mmu_idx);
+    if (unlikely(ret)) {
+        if (retaddr) {
+            /* now we have a real cpu fault */
+            cpu_restore_state(cs, retaddr);
+        }
+        cpu_loop_exit(cs);
+    }
+}
+
+void mmu_read_debug(CPUNios2State *env, uint32_t rn)
+{
+    switch (rn) {
+    case CR_TLBACC:
+        MMU_LOG(qemu_log("TLBACC READ %08X\n", env->regs[rn]));
+        break;
+
+    case CR_TLBMISC:
+        MMU_LOG(qemu_log("TLBMISC READ %08X\n", env->regs[rn]));
+        break;
+
+    case CR_PTEADDR:
+        MMU_LOG(qemu_log("PTEADDR READ %08X\n", env->regs[rn]));
+        break;
+
+    default:
+        break;
+    }
+}
+
+/* rw - 0 = read, 1 = write, 2 = fetch.  */
+unsigned int mmu_translate(CPUNios2State *env,
+                           Nios2MMULookup *lu,
+                           target_ulong vaddr, int rw, int mmu_idx)
+{
+    Nios2CPU *cpu = nios2_env_get_cpu(env);
+    int pid = (env->mmu.tlbmisc_wr & CR_TLBMISC_PID_MASK) >> 4;
+    int vpn = vaddr >> 12;
+
+    MMU_LOG(qemu_log("mmu_translate vaddr %08X, pid %08X, vpn %08X\n",
+                     vaddr, pid, vpn));
+
+    int way;
+    for (way = 0; way < cpu->tlb_num_ways; way++) {
+
+        Nios2TLBEntry *entry =
+            &env->mmu.tlb[(way * cpu->tlb_num_ways) +
+                          (vpn & env->mmu.tlb_entry_mask)];
+
+        MMU_LOG(qemu_log("TLB[%d] TAG %08X, VPN %08X\n",
+                         (way * cpu->tlb_num_ways) +
+                         (vpn & env->mmu.tlb_entry_mask),
+                         entry->tag, (entry->tag >> 12)));
+
+        if (((entry->tag >> 12) != vpn) ||
+            (((entry->tag & (1 << 11)) == 0) &&
+            ((entry->tag & ((1 << cpu->pid_num_bits) - 1)) != pid))) {
+            continue;
+        }
+        lu->vaddr = vaddr & TARGET_PAGE_MASK;
+        lu->paddr = (entry->data & CR_TLBACC_PFN_MASK) << TARGET_PAGE_BITS;
+        lu->prot = ((entry->data & CR_TLBACC_R) ? PAGE_READ : 0) |
+                   ((entry->data & CR_TLBACC_W) ? PAGE_WRITE : 0) |
+                   ((entry->data & CR_TLBACC_X) ? PAGE_EXEC : 0);
+
+        MMU_LOG(qemu_log("HIT TLB[%d] %08X %08X %08X\n",
+                         (way * cpu->tlb_num_ways) +
+                         (vpn & env->mmu.tlb_entry_mask),
+                         lu->vaddr, lu->paddr, lu->prot));
+        return 1;
+    }
+    return 0;
+}
+
+static void mmu_flush_pid(CPUNios2State *env, uint32_t pid)
+{
+    CPUState *cs = ENV_GET_CPU(env);
+    Nios2CPU *cpu = nios2_env_get_cpu(env);
+    int idx;
+    MMU_LOG(qemu_log("TLB Flush PID %d\n", pid));
+
+    for (idx = 0; idx < cpu->tlb_num_entries; idx++) {
+        Nios2TLBEntry *entry = &env->mmu.tlb[idx];
+
+        MMU_LOG(qemu_log("TLB[%d] => %08X %08X\n",
+                         idx, entry->tag, entry->data));
+
+        if ((entry->tag & (1 << 10)) && (!(entry->tag & (1 << 11))) &&
+            ((entry->tag & ((1 << cpu->pid_num_bits) - 1)) == pid)) {
+            uint32_t vaddr = entry->tag & TARGET_PAGE_MASK;
+
+            MMU_LOG(qemu_log("TLB Flush Page %08X\n", vaddr));
+
+            tlb_flush_page(cs, vaddr);
+        }
+    }
+}
+
+void mmu_write(CPUNios2State *env, uint32_t rn, uint32_t v)
+{
+    CPUState *cs = ENV_GET_CPU(env);
+    Nios2CPU *cpu = nios2_env_get_cpu(env);
+
+    MMU_LOG(qemu_log("mmu_write %08X = %08X\n", rn, v));
+
+    switch (rn) {
+    case CR_TLBACC:
+        MMU_LOG(qemu_log("TLBACC: IG %02X, FLAGS %c%c%c%c%c, PFN %05X\n",
+                         v >> CR_TLBACC_IGN_SHIFT,
+                         (v & CR_TLBACC_C) ? 'C' : '.',
+                         (v & CR_TLBACC_R) ? 'R' : '.',
+                         (v & CR_TLBACC_W) ? 'W' : '.',
+                         (v & CR_TLBACC_X) ? 'X' : '.',
+                         (v & CR_TLBACC_G) ? 'G' : '.',
+                         v & CR_TLBACC_PFN_MASK));
+
+        /* if tlbmisc.WE == 1 then trigger a TLB write on writes to TLBACC */
+        if (env->regs[CR_TLBMISC] & CR_TLBMISC_WR) {
+            int way = (env->regs[CR_TLBMISC] >> CR_TLBMISC_WAY_SHIFT);
+            int vpn = (env->mmu.pteaddr_wr & CR_PTEADDR_VPN_MASK) >> 2;
+            int pid = (env->mmu.tlbmisc_wr & CR_TLBMISC_PID_MASK) >> 4;
+            int g = (v & CR_TLBACC_G) ? 1 : 0;
+            int valid = ((vpn & CR_TLBACC_PFN_MASK) < 0xC0000) ? 1 : 0;
+            Nios2TLBEntry *entry =
+                &env->mmu.tlb[(way * cpu->tlb_num_ways) +
+                              (vpn & env->mmu.tlb_entry_mask)];
+            uint32_t newTag = (vpn << 12) | (g << 11) | (valid << 10) | pid;
+            uint32_t newData = v & (CR_TLBACC_C | CR_TLBACC_R | CR_TLBACC_W |
+                                    CR_TLBACC_X | CR_TLBACC_PFN_MASK);
+
+            if ((entry->tag != newTag) || (entry->data != newData)) {
+                if (entry->tag & (1 << 10)) {
+                    /* Flush existing entry */
+                    MMU_LOG(qemu_log("TLB Flush Page (OLD) %08X\n",
+                                     entry->tag & TARGET_PAGE_MASK));
+                    tlb_flush_page(cs, entry->tag & TARGET_PAGE_MASK);
+                }
+                entry->tag = newTag;
+                entry->data = newData;
+                MMU_LOG(qemu_log("TLB[%d] = %08X %08X\n",
+                                 (way * cpu->tlb_num_ways) +
+                                 (vpn & env->mmu.tlb_entry_mask),
+                                 entry->tag, entry->data));
+            }
+            /* Auto-increment tlbmisc.WAY */
+            env->regs[CR_TLBMISC] =
+                (env->regs[CR_TLBMISC] & ~CR_TLBMISC_WAY_MASK) |
+                (((way + 1) & (cpu->tlb_num_ways - 1)) <<
+                 CR_TLBMISC_WAY_SHIFT);
+        }
+
+        /* Writes to TLBACC don't change the read-back value */
+        env->mmu.tlbacc_wr = v;
+        break;
+
+    case CR_TLBMISC:
+        MMU_LOG(qemu_log("TLBMISC: WAY %X, FLAGS %c%c%c%c%c%c, PID %04X\n",
+                         v >> CR_TLBMISC_WAY_SHIFT,
+                         (v & CR_TLBMISC_RD) ? 'R' : '.',
+                         (v & CR_TLBMISC_WR) ? 'W' : '.',
+                         (v & CR_TLBMISC_DBL) ? '2' : '.',
+                         (v & CR_TLBMISC_BAD) ? 'B' : '.',
+                         (v & CR_TLBMISC_PERM) ? 'P' : '.',
+                         (v & CR_TLBMISC_D) ? 'D' : '.',
+                         (v & CR_TLBMISC_PID_MASK) >> 4));
+
+        if ((v & CR_TLBMISC_PID_MASK) !=
+            (env->mmu.tlbmisc_wr & CR_TLBMISC_PID_MASK)) {
+            mmu_flush_pid(env, (env->mmu.tlbmisc_wr & CR_TLBMISC_PID_MASK) >>
+                               CR_TLBMISC_PID_SHIFT);
+        }
+        /* if tlbmisc.RD == 1 then trigger a TLB read on writes to TLBMISC */
+        if (v & CR_TLBMISC_RD) {
+            int way = (v >> CR_TLBMISC_WAY_SHIFT);
+            int vpn = (env->mmu.pteaddr_wr & CR_PTEADDR_VPN_MASK) >> 2;
+            Nios2TLBEntry *entry =
+                &env->mmu.tlb[(way * cpu->tlb_num_ways) +
+                              (vpn & env->mmu.tlb_entry_mask)];
+
+            env->regs[CR_TLBACC] &= CR_TLBACC_IGN_MASK;
+            env->regs[CR_TLBACC] |= entry->data;
+            env->regs[CR_TLBACC] |= (entry->tag & (1 << 11)) ? CR_TLBACC_G : 0;
+            env->regs[CR_TLBMISC] =
+                (v & ~CR_TLBMISC_PID_MASK) |
+                ((entry->tag & ((1 << cpu->pid_num_bits) - 1)) <<
+                 CR_TLBMISC_PID_SHIFT);
+            env->regs[CR_PTEADDR] &= ~CR_PTEADDR_VPN_MASK;
+            env->regs[CR_PTEADDR] |= (entry->tag >> 12) << CR_PTEADDR_VPN_SHIFT;
+            MMU_LOG(qemu_log("TLB READ way %d, vpn %05X, tag %08X, data %08X, "
+                             "tlbacc %08X, tlbmisc %08X, pteaddr %08X\n",
+                             way, vpn, entry->tag, entry->data,
+                             env->regs[CR_TLBACC], env->regs[CR_TLBMISC],
+                             env->regs[CR_PTEADDR]));
+        } else {
+            env->regs[CR_TLBMISC] = v;
+        }
+
+        env->mmu.tlbmisc_wr = v;
+        break;
+
+    case CR_PTEADDR:
+        MMU_LOG(qemu_log("PTEADDR: PTBASE %03X, VPN %05X\n",
+                         v >> CR_PTEADDR_PTBASE_SHIFT,
+                         (v & CR_PTEADDR_VPN_MASK) >> CR_PTEADDR_VPN_SHIFT));
+
+        /* Writes to PTEADDR don't change the read-back VPN value */
+        env->regs[CR_PTEADDR] = (v & ~CR_PTEADDR_VPN_MASK) |
+                                (env->regs[CR_PTEADDR] & CR_PTEADDR_VPN_MASK);
+        env->mmu.pteaddr_wr = v;
+        break;
+
+    default:
+        break;
+    }
+}
+
+void mmu_init(CPUNios2State *env)
+{
+    Nios2CPU *cpu = nios2_env_get_cpu(env);
+    Nios2MMU *mmu = &env->mmu;
+
+    MMU_LOG(qemu_log("mmu_init\n"));
+
+    mmu->tlb_entry_mask = (cpu->tlb_num_entries / cpu->tlb_num_ways) - 1;
+    mmu->tlb = g_new0(Nios2TLBEntry, cpu->tlb_num_entries);
+}
+
+void dump_mmu(FILE *f, fprintf_function cpu_fprintf, CPUNios2State *env)
+{
+    Nios2CPU *cpu = nios2_env_get_cpu(env);
+    int i;
+
+    cpu_fprintf(f, "MMU: ways %d, entries %d, pid bits %d\n",
+                cpu->tlb_num_ways, cpu->tlb_num_entries,
+                cpu->pid_num_bits);
+
+    for (i = 0; i < cpu->tlb_num_entries; i++) {
+        Nios2TLBEntry *entry = &env->mmu.tlb[i];
+        cpu_fprintf(f, "TLB[%d] = %08X %08X %c VPN %05X "
+                    "PID %02X %c PFN %05X %c%c%c%c\n",
+                    i, entry->tag, entry->data,
+                    (entry->tag & (1 << 10)) ? 'V' : '-',
+                    entry->tag >> 12,
+                    entry->tag & ((1 << cpu->pid_num_bits) - 1),
+                    (entry->tag & (1 << 11)) ? 'G' : '-',
+                    entry->data & CR_TLBACC_PFN_MASK,
+                    (entry->data & CR_TLBACC_C) ? 'C' : '-',
+                    (entry->data & CR_TLBACC_R) ? 'R' : '-',
+                    (entry->data & CR_TLBACC_W) ? 'W' : '-',
+                    (entry->data & CR_TLBACC_X) ? 'X' : '-');
+    }
+}
+
+#endif /* !CONFIG_USER_ONLY */