Eepro100 emulation, by Stefan Weil.

git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@2584 c046a42c-6fe2-441c-8c8c-71466251a162

1 files changed, 312 insertions, 0 deletions

diff --git a/hw/eeprom93xx.c b/hw/eeprom93xx.c
new file mode 100644
index 0000000..14f0189
--- /dev/null
+++ b/hw/eeprom93xx.c
@@ -0,0 +1,312 @@
+/*
+ * QEMU EEPROM 93xx emulation
+ *
+ * Copyright (c) 2006-2007 Stefan Weil
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program 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 General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+ */
+
+/* Emulation for serial EEPROMs:
+ * NMC93C06 256-Bit (16 x 16)
+ * NMC93C46 1024-Bit (64 x 16)
+ * NMC93C56 2028 Bit (128 x 16)
+ * NMC93C66 4096 Bit (256 x 16)
+ * Compatible devices include FM93C46 and others.
+ *
+ * Other drivers use these interface functions:
+ * eeprom93xx_new   - add a new EEPROM (with 16, 64 or 256 words)
+ * eeprom93xx_free  - destroy EEPROM
+ * eeprom93xx_read  - read data from the EEPROM
+ * eeprom93xx_write - write data to the EEPROM
+ * eeprom93xx_data  - get EEPROM data array for external manipulation
+ *
+ * Todo list:
+ * - No emulation of EEPROM timings.
+ */
+
+#include <assert.h>
+#include "eeprom93xx.h"
+
+/* Debug EEPROM emulation. */
+//~ #define DEBUG_EEPROM
+
+#ifdef DEBUG_EEPROM
+#define logout(fmt, args...) fprintf(stderr, "EEPROM\t%-24s" fmt, __func__, ##args)
+#else
+#define logout(fmt, args...) ((void)0)
+#endif
+
+static int eeprom_instance = 0;
+static const int eeprom_version = 20061112;
+
+#if 0
+typedef enum {
+  eeprom_read  = 0x80,   /* read register xx */
+  eeprom_write = 0x40,   /* write register xx */
+  eeprom_erase = 0xc0,   /* erase register xx */
+  eeprom_ewen  = 0x30,   /* erase / write enable */
+  eeprom_ewds  = 0x00,   /* erase / write disable */
+  eeprom_eral  = 0x20,   /* erase all registers */
+  eeprom_wral  = 0x10,   /* write all registers */
+  eeprom_amask = 0x0f,
+  eeprom_imask = 0xf0
+} eeprom_instruction_t;
+#endif
+
+#ifdef DEBUG_EEPROM
+static const char *opstring[] = {
+  "extended", "write", "read", "erase"
+};
+#endif
+
+struct _eeprom_t {
+    uint8_t  tick;
+    uint8_t  address;
+    uint8_t  command;
+    uint8_t  writeable;
+
+    uint8_t eecs;
+    uint8_t eesk;
+    uint8_t eedo;
+
+    uint8_t  addrbits;
+    uint8_t  size;
+    uint16_t data;
+    uint16_t contents[0];
+};
+
+/* Code for saving and restoring of EEPROM state. */
+
+static void eeprom_save(QEMUFile *f, void *opaque)
+{
+    /* Save EEPROM data. */
+    unsigned address;
+    eeprom_t *eeprom = (eeprom_t *)opaque;
+    qemu_put_buffer(f, (uint8_t *)eeprom, sizeof(*eeprom) - 2);
+    qemu_put_be16(f, eeprom->data);
+    for (address = 0; address < eeprom->size; address++) {
+        qemu_put_be16(f, eeprom->contents[address]);
+    }
+}
+
+static int eeprom_load(QEMUFile *f, void *opaque, int version_id)
+{
+    /* Load EEPROM data from saved data if version and EEPROM size
+       of data and current EEPROM are identical. */
+    eeprom_t *eeprom = (eeprom_t *)opaque;
+    int result = -EINVAL;
+    if (version_id == eeprom_version) {
+        unsigned address;
+        uint8_t size = eeprom->size;
+        qemu_get_buffer(f, (uint8_t *)eeprom, sizeof(*eeprom) - 2);
+        if (eeprom->size == size) {
+            eeprom->data = qemu_get_be16(f);
+            for (address = 0; address < eeprom->size; address++) {
+                eeprom->contents[address] = qemu_get_be16(f);
+            }
+            result = 0;
+        }
+    }
+    return result;
+}
+
+void eeprom93xx_write(eeprom_t *eeprom, int eecs, int eesk, int eedi)
+{
+    uint8_t tick = eeprom->tick;
+    uint8_t eedo = eeprom->eedo;
+    uint16_t address = eeprom->address;
+    uint8_t command = eeprom->command;
+
+    logout("CS=%u SK=%u DI=%u DO=%u, tick = %u\n",
+           eecs, eesk, eedi, eedo, tick);
+
+    if (! eeprom->eecs && eecs) {
+        /* Start chip select cycle. */
+        logout("Cycle start, waiting for 1st start bit (0)\n");
+        tick = 0;
+        command = 0x0;
+        address = 0x0;
+    } else if (eeprom->eecs && ! eecs) {
+        /* End chip select cycle. This triggers write / erase. */
+        if (eeprom->writeable) {
+            uint8_t subcommand = address >> (eeprom->addrbits - 2);
+            if (command == 0 && subcommand == 2) {
+                /* Erase all. */
+                for (address = 0; address < eeprom->size; address++) {
+                    eeprom->contents[address] = 0xffff;
+                }
+            } else if (command == 3) {
+                /* Erase word. */
+                eeprom->contents[address] = 0xffff;
+            } else if (tick >= 2 + 2 + eeprom->addrbits + 16) {
+                if (command == 1) {
+                    /* Write word. */
+                    eeprom->contents[address] &= eeprom->data;
+                } else if (command == 0 && subcommand == 1) {
+                    /* Write all. */
+                    for (address = 0; address < eeprom->size; address++) {
+                        eeprom->contents[address] &= eeprom->data;
+                    }
+                }
+            }
+        }
+        /* Output DO is tristate, read results in 1. */
+        eedo = 1;
+    } else if (eecs && ! eeprom->eesk && eesk) {
+        /* Raising edge of clock shifts data in. */
+        if (tick == 0) {
+            /* Wait for 1st start bit. */
+            if (eedi == 0) {
+                logout("Got correct 1st start bit, waiting for 2nd start bit (1)\n");
+                tick++;
+            } else {
+                logout("wrong 1st start bit (is 1, should be 0)\n");
+                tick = 2;
+                //~ assert(!"wrong start bit");
+            }
+        } else if (tick == 1) {
+            /* Wait for 2nd start bit. */
+            if (eedi != 0) {
+                logout("Got correct 2nd start bit, getting command + address\n");
+                tick++;
+            } else {
+                logout("1st start bit is longer than needed\n");
+            }
+        } else if (tick < 2 + 2) {
+            /* Got 2 start bits, transfer 2 opcode bits. */
+            tick++;
+            command <<= 1;
+            if (eedi) {
+                command += 1;
+            }
+        } else if (tick < 2 + 2 + eeprom->addrbits) {
+            /* Got 2 start bits and 2 opcode bits, transfer all address bits. */
+            tick++;
+            address = ((address << 1) | eedi);
+            if (tick == 2 + 2 + eeprom->addrbits) {
+                logout("%s command, address = 0x%02x (value 0x%04x)\n",
+                       opstring[command], address, eeprom->contents[address]);
+                if (command == 2) {
+                    eedo = 0;
+                }
+                address = address % eeprom->size;
+                if (command == 0) {
+                    /* Command code in upper 2 bits of address. */
+                    switch (address >> (eeprom->addrbits - 2)) {
+                        case 0:
+                            logout("write disable command\n");
+                            eeprom->writeable = 0;
+                            break;
+                        case 1:
+                            logout("write all command\n");
+                            break;
+                        case 2:
+                            logout("erase all command\n");
+                            break;
+                        case 3:
+                            logout("write enable command\n");
+                            eeprom->writeable = 1;
+                            break;
+                    }
+                } else {
+                    /* Read, write or erase word. */
+                    eeprom->data = eeprom->contents[address];
+                }
+            }
+        } else if (tick < 2 + 2 + eeprom->addrbits + 16) {
+            /* Transfer 16 data bits. */
+            tick++;
+            if (command == 2) {
+                /* Read word. */
+                eedo = ((eeprom->data & 0x8000) != 0);
+            }
+            eeprom->data <<= 1;
+            eeprom->data += eedi;
+        } else {
+            logout("additional unneeded tick, not processed\n");
+        }
+    }
+    /* Save status of EEPROM. */
+    eeprom->tick = tick;
+    eeprom->eecs = eecs;
+    eeprom->eesk = eesk;
+    eeprom->eedo = eedo;
+    eeprom->address = address;
+    eeprom->command = command;
+}
+
+uint16_t eeprom93xx_read(eeprom_t *eeprom)
+{
+    /* Return status of pin DO (0 or 1). */
+    logout("CS=%u DO=%u\n", eeprom->eecs, eeprom->eedo);
+    return (eeprom->eedo);
+}
+
+#if 0
+void eeprom93xx_reset(eeprom_t *eeprom)
+{
+    /* prepare eeprom */
+    logout("eeprom = 0x%p\n", eeprom);
+    eeprom->tick = 0;
+    eeprom->command = 0;
+}
+#endif
+
+eeprom_t *eeprom93xx_new(uint16_t nwords)
+{
+    /* Add a new EEPROM (with 16, 64 or 256 words). */
+    eeprom_t *eeprom;
+    uint8_t addrbits;
+
+    switch (nwords) {
+        case 16:
+        case 64:
+            addrbits = 6;
+            break;
+        case 128:
+        case 256:
+            addrbits = 8;
+            break;
+        default:
+            assert(!"Unsupported EEPROM size, fallback to 64 words!");
+            nwords = 64;
+            addrbits = 6;
+    }
+
+    eeprom = (eeprom_t *)qemu_mallocz(sizeof(*eeprom) + nwords * 2);
+    eeprom->size = nwords;
+    eeprom->addrbits = addrbits;
+    /* Output DO is tristate, read results in 1. */
+    eeprom->eedo = 1;
+    logout("eeprom = 0x%p, nwords = %u\n", eeprom, nwords);
+    register_savevm("eeprom", eeprom_instance, eeprom_version,
+                    eeprom_save, eeprom_load, eeprom);
+    return eeprom;
+}
+
+void eeprom93xx_free(eeprom_t *eeprom)
+{
+    /* Destroy EEPROM. */
+    logout("eeprom = 0x%p\n", eeprom);
+    qemu_free(eeprom);
+}
+
+uint16_t *eeprom93xx_data(eeprom_t *eeprom)
+{
+    /* Get EEPROM data array. */
+    return &eeprom->contents[0];
+}
+
+/* eof */