[qemu.git] / hw / eeprom93xx.c

/*
 * 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 */
Commit	Line	Data
663e8e51 TS	1	/*
	2	* QEMU EEPROM 93xx emulation
	3	*
	4	* Copyright (c) 2006-2007 Stefan Weil
	5	*
	6	* This program is free software; you can redistribute it and/or modify
	7	* it under the terms of the GNU General Public License as published by
	8	* the Free Software Foundation; either version 2 of the License, or
	9	* (at your option) any later version.
	10	*
	11	* This program is distributed in the hope that it will be useful,
	12	* but WITHOUT ANY WARRANTY; without even the implied warranty of
	13	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	14	* GNU General Public License for more details.
	15	*
	16	* You should have received a copy of the GNU General Public License
	17	* along with this program; if not, write to the Free Software
	18	* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
	19	*/
	20
	21	/* Emulation for serial EEPROMs:
	22	* NMC93C06 256-Bit (16 x 16)
	23	* NMC93C46 1024-Bit (64 x 16)
	24	* NMC93C56 2028 Bit (128 x 16)
	25	* NMC93C66 4096 Bit (256 x 16)
	26	* Compatible devices include FM93C46 and others.
	27	*
	28	* Other drivers use these interface functions:
	29	* eeprom93xx_new - add a new EEPROM (with 16, 64 or 256 words)
	30	* eeprom93xx_free - destroy EEPROM
	31	* eeprom93xx_read - read data from the EEPROM
	32	* eeprom93xx_write - write data to the EEPROM
	33	* eeprom93xx_data - get EEPROM data array for external manipulation
	34	*
	35	* Todo list:
	36	* - No emulation of EEPROM timings.
	37	*/
	38
	39	#include <assert.h>
	40	#include "eeprom93xx.h"
	41
	42	/* Debug EEPROM emulation. */
	43	//~ #define DEBUG_EEPROM
	44
	45	#ifdef DEBUG_EEPROM
	46	#define logout(fmt, args...) fprintf(stderr, "EEPROM\t%-24s" fmt, __func__, ##args)
	47	#else
	48	#define logout(fmt, args...) ((void)0)
	49	#endif
	50
	51	static int eeprom_instance = 0;
	52	static const int eeprom_version = 20061112;
	53
	54	#if 0
	55	typedef enum {
	56	eeprom_read = 0x80, /* read register xx */
	57	eeprom_write = 0x40, /* write register xx */
	58	eeprom_erase = 0xc0, /* erase register xx */
	59	eeprom_ewen = 0x30, /* erase / write enable */
	60	eeprom_ewds = 0x00, /* erase / write disable */
	61	eeprom_eral = 0x20, /* erase all registers */
	62	eeprom_wral = 0x10, /* write all registers */
	63	eeprom_amask = 0x0f,
	64	eeprom_imask = 0xf0
65	} eeprom_instruction_t;
66	#endif
67
68	#ifdef DEBUG_EEPROM
69	static const char *opstring[] = {
70	"extended", "write", "read", "erase"
71	};
72	#endif
73
74	struct _eeprom_t {
75	uint8_t tick;
76	uint8_t address;
77	uint8_t command;
78	uint8_t writeable;
79
80	uint8_t eecs;
81	uint8_t eesk;
82	uint8_t eedo;
83
84	uint8_t addrbits;
85	uint8_t size;
86	uint16_t data;
87	uint16_t contents[0];
88	};
89
90	/* Code for saving and restoring of EEPROM state. */
91
92	static void eeprom_save(QEMUFile f, void opaque)
93	{
94	/* Save EEPROM data. */
95	unsigned address;
96	eeprom_t eeprom = (eeprom_t )opaque;
97	qemu_put_buffer(f, (uint8_t )eeprom, sizeof(eeprom) - 2);
98	qemu_put_be16(f, eeprom->data);
99	for (address = 0; address < eeprom->size; address++) {
100	qemu_put_be16(f, eeprom->contents[address]);
101	}
102	}
103
104	static int eeprom_load(QEMUFile f, void opaque, int version_id)
105	{
106	/* Load EEPROM data from saved data if version and EEPROM size
107	of data and current EEPROM are identical. */
108	eeprom_t eeprom = (eeprom_t )opaque;
109	int result = -EINVAL;
110	if (version_id == eeprom_version) {
111	unsigned address;
112	uint8_t size = eeprom->size;
113	qemu_get_buffer(f, (uint8_t )eeprom, sizeof(eeprom) - 2);
114	if (eeprom->size == size) {
115	eeprom->data = qemu_get_be16(f);
116	for (address = 0; address < eeprom->size; address++) {
117	eeprom->contents[address] = qemu_get_be16(f);
118	}
119	result = 0;
120	}
121	}
122	return result;
123	}
124
125	void eeprom93xx_write(eeprom_t *eeprom, int eecs, int eesk, int eedi)
126	{
127	uint8_t tick = eeprom->tick;
128	uint8_t eedo = eeprom->eedo;
129	uint16_t address = eeprom->address;
130	uint8_t command = eeprom->command;
131
132	logout("CS=%u SK=%u DI=%u DO=%u, tick = %u\n",
133	eecs, eesk, eedi, eedo, tick);
134
135	if (! eeprom->eecs && eecs) {
136	/* Start chip select cycle. */
137	logout("Cycle start, waiting for 1st start bit (0)\n");
138	tick = 0;
139	command = 0x0;
140	address = 0x0;
141	} else if (eeprom->eecs && ! eecs) {
142	/* End chip select cycle. This triggers write / erase. */
143	if (eeprom->writeable) {
144	uint8_t subcommand = address >> (eeprom->addrbits - 2);
145	if (command == 0 && subcommand == 2) {
146	/* Erase all. */
147	for (address = 0; address < eeprom->size; address++) {
148	eeprom->contents[address] = 0xffff;
149	}
150	} else if (command == 3) {
151	/* Erase word. */
152	eeprom->contents[address] = 0xffff;
153	} else if (tick >= 2 + 2 + eeprom->addrbits + 16) {
154	if (command == 1) {
155	/* Write word. */
156	eeprom->contents[address] &= eeprom->data;
157	} else if (command == 0 && subcommand == 1) {
158	/* Write all. */
159	for (address = 0; address < eeprom->size; address++) {
160	eeprom->contents[address] &= eeprom->data;
161	}
162	}
163	}
164	}
165	/* Output DO is tristate, read results in 1. */
166	eedo = 1;
167	} else if (eecs && ! eeprom->eesk && eesk) {
168	/* Raising edge of clock shifts data in. */
169	if (tick == 0) {
170	/* Wait for 1st start bit. */
171	if (eedi == 0) {
172	logout("Got correct 1st start bit, waiting for 2nd start bit (1)\n");
173	tick++;
174	} else {
175	logout("wrong 1st start bit (is 1, should be 0)\n");
176	tick = 2;
177	//~ assert(!"wrong start bit");
178	}
179	} else if (tick == 1) {
180	/* Wait for 2nd start bit. */
181	if (eedi != 0) {
182	logout("Got correct 2nd start bit, getting command + address\n");
183	tick++;
184	} else {
185	logout("1st start bit is longer than needed\n");
186	}
187	} else if (tick < 2 + 2) {
188	/* Got 2 start bits, transfer 2 opcode bits. */
189	tick++;
190	command <<= 1;
191	if (eedi) {
192	command += 1;
193	}
194	} else if (tick < 2 + 2 + eeprom->addrbits) {
195	/* Got 2 start bits and 2 opcode bits, transfer all address bits. */
196	tick++;
197	address = ((address << 1) \| eedi);
198	if (tick == 2 + 2 + eeprom->addrbits) {
199	logout("%s command, address = 0x%02x (value 0x%04x)\n",
200	opstring[command], address, eeprom->contents[address]);
201	if (command == 2) {
202	eedo = 0;
203	}
204	address = address % eeprom->size;
205	if (command == 0) {
206	/* Command code in upper 2 bits of address. */
207	switch (address >> (eeprom->addrbits - 2)) {
208	case 0:
209	logout("write disable command\n");
210	eeprom->writeable = 0;
211	break;
212	case 1:
213	logout("write all command\n");
214	break;
215	case 2:
216	logout("erase all command\n");
217	break;
218	case 3:
219	logout("write enable command\n");
220	eeprom->writeable = 1;
221	break;
222	}
223	} else {
224	/* Read, write or erase word. */
225	eeprom->data = eeprom->contents[address];
226	}
227	}
228	} else if (tick < 2 + 2 + eeprom->addrbits + 16) {
229	/* Transfer 16 data bits. */
230	tick++;
231	if (command == 2) {
232	/* Read word. */
233	eedo = ((eeprom->data & 0x8000) != 0);
234	}
235	eeprom->data <<= 1;
236	eeprom->data += eedi;
237	} else {
238	logout("additional unneeded tick, not processed\n");
239	}
240	}
241	/* Save status of EEPROM. */
242	eeprom->tick = tick;
243	eeprom->eecs = eecs;
244	eeprom->eesk = eesk;
245	eeprom->eedo = eedo;
246	eeprom->address = address;
247	eeprom->command = command;
248	}
249
250	uint16_t eeprom93xx_read(eeprom_t *eeprom)
251	{
252	/* Return status of pin DO (0 or 1). */
253	logout("CS=%u DO=%u\n", eeprom->eecs, eeprom->eedo);
254	return (eeprom->eedo);
255	}
256
257	#if 0
258	void eeprom93xx_reset(eeprom_t *eeprom)
259	{
260	/* prepare eeprom */
261	logout("eeprom = 0x%p\n", eeprom);
262	eeprom->tick = 0;
263	eeprom->command = 0;
264	}
265	#endif
266
267	eeprom_t *eeprom93xx_new(uint16_t nwords)
268	{
269	/* Add a new EEPROM (with 16, 64 or 256 words). */
270	eeprom_t *eeprom;
271	uint8_t addrbits;
272
273	switch (nwords) {
274	case 16:
275	case 64:
276	addrbits = 6;
277	break;
278	case 128:
279	case 256:
280	addrbits = 8;
281	break;
282	default:
283	assert(!"Unsupported EEPROM size, fallback to 64 words!");
284	nwords = 64;
285	addrbits = 6;
286	}
287
288	eeprom = (eeprom_t )qemu_mallocz(sizeof(eeprom) + nwords * 2);
289	eeprom->size = nwords;
290	eeprom->addrbits = addrbits;
291	/* Output DO is tristate, read results in 1. */
292	eeprom->eedo = 1;
293	logout("eeprom = 0x%p, nwords = %u\n", eeprom, nwords);
294	register_savevm("eeprom", eeprom_instance, eeprom_version,
295	eeprom_save, eeprom_load, eeprom);
296	return eeprom;
297	}
298
299	void eeprom93xx_free(eeprom_t *eeprom)
300	{
301	/* Destroy EEPROM. */
302	logout("eeprom = 0x%p\n", eeprom);
303	qemu_free(eeprom);
304	}
305
306	uint16_t eeprom93xx_data(eeprom_t eeprom)
307	{
308	/* Get EEPROM data array. */
309	return &eeprom->contents[0];
310	}
311
312	/* eof */