1 /* 2 * MAXIM DS1338 I2C RTC+NVRAM 3 * 4 * Copyright (c) 2009 CodeSourcery. 5 * Written by Paul Brook 6 * 7 * This code is licensed under the GNU GPL v2. 8 * 9 * Contributions after 2012-01-13 are licensed under the terms of the 10 * GNU GPL, version 2 or (at your option) any later version. 11 */ 12 13 #include "qemu/osdep.h" 14 #include "qemu-common.h" 15 #include "hw/i2c/i2c.h" 16 #include "migration/vmstate.h" 17 #include "qemu/bcd.h" 18 #include "qemu/module.h" 19 20 /* Size of NVRAM including both the user-accessible area and the 21 * secondary register area. 22 */ 23 #define NVRAM_SIZE 64 24 25 /* Flags definitions */ 26 #define SECONDS_CH 0x80 27 #define HOURS_12 0x40 28 #define HOURS_PM 0x20 29 #define CTRL_OSF 0x20 30 31 #define TYPE_DS1338 "ds1338" 32 #define DS1338(obj) OBJECT_CHECK(DS1338State, (obj), TYPE_DS1338) 33 34 typedef struct DS1338State { 35 I2CSlave parent_obj; 36 37 int64_t offset; 38 uint8_t wday_offset; 39 uint8_t nvram[NVRAM_SIZE]; 40 int32_t ptr; 41 bool addr_byte; 42 } DS1338State; 43 44 static const VMStateDescription vmstate_ds1338 = { 45 .name = "ds1338", 46 .version_id = 2, 47 .minimum_version_id = 1, 48 .fields = (VMStateField[]) { 49 VMSTATE_I2C_SLAVE(parent_obj, DS1338State), 50 VMSTATE_INT64(offset, DS1338State), 51 VMSTATE_UINT8_V(wday_offset, DS1338State, 2), 52 VMSTATE_UINT8_ARRAY(nvram, DS1338State, NVRAM_SIZE), 53 VMSTATE_INT32(ptr, DS1338State), 54 VMSTATE_BOOL(addr_byte, DS1338State), 55 VMSTATE_END_OF_LIST() 56 } 57 }; 58 59 static void capture_current_time(DS1338State *s) 60 { 61 /* Capture the current time into the secondary registers 62 * which will be actually read by the data transfer operation. 63 */ 64 struct tm now; 65 qemu_get_timedate(&now, s->offset); 66 s->nvram[0] = to_bcd(now.tm_sec); 67 s->nvram[1] = to_bcd(now.tm_min); 68 if (s->nvram[2] & HOURS_12) { 69 int tmp = now.tm_hour; 70 if (tmp % 12 == 0) { 71 tmp += 12; 72 } 73 if (tmp <= 12) { 74 s->nvram[2] = HOURS_12 | to_bcd(tmp); 75 } else { 76 s->nvram[2] = HOURS_12 | HOURS_PM | to_bcd(tmp - 12); 77 } 78 } else { 79 s->nvram[2] = to_bcd(now.tm_hour); 80 } 81 s->nvram[3] = (now.tm_wday + s->wday_offset) % 7 + 1; 82 s->nvram[4] = to_bcd(now.tm_mday); 83 s->nvram[5] = to_bcd(now.tm_mon + 1); 84 s->nvram[6] = to_bcd(now.tm_year - 100); 85 } 86 87 static void inc_regptr(DS1338State *s) 88 { 89 /* The register pointer wraps around after 0x3F; wraparound 90 * causes the current time/date to be retransferred into 91 * the secondary registers. 92 */ 93 s->ptr = (s->ptr + 1) & (NVRAM_SIZE - 1); 94 if (!s->ptr) { 95 capture_current_time(s); 96 } 97 } 98 99 static int ds1338_event(I2CSlave *i2c, enum i2c_event event) 100 { 101 DS1338State *s = DS1338(i2c); 102 103 switch (event) { 104 case I2C_START_RECV: 105 /* In h/w, capture happens on any START condition, not just a 106 * START_RECV, but there is no need to actually capture on 107 * START_SEND, because the guest can't get at that data 108 * without going through a START_RECV which would overwrite it. 109 */ 110 capture_current_time(s); 111 break; 112 case I2C_START_SEND: 113 s->addr_byte = true; 114 break; 115 default: 116 break; 117 } 118 119 return 0; 120 } 121 122 static uint8_t ds1338_recv(I2CSlave *i2c) 123 { 124 DS1338State *s = DS1338(i2c); 125 uint8_t res; 126 127 res = s->nvram[s->ptr]; 128 inc_regptr(s); 129 return res; 130 } 131 132 static int ds1338_send(I2CSlave *i2c, uint8_t data) 133 { 134 DS1338State *s = DS1338(i2c); 135 136 if (s->addr_byte) { 137 s->ptr = data & (NVRAM_SIZE - 1); 138 s->addr_byte = false; 139 return 0; 140 } 141 if (s->ptr < 7) { 142 /* Time register. */ 143 struct tm now; 144 qemu_get_timedate(&now, s->offset); 145 switch(s->ptr) { 146 case 0: 147 /* TODO: Implement CH (stop) bit. */ 148 now.tm_sec = from_bcd(data & 0x7f); 149 break; 150 case 1: 151 now.tm_min = from_bcd(data & 0x7f); 152 break; 153 case 2: 154 if (data & HOURS_12) { 155 int tmp = from_bcd(data & (HOURS_PM - 1)); 156 if (data & HOURS_PM) { 157 tmp += 12; 158 } 159 if (tmp % 12 == 0) { 160 tmp -= 12; 161 } 162 now.tm_hour = tmp; 163 } else { 164 now.tm_hour = from_bcd(data & (HOURS_12 - 1)); 165 } 166 break; 167 case 3: 168 { 169 /* The day field is supposed to contain a value in 170 the range 1-7. Otherwise behavior is undefined. 171 */ 172 int user_wday = (data & 7) - 1; 173 s->wday_offset = (user_wday - now.tm_wday + 7) % 7; 174 } 175 break; 176 case 4: 177 now.tm_mday = from_bcd(data & 0x3f); 178 break; 179 case 5: 180 now.tm_mon = from_bcd(data & 0x1f) - 1; 181 break; 182 case 6: 183 now.tm_year = from_bcd(data) + 100; 184 break; 185 } 186 s->offset = qemu_timedate_diff(&now); 187 } else if (s->ptr == 7) { 188 /* Control register. */ 189 190 /* Ensure bits 2, 3 and 6 will read back as zero. */ 191 data &= 0xB3; 192 193 /* Attempting to write the OSF flag to logic 1 leaves the 194 value unchanged. */ 195 data = (data & ~CTRL_OSF) | (data & s->nvram[s->ptr] & CTRL_OSF); 196 197 s->nvram[s->ptr] = data; 198 } else { 199 s->nvram[s->ptr] = data; 200 } 201 inc_regptr(s); 202 return 0; 203 } 204 205 static void ds1338_reset(DeviceState *dev) 206 { 207 DS1338State *s = DS1338(dev); 208 209 /* The clock is running and synchronized with the host */ 210 s->offset = 0; 211 s->wday_offset = 0; 212 memset(s->nvram, 0, NVRAM_SIZE); 213 s->ptr = 0; 214 s->addr_byte = false; 215 } 216 217 static void ds1338_class_init(ObjectClass *klass, void *data) 218 { 219 DeviceClass *dc = DEVICE_CLASS(klass); 220 I2CSlaveClass *k = I2C_SLAVE_CLASS(klass); 221 222 k->event = ds1338_event; 223 k->recv = ds1338_recv; 224 k->send = ds1338_send; 225 dc->reset = ds1338_reset; 226 dc->vmsd = &vmstate_ds1338; 227 } 228 229 static const TypeInfo ds1338_info = { 230 .name = TYPE_DS1338, 231 .parent = TYPE_I2C_SLAVE, 232 .instance_size = sizeof(DS1338State), 233 .class_init = ds1338_class_init, 234 }; 235 236 static void ds1338_register_types(void) 237 { 238 type_register_static(&ds1338_info); 239 } 240 241 type_init(ds1338_register_types) 242