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 "hw/i2c/i2c.h" 15 #include "migration/vmstate.h" 16 #include "qemu/bcd.h" 17 #include "qom/object.h" 18 #include "sysemu/rtc.h" 19 #include "trace.h" 20 21 /* Size of NVRAM including both the user-accessible area and the 22 * secondary register area. 23 */ 24 #define NVRAM_SIZE 64 25 26 /* Flags definitions */ 27 #define SECONDS_CH 0x80 28 #define HOURS_12 0x40 29 #define HOURS_PM 0x20 30 #define CTRL_OSF 0x20 31 32 #define TYPE_DS1338 "ds1338" 33 OBJECT_DECLARE_SIMPLE_TYPE(DS1338State, DS1338) 34 35 struct DS1338State { 36 I2CSlave parent_obj; 37 38 int64_t offset; 39 uint8_t wday_offset; 40 uint8_t nvram[NVRAM_SIZE]; 41 int32_t ptr; 42 bool addr_byte; 43 }; 44 45 static const VMStateDescription vmstate_ds1338 = { 46 .name = "ds1338", 47 .version_id = 2, 48 .minimum_version_id = 1, 49 .fields = (const VMStateField[]) { 50 VMSTATE_I2C_SLAVE(parent_obj, DS1338State), 51 VMSTATE_INT64(offset, DS1338State), 52 VMSTATE_UINT8_V(wday_offset, DS1338State, 2), 53 VMSTATE_UINT8_ARRAY(nvram, DS1338State, NVRAM_SIZE), 54 VMSTATE_INT32(ptr, DS1338State), 55 VMSTATE_BOOL(addr_byte, DS1338State), 56 VMSTATE_END_OF_LIST() 57 } 58 }; 59 60 static void capture_current_time(DS1338State *s) 61 { 62 /* Capture the current time into the secondary registers 63 * which will be actually read by the data transfer operation. 64 */ 65 struct tm now; 66 qemu_get_timedate(&now, s->offset); 67 s->nvram[0] = to_bcd(now.tm_sec); 68 s->nvram[1] = to_bcd(now.tm_min); 69 if (s->nvram[2] & HOURS_12) { 70 int tmp = now.tm_hour; 71 if (tmp % 12 == 0) { 72 tmp += 12; 73 } 74 if (tmp <= 12) { 75 s->nvram[2] = HOURS_12 | to_bcd(tmp); 76 } else { 77 s->nvram[2] = HOURS_12 | HOURS_PM | to_bcd(tmp - 12); 78 } 79 } else { 80 s->nvram[2] = to_bcd(now.tm_hour); 81 } 82 s->nvram[3] = (now.tm_wday + s->wday_offset) % 7 + 1; 83 s->nvram[4] = to_bcd(now.tm_mday); 84 s->nvram[5] = to_bcd(now.tm_mon + 1); 85 s->nvram[6] = to_bcd(now.tm_year - 100); 86 } 87 88 static void inc_regptr(DS1338State *s) 89 { 90 /* The register pointer wraps around after 0x3F; wraparound 91 * causes the current time/date to be retransferred into 92 * the secondary registers. 93 */ 94 s->ptr = (s->ptr + 1) & (NVRAM_SIZE - 1); 95 if (!s->ptr) { 96 capture_current_time(s); 97 } 98 } 99 100 static int ds1338_event(I2CSlave *i2c, enum i2c_event event) 101 { 102 DS1338State *s = DS1338(i2c); 103 104 switch (event) { 105 case I2C_START_RECV: 106 /* In h/w, capture happens on any START condition, not just a 107 * START_RECV, but there is no need to actually capture on 108 * START_SEND, because the guest can't get at that data 109 * without going through a START_RECV which would overwrite it. 110 */ 111 capture_current_time(s); 112 break; 113 case I2C_START_SEND: 114 s->addr_byte = true; 115 break; 116 default: 117 break; 118 } 119 120 return 0; 121 } 122 123 static uint8_t ds1338_recv(I2CSlave *i2c) 124 { 125 DS1338State *s = DS1338(i2c); 126 uint8_t res; 127 128 res = s->nvram[s->ptr]; 129 130 trace_ds1338_recv(s->ptr, res); 131 132 inc_regptr(s); 133 return res; 134 } 135 136 static int ds1338_send(I2CSlave *i2c, uint8_t data) 137 { 138 DS1338State *s = DS1338(i2c); 139 140 trace_ds1338_send(s->ptr, data); 141 142 if (s->addr_byte) { 143 s->ptr = data & (NVRAM_SIZE - 1); 144 s->addr_byte = false; 145 return 0; 146 } 147 if (s->ptr < 7) { 148 /* Time register. */ 149 struct tm now; 150 qemu_get_timedate(&now, s->offset); 151 switch(s->ptr) { 152 case 0: 153 /* TODO: Implement CH (stop) bit. */ 154 now.tm_sec = from_bcd(data & 0x7f); 155 break; 156 case 1: 157 now.tm_min = from_bcd(data & 0x7f); 158 break; 159 case 2: 160 if (data & HOURS_12) { 161 int tmp = from_bcd(data & (HOURS_PM - 1)); 162 if (data & HOURS_PM) { 163 tmp += 12; 164 } 165 if (tmp % 12 == 0) { 166 tmp -= 12; 167 } 168 now.tm_hour = tmp; 169 } else { 170 now.tm_hour = from_bcd(data & (HOURS_12 - 1)); 171 } 172 break; 173 case 3: 174 { 175 /* The day field is supposed to contain a value in 176 the range 1-7. Otherwise behavior is undefined. 177 */ 178 int user_wday = (data & 7) - 1; 179 s->wday_offset = (user_wday - now.tm_wday + 7) % 7; 180 } 181 break; 182 case 4: 183 now.tm_mday = from_bcd(data & 0x3f); 184 break; 185 case 5: 186 now.tm_mon = from_bcd(data & 0x1f) - 1; 187 break; 188 case 6: 189 now.tm_year = from_bcd(data) + 100; 190 break; 191 } 192 s->offset = qemu_timedate_diff(&now); 193 } else if (s->ptr == 7) { 194 /* Control register. */ 195 196 /* Ensure bits 2, 3 and 6 will read back as zero. */ 197 data &= 0xB3; 198 199 /* Attempting to write the OSF flag to logic 1 leaves the 200 value unchanged. */ 201 data = (data & ~CTRL_OSF) | (data & s->nvram[s->ptr] & CTRL_OSF); 202 203 s->nvram[s->ptr] = data; 204 } else { 205 s->nvram[s->ptr] = data; 206 } 207 inc_regptr(s); 208 return 0; 209 } 210 211 static void ds1338_reset(DeviceState *dev) 212 { 213 DS1338State *s = DS1338(dev); 214 215 /* The clock is running and synchronized with the host */ 216 s->offset = 0; 217 s->wday_offset = 0; 218 memset(s->nvram, 0, NVRAM_SIZE); 219 s->ptr = 0; 220 s->addr_byte = false; 221 } 222 223 static void ds1338_class_init(ObjectClass *klass, void *data) 224 { 225 DeviceClass *dc = DEVICE_CLASS(klass); 226 I2CSlaveClass *k = I2C_SLAVE_CLASS(klass); 227 228 k->event = ds1338_event; 229 k->recv = ds1338_recv; 230 k->send = ds1338_send; 231 device_class_set_legacy_reset(dc, ds1338_reset); 232 dc->vmsd = &vmstate_ds1338; 233 } 234 235 static const TypeInfo ds1338_types[] = { 236 { 237 .name = TYPE_DS1338, 238 .parent = TYPE_I2C_SLAVE, 239 .instance_size = sizeof(DS1338State), 240 .class_init = ds1338_class_init, 241 }, 242 }; 243 244 DEFINE_TYPES(ds1338_types) 245