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 #include "qom/object.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 = (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
capture_current_time(DS1338State * s)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
inc_regptr(DS1338State * s)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
ds1338_event(I2CSlave * i2c,enum i2c_event event)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
ds1338_recv(I2CSlave * i2c)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 inc_regptr(s);
130 return res;
131 }
132
ds1338_send(I2CSlave * i2c,uint8_t data)133 static int ds1338_send(I2CSlave *i2c, uint8_t data)
134 {
135 DS1338State *s = DS1338(i2c);
136
137 if (s->addr_byte) {
138 s->ptr = data & (NVRAM_SIZE - 1);
139 s->addr_byte = false;
140 return 0;
141 }
142 if (s->ptr < 7) {
143 /* Time register. */
144 struct tm now;
145 qemu_get_timedate(&now, s->offset);
146 switch(s->ptr) {
147 case 0:
148 /* TODO: Implement CH (stop) bit. */
149 now.tm_sec = from_bcd(data & 0x7f);
150 break;
151 case 1:
152 now.tm_min = from_bcd(data & 0x7f);
153 break;
154 case 2:
155 if (data & HOURS_12) {
156 int tmp = from_bcd(data & (HOURS_PM - 1));
157 if (data & HOURS_PM) {
158 tmp += 12;
159 }
160 if (tmp % 12 == 0) {
161 tmp -= 12;
162 }
163 now.tm_hour = tmp;
164 } else {
165 now.tm_hour = from_bcd(data & (HOURS_12 - 1));
166 }
167 break;
168 case 3:
169 {
170 /* The day field is supposed to contain a value in
171 the range 1-7. Otherwise behavior is undefined.
172 */
173 int user_wday = (data & 7) - 1;
174 s->wday_offset = (user_wday - now.tm_wday + 7) % 7;
175 }
176 break;
177 case 4:
178 now.tm_mday = from_bcd(data & 0x3f);
179 break;
180 case 5:
181 now.tm_mon = from_bcd(data & 0x1f) - 1;
182 break;
183 case 6:
184 now.tm_year = from_bcd(data) + 100;
185 break;
186 }
187 s->offset = qemu_timedate_diff(&now);
188 } else if (s->ptr == 7) {
189 /* Control register. */
190
191 /* Ensure bits 2, 3 and 6 will read back as zero. */
192 data &= 0xB3;
193
194 /* Attempting to write the OSF flag to logic 1 leaves the
195 value unchanged. */
196 data = (data & ~CTRL_OSF) | (data & s->nvram[s->ptr] & CTRL_OSF);
197
198 s->nvram[s->ptr] = data;
199 } else {
200 s->nvram[s->ptr] = data;
201 }
202 inc_regptr(s);
203 return 0;
204 }
205
ds1338_reset(DeviceState * dev)206 static void ds1338_reset(DeviceState *dev)
207 {
208 DS1338State *s = DS1338(dev);
209
210 /* The clock is running and synchronized with the host */
211 s->offset = 0;
212 s->wday_offset = 0;
213 memset(s->nvram, 0, NVRAM_SIZE);
214 s->ptr = 0;
215 s->addr_byte = false;
216 }
217
ds1338_class_init(ObjectClass * klass,void * data)218 static void ds1338_class_init(ObjectClass *klass, void *data)
219 {
220 DeviceClass *dc = DEVICE_CLASS(klass);
221 I2CSlaveClass *k = I2C_SLAVE_CLASS(klass);
222
223 k->event = ds1338_event;
224 k->recv = ds1338_recv;
225 k->send = ds1338_send;
226 dc->reset = ds1338_reset;
227 dc->vmsd = &vmstate_ds1338;
228 }
229
230 static const TypeInfo ds1338_info = {
231 .name = TYPE_DS1338,
232 .parent = TYPE_I2C_SLAVE,
233 .instance_size = sizeof(DS1338State),
234 .class_init = ds1338_class_init,
235 };
236
ds1338_register_types(void)237 static void ds1338_register_types(void)
238 {
239 type_register_static(&ds1338_info);
240 }
241
242 type_init(ds1338_register_types)
243