xref: /qemu/hw/gpio/pca9554.c (revision 3d881164d4fb2b0f6791cf28d9725926b8ded0d6) 
1 /*
2  * PCA9554 I/O port
3  *
4  * Copyright (c) 2023, IBM Corporation.
5  *
6  * SPDX-License-Identifier: GPL-2.0-or-later
7  */
8 
9 #include "qemu/osdep.h"
10 #include "qemu/log.h"
11 #include "qemu/module.h"
12 #include "qemu/bitops.h"
13 #include "hw/qdev-properties.h"
14 #include "hw/gpio/pca9554.h"
15 #include "hw/gpio/pca9554_regs.h"
16 #include "hw/irq.h"
17 #include "migration/vmstate.h"
18 #include "qapi/error.h"
19 #include "qapi/visitor.h"
20 #include "trace.h"
21 #include "qom/object.h"
22 
23 struct PCA9554Class {
24     /*< private >*/
25     I2CSlaveClass parent_class;
26     /*< public >*/
27 };
28 typedef struct PCA9554Class PCA9554Class;
29 
30 DECLARE_CLASS_CHECKERS(PCA9554Class, PCA9554,
31                        TYPE_PCA9554)
32 
33 #define PCA9554_PIN_LOW  0x0
34 #define PCA9554_PIN_HIZ  0x1
35 
36 static const char *pin_state[] = {"low", "high"};
37 
38 static void pca9554_update_pin_input(PCA9554State *s)
39 {
40     int i;
41     uint8_t config = s->regs[PCA9554_CONFIG];
42     uint8_t output = s->regs[PCA9554_OUTPUT];
43     uint8_t internal_state = config | output;
44 
45     for (i = 0; i < PCA9554_PIN_COUNT; i++) {
46         uint8_t bit_mask = 1 << i;
47         uint8_t internal_pin_state = (internal_state >> i) & 0x1;
48         uint8_t old_value = s->regs[PCA9554_INPUT] & bit_mask;
49         uint8_t new_value;
50 
51         switch (internal_pin_state) {
52         case PCA9554_PIN_LOW:
53             s->regs[PCA9554_INPUT] &= ~bit_mask;
54             break;
55         case PCA9554_PIN_HIZ:
56             /*
57              * pullup sets it to a logical 1 unless
58              * external device drives it low.
59              */
60             if (s->ext_state[i] == PCA9554_PIN_LOW) {
61                 s->regs[PCA9554_INPUT] &= ~bit_mask;
62             } else {
63                 s->regs[PCA9554_INPUT] |=  bit_mask;
64             }
65             break;
66         default:
67             break;
68         }
69 
70         /* update irq state only if pin state changed */
71         new_value = s->regs[PCA9554_INPUT] & bit_mask;
72         if (new_value != old_value) {
73             if (new_value) {
74                 /* changed from 0 to 1 */
75                 qemu_set_irq(s->gpio_out[i], 1);
76             } else {
77                 /* changed from 1 to 0 */
78                 qemu_set_irq(s->gpio_out[i], 0);
79             }
80         }
81     }
82 }
83 
84 static uint8_t pca9554_read(PCA9554State *s, uint8_t reg)
85 {
86     switch (reg) {
87     case PCA9554_INPUT:
88         return s->regs[PCA9554_INPUT] ^ s->regs[PCA9554_POLARITY];
89     case PCA9554_OUTPUT:
90     case PCA9554_POLARITY:
91     case PCA9554_CONFIG:
92         return s->regs[reg];
93     default:
94         qemu_log_mask(LOG_GUEST_ERROR, "%s: unexpected read to register %d\n",
95                       __func__, reg);
96         return 0xFF;
97     }
98 }
99 
100 static void pca9554_write(PCA9554State *s, uint8_t reg, uint8_t data)
101 {
102     switch (reg) {
103     case PCA9554_OUTPUT:
104     case PCA9554_CONFIG:
105         s->regs[reg] = data;
106         pca9554_update_pin_input(s);
107         break;
108     case PCA9554_POLARITY:
109         s->regs[reg] = data;
110         break;
111     case PCA9554_INPUT:
112     default:
113         qemu_log_mask(LOG_GUEST_ERROR, "%s: unexpected write to register %d\n",
114                       __func__, reg);
115     }
116 }
117 
118 static uint8_t pca9554_recv(I2CSlave *i2c)
119 {
120     PCA9554State *s = PCA9554(i2c);
121 
122     return pca9554_read(s, s->pointer & 0x3);
123 }
124 
125 static int pca9554_send(I2CSlave *i2c, uint8_t data)
126 {
127     PCA9554State *s = PCA9554(i2c);
128 
129     /* First byte sent by is the register address */
130     if (s->len == 0) {
131         s->pointer = data;
132         s->len++;
133     } else {
134         pca9554_write(s, s->pointer & 0x3, data);
135     }
136 
137     return 0;
138 }
139 
140 static int pca9554_event(I2CSlave *i2c, enum i2c_event event)
141 {
142     PCA9554State *s = PCA9554(i2c);
143 
144     s->len = 0;
145     return 0;
146 }
147 
148 static void pca9554_get_pin(Object *obj, Visitor *v, const char *name,
149                             void *opaque, Error **errp)
150 {
151     PCA9554State *s = PCA9554(obj);
152     int pin, rc;
153     uint8_t state;
154 
155     rc = sscanf(name, "pin%2d", &pin);
156     if (rc != 1) {
157         error_setg(errp, "%s: error reading %s", __func__, name);
158         return;
159     }
160     if (pin < 0 || pin >= PCA9554_PIN_COUNT) {
161         error_setg(errp, "%s invalid pin %s", __func__, name);
162         return;
163     }
164 
165     state = pca9554_read(s, PCA9554_CONFIG);
166     state |= pca9554_read(s, PCA9554_OUTPUT);
167     state = (state >> pin) & 0x1;
168     visit_type_str(v, name, (char **)&pin_state[state], errp);
169 }
170 
171 static void pca9554_set_pin(Object *obj, Visitor *v, const char *name,
172                             void *opaque, Error **errp)
173 {
174     PCA9554State *s = PCA9554(obj);
175     int pin, rc, val;
176     uint8_t state, mask;
177     char *state_str;
178 
179     if (!visit_type_str(v, name, &state_str, errp)) {
180         return;
181     }
182     rc = sscanf(name, "pin%2d", &pin);
183     if (rc != 1) {
184         error_setg(errp, "%s: error reading %s", __func__, name);
185         return;
186     }
187     if (pin < 0 || pin >= PCA9554_PIN_COUNT) {
188         error_setg(errp, "%s invalid pin %s", __func__, name);
189         return;
190     }
191 
192     for (state = 0; state < ARRAY_SIZE(pin_state); state++) {
193         if (!strcmp(state_str, pin_state[state])) {
194             break;
195         }
196     }
197     if (state >= ARRAY_SIZE(pin_state)) {
198         error_setg(errp, "%s invalid pin state %s", __func__, state_str);
199         return;
200     }
201 
202     /* First, modify the output register bit */
203     val = pca9554_read(s, PCA9554_OUTPUT);
204     mask = 0x1 << pin;
205     if (state == PCA9554_PIN_LOW) {
206         val &= ~(mask);
207     } else {
208         val |= mask;
209     }
210     pca9554_write(s, PCA9554_OUTPUT, val);
211 
212     /* Then, clear the config register bit for output mode */
213     val = pca9554_read(s, PCA9554_CONFIG);
214     val &= ~mask;
215     pca9554_write(s, PCA9554_CONFIG, val);
216 }
217 
218 static const VMStateDescription pca9554_vmstate = {
219     .name = "PCA9554",
220     .version_id = 0,
221     .minimum_version_id = 0,
222     .fields = (VMStateField[]) {
223         VMSTATE_UINT8(len, PCA9554State),
224         VMSTATE_UINT8(pointer, PCA9554State),
225         VMSTATE_UINT8_ARRAY(regs, PCA9554State, PCA9554_NR_REGS),
226         VMSTATE_UINT8_ARRAY(ext_state, PCA9554State, PCA9554_PIN_COUNT),
227         VMSTATE_I2C_SLAVE(i2c, PCA9554State),
228         VMSTATE_END_OF_LIST()
229     }
230 };
231 
232 static void pca9554_reset(DeviceState *dev)
233 {
234     PCA9554State *s = PCA9554(dev);
235 
236     s->regs[PCA9554_INPUT] = 0xFF;
237     s->regs[PCA9554_OUTPUT] = 0xFF;
238     s->regs[PCA9554_POLARITY] = 0x0; /* No pins are inverted */
239     s->regs[PCA9554_CONFIG] = 0xFF; /* All pins are inputs */
240 
241     memset(s->ext_state, PCA9554_PIN_HIZ, PCA9554_PIN_COUNT);
242     pca9554_update_pin_input(s);
243 
244     s->pointer = 0x0;
245     s->len = 0;
246 }
247 
248 static void pca9554_initfn(Object *obj)
249 {
250     int pin;
251 
252     for (pin = 0; pin < PCA9554_PIN_COUNT; pin++) {
253         char *name;
254 
255         name = g_strdup_printf("pin%d", pin);
256         object_property_add(obj, name, "bool", pca9554_get_pin, pca9554_set_pin,
257                             NULL, NULL);
258         g_free(name);
259     }
260 }
261 
262 static void pca9554_set_ext_state(PCA9554State *s, int pin, int level)
263 {
264     if (s->ext_state[pin] != level) {
265         s->ext_state[pin] = level;
266         pca9554_update_pin_input(s);
267     }
268 }
269 
270 static void pca9554_gpio_in_handler(void *opaque, int pin, int level)
271 {
272 
273     PCA9554State *s = PCA9554(opaque);
274 
275     assert((pin >= 0) && (pin < PCA9554_PIN_COUNT));
276     pca9554_set_ext_state(s, pin, level);
277 }
278 
279 static void pca9554_realize(DeviceState *dev, Error **errp)
280 {
281     PCA9554State *s = PCA9554(dev);
282 
283     if (!s->description) {
284         s->description = g_strdup("pca9554");
285     }
286 
287     qdev_init_gpio_out(dev, s->gpio_out, PCA9554_PIN_COUNT);
288     qdev_init_gpio_in(dev, pca9554_gpio_in_handler, PCA9554_PIN_COUNT);
289 }
290 
291 static const Property pca9554_properties[] = {
292     DEFINE_PROP_STRING("description", PCA9554State, description),
293 };
294 
295 static void pca9554_class_init(ObjectClass *klass, const void *data)
296 {
297     DeviceClass *dc = DEVICE_CLASS(klass);
298     I2CSlaveClass *k = I2C_SLAVE_CLASS(klass);
299 
300     k->event = pca9554_event;
301     k->recv = pca9554_recv;
302     k->send = pca9554_send;
303     dc->realize = pca9554_realize;
304     device_class_set_legacy_reset(dc, pca9554_reset);
305     dc->vmsd = &pca9554_vmstate;
306     device_class_set_props(dc, pca9554_properties);
307 }
308 
309 static const TypeInfo pca9554_info = {
310     .name          = TYPE_PCA9554,
311     .parent        = TYPE_I2C_SLAVE,
312     .instance_init = pca9554_initfn,
313     .instance_size = sizeof(PCA9554State),
314     .class_init    = pca9554_class_init,
315     .class_size    = sizeof(PCA9554Class),
316     .abstract      = false,
317 };
318 
319 static void pca9554_register_types(void)
320 {
321     type_register_static(&pca9554_info);
322 }
323 
324 type_init(pca9554_register_types)
325