xref: /qemu/hw/gpio/pca9554.c (revision 2c4815590f9ea399bc87f727dd1c883b0d701bb8) 
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      uint8_t ret;
122  
123      ret = pca9554_read(s, s->pointer & 0x3);
124  
125      return ret;
126  }
127  
128  static int pca9554_send(I2CSlave *i2c, uint8_t data)
129  {
130      PCA9554State *s = PCA9554(i2c);
131  
132      /* First byte sent by is the register address */
133      if (s->len == 0) {
134          s->pointer = data;
135          s->len++;
136      } else {
137          pca9554_write(s, s->pointer & 0x3, data);
138      }
139  
140      return 0;
141  }
142  
143  static int pca9554_event(I2CSlave *i2c, enum i2c_event event)
144  {
145      PCA9554State *s = PCA9554(i2c);
146  
147      s->len = 0;
148      return 0;
149  }
150  
151  static void pca9554_get_pin(Object *obj, Visitor *v, const char *name,
152                              void *opaque, Error **errp)
153  {
154      PCA9554State *s = PCA9554(obj);
155      int pin, rc;
156      uint8_t state;
157  
158      rc = sscanf(name, "pin%2d", &pin);
159      if (rc != 1) {
160          error_setg(errp, "%s: error reading %s", __func__, name);
161          return;
162      }
163      if (pin < 0 || pin >= PCA9554_PIN_COUNT) {
164          error_setg(errp, "%s invalid pin %s", __func__, name);
165          return;
166      }
167  
168      state = pca9554_read(s, PCA9554_CONFIG);
169      state |= pca9554_read(s, PCA9554_OUTPUT);
170      state = (state >> pin) & 0x1;
171      visit_type_str(v, name, (char **)&pin_state[state], errp);
172  }
173  
174  static void pca9554_set_pin(Object *obj, Visitor *v, const char *name,
175                              void *opaque, Error **errp)
176  {
177      PCA9554State *s = PCA9554(obj);
178      int pin, rc, val;
179      uint8_t state, mask;
180      char *state_str;
181  
182      if (!visit_type_str(v, name, &state_str, errp)) {
183          return;
184      }
185      rc = sscanf(name, "pin%2d", &pin);
186      if (rc != 1) {
187          error_setg(errp, "%s: error reading %s", __func__, name);
188          return;
189      }
190      if (pin < 0 || pin >= PCA9554_PIN_COUNT) {
191          error_setg(errp, "%s invalid pin %s", __func__, name);
192          return;
193      }
194  
195      for (state = 0; state < ARRAY_SIZE(pin_state); state++) {
196          if (!strcmp(state_str, pin_state[state])) {
197              break;
198          }
199      }
200      if (state >= ARRAY_SIZE(pin_state)) {
201          error_setg(errp, "%s invalid pin state %s", __func__, state_str);
202          return;
203      }
204  
205      /* First, modify the output register bit */
206      val = pca9554_read(s, PCA9554_OUTPUT);
207      mask = 0x1 << pin;
208      if (state == PCA9554_PIN_LOW) {
209          val &= ~(mask);
210      } else {
211          val |= mask;
212      }
213      pca9554_write(s, PCA9554_OUTPUT, val);
214  
215      /* Then, clear the config register bit for output mode */
216      val = pca9554_read(s, PCA9554_CONFIG);
217      val &= ~mask;
218      pca9554_write(s, PCA9554_CONFIG, val);
219  }
220  
221  static const VMStateDescription pca9554_vmstate = {
222      .name = "PCA9554",
223      .version_id = 0,
224      .minimum_version_id = 0,
225      .fields = (VMStateField[]) {
226          VMSTATE_UINT8(len, PCA9554State),
227          VMSTATE_UINT8(pointer, PCA9554State),
228          VMSTATE_UINT8_ARRAY(regs, PCA9554State, PCA9554_NR_REGS),
229          VMSTATE_UINT8_ARRAY(ext_state, PCA9554State, PCA9554_PIN_COUNT),
230          VMSTATE_I2C_SLAVE(i2c, PCA9554State),
231          VMSTATE_END_OF_LIST()
232      }
233  };
234  
235  static void pca9554_reset(DeviceState *dev)
236  {
237      PCA9554State *s = PCA9554(dev);
238  
239      s->regs[PCA9554_INPUT] = 0xFF;
240      s->regs[PCA9554_OUTPUT] = 0xFF;
241      s->regs[PCA9554_POLARITY] = 0x0; /* No pins are inverted */
242      s->regs[PCA9554_CONFIG] = 0xFF; /* All pins are inputs */
243  
244      memset(s->ext_state, PCA9554_PIN_HIZ, PCA9554_PIN_COUNT);
245      pca9554_update_pin_input(s);
246  
247      s->pointer = 0x0;
248      s->len = 0;
249  }
250  
251  static void pca9554_initfn(Object *obj)
252  {
253      int pin;
254  
255      for (pin = 0; pin < PCA9554_PIN_COUNT; pin++) {
256          char *name;
257  
258          name = g_strdup_printf("pin%d", pin);
259          object_property_add(obj, name, "bool", pca9554_get_pin, pca9554_set_pin,
260                              NULL, NULL);
261          g_free(name);
262      }
263  }
264  
265  static void pca9554_set_ext_state(PCA9554State *s, int pin, int level)
266  {
267      if (s->ext_state[pin] != level) {
268          s->ext_state[pin] = level;
269          pca9554_update_pin_input(s);
270      }
271  }
272  
273  static void pca9554_gpio_in_handler(void *opaque, int pin, int level)
274  {
275  
276      PCA9554State *s = PCA9554(opaque);
277  
278      assert((pin >= 0) && (pin < PCA9554_PIN_COUNT));
279      pca9554_set_ext_state(s, pin, level);
280  }
281  
282  static void pca9554_realize(DeviceState *dev, Error **errp)
283  {
284      PCA9554State *s = PCA9554(dev);
285  
286      if (!s->description) {
287          s->description = g_strdup("pca9554");
288      }
289  
290      qdev_init_gpio_out(dev, s->gpio_out, PCA9554_PIN_COUNT);
291      qdev_init_gpio_in(dev, pca9554_gpio_in_handler, PCA9554_PIN_COUNT);
292  }
293  
294  static const Property pca9554_properties[] = {
295      DEFINE_PROP_STRING("description", PCA9554State, description),
296  };
297  
298  static void pca9554_class_init(ObjectClass *klass, void *data)
299  {
300      DeviceClass *dc = DEVICE_CLASS(klass);
301      I2CSlaveClass *k = I2C_SLAVE_CLASS(klass);
302  
303      k->event = pca9554_event;
304      k->recv = pca9554_recv;
305      k->send = pca9554_send;
306      dc->realize = pca9554_realize;
307      device_class_set_legacy_reset(dc, pca9554_reset);
308      dc->vmsd = &pca9554_vmstate;
309      device_class_set_props(dc, pca9554_properties);
310  }
311  
312  static const TypeInfo pca9554_info = {
313      .name          = TYPE_PCA9554,
314      .parent        = TYPE_I2C_SLAVE,
315      .instance_init = pca9554_initfn,
316      .instance_size = sizeof(PCA9554State),
317      .class_init    = pca9554_class_init,
318      .class_size    = sizeof(PCA9554Class),
319      .abstract      = false,
320  };
321  
322  static void pca9554_register_types(void)
323  {
324      type_register_static(&pca9554_info);
325  }
326  
327  type_init(pca9554_register_types)
328