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qemu/hw/misc/pca9554.c
Glenn Miles de0c7d543b misc: Add a pca9554 GPIO device model 
Specs are available here:

    https://www.nxp.com/docs/en/data-sheet/PCA9554_9554A.pdf

This is a simple model supporting the basic registers for GPIO
mode.  The device also supports an interrupt output line but the
model does not yet support this.

Reviewed-by: Cédric Le Goater <clg@kaod.org>
Signed-off-by: Glenn Miles <milesg@linux.vnet.ibm.com>
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
2024-02-23 23:24:42 +10:00

329 lines
8.4 KiB
C
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/*
* PCA9554 I/O port
*
* Copyright (c) 2023, IBM Corporation.
*
* SPDX-License-Identifier: GPL-2.0-or-later
*/
#include "qemu/osdep.h"
#include "qemu/log.h"
#include "qemu/module.h"
#include "qemu/bitops.h"
#include "hw/qdev-properties.h"
#include "hw/misc/pca9554.h"
#include "hw/misc/pca9554_regs.h"
#include "hw/irq.h"
#include "migration/vmstate.h"
#include "qapi/error.h"
#include "qapi/visitor.h"
#include "trace.h"
#include "qom/object.h"
struct PCA9554Class {
/*< private >*/
I2CSlaveClass parent_class;
/*< public >*/
};
typedef struct PCA9554Class PCA9554Class;
DECLARE_CLASS_CHECKERS(PCA9554Class, PCA9554,
TYPE_PCA9554)
#define PCA9554_PIN_LOW 0x0
#define PCA9554_PIN_HIZ 0x1
static const char *pin_state[] = {"low", "high"};
static void pca9554_update_pin_input(PCA9554State *s)
{
int i;
uint8_t config = s->regs[PCA9554_CONFIG];
uint8_t output = s->regs[PCA9554_OUTPUT];
uint8_t internal_state = config | output;
for (i = 0; i < PCA9554_PIN_COUNT; i++) {
uint8_t bit_mask = 1 << i;
uint8_t internal_pin_state = (internal_state >> i) & 0x1;
uint8_t old_value = s->regs[PCA9554_INPUT] & bit_mask;
uint8_t new_value;
switch (internal_pin_state) {
case PCA9554_PIN_LOW:
s->regs[PCA9554_INPUT] &= ~bit_mask;
break;
case PCA9554_PIN_HIZ:
/*
* pullup sets it to a logical 1 unless
* external device drives it low.
*/
if (s->ext_state[i] == PCA9554_PIN_LOW) {
s->regs[PCA9554_INPUT] &= ~bit_mask;
} else {
s->regs[PCA9554_INPUT] |= bit_mask;
}
break;
default:
break;
}
/* update irq state only if pin state changed */
new_value = s->regs[PCA9554_INPUT] & bit_mask;
if (new_value != old_value) {
if (new_value) {
/* changed from 0 to 1 */
qemu_set_irq(s->gpio_out[i], 1);
} else {
/* changed from 1 to 0 */
qemu_set_irq(s->gpio_out[i], 0);
}
}
}
}
static uint8_t pca9554_read(PCA9554State *s, uint8_t reg)
{
switch (reg) {
case PCA9554_INPUT:
return s->regs[PCA9554_INPUT] ^ s->regs[PCA9554_POLARITY];
case PCA9554_OUTPUT:
case PCA9554_POLARITY:
case PCA9554_CONFIG:
return s->regs[reg];
default:
qemu_log_mask(LOG_GUEST_ERROR, "%s: unexpected read to register %d\n",
__func__, reg);
return 0xFF;
}
}
static void pca9554_write(PCA9554State *s, uint8_t reg, uint8_t data)
{
switch (reg) {
case PCA9554_OUTPUT:
case PCA9554_CONFIG:
s->regs[reg] = data;
pca9554_update_pin_input(s);
break;
case PCA9554_POLARITY:
s->regs[reg] = data;
break;
case PCA9554_INPUT:
default:
qemu_log_mask(LOG_GUEST_ERROR, "%s: unexpected write to register %d\n",
__func__, reg);
}
}
static uint8_t pca9554_recv(I2CSlave *i2c)
{
PCA9554State *s = PCA9554(i2c);
uint8_t ret;
ret = pca9554_read(s, s->pointer & 0x3);
return ret;
}
static int pca9554_send(I2CSlave *i2c, uint8_t data)
{
PCA9554State *s = PCA9554(i2c);
/* First byte sent by is the register address */
if (s->len == 0) {
s->pointer = data;
s->len++;
} else {
pca9554_write(s, s->pointer & 0x3, data);
}
return 0;
}
static int pca9554_event(I2CSlave *i2c, enum i2c_event event)
{
PCA9554State *s = PCA9554(i2c);
s->len = 0;
return 0;
}
static void pca9554_get_pin(Object *obj, Visitor *v, const char *name,
void *opaque, Error **errp)
{
PCA9554State *s = PCA9554(obj);
int pin, rc;
uint8_t state;
rc = sscanf(name, "pin%2d", &pin);
if (rc != 1) {
error_setg(errp, "%s: error reading %s", __func__, name);
return;
}
if (pin < 0 || pin > PCA9554_PIN_COUNT) {
error_setg(errp, "%s invalid pin %s", __func__, name);
return;
}
state = pca9554_read(s, PCA9554_CONFIG);
state |= pca9554_read(s, PCA9554_OUTPUT);
state = (state >> pin) & 0x1;
visit_type_str(v, name, (char **)&pin_state[state], errp);
}
static void pca9554_set_pin(Object *obj, Visitor *v, const char *name,
void *opaque, Error **errp)
{
PCA9554State *s = PCA9554(obj);
int pin, rc, val;
uint8_t state, mask;
char *state_str;
if (!visit_type_str(v, name, &state_str, errp)) {
return;
}
rc = sscanf(name, "pin%2d", &pin);
if (rc != 1) {
error_setg(errp, "%s: error reading %s", __func__, name);
return;
}
if (pin < 0 || pin > PCA9554_PIN_COUNT) {
error_setg(errp, "%s invalid pin %s", __func__, name);
return;
}
for (state = 0; state < ARRAY_SIZE(pin_state); state++) {
if (!strcmp(state_str, pin_state[state])) {
break;
}
}
if (state >= ARRAY_SIZE(pin_state)) {
error_setg(errp, "%s invalid pin state %s", __func__, state_str);
return;
}
/* First, modify the output register bit */
val = pca9554_read(s, PCA9554_OUTPUT);
mask = 0x1 << pin;
if (state == PCA9554_PIN_LOW) {
val &= ~(mask);
} else {
val |= mask;
}
pca9554_write(s, PCA9554_OUTPUT, val);
/* Then, clear the config register bit for output mode */
val = pca9554_read(s, PCA9554_CONFIG);
val &= ~mask;
pca9554_write(s, PCA9554_CONFIG, val);
}
static const VMStateDescription pca9554_vmstate = {
.name = "PCA9554",
.version_id = 0,
.minimum_version_id = 0,
.fields = (VMStateField[]) {
VMSTATE_UINT8(len, PCA9554State),
VMSTATE_UINT8(pointer, PCA9554State),
VMSTATE_UINT8_ARRAY(regs, PCA9554State, PCA9554_NR_REGS),
VMSTATE_UINT8_ARRAY(ext_state, PCA9554State, PCA9554_PIN_COUNT),
VMSTATE_I2C_SLAVE(i2c, PCA9554State),
VMSTATE_END_OF_LIST()
}
};
static void pca9554_reset(DeviceState *dev)
{
PCA9554State *s = PCA9554(dev);
s->regs[PCA9554_INPUT] = 0xFF;
s->regs[PCA9554_OUTPUT] = 0xFF;
s->regs[PCA9554_POLARITY] = 0x0; /* No pins are inverted */
s->regs[PCA9554_CONFIG] = 0xFF; /* All pins are inputs */
memset(s->ext_state, PCA9554_PIN_HIZ, PCA9554_PIN_COUNT);
pca9554_update_pin_input(s);
s->pointer = 0x0;
s->len = 0;
}
static void pca9554_initfn(Object *obj)
{
int pin;
for (pin = 0; pin < PCA9554_PIN_COUNT; pin++) {
char *name;
name = g_strdup_printf("pin%d", pin);
object_property_add(obj, name, "bool", pca9554_get_pin, pca9554_set_pin,
NULL, NULL);
g_free(name);
}
}
static void pca9554_set_ext_state(PCA9554State *s, int pin, int level)
{
if (s->ext_state[pin] != level) {
s->ext_state[pin] = level;
pca9554_update_pin_input(s);
}
}
static void pca9554_gpio_in_handler(void *opaque, int pin, int level)
{
PCA9554State *s = PCA9554(opaque);
assert((pin >= 0) && (pin < PCA9554_PIN_COUNT));
pca9554_set_ext_state(s, pin, level);
}
static void pca9554_realize(DeviceState *dev, Error **errp)
{
PCA9554State *s = PCA9554(dev);
if (!s->description) {
s->description = g_strdup("pca9554");
}
qdev_init_gpio_out(dev, s->gpio_out, PCA9554_PIN_COUNT);
qdev_init_gpio_in(dev, pca9554_gpio_in_handler, PCA9554_PIN_COUNT);
}
static Property pca9554_properties[] = {
DEFINE_PROP_STRING("description", PCA9554State, description),
DEFINE_PROP_END_OF_LIST(),
};
static void pca9554_class_init(ObjectClass *klass, void *data)
{
DeviceClass *dc = DEVICE_CLASS(klass);
I2CSlaveClass *k = I2C_SLAVE_CLASS(klass);
k->event = pca9554_event;
k->recv = pca9554_recv;
k->send = pca9554_send;
dc->realize = pca9554_realize;
dc->reset = pca9554_reset;
dc->vmsd = &pca9554_vmstate;
device_class_set_props(dc, pca9554_properties);
}
static const TypeInfo pca9554_info = {
.name = TYPE_PCA9554,
.parent = TYPE_I2C_SLAVE,
.instance_init = pca9554_initfn,
.instance_size = sizeof(PCA9554State),
.class_init = pca9554_class_init,
.class_size = sizeof(PCA9554Class),
.abstract = false,
};
static void pca9554_register_types(void)
{
type_register_static(&pca9554_info);
}
type_init(pca9554_register_types)
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