--- /dev/null
+/*
+ * Bit-Bang i2c emulation extracted from
+ * Marvell MV88W8618 / Freecom MusicPal emulation.
+ *
+ * Copyright (c) 2008 Jan Kiszka
+ *
+ * This code is licensed under the GNU GPL v2.
+ *
+ * Contributions after 2012-01-13 are licensed under the terms of the
+ * GNU GPL, version 2 or (at your option) any later version.
+ */
+#include "hw/hw.h"
+#include "bitbang_i2c.h"
+#include "hw/sysbus.h"
+
+//#define DEBUG_BITBANG_I2C
+
+#ifdef DEBUG_BITBANG_I2C
+#define DPRINTF(fmt, ...) \
+do { printf("bitbang_i2c: " fmt , ## __VA_ARGS__); } while (0)
+#else
+#define DPRINTF(fmt, ...) do {} while(0)
+#endif
+
+typedef enum bitbang_i2c_state {
+ STOPPED = 0,
+ SENDING_BIT7,
+ SENDING_BIT6,
+ SENDING_BIT5,
+ SENDING_BIT4,
+ SENDING_BIT3,
+ SENDING_BIT2,
+ SENDING_BIT1,
+ SENDING_BIT0,
+ WAITING_FOR_ACK,
+ RECEIVING_BIT7,
+ RECEIVING_BIT6,
+ RECEIVING_BIT5,
+ RECEIVING_BIT4,
+ RECEIVING_BIT3,
+ RECEIVING_BIT2,
+ RECEIVING_BIT1,
+ RECEIVING_BIT0,
+ SENDING_ACK,
+ SENT_NACK
+} bitbang_i2c_state;
+
+struct bitbang_i2c_interface {
+ I2CBus *bus;
+ bitbang_i2c_state state;
+ int last_data;
+ int last_clock;
+ int device_out;
+ uint8_t buffer;
+ int current_addr;
+};
+
+static void bitbang_i2c_enter_stop(bitbang_i2c_interface *i2c)
+{
+ DPRINTF("STOP\n");
+ if (i2c->current_addr >= 0)
+ i2c_end_transfer(i2c->bus);
+ i2c->current_addr = -1;
+ i2c->state = STOPPED;
+}
+
+/* Set device data pin. */
+static int bitbang_i2c_ret(bitbang_i2c_interface *i2c, int level)
+{
+ i2c->device_out = level;
+ //DPRINTF("%d %d %d\n", i2c->last_clock, i2c->last_data, i2c->device_out);
+ return level & i2c->last_data;
+}
+
+/* Leave device data pin unodified. */
+static int bitbang_i2c_nop(bitbang_i2c_interface *i2c)
+{
+ return bitbang_i2c_ret(i2c, i2c->device_out);
+}
+
+/* Returns data line level. */
+int bitbang_i2c_set(bitbang_i2c_interface *i2c, int line, int level)
+{
+ int data;
+
+ if (level != 0 && level != 1) {
+ abort();
+ }
+
+ if (line == BITBANG_I2C_SDA) {
+ if (level == i2c->last_data) {
+ return bitbang_i2c_nop(i2c);
+ }
+ i2c->last_data = level;
+ if (i2c->last_clock == 0) {
+ return bitbang_i2c_nop(i2c);
+ }
+ if (level == 0) {
+ DPRINTF("START\n");
+ /* START condition. */
+ i2c->state = SENDING_BIT7;
+ i2c->current_addr = -1;
+ } else {
+ /* STOP condition. */
+ bitbang_i2c_enter_stop(i2c);
+ }
+ return bitbang_i2c_ret(i2c, 1);
+ }
+
+ data = i2c->last_data;
+ if (i2c->last_clock == level) {
+ return bitbang_i2c_nop(i2c);
+ }
+ i2c->last_clock = level;
+ if (level == 0) {
+ /* State is set/read at the start of the clock pulse.
+ release the data line at the end. */
+ return bitbang_i2c_ret(i2c, 1);
+ }
+ switch (i2c->state) {
+ case STOPPED:
+ case SENT_NACK:
+ return bitbang_i2c_ret(i2c, 1);
+
+ case SENDING_BIT7 ... SENDING_BIT0:
+ i2c->buffer = (i2c->buffer << 1) | data;
+ /* will end up in WAITING_FOR_ACK */
+ i2c->state++;
+ return bitbang_i2c_ret(i2c, 1);
+
+ case WAITING_FOR_ACK:
+ if (i2c->current_addr < 0) {
+ i2c->current_addr = i2c->buffer;
+ DPRINTF("Address 0x%02x\n", i2c->current_addr);
+ i2c_start_transfer(i2c->bus, i2c->current_addr >> 1,
+ i2c->current_addr & 1);
+ } else {
+ DPRINTF("Sent 0x%02x\n", i2c->buffer);
+ i2c_send(i2c->bus, i2c->buffer);
+ }
+ if (i2c->current_addr & 1) {
+ i2c->state = RECEIVING_BIT7;
+ } else {
+ i2c->state = SENDING_BIT7;
+ }
+ return bitbang_i2c_ret(i2c, 0);
+
+ case RECEIVING_BIT7:
+ i2c->buffer = i2c_recv(i2c->bus);
+ DPRINTF("RX byte 0x%02x\n", i2c->buffer);
+ /* Fall through... */
+ case RECEIVING_BIT6 ... RECEIVING_BIT0:
+ data = i2c->buffer >> 7;
+ /* will end up in SENDING_ACK */
+ i2c->state++;
+ i2c->buffer <<= 1;
+ return bitbang_i2c_ret(i2c, data);
+
+ case SENDING_ACK:
+ i2c->state = RECEIVING_BIT7;
+ if (data != 0) {
+ DPRINTF("NACKED\n");
+ i2c->state = SENT_NACK;
+ i2c_nack(i2c->bus);
+ } else {
+ DPRINTF("ACKED\n");
+ }
+ return bitbang_i2c_ret(i2c, 1);
+ }
+ abort();
+}
+
+bitbang_i2c_interface *bitbang_i2c_init(I2CBus *bus)
+{
+ bitbang_i2c_interface *s;
+
+ s = g_malloc0(sizeof(bitbang_i2c_interface));
+
+ s->bus = bus;
+ s->last_data = 1;
+ s->last_clock = 1;
+ s->device_out = 1;
+
+ return s;
+}
+
+/* GPIO interface. */
+
+#define TYPE_GPIO_I2C "gpio_i2c"
+#define GPIO_I2C(obj) OBJECT_CHECK(GPIOI2CState, (obj), TYPE_GPIO_I2C)
+
+typedef struct GPIOI2CState {
+ SysBusDevice parent_obj;
+
+ MemoryRegion dummy_iomem;
+ bitbang_i2c_interface *bitbang;
+ int last_level;
+ qemu_irq out;
+} GPIOI2CState;
+
+static void bitbang_i2c_gpio_set(void *opaque, int irq, int level)
+{
+ GPIOI2CState *s = opaque;
+
+ level = bitbang_i2c_set(s->bitbang, irq, level);
+ if (level != s->last_level) {
+ s->last_level = level;
+ qemu_set_irq(s->out, level);
+ }
+}
+
+static int gpio_i2c_init(SysBusDevice *sbd)
+{
+ DeviceState *dev = DEVICE(sbd);
+ GPIOI2CState *s = GPIO_I2C(dev);
+ I2CBus *bus;
+
+ memory_region_init(&s->dummy_iomem, OBJECT(s), "gpio_i2c", 0);
+ sysbus_init_mmio(sbd, &s->dummy_iomem);
+
+ bus = i2c_init_bus(dev, "i2c");
+ s->bitbang = bitbang_i2c_init(bus);
+
+ qdev_init_gpio_in(dev, bitbang_i2c_gpio_set, 2);
+ qdev_init_gpio_out(dev, &s->out, 1);
+
+ return 0;
+}
+
+static void gpio_i2c_class_init(ObjectClass *klass, void *data)
+{
+ DeviceClass *dc = DEVICE_CLASS(klass);
+ SysBusDeviceClass *k = SYS_BUS_DEVICE_CLASS(klass);
+
+ k->init = gpio_i2c_init;
+ set_bit(DEVICE_CATEGORY_BRIDGE, dc->categories);
+ dc->desc = "Virtual GPIO to I2C bridge";
+}
+
+static const TypeInfo gpio_i2c_info = {
+ .name = TYPE_GPIO_I2C,
+ .parent = TYPE_SYS_BUS_DEVICE,
+ .instance_size = sizeof(GPIOI2CState),
+ .class_init = gpio_i2c_class_init,
+};
+
+static void bitbang_i2c_register_types(void)
+{
+ type_register_static(&gpio_i2c_info);
+}
+
+type_init(bitbang_i2c_register_types)
Code Review / kvmfornfv.git / blobdiff