/*
* Broadcom Serial Controller (BSC)
*
* Copyright (c) 2024 Rayhan Faizel <rayhan.faizel@gmail.com>
*
* SPDX-License-Identifier: MIT
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
#include "qemu/osdep.h"
#include "qemu/log.h"
#include "hw/i2c/bcm2835_i2c.h"
#include "hw/irq.h"
#include "migration/vmstate.h"
static void bcm2835_i2c_update_interrupt(BCM2835I2CState *s)
{
int do_interrupt = 0;
/* Interrupt on RXR (Needs reading) */
if (s->c & BCM2835_I2C_C_INTR && s->s & BCM2835_I2C_S_RXR) {
do_interrupt = 1;
}
/* Interrupt on TXW (Needs writing) */
if (s->c & BCM2835_I2C_C_INTT && s->s & BCM2835_I2C_S_TXW) {
do_interrupt = 1;
}
/* Interrupt on DONE (Transfer complete) */
if (s->c & BCM2835_I2C_C_INTD && s->s & BCM2835_I2C_S_DONE) {
do_interrupt = 1;
}
qemu_set_irq(s->irq, do_interrupt);
}
static void bcm2835_i2c_begin_transfer(BCM2835I2CState *s)
{
int direction = s->c & BCM2835_I2C_C_READ;
if (i2c_start_transfer(s->bus, s->a, direction)) {
s->s |= BCM2835_I2C_S_ERR;
}
s->s |= BCM2835_I2C_S_TA;
if (direction) {
s->s |= BCM2835_I2C_S_RXR | BCM2835_I2C_S_RXD;
} else {
s->s |= BCM2835_I2C_S_TXW;
}
}
static void bcm2835_i2c_finish_transfer(BCM2835I2CState *s)
{
/*
* STOP is sent when DLEN counts down to zero.
*
* https://github.com/torvalds/linux/blob/v6.7/drivers/i2c/busses/i2c-bcm2835.c#L223-L261
* It is possible to initiate repeated starts on real hardware.
* However, this requires sending another ST request before the bytes in
* TX FIFO are shifted out.
*
* This is not emulated currently.
*/
i2c_end_transfer(s->bus);
s->s |= BCM2835_I2C_S_DONE;
/* Ensure RXD is cleared, otherwise the driver registers an error */
s->s &= ~(BCM2835_I2C_S_TA | BCM2835_I2C_S_RXR |
BCM2835_I2C_S_TXW | BCM2835_I2C_S_RXD);
}
static uint64_t bcm2835_i2c_read(void *opaque, hwaddr addr, unsigned size)
{
BCM2835I2CState *s = opaque;
uint32_t readval = 0;
switch (addr) {
case BCM2835_I2C_C:
readval = s->c;
break;
case BCM2835_I2C_S:
readval = s->s;
break;
case BCM2835_I2C_DLEN:
readval = s->dlen;
break;
case BCM2835_I2C_A:
readval = s->a;
break;
case BCM2835_I2C_FIFO:
/* We receive I2C messages directly instead of using FIFOs */
if (s->s & BCM2835_I2C_S_TA) {
readval = i2c_recv(s->bus);
s->dlen -= 1;
if (s->dlen == 0) {
bcm2835_i2c_finish_transfer(s);
}
}
bcm2835_i2c_update_interrupt(s);
break;
case BCM2835_I2C_DIV:
readval = s->div;
break;
case BCM2835_I2C_DEL:
readval = s->del;
break;
case BCM2835_I2C_CLKT:
readval = s->clkt;
break;
default:
qemu_log_mask(LOG_GUEST_ERROR,
"%s: Bad offset 0x%" HWADDR_PRIx "\n", __func__, addr);
}
return readval;
}
static void bcm2835_i2c_write(void *opaque, hwaddr addr,
uint64_t value, unsigned int size)
{
BCM2835I2CState *s = opaque;
uint32_t writeval = value;
switch (addr) {
case BCM2835_I2C_C:
/* ST is a one-shot operation; it must read back as 0 */
s->c = writeval & ~BCM2835_I2C_C_ST;
/* Start transfer */
if (writeval & (BCM2835_I2C_C_ST | BCM2835_I2C_C_I2CEN)) {
bcm2835_i2c_begin_transfer(s);
/*
* Handle special case where transfer starts with zero data length.
* Required for zero length i2c quick messages to work.
*/
if (s->dlen == 0) {
bcm2835_i2c_finish_transfer(s);
}
}
bcm2835_i2c_update_interrupt(s);
break;
case BCM2835_I2C_S:
if (writeval & BCM2835_I2C_S_DONE && s->s & BCM2835_I2C_S_DONE) {
/* When DONE is cleared, DLEN should read last written value. */
s->dlen = s->last_dlen;
}
/* Clear DONE, CLKT and ERR by writing 1 */
s->s &= ~(writeval & (BCM2835_I2C_S_DONE |
BCM2835_I2C_S_ERR | BCM2835_I2C_S_CLKT));
break;
case BCM2835_I2C_DLEN:
s->dlen = writeval;
s->last_dlen = writeval;
break;
case BCM2835_I2C_A:
s->a = writeval;
break;
case BCM2835_I2C_FIFO:
/* We send I2C messages directly instead of using FIFOs */
if (s->s & BCM2835_I2C_S_TA) {
if (s->s & BCM2835_I2C_S_TXD) {
if (!i2c_send(s->bus, writeval & 0xff)) {
s->dlen -= 1;
} else {
s->s |= BCM2835_I2C_S_ERR;
}
}
if (s->dlen == 0) {
bcm2835_i2c_finish_transfer(s);
}
}
bcm2835_i2c_update_interrupt(s);
break;
case BCM2835_I2C_DIV:
s->div = writeval;
break;
case BCM2835_I2C_DEL:
s->del = writeval;
break;
case BCM2835_I2C_CLKT:
s->clkt = writeval;
break;
default:
qemu_log_mask(LOG_GUEST_ERROR,
"%s: Bad offset 0x%" HWADDR_PRIx "\n", __func__, addr);
}
}
static const MemoryRegionOps bcm2835_i2c_ops = {
.read = bcm2835_i2c_read,
.write = bcm2835_i2c_write,
.endianness = DEVICE_NATIVE_ENDIAN,
.valid = {
.min_access_size = 4,
.max_access_size = 4,
},
};
static void bcm2835_i2c_realize(DeviceState *dev, Error **errp)
{
BCM2835I2CState *s = BCM2835_I2C(dev);
s->bus = i2c_init_bus(dev, NULL);
memory_region_init_io(&s->iomem, OBJECT(dev), &bcm2835_i2c_ops, s,
TYPE_BCM2835_I2C, 0x24);
sysbus_init_mmio(SYS_BUS_DEVICE(dev), &s->iomem);
sysbus_init_irq(SYS_BUS_DEVICE(dev), &s->irq);
}
static void bcm2835_i2c_reset(DeviceState *dev)
{
BCM2835I2CState *s = BCM2835_I2C(dev);
/* Reset values according to BCM2835 Peripheral Documentation */
s->c = 0x0;
s->s = BCM2835_I2C_S_TXD | BCM2835_I2C_S_TXE;
s->dlen = 0x0;
s->a = 0x0;
s->div = 0x5dc;
s->del = 0x00300030;
s->clkt = 0x40;
}
static const VMStateDescription vmstate_bcm2835_i2c = {
.name = TYPE_BCM2835_I2C,
.version_id = 1,
.minimum_version_id = 1,
.fields = (const VMStateField[]) {
VMSTATE_UINT32(c, BCM2835I2CState),
VMSTATE_UINT32(s, BCM2835I2CState),
VMSTATE_UINT32(dlen, BCM2835I2CState),
VMSTATE_UINT32(a, BCM2835I2CState),
VMSTATE_UINT32(div, BCM2835I2CState),
VMSTATE_UINT32(del, BCM2835I2CState),
VMSTATE_UINT32(clkt, BCM2835I2CState),
VMSTATE_UINT32(last_dlen, BCM2835I2CState),
VMSTATE_END_OF_LIST()
}
};
static void bcm2835_i2c_class_init(ObjectClass *klass, void *data)
{
DeviceClass *dc = DEVICE_CLASS(klass);
device_class_set_legacy_reset(dc, bcm2835_i2c_reset);
dc->realize = bcm2835_i2c_realize;
dc->vmsd = &vmstate_bcm2835_i2c;
}
static const TypeInfo bcm2835_i2c_info = {
.name = TYPE_BCM2835_I2C,
.parent = TYPE_SYS_BUS_DEVICE,
.instance_size = sizeof(BCM2835I2CState),
.class_init = bcm2835_i2c_class_init,
};
static void bcm2835_i2c_register_types(void)
{
type_register_static(&bcm2835_i2c_info);
}
type_init(bcm2835_i2c_register_types)