diff options
Diffstat (limited to 'hw/i2c/bcm2835_i2c.c')
| -rw-r--r-- | hw/i2c/bcm2835_i2c.c | 282 |
1 files changed, 282 insertions, 0 deletions
diff --git a/hw/i2c/bcm2835_i2c.c b/hw/i2c/bcm2835_i2c.c new file mode 100644 index 0000000000..20ec46eeab --- /dev/null +++ b/hw/i2c/bcm2835_i2c.c @@ -0,0 +1,282 @@ +/* + * 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); + + dc->reset = 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) |