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* QEMU model of the Milkymist SD Card Controller.
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* Copyright (c) 2010 Michael Walle <michael@walle.cc>
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2 of the License, or (at your option) any later version.
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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* You should have received a copy of the GNU Lesser General Public
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* License along with this library; if not, see <http://www.gnu.org/licenses/>.
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* Specification available at:
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* http://www.milkymist.org/socdoc/memcard.pdf
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#include "hw/sysbus.h"
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#include "sysemu/sysemu.h"
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#include "qemu/error-report.h"
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#include "sysemu/blockdev.h"
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ENABLE_CMD_TX = (1<<0),
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ENABLE_CMD_RX = (1<<1),
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ENABLE_DAT_TX = (1<<2),
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ENABLE_DAT_RX = (1<<3),
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PENDING_CMD_TX = (1<<0),
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PENDING_CMD_RX = (1<<1),
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PENDING_DAT_TX = (1<<2),
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PENDING_DAT_RX = (1<<3),
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START_CMD_TX = (1<<0),
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START_DAT_RX = (1<<1),
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struct MilkymistMemcardState {
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MemoryRegion regs_region;
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int command_write_ptr;
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int response_read_ptr;
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typedef struct MilkymistMemcardState MilkymistMemcardState;
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static void update_pending_bits(MilkymistMemcardState *s)
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/* transmits are instantaneous, thus tx pending bits are never set */
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s->regs[R_PENDING] = 0;
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/* if rx is enabled the corresponding pending bits are always set */
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if (s->regs[R_ENABLE] & ENABLE_CMD_RX) {
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s->regs[R_PENDING] |= PENDING_CMD_RX;
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if (s->regs[R_ENABLE] & ENABLE_DAT_RX) {
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s->regs[R_PENDING] |= PENDING_DAT_RX;
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static void memcard_sd_command(MilkymistMemcardState *s)
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req.cmd = s->command[0] & 0x3f;
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req.arg = (s->command[1] << 24) | (s->command[2] << 16)
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| (s->command[3] << 8) | s->command[4];
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req.crc = s->command[5];
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s->response[0] = req.cmd;
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s->response_len = sd_do_command(s->card, &req, s->response+1);
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s->response_read_ptr = 0;
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if (s->response_len == 16) {
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s->response[0] = 0x3f;
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s->response_len += 1;
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} else if (s->response_len == 4) {
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/* no crc calculation, insert dummy byte */
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s->response_len += 2;
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/* next write is a dummy byte to clock the initialization of the sd
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s->ignore_next_cmd = 1;
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static uint64_t memcard_read(void *opaque, hwaddr addr,
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MilkymistMemcardState *s = opaque;
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r = s->response[s->response_read_ptr++];
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if (s->response_read_ptr > s->response_len) {
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error_report("milkymist_memcard: "
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"read more cmd bytes than available. Clipping.");
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s->response_read_ptr = 0;
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r |= sd_read_data(s->card) << 24;
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r |= sd_read_data(s->card) << 16;
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r |= sd_read_data(s->card) << 8;
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r |= sd_read_data(s->card);
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error_report("milkymist_memcard: read access to unknown register 0x"
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TARGET_FMT_plx, addr << 2);
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trace_milkymist_memcard_memory_read(addr << 2, r);
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static void memcard_write(void *opaque, hwaddr addr, uint64_t value,
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MilkymistMemcardState *s = opaque;
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trace_milkymist_memcard_memory_write(addr, value);
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/* clear rx pending bits */
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s->regs[R_PENDING] &= ~(value & (PENDING_CMD_RX | PENDING_DAT_RX));
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update_pending_bits(s);
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if (s->ignore_next_cmd) {
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s->ignore_next_cmd = 0;
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s->command[s->command_write_ptr] = value & 0xff;
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s->command_write_ptr = (s->command_write_ptr + 1) % 6;
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if (s->command_write_ptr == 0) {
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memcard_sd_command(s);
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sd_write_data(s->card, (value >> 24) & 0xff);
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sd_write_data(s->card, (value >> 16) & 0xff);
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sd_write_data(s->card, (value >> 8) & 0xff);
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sd_write_data(s->card, value & 0xff);
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s->regs[addr] = value;
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update_pending_bits(s);
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s->regs[addr] = value;
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error_report("milkymist_memcard: write access to unknown register 0x"
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TARGET_FMT_plx, addr << 2);
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static const MemoryRegionOps memcard_mmio_ops = {
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.read = memcard_read,
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.write = memcard_write,
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.min_access_size = 4,
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.max_access_size = 4,
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.endianness = DEVICE_NATIVE_ENDIAN,
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static void milkymist_memcard_reset(DeviceState *d)
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MilkymistMemcardState *s =
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container_of(d, MilkymistMemcardState, busdev.qdev);
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s->command_write_ptr = 0;
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s->response_read_ptr = 0;
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for (i = 0; i < R_MAX; i++) {
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static int milkymist_memcard_init(SysBusDevice *dev)
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MilkymistMemcardState *s = FROM_SYSBUS(typeof(*s), dev);
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dinfo = drive_get_next(IF_SD);
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s->card = sd_init(dinfo ? dinfo->bdrv : NULL, 0);
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s->enabled = dinfo ? bdrv_is_inserted(dinfo->bdrv) : 0;
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memory_region_init_io(&s->regs_region, &memcard_mmio_ops, s,
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"milkymist-memcard", R_MAX * 4);
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sysbus_init_mmio(dev, &s->regs_region);
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static const VMStateDescription vmstate_milkymist_memcard = {
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.name = "milkymist-memcard",
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.minimum_version_id = 1,
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.minimum_version_id_old = 1,
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.fields = (VMStateField[]) {
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VMSTATE_INT32(command_write_ptr, MilkymistMemcardState),
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VMSTATE_INT32(response_read_ptr, MilkymistMemcardState),
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VMSTATE_INT32(response_len, MilkymistMemcardState),
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VMSTATE_INT32(ignore_next_cmd, MilkymistMemcardState),
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VMSTATE_INT32(enabled, MilkymistMemcardState),
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VMSTATE_UINT8_ARRAY(command, MilkymistMemcardState, 6),
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VMSTATE_UINT8_ARRAY(response, MilkymistMemcardState, 17),
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VMSTATE_UINT32_ARRAY(regs, MilkymistMemcardState, R_MAX),
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VMSTATE_END_OF_LIST()
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static void milkymist_memcard_class_init(ObjectClass *klass, void *data)
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DeviceClass *dc = DEVICE_CLASS(klass);
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SysBusDeviceClass *k = SYS_BUS_DEVICE_CLASS(klass);
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k->init = milkymist_memcard_init;
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dc->reset = milkymist_memcard_reset;
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dc->vmsd = &vmstate_milkymist_memcard;
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static const TypeInfo milkymist_memcard_info = {
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.name = "milkymist-memcard",
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.parent = TYPE_SYS_BUS_DEVICE,
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.instance_size = sizeof(MilkymistMemcardState),
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.class_init = milkymist_memcard_class_init,
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static void milkymist_memcard_register_types(void)
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type_register_static(&milkymist_memcard_info);
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type_init(milkymist_memcard_register_types)