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Re: [Qemu-devel] [PATCH v3 2/2] Add AT24Cxx I2C EEPROM device model
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From: |
Peter Crosthwaite |
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Subject: |
Re: [Qemu-devel] [PATCH v3 2/2] Add AT24Cxx I2C EEPROM device model |
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Date: |
Fri, 26 Apr 2013 22:16:34 +1000 |
Hi Jan,
On Fri, Apr 26, 2013 at 7:19 PM, Jan Kiszka <address@hidden> wrote:
> This implements I2C EEPROMs of the AT24Cxx series. Sizes from 1Kbit to
> 1024Kbit are supported. Each EEPROM is backed by a block device. Its
> size can be explicitly specified by the "size" property (required for
> sizes < 512, the blockdev sector size) or is derived from the size of
> the backing block device. Device addresses are built from the device
> number property. Write protection can be configured by declaring the
> block device read-only.
>
> Signed-off-by: Jan Kiszka <address@hidden>
> ---
> hw/nvram/Makefile.objs | 2 +-
> hw/nvram/at24.c | 347
> ++++++++++++++++++++++++++++++++++++++++++++++++
> 2 files changed, 348 insertions(+), 1 deletions(-)
> create mode 100644 hw/nvram/at24.c
>
> diff --git a/hw/nvram/Makefile.objs b/hw/nvram/Makefile.objs
> index e9a6694..8271cd6 100644
> --- a/hw/nvram/Makefile.objs
> +++ b/hw/nvram/Makefile.objs
> @@ -1,5 +1,5 @@
> common-obj-$(CONFIG_DS1225Y) += ds1225y.o
> -common-obj-y += eeprom93xx.o
> +common-obj-y += eeprom93xx.o at24.o
> common-obj-y += fw_cfg.o
> common-obj-$(CONFIG_MAC_NVRAM) += mac_nvram.o
> obj-$(CONFIG_PSERIES) += spapr_nvram.o
> diff --git a/hw/nvram/at24.c b/hw/nvram/at24.c
> new file mode 100644
> index 0000000..91e58e0
> --- /dev/null
> +++ b/hw/nvram/at24.c
> @@ -0,0 +1,347 @@
> +/*
> + * AT24Cxx EEPROM emulation
> + *
> + * Copyright (c) Siemens AG, 2012, 2013
> + * Author: Jan Kiszka
> + *
> + * 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 "hw/hw.h"
> +#include "hw/i2c/i2c.h"
> +#include "hw/block/block.h"
> +#include "sysemu/blockdev.h"
> +
> +#define TYPE_AT24 "at24"
> +#define AT24(obj) OBJECT_CHECK(AT24State, (obj), TYPE_AT24)
> +
> +#define AT24_BASE_ADDRESS 0x50
> +#define AT24_MAX_PAGE_LEN 256
> +
> +typedef struct AT24Parameters {
> + unsigned int size;
> + unsigned int page_size;
> + unsigned int device_bits;
> + unsigned int hi_addr_bits;
> + bool addr16;
> +} AT24Parameters;
> +
> +typedef enum AT24TransferState {
> + AT24_IDLE,
> + AT24_RD_ADDR,
> + AT24_WR_ADDR_HI,
> + AT24_WR_ADDR_LO,
> + AT24_RW_DATA0,
> + AT24_RD_DATA,
> + AT24_WR_DATA,
> +} AT24TransferState;
> +
> +typedef struct AT24State {
> + I2CSlave parent_obj;
> +
> + BlockConf block_conf;
> + BlockDriverState *bs;
> + uint32_t size;
> + bool wp;
> + unsigned int addr_mask;
> + unsigned int page_mask;
> + bool addr16;
> + unsigned int hi_addr_mask;
> + uint8_t device;
> + AT24TransferState transfer_state;
> + uint8_t sector_buffer[BDRV_SECTOR_SIZE];
> + int cached_sector;
> + bool cache_dirty;
> + uint32_t transfer_addr;
> +} AT24State;
> +
> +static void at24_flush_transfer_buffer(AT24State *s)
> +{
> + if (s->cached_sector < 0 || !s->cache_dirty) {
> + return;
> + }
> + bdrv_write(s->bs, s->cached_sector, s->sector_buffer, 1);
> + s->cache_dirty = false;
> +}
> +
> +static void at24_event(I2CSlave *i2c, enum i2c_event event, uint8_t param)
> +{
> + AT24State *s = AT24(i2c);
> +
> + switch (event) {
> + case I2C_START_SEND:
> + switch (s->transfer_state) {
> + case AT24_IDLE:
> + if (s->addr16) {
> + s->transfer_addr = (param & s->hi_addr_mask) << 16;
> + s->transfer_state = AT24_WR_ADDR_HI;
> + } else {
> + s->transfer_addr = (param & s->hi_addr_mask) << 8;
> + s->transfer_state = AT24_WR_ADDR_LO;
> + }
> + break;
> + default:
> + s->transfer_state = AT24_IDLE;
> + break;
> + }
> + break;
> + case I2C_START_RECV:
> + switch (s->transfer_state) {
> + case AT24_IDLE:
> + s->transfer_state = AT24_RD_ADDR;
> + break;
> + case AT24_RW_DATA0:
> + s->transfer_state = AT24_RD_DATA;
> + break;
> + default:
> + s->transfer_state = AT24_IDLE;
> + break;
> + }
> + break;
> + case I2C_FINISH:
> + switch (s->transfer_state) {
> + case AT24_WR_DATA:
> + at24_flush_transfer_buffer(s);
> + /* fall through */
> + default:
> + s->transfer_state = AT24_IDLE;
> + break;
> + }
> + break;
> + default:
> + s->transfer_state = AT24_IDLE;
> + break;
> + }
> +}
> +
> +static int at24_cache_sector(AT24State *s, int sector)
> +{
> + int ret;
> +
> + if (s->cached_sector == sector) {
> + return 0;
> + }
> + ret = bdrv_read(s->bs, sector, s->sector_buffer, 1);
> + if (ret < 0) {
> + s->cached_sector = -1;
> + return ret;
> + }
> + s->cached_sector = sector;
> + s->cache_dirty = false;
> + return 0;
> +}
> +
> +static int at24_tx(I2CSlave *i2c, uint8_t data)
> +{
> + AT24State *s = AT24(i2c);
> +
> + switch (s->transfer_state) {
> + case AT24_WR_ADDR_HI:
> + s->transfer_addr |= (data << 8) & s->addr_mask;
> + s->transfer_state = AT24_WR_ADDR_LO;
> + break;
> + case AT24_WR_ADDR_LO:
> + s->transfer_addr |= data & s->addr_mask;
> + s->transfer_state = AT24_RW_DATA0;
> + break;
> + case AT24_RW_DATA0:
> + s->transfer_state = AT24_WR_DATA;
> + if (at24_cache_sector(s, s->transfer_addr >> BDRV_SECTOR_BITS) < 0) {
> + s->transfer_state = AT24_IDLE;
> + return -1;
> + }
> + /* fall through */
> + case AT24_WR_DATA:
> + if (!s->wp) {
> + s->sector_buffer[s->transfer_addr & ~BDRV_SECTOR_MASK] = data;
> + s->cache_dirty = true;
> + }
> + s->transfer_addr = (s->transfer_addr & s->page_mask) |
> + ((s->transfer_addr + 1) & ~s->page_mask);
> + break;
> + default:
> + s->transfer_state = AT24_IDLE;
> + return -1;
> + }
> + return 0;
> +}
> +
> +static int at24_rx(I2CSlave *i2c)
> +{
> + AT24State *s = AT24(i2c);
> + unsigned int sector, offset;
> + int result;
> +
> + switch (s->transfer_state) {
> + case AT24_RD_ADDR:
> + s->transfer_state = AT24_IDLE;
> + result = s->transfer_addr;
> + break;
> + case AT24_RD_DATA:
> + sector = s->transfer_addr >> BDRV_SECTOR_BITS;
> + offset = s->transfer_addr & ~BDRV_SECTOR_MASK;
> + s->transfer_addr = (s->transfer_addr + 1) & s->addr_mask;
> + if (at24_cache_sector(s, sector) < 0) {
> + result = 0;
> + break;
> + }
> + result = s->sector_buffer[offset];
> + break;
> + default:
> + s->transfer_state = AT24_IDLE;
> + result = 0;
> + break;
> + }
> + return result;
> +}
> +
> +static void at24_reset(DeviceState *d)
> +{
> + AT24State *s = AT24(d);
> +
> + s->transfer_state = AT24_IDLE;
> + s->cached_sector = -1;
> +}
> +
> +static const AT24Parameters at24_parameters[] = {
> + { 1*1024, 8, 3, 0, false },
> + { 2*1024, 8, 3, 0, false },
> + { 4*1024, 16, 2, 1, false },
> + { 8*1024, 16, 1, 2, false },
> + { 16*1024, 16, 0, 3, false },
> + { 32*1024, 32, 3, 0, true },
> + { 64*1024, 32, 3, 0, true },
> + { 128*1024, 64, 2, 0, true },
> + { 256*1024, 64, 2, 0, true },
> + { 512*1024, 128, 2, 0, true },
> + { 1024*1024, 256, 1, 1, true },
> + { },
You could potentially add a string field to this array for the part
name. "at24c08" etc.
Then in the register types function you can iterate through the array
and instantiate a
type for each different part. This would allow you to go
qemu-system-foo -device at24c08
rather than
qemu-system-foo -device at24cXX,size=4096
etc.
See block/m25p80.c for a similar situation.
> +};
> +
> +static void at24_realize(DeviceState *d, Error **errp)
> +{
> + I2CSlave *i2c = I2C_SLAVE(d);
> + AT24State *s = AT24(d);
> + const AT24Parameters *params;
> + int64_t image_size;
> + int dev_no;
> +
> + s->bs = s->block_conf.bs;
> + if (!s->bs) {
> + error_setg(errp, "drive property not set");
> + return;
> + }
> +
> + s->wp = bdrv_is_read_only(s->bs);
> +
> + image_size = bdrv_getlength(s->bs);
> + if (s->size == 0) {
> + s->size = image_size;
> + } else if (image_size < s->size) {
> + error_setg(errp, "image file smaller than specified EEPROM size");
> + return;
> + }
> +
> + for (params = at24_parameters; params->size != 0; params++) {
> + if (s->size * 8 == params->size) {
> + break;
> + }
> + }
> + if (params->size == 0) {
> + error_setg(errp, "invalid EEPROM size, must be 2^(10..17)");
> + return;
> + }
> + s->addr_mask = s->size - 1;
> + s->page_mask = ~(params->page_size - 1);
> + s->hi_addr_mask = (1 << params->hi_addr_bits) - 1;
> + s->addr16 = params->addr16;
> +
> + dev_no = (s->device & ((1 << params->device_bits) - 1)) <<
> + params->hi_addr_bits;
I still think this device bits has a place in the I2C layer itself.
But i'm happy to send
cleanup patches myself after a merge. I need this for another I2C
device and rather
not copy paste.
Regards,
Peter
> + i2c_set_slave_address(i2c, AT24_BASE_ADDRESS | dev_no);
> + i2c_set_slave_address_mask(i2c, 0x7f & ~s->hi_addr_mask);
> +}
> +
> +static void at24_pre_save(void *opaque)
> +{
> + AT24State *s = opaque;
> +
> + at24_flush_transfer_buffer(s);
> +}
> +
> +static int at24_post_load(void *opaque, int version_id)
> +{
> + AT24State *s = opaque;
> +
> + s->cached_sector = -1;
> + return 0;
> +}
> +
> +static const VMStateDescription vmstate_at24 = {
> + .name = "at24",
> + .version_id = 1,
> + .minimum_version_id = 1,
> + .minimum_version_id_old = 1,
> + .pre_save = at24_pre_save,
> + .post_load = at24_post_load,
> + .fields = (VMStateField[]) {
> + VMSTATE_UINT32(transfer_state, AT24State),
> + VMSTATE_UINT32(transfer_addr, AT24State),
> + VMSTATE_END_OF_LIST()
> + }
> +};
> +
> +static Property at24_properties[] = {
> + DEFINE_BLOCK_PROPERTIES(AT24State, block_conf),
> + DEFINE_PROP_UINT8("device", AT24State, device, 0),
> + DEFINE_PROP_UINT32("size", AT24State, size, 0),
> + DEFINE_PROP_END_OF_LIST(),
> +};
> +
> +static void at24_class_init(ObjectClass *klass, void *data)
> +{
> + DeviceClass *dc = DEVICE_CLASS(klass);
> + I2CSlaveClass *sc = I2C_SLAVE_CLASS(klass);
> +
> + sc->event = at24_event;
> + sc->recv = at24_rx;
> + sc->send = at24_tx;
> + dc->desc = "AT24Cxx EEPROM";
> + dc->reset = at24_reset;
> + dc->realize = at24_realize;
> + dc->vmsd = &vmstate_at24;
> + dc->props = at24_properties;
> +}
> +
> +static const TypeInfo at24_info = {
> + .name = "at24",
> + .parent = TYPE_I2C_SLAVE,
> + .instance_size = sizeof(AT24State),
> + .class_init = at24_class_init,
> +};
> +
> +static void at24_register_types(void)
> +{
> + /* buffering is based on this, enforce it early */
> + assert(AT24_MAX_PAGE_LEN <= BDRV_SECTOR_SIZE);
> +
> + type_register_static(&at24_info);
> +}
> +
> +type_init(at24_register_types)
> --
> 1.7.3.4
>
>