[Qemu-devel] [PATCH v4 2/2] Add AT24Cxx I2C EEPROM device model

[Jan Kiszka]

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 selecting the exact device type
(required for sizes < 512, the blockdev sector size) or implicitly by
providing a block device image of the corresponding size. 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        |  391 ++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 392 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..654a4e2
--- /dev/null
+++ b/hw/nvram/at24.c
@@ -0,0 +1,391 @@
+/*
+ * 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 {
+    const char *desc;
+    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;
+    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[] = {
+    { "AT24C1 EEPROM",       1*1024,   8, 3, 0, false },
+    { "AT24C2 EEPROM",       2*1024,   8, 3, 0, false },
+    { "AT24C4 EEPROM",       4*1024,  16, 2, 1, false },
+    { "AT24C8 EEPROM",       8*1024,  16, 1, 2, false },
+    { "AT24C16 EEPROM",     16*1024,  16, 0, 3, false },
+    { "AT24C32 EEPROM",     32*1024,  32, 3, 0, true },
+    { "AT24C62 EEPROM",     64*1024,  32, 3, 0, true },
+    { "AT24C128 EEPROM",   128*1024,  64, 2, 0, true },
+    { "AT24C256 EEPROM",   256*1024,  64, 2, 0, true },
+    { "AT24C512 EEPROM",   512*1024, 128, 2, 0, true },
+    { "AT24C1024 EEPROM", 1024*1024, 256, 1, 1, true },
+    { },
+};
+
+static void at24_realize(DeviceState *d, Error **errp)
+{
+    DeviceClass *dc = DEVICE_GET_CLASS(d);
+    I2CSlave *i2c = I2C_SLAVE(d);
+    AT24State *s = AT24(d);
+    const AT24Parameters *params;
+    int64_t image_size;
+    uint32_t 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);
+
+    for (params = at24_parameters; params->size != 0; params++) {
+        if (params->desc == dc->desc) {
+            break;
+        }
+    }
+    size = params->size / 8;
+
+    if (size == 0) {
+        size = image_size;
+
+        for (params = at24_parameters; params->size != 0; params++) {
+            if (size * 8 == params->size) {
+                break;
+            }
+        }
+        if (params->size == 0) {
+            error_setg(errp, "invalid EEPROM size, must be 2^(10..17)");
+            return;
+        }
+    } else if (image_size < size) {
+        error_setg(errp, "image file smaller than EEPROM size");
+        return;
+    }
+
+    s->addr_mask = 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;
+    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_END_OF_LIST(),
+};
+
+static void at24_base_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 (defined by image size)";
+    dc->reset = at24_reset;
+    dc->realize = at24_realize;
+    dc->vmsd = &vmstate_at24;
+    dc->props = at24_properties;
+}
+
+static void at24cxx_class_init(ObjectClass *klass, void *data)
+{
+    DeviceClass *dc = DEVICE_CLASS(klass);
+    const AT24Parameters *params = data;
+
+    dc->desc = params->desc;
+}
+
+#define AT24CXX_TYPE_INFO(type_name, param_no) \
+    { \
+        .name          = (type_name), \
+        .parent        = TYPE_AT24, \
+        .instance_size = sizeof(AT24State), \
+        .class_init    = at24cxx_class_init, \
+        .class_data    = (void *)&at24_parameters[(param_no)], \
+    }
+
+static const TypeInfo at24_info[] = {
+    {
+        .name          = "at24",
+        .parent        = TYPE_I2C_SLAVE,
+        .instance_size = sizeof(AT24State),
+        .class_init    = at24_base_class_init,
+    },
+    AT24CXX_TYPE_INFO("at24c1",     0),
+    AT24CXX_TYPE_INFO("at24c2",     1),
+    AT24CXX_TYPE_INFO("at24c4",     2),
+    AT24CXX_TYPE_INFO("at24c8",     3),
+    AT24CXX_TYPE_INFO("at24c16",    4),
+    AT24CXX_TYPE_INFO("at24c32",    5),
+    AT24CXX_TYPE_INFO("at24c64",    6),
+    AT24CXX_TYPE_INFO("at24c128",   7),
+    AT24CXX_TYPE_INFO("at24c256",   8),
+    AT24CXX_TYPE_INFO("at24c512",   9),
+    AT24CXX_TYPE_INFO("at24c1024", 10),
+};
+
+static void at24_register_types(void)
+{
+    unsigned int n;
+
+    /* buffering is based on this, enforce it early */
+    assert(AT24_MAX_PAGE_LEN <= BDRV_SECTOR_SIZE);
+
+    for (n = 0; n < ARRAY_SIZE(at24_info); n++) {
+        type_register_static(&at24_info[n]);
+    }
+}
+
+type_init(at24_register_types)
-- 
1.7.3.4