diff mbox series

[v4,3/5] hw/nvram/eeprom_at24c: Add init_rom field and at24c_eeprom_init_rom helper

Message ID 20230118024214.14413-4-peter@pjd.dev
State New
Headers show
Series hw/nvram/eeprom_at24c: Cleanup + FRUID EEPROM init example | expand

Commit Message

Peter Delevoryas Jan. 18, 2023, 2:42 a.m. UTC 
Allows users to specify binary data to initialize an EEPROM, allowing users to
emulate data programmed at manufacturing time.

- Added init_rom and init_rom_size attributes to TYPE_AT24C_EE
- Added at24c_eeprom_init_rom helper function to initialize attributes
- If -drive property is provided, it overrides init_rom data

Signed-off-by: Peter Delevoryas <peter@pjd.dev>
Reviewed-by: Joel Stanley <joel@jms.id.au>
---
 hw/nvram/eeprom_at24c.c         | 37 ++++++++++++++++++++++++++++-----
 include/hw/nvram/eeprom_at24c.h | 16 ++++++++++++++
 2 files changed, 48 insertions(+), 5 deletions(-)

Comments

Cédric Le Goater Jan. 18, 2023, 12:32 p.m. UTC | #1 
On 1/18/23 03:42, Peter Delevoryas wrote:
> Allows users to specify binary data to initialize an EEPROM, allowing users to
> emulate data programmed at manufacturing time.
> 
> - Added init_rom and init_rom_size attributes to TYPE_AT24C_EE
> - Added at24c_eeprom_init_rom helper function to initialize attributes
> - If -drive property is provided, it overrides init_rom data
> 
> Signed-off-by: Peter Delevoryas <peter@pjd.dev>
> Reviewed-by: Joel Stanley <joel@jms.id.au>

Reviewed-by: Cédric Le Goater <clg@kaod.org>

Thanks,

C.

> ---
>   hw/nvram/eeprom_at24c.c         | 37 ++++++++++++++++++++++++++++-----
>   include/hw/nvram/eeprom_at24c.h | 16 ++++++++++++++
>   2 files changed, 48 insertions(+), 5 deletions(-)
> 
> diff --git a/hw/nvram/eeprom_at24c.c b/hw/nvram/eeprom_at24c.c
> index 98857e3626b9..f8d751fa278d 100644
> --- a/hw/nvram/eeprom_at24c.c
> +++ b/hw/nvram/eeprom_at24c.c
> @@ -50,6 +50,9 @@ struct EEPROMState {
>       uint8_t *mem;
>   
>       BlockBackend *blk;
> +
> +    const uint8_t *init_rom;
> +    uint32_t init_rom_size;
>   };
>   
>   static
> @@ -131,19 +134,38 @@ int at24c_eeprom_send(I2CSlave *s, uint8_t data)
>   
>   I2CSlave *at24c_eeprom_init(I2CBus *bus, uint8_t address, uint32_t rom_size)
>   {
> -    I2CSlave *i2c_dev = i2c_slave_new(TYPE_AT24C_EE, address);
> -    DeviceState *dev = DEVICE(i2c_dev);
> +    return at24c_eeprom_init_rom(bus, address, rom_size, NULL, 0);
> +}
> +
> +I2CSlave *at24c_eeprom_init_rom(I2CBus *bus, uint8_t address, uint32_t rom_size,
> +                                const uint8_t *init_rom, uint32_t init_rom_size)
> +{
> +    EEPROMState *s;
> +
> +    s = AT24C_EE(qdev_new(TYPE_AT24C_EE));
> +
> +    qdev_prop_set_uint8(DEVICE(s), "address", address);
> +    qdev_prop_set_uint32(DEVICE(s), "rom-size", rom_size);
>   
> -    qdev_prop_set_uint32(dev, "rom-size", rom_size);
> -    i2c_slave_realize_and_unref(i2c_dev, bus, &error_abort);
> +    /* TODO: Model init_rom with QOM properties. */
> +    s->init_rom = init_rom;
> +    s->init_rom_size = init_rom_size;
>   
> -    return i2c_dev;
> +    i2c_slave_realize_and_unref(I2C_SLAVE(s), bus, &error_abort);
> +
> +    return I2C_SLAVE(s);
>   }
>   
>   static void at24c_eeprom_realize(DeviceState *dev, Error **errp)
>   {
>       EEPROMState *ee = AT24C_EE(dev);
>   
> +    if (ee->init_rom_size > ee->rsize) {
> +        error_setg(errp, "%s: init rom is larger than rom: %u > %u",
> +                   TYPE_AT24C_EE, ee->init_rom_size, ee->rsize);
> +        return;
> +    }
> +
>       if (ee->blk) {
>           int64_t len = blk_getlength(ee->blk);
>   
> @@ -163,6 +185,7 @@ static void at24c_eeprom_realize(DeviceState *dev, Error **errp)
>       }
>   
>       ee->mem = g_malloc0(ee->rsize);
> +
>   }
>   
>   static
> @@ -176,6 +199,10 @@ void at24c_eeprom_reset(DeviceState *state)
>   
>       memset(ee->mem, 0, ee->rsize);
>   
> +    if (ee->init_rom) {
> +        memcpy(ee->mem, ee->init_rom, MIN(ee->init_rom_size, ee->rsize));
> +    }
> +
>       if (ee->blk) {
>           int ret = blk_pread(ee->blk, 0, ee->rsize, ee->mem, 0);
>   
> diff --git a/include/hw/nvram/eeprom_at24c.h b/include/hw/nvram/eeprom_at24c.h
> index 196db309d451..acb9857b2add 100644
> --- a/include/hw/nvram/eeprom_at24c.h
> +++ b/include/hw/nvram/eeprom_at24c.h
> @@ -20,4 +20,20 @@
>    */
>   I2CSlave *at24c_eeprom_init(I2CBus *bus, uint8_t address, uint32_t rom_size);
>   
> +
> +/*
> + * Create and realize an AT24C EEPROM device on the heap with initial data.
> + * @bus: I2C bus to put it on
> + * @address: I2C address of the EEPROM slave when put on a bus
> + * @rom_size: size of the EEPROM
> + * @init_rom: Array of bytes to initialize EEPROM memory with
> + * @init_rom_size: Size of @init_rom, must be less than or equal to @rom_size
> + *
> + * Create the device state structure, initialize it, put it on the specified
> + * @bus, and drop the reference to it (the device is realized). Copies the data
> + * from @init_rom to the beginning of the EEPROM memory buffer.
> + */
> +I2CSlave *at24c_eeprom_init_rom(I2CBus *bus, uint8_t address, uint32_t rom_size,
> +                                const uint8_t *init_rom, uint32_t init_rom_size);
> +
>   #endif
Peter Delevoryas Jan. 25, 2023, 7:12 p.m. UTC | #2 
On Wed, Jan 25, 2023 at 04:53:20PM +0000, Ninad S Palsule wrote:
> Signed-off-by: Peter Delevoryas peter@pjd.dev<mailto:peter@pjd.dev>
> Reviewed-by: Joel Stanley joel@jms.id.au<mailto:joel@jms.id.au>
> 
> Tested-by: Ninad Palsule ninadpalsule@us.ibm.com<mailto:ninadpalsule@us.ibm.com>
> 
> Hi Peter,
> I applied your patches and made sure that different EEPROM images can be loaded from
> appropriate image files and it is working as expected.

Thanks Ninad, this is a good regression test to make sure I didn't break the
existing drive proprerty.

- Peter

> 
> # Used following command to invoke the qemu.
> qemu-system-arm -M rainier-bmc -nographic \
>   -kernel fitImage-linux.bin \
>   -dtb aspeed-bmc-ibm-rainier.dtb \
>   -initrd obmc-phosphor-initramfs.rootfs.cpio.xz \
>   -drive file=obmc-phosphor-image.rootfs.wic.qcow2,if=sd,index=2 \
>   -append "rootwait console=ttyS4,115200n8 root=PARTLABEL=rofs-a" \
>   -device at24c-eeprom,bus=aspeed.i2c.bus.0,address=0x51,drive=a,rom-size=32768 -drive file=tpm.eeprom.bin,format=raw,if=none,id=a \
>   -device at24c-eeprom,bus=aspeed.i2c.bus.7,address=0x50,drive=b,rom-size=65536 -drive file=oppanel.eeprom.bin,format=raw,if=none,id=b \
>   -device at24c-eeprom,bus=aspeed.i2c.bus.7,address=0x51,drive=c,rom-size=65536 -drive file=lcd.eeprom.bin,format=raw,if=none,id=c \
>   -device at24c-eeprom,bus=aspeed.i2c.bus.8,address=0x50,drive=d,rom-size=65536 -drive file=baseboard.eeprom.bin,format=raw,if=none,id=d \
>   -device at24c-eeprom,bus=aspeed.i2c.bus.8,address=0x51,drive=e,rom-size=65536 -drive file=bmc.eeprom.bin,format=raw,if=none,id=e \
>   -device at24c-eeprom,bus=aspeed.i2c.bus.9,address=0x50,drive=f,rom-size=131072 -drive file=vrm.eeprom.bin,format=raw,if=none,id=f \
>   -device at24c-eeprom,bus=aspeed.i2c.bus.10,address=0x50,drive=g,rom-size=131072 -drive file=vrm.eeprom.bin,format=raw,if=none,id=g \
>   -device at24c-eeprom,bus=aspeed.i2c.bus.13,address=0x50,drive=h,rom-size=65536 -drive file=nvme.eeprom.bin,format=raw,if=none,id=h \
>   -device at24c-eeprom,bus=aspeed.i2c.bus.14,address=0x50,drive=i,rom-size=65536 -drive file=nvme.eeprom.bin,format=raw,if=none,id=i \
>   -device at24c-eeprom,bus=aspeed.i2c.bus.15,address=0x50,drive=j,rom-size=65536 -drive file=nvme.eeprom.bin,format=raw,if=none,id=j
Corey Minyard Jan. 25, 2023, 9:36 p.m. UTC | #3 
On Tue, Jan 17, 2023 at 06:42:12PM -0800, Peter Delevoryas wrote:
> Allows users to specify binary data to initialize an EEPROM, allowing users to
> emulate data programmed at manufacturing time.
> 
> - Added init_rom and init_rom_size attributes to TYPE_AT24C_EE
> - Added at24c_eeprom_init_rom helper function to initialize attributes
> - If -drive property is provided, it overrides init_rom data
> 
> Signed-off-by: Peter Delevoryas <peter@pjd.dev>
> Reviewed-by: Joel Stanley <joel@jms.id.au>
> ---
>  hw/nvram/eeprom_at24c.c         | 37 ++++++++++++++++++++++++++++-----
>  include/hw/nvram/eeprom_at24c.h | 16 ++++++++++++++
>  2 files changed, 48 insertions(+), 5 deletions(-)
> 
> diff --git a/hw/nvram/eeprom_at24c.c b/hw/nvram/eeprom_at24c.c
> index 98857e3626b9..f8d751fa278d 100644
> --- a/hw/nvram/eeprom_at24c.c
> +++ b/hw/nvram/eeprom_at24c.c
> @@ -50,6 +50,9 @@ struct EEPROMState {
>      uint8_t *mem;
>  
>      BlockBackend *blk;
> +
> +    const uint8_t *init_rom;
> +    uint32_t init_rom_size;
>  };
>  
>  static
> @@ -131,19 +134,38 @@ int at24c_eeprom_send(I2CSlave *s, uint8_t data)
>  
>  I2CSlave *at24c_eeprom_init(I2CBus *bus, uint8_t address, uint32_t rom_size)
>  {
> -    I2CSlave *i2c_dev = i2c_slave_new(TYPE_AT24C_EE, address);
> -    DeviceState *dev = DEVICE(i2c_dev);
> +    return at24c_eeprom_init_rom(bus, address, rom_size, NULL, 0);
> +}
> +
> +I2CSlave *at24c_eeprom_init_rom(I2CBus *bus, uint8_t address, uint32_t rom_size,
> +                                const uint8_t *init_rom, uint32_t init_rom_size)
> +{
> +    EEPROMState *s;
> +
> +    s = AT24C_EE(qdev_new(TYPE_AT24C_EE));
> +
> +    qdev_prop_set_uint8(DEVICE(s), "address", address);

Why did you switch from using i2c_slave_new()?  Using it is more
documentation and future-proofing than convenience.

Other than that, looks good to me.

Reviewed-by: Corey Minyard <cminyard@mvista.com>

> +    qdev_prop_set_uint32(DEVICE(s), "rom-size", rom_size);
>  
> -    qdev_prop_set_uint32(dev, "rom-size", rom_size);
> -    i2c_slave_realize_and_unref(i2c_dev, bus, &error_abort);
> +    /* TODO: Model init_rom with QOM properties. */
> +    s->init_rom = init_rom;
> +    s->init_rom_size = init_rom_size;
>  
> -    return i2c_dev;
> +    i2c_slave_realize_and_unref(I2C_SLAVE(s), bus, &error_abort);
> +
> +    return I2C_SLAVE(s);
>  }
>  
>  static void at24c_eeprom_realize(DeviceState *dev, Error **errp)
>  {
>      EEPROMState *ee = AT24C_EE(dev);
>  
> +    if (ee->init_rom_size > ee->rsize) {
> +        error_setg(errp, "%s: init rom is larger than rom: %u > %u",
> +                   TYPE_AT24C_EE, ee->init_rom_size, ee->rsize);
> +        return;
> +    }
> +
>      if (ee->blk) {
>          int64_t len = blk_getlength(ee->blk);
>  
> @@ -163,6 +185,7 @@ static void at24c_eeprom_realize(DeviceState *dev, Error **errp)
>      }
>  
>      ee->mem = g_malloc0(ee->rsize);
> +
>  }
>  
>  static
> @@ -176,6 +199,10 @@ void at24c_eeprom_reset(DeviceState *state)
>  
>      memset(ee->mem, 0, ee->rsize);
>  
> +    if (ee->init_rom) {
> +        memcpy(ee->mem, ee->init_rom, MIN(ee->init_rom_size, ee->rsize));
> +    }
> +
>      if (ee->blk) {
>          int ret = blk_pread(ee->blk, 0, ee->rsize, ee->mem, 0);
>  
> diff --git a/include/hw/nvram/eeprom_at24c.h b/include/hw/nvram/eeprom_at24c.h
> index 196db309d451..acb9857b2add 100644
> --- a/include/hw/nvram/eeprom_at24c.h
> +++ b/include/hw/nvram/eeprom_at24c.h
> @@ -20,4 +20,20 @@
>   */
>  I2CSlave *at24c_eeprom_init(I2CBus *bus, uint8_t address, uint32_t rom_size);
>  
> +
> +/*
> + * Create and realize an AT24C EEPROM device on the heap with initial data.
> + * @bus: I2C bus to put it on
> + * @address: I2C address of the EEPROM slave when put on a bus
> + * @rom_size: size of the EEPROM
> + * @init_rom: Array of bytes to initialize EEPROM memory with
> + * @init_rom_size: Size of @init_rom, must be less than or equal to @rom_size
> + *
> + * Create the device state structure, initialize it, put it on the specified
> + * @bus, and drop the reference to it (the device is realized). Copies the data
> + * from @init_rom to the beginning of the EEPROM memory buffer.
> + */
> +I2CSlave *at24c_eeprom_init_rom(I2CBus *bus, uint8_t address, uint32_t rom_size,
> +                                const uint8_t *init_rom, uint32_t init_rom_size);
> +
>  #endif
> -- 
> 2.39.0
> 
>
Peter Delevoryas Jan. 25, 2023, 10:06 p.m. UTC | #4 
On Wed, Jan 25, 2023 at 03:36:23PM -0600, Corey Minyard wrote:
> On Tue, Jan 17, 2023 at 06:42:12PM -0800, Peter Delevoryas wrote:
> > Allows users to specify binary data to initialize an EEPROM, allowing users to
> > emulate data programmed at manufacturing time.
> > 
> > - Added init_rom and init_rom_size attributes to TYPE_AT24C_EE
> > - Added at24c_eeprom_init_rom helper function to initialize attributes
> > - If -drive property is provided, it overrides init_rom data
> > 
> > Signed-off-by: Peter Delevoryas <peter@pjd.dev>
> > Reviewed-by: Joel Stanley <joel@jms.id.au>
> > ---
> >  hw/nvram/eeprom_at24c.c         | 37 ++++++++++++++++++++++++++++-----
> >  include/hw/nvram/eeprom_at24c.h | 16 ++++++++++++++
> >  2 files changed, 48 insertions(+), 5 deletions(-)
> > 
> > diff --git a/hw/nvram/eeprom_at24c.c b/hw/nvram/eeprom_at24c.c
> > index 98857e3626b9..f8d751fa278d 100644
> > --- a/hw/nvram/eeprom_at24c.c
> > +++ b/hw/nvram/eeprom_at24c.c
> > @@ -50,6 +50,9 @@ struct EEPROMState {
> >      uint8_t *mem;
> >  
> >      BlockBackend *blk;
> > +
> > +    const uint8_t *init_rom;
> > +    uint32_t init_rom_size;
> >  };
> >  
> >  static
> > @@ -131,19 +134,38 @@ int at24c_eeprom_send(I2CSlave *s, uint8_t data)
> >  
> >  I2CSlave *at24c_eeprom_init(I2CBus *bus, uint8_t address, uint32_t rom_size)
> >  {
> > -    I2CSlave *i2c_dev = i2c_slave_new(TYPE_AT24C_EE, address);
> > -    DeviceState *dev = DEVICE(i2c_dev);
> > +    return at24c_eeprom_init_rom(bus, address, rom_size, NULL, 0);
> > +}
> > +
> > +I2CSlave *at24c_eeprom_init_rom(I2CBus *bus, uint8_t address, uint32_t rom_size,
> > +                                const uint8_t *init_rom, uint32_t init_rom_size)
> > +{
> > +    EEPROMState *s;
> > +
> > +    s = AT24C_EE(qdev_new(TYPE_AT24C_EE));
> > +
> > +    qdev_prop_set_uint8(DEVICE(s), "address", address);
> 
> Why did you switch from using i2c_slave_new()?  Using it is more
> documentation and future-proofing than convenience.

Oh, yeah that's my bad. I was probably doing it so that all the qdev_prop_set
calls to the object are in the same place, but I probably should have just kept
i2c_slave_new() and initialized only the at24c-eeprom properties here, instead
of initializing the I2CSlave ones too.

- Peter

> 
> Other than that, looks good to me.
> 
> Reviewed-by: Corey Minyard <cminyard@mvista.com>
> 
> > +    qdev_prop_set_uint32(DEVICE(s), "rom-size", rom_size);
> >  
> > -    qdev_prop_set_uint32(dev, "rom-size", rom_size);
> > -    i2c_slave_realize_and_unref(i2c_dev, bus, &error_abort);
> > +    /* TODO: Model init_rom with QOM properties. */
> > +    s->init_rom = init_rom;
> > +    s->init_rom_size = init_rom_size;
> >  
> > -    return i2c_dev;
> > +    i2c_slave_realize_and_unref(I2C_SLAVE(s), bus, &error_abort);
> > +
> > +    return I2C_SLAVE(s);
> >  }
> >  
> >  static void at24c_eeprom_realize(DeviceState *dev, Error **errp)
> >  {
> >      EEPROMState *ee = AT24C_EE(dev);
> >  
> > +    if (ee->init_rom_size > ee->rsize) {
> > +        error_setg(errp, "%s: init rom is larger than rom: %u > %u",
> > +                   TYPE_AT24C_EE, ee->init_rom_size, ee->rsize);
> > +        return;
> > +    }
> > +
> >      if (ee->blk) {
> >          int64_t len = blk_getlength(ee->blk);
> >  
> > @@ -163,6 +185,7 @@ static void at24c_eeprom_realize(DeviceState *dev, Error **errp)
> >      }
> >  
> >      ee->mem = g_malloc0(ee->rsize);
> > +
> >  }
> >  
> >  static
> > @@ -176,6 +199,10 @@ void at24c_eeprom_reset(DeviceState *state)
> >  
> >      memset(ee->mem, 0, ee->rsize);
> >  
> > +    if (ee->init_rom) {
> > +        memcpy(ee->mem, ee->init_rom, MIN(ee->init_rom_size, ee->rsize));
> > +    }
> > +
> >      if (ee->blk) {
> >          int ret = blk_pread(ee->blk, 0, ee->rsize, ee->mem, 0);
> >  
> > diff --git a/include/hw/nvram/eeprom_at24c.h b/include/hw/nvram/eeprom_at24c.h
> > index 196db309d451..acb9857b2add 100644
> > --- a/include/hw/nvram/eeprom_at24c.h
> > +++ b/include/hw/nvram/eeprom_at24c.h
> > @@ -20,4 +20,20 @@
> >   */
> >  I2CSlave *at24c_eeprom_init(I2CBus *bus, uint8_t address, uint32_t rom_size);
> >  
> > +
> > +/*
> > + * Create and realize an AT24C EEPROM device on the heap with initial data.
> > + * @bus: I2C bus to put it on
> > + * @address: I2C address of the EEPROM slave when put on a bus
> > + * @rom_size: size of the EEPROM
> > + * @init_rom: Array of bytes to initialize EEPROM memory with
> > + * @init_rom_size: Size of @init_rom, must be less than or equal to @rom_size
> > + *
> > + * Create the device state structure, initialize it, put it on the specified
> > + * @bus, and drop the reference to it (the device is realized). Copies the data
> > + * from @init_rom to the beginning of the EEPROM memory buffer.
> > + */
> > +I2CSlave *at24c_eeprom_init_rom(I2CBus *bus, uint8_t address, uint32_t rom_size,
> > +                                const uint8_t *init_rom, uint32_t init_rom_size);
> > +
> >  #endif
> > -- 
> > 2.39.0
> > 
> >
Cédric Le Goater Jan. 27, 2023, 7:42 a.m. UTC | #5 
>>>   I2CSlave *at24c_eeprom_init(I2CBus *bus, uint8_t address, uint32_t rom_size)
>>>   {
>>> -    I2CSlave *i2c_dev = i2c_slave_new(TYPE_AT24C_EE, address);
>>> -    DeviceState *dev = DEVICE(i2c_dev);
>>> +    return at24c_eeprom_init_rom(bus, address, rom_size, NULL, 0);
>>> +}
>>> +
>>> +I2CSlave *at24c_eeprom_init_rom(I2CBus *bus, uint8_t address, uint32_t rom_size,
>>> +                                const uint8_t *init_rom, uint32_t init_rom_size)
>>> +{
>>> +    EEPROMState *s;
>>> +
>>> +    s = AT24C_EE(qdev_new(TYPE_AT24C_EE));
>>> +
>>> +    qdev_prop_set_uint8(DEVICE(s), "address", address);
>>
>> Why did you switch from using i2c_slave_new()?  Using it is more
>> documentation and future-proofing than convenience.
> 
> Oh, yeah that's my bad. I was probably doing it so that all the qdev_prop_set
> calls to the object are in the same place, but I probably should have just kept
> i2c_slave_new() and initialized only the at24c-eeprom properties here, instead
> of initializing the I2CSlave ones too.

Will you send a v5 ?

Thanks,

C.
Peter Delevoryas Jan. 28, 2023, 5:03 a.m. UTC | #6 
On Fri, Jan 27, 2023 at 08:42:40AM +0100, Cédric Le Goater wrote:
> > > >   I2CSlave *at24c_eeprom_init(I2CBus *bus, uint8_t address, uint32_t rom_size)
> > > >   {
> > > > -    I2CSlave *i2c_dev = i2c_slave_new(TYPE_AT24C_EE, address);
> > > > -    DeviceState *dev = DEVICE(i2c_dev);
> > > > +    return at24c_eeprom_init_rom(bus, address, rom_size, NULL, 0);
> > > > +}
> > > > +
> > > > +I2CSlave *at24c_eeprom_init_rom(I2CBus *bus, uint8_t address, uint32_t rom_size,
> > > > +                                const uint8_t *init_rom, uint32_t init_rom_size)
> > > > +{
> > > > +    EEPROMState *s;
> > > > +
> > > > +    s = AT24C_EE(qdev_new(TYPE_AT24C_EE));
> > > > +
> > > > +    qdev_prop_set_uint8(DEVICE(s), "address", address);
> > > 
> > > Why did you switch from using i2c_slave_new()?  Using it is more
> > > documentation and future-proofing than convenience.
> > 
> > Oh, yeah that's my bad. I was probably doing it so that all the qdev_prop_set
> > calls to the object are in the same place, but I probably should have just kept
> > i2c_slave_new() and initialized only the at24c-eeprom properties here, instead
> > of initializing the I2CSlave ones too.
> 
> Will you send a v5 ?

Oh! Yeah sure: I thought I had already missed the boat because I thought you
sent a pull request, but I see that it hasn't been pulled yet.

- Peter

> 
> Thanks,
> 
> C.
diff mbox series

Patch

diff --git a/hw/nvram/eeprom_at24c.c b/hw/nvram/eeprom_at24c.c
index 98857e3626b9..f8d751fa278d 100644
--- a/hw/nvram/eeprom_at24c.c
+++ b/hw/nvram/eeprom_at24c.c
@@ -50,6 +50,9 @@  struct EEPROMState {
     uint8_t *mem;
 
     BlockBackend *blk;
+
+    const uint8_t *init_rom;
+    uint32_t init_rom_size;
 };
 
 static
@@ -131,19 +134,38 @@  int at24c_eeprom_send(I2CSlave *s, uint8_t data)
 
 I2CSlave *at24c_eeprom_init(I2CBus *bus, uint8_t address, uint32_t rom_size)
 {
-    I2CSlave *i2c_dev = i2c_slave_new(TYPE_AT24C_EE, address);
-    DeviceState *dev = DEVICE(i2c_dev);
+    return at24c_eeprom_init_rom(bus, address, rom_size, NULL, 0);
+}
+
+I2CSlave *at24c_eeprom_init_rom(I2CBus *bus, uint8_t address, uint32_t rom_size,
+                                const uint8_t *init_rom, uint32_t init_rom_size)
+{
+    EEPROMState *s;
+
+    s = AT24C_EE(qdev_new(TYPE_AT24C_EE));
+
+    qdev_prop_set_uint8(DEVICE(s), "address", address);
+    qdev_prop_set_uint32(DEVICE(s), "rom-size", rom_size);
 
-    qdev_prop_set_uint32(dev, "rom-size", rom_size);
-    i2c_slave_realize_and_unref(i2c_dev, bus, &error_abort);
+    /* TODO: Model init_rom with QOM properties. */
+    s->init_rom = init_rom;
+    s->init_rom_size = init_rom_size;
 
-    return i2c_dev;
+    i2c_slave_realize_and_unref(I2C_SLAVE(s), bus, &error_abort);
+
+    return I2C_SLAVE(s);
 }
 
 static void at24c_eeprom_realize(DeviceState *dev, Error **errp)
 {
     EEPROMState *ee = AT24C_EE(dev);
 
+    if (ee->init_rom_size > ee->rsize) {
+        error_setg(errp, "%s: init rom is larger than rom: %u > %u",
+                   TYPE_AT24C_EE, ee->init_rom_size, ee->rsize);
+        return;
+    }
+
     if (ee->blk) {
         int64_t len = blk_getlength(ee->blk);
 
@@ -163,6 +185,7 @@  static void at24c_eeprom_realize(DeviceState *dev, Error **errp)
     }
 
     ee->mem = g_malloc0(ee->rsize);
+
 }
 
 static
@@ -176,6 +199,10 @@  void at24c_eeprom_reset(DeviceState *state)
 
     memset(ee->mem, 0, ee->rsize);
 
+    if (ee->init_rom) {
+        memcpy(ee->mem, ee->init_rom, MIN(ee->init_rom_size, ee->rsize));
+    }
+
     if (ee->blk) {
         int ret = blk_pread(ee->blk, 0, ee->rsize, ee->mem, 0);
 
diff --git a/include/hw/nvram/eeprom_at24c.h b/include/hw/nvram/eeprom_at24c.h
index 196db309d451..acb9857b2add 100644
--- a/include/hw/nvram/eeprom_at24c.h
+++ b/include/hw/nvram/eeprom_at24c.h
@@ -20,4 +20,20 @@ 
  */
 I2CSlave *at24c_eeprom_init(I2CBus *bus, uint8_t address, uint32_t rom_size);
 
+
+/*
+ * Create and realize an AT24C EEPROM device on the heap with initial data.
+ * @bus: I2C bus to put it on
+ * @address: I2C address of the EEPROM slave when put on a bus
+ * @rom_size: size of the EEPROM
+ * @init_rom: Array of bytes to initialize EEPROM memory with
+ * @init_rom_size: Size of @init_rom, must be less than or equal to @rom_size
+ *
+ * Create the device state structure, initialize it, put it on the specified
+ * @bus, and drop the reference to it (the device is realized). Copies the data
+ * from @init_rom to the beginning of the EEPROM memory buffer.
+ */
+I2CSlave *at24c_eeprom_init_rom(I2CBus *bus, uint8_t address, uint32_t rom_size,
+                                const uint8_t *init_rom, uint32_t init_rom_size);
+
 #endif