[v2] USB: serial: ftdi_sio: Add MTP NVM support

Message ID 1529599770-18133-1-git-send-email-loic.poulain@linaro.org
State Superseded
Headers show
Series
  • [v2] USB: serial: ftdi_sio: Add MTP NVM support
Related show

Commit Message

Loic Poulain June 21, 2018, 4:49 p.m.
Most of FTDI's devices have an EEPROM which records FTDI devices
configuration setting (e.g. the VID, PID, I/O config...) and user
data. FT230R chip integrates a 128-byte eeprom, FT230X a 2048-byte
eeprom...

This patch adds support for FTDI EEPROM read/write via USB control
transfers and register a new nvm device to the nvmem core.

This permits to expose the eeprom as a sysfs file, allowing userspace
to read/modify FTDI configuration and its user data without having to
rely on a specific userspace USB driver.

Moreover, any upcoming new tentative to add CBUS GPIO support could
integrate CBUS EEPROM configuration reading in order to determine
which of the CBUS pins are available as GPIO.

Signed-off-by: Loic Poulain <loic.poulain@linaro.org>

---
 v2: Use ifdef instead of IS_ENABLED
     error message in case of nvmem registering failure
     Fix space/tab in Kconfig

 drivers/usb/serial/Kconfig    |  13 ++++-
 drivers/usb/serial/ftdi_sio.c | 111 ++++++++++++++++++++++++++++++++++++++++++
 drivers/usb/serial/ftdi_sio.h |  28 +++++++++++
 3 files changed, 151 insertions(+), 1 deletion(-)

-- 
2.7.4

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Comments

Ajay Gupta June 21, 2018, 5:34 p.m. | #1
Hi Loic

On 6/21/18, Loic Poulain <loic.poulain@linaro.org> wrote:
> Most of FTDI's devices have an EEPROM which records FTDI devices

> configuration setting (e.g. the VID, PID, I/O config...) and user

> data. FT230R chip integrates a 128-byte eeprom, FT230X a 2048-byte

> eeprom...

>

> This patch adds support for FTDI EEPROM read/write via USB control

> transfers and register a new nvm device to the nvmem core.

>

> This permits to expose the eeprom as a sysfs file, allowing userspace

> to read/modify FTDI configuration and its user data without having to

> rely on a specific userspace USB driver.

>

> Moreover, any upcoming new tentative to add CBUS GPIO support could

> integrate CBUS EEPROM configuration reading in order to determine

> which of the CBUS pins are available as GPIO.

>

> Signed-off-by: Loic Poulain <loic.poulain@linaro.org>

> ---

>  v2: Use ifdef instead of IS_ENABLED

>      error message in case of nvmem registering failure

>      Fix space/tab in Kconfig

>

>  drivers/usb/serial/Kconfig    |  13 ++++-

>  drivers/usb/serial/ftdi_sio.c | 111

> ++++++++++++++++++++++++++++++++++++++++++

>  drivers/usb/serial/ftdi_sio.h |  28 +++++++++++

>  3 files changed, 151 insertions(+), 1 deletion(-)

>

> diff --git a/drivers/usb/serial/Kconfig b/drivers/usb/serial/Kconfig

> index 533f127..f05af5f 100644

> --- a/drivers/usb/serial/Kconfig

> +++ b/drivers/usb/serial/Kconfig

> @@ -153,7 +153,7 @@ config USB_SERIAL_CYPRESS_M8

>

>  	  Supported microcontrollers in the CY4601 family are:

>  		CY7C63741 CY7C63742 CY7C63743 CY7C64013

> -	

> +

There is no change here so please remove it.

>  	  To compile this driver as a module, choose M here: the

>  	  module will be called cypress_m8.

>

> @@ -181,6 +181,17 @@ config USB_SERIAL_FTDI_SIO

>  	  To compile this driver as a module, choose M here: the

>  	  module will be called ftdi_sio.

>

> +config USB_SERIAL_FTDI_SIO_NVMEM

> +	bool "FTDI MTP non-volatile memory support"

> +	depends on USB_SERIAL_FTDI_SIO

> +	select NVMEM

> +	default y

> +	help

> +	  Say yes here to add support for the MTP non-volatile memory

> +	  present on FTDI. Most of FTDI's devices have an EEPROM which

> +	  records FTDI device's configuration setting as well as user

> +	  data.

> +

>  config USB_SERIAL_VISOR

>  	tristate "USB Handspring Visor / Palm m50x / Sony Clie Driver"

>  	help

> diff --git a/drivers/usb/serial/ftdi_sio.c b/drivers/usb/serial/ftdi_sio.c

> index 7ea221d..9e242e8 100644

> --- a/drivers/usb/serial/ftdi_sio.c

> +++ b/drivers/usb/serial/ftdi_sio.c

> @@ -40,6 +40,7 @@

>  #include <linux/usb.h>

>  #include <linux/serial.h>

>  #include <linux/usb/serial.h>

> +#include <linux/nvmem-provider.h>

>  #include "ftdi_sio.h"

>  #include "ftdi_sio_ids.h"

>

> @@ -73,6 +74,8 @@ struct ftdi_private {

>  	unsigned int latency;		/* latency setting in use */

>  	unsigned short max_packet_size;

>  	struct mutex cfg_lock; /* Avoid mess by parallel calls of config ioctl()

> and change_speed() */

> +

> +	struct nvmem_device *eeprom;

>  };

>

>  /* struct ftdi_sio_quirk is used by devices requiring special attention.

> */

> @@ -1529,6 +1532,104 @@ static int get_lsr_info(struct usb_serial_port

> *port,

>  	return 0;

>  }

>

> +#ifdef CONFIG_USB_SERIAL_FTDI_SIO_NVMEM

> +

> +static int write_eeprom(void *priv, unsigned int off, void *_val, size_t

> bytes)

> +{

> +	struct usb_serial_port *port = priv;

> +	struct usb_serial *serial = port->serial;

> +	struct usb_device *udev = serial->dev;

> +	unsigned char *buf = _val;

> +

> +	while (bytes) { /* bytes value is always a multiple of 2 */


We should add check that 'bytes' is always multiple of 2 otherwise in
case its not then there will be memory overrun due to buf[1] access
below.
while (bytes / 2) {
}

> +		uint16_t val;

> +		int rv;

> +

> +		val = buf[0] + (buf[1] << 8);

> +

> +		rv = usb_control_msg(udev, usb_sndctrlpipe(udev, 0),

> +				     FTDI_SIO_WRITE_EEPROM_REQUEST,

> +				     FTDI_SIO_WRITE_EEPROM_REQUEST_TYPE,

> +				     val, off / 2, NULL, 0, WDR_TIMEOUT);

> +		if (rv < 0)

> +			return rv;

> +

> +		off += 2;

> +		buf += 2;

> +		bytes -= 2;

> +	}

> +

> +	return 0;

> +}

> +

> +static int read_eeprom(void *priv, unsigned int off, void *val, size_t

> bytes)

> +{

> +	struct usb_serial_port *port = priv;

> +	struct usb_serial *serial = port->serial;

> +	struct usb_device *udev = serial->dev;

> +	unsigned char *buf = val;

> +

> +	while (bytes) { /* bytes value is always a multiple of 2 */

same here

> +		int rv;

> +

> +		rv = usb_control_msg(udev, usb_rcvctrlpipe(udev, 0),

> +				     FTDI_SIO_READ_EEPROM_REQUEST,

> +				     FTDI_SIO_READ_EEPROM_REQUEST_TYPE,

> +				     0, off / 2, buf, 2, WDR_TIMEOUT);

> +		if (rv < 0)

> +			return rv;

> +

> +		off += 2;

> +		buf += 2;

> +		bytes -= 2;

> +	}

> +

> +	return 0;

> +}

> +

> +static int register_eeprom(struct usb_serial_port *port)

> +{

> +	struct ftdi_private *priv = usb_get_serial_port_data(port);

> +	struct nvmem_config nvmconf = {};

> +

> +	switch (priv->chip_type) {

> +	case FTX:

> +		nvmconf.size = 2048;

Better to have macro for 2048 and 128 instead of hardcoded value.

Thanks
Ajay
> +		break;

> +	case FT232RL:

> +		nvmconf.size = 128;

> +		break;

> +	default:

> +		return 0;

> +	}

> +

> +	nvmconf.word_size = 2;

> +	nvmconf.stride = 2;

> +	nvmconf.read_only = false;

> +	nvmconf.priv = port;

> +	nvmconf.dev = &port->dev;

> +	nvmconf.reg_read = read_eeprom;

> +	nvmconf.reg_write = write_eeprom;

> +	nvmconf.owner = THIS_MODULE;

> +

> +	priv->eeprom = nvmem_register(&nvmconf);

> +	if (IS_ERR(priv->eeprom)) {

> +		priv->eeprom = NULL;

> +		return -ENOMEM;

> +	}

> +

> +	return 0;

> +}

> +

> +static void unregister_eeprom(struct usb_serial_port *port)

> +{

> +	struct ftdi_private *priv = usb_get_serial_port_data(port);

> +

> +	if (priv->eeprom)

> +		nvmem_unregister(priv->eeprom);

> +}

> +

> +#endif /* CONFIG_USB_SERIAL_FTDI_SIO_NVMEM */

>

>  /* Determine type of FTDI chip based on USB config and descriptor. */

>  static void ftdi_determine_type(struct usb_serial_port *port)

> @@ -1814,6 +1915,13 @@ static int ftdi_sio_port_probe(struct usb_serial_port

> *port)

>  		priv->latency = 16;

>  	write_latency_timer(port);

>  	create_sysfs_attrs(port);

> +#ifdef CONFIG_USB_SERIAL_FTDI_SIO_NVMEM

> +	if (register_eeprom(port)) {

> +		dev_err(&port->dev, "Unable to register FTDI EEPROM\n");

> +		/* non-fatal */

> +	}

> +#endif

> +

>  	return 0;

>  }

>

> @@ -1931,6 +2039,9 @@ static int ftdi_sio_port_remove(struct usb_serial_port

> *port)

>  {

>  	struct ftdi_private *priv = usb_get_serial_port_data(port);

>

> +#ifdef CONFIG_USB_SERIAL_FTDI_SIO_NVMEM

> +	unregister_eeprom(port);

> +#endif

>  	remove_sysfs_attrs(port);

>

>  	kfree(priv);

> diff --git a/drivers/usb/serial/ftdi_sio.h b/drivers/usb/serial/ftdi_sio.h

> index dcd0b6e..9eab961 100644

> --- a/drivers/usb/serial/ftdi_sio.h

> +++ b/drivers/usb/serial/ftdi_sio.h

> @@ -36,6 +36,8 @@

>  #define FTDI_SIO_SET_ERROR_CHAR		7 /* Set the error character */

>  #define FTDI_SIO_SET_LATENCY_TIMER	9 /* Set the latency timer */

>  #define FTDI_SIO_GET_LATENCY_TIMER	10 /* Get the latency timer */

> +#define FTDI_SIO_READ_EEPROM		0x90 /* Read eeprom */

> +#define FTDI_SIO_WRITE_EEPROM		0x91 /* Write eeprom */

>

>  /* Interface indices for FT2232, FT2232H and FT4232H devices */

>  #define INTERFACE_A		1

> @@ -400,6 +402,32 @@ enum ftdi_sio_baudrate {

>   *

>   */

>

> + /* FTDI_SIO_READ_EEPROM */

> +#define FTDI_SIO_READ_EEPROM_REQUEST_TYPE 0xc0

> +#define FTDI_SIO_READ_EEPROM_REQUEST FTDI_SIO_READ_EEPROM

> +/*

> + *  BmRequestType:   1100 0000b

> + *  bRequest:        FTDI_SIO_READ_EEPROM

> + *  wValue:          0

> + *  wIndex:          Word Index

> + *  wLength:         2

> + *  Data:            return data (a word)

> + *

> + */

> +

> +/* FTDI_SIO_WRITE_EEPROM */

> +#define FTDI_SIO_WRITE_EEPROM_REQUEST_TYPE 0x40

> +#define FTDI_SIO_WRITE_EEPROM_REQUEST FTDI_SIO_WRITE_EEPROM

> +/*

> + *  BmRequestType:   0100 0000b

> + *  bRequest:        FTDI_SIO_WRITE_EEPROM

> + *  wValue:          Data (word)

> + *  wIndex:          Word Index

> + *  wLength:         0

> + *  Data:            None

> + *

> + */

> +

>  /* FTDI_SIO_GET_MODEM_STATUS */

>  /* Retrieve the current value of the modem status register */

>

> --

> 2.7.4

>

> --

> To unsubscribe from this list: send the line "unsubscribe linux-usb" in

> the body of a message to majordomo@vger.kernel.org

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>

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Loic Poulain June 22, 2018, 7:49 a.m. | #2
Hi Ajay,

Thanks for the review.

On 21 June 2018 at 19:34, Ajay Gupta <ajaykuee@gmail.com> wrote:
> Hi Loic

>

> On 6/21/18, Loic Poulain <loic.poulain@linaro.org> wrote:

>> Most of FTDI's devices have an EEPROM which records FTDI devices

>> configuration setting (e.g. the VID, PID, I/O config...) and user

>> data. FT230R chip integrates a 128-byte eeprom, FT230X a 2048-byte

>> eeprom...

>>

>> This patch adds support for FTDI EEPROM read/write via USB control

>> transfers and register a new nvm device to the nvmem core.

>>

>> This permits to expose the eeprom as a sysfs file, allowing userspace

>> to read/modify FTDI configuration and its user data without having to

>> rely on a specific userspace USB driver.

>>

>> Moreover, any upcoming new tentative to add CBUS GPIO support could

>> integrate CBUS EEPROM configuration reading in order to determine

>> which of the CBUS pins are available as GPIO.

>>

>> Signed-off-by: Loic Poulain <loic.poulain@linaro.org>

>> ---

>>  v2: Use ifdef instead of IS_ENABLED

>>      error message in case of nvmem registering failure

>>      Fix space/tab in Kconfig

>>

>>  drivers/usb/serial/Kconfig    |  13 ++++-

>>  drivers/usb/serial/ftdi_sio.c | 111

>> ++++++++++++++++++++++++++++++++++++++++++

>>  drivers/usb/serial/ftdi_sio.h |  28 +++++++++++

>>  3 files changed, 151 insertions(+), 1 deletion(-)

>>

>> diff --git a/drivers/usb/serial/Kconfig b/drivers/usb/serial/Kconfig

>> index 533f127..f05af5f 100644

>> --- a/drivers/usb/serial/Kconfig

>> +++ b/drivers/usb/serial/Kconfig

>> @@ -153,7 +153,7 @@ config USB_SERIAL_CYPRESS_M8

>>

>>         Supported microcontrollers in the CY4601 family are:

>>               CY7C63741 CY7C63742 CY7C63743 CY7C64013

>> -

>> +

> There is no change here so please remove it.

>

>>         To compile this driver as a module, choose M here: the

>>         module will be called cypress_m8.

>>

>> @@ -181,6 +181,17 @@ config USB_SERIAL_FTDI_SIO

>>         To compile this driver as a module, choose M here: the

>>         module will be called ftdi_sio.

>>

>> +config USB_SERIAL_FTDI_SIO_NVMEM

>> +     bool "FTDI MTP non-volatile memory support"

>> +     depends on USB_SERIAL_FTDI_SIO

>> +     select NVMEM

>> +     default y

>> +     help

>> +       Say yes here to add support for the MTP non-volatile memory

>> +       present on FTDI. Most of FTDI's devices have an EEPROM which

>> +       records FTDI device's configuration setting as well as user

>> +       data.

>> +

>>  config USB_SERIAL_VISOR

>>       tristate "USB Handspring Visor / Palm m50x / Sony Clie Driver"

>>       help

>> diff --git a/drivers/usb/serial/ftdi_sio.c b/drivers/usb/serial/ftdi_sio.c

>> index 7ea221d..9e242e8 100644

>> --- a/drivers/usb/serial/ftdi_sio.c

>> +++ b/drivers/usb/serial/ftdi_sio.c

>> @@ -40,6 +40,7 @@

>>  #include <linux/usb.h>

>>  #include <linux/serial.h>

>>  #include <linux/usb/serial.h>

>> +#include <linux/nvmem-provider.h>

>>  #include "ftdi_sio.h"

>>  #include "ftdi_sio_ids.h"

>>

>> @@ -73,6 +74,8 @@ struct ftdi_private {

>>       unsigned int latency;           /* latency setting in use */

>>       unsigned short max_packet_size;

>>       struct mutex cfg_lock; /* Avoid mess by parallel calls of config ioctl()

>> and change_speed() */

>> +

>> +     struct nvmem_device *eeprom;

>>  };

>>

>>  /* struct ftdi_sio_quirk is used by devices requiring special attention.

>> */

>> @@ -1529,6 +1532,104 @@ static int get_lsr_info(struct usb_serial_port

>> *port,

>>       return 0;

>>  }

>>

>> +#ifdef CONFIG_USB_SERIAL_FTDI_SIO_NVMEM

>> +

>> +static int write_eeprom(void *priv, unsigned int off, void *_val, size_t

>> bytes)

>> +{

>> +     struct usb_serial_port *port = priv;

>> +     struct usb_serial *serial = port->serial;

>> +     struct usb_device *udev = serial->dev;

>> +     unsigned char *buf = _val;

>> +

>> +     while (bytes) { /* bytes value is always a multiple of 2 */

>

> We should add check that 'bytes' is always multiple of 2 otherwise in

> case its not then there will be memory overrun due to buf[1] access

> below.

> while (bytes / 2) {

> }

>


This is in theory something which is guaranteed by the nvmem core since
we specified a 2-byte word size on registering. But looking at the code,
word-size is only checked on userspace access, not with kernel API
(e.g. nvmem_device_write). So yes It could be worth to double check here.


>> +             uint16_t val;

>> +             int rv;

>> +

>> +             val = buf[0] + (buf[1] << 8);

>> +

>> +             rv = usb_control_msg(udev, usb_sndctrlpipe(udev, 0),

>> +                                  FTDI_SIO_WRITE_EEPROM_REQUEST,

>> +                                  FTDI_SIO_WRITE_EEPROM_REQUEST_TYPE,

>> +                                  val, off / 2, NULL, 0, WDR_TIMEOUT);

>> +             if (rv < 0)

>> +                     return rv;

>> +

>> +             off += 2;

>> +             buf += 2;

>> +             bytes -= 2;

>> +     }

>> +

>> +     return 0;

>> +}

>> +

>> +static int read_eeprom(void *priv, unsigned int off, void *val, size_t

>> bytes)

>> +{

>> +     struct usb_serial_port *port = priv;

>> +     struct usb_serial *serial = port->serial;

>> +     struct usb_device *udev = serial->dev;

>> +     unsigned char *buf = val;

>> +

>> +     while (bytes) { /* bytes value is always a multiple of 2 */

> same here


Ok.

>

>> +             int rv;

>> +

>> +             rv = usb_control_msg(udev, usb_rcvctrlpipe(udev, 0),

>> +                                  FTDI_SIO_READ_EEPROM_REQUEST,

>> +                                  FTDI_SIO_READ_EEPROM_REQUEST_TYPE,

>> +                                  0, off / 2, buf, 2, WDR_TIMEOUT);

>> +             if (rv < 0)

>> +                     return rv;

>> +

>> +             off += 2;

>> +             buf += 2;

>> +             bytes -= 2;

>> +     }

>> +

>> +     return 0;

>> +}

>> +

>> +static int register_eeprom(struct usb_serial_port *port)

>> +{

>> +     struct ftdi_private *priv = usb_get_serial_port_data(port);

>> +     struct nvmem_config nvmconf = {};

>> +

>> +     switch (priv->chip_type) {

>> +     case FTX:

>> +             nvmconf.size = 2048;

> Better to have macro for 2048 and 128 instead of hardcoded value.

>


Ok.

> Thanks

> Ajay

>> +             break;

>> +     case FT232RL:

>> +             nvmconf.size = 128;

>> +             break;

>> +     default:

>> +             return 0;

>> +     }

>> +

>> +     nvmconf.word_size = 2;

>> +     nvmconf.stride = 2;

>> +     nvmconf.read_only = false;

>> +     nvmconf.priv = port;

>> +     nvmconf.dev = &port->dev;

>> +     nvmconf.reg_read = read_eeprom;

>> +     nvmconf.reg_write = write_eeprom;

>> +     nvmconf.owner = THIS_MODULE;

>> +

>> +     priv->eeprom = nvmem_register(&nvmconf);

>> +     if (IS_ERR(priv->eeprom)) {

>> +             priv->eeprom = NULL;

>> +             return -ENOMEM;

>> +     }

>> +

>> +     return 0;

>> +}

>> +

>> +static void unregister_eeprom(struct usb_serial_port *port)

>> +{

>> +     struct ftdi_private *priv = usb_get_serial_port_data(port);

>> +

>> +     if (priv->eeprom)

>> +             nvmem_unregister(priv->eeprom);

>> +}

>> +

>> +#endif /* CONFIG_USB_SERIAL_FTDI_SIO_NVMEM */

>>

>>  /* Determine type of FTDI chip based on USB config and descriptor. */

>>  static void ftdi_determine_type(struct usb_serial_port *port)

>> @@ -1814,6 +1915,13 @@ static int ftdi_sio_port_probe(struct usb_serial_port

>> *port)

>>               priv->latency = 16;

>>       write_latency_timer(port);

>>       create_sysfs_attrs(port);

>> +#ifdef CONFIG_USB_SERIAL_FTDI_SIO_NVMEM

>> +     if (register_eeprom(port)) {

>> +             dev_err(&port->dev, "Unable to register FTDI EEPROM\n");

>> +             /* non-fatal */

>> +     }

>> +#endif

>> +

>>       return 0;

>>  }

>>

>> @@ -1931,6 +2039,9 @@ static int ftdi_sio_port_remove(struct usb_serial_port

>> *port)

>>  {

>>       struct ftdi_private *priv = usb_get_serial_port_data(port);

>>

>> +#ifdef CONFIG_USB_SERIAL_FTDI_SIO_NVMEM

>> +     unregister_eeprom(port);

>> +#endif

>>       remove_sysfs_attrs(port);

>>

>>       kfree(priv);

>> diff --git a/drivers/usb/serial/ftdi_sio.h b/drivers/usb/serial/ftdi_sio.h

>> index dcd0b6e..9eab961 100644

>> --- a/drivers/usb/serial/ftdi_sio.h

>> +++ b/drivers/usb/serial/ftdi_sio.h

>> @@ -36,6 +36,8 @@

>>  #define FTDI_SIO_SET_ERROR_CHAR              7 /* Set the error character */

>>  #define FTDI_SIO_SET_LATENCY_TIMER   9 /* Set the latency timer */

>>  #define FTDI_SIO_GET_LATENCY_TIMER   10 /* Get the latency timer */

>> +#define FTDI_SIO_READ_EEPROM         0x90 /* Read eeprom */

>> +#define FTDI_SIO_WRITE_EEPROM                0x91 /* Write eeprom */

>>

>>  /* Interface indices for FT2232, FT2232H and FT4232H devices */

>>  #define INTERFACE_A          1

>> @@ -400,6 +402,32 @@ enum ftdi_sio_baudrate {

>>   *

>>   */

>>

>> + /* FTDI_SIO_READ_EEPROM */

>> +#define FTDI_SIO_READ_EEPROM_REQUEST_TYPE 0xc0

>> +#define FTDI_SIO_READ_EEPROM_REQUEST FTDI_SIO_READ_EEPROM

>> +/*

>> + *  BmRequestType:   1100 0000b

>> + *  bRequest:        FTDI_SIO_READ_EEPROM

>> + *  wValue:          0

>> + *  wIndex:          Word Index

>> + *  wLength:         2

>> + *  Data:            return data (a word)

>> + *

>> + */

>> +

>> +/* FTDI_SIO_WRITE_EEPROM */

>> +#define FTDI_SIO_WRITE_EEPROM_REQUEST_TYPE 0x40

>> +#define FTDI_SIO_WRITE_EEPROM_REQUEST FTDI_SIO_WRITE_EEPROM

>> +/*

>> + *  BmRequestType:   0100 0000b

>> + *  bRequest:        FTDI_SIO_WRITE_EEPROM

>> + *  wValue:          Data (word)

>> + *  wIndex:          Word Index

>> + *  wLength:         0

>> + *  Data:            None

>> + *

>> + */

>> +

>>  /* FTDI_SIO_GET_MODEM_STATUS */

>>  /* Retrieve the current value of the modem status register */

>>

>> --

>> 2.7.4

>>

>> --

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Patch

diff --git a/drivers/usb/serial/Kconfig b/drivers/usb/serial/Kconfig
index 533f127..f05af5f 100644
--- a/drivers/usb/serial/Kconfig
+++ b/drivers/usb/serial/Kconfig
@@ -153,7 +153,7 @@  config USB_SERIAL_CYPRESS_M8
 
 	  Supported microcontrollers in the CY4601 family are:
 		CY7C63741 CY7C63742 CY7C63743 CY7C64013
-	
+
 	  To compile this driver as a module, choose M here: the
 	  module will be called cypress_m8.
 
@@ -181,6 +181,17 @@  config USB_SERIAL_FTDI_SIO
 	  To compile this driver as a module, choose M here: the
 	  module will be called ftdi_sio.
 
+config USB_SERIAL_FTDI_SIO_NVMEM
+	bool "FTDI MTP non-volatile memory support"
+	depends on USB_SERIAL_FTDI_SIO
+	select NVMEM
+	default y
+	help
+	  Say yes here to add support for the MTP non-volatile memory
+	  present on FTDI. Most of FTDI's devices have an EEPROM which
+	  records FTDI device's configuration setting as well as user
+	  data.
+
 config USB_SERIAL_VISOR
 	tristate "USB Handspring Visor / Palm m50x / Sony Clie Driver"
 	help
diff --git a/drivers/usb/serial/ftdi_sio.c b/drivers/usb/serial/ftdi_sio.c
index 7ea221d..9e242e8 100644
--- a/drivers/usb/serial/ftdi_sio.c
+++ b/drivers/usb/serial/ftdi_sio.c
@@ -40,6 +40,7 @@ 
 #include <linux/usb.h>
 #include <linux/serial.h>
 #include <linux/usb/serial.h>
+#include <linux/nvmem-provider.h>
 #include "ftdi_sio.h"
 #include "ftdi_sio_ids.h"
 
@@ -73,6 +74,8 @@  struct ftdi_private {
 	unsigned int latency;		/* latency setting in use */
 	unsigned short max_packet_size;
 	struct mutex cfg_lock; /* Avoid mess by parallel calls of config ioctl() and change_speed() */
+
+	struct nvmem_device *eeprom;
 };
 
 /* struct ftdi_sio_quirk is used by devices requiring special attention. */
@@ -1529,6 +1532,104 @@  static int get_lsr_info(struct usb_serial_port *port,
 	return 0;
 }
 
+#ifdef CONFIG_USB_SERIAL_FTDI_SIO_NVMEM
+
+static int write_eeprom(void *priv, unsigned int off, void *_val, size_t bytes)
+{
+	struct usb_serial_port *port = priv;
+	struct usb_serial *serial = port->serial;
+	struct usb_device *udev = serial->dev;
+	unsigned char *buf = _val;
+
+	while (bytes) { /* bytes value is always a multiple of 2 */
+		uint16_t val;
+		int rv;
+
+		val = buf[0] + (buf[1] << 8);
+
+		rv = usb_control_msg(udev, usb_sndctrlpipe(udev, 0),
+				     FTDI_SIO_WRITE_EEPROM_REQUEST,
+				     FTDI_SIO_WRITE_EEPROM_REQUEST_TYPE,
+				     val, off / 2, NULL, 0, WDR_TIMEOUT);
+		if (rv < 0)
+			return rv;
+
+		off += 2;
+		buf += 2;
+		bytes -= 2;
+	}
+
+	return 0;
+}
+
+static int read_eeprom(void *priv, unsigned int off, void *val, size_t bytes)
+{
+	struct usb_serial_port *port = priv;
+	struct usb_serial *serial = port->serial;
+	struct usb_device *udev = serial->dev;
+	unsigned char *buf = val;
+
+	while (bytes) { /* bytes value is always a multiple of 2 */
+		int rv;
+
+		rv = usb_control_msg(udev, usb_rcvctrlpipe(udev, 0),
+				     FTDI_SIO_READ_EEPROM_REQUEST,
+				     FTDI_SIO_READ_EEPROM_REQUEST_TYPE,
+				     0, off / 2, buf, 2, WDR_TIMEOUT);
+		if (rv < 0)
+			return rv;
+
+		off += 2;
+		buf += 2;
+		bytes -= 2;
+	}
+
+	return 0;
+}
+
+static int register_eeprom(struct usb_serial_port *port)
+{
+	struct ftdi_private *priv = usb_get_serial_port_data(port);
+	struct nvmem_config nvmconf = {};
+
+	switch (priv->chip_type) {
+	case FTX:
+		nvmconf.size = 2048;
+		break;
+	case FT232RL:
+		nvmconf.size = 128;
+		break;
+	default:
+		return 0;
+	}
+
+	nvmconf.word_size = 2;
+	nvmconf.stride = 2;
+	nvmconf.read_only = false;
+	nvmconf.priv = port;
+	nvmconf.dev = &port->dev;
+	nvmconf.reg_read = read_eeprom;
+	nvmconf.reg_write = write_eeprom;
+	nvmconf.owner = THIS_MODULE;
+
+	priv->eeprom = nvmem_register(&nvmconf);
+	if (IS_ERR(priv->eeprom)) {
+		priv->eeprom = NULL;
+		return -ENOMEM;
+	}
+
+	return 0;
+}
+
+static void unregister_eeprom(struct usb_serial_port *port)
+{
+	struct ftdi_private *priv = usb_get_serial_port_data(port);
+
+	if (priv->eeprom)
+		nvmem_unregister(priv->eeprom);
+}
+
+#endif /* CONFIG_USB_SERIAL_FTDI_SIO_NVMEM */
 
 /* Determine type of FTDI chip based on USB config and descriptor. */
 static void ftdi_determine_type(struct usb_serial_port *port)
@@ -1814,6 +1915,13 @@  static int ftdi_sio_port_probe(struct usb_serial_port *port)
 		priv->latency = 16;
 	write_latency_timer(port);
 	create_sysfs_attrs(port);
+#ifdef CONFIG_USB_SERIAL_FTDI_SIO_NVMEM
+	if (register_eeprom(port)) {
+		dev_err(&port->dev, "Unable to register FTDI EEPROM\n");
+		/* non-fatal */
+	}
+#endif
+
 	return 0;
 }
 
@@ -1931,6 +2039,9 @@  static int ftdi_sio_port_remove(struct usb_serial_port *port)
 {
 	struct ftdi_private *priv = usb_get_serial_port_data(port);
 
+#ifdef CONFIG_USB_SERIAL_FTDI_SIO_NVMEM
+	unregister_eeprom(port);
+#endif
 	remove_sysfs_attrs(port);
 
 	kfree(priv);
diff --git a/drivers/usb/serial/ftdi_sio.h b/drivers/usb/serial/ftdi_sio.h
index dcd0b6e..9eab961 100644
--- a/drivers/usb/serial/ftdi_sio.h
+++ b/drivers/usb/serial/ftdi_sio.h
@@ -36,6 +36,8 @@ 
 #define FTDI_SIO_SET_ERROR_CHAR		7 /* Set the error character */
 #define FTDI_SIO_SET_LATENCY_TIMER	9 /* Set the latency timer */
 #define FTDI_SIO_GET_LATENCY_TIMER	10 /* Get the latency timer */
+#define FTDI_SIO_READ_EEPROM		0x90 /* Read eeprom */
+#define FTDI_SIO_WRITE_EEPROM		0x91 /* Write eeprom */
 
 /* Interface indices for FT2232, FT2232H and FT4232H devices */
 #define INTERFACE_A		1
@@ -400,6 +402,32 @@  enum ftdi_sio_baudrate {
  *
  */
 
+ /* FTDI_SIO_READ_EEPROM */
+#define FTDI_SIO_READ_EEPROM_REQUEST_TYPE 0xc0
+#define FTDI_SIO_READ_EEPROM_REQUEST FTDI_SIO_READ_EEPROM
+/*
+ *  BmRequestType:   1100 0000b
+ *  bRequest:        FTDI_SIO_READ_EEPROM
+ *  wValue:          0
+ *  wIndex:          Word Index
+ *  wLength:         2
+ *  Data:            return data (a word)
+ *
+ */
+
+/* FTDI_SIO_WRITE_EEPROM */
+#define FTDI_SIO_WRITE_EEPROM_REQUEST_TYPE 0x40
+#define FTDI_SIO_WRITE_EEPROM_REQUEST FTDI_SIO_WRITE_EEPROM
+/*
+ *  BmRequestType:   0100 0000b
+ *  bRequest:        FTDI_SIO_WRITE_EEPROM
+ *  wValue:          Data (word)
+ *  wIndex:          Word Index
+ *  wLength:         0
+ *  Data:            None
+ *
+ */
+
 /* FTDI_SIO_GET_MODEM_STATUS */
 /* Retrieve the current value of the modem status register */