Commit d6ae0d57 authored by David Daney's avatar David Daney Committed by Greg Kroah-Hartman
Browse files

misc/at25, dt: Improve at25 SPI eeprom device tree bindings. 

Commit 002176db (misc: at25: Parse dt settings) added device tree
bindings the differ significantly in style from the I2C EEPROM
bindings and don't seem well vetted.  Here I deprecate (but still
support) the "at25,*" properties, and add what I hope is a better
alternative.  These new bindings also happen to be deployed in the
field and were previously submitted for consideration here:

https://lists.ozlabs.org/pipermail/devicetree-discuss/2012-May/015556.html



The advantages of the new bindings are that they are similar to the
I2C EEPROMs and they don't conflate read-only and the address width
modes in a binary encoded blob.

Signed-off-by: default avatarDavid Daney <david.daney@cavium.com>
Cc: Alexandre Pereira da Silva <aletes.xgr@gmail.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Michael Hennerich <michael.hennerich@analog.com>
Cc: Axel Lin <axel.lin@gmail.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 9af51423

Documentation/devicetree/bindings/misc/at25.txt

+24 −10
Original line number Diff line number Diff line 
Atmel AT25 eeprom

EEPROMs (SPI) compatible with Atmel at25.



Required properties:

- compatible : "atmel,at25".

- reg : chip select number

- spi-max-frequency : max spi frequency to use

- pagesize : size of the eeprom page

- size : total eeprom size in bytes

- address-width : number of address bits (one of 8, 16, or 24)



Optional properties:

- spi-cpha : SPI shifted clock phase, as per spi-bus bindings.

- spi-cpol : SPI inverse clock polarity, as per spi-bus bindings.

- read-only : this parameter-less property disables writes to the eeprom



Obsolete legacy properties are can be used in place of "size", "pagesize",

"address-width", and "read-only":

- at25,byte-len : total eeprom size in bytes

- at25,addr-mode : addr-mode flags, as defined in include/linux/spi/eeprom.h

- at25,page-size : size of the eeprom page



Examples:

Additional compatible properties are also allowed.



Example:

	at25@0 {

	compatible = "atmel,at25";

		compatible = "atmel,at25", "st,m95256";

		reg = <0>

		spi-max-frequency = <5000000>;

		spi-cpha;

		spi-cpol;



	at25,byte-len = <0x8000>;

	at25,addr-mode = <2>;

	at25,page-size = <64>;

		pagesize = <64>;

		size = <32768>;

		address-width = <16>;

	};

drivers/misc/eeprom/at25.c

+58 −25
Original line number Diff line number Diff line
@@ -302,6 +302,61 @@ static ssize_t at25_mem_write(struct memory_accessor *mem, const char *buf, 


/*-------------------------------------------------------------------------*/



static int at25_np_to_chip(struct device *dev,

			   struct device_node *np,

			   struct spi_eeprom *chip)

{

	u32 val;



	memset(chip, 0, sizeof(*chip));

	strncpy(chip->name, np->name, sizeof(chip->name));



	if (of_property_read_u32(np, "size", &val) == 0 ||

	    of_property_read_u32(np, "at25,byte-len", &val) == 0) {

		chip->byte_len = val;

	} else {

		dev_err(dev, "Error: missing \"size\" property\n");

		return -ENODEV;

	}



	if (of_property_read_u32(np, "pagesize", &val) == 0 ||

	    of_property_read_u32(np, "at25,page-size", &val) == 0) {

		chip->page_size = (u16)val;

	} else {

		dev_err(dev, "Error: missing \"pagesize\" property\n");

		return -ENODEV;

	}



	if (of_property_read_u32(np, "at25,addr-mode", &val) == 0) {

		chip->flags = (u16)val;

	} else {

		if (of_property_read_u32(np, "address-width", &val)) {

			dev_err(dev,

				"Error: missing \"address-width\" property\n");

			return -ENODEV;

		}

		switch (val) {

		case 8:

			chip->flags |= EE_ADDR1;

			break;

		case 16:

			chip->flags |= EE_ADDR2;

			break;

		case 24:

			chip->flags |= EE_ADDR3;

			break;

		default:

			dev_err(dev,

				"Error: bad \"address-width\" property: %u\n",

				val);

			return -ENODEV;

		}

		if (of_find_property(np, "read-only", NULL))

			chip->flags |= EE_READONLY;

	}

	return 0;

}



static int at25_probe(struct spi_device *spi)

{

	struct at25_data	*at25 = NULL;
@@ -314,33 +369,11 @@ static int at25_probe(struct spi_device *spi) 
	/* Chip description */

	if (!spi->dev.platform_data) {

		if (np) {

			u32 val;



			memset(&chip, 0, sizeof(chip));

			strncpy(chip.name, np->name, 10);



			err = of_property_read_u32(np, "at25,byte-len", &val);

			if (err) {

				dev_dbg(&spi->dev, "invalid chip dt description\n");

				goto fail;

			}

			chip.byte_len = val;



			err = of_property_read_u32(np, "at25,addr-mode", &val);

			if (err) {

				dev_dbg(&spi->dev, "invalid chip dt description\n");

				goto fail;

			}

			chip.flags = (u16)val;



			err = of_property_read_u32(np, "at25,page-size", &val);

			if (err) {

				dev_dbg(&spi->dev, "invalid chip dt description\n");

			err = at25_np_to_chip(&spi->dev, np, &chip);

			if (err)

				goto fail;

			}

			chip.page_size = (u16)val;

		} else {

			dev_dbg(&spi->dev, "no chip description\n");

			dev_err(&spi->dev, "Error: no chip description\n");

			err = -ENODEV;

			goto fail;

		}

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