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

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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: David 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: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
David Daney 2012-08-22 12:03:57 -07:00 committed by Greg Kroah-Hartman
parent 9af514232e
commit d6ae0d578d
2 changed files with 82 additions and 35 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

34
Documentation/devicetree/bindings/misc/at25.txt
View File

@ -1,21 +1,35 @@
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:
at25@0 {
compatible = "atmel,at25";
reg = <0>
spi-max-frequency = <5000000>;
Additional compatible properties are also allowed.
at25,byte-len = <0x8000>;
at25,addr-mode = <2>;
at25,page-size = <64>;
};
Example:
at25@0 {
compatible = "atmel,at25", "st,m95256";
reg = <0>
spi-max-frequency = <5000000>;
spi-cpha;
spi-cpol;
pagesize = <64>;
size = <32768>;
address-width = <16>;
};

83
drivers/misc/eeprom/at25.c
View File

@ -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");
err = at25_np_to_chip(&spi->dev, np, &chip);
if (err)
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");
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;
}