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Date: Wed, 05 Sep 2012 17:57:33 -0500
From: Rob Herring <robherring2@...il.com>
To: David Daney <ddaney.cavm@...il.com>
CC: devicetree-discuss@...ts.ozlabs.org,
Grant Likely <grant.likely@...retlab.ca>,
Michael Hennerich <michael.hennerich@...log.com>,
David Daney <david.daney@...ium.com>,
Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
linux-kernel@...r.kernel.org, Axel Lin <axel.lin@...il.com>,
Alexandre Pereira da Silva <aletes.xgr@...il.com>
Subject: Re: [PATCH 1/2] misc/at25, dt: Improve at25 SPI eeprom device tree
bindings.
On 08/22/2012 02:03 PM, David Daney wrote:
> From: David Daney <david.daney@...ium.com>
>
> 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@...ium.com>
> Cc: Alexandre Pereira da Silva <aletes.xgr@...il.com>
> Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
> Cc: Michael Hennerich <michael.hennerich@...log.com>
> Cc: Axel Lin <axel.lin@...il.com>
Acked-by: Rob Herring <rob.herring@...xeda.com>
> ---
> Documentation/devicetree/bindings/misc/at25.txt | 34 +++++++---
> drivers/misc/eeprom/at25.c | 83 +++++++++++++++++--------
> 2 files changed, 82 insertions(+), 35 deletions(-)
>
> diff --git a/Documentation/devicetree/bindings/misc/at25.txt b/Documentation/devicetree/bindings/misc/at25.txt
> index ab3c327..1d34471 100644
> --- a/Documentation/devicetree/bindings/misc/at25.txt
> +++ b/Documentation/devicetree/bindings/misc/at25.txt
> @@ -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.
> +
> +Example:
> + at25@0 {
> + 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>;
> + };
> diff --git a/drivers/misc/eeprom/at25.c b/drivers/misc/eeprom/at25.c
> index 25003d6..4ed93dd 100644
> --- a/drivers/misc/eeprom/at25.c
> +++ b/drivers/misc/eeprom/at25.c
> @@ -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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