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: 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>

diff --git a/Documentation/devicetree/bindings/misc/at25.txt b/Documentation/devicetree/bindings/misc/at25.txt
index ab3c327929dd26c09f19272219a4c8c26b7d3dd3..1d3447165c374f673aa9a717f94f2387cfd852f1 100644 (file)
--- 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 25003d6ceb56f2bca0364c81c881b79dee870711..4ed93dd541164d2a1763688caab1b351d3a799c9 100644 (file)
--- 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;
                }