linux/drivers/of/of_mtd.c
Ezequiel Garcia 6d9434ebb7 of_mtd: Add helpers to get ECC strength and ECC step size
This commit adds simple helpers to obtain the devicetree properties
that specify the ECC strength and ECC step size to use on a given
NAND controller.

Acked-by: Boris BREZILLON <b.brezillon.dev@gmail.com>
Signed-off-by: Ezequiel Garcia <ezequiel.garcia@free-electrons.com>
Signed-off-by: Brian Norris <computersforpeace@gmail.com>
2014-03-10 22:42:28 -07:00

120 lines
2.8 KiB
C

/*
* Copyright 2012 Jean-Christophe PLAGNIOL-VILLARD <plagnioj@jcrosoft.com>
*
* OF helpers for mtd.
*
* This file is released under the GPLv2
*
*/
#include <linux/kernel.h>
#include <linux/of_mtd.h>
#include <linux/mtd/nand.h>
#include <linux/export.h>
/**
* It maps 'enum nand_ecc_modes_t' found in include/linux/mtd/nand.h
* into the device tree binding of 'nand-ecc', so that MTD
* device driver can get nand ecc from device tree.
*/
static const char *nand_ecc_modes[] = {
[NAND_ECC_NONE] = "none",
[NAND_ECC_SOFT] = "soft",
[NAND_ECC_HW] = "hw",
[NAND_ECC_HW_SYNDROME] = "hw_syndrome",
[NAND_ECC_HW_OOB_FIRST] = "hw_oob_first",
[NAND_ECC_SOFT_BCH] = "soft_bch",
};
/**
* of_get_nand_ecc_mode - Get nand ecc mode for given device_node
* @np: Pointer to the given device_node
*
* The function gets ecc mode string from property 'nand-ecc-mode',
* and return its index in nand_ecc_modes table, or errno in error case.
*/
int of_get_nand_ecc_mode(struct device_node *np)
{
const char *pm;
int err, i;
err = of_property_read_string(np, "nand-ecc-mode", &pm);
if (err < 0)
return err;
for (i = 0; i < ARRAY_SIZE(nand_ecc_modes); i++)
if (!strcasecmp(pm, nand_ecc_modes[i]))
return i;
return -ENODEV;
}
EXPORT_SYMBOL_GPL(of_get_nand_ecc_mode);
/**
* of_get_nand_ecc_step_size - Get ECC step size associated to
* the required ECC strength (see below).
* @np: Pointer to the given device_node
*
* return the ECC step size, or errno in error case.
*/
int of_get_nand_ecc_step_size(struct device_node *np)
{
int ret;
u32 val;
ret = of_property_read_u32(np, "nand-ecc-step-size", &val);
return ret ? ret : val;
}
EXPORT_SYMBOL_GPL(of_get_nand_ecc_step_size);
/**
* of_get_nand_ecc_strength - Get required ECC strength over the
* correspnding step size as defined by 'nand-ecc-size'
* @np: Pointer to the given device_node
*
* return the ECC strength, or errno in error case.
*/
int of_get_nand_ecc_strength(struct device_node *np)
{
int ret;
u32 val;
ret = of_property_read_u32(np, "nand-ecc-strength", &val);
return ret ? ret : val;
}
EXPORT_SYMBOL_GPL(of_get_nand_ecc_strength);
/**
* of_get_nand_bus_width - Get nand bus witdh for given device_node
* @np: Pointer to the given device_node
*
* return bus width option, or errno in error case.
*/
int of_get_nand_bus_width(struct device_node *np)
{
u32 val;
if (of_property_read_u32(np, "nand-bus-width", &val))
return 8;
switch(val) {
case 8:
case 16:
return val;
default:
return -EIO;
}
}
EXPORT_SYMBOL_GPL(of_get_nand_bus_width);
/**
* of_get_nand_on_flash_bbt - Get nand on flash bbt for given device_node
* @np: Pointer to the given device_node
*
* return true if present false other wise
*/
bool of_get_nand_on_flash_bbt(struct device_node *np)
{
return of_property_read_bool(np, "nand-on-flash-bbt");
}
EXPORT_SYMBOL_GPL(of_get_nand_on_flash_bbt);