508 строки
12 KiB
C
508 строки
12 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* OTP support for SPI NOR flashes
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*
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* Copyright (C) 2021 Michael Walle <michael@walle.cc>
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*/
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#include <linux/log2.h>
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#include <linux/mtd/mtd.h>
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#include <linux/mtd/spi-nor.h>
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#include "core.h"
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#define spi_nor_otp_region_len(nor) ((nor)->params->otp.org->len)
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#define spi_nor_otp_n_regions(nor) ((nor)->params->otp.org->n_regions)
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/**
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* spi_nor_otp_read_secr() - read security register
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* @nor: pointer to 'struct spi_nor'
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* @addr: offset to read from
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* @len: number of bytes to read
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* @buf: pointer to dst buffer
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*
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* Read a security register by using the SPINOR_OP_RSECR commands.
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*
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* In Winbond/GigaDevice datasheets the term "security register" stands for
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* an one-time-programmable memory area, consisting of multiple bytes (usually
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* 256). Thus one "security register" maps to one OTP region.
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*
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* This method is used on GigaDevice and Winbond flashes.
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*
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* Please note, the read must not span multiple registers.
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*
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* Return: number of bytes read successfully, -errno otherwise
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*/
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int spi_nor_otp_read_secr(struct spi_nor *nor, loff_t addr, size_t len, u8 *buf)
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{
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u8 addr_width, read_opcode, read_dummy;
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struct spi_mem_dirmap_desc *rdesc;
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enum spi_nor_protocol read_proto;
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int ret;
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read_opcode = nor->read_opcode;
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addr_width = nor->addr_width;
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read_dummy = nor->read_dummy;
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read_proto = nor->read_proto;
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rdesc = nor->dirmap.rdesc;
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nor->read_opcode = SPINOR_OP_RSECR;
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nor->read_dummy = 8;
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nor->read_proto = SNOR_PROTO_1_1_1;
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nor->dirmap.rdesc = NULL;
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ret = spi_nor_read_data(nor, addr, len, buf);
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nor->read_opcode = read_opcode;
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nor->addr_width = addr_width;
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nor->read_dummy = read_dummy;
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nor->read_proto = read_proto;
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nor->dirmap.rdesc = rdesc;
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return ret;
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}
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/**
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* spi_nor_otp_write_secr() - write security register
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* @nor: pointer to 'struct spi_nor'
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* @addr: offset to write to
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* @len: number of bytes to write
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* @buf: pointer to src buffer
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*
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* Write a security register by using the SPINOR_OP_PSECR commands.
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*
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* For more information on the term "security register", see the documentation
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* of spi_nor_otp_read_secr().
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*
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* This method is used on GigaDevice and Winbond flashes.
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*
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* Please note, the write must not span multiple registers.
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*
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* Return: number of bytes written successfully, -errno otherwise
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*/
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int spi_nor_otp_write_secr(struct spi_nor *nor, loff_t addr, size_t len,
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const u8 *buf)
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{
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enum spi_nor_protocol write_proto;
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struct spi_mem_dirmap_desc *wdesc;
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u8 addr_width, program_opcode;
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int ret, written;
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program_opcode = nor->program_opcode;
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addr_width = nor->addr_width;
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write_proto = nor->write_proto;
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wdesc = nor->dirmap.wdesc;
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nor->program_opcode = SPINOR_OP_PSECR;
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nor->write_proto = SNOR_PROTO_1_1_1;
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nor->dirmap.wdesc = NULL;
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/*
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* We only support a write to one single page. For now all winbond
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* flashes only have one page per security register.
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*/
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ret = spi_nor_write_enable(nor);
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if (ret)
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goto out;
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written = spi_nor_write_data(nor, addr, len, buf);
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if (written < 0)
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goto out;
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ret = spi_nor_wait_till_ready(nor);
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out:
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nor->program_opcode = program_opcode;
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nor->addr_width = addr_width;
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nor->write_proto = write_proto;
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nor->dirmap.wdesc = wdesc;
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return ret ?: written;
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}
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/**
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* spi_nor_otp_erase_secr() - erase a security register
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* @nor: pointer to 'struct spi_nor'
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* @addr: offset of the security register to be erased
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*
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* Erase a security register by using the SPINOR_OP_ESECR command.
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*
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* For more information on the term "security register", see the documentation
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* of spi_nor_otp_read_secr().
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*
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* This method is used on GigaDevice and Winbond flashes.
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*
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* Return: 0 on success, -errno otherwise
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*/
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int spi_nor_otp_erase_secr(struct spi_nor *nor, loff_t addr)
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{
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u8 erase_opcode = nor->erase_opcode;
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int ret;
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ret = spi_nor_write_enable(nor);
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if (ret)
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return ret;
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nor->erase_opcode = SPINOR_OP_ESECR;
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ret = spi_nor_erase_sector(nor, addr);
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nor->erase_opcode = erase_opcode;
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if (ret)
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return ret;
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return spi_nor_wait_till_ready(nor);
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}
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static int spi_nor_otp_lock_bit_cr(unsigned int region)
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{
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static const int lock_bits[] = { SR2_LB1, SR2_LB2, SR2_LB3 };
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if (region >= ARRAY_SIZE(lock_bits))
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return -EINVAL;
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return lock_bits[region];
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}
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/**
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* spi_nor_otp_lock_sr2() - lock the OTP region
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* @nor: pointer to 'struct spi_nor'
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* @region: OTP region
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*
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* Lock the OTP region by writing the status register-2. This method is used on
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* GigaDevice and Winbond flashes.
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*
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* Return: 0 on success, -errno otherwise.
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*/
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int spi_nor_otp_lock_sr2(struct spi_nor *nor, unsigned int region)
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{
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u8 *cr = nor->bouncebuf;
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int ret, lock_bit;
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lock_bit = spi_nor_otp_lock_bit_cr(region);
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if (lock_bit < 0)
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return lock_bit;
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ret = spi_nor_read_cr(nor, cr);
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if (ret)
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return ret;
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/* no need to write the register if region is already locked */
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if (cr[0] & lock_bit)
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return 0;
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cr[0] |= lock_bit;
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return spi_nor_write_16bit_cr_and_check(nor, cr[0]);
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}
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/**
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* spi_nor_otp_is_locked_sr2() - get the OTP region lock status
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* @nor: pointer to 'struct spi_nor'
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* @region: OTP region
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*
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* Retrieve the OTP region lock bit by reading the status register-2. This
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* method is used on GigaDevice and Winbond flashes.
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*
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* Return: 0 on success, -errno otherwise.
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*/
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int spi_nor_otp_is_locked_sr2(struct spi_nor *nor, unsigned int region)
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{
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u8 *cr = nor->bouncebuf;
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int ret, lock_bit;
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lock_bit = spi_nor_otp_lock_bit_cr(region);
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if (lock_bit < 0)
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return lock_bit;
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ret = spi_nor_read_cr(nor, cr);
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if (ret)
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return ret;
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return cr[0] & lock_bit;
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}
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static loff_t spi_nor_otp_region_start(const struct spi_nor *nor, unsigned int region)
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{
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const struct spi_nor_otp_organization *org = nor->params->otp.org;
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return org->base + region * org->offset;
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}
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static size_t spi_nor_otp_size(struct spi_nor *nor)
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{
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return spi_nor_otp_n_regions(nor) * spi_nor_otp_region_len(nor);
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}
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/* Translate the file offsets from and to OTP regions. */
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static loff_t spi_nor_otp_region_to_offset(struct spi_nor *nor, unsigned int region)
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{
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return region * spi_nor_otp_region_len(nor);
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}
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static unsigned int spi_nor_otp_offset_to_region(struct spi_nor *nor, loff_t ofs)
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{
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return div64_u64(ofs, spi_nor_otp_region_len(nor));
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}
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static int spi_nor_mtd_otp_info(struct mtd_info *mtd, size_t len,
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size_t *retlen, struct otp_info *buf)
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{
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struct spi_nor *nor = mtd_to_spi_nor(mtd);
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const struct spi_nor_otp_ops *ops = nor->params->otp.ops;
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unsigned int n_regions = spi_nor_otp_n_regions(nor);
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unsigned int i;
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int ret, locked;
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if (len < n_regions * sizeof(*buf))
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return -ENOSPC;
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ret = spi_nor_lock_and_prep(nor);
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if (ret)
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return ret;
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for (i = 0; i < n_regions; i++) {
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buf->start = spi_nor_otp_region_to_offset(nor, i);
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buf->length = spi_nor_otp_region_len(nor);
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locked = ops->is_locked(nor, i);
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if (locked < 0) {
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ret = locked;
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goto out;
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}
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buf->locked = !!locked;
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buf++;
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}
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*retlen = n_regions * sizeof(*buf);
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out:
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spi_nor_unlock_and_unprep(nor);
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return ret;
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}
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static int spi_nor_mtd_otp_range_is_locked(struct spi_nor *nor, loff_t ofs,
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size_t len)
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{
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const struct spi_nor_otp_ops *ops = nor->params->otp.ops;
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unsigned int region;
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int locked;
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/*
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* If any of the affected OTP regions are locked the entire range is
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* considered locked.
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*/
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for (region = spi_nor_otp_offset_to_region(nor, ofs);
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region <= spi_nor_otp_offset_to_region(nor, ofs + len - 1);
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region++) {
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locked = ops->is_locked(nor, region);
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/* take the branch it is locked or in case of an error */
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if (locked)
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return locked;
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}
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return 0;
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}
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static int spi_nor_mtd_otp_read_write(struct mtd_info *mtd, loff_t ofs,
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size_t total_len, size_t *retlen,
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const u8 *buf, bool is_write)
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{
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struct spi_nor *nor = mtd_to_spi_nor(mtd);
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const struct spi_nor_otp_ops *ops = nor->params->otp.ops;
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const size_t rlen = spi_nor_otp_region_len(nor);
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loff_t rstart, rofs;
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unsigned int region;
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size_t len;
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int ret;
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if (ofs < 0 || ofs >= spi_nor_otp_size(nor))
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return 0;
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/* don't access beyond the end */
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total_len = min_t(size_t, total_len, spi_nor_otp_size(nor) - ofs);
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if (!total_len)
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return 0;
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ret = spi_nor_lock_and_prep(nor);
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if (ret)
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return ret;
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if (is_write) {
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ret = spi_nor_mtd_otp_range_is_locked(nor, ofs, total_len);
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if (ret < 0) {
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goto out;
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} else if (ret) {
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ret = -EROFS;
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goto out;
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}
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}
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while (total_len) {
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/*
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* The OTP regions are mapped into a contiguous area starting
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* at 0 as expected by the MTD layer. This will map the MTD
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* file offsets to the address of an OTP region as used in the
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* actual SPI commands.
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*/
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region = spi_nor_otp_offset_to_region(nor, ofs);
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rstart = spi_nor_otp_region_start(nor, region);
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/*
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* The size of a OTP region is expected to be a power of two,
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* thus we can just mask the lower bits and get the offset into
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* a region.
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*/
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rofs = ofs & (rlen - 1);
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/* don't access beyond one OTP region */
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len = min_t(size_t, total_len, rlen - rofs);
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if (is_write)
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ret = ops->write(nor, rstart + rofs, len, buf);
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else
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ret = ops->read(nor, rstart + rofs, len, (u8 *)buf);
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if (ret == 0)
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ret = -EIO;
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if (ret < 0)
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goto out;
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*retlen += ret;
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ofs += ret;
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buf += ret;
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total_len -= ret;
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}
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ret = 0;
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out:
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spi_nor_unlock_and_unprep(nor);
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return ret;
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}
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static int spi_nor_mtd_otp_read(struct mtd_info *mtd, loff_t from, size_t len,
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size_t *retlen, u8 *buf)
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{
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return spi_nor_mtd_otp_read_write(mtd, from, len, retlen, buf, false);
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}
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static int spi_nor_mtd_otp_write(struct mtd_info *mtd, loff_t to, size_t len,
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size_t *retlen, const u8 *buf)
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{
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return spi_nor_mtd_otp_read_write(mtd, to, len, retlen, buf, true);
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}
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static int spi_nor_mtd_otp_erase(struct mtd_info *mtd, loff_t from, size_t len)
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{
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struct spi_nor *nor = mtd_to_spi_nor(mtd);
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const struct spi_nor_otp_ops *ops = nor->params->otp.ops;
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const size_t rlen = spi_nor_otp_region_len(nor);
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unsigned int region;
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loff_t rstart;
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int ret;
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/* OTP erase is optional */
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if (!ops->erase)
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return -EOPNOTSUPP;
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if (!len)
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return 0;
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if (from < 0 || (from + len) > spi_nor_otp_size(nor))
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return -EINVAL;
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/* the user has to explicitly ask for whole regions */
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if (!IS_ALIGNED(len, rlen) || !IS_ALIGNED(from, rlen))
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return -EINVAL;
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ret = spi_nor_lock_and_prep(nor);
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if (ret)
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return ret;
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ret = spi_nor_mtd_otp_range_is_locked(nor, from, len);
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if (ret < 0) {
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goto out;
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} else if (ret) {
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ret = -EROFS;
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goto out;
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}
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while (len) {
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region = spi_nor_otp_offset_to_region(nor, from);
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rstart = spi_nor_otp_region_start(nor, region);
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ret = ops->erase(nor, rstart);
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if (ret)
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goto out;
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len -= rlen;
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from += rlen;
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}
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out:
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spi_nor_unlock_and_unprep(nor);
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return ret;
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}
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static int spi_nor_mtd_otp_lock(struct mtd_info *mtd, loff_t from, size_t len)
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{
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struct spi_nor *nor = mtd_to_spi_nor(mtd);
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const struct spi_nor_otp_ops *ops = nor->params->otp.ops;
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const size_t rlen = spi_nor_otp_region_len(nor);
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unsigned int region;
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int ret;
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if (from < 0 || (from + len) > spi_nor_otp_size(nor))
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return -EINVAL;
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/* the user has to explicitly ask for whole regions */
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if (!IS_ALIGNED(len, rlen) || !IS_ALIGNED(from, rlen))
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return -EINVAL;
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ret = spi_nor_lock_and_prep(nor);
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if (ret)
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return ret;
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while (len) {
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region = spi_nor_otp_offset_to_region(nor, from);
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ret = ops->lock(nor, region);
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if (ret)
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goto out;
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len -= rlen;
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from += rlen;
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}
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out:
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spi_nor_unlock_and_unprep(nor);
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return ret;
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}
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void spi_nor_set_mtd_otp_ops(struct spi_nor *nor)
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{
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struct mtd_info *mtd = &nor->mtd;
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if (!nor->params->otp.ops)
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return;
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if (WARN_ON(!is_power_of_2(spi_nor_otp_region_len(nor))))
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return;
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/*
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* We only support user_prot callbacks (yet).
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*
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* Some SPI NOR flashes like Macronix ones can be ordered in two
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* different variants. One with a factory locked OTP area and one where
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* it is left to the user to write to it. The factory locked OTP is
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* usually preprogrammed with an "electrical serial number". We don't
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* support these for now.
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*/
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mtd->_get_user_prot_info = spi_nor_mtd_otp_info;
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mtd->_read_user_prot_reg = spi_nor_mtd_otp_read;
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mtd->_write_user_prot_reg = spi_nor_mtd_otp_write;
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mtd->_lock_user_prot_reg = spi_nor_mtd_otp_lock;
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mtd->_erase_user_prot_reg = spi_nor_mtd_otp_erase;
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}
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