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-rw-r--r--drivers/mtd/spi-nor/otp.c507
1 files changed, 507 insertions, 0 deletions
diff --git a/drivers/mtd/spi-nor/otp.c b/drivers/mtd/spi-nor/otp.c
new file mode 100644
index 000000000..00ab0d2d6
--- /dev/null
+++ b/drivers/mtd/spi-nor/otp.c
@@ -0,0 +1,507 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * OTP support for SPI NOR flashes
+ *
+ * Copyright (C) 2021 Michael Walle <michael@walle.cc>
+ */
+
+#include <linux/log2.h>
+#include <linux/mtd/mtd.h>
+#include <linux/mtd/spi-nor.h>
+
+#include "core.h"
+
+#define spi_nor_otp_region_len(nor) ((nor)->params->otp.org->len)
+#define spi_nor_otp_n_regions(nor) ((nor)->params->otp.org->n_regions)
+
+/**
+ * spi_nor_otp_read_secr() - read security register
+ * @nor: pointer to 'struct spi_nor'
+ * @addr: offset to read from
+ * @len: number of bytes to read
+ * @buf: pointer to dst buffer
+ *
+ * Read a security register by using the SPINOR_OP_RSECR commands.
+ *
+ * In Winbond/GigaDevice datasheets the term "security register" stands for
+ * an one-time-programmable memory area, consisting of multiple bytes (usually
+ * 256). Thus one "security register" maps to one OTP region.
+ *
+ * This method is used on GigaDevice and Winbond flashes.
+ *
+ * Please note, the read must not span multiple registers.
+ *
+ * Return: number of bytes read successfully, -errno otherwise
+ */
+int spi_nor_otp_read_secr(struct spi_nor *nor, loff_t addr, size_t len, u8 *buf)
+{
+ u8 addr_nbytes, read_opcode, read_dummy;
+ struct spi_mem_dirmap_desc *rdesc;
+ enum spi_nor_protocol read_proto;
+ int ret;
+
+ read_opcode = nor->read_opcode;
+ addr_nbytes = nor->addr_nbytes;
+ read_dummy = nor->read_dummy;
+ read_proto = nor->read_proto;
+ rdesc = nor->dirmap.rdesc;
+
+ nor->read_opcode = SPINOR_OP_RSECR;
+ nor->read_dummy = 8;
+ nor->read_proto = SNOR_PROTO_1_1_1;
+ nor->dirmap.rdesc = NULL;
+
+ ret = spi_nor_read_data(nor, addr, len, buf);
+
+ nor->read_opcode = read_opcode;
+ nor->addr_nbytes = addr_nbytes;
+ nor->read_dummy = read_dummy;
+ nor->read_proto = read_proto;
+ nor->dirmap.rdesc = rdesc;
+
+ return ret;
+}
+
+/**
+ * spi_nor_otp_write_secr() - write security register
+ * @nor: pointer to 'struct spi_nor'
+ * @addr: offset to write to
+ * @len: number of bytes to write
+ * @buf: pointer to src buffer
+ *
+ * Write a security register by using the SPINOR_OP_PSECR commands.
+ *
+ * For more information on the term "security register", see the documentation
+ * of spi_nor_otp_read_secr().
+ *
+ * This method is used on GigaDevice and Winbond flashes.
+ *
+ * Please note, the write must not span multiple registers.
+ *
+ * Return: number of bytes written successfully, -errno otherwise
+ */
+int spi_nor_otp_write_secr(struct spi_nor *nor, loff_t addr, size_t len,
+ const u8 *buf)
+{
+ enum spi_nor_protocol write_proto;
+ struct spi_mem_dirmap_desc *wdesc;
+ u8 addr_nbytes, program_opcode;
+ int ret, written;
+
+ program_opcode = nor->program_opcode;
+ addr_nbytes = nor->addr_nbytes;
+ write_proto = nor->write_proto;
+ wdesc = nor->dirmap.wdesc;
+
+ nor->program_opcode = SPINOR_OP_PSECR;
+ nor->write_proto = SNOR_PROTO_1_1_1;
+ nor->dirmap.wdesc = NULL;
+
+ /*
+ * We only support a write to one single page. For now all winbond
+ * flashes only have one page per security register.
+ */
+ ret = spi_nor_write_enable(nor);
+ if (ret)
+ goto out;
+
+ written = spi_nor_write_data(nor, addr, len, buf);
+ if (written < 0)
+ goto out;
+
+ ret = spi_nor_wait_till_ready(nor);
+
+out:
+ nor->program_opcode = program_opcode;
+ nor->addr_nbytes = addr_nbytes;
+ nor->write_proto = write_proto;
+ nor->dirmap.wdesc = wdesc;
+
+ return ret ?: written;
+}
+
+/**
+ * spi_nor_otp_erase_secr() - erase a security register
+ * @nor: pointer to 'struct spi_nor'
+ * @addr: offset of the security register to be erased
+ *
+ * Erase a security register by using the SPINOR_OP_ESECR command.
+ *
+ * For more information on the term "security register", see the documentation
+ * of spi_nor_otp_read_secr().
+ *
+ * This method is used on GigaDevice and Winbond flashes.
+ *
+ * Return: 0 on success, -errno otherwise
+ */
+int spi_nor_otp_erase_secr(struct spi_nor *nor, loff_t addr)
+{
+ u8 erase_opcode = nor->erase_opcode;
+ int ret;
+
+ ret = spi_nor_write_enable(nor);
+ if (ret)
+ return ret;
+
+ nor->erase_opcode = SPINOR_OP_ESECR;
+ ret = spi_nor_erase_sector(nor, addr);
+ nor->erase_opcode = erase_opcode;
+ if (ret)
+ return ret;
+
+ return spi_nor_wait_till_ready(nor);
+}
+
+static int spi_nor_otp_lock_bit_cr(unsigned int region)
+{
+ static const int lock_bits[] = { SR2_LB1, SR2_LB2, SR2_LB3 };
+
+ if (region >= ARRAY_SIZE(lock_bits))
+ return -EINVAL;
+
+ return lock_bits[region];
+}
+
+/**
+ * spi_nor_otp_lock_sr2() - lock the OTP region
+ * @nor: pointer to 'struct spi_nor'
+ * @region: OTP region
+ *
+ * Lock the OTP region by writing the status register-2. This method is used on
+ * GigaDevice and Winbond flashes.
+ *
+ * Return: 0 on success, -errno otherwise.
+ */
+int spi_nor_otp_lock_sr2(struct spi_nor *nor, unsigned int region)
+{
+ u8 *cr = nor->bouncebuf;
+ int ret, lock_bit;
+
+ lock_bit = spi_nor_otp_lock_bit_cr(region);
+ if (lock_bit < 0)
+ return lock_bit;
+
+ ret = spi_nor_read_cr(nor, cr);
+ if (ret)
+ return ret;
+
+ /* no need to write the register if region is already locked */
+ if (cr[0] & lock_bit)
+ return 0;
+
+ cr[0] |= lock_bit;
+
+ return spi_nor_write_16bit_cr_and_check(nor, cr[0]);
+}
+
+/**
+ * spi_nor_otp_is_locked_sr2() - get the OTP region lock status
+ * @nor: pointer to 'struct spi_nor'
+ * @region: OTP region
+ *
+ * Retrieve the OTP region lock bit by reading the status register-2. This
+ * method is used on GigaDevice and Winbond flashes.
+ *
+ * Return: 0 on success, -errno otherwise.
+ */
+int spi_nor_otp_is_locked_sr2(struct spi_nor *nor, unsigned int region)
+{
+ u8 *cr = nor->bouncebuf;
+ int ret, lock_bit;
+
+ lock_bit = spi_nor_otp_lock_bit_cr(region);
+ if (lock_bit < 0)
+ return lock_bit;
+
+ ret = spi_nor_read_cr(nor, cr);
+ if (ret)
+ return ret;
+
+ return cr[0] & lock_bit;
+}
+
+static loff_t spi_nor_otp_region_start(const struct spi_nor *nor, unsigned int region)
+{
+ const struct spi_nor_otp_organization *org = nor->params->otp.org;
+
+ return org->base + region * org->offset;
+}
+
+static size_t spi_nor_otp_size(struct spi_nor *nor)
+{
+ return spi_nor_otp_n_regions(nor) * spi_nor_otp_region_len(nor);
+}
+
+/* Translate the file offsets from and to OTP regions. */
+static loff_t spi_nor_otp_region_to_offset(struct spi_nor *nor, unsigned int region)
+{
+ return region * spi_nor_otp_region_len(nor);
+}
+
+static unsigned int spi_nor_otp_offset_to_region(struct spi_nor *nor, loff_t ofs)
+{
+ return div64_u64(ofs, spi_nor_otp_region_len(nor));
+}
+
+static int spi_nor_mtd_otp_info(struct mtd_info *mtd, size_t len,
+ size_t *retlen, struct otp_info *buf)
+{
+ struct spi_nor *nor = mtd_to_spi_nor(mtd);
+ const struct spi_nor_otp_ops *ops = nor->params->otp.ops;
+ unsigned int n_regions = spi_nor_otp_n_regions(nor);
+ unsigned int i;
+ int ret, locked;
+
+ if (len < n_regions * sizeof(*buf))
+ return -ENOSPC;
+
+ ret = spi_nor_lock_and_prep(nor);
+ if (ret)
+ return ret;
+
+ for (i = 0; i < n_regions; i++) {
+ buf->start = spi_nor_otp_region_to_offset(nor, i);
+ buf->length = spi_nor_otp_region_len(nor);
+
+ locked = ops->is_locked(nor, i);
+ if (locked < 0) {
+ ret = locked;
+ goto out;
+ }
+
+ buf->locked = !!locked;
+ buf++;
+ }
+
+ *retlen = n_regions * sizeof(*buf);
+
+out:
+ spi_nor_unlock_and_unprep(nor);
+
+ return ret;
+}
+
+static int spi_nor_mtd_otp_range_is_locked(struct spi_nor *nor, loff_t ofs,
+ size_t len)
+{
+ const struct spi_nor_otp_ops *ops = nor->params->otp.ops;
+ unsigned int region;
+ int locked;
+
+ /*
+ * If any of the affected OTP regions are locked the entire range is
+ * considered locked.
+ */
+ for (region = spi_nor_otp_offset_to_region(nor, ofs);
+ region <= spi_nor_otp_offset_to_region(nor, ofs + len - 1);
+ region++) {
+ locked = ops->is_locked(nor, region);
+ /* take the branch it is locked or in case of an error */
+ if (locked)
+ return locked;
+ }
+
+ return 0;
+}
+
+static int spi_nor_mtd_otp_read_write(struct mtd_info *mtd, loff_t ofs,
+ size_t total_len, size_t *retlen,
+ const u8 *buf, bool is_write)
+{
+ struct spi_nor *nor = mtd_to_spi_nor(mtd);
+ const struct spi_nor_otp_ops *ops = nor->params->otp.ops;
+ const size_t rlen = spi_nor_otp_region_len(nor);
+ loff_t rstart, rofs;
+ unsigned int region;
+ size_t len;
+ int ret;
+
+ if (ofs < 0 || ofs >= spi_nor_otp_size(nor))
+ return 0;
+
+ /* don't access beyond the end */
+ total_len = min_t(size_t, total_len, spi_nor_otp_size(nor) - ofs);
+
+ if (!total_len)
+ return 0;
+
+ ret = spi_nor_lock_and_prep(nor);
+ if (ret)
+ return ret;
+
+ if (is_write) {
+ ret = spi_nor_mtd_otp_range_is_locked(nor, ofs, total_len);
+ if (ret < 0) {
+ goto out;
+ } else if (ret) {
+ ret = -EROFS;
+ goto out;
+ }
+ }
+
+ while (total_len) {
+ /*
+ * The OTP regions are mapped into a contiguous area starting
+ * at 0 as expected by the MTD layer. This will map the MTD
+ * file offsets to the address of an OTP region as used in the
+ * actual SPI commands.
+ */
+ region = spi_nor_otp_offset_to_region(nor, ofs);
+ rstart = spi_nor_otp_region_start(nor, region);
+
+ /*
+ * The size of a OTP region is expected to be a power of two,
+ * thus we can just mask the lower bits and get the offset into
+ * a region.
+ */
+ rofs = ofs & (rlen - 1);
+
+ /* don't access beyond one OTP region */
+ len = min_t(size_t, total_len, rlen - rofs);
+
+ if (is_write)
+ ret = ops->write(nor, rstart + rofs, len, buf);
+ else
+ ret = ops->read(nor, rstart + rofs, len, (u8 *)buf);
+ if (ret == 0)
+ ret = -EIO;
+ if (ret < 0)
+ goto out;
+
+ *retlen += ret;
+ ofs += ret;
+ buf += ret;
+ total_len -= ret;
+ }
+ ret = 0;
+
+out:
+ spi_nor_unlock_and_unprep(nor);
+ return ret;
+}
+
+static int spi_nor_mtd_otp_read(struct mtd_info *mtd, loff_t from, size_t len,
+ size_t *retlen, u8 *buf)
+{
+ return spi_nor_mtd_otp_read_write(mtd, from, len, retlen, buf, false);
+}
+
+static int spi_nor_mtd_otp_write(struct mtd_info *mtd, loff_t to, size_t len,
+ size_t *retlen, const u8 *buf)
+{
+ return spi_nor_mtd_otp_read_write(mtd, to, len, retlen, buf, true);
+}
+
+static int spi_nor_mtd_otp_erase(struct mtd_info *mtd, loff_t from, size_t len)
+{
+ struct spi_nor *nor = mtd_to_spi_nor(mtd);
+ const struct spi_nor_otp_ops *ops = nor->params->otp.ops;
+ const size_t rlen = spi_nor_otp_region_len(nor);
+ unsigned int region;
+ loff_t rstart;
+ int ret;
+
+ /* OTP erase is optional */
+ if (!ops->erase)
+ return -EOPNOTSUPP;
+
+ if (!len)
+ return 0;
+
+ if (from < 0 || (from + len) > spi_nor_otp_size(nor))
+ return -EINVAL;
+
+ /* the user has to explicitly ask for whole regions */
+ if (!IS_ALIGNED(len, rlen) || !IS_ALIGNED(from, rlen))
+ return -EINVAL;
+
+ ret = spi_nor_lock_and_prep(nor);
+ if (ret)
+ return ret;
+
+ ret = spi_nor_mtd_otp_range_is_locked(nor, from, len);
+ if (ret < 0) {
+ goto out;
+ } else if (ret) {
+ ret = -EROFS;
+ goto out;
+ }
+
+ while (len) {
+ region = spi_nor_otp_offset_to_region(nor, from);
+ rstart = spi_nor_otp_region_start(nor, region);
+
+ ret = ops->erase(nor, rstart);
+ if (ret)
+ goto out;
+
+ len -= rlen;
+ from += rlen;
+ }
+
+out:
+ spi_nor_unlock_and_unprep(nor);
+
+ return ret;
+}
+
+static int spi_nor_mtd_otp_lock(struct mtd_info *mtd, loff_t from, size_t len)
+{
+ struct spi_nor *nor = mtd_to_spi_nor(mtd);
+ const struct spi_nor_otp_ops *ops = nor->params->otp.ops;
+ const size_t rlen = spi_nor_otp_region_len(nor);
+ unsigned int region;
+ int ret;
+
+ if (from < 0 || (from + len) > spi_nor_otp_size(nor))
+ return -EINVAL;
+
+ /* the user has to explicitly ask for whole regions */
+ if (!IS_ALIGNED(len, rlen) || !IS_ALIGNED(from, rlen))
+ return -EINVAL;
+
+ ret = spi_nor_lock_and_prep(nor);
+ if (ret)
+ return ret;
+
+ while (len) {
+ region = spi_nor_otp_offset_to_region(nor, from);
+ ret = ops->lock(nor, region);
+ if (ret)
+ goto out;
+
+ len -= rlen;
+ from += rlen;
+ }
+
+out:
+ spi_nor_unlock_and_unprep(nor);
+
+ return ret;
+}
+
+void spi_nor_set_mtd_otp_ops(struct spi_nor *nor)
+{
+ struct mtd_info *mtd = &nor->mtd;
+
+ if (!nor->params->otp.ops)
+ return;
+
+ if (WARN_ON(!is_power_of_2(spi_nor_otp_region_len(nor))))
+ return;
+
+ /*
+ * We only support user_prot callbacks (yet).
+ *
+ * Some SPI NOR flashes like Macronix ones can be ordered in two
+ * different variants. One with a factory locked OTP area and one where
+ * it is left to the user to write to it. The factory locked OTP is
+ * usually preprogrammed with an "electrical serial number". We don't
+ * support these for now.
+ */
+ mtd->_get_user_prot_info = spi_nor_mtd_otp_info;
+ mtd->_read_user_prot_reg = spi_nor_mtd_otp_read;
+ mtd->_write_user_prot_reg = spi_nor_mtd_otp_write;
+ mtd->_lock_user_prot_reg = spi_nor_mtd_otp_lock;
+ mtd->_erase_user_prot_reg = spi_nor_mtd_otp_erase;
+}