1 files changed, 377 insertions, 0 deletions
diff --git a/drivers/mtd/spi-nor/otp.c b/drivers/mtd/spi-nor/otp.c
new file mode 100644
index 000000000000..fcf38d260345
--- /dev/null
+++ b/drivers/mtd/spi-nor/otp.c
@@ -0,0 +1,377 @@
+// 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 OTP data
+ * @nor:	pointer to 'struct spi_nor'
+ * @from:       offset to read from
+ * @len:        number of bytes to read
+ * @buf:        pointer to dst buffer
+ *
+ * Read OTP data from one region by using the SPINOR_OP_RSECR commands. This
+ * method is used on GigaDevice and Winbond flashes.
+ *
+ * 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_width, read_opcode, read_dummy;
+	struct spi_mem_dirmap_desc *rdesc;
+	enum spi_nor_protocol read_proto;
+	int ret;
+
+	read_opcode = nor->read_opcode;
+	addr_width = nor->addr_width;
+	read_dummy = nor->read_dummy;
+	read_proto = nor->read_proto;
+	rdesc = nor->dirmap.rdesc;
+
+	nor->read_opcode = SPINOR_OP_RSECR;
+	nor->addr_width = 3;
+	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_width = addr_width;
+	nor->read_dummy = read_dummy;
+	nor->read_proto = read_proto;
+	nor->dirmap.rdesc = rdesc;
+
+	return ret;
+}
+
+/**
+ * spi_nor_otp_write_secr() - write OTP data
+ * @nor:        pointer to 'struct spi_nor'
+ * @to:         offset to write to
+ * @len:        number of bytes to write
+ * @buf:        pointer to src buffer
+ *
+ * Write OTP data to one region by using the SPINOR_OP_PSECR commands. This
+ * method is used on GigaDevice and Winbond flashes.
+ *
+ * Please note, the write must not span multiple OTP regions.
+ *
+ * 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_width, program_opcode;
+	int ret, written;
+
+	program_opcode = nor->program_opcode;
+	addr_width = nor->addr_width;
+	write_proto = nor->write_proto;
+	wdesc = nor->dirmap.wdesc;
+
+	nor->program_opcode = SPINOR_OP_PSECR;
+	nor->addr_width = 3;
+	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 OTP region.
+	 */
+	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_width = addr_width;
+	nor->write_proto = write_proto;
+	nor->dirmap.wdesc = wdesc;
+
+	return ret ?: written;
+}
+
+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_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;
+
+	ret = spi_nor_lock_and_prep(nor);
+	if (ret)
+		return ret;
+
+	/* don't access beyond the end */
+	total_len = min_t(size_t, total_len, spi_nor_otp_size(nor) - ofs);
+
+	*retlen = 0;
+	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_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_otp_init(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;
+}