[2/4] Add support for SPI-NOR Macronix OTP.

diff --git a/drivers/mtd/spi-nor/macronix.c b/drivers/mtd/spi-nor/macronix.c
index ea6be95e75a5..f210231468a6 100644
--- a/drivers/mtd/spi-nor/macronix.c
+++ b/drivers/mtd/spi-nor/macronix.c
@@ -8,6 +8,180 @@ 
 
 #include "core.h"
 
+/**
+ * macronix_nor_otp_enter() - Send Enter Secured OTP instruction to the chip.
+ * @nor:	pointer to 'struct spi_nor'.
+ *
+ * Return: 0 on success, -errno otherwise.
+ */
+static int macronix_nor_otp_enter(struct spi_nor *nor)
+{
+	int error;
+
+	error = spi_nor_send_cmd(nor, SPINOR_OP_ENSO);
+
+	if (error)
+		dev_dbg(nor->dev, "error %d on Macronix Enter Secured OTP\n", error);
+
+	return error;
+}
+
+/**
+ * macronix_nor_otp_exit() - Send Exit Secured OTP instruction to the chip.
+ * @nor:	pointer to 'struct spi_nor'.
+ *
+ * Return: 0 on success, -errno otherwise.
+ */
+static int macronix_nor_otp_exit(struct spi_nor *nor)
+{
+	int error;
+
+	error = spi_nor_send_cmd(nor, SPINOR_OP_EXSO);
+
+	if (error)
+		dev_dbg(nor->dev, "error %d on Macronix Enter Secured OTP\n", error);
+
+	return error;
+}
+
+/**
+ * macronix_nor_otp_read() - 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
+ *
+ * Return: number of bytes read successfully, -errno otherwise
+ */
+static int macronix_nor_otp_read(struct spi_nor *nor, loff_t addr, size_t len, u8 *buf)
+{
+	int ret, error;
+
+	error = macronix_nor_otp_enter(nor);
+	if (error)
+		return error;
+
+	ret = spi_nor_read_data(nor, addr, len, buf);
+
+	error = macronix_nor_otp_exit(nor);
+
+	if (ret < 0)
+		dev_dbg(nor->dev, "error %d on Macronix read OTP data\n", ret);
+	else if (error)
+		return error;
+
+	return ret;
+}
+
+/**
+ * macronix_nor_otp_write() - 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
+ *
+ * Return: number of bytes written successfully, -errno otherwise
+ */
+static int macronix_nor_otp_write(struct spi_nor *nor, loff_t addr, size_t len, const u8 *buf)
+{
+	int error, ret = 0;
+
+	error = macronix_nor_otp_enter(nor);
+	if (error)
+		return error;
+
+	error = spi_nor_write_enable(nor);
+	if (error)
+		goto otp_write_err;
+
+	ret = spi_nor_write_data(nor, addr, len, buf);
+	if (ret < 0) {
+		dev_dbg(nor->dev, "error %d on Macronix write OTP data\n", ret);
+		goto otp_write_err;
+	}
+
+	error = spi_nor_wait_till_ready(nor);
+	if (error)
+		dev_dbg(nor->dev, "error %d on Macronix waiting write OTP finish\n", error);
+
+otp_write_err:
+
+	error = macronix_nor_otp_exit(nor);
+
+	return ret;
+}
+
+/**
+ * macronix_nor_otp_lock() - lock the OTP region
+ * @nor:        pointer to 'struct spi_nor'
+ * @region:     OTP region
+ *
+ * Return: 0 on success, -errno otherwise.
+ */
+static int macronix_nor_otp_lock(struct spi_nor *nor, unsigned int region)
+{
+	int error;
+	u8 *rdscur = nor->bouncebuf;
+
+	error = spi_nor_read_reg(nor, SPINOR_OP_RDSCUR, 1);
+	if (error) {
+		dev_dbg(nor->dev, "error %d on read security register\n", error);
+		return error;
+	}
+
+	switch (region) {
+	case 0: /* Lock 1st 4K-bit region */
+		if (rdscur[0] & SEC_REG_LDSO)
+			return 0; /* Already locked */
+		rdscur[0] |= SEC_REG_LDSO;
+		break;
+	case 1: /* Lock 2nd 4K-bit region */
+		if (rdscur[0] & SEC_REG_LDS1)
+			return 0; /* Already locked */
+		rdscur[0] |= SEC_REG_LDS1;
+		break;
+	default:
+		return 0; /* Unknown region */
+	}
+
+	error = spi_nor_write_reg(nor, SPINOR_OP_WRSCUR, 1);
+	if (error)
+		dev_dbg(nor->dev, "error %d on update security register\n", error);
+
+	return error;
+}
+
+/**
+ * macronix_nor_otp_is_locked() - get the OTP region lock status
+ * @nor:        pointer to 'struct spi_nor'
+ * @region:     OTP region
+ *
+ * Return: 0 on success, -errno otherwise.
+ */
+static int macronix_nor_otp_is_locked(struct spi_nor *nor, unsigned int region)
+{
+	int ret;
+	u8 *rdscur = nor->bouncebuf;
+
+	ret = spi_nor_read_reg(nor, SPINOR_OP_RDSCUR, 1);
+	if (ret) {
+		dev_dbg(nor->dev, "error %d on read security register\n", ret);
+		return ret;
+	}
+
+	switch (region) {
+	case 0: /* 1st 4K-bit region */
+		ret = (rdscur[0] & SEC_REG_LDSO) > 0;
+		break;
+	case 1: /* 2nd 4K-bit region */
+		ret = (rdscur[0] & SEC_REG_LDS1) > 0;
+		break;
+	default: /* Unknown region */
+		break;
+	}
+	return ret;
+}
+
 static int
 mx25l25635_post_bfpt_fixups(struct spi_nor *nor,
 			    const struct sfdp_parameter_header *bfpt_header,
@@ -190,8 +364,19 @@  static void macronix_nor_default_init(struct spi_nor *nor)
 	nor->params->quad_enable = spi_nor_sr1_bit6_quad_enable;
 }
 
+static const struct spi_nor_otp_ops macronix_nor_otp_ops = {
+	.read = macronix_nor_otp_read,
+	.write = macronix_nor_otp_write,
+	/* .erase = Macronix OTP do not support erase, */
+	.lock = macronix_nor_otp_lock,
+	.is_locked = macronix_nor_otp_is_locked,
+};
+
 static int macronix_nor_late_init(struct spi_nor *nor)
 {
+	if (nor->params->otp.org->n_regions)
+		nor->params->otp.ops = &macronix_nor_otp_ops;
+
 	if (!nor->params->set_4byte_addr_mode)
 		nor->params->set_4byte_addr_mode = spi_nor_set_4byte_addr_mode_en4b_ex4b;
 
diff --git a/include/linux/mtd/spi-nor.h b/include/linux/mtd/spi-nor.h
index cdcfe0fd2e7d..f5965f90f51e 100644
--- a/include/linux/mtd/spi-nor.h
+++ b/include/linux/mtd/spi-nor.h
@@ -81,6 +81,16 @@ 
 #define SPINOR_OP_BP		0x02	/* Byte program */
 #define SPINOR_OP_AAI_WP	0xad	/* Auto address increment word program */
 
+/* Used by Macronix OTP. */
+#define SPINOR_OP_RDSCUR	0x2b	/* read security register */
+#define SPINOR_OP_WRSCUR	0x2f	/* write security register */
+#define SPINOR_OP_ENSO		0xb1	/* enter secured OTP */
+#define SPINOR_OP_EXSO		0xc1	/* exit secured OTP */
+
+/* Security register */
+#define SEC_REG_LDSO		BIT(1)  /* lock-down bit 1st 4K-bit */
+#define SEC_REG_LDS1		BIT(0)  /* lock-down bit 2nd 4K-bit */
+
 /* Used for Macronix and Winbond flashes. */
 #define SPINOR_OP_EN4B		0xb7	/* Enter 4-byte mode */
 #define SPINOR_OP_EX4B		0xe9	/* Exit 4-byte mode */