[U-Boot] [PATCH v5 17/18] spi: Add SPI NOR protection mechanism

[Fabio Estevam <festevam@gmail.com>]

From: Fabio Estevam <fabio.estevam@freescale.com>

Many SPI flashes have protection bits (BP2, BP1 and BP0) in the
status register that can protect selected regions of the SPI NOR.

Take these bits into account when performing erase operations,
making sure that the protected areas are skipped.

Tested on a mx6qsabresd:

=> sf probe
SF: Detected M25P32 with page size 256 Bytes, erase size 64 KiB, total 4 MiB
=> sf protect lock  0x3f0000 0x10000
=> sf erase 0x3f0000 0x10000
offset 0x3f0000 is protected and cannot be erased
SF: 65536 bytes @ 0x3f0000 Erased: ERROR
=> sf protect unlock  0x3f0000 0x10000
=> sf erase 0x3f0000 0x10000
SF: 65536 bytes @ 0x3f0000 Erased: OK

Signed-off-by: Fabio Estevam <fabio.estevam@freescale.com>
---
Changes since v4:
- Only apply lock operations if the SPI NOR flash ID matches STMicro (Jagan)

 common/cmd_sf.c               | 35 +++++++++++++++++++++++++
 drivers/mtd/spi/sf-uclass.c   |  8 ++++++
 drivers/mtd/spi/sf_internal.h |  8 ++++++
 drivers/mtd/spi/sf_ops.c      | 25 ++++++++++++++++++
 drivers/mtd/spi/sf_probe.c    | 61 +++++++++++++++++++++++++++++++++++++++++++
 include/spi_flash.h           | 41 +++++++++++++++++++++++++++++
 6 files changed, 178 insertions(+)

diff --git a/common/cmd_sf.c b/common/cmd_sf.c
index ac7f5df..42862d9 100644
--- a/common/cmd_sf.c
+++ b/common/cmd_sf.c
@@ -348,6 +348,37 @@ static int do_spi_flash_erase(int argc, char * const argv[])
 	return ret == 0 ? 0 : 1;
 }
 
+static int do_spi_protect(int argc, char * const argv[])
+{
+	int ret = 0;
+	loff_t start, len;
+	bool prot = false;
+
+	if (argc != 4)
+		return -1;
+
+	if (!str2off(argv[2], &start)) {
+		puts("start sector is not a valid number\n");
+		return 1;
+	}
+
+	if (!str2off(argv[3], &len)) {
+		puts("len is not a valid number\n");
+		return 1;
+	}
+
+	if (strcmp(argv[1], "lock") == 0)
+		prot = true;
+	else if (strcmp(argv[1], "unlock") == 0)
+		prot = false;
+	else
+		return -1;  /* Unknown parameter */
+
+	ret = spi_flash_protect(flash, start, len, prot);
+
+	return ret == 0 ? 0 : 1;
+}
+
 #ifdef CONFIG_CMD_SF_TEST
 enum {
 	STAGE_ERASE,
@@ -540,6 +571,8 @@ static int do_spi_flash(cmd_tbl_t *cmdtp, int flag, int argc,
 		ret = do_spi_flash_read_write(argc, argv);
 	else if (strcmp(cmd, "erase") == 0)
 		ret = do_spi_flash_erase(argc, argv);
+	else if (strcmp(cmd, "protect") == 0)
+		ret = do_spi_protect(argc, argv);
 #ifdef CONFIG_CMD_SF_TEST
 	else if (!strcmp(cmd, "test"))
 		ret = do_spi_flash_test(argc, argv);
@@ -579,5 +612,7 @@ U_BOOT_CMD(
 	"sf update addr offset|partition len	- erase and write `len' bytes from memory\n"
 	"					  at `addr' to flash at `offset'\n"
 	"					  or to start of mtd `partition'\n"
+	"sf protect lock/unlock sector len	- protect/unprotect 'len' bytes starting\n"
+	"					  at address 'sector'\n"
 	SF_TEST_HELP
 );
diff --git a/drivers/mtd/spi/sf-uclass.c b/drivers/mtd/spi/sf-uclass.c
index 350e21a..7663885 100644
--- a/drivers/mtd/spi/sf-uclass.c
+++ b/drivers/mtd/spi/sf-uclass.c
@@ -27,6 +27,14 @@ int spi_flash_erase_dm(struct udevice *dev, u32 offset, size_t len)
 	return sf_get_ops(dev)->erase(dev, offset, len);
 }
 
+int spi_flash_protect_dm(struct udevice *dev, u32 offset, size_t len, bool prot)
+{
+	if (prot)
+		return sf_get_ops(dev)->lock(dev, offset, len);
+	else
+		return sf_get_ops(dev)->unlock(dev, offset, len);
+}
+
 /*
  * TODO(sjg at chromium.org): This is an old-style function. We should remove
  * it when all SPI flash drivers use dm
diff --git a/drivers/mtd/spi/sf_internal.h b/drivers/mtd/spi/sf_internal.h
index adfcd89..db46aa8 100644
--- a/drivers/mtd/spi/sf_internal.h
+++ b/drivers/mtd/spi/sf_internal.h
@@ -177,6 +177,10 @@ int spi_flash_cmd_read_status(struct spi_flash *flash, u8 *rs);
 /* Program the status register */
 int spi_flash_cmd_write_status(struct spi_flash *flash, u8 ws);
 
+int stm_is_locked(struct spi_flash *nor, loff_t ofs, u32 len);
+int stm_lock(struct spi_flash *nor, u32 ofs, u32 len);
+int stm_unlock(struct spi_flash *nor, u32 ofs, u32 len);
+
 /* Read the config register */
 int spi_flash_cmd_read_config(struct spi_flash *flash, u8 *rc);
 
@@ -231,6 +235,10 @@ int spi_flash_read_common(struct spi_flash *flash, const u8 *cmd,
 int spi_flash_cmd_read_ops(struct spi_flash *flash, u32 offset,
 		size_t len, void *data);
 
+int spi_flash_cmd_lock_ops(struct spi_flash *flash, u32 offset, size_t len);
+int spi_flash_cmd_unlock_ops(struct spi_flash *flash, u32 offset, size_t len);
+int spi_flash_cmd_is_locked_ops(struct spi_flash *flash, u32 offset, size_t len);
+
 #ifdef CONFIG_SPI_FLASH_MTD
 int spi_flash_mtd_register(struct spi_flash *flash);
 void spi_flash_mtd_unregister(void);
diff --git a/drivers/mtd/spi/sf_ops.c b/drivers/mtd/spi/sf_ops.c
index 4ada13f..99fc7f9 100644
--- a/drivers/mtd/spi/sf_ops.c
+++ b/drivers/mtd/spi/sf_ops.c
@@ -268,6 +268,11 @@ int spi_flash_cmd_erase_ops(struct spi_flash *flash, u32 offset, size_t len)
 		return -1;
 	}
 
+	if (flash->is_locked(flash, offset, len) > 0) {
+		printf("offset 0x%x is protected and cannot be erased\n", offset);
+		return -EINVAL;
+	}
+
 	cmd[0] = flash->erase_cmd;
 	while (len) {
 		erase_addr = offset;
@@ -310,6 +315,11 @@ int spi_flash_cmd_write_ops(struct spi_flash *flash, u32 offset,
 
 	page_size = flash->page_size;
 
+	if (flash->is_locked(flash, offset, len) > 0) {
+		printf("offset 0x%x is protected and cannot be written\n", offset);
+		return -EINVAL;
+	}
+
 	cmd[0] = flash->write_cmd;
 	for (actual = 0; actual < len; actual += chunk_len) {
 		write_addr = offset;
@@ -348,6 +358,21 @@ int spi_flash_cmd_write_ops(struct spi_flash *flash, u32 offset,
 	return ret;
 }
 
+int spi_flash_cmd_lock_ops(struct spi_flash *flash, u32 offset, size_t len)
+{
+	return stm_lock(flash, offset, len);
+}
+
+int spi_flash_cmd_unlock_ops(struct spi_flash *flash, u32 offset, size_t len)
+{
+	return stm_unlock(flash, offset, len);
+}
+
+int spi_flash_cmd_is_locked_ops(struct spi_flash *flash, u32 offset, size_t len)
+{
+	return stm_is_locked(flash, offset, len);
+}
+
 int spi_flash_read_common(struct spi_flash *flash, const u8 *cmd,
 		size_t cmd_len, void *data, size_t data_len)
 {
diff --git a/drivers/mtd/spi/sf_probe.c b/drivers/mtd/spi/sf_probe.c
index c000c53..3626433 100644
--- a/drivers/mtd/spi/sf_probe.c
+++ b/drivers/mtd/spi/sf_probe.c
@@ -130,6 +130,22 @@ bank_end:
 }
 #endif
 
+int static is_stm(struct spi_slave *spi, struct spi_flash *flash)
+{
+	u8 idcode[5];
+	int ret;
+
+	/* Read the ID codes */
+	ret = spi_flash_cmd(spi, CMD_READ_ID, idcode, sizeof(idcode));
+	if (ret < 0)
+		return ret;
+
+	if (idcode[0] == SPI_FLASH_CFI_MFR_STMICRO)
+		return 1;
+	else
+		return 0;
+}
+
 static int spi_flash_validate_params(struct spi_slave *spi, u8 *idcode,
 				     struct spi_flash *flash)
 {
@@ -180,6 +196,13 @@ static int spi_flash_validate_params(struct spi_slave *spi, u8 *idcode,
 #endif
 	flash->erase = spi_flash_cmd_erase_ops;
 	flash->read = spi_flash_cmd_read_ops;
+#if defined(CONFIG_SPI_FLASH_STMICRO)
+	if (is_stm(spi, flash) > 0) {
+		flash->lock = spi_flash_cmd_lock_ops;
+		flash->unlock = spi_flash_cmd_unlock_ops;
+		flash->is_locked = spi_flash_cmd_is_locked_ops;
+	}
+#endif
 #endif
 
 	/* Compute the flash size */
@@ -482,6 +505,39 @@ int spi_flash_std_erase(struct udevice *dev, u32 offset, size_t len)
 	return spi_flash_cmd_erase_ops(flash, offset, len);
 }
 
+int spi_flash_std_lock(struct udevice *dev, u32 offset, size_t len)
+{
+	struct spi_flash *flash = dev_get_uclass_priv(dev);
+	struct spi_slave *spi = dev_get_parent_priv(dev);
+
+	if (is_stm(spi, flash) <= 0)
+		return -EOPNOTSUPP;
+
+	return spi_flash_cmd_lock_ops(flash, offset, len);
+}
+
+int spi_flash_std_unlock(struct udevice *dev, u32 offset, size_t len)
+{
+	struct spi_flash *flash = dev_get_uclass_priv(dev);
+	struct spi_slave *spi = dev_get_parent_priv(dev);
+
+	if (is_stm(spi, flash) <= 0)
+		return -EOPNOTSUPP;
+
+	return spi_flash_cmd_unlock_ops(flash, offset, len);
+}
+
+int spi_flash_std_is_locked(struct udevice *dev, u32 offset, size_t len)
+{
+	struct spi_flash *flash = dev_get_uclass_priv(dev);
+	struct spi_slave *spi = dev_get_parent_priv(dev);
+
+	if (is_stm(spi, flash) <= 0)
+		return -EOPNOTSUPP;
+
+	return spi_flash_cmd_is_locked_ops(flash, offset, len);
+}
+
 int spi_flash_std_probe(struct udevice *dev)
 {
 	struct spi_slave *slave = dev_get_parent_priv(dev);
@@ -498,6 +554,11 @@ static const struct dm_spi_flash_ops spi_flash_std_ops = {
 	.read = spi_flash_std_read,
 	.write = spi_flash_std_write,
 	.erase = spi_flash_std_erase,
+#if defined(CONFIG_SPI_FLASH_STMICRO)
+	.lock = spi_flash_std_lock,
+	.unlock = spi_flash_std_unlock,
+	.is_locked = spi_flash_std_is_locked,
+#endif
 };
 
 static const struct udevice_id spi_flash_std_ids[] = {
diff --git a/include/spi_flash.h b/include/spi_flash.h
index 4312d3d..23f30a5 100644
--- a/include/spi_flash.h
+++ b/include/spi_flash.h
@@ -104,6 +104,9 @@ struct spi_flash {
 			const void *buf);
 	int (*erase)(struct spi_flash *flash, u32 offset, size_t len);
 #endif
+	int (*lock)(struct spi_flash *flash, u32 offset, size_t len);
+	int (*unlock)(struct spi_flash *flash, u32 offset, size_t len);
+	int (*is_locked)(struct spi_flash *flash, u32 offset, size_t len);
 };
 
 struct dm_spi_flash_ops {
@@ -111,6 +114,9 @@ struct dm_spi_flash_ops {
 	int (*write)(struct udevice *dev, u32 offset, size_t len,
 		     const void *buf);
 	int (*erase)(struct udevice *dev, u32 offset, size_t len);
+	int (*lock)(struct udevice *dev, u32 offset, size_t len);
+	int (*unlock)(struct udevice *dev, u32 offset, size_t len);
+	int (*is_locked)(struct udevice *dev, u32 offset, size_t len);
 };
 
 /* Access the serial operations for a device */
@@ -152,6 +158,20 @@ int spi_flash_write_dm(struct udevice *dev, u32 offset, size_t len,
  */
 int spi_flash_erase_dm(struct udevice *dev, u32 offset, size_t len);
 
+/**
+ * spi_flash_protect_dm() - Protect/unprotect blocks of the SPI flash
+ *
+ * Note that @len must be a muiltiple of the flash sector size.
+ *
+ * @dev:	SPI flash device
+ * @offset:	Offset into device in bytes to start erasing
+ * @len:	Number of bytes to erase
+ * @prot:	True: lock the block or False: unlock the block
+ * @return 0 if OK, -ve on error
+ */
+int spi_flash_protect_dm(struct udevice *dev, u32 offset, size_t len,
+			 bool prot);
+
 int spi_flash_probe_bus_cs(unsigned int busnum, unsigned int cs,
 			   unsigned int max_hz, unsigned int spi_mode,
 			   struct udevice **devp);
@@ -183,6 +203,15 @@ static inline int spi_flash_erase(struct spi_flash *flash, u32 offset,
 	return spi_flash_erase_dm(flash->dev, offset, len);
 }
 
+static inline int spi_flash_protect(struct spi_flash *flash, loff_t ofs,
+				    u32 len, bool prot)
+{
+	if (!flash->lock)
+		return -EOPNOTSUPP;
+
+	return spi_flash_protect_dm(flash->dev, ofs, len, prot);
+}
+
 struct sandbox_state;
 
 int sandbox_sf_bind_emul(struct sandbox_state *state, int busnum, int cs,
@@ -225,6 +254,18 @@ static inline int spi_flash_erase(struct spi_flash *flash, u32 offset,
 {
 	return flash->erase(flash, offset, len);
 }
+
+static inline int spi_flash_protect(struct spi_flash *flash, u32 ofs, u32 len,
+				    bool prot)
+{
+	if (!flash->lock)
+		return -EOPNOTSUPP;
+
+	if (prot)
+		return flash->lock(flash, ofs, len);
+	else
+		return flash->unlock(flash, ofs, len);
+}
 #endif
 
 void spi_boot(void) __noreturn;
-- 
1.9.1