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.

Introduce the CONFIG_SF_STM_PROTECT option that can be selected by systems that want to protect regions of SPI NOR flash using the same programming model as in the ST Micro SPI NOR flashes, like for example the M25P32.

Based on the implementation from Brian Norris computersforpeace@gmail.com for the Linux kernel: https://patchwork.ozlabs.org/patch/513041/

Tested on a mx6qsabresd:

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

Signed-off-by: Fabio Estevam fabio.estevam@freescale.com ---

README | 12 +++ common/cmd_sf.c | 30 +++++++ drivers/mtd/spi/sf_internal.h | 6 -- drivers/mtd/spi/sf_ops.c | 188 ++++++++++++++++++++++++++++++++++++++++++ include/spi_flash.h | 25 +++++- 5 files changed, 253 insertions(+), 8 deletions(-)

diff --git a/README b/README index a13705a..3411ea9 100644 --- a/README +++ b/README @@ -3068,6 +3068,18 @@ CBFS (Coreboot Filesystem) support memories can be connected with a given cs line. Currently Xilinx Zynq qspi supports these type of connections.

+ CONFIG_SF_STM_PROTECT + + Enable the built-in protection mechanism provided by the + BP2, BP1 and BP0 bits from the status register present + on ST-Micro flashes such as M25P32. Please refer to the + M25P32 datasheet to understand how to program these bits + in order to protect a selected region of the SPI NOR flash. + This same bit protection programming model applies to SPI + NOR flashes from other manufacturers such as: + - Micron M25P32 + - SST SST25V32B + - SystemACE Support: CONFIG_SYSTEMACE

diff --git a/common/cmd_sf.c b/common/cmd_sf.c index ac7f5df..df78813 100644 --- a/common/cmd_sf.c +++ b/common/cmd_sf.c @@ -348,6 +348,28 @@ static int do_spi_flash_erase(int argc, char * const argv[]) return ret == 0 ? 0 : 1; }

+#ifdef CONFIG_SF_STM_PROTECT +static int do_spi_protect(int argc, char * const argv[]) +{ + int start, len, ret = 0; + + if (argc != 4) + return -1; + + start = simple_strtoull(argv[2], NULL, 16); + len = simple_strtoull(argv[3], NULL, 16); + + if (strcmp(argv[1], "on") == 0) + ret = stm_lock(flash, start, len); + else if (strcmp(argv[1], "off") == 0) + ret = stm_unlock(flash, start, len); + else + return -1; /* Unknown parameter */ + + return ret == 0 ? 0 : 1; +} +#endif + #ifdef CONFIG_CMD_SF_TEST enum { STAGE_ERASE, @@ -540,6 +562,10 @@ 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); +#ifdef CONFIG_SF_STM_PROTECT + else if (strcmp(cmd, "protect") == 0) + ret = do_spi_protect(argc, argv); +#endif #ifdef CONFIG_CMD_SF_TEST else if (!strcmp(cmd, "test")) ret = do_spi_flash_test(argc, argv); @@ -579,5 +605,9 @@ 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" +#ifdef CONFIG_SF_STM_PROTECT + "sf protect on/off sector len - protect/unprotect 'len' bytes starting\n" + " at address 'sector'\n" +#endif SF_TEST_HELP ); diff --git a/drivers/mtd/spi/sf_internal.h b/drivers/mtd/spi/sf_internal.h index 9c95d56..e66a62b 100644 --- a/drivers/mtd/spi/sf_internal.h +++ b/drivers/mtd/spi/sf_internal.h @@ -162,12 +162,6 @@ int spi_flash_cmd_write(struct spi_slave *spi, const u8 *cmd, size_t cmd_len, /* Flash erase(sectors) operation, support all possible erase commands */ int spi_flash_cmd_erase_ops(struct spi_flash *flash, u32 offset, size_t len);

-/* Read the status register */ -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); - /* Read the config register */ int spi_flash_cmd_read_config(struct spi_flash *flash, u8 *rc);

diff --git a/drivers/mtd/spi/sf_ops.c b/drivers/mtd/spi/sf_ops.c index 900ec1f..5c7caca 100644 --- a/drivers/mtd/spi/sf_ops.c +++ b/drivers/mtd/spi/sf_ops.c @@ -573,3 +573,191 @@ int sst_write_bp(struct spi_flash *flash, u32 offset, size_t len, return ret; } #endif + +#ifdef CONFIG_SF_STM_PROTECT +#define SR_BP0 BIT(2) /* Block protect 0 */ +#define SR_BP1 BIT(3) /* Block protect 1 */ +#define SR_BP2 BIT(4) /* Block protect 2 */ + +static void stm_get_locked_range(struct spi_flash *nor, u8 sr, loff_t *ofs, + u32 *len) +{ + u8 mask = SR_BP2 | SR_BP1 | SR_BP0; + int shift = ffs(mask) - 1; + int pow; + + if (!(sr & mask)) { + /* No protection */ + *ofs = 0; + *len = 0; + } else { + pow = ((sr & mask) ^ mask) >> shift; + *len = nor->size >> pow; + *ofs = nor->size - *len; + } +} + +/* + * Return 1 if the entire region is locked, 0 otherwise + */ +static int stm_is_locked_sr(struct spi_flash *nor, loff_t ofs, u32 len, + u8 sr) +{ + loff_t lock_offs; + u32 lock_len; + + stm_get_locked_range(nor, sr, &lock_offs, &lock_len); + + return (ofs + len <= lock_offs + lock_len) && (ofs >= lock_offs); +} + +/* + * Check if a region of the flash is (completely) locked. See stm_lock() for + * more info. + * + * Returns 1 if entire region is locked, 0 if any portion is unlocked, and + * negative on errors. + */ +int stm_is_locked(struct spi_flash *nor, loff_t ofs, u32 len) +{ + int status; + u8 sr; + + status = spi_flash_cmd_read_status(nor, &sr); + if (status < 0) + return status; + + return stm_is_locked_sr(nor, ofs, len, sr); +} + +/* + * Lock a region of the flash. Compatible with ST Micro and similar flash. + * Supports only the block protection bits BP{0,1,2} in the status register + * (SR). Does not support these features found in newer SR bitfields: + * - TB: top/bottom protect - only handle TB=0 (top protect) + * - SEC: sector/block protect - only handle SEC=0 (block protect) + * - CMP: complement protect - only support CMP=0 (range is not complemented) + * + * Sample table portion for 8MB flash (Winbond w25q64fw): + * + * SEC | TB | BP2 | BP1 | BP0 | Prot Length | Protected Portion + * -------------------------------------------------------------------------- + * X | X | 0 | 0 | 0 | NONE | NONE + * 0 | 0 | 0 | 0 | 1 | 128 KB | Upper 1/64 + * 0 | 0 | 0 | 1 | 0 | 256 KB | Upper 1/32 + * 0 | 0 | 0 | 1 | 1 | 512 KB | Upper 1/16 + * 0 | 0 | 1 | 0 | 0 | 1 MB | Upper 1/8 + * 0 | 0 | 1 | 0 | 1 | 2 MB | Upper 1/4 + * 0 | 0 | 1 | 1 | 0 | 4 MB | Upper 1/2 + * X | X | 1 | 1 | 1 | 8 MB | ALL + * + * Returns negative on errors, 0 on success. + */ +int stm_lock(struct spi_flash *nor, u32 ofs, u32 len) +{ + u8 status_old, status_new; + u8 mask = SR_BP2 | SR_BP1 | SR_BP0; + u8 shift = ffs(mask) - 1, pow, val; + + spi_flash_cmd_read_status(nor, &status_old); + + /* SPI NOR always locks to the end */ + if (ofs + len != nor->size) { + /* Does combined region extend to end? */ + if (!stm_is_locked_sr(nor, ofs + len, nor->size - ofs - len, + status_old)) + return -EINVAL; + len = nor->size - ofs; + } + + /* + * Need smallest pow such that: + * + * 1 / (2^pow) <= (len / size) + * + * so (assuming power-of-2 size) we do: + * + * pow = ceil(log2(size / len)) = log2(size) - floor(log2(len)) + */ + pow = __ilog2(nor->size) - __ilog2(len); + val = mask - (pow << shift); + if (val & ~mask) + return -EINVAL; + + /* Don't "lock" with no region! */ + if (!(val & mask)) + return -EINVAL; + + status_new = (status_old & ~mask) | val; + + /* Only modify protection if it will not unlock other areas */ + if ((status_new & mask) <= (status_old & mask)) + return -EINVAL; + + spi_flash_cmd_write_status(nor, status_new); + + return 0; +} + +/* + * Unlock a region of the flash. See stm_lock() for more info + * + * Returns negative on errors, 0 on success. + */ +int stm_unlock(struct spi_flash *nor, u32 ofs, u32 len) +{ + uint8_t status_old, status_new; + u8 mask = SR_BP2 | SR_BP1 | SR_BP0; + u8 shift = ffs(mask) - 1, pow, val; + + spi_flash_cmd_read_status(nor, &status_old); + + /* Cannot unlock; would unlock larger region than requested */ + if (stm_is_locked_sr(nor, status_old, ofs - nor->erase_size, + nor->erase_size)) + return -EINVAL; + /* + * Need largest pow such that: + * + * 1 / (2^pow) >= (len / size) + * + * so (assuming power-of-2 size) we do: + * + * pow = floor(log2(size / len)) = log2(size) - ceil(log2(len)) + */ + pow = __ilog2(nor->size) - order_base_2(nor->size - (ofs + len)); + if (ofs + len == nor->size) { + val = 0; /* fully unlocked */ + } else { + val = mask - (pow << shift); + /* Some power-of-two sizes are not supported */ + if (val & ~mask) + return -EINVAL; + } + + status_new = (status_old & ~mask) | val; + + /* Only modify protection if it will not lock other areas */ + if ((status_new & mask) >= (status_old & mask)) + return -EINVAL; + + spi_flash_cmd_write_status(nor, status_new); + + return 0; +} +#else +int stm_is_locked(struct spi_flash *nor, loff_t ofs, u32 len) +{ + return 0; +} + +int stm_lock(struct spi_flash *nor, u32 ofs, u32 len) +{ + return 0; +} + +int stm_unlock(struct spi_flash *nor, u32 ofs, u32 len) +{ + return 0; +} +#endif /* CONFIG_SF_STM_PROTECT */ diff --git a/include/spi_flash.h b/include/spi_flash.h index 3b2d555..434323e 100644 --- a/include/spi_flash.h +++ b/include/spi_flash.h @@ -115,6 +115,17 @@ struct dm_spi_flash_ops { int (*erase)(struct udevice *dev, u32 offset, size_t len); };

+ +/* Read the status register */ +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); + /* Access the serial operations for a device */ #define sf_get_ops(dev) ((struct dm_spi_flash_ops *)(dev)->driver->ops)

@@ -219,13 +230,23 @@ static inline int spi_flash_read(struct spi_flash *flash, u32 offset, static inline int spi_flash_write(struct spi_flash *flash, u32 offset, size_t len, const void *buf) { - return flash->write(flash, offset, len, buf); + if (stm_is_locked(flash, offset, len) > 0) { + printf("offset 0x%x is protected and cannot be written\n", offset); + return -EINVAL; + } else { + return flash->write(flash, offset, len, buf); + } }

static inline int spi_flash_erase(struct spi_flash *flash, u32 offset, size_t len) { - return flash->erase(flash, offset, len); + if (stm_is_locked(flash, offset, len) > 0) { + printf("offset 0x%x is protected and cannot be erased\n", offset); + return -EINVAL; + } else { + return flash->erase(flash, offset, len); + } } #endif