From: Brian Norris computersforpeace@gmail.com
As per following Sections in ONFI Spec, NAND_CMD_READID should use only lower 8-bit for transfering command, address and data even on x16 NAND device.
*Section: Target Initialization" "The Read ID and Read Parameter Page commands only use the lower 8-bits of the data bus. The host shall not issue commands that use a word data width on x16 devices until the host determines the device supports a 16-bit data bus width in the parameter page."
*Section: Bus Width Requirements* "When the host supports a 16-bit bus width, only data is transferred at the 16-bit width. All address and command line transfers shall use only the lower 8-bits of the data bus. During command transfers, the host may place any value on the upper 8-bits of the data bus. During address transfers, the host shall set the upper 8-bits of the data bus to 00h."
Thus porting following commit from linux-kernel to ensure that column address is not altered to align to x16 bus when issuing NAND_CMD_READID command.
commit 3dad2344e92c6e1aeae42df1c4824f307c51bcc7 mtd: nand: force NAND_CMD_READID onto 8-bit bus Author: Brian Norris computersforpeace@gmail.com (preserving authorship)
The NAND command helpers tend to automatically shift the column address for x16 bus devices, since most commands expect a word address, not a byte address. The Read ID command, however, expects an 8-bit address (i.e., 0x00, 0x20, or 0x40 should not be translated to 0x00, 0x10, or 0x20).
This fixes the column address for a few drivers which imitate the nand_base defaults.
Signed-off-by: Pekon Gupta pekon@ti.com --- drivers/mtd/nand/am335x_spl_bch.c | 2 +- drivers/mtd/nand/atmel_nand.c | 2 +- drivers/mtd/nand/nand_base.c | 6 ++++-- drivers/mtd/nand/nand_spl_simple.c | 2 +- include/linux/mtd/nand.h | 10 ++++++++++ 5 files changed, 17 insertions(+), 5 deletions(-)
diff --git a/drivers/mtd/nand/am335x_spl_bch.c b/drivers/mtd/nand/am335x_spl_bch.c index c84851b..86572a2 100644 --- a/drivers/mtd/nand/am335x_spl_bch.c +++ b/drivers/mtd/nand/am335x_spl_bch.c @@ -55,7 +55,7 @@ static int nand_command(int block, int page, uint32_t offs, }
/* Shift the offset from byte addressing to word addressing. */ - if (this->options & NAND_BUSWIDTH_16) + if ((this->options & NAND_BUSWIDTH_16) && !nand_opcode_8bits(cmd)) offs >>= 1;
/* Set ALE and clear CLE to start address cycle */ diff --git a/drivers/mtd/nand/atmel_nand.c b/drivers/mtd/nand/atmel_nand.c index e1fc48f..e73834d 100644 --- a/drivers/mtd/nand/atmel_nand.c +++ b/drivers/mtd/nand/atmel_nand.c @@ -1195,7 +1195,7 @@ static int nand_command(int block, int page, uint32_t offs, u8 cmd)
hwctrl(&mtd, cmd, NAND_CTRL_CLE | NAND_CTRL_CHANGE);
- if (this->options & NAND_BUSWIDTH_16) + if ((this->options & NAND_BUSWIDTH_16) && !nand_opcode_8bits(cmd)) offs >>= 1;
hwctrl(&mtd, offs & 0xff, NAND_CTRL_ALE | NAND_CTRL_CHANGE); diff --git a/drivers/mtd/nand/nand_base.c b/drivers/mtd/nand/nand_base.c index 5d3232c..376976d 100644 --- a/drivers/mtd/nand/nand_base.c +++ b/drivers/mtd/nand/nand_base.c @@ -575,7 +575,8 @@ static void nand_command(struct mtd_info *mtd, unsigned int command, /* Serially input address */ if (column != -1) { /* Adjust columns for 16 bit buswidth */ - if (chip->options & NAND_BUSWIDTH_16) + if ((chip->options & NAND_BUSWIDTH_16) && + !nand_opcode_8bits(command)) column >>= 1; chip->cmd_ctrl(mtd, column, ctrl); ctrl &= ~NAND_CTRL_CHANGE; @@ -668,7 +669,8 @@ static void nand_command_lp(struct mtd_info *mtd, unsigned int command, /* Serially input address */ if (column != -1) { /* Adjust columns for 16 bit buswidth */ - if (chip->options & NAND_BUSWIDTH_16) + if ((chip->options & NAND_BUSWIDTH_16) && + !nand_opcode_8bits(command)) column >>= 1; chip->cmd_ctrl(mtd, column, ctrl); ctrl &= ~NAND_CTRL_CHANGE; diff --git a/drivers/mtd/nand/nand_spl_simple.c b/drivers/mtd/nand/nand_spl_simple.c index cead4b5..e1ddead 100644 --- a/drivers/mtd/nand/nand_spl_simple.c +++ b/drivers/mtd/nand/nand_spl_simple.c @@ -78,7 +78,7 @@ static int nand_command(int block, int page, uint32_t offs, }
/* Shift the offset from byte addressing to word addressing. */ - if (this->options & NAND_BUSWIDTH_16) + if ((this->options & NAND_BUSWIDTH_16) && !nand_opcode_8bits(command)) offs >>= 1;
/* Begin command latch cycle */ diff --git a/include/linux/mtd/nand.h b/include/linux/mtd/nand.h index 0546565..4be8858 100644 --- a/include/linux/mtd/nand.h +++ b/include/linux/mtd/nand.h @@ -719,4 +719,14 @@ static inline int onfi_get_sync_timing_mode(struct nand_chip *chip) } #endif
+/** + * Check if the opcode's address should be sent only on the lower 8 bits + * @command: opcode to check + */ +static inline int nand_opcode_8bits(unsigned int command) +{ + return command == NAND_CMD_READID; +} + + #endif /* __LINUX_MTD_NAND_H */