Re: [PATCH] arm: mvebu: a37xx: Add support for writing Security OTP values

Stefan Roese
2022-04-21T14:14:17Z

On 4/7/22 11:32, Pali Rohár wrote:
> Implement write support for Security OTP values via mailbox API commands
> MBOX_CMD_OTP_WRITE_32B and MBOX_CMD_OTP_WRITE.
>
> Write support for North and South Bridge OTPs are not implemented as these
> OTPs are already burned in factory with some data.
>
> Signed-off-by: Pali Rohár <pali@kernel.org>
> ---
> This patch depends on series which implements read support for A3720 OTP:
> https://patchwork.ozlabs.org/project/uboot/list/?series=287578&state=*
>
> Stefan, what do you think, should be enable write support by default. Or
> should it be hidden under some other CONFIG option? Becaue currently
> CONFIG_CMD_FUSE enable both read and write support (or what driver
> implements).

Frankly, I missed answering this question until now. Yes, let's enable
write support:

Applied to u-boot-marvell/master

Thanks,
Stefan

> ---
> arch/arm/mach-mvebu/armada3700/efuse.c | 50 ++++++++++++++++++++++++--
> 1 file changed, 48 insertions(+), 2 deletions(-)
>
> diff --git a/arch/arm/mach-mvebu/armada3700/efuse.c b/arch/arm/mach-mvebu/armada3700/efuse.c
> index 50c73f36c565..07d5f394354c 100644
> --- a/arch/arm/mach-mvebu/armada3700/efuse.c
> +++ b/arch/arm/mach-mvebu/armada3700/efuse.c
> @@ -113,6 +113,41 @@ static int rwtm_otp_read(u8 row, u32 word, u32 *data)
> return res;
> }
>
> +static int rwtm_otp_write(u8 row, u32 word, u32 data)
> +{
> + u32 in[4];
> + int res = -EINVAL;
> +
> + if (word < 2) {
> + /*
> + * MBOX_CMD_OTP_WRITE_32B command is supported by Marvell
> + * fuse.bin firmware and also by new CZ.NIC wtmi firmware.
> + * This command writes only selected bits to OTP and does
> + * not calculate ECC bits. It does not allow to write the
> + * lock bit.
> + */
> + in[0] = row;
> + in[1] = word * 32;
> + in[2] = data;
> + res = mbox_do_cmd(MBOX_CMD_OTP_WRITE_32B, in, 3, NULL, 0);
> + } else if (word == 2 && !(data & ~0x1)) {
> + /*
> + * MBOX_CMD_OTP_WRITE command is supported only by new CZ.NIC
> + * wtmi firmware and allows to write any bit to OTP, including
> + * the lock bit. It does not calculate or write ECC bits too.
> + * For compatibility with Marvell fuse.bin firmware, use this
> + * command only for writing the lock bit.
> + */
> + in[0] = row;
> + in[1] = 0;
> + in[2] = 0;
> + in[3] = data;
> + res = mbox_do_cmd(MBOX_CMD_OTP_WRITE, in, 4, NULL, 0);
> + }
> +
> + return res;
> +}
> +
> /*
> * Banks 0-43 are used for accessing Security OTP (44 rows with 67 bits via 44 banks and words 0-2)
> * Bank 44 is used for accessing North Bridge OTP (69 bits via words 0-2)
> @@ -154,8 +189,19 @@ int fuse_read(u32 bank, u32 word, u32 *val)
>
> int fuse_prog(u32 bank, u32 word, u32 val)
> {
> - /* TODO: not implemented yet */
> - return -ENOSYS;
> + if (bank <= RWTM_MAX_BANK) {
> + if (word >= RWTM_ROW_WORDS)
> + return -EINVAL;
> + return rwtm_otp_write(bank, word, val);
> + } else if (bank == OTP_NB_BANK) {
> + /* TODO: not implemented yet */
> + return -ENOSYS;
> + } else if (bank == OTP_SB_BANK) {
> + /* TODO: not implemented yet */
> + return -ENOSYS;
> + } else {
> + return -EINVAL;
> + }
> }
>
> int fuse_sense(u32 bank, u32 word, u32 *val)

Viele Grüße,
Stefan Roese

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