Re: [PATCH u-boot-mvebu v2 5/5] arm: mvebu: a37xx: Add support for reading Security OTP values

["Marek Behún" <marek.behun@nic.cz>]

On Thu, 17 Feb 2022 19:50:46 +0100
Pali Rohár <pali@kernel.org> wrote:

> It is not possible for the A53 core (on which U-Boot is running) to read it
> directly. For this purpose Marvell defined mbox API for sending OTP
> commands between CM3 and A53 cores.
> 
> Implement these Marvell fuse reading mbox commands via U-Boot fuse API.
> 
> Banks 0-43 are used for accessing Security OTP (44 rows with 67 bits via 44
> banks and words 0-2).
> 
> Note that of the 67 bits, the 3 upper bits are: 1 lock bit and 2
> auxiliary bits (meant for testing during the manufacture of the SOC, as
> I understand it).
> 
> Also note that the lock bit and the auxiliary bits are not readable
> via Marvell commands.
> 
> With CZ.NIC's commands the lock bit is readable.
> 
> Write support is not implemented yet.
> 
> Signed-off-by: Pali Rohár <pali@kernel.org>
> ---
>  arch/arm/mach-mvebu/armada3700/efuse.c | 38 ++++++++++++++++++++++++--
>  1 file changed, 36 insertions(+), 2 deletions(-)
> 
> diff --git a/arch/arm/mach-mvebu/armada3700/efuse.c b/arch/arm/mach-mvebu/armada3700/efuse.c
> index 03778f17ea49..fcf6edd08ce1 100644
> --- a/arch/arm/mach-mvebu/armada3700/efuse.c
> +++ b/arch/arm/mach-mvebu/armada3700/efuse.c
> @@ -8,6 +8,7 @@
>  #include <common.h>
>  #include <asm/io.h>
>  #include <linux/delay.h>
> +#include <mach/mbox.h>
>  #include <mach/soc.h>
>  
>  #define OTP_NB_REG_BASE		((void __iomem *)MVEBU_REGISTER(0x12600))
> @@ -77,6 +78,40 @@ static void otp_read_parallel(void __iomem *base, u32 *data, u32 count)
>  	}
>  }
>  
> +static int rwtm_otp_read(u8 row, u32 word, u32 *data)
> +{
> +	u32 out[3];
> +	u32 in[2];
> +	int res = -EINVAL;
> +
> +	if (word < 2) {
> +		/*
> +		 * MBOX_CMD_OTP_READ_32B command is supported by Marvell
> +		 * fuse.bin firmware and also by new CZ.NIC wtmi firmware.
> +		 * This command returns raw bits without ECC corrections.
> +		 * It does not provide access to the lock bit.
> +		 */
> +		in[0] = row;
> +		in[1] = word * 32;
> +		res = mbox_do_cmd(MBOX_CMD_OTP_READ_32B, in, 2, out, 2);
> +		if (!res)
> +			*data = out[0];
> +	} else if (word == 2) {
> +		/*
> +		 * MBOX_CMD_OTP_READ command is supported only by CZ.NIC wtmi
> +		 * firmware and provide
nitpick: *provides

Reviewed-by: Marek Behún <marek.behun@nic.cz>