[U-Boot] [PATCH 3/5] Add fuse API and commands

[Dirk Behme]

On 22.08.2012 13:11, Benoît Thébaudeau wrote:
> Hi Dirk,
>
> On Wednesday, August 22, 2012 12:43:05 PM, Dirk Behme wrote:
>> On 14.08.2012 14:52, Benoît Thébaudeau wrote:
>>> This can be useful for fuse-like hardware, OTP SoC options, etc.
>>
>> For i.MX6, I have a port of the OTP support from Freescale's U-Boot
>> to
>> our mainline U-Boot in the queue [1].
>>
>> As I don't have the overview over the various i.MXxx SoCs and don't
>> understand much of this patch below: Should this implement the same
>> functionality like my patch [1] for i.MX6?
>>
>> Or shall I send my patch [1] to this mailing list for official review
>> because the functionality here and there is orthogonal?
>>
>> Thanks
>>
>> Dirk
>>
>> [1]
>> https://github.com/dirkbehme/u-boot-imx6/commit/da718b338a79af160f7b7e542fe97b24edbfc36a
>
> This OTP IP is different from the IIM IP of other i.MXs, so having a different
> driver for it is fine.
>
> What you can do is implement in your driver the fuse API

You mean

http://lists.denx.de/pipermail/u-boot/2012-August/130904.html

here, correct?

>that I've defined in
> this series. In that way, you could drop your common/cmd_imxotp.c and use the
> commands from this series.

Let's see how this fits to i.MX6:

My understanding is that the i.MX6 has 128 fuse 'registers' (#define 
IMX_OTP_ADDR_MAX 0x7F), each containing 32 fuses/bits. These 
fuses/bits can be written from 0 -> 1 once.

Looking at your API [2] we could set 'bank' to 0 and interpret 'row' 
as the 'register' number. That might fit. Doing this, 
fuse_read_bit/row() and fuse_prog_bit/row() could be used for i.MX6.

 From i.MX6 point of view, as I don't know your use case, I'm not sure 
what fuse_sense_bit/row() and fuse_override_bit/row() might be good for?

Anybody else: Does this make sense? Or should we keep the i.MX6 
specific common/cmd_imxotp.c (see [1] above)?.

Best regards

Dirk

[2]

+ * Read/Sense/Program/Override interface:
+ *   bank:    Fuse bank
+ *   row:     Fuse row within the bank
+ *   bit:     Fuse bit within the row
+ *   val:     Value to read/write
+ *
+ *   Returns: 0 on success, not 0 on failure
+ */
+int fuse_read_bit(u32 bank, u32 row, u32 bit, u32 *val);
+int fuse_read_row(u32 bank, u32 row, u32 *val);
+int fuse_sense_bit(u32 bank, u32 row, u32 bit, u32 *val);
+int fuse_sense_row(u32 bank, u32 row, u32 *val);
+int fuse_prog_bit(u32 bank, u32 row, u32 bit);
+int fuse_prog_row(u32 bank, u32 row, u32 val);
+int fuse_override_bit(u32 bank, u32 row, u32 bit, u32 val);
+int fuse_override_row(u32 bank, u32 row, u32 val);