[PATCH] drivers: tpm2: update reset gpio semantics

[Michal Simek]

On 5/28/21 6:18 PM, Bruno Thomsen wrote:
> Den tor. 27. maj 2021 kl. 09.15 skrev Michal Simek <michal.simek at xilinx.com>:
>>
>>
>>
>> On 5/26/21 9:57 PM, Jorge Ramirez-Ortiz wrote:
>>> Use the more generic reset-gpios propery name.
>>>
>>> Signed-off-by: Jorge Ramirez-Ortiz <jorge at foundries.io>
>>> ---
>>>  doc/device-tree-bindings/tpm2/tis-tpm2-spi.txt | 2 +-
>>>  drivers/tpm/tpm2_tis_spi.c                     | 2 +-
>>>  2 files changed, 2 insertions(+), 2 deletions(-)
>>>
>>> diff --git a/doc/device-tree-bindings/tpm2/tis-tpm2-spi.txt b/doc/device-tree-bindings/tpm2/tis-tpm2-spi.txt
>>> index 3a2ee4bd17..bbcd12950f 100644
>>> --- a/doc/device-tree-bindings/tpm2/tis-tpm2-spi.txt
>>> +++ b/doc/device-tree-bindings/tpm2/tis-tpm2-spi.txt
>>> @@ -6,7 +6,7 @@ Required properties:
>>>  - reg                        : SPI Chip select
>>>
>>>  Optional properties:
>>> -- gpio-reset         : Reset GPIO (if not connected to the SoC reset line)
>>> +- reset-gpios                : Reset GPIO (if not connected to the SoC reset line)
>>>  - spi-max-frequency  : See spi-bus.txt
>>>
>>>  Example:
>>> diff --git a/drivers/tpm/tpm2_tis_spi.c b/drivers/tpm/tpm2_tis_spi.c
>>> index 4b33ac8fd3..94ac52d9ce 100644
>>> --- a/drivers/tpm/tpm2_tis_spi.c
>>> +++ b/drivers/tpm/tpm2_tis_spi.c
>>> @@ -589,7 +589,7 @@ static int tpm_tis_spi_probe(struct udevice *dev)
>>>       if (CONFIG_IS_ENABLED(DM_GPIO)) {
>>>               struct gpio_desc reset_gpio;
>>>
>>> -             ret = gpio_request_by_name(dev, "gpio-reset", 0,
>>> +             ret = gpio_request_by_name(dev, "reset-gpios", 0,
>>>                                          &reset_gpio, GPIOD_IS_OUT);
>>>               if (ret) {
>>>                       log(LOGC_NONE, LOGL_NOTICE, "%s: missing reset GPIO\n",
>>>
>>
>> I think you should deprecate gpio-reset but keep supporting that option
>> with any warning and add code for reset-gpios.
>>
>> Also would be good to add it as optional property to Linux kernel to
>> keep it in sync.
> 
> Hi
> 
> The reason the Linux kernel does not have a TPM reset signal, is
> that being able to reset the chip from software is a vulnerability.
> There was a discussion on it over on the Barebox mailing list
> a while ago.
> 
> TLDR: TPM reset needs to follow SOC reset.

I expect chip has the reset in both cases and it is just about who
should be calling it. But we should be using the same DT for u-boot and
Linux. It means it should be handled properly but described properly.

Thanks,
Michal