[PATCH] drivers: tpm2: update reset gpio semantics

[Jorge Ramirez-Ortiz, Foundries]

On 31/05/21, Michal Simek wrote:
> 
> 
> 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.

right, I agree that it should be described properly (that was the
patch intent).

but do we need to keep the legacy property?

> 
> Thanks,
> Michal
> 
>