On Wed, Mar 27, 2024 at 7:44 AM Ilias Apalodimas ilias.apalodimas@linaro.org wrote:
Hi Tim,
On Thu, 21 Mar 2024 at 20:02, Tim Harvey tharvey@gateworks.com wrote:
Instead of displaying what looks like an error message if a gpio-reset dt prop is missing for a TPM dipslay a more informative message about resetting the TPM if the gpio is found:
before: tpm_tis_spi_probe: missing reset GPIO
after: tpm@0: performing 1ms reset on gpio@30210000:12
Note that the reset dt binding prop used in this driver is not dt-compliant; it does not exist in the Linux dt-bindings documentation and the reset is not done by the Linux driver.
Probably for a good reason. You aren't supposed to be able to reset a TPM without resetting the CPUI as well no?
Hi Ilias,
Could you clarify what you know about TPM reset? We use the ATTPM20P [1] which states in the datasheet under the reset pin: "To be compliant with TCG requirements, this pin needs to be tied to system reset. TPM_Init is indicated by asserting this pin."
Our boards have a resistor loading option which routes the TPM RST# to an SoC GPIO or alternately to a POR# (hardware power on reset provided by power supply and/or PMIC). Could you point me to where in the spec it explains what the TPM reset should be connected to?
That being said, printing that the TPM was reset is pointless imho. OTOH the existing error message at least points out a potential problem in the DT.
I'm not sure if you are NAK'ing this patch or asking me to change it.
Displaying a 'missing GPIO' message is not helpful when there is no GPIO in the dt bindings to begin with.
Best Regards,
Tim [1] https://ww1.microchip.com/downloads/en/DeviceDoc/ATTPM20P-Trusted-Platform-M...
Thanks /Ilias
Signed-off-by: Tim Harvey tharvey@gateworks.com
drivers/tpm/tpm2_tis_spi.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-)
diff --git a/drivers/tpm/tpm2_tis_spi.c b/drivers/tpm/tpm2_tis_spi.c index de9cf8f21e07..944540f7a711 100644 --- a/drivers/tpm/tpm2_tis_spi.c +++ b/drivers/tpm/tpm2_tis_spi.c @@ -237,14 +237,14 @@ static int tpm_tis_spi_probe(struct udevice *dev) /* legacy reset */ ret = gpio_request_by_name(dev, "gpio-reset", 0, &reset_gpio, GPIOD_IS_OUT);
if (ret) {log(LOGC_NONE, LOGL_NOTICE,"%s: missing reset GPIO\n", __func__);
if (ret) goto init;
} log(LOGC_NONE, LOGL_NOTICE, "%s: gpio-reset is deprecated\n", __func__); }
log(LOGC_NONE, LOGL_NOTICE,"%s: performing 1ms reset on %s:%d\n", dev->name,reset_gpio.dev->name, reset_gpio.offset); dm_gpio_set_value(&reset_gpio, 1); mdelay(1); dm_gpio_set_value(&reset_gpio, 0);-- 2.25.1