linux-kernel - Re: [PATCH] tpm: cr50: Add new device/vendor ID 0x504a6666

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Message-ID: <068becdf-2d88-65a1-5977-1fedd34a8f0b@molgen.mpg.de>
Date:   Thu, 14 Apr 2022 17:06:24 +0200
From:   Paul Menzel <pmenzel@...gen.mpg.de>
To:     Jarkko Sakkinen <jarkko@...nel.org>
Cc:     "Jes B. Klinke" <jbk@...omium.org>,
        linux-integrity@...r.kernel.org, Jason Gunthorpe <jgg@...pe.ca>,
        Peter Huewe <peterhuewe@....de>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] tpm: cr50: Add new device/vendor ID 0x504a6666

Dear Jarkko,


Am 14.04.22 um 14:08 schrieb Jarkko Sakkinen:
> On Thu, Apr 07, 2022 at 12:21:44PM +0200, Paul Menzel wrote:

>> Thank you for your patch.
>>
>> Am 05.04.22 um 19:37 schrieb Jes B. Klinke:
>>> Accept one additional numerical value of DID:VID for next generation
>>> Google TPM, to be used in future Chromebooks.
>>
>> Maybe extend:
>>
>> … Google TPM with new firmware …
>>
>> The TPM with the new firmware has the code name TI50, and going to use the
>> same interfaces.
>>
>>> This patch touches more lines than may seem necessary, as a result of
>>> the need to move the error case to sit after the two recognized cases.
>>>
>>> Signed-off-by: Jes B. Klinke <jbk@...omium.org>
>>> ---
>>>
>>>    drivers/char/tpm/tpm_tis_i2c_cr50.c | 21 +++++++++++++--------
>>>    1 file changed, 13 insertions(+), 8 deletions(-)
>>>
>>> diff --git a/drivers/char/tpm/tpm_tis_i2c_cr50.c b/drivers/char/tpm/tpm_tis_i2c_cr50.c
>>> index f6c0affbb4567..bf54ebd6724b0 100644
>>> --- a/drivers/char/tpm/tpm_tis_i2c_cr50.c
>>> +++ b/drivers/char/tpm/tpm_tis_i2c_cr50.c
>>> @@ -31,6 +31,7 @@
>>>    #define TPM_CR50_TIMEOUT_SHORT_MS	2		/* Short timeout during transactions */
>>>    #define TPM_CR50_TIMEOUT_NOIRQ_MS	20		/* Timeout for TPM ready without IRQ */
>>>    #define TPM_CR50_I2C_DID_VID		0x00281ae0L	/* Device and vendor ID reg value */
>>> +#define TPM_TI50_I2C_DID_VID		0x504a6666L	/* Device and vendor ID reg value */
>>>    #define TPM_CR50_I2C_MAX_RETRIES	3		/* Max retries due to I2C errors */
>>>    #define TPM_CR50_I2C_RETRY_DELAY_LO	55		/* Min usecs between retries on I2C */
>>>    #define TPM_CR50_I2C_RETRY_DELAY_HI	65		/* Max usecs between retries on I2C */
>>> @@ -742,16 +743,20 @@ static int tpm_cr50_i2c_probe(struct i2c_client *client)
>>>    	}
>>>    	vendor = le32_to_cpup((__le32 *)buf);
>>> -	if (vendor != TPM_CR50_I2C_DID_VID) {
>>> -		dev_err(dev, "Vendor ID did not match! ID was %08x\n", vendor);
>>> -		tpm_cr50_release_locality(chip, true);
>>> -		return -ENODEV;
>>> +	if (vendor == TPM_CR50_I2C_DID_VID) {
>>> +		dev_info(dev, "cr50 TPM 2.0 (i2c 0x%02x irq %d id 0x%x)\n",
>>> +			 client->addr, client->irq, vendor >> 16);
>>> +		return tpm_chip_register(chip);
>>> +	}
>>> +	if (vendor == TPM_TI50_I2C_DID_VID) {
>>> +		dev_info(dev, "ti50 TPM 2.0 (i2c 0x%02x irq %d id 0x%x)\n",
>>> +			 client->addr, client->irq, vendor >> 16);
>>> +		return tpm_chip_register(chip);
>>>    	}
>>
>> Both branches are quite similar. Can a ternary operator be used?
>>
>>      dev_info(dev, "%s TPM 2.0 (i2c 0x%02x irq %d id 0x%x)\n",
>>      	 (vendor == TPM_CR50_I2C_DID_VID) ? "cr50" : "ti50", client->addr,
>> client->irq, vendor >> 16);
>>      return tpm_chip_register(chip);
>>
>> and the original flow be left? (A separate variable can also be added.)
>>
>>> -	dev_info(dev, "cr50 TPM 2.0 (i2c 0x%02x irq %d id 0x%x)\n",
>>> -		 client->addr, client->irq, vendor >> 16);
>>> -
>>> -	return tpm_chip_register(chip);
>>> +	dev_err(dev, "Vendor ID did not match! ID was %08x\n", vendor);
>>> +	tpm_cr50_release_locality(chip, true);
>>> +	return -ENODEV;
>>>    }
>>>    /**

> OK, these are legit suggestions. Paul, can you do these changes and add my
> reviewed-by for the +1 version?

I guess you mean Jes?


Kind regards,

Paul