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

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Date:   Thu, 14 Apr 2022 19:51:55 +0300
From:   Jarkko Sakkinen <jarkko@...nel.org>
To:     Paul Menzel <pmenzel@...gen.mpg.de>
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

On Thu, 2022-04-14 at 17:06 +0200, Paul Menzel wrote:
> 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,

Yeah, I meant Jes :-)

/Jarkko