Messages in this thread | | | Date | Thu, 16 Jun 2016 22:18:25 +0200 | From | Jarkko Sakkinen <> | Subject | Re: [tpmdd-devel] [PATCH 3/3] tpm, tpm_crb: runtime power management |
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On Thu, Jun 16, 2016 at 09:57:35PM +0200, Jarkko Sakkinen wrote: > Hi Thomas, > > I'm on a vacation this week but I'll give you quick answers :) > > On Tue, Jun 14, 2016 at 04:14:58PM +0300, Tomas Winkler wrote: > > On Wed, Jun 8, 2016 at 2:02 AM, Jarkko Sakkinen > > <jarkko.sakkinen@linux.intel.com> wrote: > > > The register TPM_CRB_CTRL_REQ_0 contains bits goIdle and cmdReady for > > > invoking the chip to suspend and resume. This commit implements runtime > > > PM for tpm_crb by using these bits. > > > > > > The legacy ACPI start (SMI + DMA) based devices do not support these > > > bits. Thus this functionality only is enabled only for CRB start (MMIO) > > > based devices. > > > > > > Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com> > > > --- > > > drivers/char/tpm/tpm-interface.c | 3 ++ > > > drivers/char/tpm/tpm_crb.c | 62 ++++++++++++++++++++++++++++++++++++++-- > > > 2 files changed, 63 insertions(+), 2 deletions(-) > > > > > > diff --git a/drivers/char/tpm/tpm-interface.c b/drivers/char/tpm/tpm-interface.c > > > index 5e3c1b6..3b85648 100644 > > > --- a/drivers/char/tpm/tpm-interface.c > > > +++ b/drivers/char/tpm/tpm-interface.c > > > @@ -29,6 +29,7 @@ > > > #include <linux/mutex.h> > > > #include <linux/spinlock.h> > > > #include <linux/freezer.h> > > > +#include <linux/pm_runtime.h> > > > > > > #include "tpm.h" > > > #include "tpm_eventlog.h" > > > @@ -350,6 +351,7 @@ ssize_t tpm_transmit(struct tpm_chip *chip, const char *buf, > > > return -E2BIG; > > > } > > > > > > + pm_runtime_get_sync(chip->dev.parent); > > > mutex_lock(&chip->tpm_mutex); > > > > > > rc = chip->ops->send(chip, (u8 *) buf, count); > > > @@ -394,6 +396,7 @@ out_recv: > > > "tpm_transmit: tpm_recv: error %zd\n", rc); > > > out: > > > mutex_unlock(&chip->tpm_mutex); > > > + pm_runtime_put_sync(chip->dev.parent); > > > return rc; > > > } > > > > > > diff --git a/drivers/char/tpm/tpm_crb.c b/drivers/char/tpm/tpm_crb.c > > > index ca2cad9..71cc7cd 100644 > > > --- a/drivers/char/tpm/tpm_crb.c > > > +++ b/drivers/char/tpm/tpm_crb.c > > > @@ -20,6 +20,7 @@ > > > #include <linux/rculist.h> > > > #include <linux/module.h> > > > #include <linux/platform_device.h> > > > +#include <linux/pm_runtime.h> > > > #include "tpm.h" > > > > > > #define ACPI_SIG_TPM2 "TPM2" > > > @@ -41,7 +42,6 @@ enum crb_ca_request { > > > > > > enum crb_ca_status { > > > CRB_CA_STS_ERROR = BIT(0), > > > - CRB_CA_STS_TPM_IDLE = BIT(1), > > > }; > > > > > > enum crb_start { > > > @@ -68,6 +68,8 @@ struct crb_control_area { > > > > > > enum crb_status { > > > CRB_STS_COMPLETE = BIT(0), > > > + CRB_STS_READY = BIT(1), > > > + CRB_STS_IDLE = BIT(2), > > > }; > > > > > > enum crb_flags { > > > @@ -81,9 +83,52 @@ struct crb_priv { > > > struct crb_control_area __iomem *cca; > > > u8 __iomem *cmd; > > > u8 __iomem *rsp; > > > + wait_queue_head_t idle_queue; > > > > > > I'm failing to find the code that is calling wake_up_interruptible(idle_queue); > > Ugh, my bad. This actually should not be declared at all. Will remove it > from the next version and NULL should be passed to wait_for_tpm_stat() > as the driver does not yet support interrupts (Haswell did not have > them, not sure about later gens). > > > > > }; > > > > > > -static SIMPLE_DEV_PM_OPS(crb_pm, tpm_pm_suspend, tpm_pm_resume); > > > +static int __maybe_unused crb_runtime_suspend(struct device *dev) > > > +{ > > > + struct tpm_chip *chip = dev_get_drvdata(dev); > > > + struct crb_priv *priv = dev_get_drvdata(&chip->dev); > > > + u32 req; > > > + > > > + if (priv->flags & CRB_FL_ACPI_START) > > > + return 0; > > > + > > > + req = ioread32(&priv->cca->req); > > > + > > > + iowrite32(cpu_to_le32(req | CRB_CA_REQ_GO_IDLE), &priv->cca->req); > > > + > > > + if (wait_for_tpm_stat(chip, CRB_STS_IDLE, chip->timeout_c, > > > + &priv->idle_queue, false)) > > > + dev_warn(&chip->dev, "idle timed out\n"); > > > > Unfortunately you cannot do that as there is an HW errata, the status > > register value might not be defined here during power transition > > You should poll for request CRB_CA_REQ_GO_IDLE goes to 0 as descried > > in the spec . only after that you can check for the status register > > (thought it's maybe not needed) > > And I do exactly what you are asking me to do. > > > > + > > > + return 0; > > > +} > > > + > > > +static int __maybe_unused crb_runtime_resume(struct device *dev) > > > > why this is marked unused, why just not compile it out? if the > > CONFIG_PM is not set? > > It is compiled out if it is unused. Why would you want to trash the code > with #ifdef cages if they are not necessary? I can add /* CONFIG_PM */ > before the function if that makes it cleaner. > > > > +{ > > > + struct tpm_chip *chip = dev_get_drvdata(dev); > > > + struct crb_priv *priv = dev_get_drvdata(&chip->dev); > > > + u32 req; > > > + > > > + if (priv->flags & CRB_FL_ACPI_START) > > > + return 0; > > > + > > > + req = ioread32(&priv->cca->req); > > > + iowrite32(cpu_to_le32(req | CRB_CA_REQ_CMD_READY), &priv->cca->req); > > > + > > > + if (wait_for_tpm_stat(chip, CRB_STS_READY, chip->timeout_c, > > > + &priv->idle_queue, false)) > > > + dev_warn(&chip->dev, "wake timed out\n"); > > > > Same here, you should wait for CRB_CA_REQ_CMD_READ to get cleared, > > only after that it is safe to check the status register. > > It does exactly that. I'm not using CRB status register for anything. > > > > + > > > + return 0; > > > +} > > > + > > > +static const struct dev_pm_ops crb_pm = { > > > + SET_RUNTIME_PM_OPS(crb_runtime_suspend, crb_runtime_resume, NULL) > > > + SET_SYSTEM_SLEEP_PM_OPS(tpm_pm_suspend, tpm_pm_resume) > > > +}; > > > > > > static u8 crb_status(struct tpm_chip *chip) > > > { > > > @@ -94,6 +139,14 @@ static u8 crb_status(struct tpm_chip *chip) > > > CRB_START_INVOKE) > > > sts |= CRB_STS_COMPLETE; > > > > > > + if ((ioread32(&priv->cca->req) & CRB_CA_REQ_CMD_READY) != > > > + CRB_CA_REQ_CMD_READY) > > > + sts |= CRB_STS_READY; > > > > There is meaning for checking this w/o the actual transition i.e. > > setting the before > > I'm not sure what you are trying to say.
... but I can undertand why this looks so confusing to you. Maybe it would be a better idea to completely discard the use of wait_for_tpm_stat() and changes to crb_status() and do instead the following in runtime_suspend/resume (example is for resume):
1. Set REQ_CMD_READY. 2. Sleep for TIMEOUT C. 3. Check the register and return -ETIME if it is not cleared.
I think this patch is abusing wait_for_tpm_stat() and it is not really good fit here. How does this sound?
/Jarkko
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