Commit c7e9bbe0 authored by Juergen Borleis's avatar Juergen Borleis Committed by Alexandre Belloni

rtc: imxdi: add the unit recovery code

This code is required to recover the unit from a security violation.
Hopefully this code can recover the unit from a hardware related invalid
state as well.
Signed-off-by: default avatarJuergen Borleis <jbe@pengutronix.de>
Signed-off-by: default avatarRobert Schwebel <rsc@pengutronix.de>
[rsc: got NDA clearance from Freescale]
Signed-off-by: default avatarAlexandre Belloni <alexandre.belloni@free-electrons.com>
parent 3ba3fab7
......@@ -172,6 +172,281 @@ struct imxdi_dev {
* task, we bring back this unit into life.
*/
/*
* Do a write into the unit without interrupt support.
* We do not need to check the WEF here, because the only reason this kind of
* write error can happen is if we write to the unit twice within the 122 us
* interval. This cannot happen, since we are using this function only while
* setting up the unit.
*/
static void di_write_busy_wait(const struct imxdi_dev *imxdi, u32 val,
unsigned reg)
{
/* do the register write */
writel(val, imxdi->ioaddr + reg);
/*
* now it takes four 32,768 kHz clock cycles to take
* the change into effect = 122 us
*/
usleep_range(130, 200);
}
static void di_report_tamper_info(struct imxdi_dev *imxdi, u32 dsr)
{
u32 dtcr;
dtcr = readl(imxdi->ioaddr + DTCR);
dev_emerg(&imxdi->pdev->dev, "DryIce tamper event detected\n");
/* the following flags force a transition into the "FAILURE STATE" */
if (dsr & DSR_VTD)
dev_emerg(&imxdi->pdev->dev, "%sVoltage Tamper Event\n",
dtcr & DTCR_VTE ? "" : "Spurious ");
if (dsr & DSR_CTD)
dev_emerg(&imxdi->pdev->dev, "%s32768 Hz Clock Tamper Event\n",
dtcr & DTCR_CTE ? "" : "Spurious ");
if (dsr & DSR_TTD)
dev_emerg(&imxdi->pdev->dev, "%sTemperature Tamper Event\n",
dtcr & DTCR_TTE ? "" : "Spurious ");
if (dsr & DSR_SAD)
dev_emerg(&imxdi->pdev->dev,
"%sSecure Controller Alarm Event\n",
dtcr & DTCR_SAIE ? "" : "Spurious ");
if (dsr & DSR_EBD)
dev_emerg(&imxdi->pdev->dev, "%sExternal Boot Tamper Event\n",
dtcr & DTCR_EBE ? "" : "Spurious ");
if (dsr & DSR_ETAD)
dev_emerg(&imxdi->pdev->dev, "%sExternal Tamper A Event\n",
dtcr & DTCR_ETAE ? "" : "Spurious ");
if (dsr & DSR_ETBD)
dev_emerg(&imxdi->pdev->dev, "%sExternal Tamper B Event\n",
dtcr & DTCR_ETBE ? "" : "Spurious ");
if (dsr & DSR_WTD)
dev_emerg(&imxdi->pdev->dev, "%sWire-mesh Tamper Event\n",
dtcr & DTCR_WTE ? "" : "Spurious ");
if (dsr & DSR_MCO)
dev_emerg(&imxdi->pdev->dev,
"%sMonotonic-counter Overflow Event\n",
dtcr & DTCR_MOE ? "" : "Spurious ");
if (dsr & DSR_TCO)
dev_emerg(&imxdi->pdev->dev, "%sTimer-counter Overflow Event\n",
dtcr & DTCR_TOE ? "" : "Spurious ");
}
static void di_what_is_to_be_done(struct imxdi_dev *imxdi,
const char *power_supply)
{
dev_emerg(&imxdi->pdev->dev, "Please cycle the %s power supply in order to get the DryIce/RTC unit working again\n",
power_supply);
}
static int di_handle_failure_state(struct imxdi_dev *imxdi, u32 dsr)
{
u32 dcr;
dev_dbg(&imxdi->pdev->dev, "DSR register reports: %08X\n", dsr);
/* report the cause */
di_report_tamper_info(imxdi, dsr);
dcr = readl(imxdi->ioaddr + DCR);
if (dcr & DCR_FSHL) {
/* we are out of luck */
di_what_is_to_be_done(imxdi, "battery");
return -ENODEV;
}
/*
* with the next SYSTEM POR we will transit from the "FAILURE STATE"
* into the "NON-VALID STATE" + "FAILURE STATE"
*/
di_what_is_to_be_done(imxdi, "main");
return -ENODEV;
}
static int di_handle_valid_state(struct imxdi_dev *imxdi, u32 dsr)
{
/* initialize alarm */
di_write_busy_wait(imxdi, DCAMR_UNSET, DCAMR);
di_write_busy_wait(imxdi, 0, DCALR);
/* clear alarm flag */
if (dsr & DSR_CAF)
di_write_busy_wait(imxdi, DSR_CAF, DSR);
return 0;
}
static int di_handle_invalid_state(struct imxdi_dev *imxdi, u32 dsr)
{
u32 dcr, sec;
/*
* lets disable all sources which can force the DryIce unit into
* the "FAILURE STATE" for now
*/
di_write_busy_wait(imxdi, 0x00000000, DTCR);
/* and lets protect them at runtime from any change */
di_write_busy_wait(imxdi, DCR_TDCSL, DCR);
sec = readl(imxdi->ioaddr + DTCMR);
if (sec != 0)
dev_warn(&imxdi->pdev->dev,
"The security violation has happend at %u seconds\n",
sec);
/*
* the timer cannot be set/modified if
* - the TCHL or TCSL bit is set in DCR
*/
dcr = readl(imxdi->ioaddr + DCR);
if (!(dcr & DCR_TCE)) {
if (dcr & DCR_TCHL) {
/* we are out of luck */
di_what_is_to_be_done(imxdi, "battery");
return -ENODEV;
}
if (dcr & DCR_TCSL) {
di_what_is_to_be_done(imxdi, "main");
return -ENODEV;
}
}
/*
* - the timer counter stops/is stopped if
* - its overflow flag is set (TCO in DSR)
* -> clear overflow bit to make it count again
* - NVF is set in DSR
* -> clear non-valid bit to make it count again
* - its TCE (DCR) is cleared
* -> set TCE to make it count
* - it was never set before
* -> write a time into it (required again if the NVF was set)
*/
/* state handled */
di_write_busy_wait(imxdi, DSR_NVF, DSR);
/* clear overflow flag */
di_write_busy_wait(imxdi, DSR_TCO, DSR);
/* enable the counter */
di_write_busy_wait(imxdi, dcr | DCR_TCE, DCR);
/* set and trigger it to make it count */
di_write_busy_wait(imxdi, sec, DTCMR);
/* now prepare for the valid state */
return di_handle_valid_state(imxdi, __raw_readl(imxdi->ioaddr + DSR));
}
static int di_handle_invalid_and_failure_state(struct imxdi_dev *imxdi, u32 dsr)
{
u32 dcr;
/*
* now we must first remove the tamper sources in order to get the
* device out of the "FAILURE STATE"
* To disable any of the following sources we need to modify the DTCR
*/
if (dsr & (DSR_WTD | DSR_ETBD | DSR_ETAD | DSR_EBD | DSR_SAD |
DSR_TTD | DSR_CTD | DSR_VTD | DSR_MCO | DSR_TCO)) {
dcr = __raw_readl(imxdi->ioaddr + DCR);
if (dcr & DCR_TDCHL) {
/*
* the tamper register is locked. We cannot disable the
* tamper detection. The TDCHL can only be reset by a
* DRYICE POR, but we cannot force a DRYICE POR in
* softwere because we are still in "FAILURE STATE".
* We need a DRYICE POR via battery power cycling....
*/
/*
* out of luck!
* we cannot disable them without a DRYICE POR
*/
di_what_is_to_be_done(imxdi, "battery");
return -ENODEV;
}
if (dcr & DCR_TDCSL) {
/* a soft lock can be removed by a SYSTEM POR */
di_what_is_to_be_done(imxdi, "main");
return -ENODEV;
}
}
/* disable all sources */
di_write_busy_wait(imxdi, 0x00000000, DTCR);
/* clear the status bits now */
di_write_busy_wait(imxdi, dsr & (DSR_WTD | DSR_ETBD | DSR_ETAD |
DSR_EBD | DSR_SAD | DSR_TTD | DSR_CTD | DSR_VTD |
DSR_MCO | DSR_TCO), DSR);
dsr = readl(imxdi->ioaddr + DSR);
if ((dsr & ~(DSR_NVF | DSR_SVF | DSR_WBF | DSR_WNF |
DSR_WCF | DSR_WEF)) != 0)
dev_warn(&imxdi->pdev->dev,
"There are still some sources of pain in DSR: %08x!\n",
dsr & ~(DSR_NVF | DSR_SVF | DSR_WBF | DSR_WNF |
DSR_WCF | DSR_WEF));
/*
* now we are trying to clear the "Security-violation flag" to
* get the DryIce out of this state
*/
di_write_busy_wait(imxdi, DSR_SVF, DSR);
/* success? */
dsr = readl(imxdi->ioaddr + DSR);
if (dsr & DSR_SVF) {
dev_crit(&imxdi->pdev->dev,
"Cannot clear the security violation flag. We are ending up in an endless loop!\n");
/* last resort */
di_what_is_to_be_done(imxdi, "battery");
return -ENODEV;
}
/*
* now we have left the "FAILURE STATE" and ending up in the
* "NON-VALID STATE" time to recover everything
*/
return di_handle_invalid_state(imxdi, dsr);
}
static int di_handle_state(struct imxdi_dev *imxdi)
{
int rc;
u32 dsr;
dsr = readl(imxdi->ioaddr + DSR);
switch (dsr & (DSR_NVF | DSR_SVF)) {
case DSR_NVF:
dev_warn(&imxdi->pdev->dev, "Invalid stated unit detected\n");
rc = di_handle_invalid_state(imxdi, dsr);
break;
case DSR_SVF:
dev_warn(&imxdi->pdev->dev, "Failure stated unit detected\n");
rc = di_handle_failure_state(imxdi, dsr);
break;
case DSR_NVF | DSR_SVF:
dev_warn(&imxdi->pdev->dev,
"Failure+Invalid stated unit detected\n");
rc = di_handle_invalid_and_failure_state(imxdi, dsr);
break;
default:
dev_notice(&imxdi->pdev->dev, "Unlocked unit detected\n");
rc = di_handle_valid_state(imxdi, dsr);
}
return rc;
}
/*
* enable a dryice interrupt
*/
......@@ -491,6 +766,10 @@ static int __init dryice_rtc_probe(struct platform_device *pdev)
/* mask all interrupts */
writel(0, imxdi->ioaddr + DIER);
rc = di_handle_state(imxdi);
if (rc != 0)
goto err;
rc = devm_request_irq(&pdev->dev, imxdi->irq, dryice_norm_irq,
IRQF_SHARED, pdev->name, imxdi);
if (rc) {
......@@ -498,44 +777,6 @@ static int __init dryice_rtc_probe(struct platform_device *pdev)
goto err;
}
/* put dryice into valid state */
if (readl(imxdi->ioaddr + DSR) & DSR_NVF) {
rc = di_write_wait(imxdi, DSR_NVF | DSR_SVF, DSR);
if (rc)
goto err;
}
/* initialize alarm */
rc = di_write_wait(imxdi, DCAMR_UNSET, DCAMR);
if (rc)
goto err;
rc = di_write_wait(imxdi, 0, DCALR);
if (rc)
goto err;
/* clear alarm flag */
if (readl(imxdi->ioaddr + DSR) & DSR_CAF) {
rc = di_write_wait(imxdi, DSR_CAF, DSR);
if (rc)
goto err;
}
/* the timer won't count if it has never been written to */
if (readl(imxdi->ioaddr + DTCMR) == 0) {
rc = di_write_wait(imxdi, 0, DTCMR);
if (rc)
goto err;
}
/* start keeping time */
if (!(readl(imxdi->ioaddr + DCR) & DCR_TCE)) {
rc = di_write_wait(imxdi,
readl(imxdi->ioaddr + DCR) | DCR_TCE,
DCR);
if (rc)
goto err;
}
platform_set_drvdata(pdev, imxdi);
imxdi->rtc = devm_rtc_device_register(&pdev->dev, pdev->name,
&dryice_rtc_ops, THIS_MODULE);
......
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