diff options
author | Juergen Borleis <jbe@pengutronix.de> | 2015-04-27 16:59:49 +0300 |
---|---|---|
committer | Alexandre Belloni <alexandre.belloni@free-electrons.com> | 2015-06-19 21:03:21 +0300 |
commit | c7e9bbe022c7bee57d9e14b42a7c3732da8db558 (patch) | |
tree | 7b81b55261e6ef1212646f6657262d2e762f7596 | |
parent | 3ba3fab765beecd599d8e8e00dc2ed4306518dfd (diff) | |
download | linux-c7e9bbe022c7bee57d9e14b42a7c3732da8db558.tar.xz |
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: Juergen Borleis <jbe@pengutronix.de>
Signed-off-by: Robert Schwebel <rsc@pengutronix.de>
[rsc: got NDA clearance from Freescale]
Signed-off-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>
-rw-r--r-- | drivers/rtc/rtc-imxdi.c | 317 |
1 files changed, 279 insertions, 38 deletions
diff --git a/drivers/rtc/rtc-imxdi.c b/drivers/rtc/rtc-imxdi.c index 63ca52b2029b..3d7f0390170e 100644 --- a/drivers/rtc/rtc-imxdi.c +++ b/drivers/rtc/rtc-imxdi.c @@ -173,6 +173,281 @@ struct imxdi_dev { */ /* + * 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 */ static void di_int_enable(struct imxdi_dev *imxdi, u32 intr) @@ -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); |