diff options
Diffstat (limited to '')
| -rw-r--r-- | drivers/rtc/rtc-imxdi.c | 865 |
1 files changed, 865 insertions, 0 deletions
diff --git a/drivers/rtc/rtc-imxdi.c b/drivers/rtc/rtc-imxdi.c new file mode 100644 index 000000000..8d141d8a5 --- /dev/null +++ b/drivers/rtc/rtc-imxdi.c @@ -0,0 +1,865 @@ +// SPDX-License-Identifier: GPL-2.0+ +/* + * Copyright 2008-2009 Freescale Semiconductor, Inc. All Rights Reserved. + * Copyright 2010 Orex Computed Radiography + */ + +/* + * This driver uses the 47-bit 32 kHz counter in the Freescale DryIce block + * to implement a Linux RTC. Times and alarms are truncated to seconds. + * Since the RTC framework performs API locking via rtc->ops_lock the + * only simultaneous accesses we need to deal with is updating DryIce + * registers while servicing an alarm. + * + * Note that reading the DSR (DryIce Status Register) automatically clears + * the WCF (Write Complete Flag). All DryIce writes are synchronized to the + * LP (Low Power) domain and set the WCF upon completion. Writes to the + * DIER (DryIce Interrupt Enable Register) are the only exception. These + * occur at normal bus speeds and do not set WCF. Periodic interrupts are + * not supported by the hardware. + */ + +#include <linux/io.h> +#include <linux/clk.h> +#include <linux/delay.h> +#include <linux/module.h> +#include <linux/platform_device.h> +#include <linux/rtc.h> +#include <linux/sched.h> +#include <linux/spinlock.h> +#include <linux/workqueue.h> +#include <linux/of.h> + +/* DryIce Register Definitions */ + +#define DTCMR 0x00 /* Time Counter MSB Reg */ +#define DTCLR 0x04 /* Time Counter LSB Reg */ + +#define DCAMR 0x08 /* Clock Alarm MSB Reg */ +#define DCALR 0x0c /* Clock Alarm LSB Reg */ +#define DCAMR_UNSET 0xFFFFFFFF /* doomsday - 1 sec */ + +#define DCR 0x10 /* Control Reg */ +#define DCR_TDCHL (1 << 30) /* Tamper-detect configuration hard lock */ +#define DCR_TDCSL (1 << 29) /* Tamper-detect configuration soft lock */ +#define DCR_KSSL (1 << 27) /* Key-select soft lock */ +#define DCR_MCHL (1 << 20) /* Monotonic-counter hard lock */ +#define DCR_MCSL (1 << 19) /* Monotonic-counter soft lock */ +#define DCR_TCHL (1 << 18) /* Timer-counter hard lock */ +#define DCR_TCSL (1 << 17) /* Timer-counter soft lock */ +#define DCR_FSHL (1 << 16) /* Failure state hard lock */ +#define DCR_TCE (1 << 3) /* Time Counter Enable */ +#define DCR_MCE (1 << 2) /* Monotonic Counter Enable */ + +#define DSR 0x14 /* Status Reg */ +#define DSR_WTD (1 << 23) /* Wire-mesh tamper detected */ +#define DSR_ETBD (1 << 22) /* External tamper B detected */ +#define DSR_ETAD (1 << 21) /* External tamper A detected */ +#define DSR_EBD (1 << 20) /* External boot detected */ +#define DSR_SAD (1 << 19) /* SCC alarm detected */ +#define DSR_TTD (1 << 18) /* Temperature tamper detected */ +#define DSR_CTD (1 << 17) /* Clock tamper detected */ +#define DSR_VTD (1 << 16) /* Voltage tamper detected */ +#define DSR_WBF (1 << 10) /* Write Busy Flag (synchronous) */ +#define DSR_WNF (1 << 9) /* Write Next Flag (synchronous) */ +#define DSR_WCF (1 << 8) /* Write Complete Flag (synchronous)*/ +#define DSR_WEF (1 << 7) /* Write Error Flag */ +#define DSR_CAF (1 << 4) /* Clock Alarm Flag */ +#define DSR_MCO (1 << 3) /* monotonic counter overflow */ +#define DSR_TCO (1 << 2) /* time counter overflow */ +#define DSR_NVF (1 << 1) /* Non-Valid Flag */ +#define DSR_SVF (1 << 0) /* Security Violation Flag */ + +#define DIER 0x18 /* Interrupt Enable Reg (synchronous) */ +#define DIER_WNIE (1 << 9) /* Write Next Interrupt Enable */ +#define DIER_WCIE (1 << 8) /* Write Complete Interrupt Enable */ +#define DIER_WEIE (1 << 7) /* Write Error Interrupt Enable */ +#define DIER_CAIE (1 << 4) /* Clock Alarm Interrupt Enable */ +#define DIER_SVIE (1 << 0) /* Security-violation Interrupt Enable */ + +#define DMCR 0x1c /* DryIce Monotonic Counter Reg */ + +#define DTCR 0x28 /* DryIce Tamper Configuration Reg */ +#define DTCR_MOE (1 << 9) /* monotonic overflow enabled */ +#define DTCR_TOE (1 << 8) /* time overflow enabled */ +#define DTCR_WTE (1 << 7) /* wire-mesh tamper enabled */ +#define DTCR_ETBE (1 << 6) /* external B tamper enabled */ +#define DTCR_ETAE (1 << 5) /* external A tamper enabled */ +#define DTCR_EBE (1 << 4) /* external boot tamper enabled */ +#define DTCR_SAIE (1 << 3) /* SCC enabled */ +#define DTCR_TTE (1 << 2) /* temperature tamper enabled */ +#define DTCR_CTE (1 << 1) /* clock tamper enabled */ +#define DTCR_VTE (1 << 0) /* voltage tamper enabled */ + +#define DGPR 0x3c /* DryIce General Purpose Reg */ + +/** + * struct imxdi_dev - private imxdi rtc data + * @pdev: pointer to platform dev + * @rtc: pointer to rtc struct + * @ioaddr: IO registers pointer + * @clk: input reference clock + * @dsr: copy of the DSR register + * @irq_lock: interrupt enable register (DIER) lock + * @write_wait: registers write complete queue + * @write_mutex: serialize registers write + * @work: schedule alarm work + */ +struct imxdi_dev { + struct platform_device *pdev; + struct rtc_device *rtc; + void __iomem *ioaddr; + struct clk *clk; + u32 dsr; + spinlock_t irq_lock; + wait_queue_head_t write_wait; + struct mutex write_mutex; + struct work_struct work; +}; + +/* Some background: + * + * The DryIce unit is a complex security/tamper monitor device. To be able do + * its job in a useful manner it runs a bigger statemachine to bring it into + * security/tamper failure state and once again to bring it out of this state. + * + * This unit can be in one of three states: + * + * - "NON-VALID STATE" + * always after the battery power was removed + * - "FAILURE STATE" + * if one of the enabled security events has happened + * - "VALID STATE" + * if the unit works as expected + * + * Everything stops when the unit enters the failure state including the RTC + * counter (to be able to detect the time the security event happened). + * + * The following events (when enabled) let the DryIce unit enter the failure + * state: + * + * - wire-mesh-tamper detect + * - external tamper B detect + * - external tamper A detect + * - temperature tamper detect + * - clock tamper detect + * - voltage tamper detect + * - RTC counter overflow + * - monotonic counter overflow + * - external boot + * + * If we find the DryIce unit in "FAILURE STATE" and the TDCHL cleared, we + * can only detect this state. In this case the unit is completely locked and + * must force a second "SYSTEM POR" to bring the DryIce into the + * "NON-VALID STATE" + "FAILURE STATE" where a recovery is possible. + * If the TDCHL is set in the "FAILURE STATE" we are out of luck. In this case + * a battery power cycle is required. + * + * In the "NON-VALID STATE" + "FAILURE STATE" we can clear the "FAILURE STATE" + * and recover the DryIce unit. By clearing the "NON-VALID STATE" as the last + * 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 happened 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 + * software 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) +{ + unsigned long flags; + + spin_lock_irqsave(&imxdi->irq_lock, flags); + writel(readl(imxdi->ioaddr + DIER) | intr, + imxdi->ioaddr + DIER); + spin_unlock_irqrestore(&imxdi->irq_lock, flags); +} + +/* + * disable a dryice interrupt + */ +static void di_int_disable(struct imxdi_dev *imxdi, u32 intr) +{ + unsigned long flags; + + spin_lock_irqsave(&imxdi->irq_lock, flags); + writel(readl(imxdi->ioaddr + DIER) & ~intr, + imxdi->ioaddr + DIER); + spin_unlock_irqrestore(&imxdi->irq_lock, flags); +} + +/* + * This function attempts to clear the dryice write-error flag. + * + * A dryice write error is similar to a bus fault and should not occur in + * normal operation. Clearing the flag requires another write, so the root + * cause of the problem may need to be fixed before the flag can be cleared. + */ +static void clear_write_error(struct imxdi_dev *imxdi) +{ + int cnt; + + dev_warn(&imxdi->pdev->dev, "WARNING: Register write error!\n"); + + /* clear the write error flag */ + writel(DSR_WEF, imxdi->ioaddr + DSR); + + /* wait for it to take effect */ + for (cnt = 0; cnt < 1000; cnt++) { + if ((readl(imxdi->ioaddr + DSR) & DSR_WEF) == 0) + return; + udelay(10); + } + dev_err(&imxdi->pdev->dev, + "ERROR: Cannot clear write-error flag!\n"); +} + +/* + * Write a dryice register and wait until it completes. + * + * This function uses interrupts to determine when the + * write has completed. + */ +static int di_write_wait(struct imxdi_dev *imxdi, u32 val, int reg) +{ + int ret; + int rc = 0; + + /* serialize register writes */ + mutex_lock(&imxdi->write_mutex); + + /* enable the write-complete interrupt */ + di_int_enable(imxdi, DIER_WCIE); + + imxdi->dsr = 0; + + /* do the register write */ + writel(val, imxdi->ioaddr + reg); + + /* wait for the write to finish */ + ret = wait_event_interruptible_timeout(imxdi->write_wait, + imxdi->dsr & (DSR_WCF | DSR_WEF), msecs_to_jiffies(1)); + if (ret < 0) { + rc = ret; + goto out; + } else if (ret == 0) { + dev_warn(&imxdi->pdev->dev, + "Write-wait timeout " + "val = 0x%08x reg = 0x%08x\n", val, reg); + } + + /* check for write error */ + if (imxdi->dsr & DSR_WEF) { + clear_write_error(imxdi); + rc = -EIO; + } + +out: + mutex_unlock(&imxdi->write_mutex); + + return rc; +} + +/* + * read the seconds portion of the current time from the dryice time counter + */ +static int dryice_rtc_read_time(struct device *dev, struct rtc_time *tm) +{ + struct imxdi_dev *imxdi = dev_get_drvdata(dev); + unsigned long now; + + now = readl(imxdi->ioaddr + DTCMR); + rtc_time64_to_tm(now, tm); + + return 0; +} + +/* + * set the seconds portion of dryice time counter and clear the + * fractional part. + */ +static int dryice_rtc_set_time(struct device *dev, struct rtc_time *tm) +{ + struct imxdi_dev *imxdi = dev_get_drvdata(dev); + u32 dcr, dsr; + int rc; + + dcr = readl(imxdi->ioaddr + DCR); + dsr = readl(imxdi->ioaddr + DSR); + + if (!(dcr & DCR_TCE) || (dsr & DSR_SVF)) { + if (dcr & DCR_TCHL) { + /* we are even more out of luck */ + di_what_is_to_be_done(imxdi, "battery"); + return -EPERM; + } + if ((dcr & DCR_TCSL) || (dsr & DSR_SVF)) { + /* we are out of luck for now */ + di_what_is_to_be_done(imxdi, "main"); + return -EPERM; + } + } + + /* zero the fractional part first */ + rc = di_write_wait(imxdi, 0, DTCLR); + if (rc != 0) + return rc; + + rc = di_write_wait(imxdi, rtc_tm_to_time64(tm), DTCMR); + if (rc != 0) + return rc; + + return di_write_wait(imxdi, readl(imxdi->ioaddr + DCR) | DCR_TCE, DCR); +} + +static int dryice_rtc_alarm_irq_enable(struct device *dev, + unsigned int enabled) +{ + struct imxdi_dev *imxdi = dev_get_drvdata(dev); + + if (enabled) + di_int_enable(imxdi, DIER_CAIE); + else + di_int_disable(imxdi, DIER_CAIE); + + return 0; +} + +/* + * read the seconds portion of the alarm register. + * the fractional part of the alarm register is always zero. + */ +static int dryice_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alarm) +{ + struct imxdi_dev *imxdi = dev_get_drvdata(dev); + u32 dcamr; + + dcamr = readl(imxdi->ioaddr + DCAMR); + rtc_time64_to_tm(dcamr, &alarm->time); + + /* alarm is enabled if the interrupt is enabled */ + alarm->enabled = (readl(imxdi->ioaddr + DIER) & DIER_CAIE) != 0; + + /* don't allow the DSR read to mess up DSR_WCF */ + mutex_lock(&imxdi->write_mutex); + + /* alarm is pending if the alarm flag is set */ + alarm->pending = (readl(imxdi->ioaddr + DSR) & DSR_CAF) != 0; + + mutex_unlock(&imxdi->write_mutex); + + return 0; +} + +/* + * set the seconds portion of dryice alarm register + */ +static int dryice_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alarm) +{ + struct imxdi_dev *imxdi = dev_get_drvdata(dev); + int rc; + + /* write the new alarm time */ + rc = di_write_wait(imxdi, rtc_tm_to_time64(&alarm->time), DCAMR); + if (rc) + return rc; + + if (alarm->enabled) + di_int_enable(imxdi, DIER_CAIE); /* enable alarm intr */ + else + di_int_disable(imxdi, DIER_CAIE); /* disable alarm intr */ + + return 0; +} + +static const struct rtc_class_ops dryice_rtc_ops = { + .read_time = dryice_rtc_read_time, + .set_time = dryice_rtc_set_time, + .alarm_irq_enable = dryice_rtc_alarm_irq_enable, + .read_alarm = dryice_rtc_read_alarm, + .set_alarm = dryice_rtc_set_alarm, +}; + +/* + * interrupt handler for dryice "normal" and security violation interrupt + */ +static irqreturn_t dryice_irq(int irq, void *dev_id) +{ + struct imxdi_dev *imxdi = dev_id; + u32 dsr, dier; + irqreturn_t rc = IRQ_NONE; + + dier = readl(imxdi->ioaddr + DIER); + dsr = readl(imxdi->ioaddr + DSR); + + /* handle the security violation event */ + if (dier & DIER_SVIE) { + if (dsr & DSR_SVF) { + /* + * Disable the interrupt when this kind of event has + * happened. + * There cannot be more than one event of this type, + * because it needs a complex state change + * including a main power cycle to get again out of + * this state. + */ + di_int_disable(imxdi, DIER_SVIE); + /* report the violation */ + di_report_tamper_info(imxdi, dsr); + rc = IRQ_HANDLED; + } + } + + /* handle write complete and write error cases */ + if (dier & DIER_WCIE) { + /*If the write wait queue is empty then there is no pending + operations. It means the interrupt is for DryIce -Security. + IRQ must be returned as none.*/ + if (list_empty_careful(&imxdi->write_wait.head)) + return rc; + + /* DSR_WCF clears itself on DSR read */ + if (dsr & (DSR_WCF | DSR_WEF)) { + /* mask the interrupt */ + di_int_disable(imxdi, DIER_WCIE); + + /* save the dsr value for the wait queue */ + imxdi->dsr |= dsr; + + wake_up_interruptible(&imxdi->write_wait); + rc = IRQ_HANDLED; + } + } + + /* handle the alarm case */ + if (dier & DIER_CAIE) { + /* DSR_WCF clears itself on DSR read */ + if (dsr & DSR_CAF) { + /* mask the interrupt */ + di_int_disable(imxdi, DIER_CAIE); + + /* finish alarm in user context */ + schedule_work(&imxdi->work); + rc = IRQ_HANDLED; + } + } + return rc; +} + +/* + * post the alarm event from user context so it can sleep + * on the write completion. + */ +static void dryice_work(struct work_struct *work) +{ + struct imxdi_dev *imxdi = container_of(work, + struct imxdi_dev, work); + + /* dismiss the interrupt (ignore error) */ + di_write_wait(imxdi, DSR_CAF, DSR); + + /* pass the alarm event to the rtc framework. */ + rtc_update_irq(imxdi->rtc, 1, RTC_AF | RTC_IRQF); +} + +/* + * probe for dryice rtc device + */ +static int __init dryice_rtc_probe(struct platform_device *pdev) +{ + struct imxdi_dev *imxdi; + int norm_irq, sec_irq; + int rc; + + imxdi = devm_kzalloc(&pdev->dev, sizeof(*imxdi), GFP_KERNEL); + if (!imxdi) + return -ENOMEM; + + imxdi->pdev = pdev; + + imxdi->ioaddr = devm_platform_ioremap_resource(pdev, 0); + if (IS_ERR(imxdi->ioaddr)) + return PTR_ERR(imxdi->ioaddr); + + spin_lock_init(&imxdi->irq_lock); + + norm_irq = platform_get_irq(pdev, 0); + if (norm_irq < 0) + return norm_irq; + + /* the 2nd irq is the security violation irq + * make this optional, don't break the device tree ABI + */ + sec_irq = platform_get_irq(pdev, 1); + if (sec_irq <= 0) + sec_irq = IRQ_NOTCONNECTED; + + init_waitqueue_head(&imxdi->write_wait); + + INIT_WORK(&imxdi->work, dryice_work); + + mutex_init(&imxdi->write_mutex); + + imxdi->rtc = devm_rtc_allocate_device(&pdev->dev); + if (IS_ERR(imxdi->rtc)) + return PTR_ERR(imxdi->rtc); + + imxdi->clk = devm_clk_get(&pdev->dev, NULL); + if (IS_ERR(imxdi->clk)) + return PTR_ERR(imxdi->clk); + rc = clk_prepare_enable(imxdi->clk); + if (rc) + return rc; + + /* + * Initialize dryice hardware + */ + + /* mask all interrupts */ + writel(0, imxdi->ioaddr + DIER); + + rc = di_handle_state(imxdi); + if (rc != 0) + goto err; + + rc = devm_request_irq(&pdev->dev, norm_irq, dryice_irq, + IRQF_SHARED, pdev->name, imxdi); + if (rc) { + dev_warn(&pdev->dev, "interrupt not available.\n"); + goto err; + } + + rc = devm_request_irq(&pdev->dev, sec_irq, dryice_irq, + IRQF_SHARED, pdev->name, imxdi); + if (rc) { + dev_warn(&pdev->dev, "security violation interrupt not available.\n"); + /* this is not an error, see above */ + } + + platform_set_drvdata(pdev, imxdi); + + imxdi->rtc->ops = &dryice_rtc_ops; + imxdi->rtc->range_max = U32_MAX; + + rc = rtc_register_device(imxdi->rtc); + if (rc) + goto err; + + return 0; + +err: + clk_disable_unprepare(imxdi->clk); + + return rc; +} + +static int __exit dryice_rtc_remove(struct platform_device *pdev) +{ + struct imxdi_dev *imxdi = platform_get_drvdata(pdev); + + flush_work(&imxdi->work); + + /* mask all interrupts */ + writel(0, imxdi->ioaddr + DIER); + + clk_disable_unprepare(imxdi->clk); + + return 0; +} + +#ifdef CONFIG_OF +static const struct of_device_id dryice_dt_ids[] = { + { .compatible = "fsl,imx25-rtc" }, + { /* sentinel */ } +}; + +MODULE_DEVICE_TABLE(of, dryice_dt_ids); +#endif + +static struct platform_driver dryice_rtc_driver = { + .driver = { + .name = "imxdi_rtc", + .of_match_table = of_match_ptr(dryice_dt_ids), + }, + .remove = __exit_p(dryice_rtc_remove), +}; + +module_platform_driver_probe(dryice_rtc_driver, dryice_rtc_probe); + +MODULE_AUTHOR("Freescale Semiconductor, Inc."); +MODULE_AUTHOR("Baruch Siach <baruch@tkos.co.il>"); +MODULE_DESCRIPTION("IMX DryIce Realtime Clock Driver (RTC)"); +MODULE_LICENSE("GPL"); |