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path: root/drivers/rtc/rtc-imxdi.c
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Diffstat (limited to 'drivers/rtc/rtc-imxdi.c')
-rw-r--r--drivers/rtc/rtc-imxdi.c623
1 files changed, 623 insertions, 0 deletions
diff --git a/drivers/rtc/rtc-imxdi.c b/drivers/rtc/rtc-imxdi.c
new file mode 100644
index 0000000..8fcaf63
--- /dev/null
+++ b/drivers/rtc/rtc-imxdi.c
@@ -0,0 +1,623 @@
+/*
+ * Copyright 2008-2009 Freescale Semiconductor, Inc. All Rights Reserved.
+ * Copyright 2010 Orex Computed Radiography
+ */
+
+/*
+ * The code contained herein is licensed under the GNU General Public
+ * License. You may obtain a copy of the GNU General Public License
+ * Version 2 or later at the following locations:
+ *
+ * http://www.opensource.org/licenses/gpl-license.html
+ * http://www.gnu.org/copyleft/gpl.html
+ */
+
+/* based on rtc-mc13892.c */
+
+/*
+ * 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 <common.h>
+#include <driver.h>
+#include <init.h>
+#include <rtc.h>
+#include <io.h>
+#include <linux/clk.h>
+#include <linux/rtc.h>
+#include <linux/nvmem-provider.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
+ * @dev: pionter to dev
+ * @rtc: pointer to rtc struct
+ * @ioaddr: IO registers pointer
+ * @clk: input reference clock
+ * @dsr: copy of the DSR register
+ */
+struct imxdi_dev {
+ struct device_d *dev;
+ struct rtc_device rtc;
+ void __iomem *ioaddr;
+ struct clk *clk;
+ u32 dsr;
+ struct nvmem_device *nvmem;
+};
+
+/* 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
+ */
+ udelay(130);
+}
+
+static void di_what_is_to_be_done(struct imxdi_dev *imxdi,
+ const char *power_supply)
+{
+ dev_emerg(imxdi->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->dev, "DSR register reports: %08X\n", 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->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
+ * 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->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->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->dev, "Invalid stated unit detected\n");
+ rc = di_handle_invalid_state(imxdi, dsr);
+ break;
+ case DSR_SVF:
+ dev_warn(imxdi->dev, "Failure stated unit detected\n");
+ rc = di_handle_failure_state(imxdi, dsr);
+ break;
+ case DSR_NVF | DSR_SVF:
+ dev_warn(imxdi->dev,
+ "Failure+Invalid stated unit detected\n");
+ rc = di_handle_invalid_and_failure_state(imxdi, dsr);
+ break;
+ default:
+ dev_notice(imxdi->dev, "Unlocked unit detected\n");
+ rc = di_handle_valid_state(imxdi, dsr);
+ }
+
+ return rc;
+}
+
+/*
+ * 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->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->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 rc = 0;
+ uint32_t dsr;
+ uint64_t start;
+
+ /* do the register write */
+ writel(val, imxdi->ioaddr + reg);
+
+ start = get_time_ns();
+
+ /* wait for the write to finish */
+ while (1) {
+ dsr = readl(imxdi->ioaddr + DSR);
+
+ if (dsr & (DSR_WCF | DSR_WEF))
+ break;
+ if (is_timeout(start, MSECOND))
+ return -EIO;
+ }
+
+ /* check for write error */
+ if (dsr & DSR_WEF) {
+ clear_write_error(imxdi);
+ rc = -EIO;
+ }
+
+ return rc;
+}
+
+static struct imxdi_dev *to_imxdi_dev(struct rtc_device *rtc)
+{
+ return container_of(rtc, struct imxdi_dev, rtc);
+}
+
+/*
+ * read the seconds portion of the current time from the dryice time counter
+ */
+static int dryice_rtc_read_time(struct rtc_device *rtc, struct rtc_time *tm)
+{
+ struct imxdi_dev *imxdi = to_imxdi_dev(rtc);
+ unsigned long now;
+
+ now = readl(imxdi->ioaddr + DTCMR);
+ rtc_time_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 rtc_device *rtc, struct rtc_time *tm)
+{
+ struct imxdi_dev *imxdi = to_imxdi_dev(rtc);
+ u32 dcr, dsr;
+ int ret;
+ unsigned long secs;
+
+ ret = rtc_tm_to_time(tm, &secs);
+ if (ret)
+ return ret;
+
+ 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 */
+ ret = di_write_wait(imxdi, 0, DTCLR);
+ if (ret)
+ return ret;
+
+ ret = di_write_wait(imxdi, secs, DTCMR);
+ if (ret)
+ return ret;
+
+ return di_write_wait(imxdi, readl(imxdi->ioaddr + DCR) | DCR_TCE, DCR);
+}
+
+static const struct rtc_class_ops dryice_rtc_ops = {
+ .read_time = dryice_rtc_read_time,
+ .set_time = dryice_rtc_set_time,
+};
+
+static int nvstore_write(struct device_d *dev, const int reg, const void *val,
+ int bytes)
+{
+ struct imxdi_dev *imxdi = dev->parent->priv;
+ const u32 *val32 = val;
+
+ if (bytes != 4)
+ return 0;
+
+ writel(*val32, imxdi->ioaddr + DGPR);
+
+ return 0;
+}
+
+static int nvstore_read(struct device_d *dev, const int reg, void *val,
+ int bytes)
+{
+ struct imxdi_dev *imxdi = dev->parent->priv;
+ u32 *val32 = val;
+
+ if (bytes != 4)
+ return 0;
+
+ *val32 = readl(imxdi->ioaddr + DGPR);
+
+ return 0;
+}
+
+static struct nvmem_bus nvstore_nvmem_bus = {
+ .write = nvstore_write,
+ .read = nvstore_read,
+};
+
+static struct nvmem_config nvstore_nvmem_config = {
+ .name = "nvstore",
+ .stride = 4,
+ .word_size = 4,
+ .size = 4,
+ .bus = &nvstore_nvmem_bus,
+};
+
+static int __init dryice_rtc_probe(struct device_d *dev)
+{
+ struct resource *res;
+ struct imxdi_dev *imxdi;
+ int ret;
+
+ imxdi = xzalloc(sizeof(*imxdi));
+
+ imxdi->dev = dev;
+ imxdi->rtc.ops = &dryice_rtc_ops;
+
+ res = dev_request_mem_resource(dev, 0);
+ if (IS_ERR(res))
+ return PTR_ERR(res);
+
+ imxdi->ioaddr = IOMEM(res->start);
+
+ imxdi->clk = clk_get(dev, NULL);
+ if (IS_ERR(imxdi->clk))
+ return PTR_ERR(imxdi->clk);
+
+ ret = clk_enable(imxdi->clk);
+ if (ret)
+ return ret;
+
+ /*
+ * Initialize dryice hardware
+ */
+
+ /* mask all interrupts */
+ writel(0, imxdi->ioaddr + DIER);
+
+ ret = di_handle_state(imxdi);
+ if (ret)
+ goto err;
+
+ dev->priv = imxdi;
+
+ nvstore_nvmem_config.dev = dev;
+
+ imxdi->nvmem = nvmem_register(&nvstore_nvmem_config);
+ if (IS_ENABLED(CONFIG_NVMEM) && IS_ERR(imxdi->nvmem)) {
+ ret = PTR_ERR(imxdi->nvmem);
+ goto err;
+ }
+
+ ret = rtc_register(&imxdi->rtc);
+ if (ret)
+ goto err;
+
+ return 0;
+
+err:
+ clk_disable(imxdi->clk);
+
+ return ret;
+}
+
+static __maybe_unused const struct of_device_id dryice_dt_ids[] = {
+ { .compatible = "fsl,imx25-rtc" },
+ { /* sentinel */ }
+};
+
+static struct driver_d dryice_rtc_driver = {
+ .name = "imx-di-rtc",
+ .probe = dryice_rtc_probe,
+ .of_compatible = DRV_OF_COMPAT(dryice_dt_ids),
+};
+device_platform_driver(dryice_rtc_driver);