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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.c580
1 files changed, 580 insertions, 0 deletions
diff --git a/drivers/rtc/rtc-imxdi.c b/drivers/rtc/rtc-imxdi.c
new file mode 100644
index 000000000000..b54fb638c840
--- /dev/null
+++ b/drivers/rtc/rtc-imxdi.c
@@ -0,0 +1,580 @@
+/*
+ * Copyright 2008-2009 Freescale Semiconductor, Inc. All Rights Reserved.
+ */
+
+/*
+ * 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.
+ */
+
+/* #define DEBUG */
+/* #define DI_DEBUG_REGIO */
+
+#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/workqueue.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_TCE (1 << 3) /* Time Counter Enable */
+
+#define DSR 0x14 /* Status Reg */
+#define DSR_WBF (1 << 10) /* Write Busy Flag */
+#define DSR_WNF (1 << 9) /* Write Next Flag */
+#define DSR_WCF (1 << 8) /* Write Complete Flag */
+#define DSR_WEF (1 << 7) /* Write Error Flag */
+#define DSR_CAF (1 << 4) /* Clock Alarm Flag */
+#define DSR_NVF (1 << 1) /* Non-Valid Flag */
+#define DSR_SVF (1 << 0) /* Security Violation Flag */
+
+#define DIER 0x18 /* Interrupt Enable Reg */
+#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 */
+
+#ifndef DI_DEBUG_REGIO
+/* dryice read register */
+#define di_read(pdata, reg) __raw_readl((pdata)->ioaddr + (reg))
+
+/* dryice write register */
+#define di_write(pdata, val, reg) __raw_writel((val), (pdata)->ioaddr + (reg))
+#else
+/* dryice read register - debug version */
+static inline u32 di_read(struct rtc_drv_data *pdata, int reg)
+{
+ u32 val = __raw_readl(pdata->ioaddr + reg);
+ pr_info("di_read(0x%02x) = 0x%08x\n", reg, val);
+ return val;
+}
+
+/* dryice write register - debug version */
+static inline void di_write(struct rtc_drv_data *pdata, u32 val, int reg)
+{
+ printk(KERN_INFO "di_write(0x%08x, 0x%02x)\n", val, reg);
+ __raw_writel(val, pdata->ioaddr + reg);
+}
+#endif
+
+/*
+ * dryice write register with wait and error handling.
+ * all registers, except for DIER, should use this method.
+ */
+#define di_write_wait_err(pdata, val, reg, rc, label) \
+ do { \
+ if (di_write_wait((pdata), (val), (reg))) { \
+ rc = -EIO; \
+ goto label; \
+ } \
+ } while (0)
+
+struct rtc_drv_data {
+ struct platform_device *pdev; /* pointer to platform dev */
+ struct rtc_device *rtc; /* pointer to rtc struct */
+ unsigned long baseaddr; /* physical bass address */
+ void __iomem *ioaddr; /* virtual base address */
+ int size; /* size of register region */
+ int irq; /* dryice normal irq */
+ struct clk *clk; /* dryice clock control */
+ u32 dsr; /* copy of dsr reg from isr */
+ spinlock_t irq_lock; /* irq resource lock */
+ wait_queue_head_t write_wait; /* write-complete queue */
+ struct mutex write_mutex; /* force reg writes to be sequential */
+ struct work_struct work; /* schedule alarm work */
+};
+
+/*
+ * enable a dryice interrupt
+ */
+static inline void di_int_enable(struct rtc_drv_data *pdata, u32 intr)
+{
+ unsigned long flags;
+
+ spin_lock_irqsave(&pdata->irq_lock, flags);
+ di_write(pdata, di_read(pdata, DIER) | intr, DIER);
+ spin_unlock_irqrestore(&pdata->irq_lock, flags);
+}
+
+/*
+ * disable a dryice interrupt
+ */
+static inline void di_int_disable(struct rtc_drv_data *pdata, u32 intr)
+{
+ unsigned long flags;
+
+ spin_lock_irqsave(&pdata->irq_lock, flags);
+ di_write(pdata, di_read(pdata, DIER) & ~intr, DIER);
+ spin_unlock_irqrestore(&pdata->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 rtc_drv_data *pdata)
+{
+ int cnt;
+
+ dev_warn(&pdata->pdev->dev, "WARNING: Register write error!\n");
+
+ for (;;) {
+ /* clear the write error flag */
+ di_write(pdata, DSR_WEF, DSR);
+
+ /* wait for it to take effect */
+ for (cnt = 0; cnt < 100; cnt++) {
+ if ((di_read(pdata, DSR) & DSR_WEF) == 0)
+ return;
+ udelay(10);
+ }
+ dev_err(&pdata->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 rtc_drv_data *pdata, u32 val, int reg)
+{
+ int ret;
+ int rc = 0;
+
+ /* serialize register writes */
+ mutex_lock(&pdata->write_mutex);
+
+ /* enable the write-complete interrupt */
+ di_int_enable(pdata, DIER_WCIE);
+
+ pdata->dsr = 0;
+
+ /* do the register write */
+ di_write(pdata, val, reg);
+
+ /* wait for the write to finish */
+ ret = wait_event_interruptible_timeout(pdata->write_wait,
+ pdata->dsr & (DSR_WCF | DSR_WEF),
+ 1 * HZ);
+ if (ret == 0)
+ dev_warn(&pdata->pdev->dev, "Write-wait timeout\n");
+
+ /* check for write error */
+ if (pdata->dsr & DSR_WEF) {
+ clear_write_error(pdata);
+ rc = -EIO;
+ }
+ mutex_unlock(&pdata->write_mutex);
+ return rc;
+}
+
+/*
+ * rtc device ioctl
+ *
+ * The rtc framework handles the basic rtc ioctls on behalf
+ * of the driver by calling the functions registered in the
+ * rtc_ops structure.
+ */
+static int dryice_rtc_ioctl(struct device *dev, unsigned int cmd,
+ unsigned long arg)
+{
+ struct rtc_drv_data *pdata = dev_get_drvdata(dev);
+
+ dev_dbg(dev, "%s(0x%x)\n", __func__, cmd);
+ switch (cmd) {
+ case RTC_AIE_OFF: /* alarm disable */
+ di_int_disable(pdata, DIER_CAIE);
+ return 0;
+
+ case RTC_AIE_ON: /* alarm enable */
+ di_int_enable(pdata, DIER_CAIE);
+ return 0;
+ }
+ return -ENOIOCTLCMD;
+}
+
+/*
+ * 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 rtc_drv_data *pdata = dev_get_drvdata(dev);
+ unsigned long now;
+
+ dev_dbg(dev, "%s\n", __func__);
+ now = di_read(pdata, 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 device *dev, struct rtc_time *tm)
+{
+ struct rtc_drv_data *pdata = dev_get_drvdata(dev);
+ unsigned long now;
+ int rc;
+
+ dev_dbg(dev, "%s\n", __func__);
+ rc = rtc_tm_to_time(tm, &now);
+ if (rc == 0) {
+ /* zero the fractional part first */
+ di_write_wait_err(pdata, 0, DTCLR, rc, err);
+ di_write_wait_err(pdata, now, DTCMR, rc, err);
+ }
+err:
+ return rc;
+}
+
+/*
+ * 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 rtc_drv_data *pdata = dev_get_drvdata(dev);
+ u32 dcamr;
+
+ dev_dbg(dev, "%s\n", __func__);
+ dcamr = di_read(pdata, DCAMR);
+ rtc_time_to_tm(dcamr, &alarm->time);
+
+ /* alarm is enabled if the interrupt is enabled */
+ alarm->enabled = (di_read(pdata, DIER) & DIER_CAIE) != 0;
+
+ /* don't allow the DSR read to mess up DSR_WCF */
+ mutex_lock(&pdata->write_mutex);
+
+ /* alarm is pending if the alarm flag is set */
+ alarm->pending = (di_read(pdata, DSR) & DSR_CAF) != 0;
+
+ mutex_unlock(&pdata->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 rtc_drv_data *pdata = dev_get_drvdata(dev);
+ unsigned long now;
+ unsigned long alarm_time;
+ int rc;
+
+ dev_dbg(dev, "%s\n", __func__);
+ rc = rtc_tm_to_time(&alarm->time, &alarm_time);
+ if (rc)
+ return rc;
+
+ /* don't allow setting alarm in the past */
+ now = di_read(pdata, DTCMR);
+ if (alarm_time < now)
+ return -EINVAL;
+
+ /* write the new alarm time */
+ di_write_wait_err(pdata, (u32)alarm_time, DCAMR, rc, err);
+
+ if (alarm->enabled)
+ di_int_enable(pdata, DIER_CAIE); /* enable alarm intr */
+ else
+ di_int_disable(pdata, DIER_CAIE); /* disable alarm intr */
+err:
+ return rc;
+}
+
+static struct rtc_class_ops dryice_rtc_ops = {
+ .ioctl = dryice_rtc_ioctl,
+ .read_time = dryice_rtc_read_time,
+ .set_time = dryice_rtc_set_time,
+ .read_alarm = dryice_rtc_read_alarm,
+ .set_alarm = dryice_rtc_set_alarm,
+};
+
+/*
+ * dryice "normal" interrupt handler
+ */
+static irqreturn_t dryice_norm_irq(int irq, void *dev_id)
+{
+ struct rtc_drv_data *pdata = dev_id;
+ u32 dsr, dier;
+ irqreturn_t rc = IRQ_NONE;
+
+ dier = di_read(pdata, DIER);
+
+ /* 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(&pdata->write_wait.task_list))
+ return rc;
+
+ /* DSR_WCF clears itself on DSR read */
+ dsr = di_read(pdata, DSR);
+ if ((dsr & (DSR_WCF | DSR_WEF))) {
+ /* mask the interrupt */
+ di_int_disable(pdata, DIER_WCIE);
+
+ /* save the dsr value for the wait queue */
+ pdata->dsr |= dsr;
+
+ wake_up_interruptible(&pdata->write_wait);
+ rc = IRQ_HANDLED;
+ }
+ }
+
+ /* handle the alarm case */
+ if ((dier & DIER_CAIE)) {
+ /* DSR_WCF clears itself on DSR read */
+ dsr = di_read(pdata, DSR);
+ if (dsr & DSR_CAF) {
+ /* mask the interrupt */
+ di_int_disable(pdata, DIER_CAIE);
+
+ /* finish alarm in user context */
+ schedule_work(&pdata->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 rtc_drv_data *pdata = container_of(work, struct rtc_drv_data,
+ work);
+ int rc;
+
+ /* dismiss the interrupt (ignore error) */
+ di_write_wait_err(pdata, DSR_CAF, DSR, rc, err);
+err:
+ /*
+ * pass the alarm event to the rtc framework. note that
+ * rtc_update_irq expects to be called with interrupts off.
+ */
+ local_irq_disable();
+ rtc_update_irq(pdata->rtc, 1, RTC_AF | RTC_IRQF);
+ local_irq_enable();
+}
+
+/*
+ * probe for dryice rtc device
+ */
+static int dryice_rtc_probe(struct platform_device *pdev)
+{
+ struct rtc_device *rtc;
+ struct resource *res;
+ struct rtc_drv_data *pdata = NULL;
+ void __iomem *ioaddr = NULL;
+ int rc = 0;
+
+ dev_dbg(&pdev->dev, "%s\n", __func__);
+
+ res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+ if (!res)
+ return -ENODEV;
+
+ pdata = kzalloc(sizeof(*pdata), GFP_KERNEL);
+ if (!pdata)
+ return -ENOMEM;
+
+ pdata->pdev = pdev;
+ pdata->irq = -1;
+ pdata->size = res->end - res->start + 1;
+
+ if (!request_mem_region(res->start, pdata->size, pdev->name)) {
+ rc = -EBUSY;
+ goto err;
+ }
+ pdata->baseaddr = res->start;
+ ioaddr = ioremap(pdata->baseaddr, pdata->size);
+ if (!ioaddr) {
+ rc = -ENOMEM;
+ goto err;
+ }
+ pdata->ioaddr = ioaddr;
+ pdata->irq = platform_get_irq(pdev, 0);
+
+ init_waitqueue_head(&pdata->write_wait);
+
+ INIT_WORK(&pdata->work, dryice_work);
+
+ mutex_init(&pdata->write_mutex);
+
+ pdata->clk = clk_get(NULL, "dryice_clk");
+ clk_enable(pdata->clk);
+
+ if (pdata->irq >= 0) {
+ if (request_irq(pdata->irq, dryice_norm_irq, IRQF_SHARED,
+ pdev->name, pdata) < 0) {
+ dev_warn(&pdev->dev, "interrupt not available.\n");
+ pdata->irq = -1;
+ goto err;
+ }
+ }
+
+ /*
+ * Initialize dryice hardware
+ */
+
+ /* put dryice into valid state */
+ if (di_read(pdata, DSR) & DSR_NVF)
+ di_write_wait_err(pdata, DSR_NVF | DSR_SVF, DSR, rc, err);
+
+ /* mask alarm interrupt */
+ di_int_disable(pdata, DIER_CAIE);
+
+ /* initialize alarm */
+ di_write_wait_err(pdata, DCAMR_UNSET, DCAMR, rc, err);
+ di_write_wait_err(pdata, 0, DCALR, rc, err);
+
+ /* clear alarm flag */
+ if (di_read(pdata, DSR) & DSR_CAF)
+ di_write_wait_err(pdata, DSR_CAF, DSR, rc, err);
+
+ /* the timer won't count if it has never been written to */
+ if (!di_read(pdata, DTCMR))
+ di_write_wait_err(pdata, 0, DTCMR, rc, err);
+
+ /* start keeping time */
+ if (!(di_read(pdata, DCR) & DCR_TCE))
+ di_write_wait_err(pdata, di_read(pdata, DCR) | DCR_TCE, DCR,
+ rc, err);
+
+ rtc = rtc_device_register(pdev->name, &pdev->dev,
+ &dryice_rtc_ops, THIS_MODULE);
+ if (IS_ERR(rtc)) {
+ rc = PTR_ERR(rtc);
+ goto err;
+ }
+ pdata->rtc = rtc;
+ platform_set_drvdata(pdev, pdata);
+
+ return 0;
+err:
+ if (pdata->rtc)
+ rtc_device_unregister(pdata->rtc);
+
+ if (pdata->irq >= 0)
+ free_irq(pdata->irq, pdata);
+
+ if (pdata->clk) {
+ clk_disable(pdata->clk);
+ clk_put(pdata->clk);
+ }
+
+ if (pdata->ioaddr)
+ iounmap(pdata->ioaddr);
+
+ if (pdata->baseaddr)
+ release_mem_region(pdata->baseaddr, pdata->size);
+
+ kfree(pdata);
+
+ return rc;
+}
+
+static int __exit dryice_rtc_remove(struct platform_device *pdev)
+{
+ struct rtc_drv_data *pdata = platform_get_drvdata(pdev);
+
+ flush_scheduled_work();
+
+ if (pdata->rtc)
+ rtc_device_unregister(pdata->rtc);
+
+ /* mask alarm interrupt */
+ di_int_disable(pdata, DIER_CAIE);
+
+ if (pdata->irq >= 0)
+ free_irq(pdata->irq, pdata);
+
+ if (pdata->clk) {
+ clk_disable(pdata->clk);
+ clk_put(pdata->clk);
+ }
+
+ if (pdata->ioaddr)
+ iounmap(pdata->ioaddr);
+
+ if (pdata->baseaddr)
+ release_mem_region(pdata->baseaddr, pdata->size);
+
+ kfree(pdata);
+
+ return 0;
+}
+
+static struct platform_driver dryice_rtc_driver = {
+ .driver = {
+ .name = "imxdi_rtc",
+ .owner = THIS_MODULE,
+ },
+ .probe = dryice_rtc_probe,
+ .remove = __exit_p(dryice_rtc_remove),
+};
+
+static int __init dryice_rtc_init(void)
+{
+ pr_info("IMXDI Realtime Clock Driver (RTC)\n");
+ return platform_driver_register(&dryice_rtc_driver);
+}
+
+static void __exit dryice_rtc_exit(void)
+{
+ platform_driver_unregister(&dryice_rtc_driver);
+}
+
+module_init(dryice_rtc_init);
+module_exit(dryice_rtc_exit);
+
+MODULE_AUTHOR("Freescale Semiconductor, Inc.");
+MODULE_DESCRIPTION("IMXDI Realtime Clock Driver (RTC)");
+MODULE_LICENSE("GPL");
generated by cgit v1.2.3 (git 2.0.4) at 2025-01-15 00:36:47 +0000