/* * 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 <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_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 */ /** * struct imxdi_dev - private imxdi rtc data * @pdev: pionter to platform dev * @rtc: pointer to rtc struct * @ioaddr: IO registers pointer * @irq: dryice normal interrupt * @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; int irq; struct clk *clk; u32 dsr; spinlock_t irq_lock; wait_queue_head_t write_wait; struct mutex write_mutex; struct work_struct work; }; /* * 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); __raw_writel(__raw_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); __raw_writel(__raw_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 */ __raw_writel(DSR_WEF, imxdi->ioaddr + DSR); /* wait for it to take effect */ for (cnt = 0; cnt < 1000; cnt++) { if ((__raw_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 */ __raw_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 = __raw_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_mmss(struct device *dev, unsigned long secs) { struct imxdi_dev *imxdi = dev_get_drvdata(dev); int rc; /* zero the fractional part first */ rc = di_write_wait(imxdi, 0, DTCLR); if (rc == 0) rc = di_write_wait(imxdi, secs, DTCMR); return rc; } 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 = __raw_readl(imxdi->ioaddr + DCAMR); rtc_time_to_tm(dcamr, &alarm->time); /* alarm is enabled if the interrupt is enabled */ alarm->enabled = (__raw_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 = (__raw_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); unsigned long now; unsigned long alarm_time; int rc; rc = rtc_tm_to_time(&alarm->time, &alarm_time); if (rc) return rc; /* don't allow setting alarm in the past */ now = __raw_readl(imxdi->ioaddr + DTCMR); if (alarm_time < now) return -EINVAL; /* write the new alarm time */ rc = di_write_wait(imxdi, (u32)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 struct rtc_class_ops dryice_rtc_ops = { .read_time = dryice_rtc_read_time, .set_mmss = dryice_rtc_set_mmss, .alarm_irq_enable = dryice_rtc_alarm_irq_enable, .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 imxdi_dev *imxdi = dev_id; u32 dsr, dier; irqreturn_t rc = IRQ_NONE; dier = __raw_readl(imxdi->ioaddr + 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(&imxdi->write_wait.task_list)) return rc; /* DSR_WCF clears itself on DSR read */ dsr = __raw_readl(imxdi->ioaddr + DSR); 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 */ dsr = __raw_readl(imxdi->ioaddr + DSR); 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 resource *res; struct imxdi_dev *imxdi; int rc; imxdi = devm_kzalloc(&pdev->dev, sizeof(*imxdi), GFP_KERNEL); if (!imxdi) return -ENOMEM; imxdi->pdev = pdev; res = platform_get_resource(pdev, IORESOURCE_MEM, 0); imxdi->ioaddr = devm_ioremap_resource(&pdev->dev, res); if (IS_ERR(imxdi->ioaddr)) return PTR_ERR(imxdi->ioaddr); spin_lock_init(&imxdi->irq_lock); imxdi->irq = platform_get_irq(pdev, 0); if (imxdi->irq < 0) return imxdi->irq; init_waitqueue_head(&imxdi->write_wait); INIT_WORK(&imxdi->work, dryice_work); mutex_init(&imxdi->write_mutex); 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 */ __raw_writel(0, imxdi->ioaddr + DIER); rc = devm_request_irq(&pdev->dev, imxdi->irq, dryice_norm_irq, IRQF_SHARED, pdev->name, imxdi); if (rc) { dev_warn(&pdev->dev, "interrupt not available.\n"); goto err; } /* put dryice into valid state */ if (__raw_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 (__raw_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 (__raw_readl(imxdi->ioaddr + DTCMR) == 0) { rc = di_write_wait(imxdi, 0, DTCMR); if (rc) goto err; } /* start keeping time */ if (!(__raw_readl(imxdi->ioaddr + DCR) & DCR_TCE)) { rc = di_write_wait(imxdi, __raw_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); if (IS_ERR(imxdi->rtc)) { rc = PTR_ERR(imxdi->rtc); 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 */ __raw_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", .owner = THIS_MODULE, .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");