diff options
Diffstat (limited to 'drivers/rtc/rtc-imxdi.c')
| -rw-r--r-- | drivers/rtc/rtc-imxdi.c | 519 |
1 files changed, 519 insertions, 0 deletions
diff --git a/drivers/rtc/rtc-imxdi.c b/drivers/rtc/rtc-imxdi.c new file mode 100644 index 000000000000..2dd3c0163272 --- /dev/null +++ b/drivers/rtc/rtc-imxdi.c @@ -0,0 +1,519 @@ +/* + * 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/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 */ + +/** + * 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 dryice_rtc_probe(struct platform_device *pdev) +{ + struct resource *res; + struct imxdi_dev *imxdi; + int rc; + + res = platform_get_resource(pdev, IORESOURCE_MEM, 0); + if (!res) + return -ENODEV; + + imxdi = devm_kzalloc(&pdev->dev, sizeof(*imxdi), GFP_KERNEL); + if (!imxdi) + return -ENOMEM; + + imxdi->pdev = pdev; + + if (!devm_request_mem_region(&pdev->dev, res->start, resource_size(res), + pdev->name)) + return -EBUSY; + + imxdi->ioaddr = devm_ioremap(&pdev->dev, res->start, + resource_size(res)); + if (imxdi->ioaddr == NULL) + return -ENOMEM; + + 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 = clk_get(&pdev->dev, NULL); + if (IS_ERR(imxdi->clk)) + return PTR_ERR(imxdi->clk); + clk_enable(imxdi->clk); + + /* + * 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 = rtc_device_register(pdev->name, &pdev->dev, + &dryice_rtc_ops, THIS_MODULE); + if (IS_ERR(imxdi->rtc)) { + rc = PTR_ERR(imxdi->rtc); + goto err; + } + + return 0; + +err: + clk_disable(imxdi->clk); + clk_put(imxdi->clk); + + return rc; +} + +static int __devexit 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); + + rtc_device_unregister(imxdi->rtc); + + clk_disable(imxdi->clk); + clk_put(imxdi->clk); + + return 0; +} + +static struct platform_driver dryice_rtc_driver = { + .driver = { + .name = "imxdi_rtc", + .owner = THIS_MODULE, + }, + .remove = __devexit_p(dryice_rtc_remove), +}; + +static int __init dryice_rtc_init(void) +{ + return platform_driver_probe(&dryice_rtc_driver, dryice_rtc_probe); +} + +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_AUTHOR("Baruch Siach <baruch@tkos.co.il>"); +MODULE_DESCRIPTION("IMX DryIce Realtime Clock Driver (RTC)"); +MODULE_LICENSE("GPL"); |