/*
* 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/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_prepare_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_unprepare(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_unprepare(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");
