linux/drivers/rtc/rtc-mrst.c
Feng Tang d3e1884bc5 x86, mrst: Add explanation for using 1960 as the year offset for vrtc
Explain the reason for the apparently odd choice of year offset so we don't
get more questions about it.

Signed-off-by: Feng Tang <feng.tang@intel.com>
Signed-off-by: Alan Cox <alan@linux.intel.com>
LKML-Reference: <20101117121050.9998.89348.stgit@localhost.localdomain>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2010-11-17 13:53:46 +01:00

582 lines
13 KiB
C

/*
* rtc-mrst.c: Driver for Moorestown virtual RTC
*
* (C) Copyright 2009 Intel Corporation
* Author: Jacob Pan (jacob.jun.pan@intel.com)
* Feng Tang (feng.tang@intel.com)
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; version 2
* of the License.
*
* Note:
* VRTC is emulated by system controller firmware, the real HW
* RTC is located in the PMIC device. SCU FW shadows PMIC RTC
* in a memory mapped IO space that is visible to the host IA
* processor.
*
* This driver is based upon drivers/rtc/rtc-cmos.c
*/
/*
* Note:
* * vRTC only supports binary mode and 24H mode
* * vRTC only support PIE and AIE, no UIE, and its PIE only happens
* at 23:59:59pm everyday, no support for adjustable frequency
* * Alarm function is also limited to hr/min/sec.
*/
#include <linux/mod_devicetable.h>
#include <linux/platform_device.h>
#include <linux/interrupt.h>
#include <linux/spinlock.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/sfi.h>
#include <asm-generic/rtc.h>
#include <asm/intel_scu_ipc.h>
#include <asm/mrst.h>
#include <asm/mrst-vrtc.h>
struct mrst_rtc {
struct rtc_device *rtc;
struct device *dev;
int irq;
struct resource *iomem;
u8 enabled_wake;
u8 suspend_ctrl;
};
static const char driver_name[] = "rtc_mrst";
#define RTC_IRQMASK (RTC_PF | RTC_AF)
static inline int is_intr(u8 rtc_intr)
{
if (!(rtc_intr & RTC_IRQF))
return 0;
return rtc_intr & RTC_IRQMASK;
}
/*
* rtc_time's year contains the increment over 1900, but vRTC's YEAR
* register can't be programmed to value larger than 0x64, so vRTC
* driver chose to use 1960 (1970 is UNIX time start point) as the base,
* and does the translation at read/write time.
*
* Why not just use 1970 as the offset? it's because using 1960 will
* make it consistent in leap year setting for both vrtc and low-level
* physical rtc devices.
*/
static int mrst_read_time(struct device *dev, struct rtc_time *time)
{
unsigned long flags;
if (rtc_is_updating())
mdelay(20);
spin_lock_irqsave(&rtc_lock, flags);
time->tm_sec = vrtc_cmos_read(RTC_SECONDS);
time->tm_min = vrtc_cmos_read(RTC_MINUTES);
time->tm_hour = vrtc_cmos_read(RTC_HOURS);
time->tm_mday = vrtc_cmos_read(RTC_DAY_OF_MONTH);
time->tm_mon = vrtc_cmos_read(RTC_MONTH);
time->tm_year = vrtc_cmos_read(RTC_YEAR);
spin_unlock_irqrestore(&rtc_lock, flags);
/* Adjust for the 1960/1900 */
time->tm_year += 60;
time->tm_mon--;
return RTC_24H;
}
static int mrst_set_time(struct device *dev, struct rtc_time *time)
{
int ret;
unsigned long flags;
unsigned char mon, day, hrs, min, sec;
unsigned int yrs;
yrs = time->tm_year;
mon = time->tm_mon + 1; /* tm_mon starts at zero */
day = time->tm_mday;
hrs = time->tm_hour;
min = time->tm_min;
sec = time->tm_sec;
if (yrs < 70 || yrs > 138)
return -EINVAL;
yrs -= 60;
spin_lock_irqsave(&rtc_lock, flags);
vrtc_cmos_write(yrs, RTC_YEAR);
vrtc_cmos_write(mon, RTC_MONTH);
vrtc_cmos_write(day, RTC_DAY_OF_MONTH);
vrtc_cmos_write(hrs, RTC_HOURS);
vrtc_cmos_write(min, RTC_MINUTES);
vrtc_cmos_write(sec, RTC_SECONDS);
spin_unlock_irqrestore(&rtc_lock, flags);
ret = intel_scu_ipc_simple_command(IPCMSG_VRTC, IPC_CMD_VRTC_SETTIME);
return ret;
}
static int mrst_read_alarm(struct device *dev, struct rtc_wkalrm *t)
{
struct mrst_rtc *mrst = dev_get_drvdata(dev);
unsigned char rtc_control;
if (mrst->irq <= 0)
return -EIO;
/* Basic alarms only support hour, minute, and seconds fields.
* Some also support day and month, for alarms up to a year in
* the future.
*/
t->time.tm_mday = -1;
t->time.tm_mon = -1;
t->time.tm_year = -1;
/* vRTC only supports binary mode */
spin_lock_irq(&rtc_lock);
t->time.tm_sec = vrtc_cmos_read(RTC_SECONDS_ALARM);
t->time.tm_min = vrtc_cmos_read(RTC_MINUTES_ALARM);
t->time.tm_hour = vrtc_cmos_read(RTC_HOURS_ALARM);
rtc_control = vrtc_cmos_read(RTC_CONTROL);
spin_unlock_irq(&rtc_lock);
t->enabled = !!(rtc_control & RTC_AIE);
t->pending = 0;
return 0;
}
static void mrst_checkintr(struct mrst_rtc *mrst, unsigned char rtc_control)
{
unsigned char rtc_intr;
/*
* NOTE after changing RTC_xIE bits we always read INTR_FLAGS;
* allegedly some older rtcs need that to handle irqs properly
*/
rtc_intr = vrtc_cmos_read(RTC_INTR_FLAGS);
rtc_intr &= (rtc_control & RTC_IRQMASK) | RTC_IRQF;
if (is_intr(rtc_intr))
rtc_update_irq(mrst->rtc, 1, rtc_intr);
}
static void mrst_irq_enable(struct mrst_rtc *mrst, unsigned char mask)
{
unsigned char rtc_control;
/*
* Flush any pending IRQ status, notably for update irqs,
* before we enable new IRQs
*/
rtc_control = vrtc_cmos_read(RTC_CONTROL);
mrst_checkintr(mrst, rtc_control);
rtc_control |= mask;
vrtc_cmos_write(rtc_control, RTC_CONTROL);
mrst_checkintr(mrst, rtc_control);
}
static void mrst_irq_disable(struct mrst_rtc *mrst, unsigned char mask)
{
unsigned char rtc_control;
rtc_control = vrtc_cmos_read(RTC_CONTROL);
rtc_control &= ~mask;
vrtc_cmos_write(rtc_control, RTC_CONTROL);
mrst_checkintr(mrst, rtc_control);
}
static int mrst_set_alarm(struct device *dev, struct rtc_wkalrm *t)
{
struct mrst_rtc *mrst = dev_get_drvdata(dev);
unsigned char hrs, min, sec;
int ret = 0;
if (!mrst->irq)
return -EIO;
hrs = t->time.tm_hour;
min = t->time.tm_min;
sec = t->time.tm_sec;
spin_lock_irq(&rtc_lock);
/* Next rtc irq must not be from previous alarm setting */
mrst_irq_disable(mrst, RTC_AIE);
/* Update alarm */
vrtc_cmos_write(hrs, RTC_HOURS_ALARM);
vrtc_cmos_write(min, RTC_MINUTES_ALARM);
vrtc_cmos_write(sec, RTC_SECONDS_ALARM);
spin_unlock_irq(&rtc_lock);
ret = intel_scu_ipc_simple_command(IPCMSG_VRTC, IPC_CMD_VRTC_SETALARM);
if (ret)
return ret;
spin_lock_irq(&rtc_lock);
if (t->enabled)
mrst_irq_enable(mrst, RTC_AIE);
spin_unlock_irq(&rtc_lock);
return 0;
}
static int mrst_irq_set_state(struct device *dev, int enabled)
{
struct mrst_rtc *mrst = dev_get_drvdata(dev);
unsigned long flags;
if (!mrst->irq)
return -ENXIO;
spin_lock_irqsave(&rtc_lock, flags);
if (enabled)
mrst_irq_enable(mrst, RTC_PIE);
else
mrst_irq_disable(mrst, RTC_PIE);
spin_unlock_irqrestore(&rtc_lock, flags);
return 0;
}
#if defined(CONFIG_RTC_INTF_DEV) || defined(CONFIG_RTC_INTF_DEV_MODULE)
/* Currently, the vRTC doesn't support UIE ON/OFF */
static int
mrst_rtc_ioctl(struct device *dev, unsigned int cmd, unsigned long arg)
{
struct mrst_rtc *mrst = dev_get_drvdata(dev);
unsigned long flags;
switch (cmd) {
case RTC_AIE_OFF:
case RTC_AIE_ON:
if (!mrst->irq)
return -EINVAL;
break;
default:
/* PIE ON/OFF is handled by mrst_irq_set_state() */
return -ENOIOCTLCMD;
}
spin_lock_irqsave(&rtc_lock, flags);
switch (cmd) {
case RTC_AIE_OFF: /* alarm off */
mrst_irq_disable(mrst, RTC_AIE);
break;
case RTC_AIE_ON: /* alarm on */
mrst_irq_enable(mrst, RTC_AIE);
break;
}
spin_unlock_irqrestore(&rtc_lock, flags);
return 0;
}
#else
#define mrst_rtc_ioctl NULL
#endif
#if defined(CONFIG_RTC_INTF_PROC) || defined(CONFIG_RTC_INTF_PROC_MODULE)
static int mrst_procfs(struct device *dev, struct seq_file *seq)
{
unsigned char rtc_control, valid;
spin_lock_irq(&rtc_lock);
rtc_control = vrtc_cmos_read(RTC_CONTROL);
valid = vrtc_cmos_read(RTC_VALID);
spin_unlock_irq(&rtc_lock);
return seq_printf(seq,
"periodic_IRQ\t: %s\n"
"alarm\t\t: %s\n"
"BCD\t\t: no\n"
"periodic_freq\t: daily (not adjustable)\n",
(rtc_control & RTC_PIE) ? "on" : "off",
(rtc_control & RTC_AIE) ? "on" : "off");
}
#else
#define mrst_procfs NULL
#endif
static const struct rtc_class_ops mrst_rtc_ops = {
.ioctl = mrst_rtc_ioctl,
.read_time = mrst_read_time,
.set_time = mrst_set_time,
.read_alarm = mrst_read_alarm,
.set_alarm = mrst_set_alarm,
.proc = mrst_procfs,
.irq_set_state = mrst_irq_set_state,
};
static struct mrst_rtc mrst_rtc;
/*
* When vRTC IRQ is captured by SCU FW, FW will clear the AIE bit in
* Reg B, so no need for this driver to clear it
*/
static irqreturn_t mrst_rtc_irq(int irq, void *p)
{
u8 irqstat;
spin_lock(&rtc_lock);
/* This read will clear all IRQ flags inside Reg C */
irqstat = vrtc_cmos_read(RTC_INTR_FLAGS);
spin_unlock(&rtc_lock);
irqstat &= RTC_IRQMASK | RTC_IRQF;
if (is_intr(irqstat)) {
rtc_update_irq(p, 1, irqstat);
return IRQ_HANDLED;
}
return IRQ_NONE;
}
static int __init
vrtc_mrst_do_probe(struct device *dev, struct resource *iomem, int rtc_irq)
{
int retval = 0;
unsigned char rtc_control;
/* There can be only one ... */
if (mrst_rtc.dev)
return -EBUSY;
if (!iomem)
return -ENODEV;
iomem = request_mem_region(iomem->start,
iomem->end + 1 - iomem->start,
driver_name);
if (!iomem) {
dev_dbg(dev, "i/o mem already in use.\n");
return -EBUSY;
}
mrst_rtc.irq = rtc_irq;
mrst_rtc.iomem = iomem;
mrst_rtc.rtc = rtc_device_register(driver_name, dev,
&mrst_rtc_ops, THIS_MODULE);
if (IS_ERR(mrst_rtc.rtc)) {
retval = PTR_ERR(mrst_rtc.rtc);
goto cleanup0;
}
mrst_rtc.dev = dev;
dev_set_drvdata(dev, &mrst_rtc);
rename_region(iomem, dev_name(&mrst_rtc.rtc->dev));
spin_lock_irq(&rtc_lock);
mrst_irq_disable(&mrst_rtc, RTC_PIE | RTC_AIE);
rtc_control = vrtc_cmos_read(RTC_CONTROL);
spin_unlock_irq(&rtc_lock);
if (!(rtc_control & RTC_24H) || (rtc_control & (RTC_DM_BINARY)))
dev_dbg(dev, "TODO: support more than 24-hr BCD mode\n");
if (rtc_irq) {
retval = request_irq(rtc_irq, mrst_rtc_irq,
IRQF_DISABLED, dev_name(&mrst_rtc.rtc->dev),
mrst_rtc.rtc);
if (retval < 0) {
dev_dbg(dev, "IRQ %d is already in use, err %d\n",
rtc_irq, retval);
goto cleanup1;
}
}
dev_dbg(dev, "initialised\n");
return 0;
cleanup1:
mrst_rtc.dev = NULL;
rtc_device_unregister(mrst_rtc.rtc);
cleanup0:
release_region(iomem->start, iomem->end + 1 - iomem->start);
dev_err(dev, "rtc-mrst: unable to initialise\n");
return retval;
}
static void rtc_mrst_do_shutdown(void)
{
spin_lock_irq(&rtc_lock);
mrst_irq_disable(&mrst_rtc, RTC_IRQMASK);
spin_unlock_irq(&rtc_lock);
}
static void __exit rtc_mrst_do_remove(struct device *dev)
{
struct mrst_rtc *mrst = dev_get_drvdata(dev);
struct resource *iomem;
rtc_mrst_do_shutdown();
if (mrst->irq)
free_irq(mrst->irq, mrst->rtc);
rtc_device_unregister(mrst->rtc);
mrst->rtc = NULL;
iomem = mrst->iomem;
release_region(iomem->start, iomem->end + 1 - iomem->start);
mrst->iomem = NULL;
mrst->dev = NULL;
dev_set_drvdata(dev, NULL);
}
#ifdef CONFIG_PM
static int mrst_suspend(struct device *dev, pm_message_t mesg)
{
struct mrst_rtc *mrst = dev_get_drvdata(dev);
unsigned char tmp;
/* Only the alarm might be a wakeup event source */
spin_lock_irq(&rtc_lock);
mrst->suspend_ctrl = tmp = vrtc_cmos_read(RTC_CONTROL);
if (tmp & (RTC_PIE | RTC_AIE)) {
unsigned char mask;
if (device_may_wakeup(dev))
mask = RTC_IRQMASK & ~RTC_AIE;
else
mask = RTC_IRQMASK;
tmp &= ~mask;
vrtc_cmos_write(tmp, RTC_CONTROL);
mrst_checkintr(mrst, tmp);
}
spin_unlock_irq(&rtc_lock);
if (tmp & RTC_AIE) {
mrst->enabled_wake = 1;
enable_irq_wake(mrst->irq);
}
dev_dbg(&mrst_rtc.rtc->dev, "suspend%s, ctrl %02x\n",
(tmp & RTC_AIE) ? ", alarm may wake" : "",
tmp);
return 0;
}
/*
* We want RTC alarms to wake us from the deep power saving state
*/
static inline int mrst_poweroff(struct device *dev)
{
return mrst_suspend(dev, PMSG_HIBERNATE);
}
static int mrst_resume(struct device *dev)
{
struct mrst_rtc *mrst = dev_get_drvdata(dev);
unsigned char tmp = mrst->suspend_ctrl;
/* Re-enable any irqs previously active */
if (tmp & RTC_IRQMASK) {
unsigned char mask;
if (mrst->enabled_wake) {
disable_irq_wake(mrst->irq);
mrst->enabled_wake = 0;
}
spin_lock_irq(&rtc_lock);
do {
vrtc_cmos_write(tmp, RTC_CONTROL);
mask = vrtc_cmos_read(RTC_INTR_FLAGS);
mask &= (tmp & RTC_IRQMASK) | RTC_IRQF;
if (!is_intr(mask))
break;
rtc_update_irq(mrst->rtc, 1, mask);
tmp &= ~RTC_AIE;
} while (mask & RTC_AIE);
spin_unlock_irq(&rtc_lock);
}
dev_dbg(&mrst_rtc.rtc->dev, "resume, ctrl %02x\n", tmp);
return 0;
}
#else
#define mrst_suspend NULL
#define mrst_resume NULL
static inline int mrst_poweroff(struct device *dev)
{
return -ENOSYS;
}
#endif
static int __init vrtc_mrst_platform_probe(struct platform_device *pdev)
{
return vrtc_mrst_do_probe(&pdev->dev,
platform_get_resource(pdev, IORESOURCE_MEM, 0),
platform_get_irq(pdev, 0));
}
static int __exit vrtc_mrst_platform_remove(struct platform_device *pdev)
{
rtc_mrst_do_remove(&pdev->dev);
return 0;
}
static void vrtc_mrst_platform_shutdown(struct platform_device *pdev)
{
if (system_state == SYSTEM_POWER_OFF && !mrst_poweroff(&pdev->dev))
return;
rtc_mrst_do_shutdown();
}
MODULE_ALIAS("platform:vrtc_mrst");
static struct platform_driver vrtc_mrst_platform_driver = {
.probe = vrtc_mrst_platform_probe,
.remove = __exit_p(vrtc_mrst_platform_remove),
.shutdown = vrtc_mrst_platform_shutdown,
.driver = {
.name = (char *) driver_name,
.suspend = mrst_suspend,
.resume = mrst_resume,
}
};
static int __init vrtc_mrst_init(void)
{
return platform_driver_register(&vrtc_mrst_platform_driver);
}
static void __exit vrtc_mrst_exit(void)
{
platform_driver_unregister(&vrtc_mrst_platform_driver);
}
module_init(vrtc_mrst_init);
module_exit(vrtc_mrst_exit);
MODULE_AUTHOR("Jacob Pan; Feng Tang");
MODULE_DESCRIPTION("Driver for Moorestown virtual RTC");
MODULE_LICENSE("GPL");