rtc: Add drivers/rtc/rtc-mrst.c

Provide the standard kernel rtc driver interface on top of the vrtc layer
added in the previous patch.

Signed-off-by: Feng Tang <[e-mail]>
LKML-Reference: <[e-mail]>
[Fixed swapped arguments on IPC]
Signed-off-by: Arjan van de Ven <[e-mail]>
[Cleaned up and the device creation moved to arch/x86/platform]
Signed-off-by: Alan Cox <[e-mail]>
Signed-off-by: Thomas Gleixner <[e-mail]>

arch/x86/platform/mrst/vrtc.c

···
 #include <linux/kernel.h>
 #include <linux/init.h>
 #include <linux/sfi.h>
+#include <linux/platform_device.h>
 
 #include <asm/mrst.h>
 #include <asm/mrst-vrtc.h>
···
 	x86_platform.get_wallclock = vrtc_get_time;
 	x86_platform.set_wallclock = vrtc_set_mmss;
 }
+
+/*
+ * The Moorestown platform has a memory mapped virtual RTC device that emulates
+ * the programming interface of the RTC.
+ */
+
+static struct resource vrtc_resources[] = {
+	[0] = {
+		.flags	= IORESOURCE_MEM,
+	},
+	[1] = {
+		.flags	= IORESOURCE_IRQ,
+	}
+};
+
+static struct platform_device vrtc_device = {
+	.name		= "rtc_mrst",
+	.id		= -1,
+	.resource	= vrtc_resources,
+	.num_resources	= ARRAY_SIZE(vrtc_resources),
+};
+
+/* Register the RTC device if appropriate */
+static int __init mrst_device_create(void)
+{
+	/* No Moorestown, no device */
+	if (!mrst_identify_cpu())
+		return -ENODEV;
+	/* No timer, no device */
+	if (!sfi_mrtc_num)
+		return -ENODEV;
+
+	/* iomem resource */
+	vrtc_resources[0].start = sfi_mrtc_array[0].phys_addr;
+	vrtc_resources[0].end = sfi_mrtc_array[0].phys_addr +
+				MRST_VRTC_MAP_SZ;
+	/* irq resource */
+	vrtc_resources[1].start = sfi_mrtc_array[0].irq;
+	vrtc_resources[1].end = sfi_mrtc_array[0].irq;
+
+	platform_device_register(&vrtc_device);
+	return 0;
+}
+
+module_init(mrst_device_create);

drivers/rtc/Kconfig

···
 	  This driver can also be built as a module. If so, the module
 	  will be called rtc-cmos.
 
+config RTC_DRV_VRTC
+	tristate "Virtual RTC for Moorestown platforms"
+	depends on X86_MRST
+	default y if X86_MRST
+
+	help
+	Say "yes" here to get direct support for the real time clock
+	found on Moorestown platforms. The VRTC is a emulated RTC that
+	derives its clock source from a real RTC in the PMIC. The MC146818
+	style programming interface is mostly conserved, but any
+	updates are done via IPC calls to the system controller FW.
+
 config RTC_DRV_DS1216
 	tristate "Dallas DS1216"
 	depends on SNI_RM

drivers/rtc/Makefile

···
 obj-$(CONFIG_RTC_DRV_COH901331)	+= rtc-coh901331.o
 obj-$(CONFIG_RTC_DRV_DAVINCI)	+= rtc-davinci.o
 obj-$(CONFIG_RTC_DRV_DM355EVM)	+= rtc-dm355evm.o
+obj-$(CONFIG_RTC_DRV_VRTC)	+= rtc-mrst.o
 obj-$(CONFIG_RTC_DRV_DS1216)	+= rtc-ds1216.o
 obj-$(CONFIG_RTC_DRV_DS1286)	+= rtc-ds1286.o
 obj-$(CONFIG_RTC_DRV_DS1302)	+= rtc-ds1302.o

drivers/rtc/rtc-mrst.c

···
+/*
+ * rtc-mrst.c: Driver for Moorestown virtual RTC
+ *
+ * (C) Copyright 2009 Intel Corporation
+ * Author: Jacob Pan ([e-mail])
+ *	   Feng Tang ([e-mail])
+ *
+ * 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
+ */
+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");