1 files changed, 521 insertions, 0 deletions

diff --git a/drivers/rtc/rtc-mrst.c b/drivers/rtc/rtc-mrst.c
new file mode 100644
index 000000000..17bf5394e
--- /dev/null
+++ b/drivers/rtc/rtc-mrst.c
@@ -0,0 +1,521 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * 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)
+ *
+ * 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/mc146818rtc.h>
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/sfi.h>
+
+#include <asm/intel_scu_ipc.h>
+#include <asm/intel-mid.h>
+#include <asm/intel_mid_vrtc.h>
+
+struct mrst_rtc {
+	struct rtc_device	*rtc;
+	struct device		*dev;
+	int			irq;
+
+	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;
+}
+
+static inline unsigned char vrtc_is_updating(void)
+{
+	unsigned char uip;
+	unsigned long flags;
+
+	spin_lock_irqsave(&rtc_lock, flags);
+	uip = (vrtc_cmos_read(RTC_FREQ_SELECT) & RTC_UIP);
+	spin_unlock_irqrestore(&rtc_lock, flags);
+	return uip;
+}
+
+/*
+ * 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 1972 (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 1972 will
+ * make it consistent in leap year setting for both vrtc and low-level
+ * physical rtc devices. Then why not use 1960 as the offset? If we use
+ * 1960, for a device's first use, its YEAR register is 0 and the system
+ * year will be parsed as 1960 which is not a valid UNIX time and will
+ * cause many applications to fail mysteriously.
+ */
+static int mrst_read_time(struct device *dev, struct rtc_time *time)
+{
+	unsigned long flags;
+
+	if (vrtc_is_updating())
+		msleep(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 1972/1900 */
+	time->tm_year += 72;
+	time->tm_mon--;
+	return 0;
+}
+
+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 < 72 || yrs > 172)
+		return -EINVAL;
+	yrs -= 72;
+
+	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;
+
+	/* 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;
+}
+
+/* Currently, the vRTC doesn't support UIE ON/OFF */
+static int mrst_rtc_alarm_irq_enable(struct device *dev, unsigned int enabled)
+{
+	struct mrst_rtc	*mrst = dev_get_drvdata(dev);
+	unsigned long	flags;
+
+	spin_lock_irqsave(&rtc_lock, flags);
+	if (enabled)
+		mrst_irq_enable(mrst, RTC_AIE);
+	else
+		mrst_irq_disable(mrst, RTC_AIE);
+	spin_unlock_irqrestore(&rtc_lock, flags);
+	return 0;
+}
+
+
+#if IS_ENABLED(CONFIG_RTC_INTF_PROC)
+
+static int mrst_procfs(struct device *dev, struct seq_file *seq)
+{
+	unsigned char	rtc_control;
+
+	spin_lock_irq(&rtc_lock);
+	rtc_control = vrtc_cmos_read(RTC_CONTROL);
+	spin_unlock_irq(&rtc_lock);
+
+	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");
+
+	return 0;
+}
+
+#else
+#define	mrst_procfs	NULL
+#endif
+
+static const struct rtc_class_ops mrst_rtc_ops = {
+	.read_time	= mrst_read_time,
+	.set_time	= mrst_set_time,
+	.read_alarm	= mrst_read_alarm,
+	.set_alarm	= mrst_set_alarm,
+	.proc		= mrst_procfs,
+	.alarm_irq_enable = mrst_rtc_alarm_irq_enable,
+};
+
+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 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 = devm_request_mem_region(dev, iomem->start, resource_size(iomem),
+					driver_name);
+	if (!iomem) {
+		dev_dbg(dev, "i/o mem already in use.\n");
+		return -EBUSY;
+	}
+
+	mrst_rtc.irq = rtc_irq;
+	mrst_rtc.dev = dev;
+	dev_set_drvdata(dev, &mrst_rtc);
+
+	mrst_rtc.rtc = devm_rtc_allocate_device(dev);
+	if (IS_ERR(mrst_rtc.rtc))
+		return PTR_ERR(mrst_rtc.rtc);
+
+	mrst_rtc.rtc->ops = &mrst_rtc_ops;
+
+	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 = devm_request_irq(dev, rtc_irq, mrst_rtc_irq,
+					  0, 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 cleanup0;
+		}
+	}
+
+	retval = rtc_register_device(mrst_rtc.rtc);
+	if (retval)
+		goto cleanup0;
+
+	dev_dbg(dev, "initialised\n");
+	return 0;
+
+cleanup0:
+	mrst_rtc.dev = NULL;
+	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 rtc_mrst_do_remove(struct device *dev)
+{
+	struct mrst_rtc	*mrst = dev_get_drvdata(dev);
+
+	rtc_mrst_do_shutdown();
+
+	mrst->rtc = NULL;
+	mrst->dev = NULL;
+}
+
+#ifdef CONFIG_PM_SLEEP
+static int mrst_suspend(struct device *dev)
+{
+	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);
+}
+
+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;
+}
+
+static SIMPLE_DEV_PM_OPS(mrst_pm_ops, mrst_suspend, mrst_resume);
+#define MRST_PM_OPS (&mrst_pm_ops)
+
+#else
+#define MRST_PM_OPS NULL
+
+static inline int mrst_poweroff(struct device *dev)
+{
+	return -ENOSYS;
+}
+
+#endif
+
+static int 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 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		= vrtc_mrst_platform_remove,
+	.shutdown	= vrtc_mrst_platform_shutdown,
+	.driver = {
+		.name	= driver_name,
+		.pm	= MRST_PM_OPS,
+	}
+};
+
+module_platform_driver(vrtc_mrst_platform_driver);
+
+MODULE_AUTHOR("Jacob Pan; Feng Tang");
+MODULE_DESCRIPTION("Driver for Moorestown virtual RTC");
+MODULE_LICENSE("GPL");