rtc: rtc-lpc32xx: introduce RTC driver for the LPC32XX SoC

Add an RTC driver for the built-in RTC in the LPC32XX SoC.  This patch
includes updates from the initial review comments and updates from the v3
review.
Signed-off-by: Kevin Wells <wellsk40@gmail.com>
Signed-off-by: Durgesh Pattamatta <durgesh.pattamatta@nxp.com>
Reviewed-by: Wolfram Sang <w.sang@pengutronix.de>
Cc: Alessandro Zummo <a.zummo@towertech.it>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

drivers/rtc/Kconfig

@@ -952,4 +952,13 @@ config RTC_DRV_JZ4740
 	  This driver can also be buillt as a module. If so, the module
 	  will be called rtc-jz4740.
 
+config RTC_DRV_LPC32XX
+	depends on ARCH_LPC32XX
+	tristate "NXP LPC32XX RTC"
+	help
+	  This enables support for the NXP RTC in the LPC32XX
+
+	  This driver can also be buillt as a module. If so, the module
+	  will be called rtc-lpc32xx.
+
 endif # RTC_CLASS

drivers/rtc/Makefile

@@ -51,6 +51,7 @@ obj-$(CONFIG_RTC_DRV_IMXDI)	+= rtc-imxdi.o
 obj-$(CONFIG_RTC_DRV_ISL1208)	+= rtc-isl1208.o
 obj-$(CONFIG_RTC_DRV_ISL12022)	+= rtc-isl12022.o
 obj-$(CONFIG_RTC_DRV_JZ4740)	+= rtc-jz4740.o
+obj-$(CONFIG_RTC_DRV_LPC32XX)	+= rtc-lpc32xx.o
 obj-$(CONFIG_RTC_DRV_M41T80)	+= rtc-m41t80.o
 obj-$(CONFIG_RTC_DRV_M41T94)	+= rtc-m41t94.o
 obj-$(CONFIG_RTC_DRV_M48T35)	+= rtc-m48t35.o

drivers/rtc/rtc-lpc32xx.c

+/*
+ * Copyright (C) 2010 NXP Semiconductors
+ *
+ * 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; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with this program; if not, write to the Free Software Foundation, Inc.,
+ *  675 Mass Ave, Cambridge, MA 02139, USA.
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/platform_device.h>
+#include <linux/spinlock.h>
+#include <linux/rtc.h>
+#include <linux/slab.h>
+#include <linux/io.h>
+
+/*
+ * Clock and Power control register offsets
+ */
+#define LPC32XX_RTC_UCOUNT		0x00
+#define LPC32XX_RTC_DCOUNT		0x04
+#define LPC32XX_RTC_MATCH0		0x08
+#define LPC32XX_RTC_MATCH1		0x0C
+#define LPC32XX_RTC_CTRL		0x10
+#define LPC32XX_RTC_INTSTAT		0x14
+#define LPC32XX_RTC_KEY			0x18
+#define LPC32XX_RTC_SRAM		0x80
+
+#define LPC32XX_RTC_CTRL_MATCH0		(1 << 0)
+#define LPC32XX_RTC_CTRL_MATCH1		(1 << 1)
+#define LPC32XX_RTC_CTRL_ONSW_MATCH0	(1 << 2)
+#define LPC32XX_RTC_CTRL_ONSW_MATCH1	(1 << 3)
+#define LPC32XX_RTC_CTRL_SW_RESET	(1 << 4)
+#define LPC32XX_RTC_CTRL_CNTR_DIS	(1 << 6)
+#define LPC32XX_RTC_CTRL_ONSW_FORCE_HI	(1 << 7)
+
+#define LPC32XX_RTC_INTSTAT_MATCH0	(1 << 0)
+#define LPC32XX_RTC_INTSTAT_MATCH1	(1 << 1)
+#define LPC32XX_RTC_INTSTAT_ONSW	(1 << 2)
+
+#define LPC32XX_RTC_KEY_ONSW_LOADVAL	0xB5C13F27
+
+#define RTC_NAME "rtc-lpc32xx"
+
+#define rtc_readl(dev, reg) \
+	__raw_readl((dev)->rtc_base + (reg))
+#define rtc_writel(dev, reg, val) \
+	__raw_writel((val), (dev)->rtc_base + (reg))
+
+struct lpc32xx_rtc {
+	void __iomem *rtc_base;
+	int irq;
+	unsigned char alarm_enabled;
+	struct rtc_device *rtc;
+	spinlock_t lock;
+};
+
+static int lpc32xx_rtc_read_time(struct device *dev, struct rtc_time *time)
+{
+	unsigned long elapsed_sec;
+	struct lpc32xx_rtc *rtc = dev_get_drvdata(dev);
+
+	elapsed_sec = rtc_readl(rtc, LPC32XX_RTC_UCOUNT);
+	rtc_time_to_tm(elapsed_sec, time);
+
+	return rtc_valid_tm(time);
+}
+
+static int lpc32xx_rtc_set_mmss(struct device *dev, unsigned long secs)
+{
+	struct lpc32xx_rtc *rtc = dev_get_drvdata(dev);
+	u32 tmp;
+
+	spin_lock_irq(&rtc->lock);
+
+	/* RTC must be disabled during count update */
+	tmp = rtc_readl(rtc, LPC32XX_RTC_CTRL);
+	rtc_writel(rtc, LPC32XX_RTC_CTRL, tmp | LPC32XX_RTC_CTRL_CNTR_DIS);
+	rtc_writel(rtc, LPC32XX_RTC_UCOUNT, secs);
+	rtc_writel(rtc, LPC32XX_RTC_DCOUNT, 0xFFFFFFFF - secs);
+	rtc_writel(rtc, LPC32XX_RTC_CTRL, tmp &= ~LPC32XX_RTC_CTRL_CNTR_DIS);
+
+	spin_unlock_irq(&rtc->lock);
+
+	return 0;
+}
+
+static int lpc32xx_rtc_read_alarm(struct device *dev,
+	struct rtc_wkalrm *wkalrm)
+{
+	struct lpc32xx_rtc *rtc = dev_get_drvdata(dev);
+
+	rtc_time_to_tm(rtc_readl(rtc, LPC32XX_RTC_MATCH0), &wkalrm->time);
+	wkalrm->enabled = rtc->alarm_enabled;
+	wkalrm->pending = !!(rtc_readl(rtc, LPC32XX_RTC_INTSTAT) &
+		LPC32XX_RTC_INTSTAT_MATCH0);
+
+	return rtc_valid_tm(&wkalrm->time);
+}
+
+static int lpc32xx_rtc_set_alarm(struct device *dev,
+	struct rtc_wkalrm *wkalrm)
+{
+	struct lpc32xx_rtc *rtc = dev_get_drvdata(dev);
+	unsigned long alarmsecs;
+	u32 tmp;
+	int ret;
+
+	ret = rtc_tm_to_time(&wkalrm->time, &alarmsecs);
+	if (ret < 0) {
+		dev_warn(dev, "Failed to convert time: %d\n", ret);
+		return ret;
+	}
+
+	spin_lock_irq(&rtc->lock);
+
+	/* Disable alarm during update */
+	tmp = rtc_readl(rtc, LPC32XX_RTC_CTRL);
+	rtc_writel(rtc, LPC32XX_RTC_CTRL, tmp & ~LPC32XX_RTC_CTRL_MATCH0);
+
+	rtc_writel(rtc, LPC32XX_RTC_MATCH0, alarmsecs);
+
+	rtc->alarm_enabled = wkalrm->enabled;
+	if (wkalrm->enabled) {
+		rtc_writel(rtc, LPC32XX_RTC_INTSTAT,
+			   LPC32XX_RTC_INTSTAT_MATCH0);
+		rtc_writel(rtc, LPC32XX_RTC_CTRL, tmp |
+			   LPC32XX_RTC_CTRL_MATCH0);
+	}
+
+	spin_unlock_irq(&rtc->lock);
+
+	return 0;
+}
+
+static int lpc32xx_rtc_alarm_irq_enable(struct device *dev,
+	unsigned int enabled)
+{
+	struct lpc32xx_rtc *rtc = dev_get_drvdata(dev);
+	u32 tmp;
+
+	spin_lock_irq(&rtc->lock);
+	tmp = rtc_readl(rtc, LPC32XX_RTC_CTRL);
+
+	if (enabled) {
+		rtc->alarm_enabled = 1;
+		tmp |= LPC32XX_RTC_CTRL_MATCH0;
+	} else {
+		rtc->alarm_enabled = 0;
+		tmp &= ~LPC32XX_RTC_CTRL_MATCH0;
+	}
+
+	rtc_writel(rtc, LPC32XX_RTC_CTRL, tmp);
+	spin_unlock_irq(&rtc->lock);
+
+	return 0;
+}
+
+static irqreturn_t lpc32xx_rtc_alarm_interrupt(int irq, void *dev)
+{
+	struct lpc32xx_rtc *rtc = dev;
+
+	spin_lock(&rtc->lock);
+
+	/* Disable alarm interrupt */
+	rtc_writel(rtc, LPC32XX_RTC_CTRL,
+		rtc_readl(rtc, LPC32XX_RTC_CTRL) &
+			  ~LPC32XX_RTC_CTRL_MATCH0);
+	rtc->alarm_enabled = 0;
+
+	/*
+	 * Write a large value to the match value so the RTC won't
+	 * keep firing the match status
+	 */
+	rtc_writel(rtc, LPC32XX_RTC_MATCH0, 0xFFFFFFFF);
+	rtc_writel(rtc, LPC32XX_RTC_INTSTAT, LPC32XX_RTC_INTSTAT_MATCH0);
+
+	spin_unlock(&rtc->lock);
+
+	rtc_update_irq(rtc->rtc, 1, RTC_IRQF | RTC_AF);
+
+	return IRQ_HANDLED;
+}
+
+static const struct rtc_class_ops lpc32xx_rtc_ops = {
+	.read_time		= lpc32xx_rtc_read_time,
+	.set_mmss		= lpc32xx_rtc_set_mmss,
+	.read_alarm		= lpc32xx_rtc_read_alarm,
+	.set_alarm		= lpc32xx_rtc_set_alarm,
+	.alarm_irq_enable	= lpc32xx_rtc_alarm_irq_enable,
+};
+
+static int __devinit lpc32xx_rtc_probe(struct platform_device *pdev)
+{
+	struct resource *res;
+	struct lpc32xx_rtc *rtc;
+	resource_size_t size;
+	int rtcirq;
+	u32 tmp;
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	if (!res) {
+		dev_err(&pdev->dev, "Can't get memory resource\n");
+		return -ENOENT;
+	}
+
+	rtcirq = platform_get_irq(pdev, 0);
+	if (rtcirq < 0 || rtcirq >= NR_IRQS) {
+		dev_warn(&pdev->dev, "Can't get interrupt resource\n");
+		rtcirq = -1;
+	}
+
+	rtc = devm_kzalloc(&pdev->dev, sizeof(*rtc), GFP_KERNEL);
+	if (unlikely(!rtc)) {
+		dev_err(&pdev->dev, "Can't allocate memory\n");
+		return -ENOMEM;
+	}
+	rtc->irq = rtcirq;
+
+	size = resource_size(res);
+
+	if (!devm_request_mem_region(&pdev->dev, res->start, size,
+				     pdev->name)) {
+		dev_err(&pdev->dev, "RTC registers are not free\n");
+		return -EBUSY;
+	}
+
+	rtc->rtc_base = devm_ioremap(&pdev->dev, res->start, size);
+	if (!rtc->rtc_base) {
+		dev_err(&pdev->dev, "Can't map memory\n");
+		return -ENOMEM;
+	}
+
+	spin_lock_init(&rtc->lock);
+
+	/*
+	 * The RTC is on a seperate power domain and can keep it's state
+	 * across a chip power cycle. If the RTC has never been previously
+	 * setup, then set it up now for the first time.
+	 */
+	tmp = rtc_readl(rtc, LPC32XX_RTC_CTRL);
+	if (rtc_readl(rtc, LPC32XX_RTC_KEY) != LPC32XX_RTC_KEY_ONSW_LOADVAL) {
+		tmp &= ~(LPC32XX_RTC_CTRL_SW_RESET |
+			LPC32XX_RTC_CTRL_CNTR_DIS |
+			LPC32XX_RTC_CTRL_MATCH0 |
+			LPC32XX_RTC_CTRL_MATCH1 |
+			LPC32XX_RTC_CTRL_ONSW_MATCH0 |
+			LPC32XX_RTC_CTRL_ONSW_MATCH1 |
+			LPC32XX_RTC_CTRL_ONSW_FORCE_HI);
+		rtc_writel(rtc, LPC32XX_RTC_CTRL, tmp);
+
+		/* Clear latched interrupt states */
+		rtc_writel(rtc, LPC32XX_RTC_MATCH0, 0xFFFFFFFF);
+		rtc_writel(rtc, LPC32XX_RTC_INTSTAT,
+			   LPC32XX_RTC_INTSTAT_MATCH0 |
+			   LPC32XX_RTC_INTSTAT_MATCH1 |
+			   LPC32XX_RTC_INTSTAT_ONSW);
+
+		/* Write key value to RTC so it won't reload on reset */
+		rtc_writel(rtc, LPC32XX_RTC_KEY,
+			   LPC32XX_RTC_KEY_ONSW_LOADVAL);
+	} else {
+		rtc_writel(rtc, LPC32XX_RTC_CTRL,
+			   tmp & ~LPC32XX_RTC_CTRL_MATCH0);
+	}
+
+	platform_set_drvdata(pdev, rtc);
+
+	rtc->rtc = rtc_device_register(RTC_NAME, &pdev->dev, &lpc32xx_rtc_ops,
+		THIS_MODULE);
+	if (IS_ERR(rtc->rtc)) {
+		dev_err(&pdev->dev, "Can't get RTC\n");
+		platform_set_drvdata(pdev, NULL);
+		return PTR_ERR(rtc->rtc);
+	}
+
+	/*
+	 * IRQ is enabled after device registration in case alarm IRQ
+	 * is pending upon suspend exit.
+	 */
+	if (rtc->irq >= 0) {
+		if (devm_request_irq(&pdev->dev, rtc->irq,
+				     lpc32xx_rtc_alarm_interrupt,
+				     IRQF_DISABLED, pdev->name, rtc) < 0) {
+			dev_warn(&pdev->dev, "Can't request interrupt.\n");
+			rtc->irq = -1;
+		} else {
+			device_init_wakeup(&pdev->dev, 1);
+		}
+	}
+
+	return 0;
+}
+
+static int __devexit lpc32xx_rtc_remove(struct platform_device *pdev)
+{
+	struct lpc32xx_rtc *rtc = platform_get_drvdata(pdev);
+
+	if (rtc->irq >= 0)
+		device_init_wakeup(&pdev->dev, 0);
+
+	platform_set_drvdata(pdev, NULL);
+	rtc_device_unregister(rtc->rtc);
+
+	return 0;
+}
+
+#ifdef CONFIG_PM
+static int lpc32xx_rtc_suspend(struct device *dev)
+{
+	struct platform_device *pdev = to_platform_device(dev);
+	struct lpc32xx_rtc *rtc = platform_get_drvdata(pdev);
+
+	if (rtc->irq >= 0) {
+		if (device_may_wakeup(&pdev->dev))
+			enable_irq_wake(rtc->irq);
+		else
+			disable_irq_wake(rtc->irq);
+	}
+
+	return 0;
+}
+
+static int lpc32xx_rtc_resume(struct device *dev)
+{
+	struct platform_device *pdev = to_platform_device(dev);
+	struct lpc32xx_rtc *rtc = platform_get_drvdata(pdev);
+
+	if (rtc->irq >= 0 && device_may_wakeup(&pdev->dev))
+		disable_irq_wake(rtc->irq);
+
+	return 0;
+}
+
+/* Unconditionally disable the alarm */
+static int lpc32xx_rtc_freeze(struct device *dev)
+{
+	struct platform_device *pdev = to_platform_device(dev);
+	struct lpc32xx_rtc *rtc = platform_get_drvdata(pdev);
+
+	spin_lock_irq(&rtc->lock);
+
+	rtc_writel(rtc, LPC32XX_RTC_CTRL,
+		rtc_readl(rtc, LPC32XX_RTC_CTRL) &
+			  ~LPC32XX_RTC_CTRL_MATCH0);
+
+	spin_unlock_irq(&rtc->lock);
+
+	return 0;
+}
+
+static int lpc32xx_rtc_thaw(struct device *dev)
+{
+	struct platform_device *pdev = to_platform_device(dev);
+	struct lpc32xx_rtc *rtc = platform_get_drvdata(pdev);
+
+	if (rtc->alarm_enabled) {
+		spin_lock_irq(&rtc->lock);
+
+		rtc_writel(rtc, LPC32XX_RTC_CTRL,
+			   rtc_readl(rtc, LPC32XX_RTC_CTRL) |
+			   LPC32XX_RTC_CTRL_MATCH0);
+
+		spin_unlock_irq(&rtc->lock);
+	}
+
+	return 0;
+}
+
+static const struct dev_pm_ops lpc32xx_rtc_pm_ops = {
+	.suspend = lpc32xx_rtc_suspend,
+	.resume = lpc32xx_rtc_resume,
+	.freeze = lpc32xx_rtc_freeze,
+	.thaw = lpc32xx_rtc_thaw,
+	.restore = lpc32xx_rtc_resume
+};
+
+#define LPC32XX_RTC_PM_OPS (&lpc32xx_rtc_pm_ops)
+#else
+#define LPC32XX_RTC_PM_OPS NULL
+#endif
+
+static struct platform_driver lpc32xx_rtc_driver = {
+	.probe		= lpc32xx_rtc_probe,
+	.remove		= __devexit_p(lpc32xx_rtc_remove),
+	.driver = {
+		.name	= RTC_NAME,
+		.owner	= THIS_MODULE,
+		.pm	= LPC32XX_RTC_PM_OPS
+	},
+};
+
+static int __init lpc32xx_rtc_init(void)
+{
+	return platform_driver_register(&lpc32xx_rtc_driver);
+}
+module_init(lpc32xx_rtc_init);
+
+static void __exit lpc32xx_rtc_exit(void)
+{
+	platform_driver_unregister(&lpc32xx_rtc_driver);
+}
+module_exit(lpc32xx_rtc_exit);
+
+MODULE_AUTHOR("Kevin Wells <wellsk40@gmail.com");
+MODULE_DESCRIPTION("RTC driver for the LPC32xx SoC");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS("platform:rtc-lpc32xx");