[PATCH 1/2] rtc: rtc-lpc32xx: Introduce RTC driver for the LPC32XX SoC

[wellsk40@gmail.com (wellsk40 at gmail.com)]

From: Kevin Wells <wellsk40@gmail.com>

This patch contains the RTC driver for the built-in RTC in
the LPC32XX SoC.

Signed-off-by: Kevin Wells <wellsk40@gmail.com>
Signed-off-by: Durgesh Pattamatta <durgesh.pattamatta@nxp.com>
---
 drivers/rtc/rtc-lpc32xx.c |  391 +++++++++++++++++++++++++++++++++++++++++++++
 1 files changed, 391 insertions(+), 0 deletions(-)
 create mode 100644 drivers/rtc/rtc-lpc32xx.c

diff --git a/drivers/rtc/rtc-lpc32xx.c b/drivers/rtc/rtc-lpc32xx.c
new file mode 100644
index 0000000..7803c68
--- /dev/null
+++ b/drivers/rtc/rtc-lpc32xx.c
@@ -0,0 +1,391 @@
+/*
+ * 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 RTC_UCOUNT		0x00
+#define RTC_DCOUNT		0x04
+#define RTC_MATCH0		0x08
+#define RTC_MATCH1		0x0C
+#define RTC_CTRL		0x10
+#define RTC_INTSTAT		0x14
+#define RTC_KEY			0x18
+#define RTC_SRAM		0x80
+
+#define RTC_MATCH0_EN		(1 << 0)
+#define RTC_MATCH1_EN		(1 << 1)
+#define RTC_ONSW_MATCH0_EN	(1 << 2)
+#define RTC_ONSW_MATCH1_EN	(1 << 3)
+#define RTC_SW_RESET		(1 << 4)
+#define RTC_CNTR_DIS		(1 << 6)
+#define RTC_ONSW_FORCE_HIGH	(1 << 7)
+
+#define RTC_MATCH0_INT_STS	(1 << 0)
+#define RTC_MATCH1_INT_STS	(1 << 1)
+#define RTC_ONSW_INT_STS	(1 << 2)
+
+#define 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;
+	unsigned int irq;
+	int 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, 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, RTC_CTRL);
+	rtc_writel(rtc, RTC_CTRL, tmp | RTC_CNTR_DIS);
+	rtc_writel(rtc, RTC_UCOUNT, secs);
+	rtc_writel(rtc, RTC_DCOUNT, 0xFFFFFFFF - secs);
+	rtc_writel(rtc, RTC_CTRL, tmp &= ~RTC_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, RTC_MATCH0), &wkalrm->time);
+	wkalrm->enabled = rtc->alarm_enabled;
+
+	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_err(dev, "Failed to convert time: %d\n", ret);
+		return ret;
+	}
+
+	spin_lock_irq(&rtc->lock);
+
+	/* Disable alarm during update */
+	tmp = rtc_readl(rtc, RTC_CTRL);
+	rtc_writel(rtc, RTC_CTRL, tmp & ~RTC_MATCH0_EN);
+
+	rtc->alarm_enabled = wkalrm->enabled = 1;
+	if (wkalrm->enabled) {
+		rtc_writel(rtc, RTC_MATCH0, alarmsecs);
+		rtc_writel(rtc, RTC_INTSTAT, RTC_MATCH0_INT_STS);
+		rtc_writel(rtc, RTC_CTRL, tmp | RTC_MATCH0_EN);
+	}
+
+	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);
+	rtc->alarm_enabled = (int) enabled;
+	tmp = rtc_readl(rtc, RTC_CTRL);
+
+	if (enabled)
+		tmp |= RTC_MATCH0_EN;
+	else
+		tmp &= ~RTC_MATCH0_EN;
+
+	rtc_writel(rtc, 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 = (struct lpc32xx_rtc *) dev;
+
+	spin_lock(&rtc->lock);
+
+	/* Disable alarm interrupt */
+	rtc_writel(rtc, RTC_CTRL,
+		rtc_readl(rtc, RTC_CTRL) & ~RTC_MATCH0_EN);
+	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, RTC_MATCH0, 0xFFFFFFFF);
+	rtc_writel(rtc, RTC_INTSTAT, RTC_MATCH0_INT_STS);
+
+	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, *mem = NULL;
+	struct lpc32xx_rtc *rtc = NULL;
+	int rtcirq, retval;
+	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_err(&pdev->dev, "Can't get interrupt resource\n");
+		return -ENOENT;
+	}
+
+	rtc = kzalloc(sizeof(struct lpc32xx_rtc), GFP_KERNEL);
+	if (unlikely(!rtc)) {
+		dev_err(&pdev->dev, "Can't allocate memory\n");
+		return -ENOMEM;
+	}
+	rtc->irq = rtcirq;
+
+	mem = request_mem_region(res->start, resource_size(res), pdev->name);
+	if (!mem) {
+		dev_err(&pdev->dev, "RTC registers are not free\n");
+		retval = -EBUSY;
+		goto err_reqmem;
+	}
+
+	rtc->rtc_base = ioremap(res->start, res->end - res->start + 1);
+	if (!rtc->rtc_base) {
+		dev_err(&pdev->dev, "Can't map memory\n");
+		retval = -EIO;
+		goto err_noremap;
+	}
+
+	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.
+	 */
+	if (rtc_readl(rtc, RTC_KEY) == RTC_KEY_ONSW_LOADVAL) {
+		tmp = rtc_readl(rtc, RTC_CTRL);
+		tmp &= ~(RTC_SW_RESET | RTC_CNTR_DIS | RTC_MATCH0_EN |
+			RTC_MATCH1_EN |	RTC_ONSW_MATCH0_EN |
+			RTC_ONSW_MATCH1_EN | RTC_ONSW_FORCE_HIGH);
+		rtc_writel(rtc, RTC_CTRL, tmp);
+
+		/* Clear latched interrupt states */
+		rtc_writel(rtc, RTC_MATCH0, 0xFFFFFFFF);
+		rtc_writel(rtc, RTC_INTSTAT, RTC_MATCH0_INT_STS |
+			RTC_MATCH1_INT_STS | RTC_ONSW_INT_STS);
+
+		/* Write key value to RTC so it won't reload on reset */
+		rtc_writel(rtc, RTC_KEY, RTC_KEY_ONSW_LOADVAL);
+	} else if (rtc_readl(rtc, RTC_CTRL) & RTC_MATCH0_EN)
+		rtc->alarm_enabled = 1;
+
+	platform_set_drvdata(pdev, rtc);
+
+	device_init_wakeup(&pdev->dev, 1);
+	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");
+		retval = PTR_ERR(rtc->rtc);
+		goto err_noreg;
+	}
+
+	retval = request_irq(rtc->irq, lpc32xx_rtc_alarm_interrupt,
+		IRQF_DISABLED, "rtcalarm", rtc);
+	if (retval < 0) {
+		dev_err(&pdev->dev, "Can't request interrupt\n");
+		goto err_free_irq;
+	}
+
+	return 0;
+
+err_free_irq:
+	rtc_device_unregister(rtc->rtc);
+err_noreg:
+	iounmap(rtc->rtc_base);
+err_noremap:
+	release_resource(mem);
+err_reqmem:
+	kfree(rtc);
+
+	return retval;
+}
+
+static int __devexit lpc32xx_rtc_remove(struct platform_device *pdev)
+{
+	struct lpc32xx_rtc *rtc = platform_get_drvdata(pdev);
+
+	free_irq(rtc->irq, pdev);
+	rtc_device_unregister(rtc->rtc);
+	iounmap(rtc->rtc_base);
+	release_resource(dev_get_drvdata(&rtc->rtc->dev));
+	kfree(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 (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 (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, RTC_CTRL,
+		rtc_readl(rtc, RTC_CTRL) & ~RTC_MATCH0_EN);
+
+	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)
+		rtc_writel(rtc, RTC_CTRL,
+			rtc_readl(rtc, RTC_CTRL) | RTC_MATCH0_EN);
+
+	return 0;
+}
+
+#else
+#define lpc32xx_rtc_suspend NULL
+#define lpc32xx_rtc_resume NULL
+#define lpc32xx_rtc_freeze NULL
+#define lpc32xx_rtc_thaw NULL
+#endif
+
+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
+};
+
+static struct platform_driver lpc32xx_rtc_driver = {
+	.probe		= lpc32xx_rtc_probe,
+	.remove		= __devexit_p(lpc32xx_rtc_remove),
+	.driver = {
+		.name = RTC_NAME,
+		.pm = &lpc32xx_rtc_pm_ops,
+	},
+};
+
+static int __init lpc32xx_rtc_init(void)
+{
+	return platform_driver_register(&lpc32xx_rtc_driver);
+}
+
+static void __exit lpc32xx_rtc_exit(void)
+{
+	platform_driver_unregister(&lpc32xx_rtc_driver);
+}
+
+module_init(lpc32xx_rtc_init);
+module_exit(lpc32xx_rtc_exit);
+
+MODULE_AUTHOR("Kevin Wells <wellsk40@gmail.com");
+MODULE_DESCRIPTION("RTC driver for the LPC32xx SoC");
+MODULE_LICENSE("GPL");
-- 
1.7.1.1