[PATCH v3 1/2] ARM: sun4i/sun7i: RTC driver

[carlo.caione@gmail.com (Carlo Caione)]

This patch introduces the driver for the RTC in the Allwinner A10 and
A20 SoCs.

Signed-off-by: Carlo Caione <carlo.caione@gmail.com>
---
v1->v2:
- Patch split in two
- Fix coding style
- New driver description
- Rework macros
- Add comments
- Change while in for cycles

v2->v3
- Fix comments
- Rename alarm->alrm
- Fix comments style
- Remove useless newline
---
 drivers/rtc/Kconfig     |   7 +
 drivers/rtc/Makefile    |   1 +
 drivers/rtc/rtc-sunxi.c | 491 ++++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 499 insertions(+)
 create mode 100644 drivers/rtc/rtc-sunxi.c

diff --git a/drivers/rtc/Kconfig b/drivers/rtc/Kconfig
index 9654aa3..ef45e0b 100644
--- a/drivers/rtc/Kconfig
+++ b/drivers/rtc/Kconfig
@@ -1076,6 +1076,13 @@ config RTC_DRV_SUN4V
 	  If you say Y here you will get support for the Hypervisor
 	  based RTC on SUN4V systems.
 
+config RTC_DRV_SUNXI
+	tristate "Allwinner sun4i/sun7i RTC"
+	depends on ARCH_SUNXI
+	help
+	  If you say Y here you will get support for the RTC found on
+	  Allwinner A10/A20.
+
 config RTC_DRV_STARFIRE
 	bool "Starfire RTC"
 	depends on SPARC64
diff --git a/drivers/rtc/Makefile b/drivers/rtc/Makefile
index 2dff3d2..8b52b5a 100644
--- a/drivers/rtc/Makefile
+++ b/drivers/rtc/Makefile
@@ -115,6 +115,7 @@ obj-$(CONFIG_RTC_DRV_STARFIRE)	+= rtc-starfire.o
 obj-$(CONFIG_RTC_DRV_STK17TA8)	+= rtc-stk17ta8.o
 obj-$(CONFIG_RTC_DRV_STMP)	+= rtc-stmp3xxx.o
 obj-$(CONFIG_RTC_DRV_SUN4V)	+= rtc-sun4v.o
+obj-$(CONFIG_RTC_DRV_SUNXI)	+= rtc-sunxi.o
 obj-$(CONFIG_RTC_DRV_TEGRA)	+= rtc-tegra.o
 obj-$(CONFIG_RTC_DRV_TEST)	+= rtc-test.o
 obj-$(CONFIG_RTC_DRV_TILE)	+= rtc-tile.o
diff --git a/drivers/rtc/rtc-sunxi.c b/drivers/rtc/rtc-sunxi.c
new file mode 100644
index 0000000..89c331f
--- /dev/null
+++ b/drivers/rtc/rtc-sunxi.c
@@ -0,0 +1,491 @@
+/*
+ * An RTC driver for Allwinner A10/A20
+ *
+ * Copyright (c) 2013, Carlo Caione <carlo.caione@gmail.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; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+ * more details.
+ *
+ * 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.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ */
+
+#include <linux/delay.h>
+#include <linux/err.h>
+#include <linux/fs.h>
+#include <linux/init.h>
+#include <linux/interrupt.h>
+#include <linux/io.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/of_address.h>
+#include <linux/of_device.h>
+#include <linux/platform_device.h>
+#include <linux/rtc.h>
+#include <linux/types.h>
+
+#define SUNXI_LOSC_CTRL				0x0000
+#define SUNXI_LOSC_CTRL_RTC_HMS_ACC		BIT(8)
+#define SUNXI_LOSC_CTRL_RTC_YMD_ACC		BIT(7)
+
+#define SUNXI_RTC_YMD				0x0004
+
+#define SUNXI_RTC_HMS				0x0008
+
+#define SUNXI_ALRM_DHMS				0x000c
+
+#define SUNXI_ALRM_EN				0x0014
+#define SUNXI_ALRM_EN_CNT_EN			BIT(8)
+
+#define SUNXI_ALRM_IRQ_EN			0x0018
+#define SUNXI_ALRM_IRQ_EN_CNT_IRQ_EN		BIT(0)
+
+#define SUNXI_ALRM_IRQ_STA			0x001c
+#define SUNXI_ALRM_IRQ_STA_CNT_IRQ_PEND		BIT(0)
+
+#define SUNXI_LOSC_CTRL_RTC_ACC \
+	(SUNXI_LOSC_CTRL_RTC_HMS_ACC | SUNXI_LOSC_CTRL_RTC_YMD_ACC)
+
+#define SUNXI_MASK_DH				0x0000001f
+#define SUNXI_MASK_SM				0x0000003f
+#define SUNXI_MASK_M				0x0000000f
+#define SUNXI_MASK_LY				0x00000001
+#define SUNXI_MASK_D				0x00000ffe
+#define SUNXI_MASK_M				0x0000000f
+
+#define SUNXI_GET(x, mask, shift)		(((x) & ((mask) << (shift))) \
+							>> (shift))
+
+#define SUNXI_SET(x, mask, shift)		(((x) & (mask)) << (shift))
+
+/* Get date values */
+#define SUNXI_DATE_GET_DAY_VALUE(x)		SUNXI_GET(x, SUNXI_MASK_DH, 0)
+#define SUNXI_DATE_GET_MON_VALUE(x)		SUNXI_GET(x, SUNXI_MASK_M, 8)
+#define SUNXI_DATE_GET_YEAR_VALUE(x, mask)	SUNXI_GET(x, mask, 16)
+
+/* Get time values */
+#define SUNXI_TIME_GET_SEC_VALUE(x)		SUNXI_GET(x, SUNXI_MASK_SM, 0)
+#define SUNXI_TIME_GET_MIN_VALUE(x)		SUNXI_GET(x, SUNXI_MASK_SM, 8)
+#define SUNXI_TIME_GET_HOUR_VALUE(x)		SUNXI_GET(x, SUNXI_MASK_DH, 16)
+
+/* Get alarm values */
+#define SUNXI_ALRM_GET_SEC_VALUE(x)		SUNXI_GET(x, SUNXI_MASK_SM, 0)
+#define SUNXI_ALRM_GET_MIN_VALUE(x)		SUNXI_GET(x, SUNXI_MASK_SM, 8)
+#define SUNXI_ALRM_GET_HOUR_VALUE(x)		SUNXI_GET(x, SUNXI_MASK_DH, 16)
+
+/* Set date values */
+#define SUNXI_DATE_SET_DAY_VALUE(x)		SUNXI_DATE_GET_DAY_VALUE(x)
+#define SUNXI_DATE_SET_MON_VALUE(x)		SUNXI_SET(x, SUNXI_MASK_M, 8)
+#define SUNXI_DATE_SET_YEAR_VALUE(x, mask)	SUNXI_SET(x, mask, 16)
+#define SUNXI_LEAP_SET_VALUE(x, shift)		SUNXI_SET(x, SUNXI_MASK_LY, shift)
+
+/* Set time values */
+#define SUNXI_TIME_SET_SEC_VALUE(x)		SUNXI_TIME_GET_SEC_VALUE(x)
+#define SUNXI_TIME_SET_MIN_VALUE(x)		SUNXI_SET(x, SUNXI_MASK_SM, 8)
+#define SUNXI_TIME_SET_HOUR_VALUE(x)		SUNXI_SET(x, SUNXI_MASK_DH, 16)
+
+/* set alarm values */
+#define SUNXI_ALRM_SET_SEC_VALUE(x)		SUNXI_ALRM_GET_SEC_VALUE(x)
+#define SUNXI_ALRM_SET_MIN_VALUE(x)		SUNXI_SET(x, SUNXI_MASK_SM, 8)
+#define SUNXI_ALRM_SET_HOUR_VALUE(x)		SUNXI_SET(x, SUNXI_MASK_DH, 16)
+#define SUNXI_ALRM_SET_DAY_VALUE(x)		SUNXI_SET(x, SUNXI_MASK_D, 21)
+
+/* time unit conversions */
+#define SEC_IN_MIN				60
+#define SEC_IN_HOUR				(60 * SEC_IN_MIN)
+#define SEC_IN_DAY				(24 * SEC_IN_HOUR)
+
+struct sunxi_rtc_data_year {
+	unsigned int min;		/* min year allowed */
+	unsigned int max;		/* max year allowed */
+	unsigned int off;		/* year offset to get the current year */
+	unsigned int mask;
+	unsigned char leap_shift;	/* bit shift to get the leap year */
+};
+
+static struct sunxi_rtc_data_year data_year_param[] = {
+	[0] = {
+		.min		= 1970,
+		.max		= 2100,
+		.off		= 0,
+		.mask		= 0x000000ff,
+		.leap_shift	= 24,
+	},
+	[1] = {
+		.min		= 2010,
+		.max		= 2073,
+		.off		= 110,
+		.mask		= 0x0000003f,
+		.leap_shift	= 22,
+	},
+};
+
+struct sunxi_rtc_dev {
+	struct rtc_device *rtc;
+	struct device *dev;
+	struct sunxi_rtc_data_year *data_year;
+	void __iomem *base;
+	int irq;
+};
+
+static irqreturn_t sunxi_rtc_alarmirq(int irq, void *id)
+{
+	struct sunxi_rtc_dev *chip = (struct sunxi_rtc_dev *) id;
+	u32 val;
+
+	val = readl(chip->base + SUNXI_ALRM_IRQ_STA);
+
+	if (val & SUNXI_ALRM_IRQ_STA_CNT_IRQ_PEND) {
+		val |= SUNXI_ALRM_IRQ_STA_CNT_IRQ_PEND;
+		writel(val, chip->base + SUNXI_ALRM_IRQ_STA);
+
+		rtc_update_irq(chip->rtc, 1, RTC_AF | RTC_IRQF);
+
+		return IRQ_HANDLED;
+	}
+
+	return IRQ_NONE;
+}
+
+static void sunxi_rtc_setaie(int to, struct sunxi_rtc_dev *chip)
+{
+	u32 alrm_val = 0;
+	u32 alrm_irq_val = 0;
+
+	if (to) {
+		alrm_val = readl(chip->base + SUNXI_ALRM_EN);
+		alrm_val |= SUNXI_ALRM_EN_CNT_EN;
+
+		alrm_irq_val = readl(chip->base + SUNXI_ALRM_IRQ_EN);
+		alrm_irq_val |= SUNXI_ALRM_IRQ_EN_CNT_IRQ_EN;
+	} else {
+		writel(SUNXI_ALRM_IRQ_STA_CNT_IRQ_PEND,
+				chip->base + SUNXI_ALRM_IRQ_STA);
+	}
+
+	writel(alrm_val, chip->base + SUNXI_ALRM_EN);
+	writel(alrm_irq_val, chip->base + SUNXI_ALRM_IRQ_EN);
+}
+
+static int sunxi_rtc_getalarm(struct device *dev, struct rtc_wkalrm *wkalrm)
+{
+	struct sunxi_rtc_dev *chip = dev_get_drvdata(dev);
+	struct rtc_time *alrm_tm = &wkalrm->time;
+	u32 alrm;
+	u32 alrm_en;
+	u32 date;
+
+	alrm = readl(chip->base + SUNXI_ALRM_DHMS);
+	date = readl(chip->base + SUNXI_RTC_YMD);
+
+	alrm_tm->tm_sec = SUNXI_ALRM_GET_SEC_VALUE(alrm);
+	alrm_tm->tm_min = SUNXI_ALRM_GET_MIN_VALUE(alrm);
+	alrm_tm->tm_hour = SUNXI_ALRM_GET_HOUR_VALUE(alrm);
+
+	alrm_tm->tm_mday = SUNXI_DATE_GET_DAY_VALUE(date);
+	alrm_tm->tm_mon = SUNXI_DATE_GET_MON_VALUE(date);
+	alrm_tm->tm_year = SUNXI_DATE_GET_YEAR_VALUE(date,
+			chip->data_year->mask);
+
+	alrm_tm->tm_year += chip->data_year->off;
+	alrm_tm->tm_mon -= 1;
+
+	alrm_en = readl(chip->base + SUNXI_ALRM_IRQ_EN);
+	if (alrm_en & SUNXI_ALRM_EN_CNT_EN)
+		wkalrm->enabled = 1;
+
+	return 0;
+}
+
+static int sunxi_rtc_gettime(struct device *dev, struct rtc_time *rtc_tm)
+{
+	struct sunxi_rtc_dev *chip = dev_get_drvdata(dev);
+	u32 date, time;
+	int t;
+
+	/*
+	 * read again if the system was mid-updated
+	 */
+	for (t = 0; t < 2; t++) {
+		date = readl(chip->base + SUNXI_RTC_YMD);
+		time = readl(chip->base + SUNXI_RTC_HMS);
+
+		rtc_tm->tm_sec  = SUNXI_TIME_GET_SEC_VALUE(time);
+		rtc_tm->tm_min  = SUNXI_TIME_GET_MIN_VALUE(time);
+		rtc_tm->tm_hour = SUNXI_TIME_GET_HOUR_VALUE(time);
+
+		rtc_tm->tm_mday = SUNXI_DATE_GET_DAY_VALUE(date);
+		rtc_tm->tm_mon  = SUNXI_DATE_GET_MON_VALUE(date);
+		rtc_tm->tm_year = SUNXI_DATE_GET_YEAR_VALUE(date,
+				chip->data_year->mask);
+
+		if (rtc_tm->tm_sec == 0)
+			msleep(500);
+		else
+			break;
+	}
+
+	rtc_tm->tm_year += chip->data_year->off;
+	rtc_tm->tm_mon  -= 1;
+
+	return rtc_valid_tm(rtc_tm);
+}
+
+static int sunxi_rtc_setalarm(struct device *dev, struct rtc_wkalrm *wkalrm)
+{
+	struct sunxi_rtc_dev *chip = dev_get_drvdata(dev);
+	struct rtc_time *alrm_tm = &wkalrm->time;
+	struct rtc_time tm_now;
+	u32 alrm = 0;
+	unsigned long time_now = 0;
+	unsigned long time_set = 0;
+	unsigned long time_gap = 0;
+	unsigned long time_gap_day = 0;
+	unsigned long time_gap_hour = 0;
+	unsigned long time_gap_min = 0;
+	int ret = 0;
+
+	ret = sunxi_rtc_gettime(dev, &tm_now);
+	if (ret < 0) {
+		dev_err(dev, "Error in getting time\n");
+		return -EINVAL;
+	}
+
+	rtc_tm_to_time(alrm_tm, &time_set);
+	rtc_tm_to_time(&tm_now, &time_now);
+	if (time_set <= time_now) {
+		dev_err(dev, "Date to set in the past\n");
+		return -EINVAL;
+	}
+
+	time_gap = time_set - time_now;
+	time_gap_day = time_gap / SEC_IN_DAY;
+	time_gap -= time_gap_day * SEC_IN_DAY;
+	time_gap_hour = time_gap / SEC_IN_HOUR;
+	time_gap -= time_gap_hour * SEC_IN_HOUR;
+	time_gap_min = time_gap / SEC_IN_MIN;
+	time_gap -= time_gap_min * SEC_IN_MIN;
+
+	if (time_gap_day > 255) {
+		dev_err(dev, "Day must be in the range 0 - 255\n");
+		return -EINVAL;
+	}
+
+	sunxi_rtc_setaie(0, chip);
+	writel(0, chip->base + SUNXI_ALRM_DHMS);
+	usleep_range(100, 300);
+
+	alrm = SUNXI_ALRM_SET_SEC_VALUE(time_gap) |
+		SUNXI_ALRM_SET_MIN_VALUE(time_gap_min) |
+		SUNXI_ALRM_SET_HOUR_VALUE(time_gap_hour) |
+		SUNXI_ALRM_SET_DAY_VALUE(time_gap_day);
+	writel(alrm, chip->base + SUNXI_ALRM_DHMS);
+
+	writel(0, chip->base + SUNXI_ALRM_IRQ_EN);
+	writel(SUNXI_ALRM_IRQ_EN_CNT_IRQ_EN, chip->base + SUNXI_ALRM_IRQ_EN);
+
+	sunxi_rtc_setaie(wkalrm->enabled, chip);
+
+	return 0;
+}
+
+static int sunxi_rtc_settime(struct device *dev, struct rtc_time *rtc_tm)
+{
+	struct sunxi_rtc_dev *chip = dev_get_drvdata(dev);
+	u32 date = 0;
+	u32 time = 0;
+	int year;
+	int t;
+
+	year = rtc_tm->tm_year + 1900;
+	if (year < chip->data_year->min || year > chip->data_year->max) {
+		dev_err(dev, "rtc only supports year in range %d - %d\n",
+				chip->data_year->min, chip->data_year->max);
+		return -EINVAL;
+	}
+
+	rtc_tm->tm_year -= chip->data_year->off;
+	rtc_tm->tm_mon += 1;
+
+	date = SUNXI_DATE_SET_DAY_VALUE(rtc_tm->tm_mday) |
+		SUNXI_DATE_SET_MON_VALUE(rtc_tm->tm_mon)  |
+		SUNXI_DATE_SET_YEAR_VALUE(rtc_tm->tm_year,
+				chip->data_year->mask);
+
+	if (is_leap_year(year))
+		date |= SUNXI_LEAP_SET_VALUE(1, chip->data_year->leap_shift);
+
+	time = SUNXI_TIME_SET_SEC_VALUE(rtc_tm->tm_sec)  |
+		SUNXI_TIME_SET_MIN_VALUE(rtc_tm->tm_min)  |
+		SUNXI_TIME_SET_HOUR_VALUE(rtc_tm->tm_hour);
+
+	writel(0, chip->base + SUNXI_RTC_HMS);
+	writel(0, chip->base + SUNXI_RTC_YMD);
+
+	writel(time, chip->base + SUNXI_RTC_HMS);
+
+	/*
+	 * After writing the RCT HH-MM-SS register, the
+	 * SUNXI_LOSC_CTRL_RTC_HMS_ACC bit is set and it will be cleared until
+	 * the real writing operation is finished
+	 */
+	for (t = 0; t < 3; t++) {
+		if ((readl(chip->base + SUNXI_LOSC_CTRL) &
+			SUNXI_LOSC_CTRL_RTC_HMS_ACC) && --t)
+			break;
+		else
+			msleep(50);
+	}
+	if (t == 0) {
+		dev_err(dev, "Failed to set rtc time.\n");
+		return -1;
+	}
+
+	writel(date, chip->base + SUNXI_RTC_YMD);
+
+	/*
+	 * After writing the RCT YY-MM-DD register, the
+	 * SUNXI_LOSC_CTRL_RTC_YMD_ACC bit is set and it will be cleared until
+	 * the real writing operation is finished
+	 */
+	for (t = 0; t < 3; t++) {
+		if ((readl(chip->base + SUNXI_LOSC_CTRL) &
+			SUNXI_LOSC_CTRL_RTC_YMD_ACC) && --t)
+			break;
+		else
+			msleep(50);
+	}
+	if (t == 0) {
+		dev_err(dev, "Failed to set rtc date.\n");
+		return -1;
+	}
+
+	/*
+	 * wait about 70us to make sure the the time is really written into
+	 * target
+	 */
+	usleep_range(70, 100);
+
+	return 0;
+}
+
+static int sunxi_rtc_alarm_irq_enable(struct device *dev, unsigned int enabled)
+{
+	struct sunxi_rtc_dev *chip = dev_get_drvdata(dev);
+
+	if (!enabled)
+		sunxi_rtc_setaie(enabled, chip);
+
+	return 0;
+}
+
+static const struct rtc_class_ops sunxi_rtc_ops = {
+	.read_time		= sunxi_rtc_gettime,
+	.set_time		= sunxi_rtc_settime,
+	.read_alarm		= sunxi_rtc_getalarm,
+	.set_alarm		= sunxi_rtc_setalarm,
+	.alarm_irq_enable	= sunxi_rtc_alarm_irq_enable
+};
+
+static const struct of_device_id sunxi_rtc_dt_ids[] = {
+	{ .compatible = "allwinner,sun4i-rtc", .data = &data_year_param[0] },
+	{ .compatible = "allwinner,sun7i-a20-rtc", .data = &data_year_param[1] },
+	{ /* sentinel */ },
+};
+MODULE_DEVICE_TABLE(of, sunxi_rtc_dt_ids);
+
+static int sunxi_rtc_probe(struct platform_device *pdev)
+{
+	struct sunxi_rtc_dev *chip;
+	struct resource *res;
+	const struct of_device_id *of_id;
+	int ret;
+
+	chip = devm_kzalloc(&pdev->dev, sizeof(*chip), GFP_KERNEL);
+	if (!chip)
+		return -ENOMEM;
+
+	platform_set_drvdata(pdev, chip);
+	chip->dev = &pdev->dev;
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	chip->base = devm_ioremap_resource(&pdev->dev, res);
+	if (IS_ERR(chip->base))
+		return PTR_ERR(chip->base);
+
+	chip->irq = platform_get_irq(pdev, 0);
+	if (chip->irq < 0) {
+		dev_err(&pdev->dev, "No IRQ resource\n");
+		return chip->irq;
+	}
+	ret = devm_request_irq(&pdev->dev, chip->irq, sunxi_rtc_alarmirq,
+			0, dev_name(&pdev->dev), chip);
+	if (ret) {
+		dev_err(&pdev->dev, "Could not request IRQ\n");
+		return ret;
+	}
+
+	of_id = of_match_device(sunxi_rtc_dt_ids, &pdev->dev);
+	if (!of_id) {
+		dev_err(&pdev->dev, "Unable to setup RTC data\n");
+		return -ENODEV;
+	}
+	chip->data_year = (struct sunxi_rtc_data_year *) of_id->data;
+
+	/* clear the alarm count value */
+	writel(0, chip->base + SUNXI_ALRM_DHMS);
+
+	/* disable alarm, not generate irq pending */
+	writel(0, chip->base + SUNXI_ALRM_EN);
+
+	/* disable alarm week/cnt irq, unset to cpu */
+	writel(0, chip->base + SUNXI_ALRM_IRQ_EN);
+
+	/* clear alarm week/cnt irq pending */
+	writel(SUNXI_ALRM_IRQ_STA_CNT_IRQ_PEND, chip->base + SUNXI_ALRM_IRQ_STA);
+
+	chip->rtc = rtc_device_register("rtc-sunxi", &pdev->dev,
+			&sunxi_rtc_ops, THIS_MODULE);
+	if (IS_ERR(chip->rtc)) {
+		dev_err(&pdev->dev, "unable to register device\n");
+		return PTR_ERR(chip->rtc);
+	}
+
+	dev_info(&pdev->dev, "RTC enabled\n");
+
+	return 0;
+}
+
+static int sunxi_rtc_remove(struct platform_device *pdev)
+{
+	struct sunxi_rtc_dev *chip = platform_get_drvdata(pdev);
+
+	rtc_device_unregister(chip->rtc);
+
+	return 0;
+}
+
+static struct platform_driver sunxi_rtc_driver = {
+	.probe		= sunxi_rtc_probe,
+	.remove		= sunxi_rtc_remove,
+	.driver		= {
+		.name		= "sunxi-rtc",
+		.owner		= THIS_MODULE,
+		.of_match_table = sunxi_rtc_dt_ids,
+	},
+};
+
+module_platform_driver(sunxi_rtc_driver);
+
+MODULE_DESCRIPTION("sunxi RTC driver");
+MODULE_AUTHOR("Carlo Caione <carlo.caione@gmail.com>");
+MODULE_LICENSE("GPL");
-- 
1.8.4.2