ARM: sun4i/sun7i: RTC driver

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

Signed-off-by: Carlo Caione <carlo.caione@gmail.com>
Acked-by: Alessandro Zummo <a.zummo@towertech.it>
Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>

3 files changed, 531 insertions, 0 deletions

diff --git a/drivers/rtc/Kconfig b/drivers/rtc/Kconfig
index 007730222116..c2fa86c0abad 100644
--- a/drivers/rtc/Kconfig
+++ b/drivers/rtc/Kconfig
@@ -1104,6 +1104,13 @@ 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 27b4bd884066..63f3e9983a45 100644
--- a/drivers/rtc/Makefile
+++ b/drivers/rtc/Makefile
@@ -117,6 +117,7 @@ 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 000000000000..68a35284e5ad
--- /dev/null
+++ b/drivers/rtc/rtc-sunxi.c
@@ -0,0 +1,523 @@
+/*
+ * 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_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)
+
+/*
+ * The year parameter passed to the driver is usually an offset relative to
+ * the year 1900. This macro is used to convert this offset to another one
+ * relative to the minimum year allowed by the hardware.
+ */
+#define SUNXI_YEAR_OFF(x)                       ((x)->min - 1900)
+
+/*
+ * min and max year are arbitrary set considering the limited range of the
+ * hardware register field
+ */
+struct sunxi_rtc_data_year {
+        unsigned int min;               /* min year allowed */
+        unsigned int max;               /* max year allowed */
+        unsigned int mask;              /* mask for the year field */
+        unsigned char leap_shift;       /* bit shift to get the leap year */
+};
+
+static struct sunxi_rtc_data_year data_year_param[] = {
+        [0] = {
+                .min            = 2010,
+                .max            = 2073,
+                .mask           = 0x3f,
+                .leap_shift     = 22,
+        },
+        [1] = {
+                .min            = 1970,
+                .max            = 2225,
+                .mask           = 0xff,
+                .leap_shift     = 24,
+        },
+};
+
+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_mon -= 1;
+
+        /*
+         * switch from (data_year->min)-relative offset to
+         * a (1900)-relative one
+         */
+        alrm_tm->tm_year += SUNXI_YEAR_OFF(chip->data_year);
+
+        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;
+
+        /*
+         * read again in case it changes
+         */
+        do {
+                date = readl(chip->base + SUNXI_RTC_YMD);
+                time = readl(chip->base + SUNXI_RTC_HMS);
+        } while ((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);
+
+        rtc_tm->tm_mon  -= 1;
+
+        /*
+         * switch from (data_year->min)-relative offset to
+         * a (1900)-relative one
+         */
+        rtc_tm->tm_year += SUNXI_YEAR_OFF(chip->data_year);
+
+        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_wait(struct sunxi_rtc_dev *chip, int offset,
+                          unsigned int mask, unsigned int ms_timeout)
+{
+        const unsigned long timeout = jiffies + msecs_to_jiffies(ms_timeout);
+        u32 reg;
+
+        do {
+                reg = readl(chip->base + offset);
+                reg &= mask;
+
+                if (reg == mask)
+                        return 0;
+
+        } while (time_before(jiffies, timeout));
+
+        return -ETIMEDOUT;
+}
+
+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;
+
+        /*
+         * the input rtc_tm->tm_year is the offset relative to 1900. We use
+         * the SUNXI_YEAR_OFF macro to rebase it with respect to the min year
+         * allowed by the hardware
+         */
+
+        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 -= SUNXI_YEAR_OFF(chip->data_year);
+        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 RTC HH-MM-SS register, the
+         * SUNXI_LOSC_CTRL_RTC_HMS_ACC bit is set and it will not
+         * be cleared until the real writing operation is finished
+         */
+
+        if (sunxi_rtc_wait(chip, SUNXI_LOSC_CTRL,
+                                SUNXI_LOSC_CTRL_RTC_HMS_ACC, 50)) {
+                dev_err(dev, "Failed to set rtc time.\n");
+                return -1;
+        }
+
+        writel(date, chip->base + SUNXI_RTC_YMD);
+
+        /*
+         * After writing the RTC YY-MM-DD register, the
+         * SUNXI_LOSC_CTRL_RTC_YMD_ACC bit is set and it will not
+         * be cleared until the real writing operation is finished
+         */
+
+        if (sunxi_rtc_wait(chip, SUNXI_LOSC_CTRL,
+                                SUNXI_LOSC_CTRL_RTC_YMD_ACC, 50)) {
+                dev_err(dev, "Failed to set rtc time.\n");
+                return -1;
+        }
+
+        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");