rtc: AB8500 RTC driver

Add a driver for the RTC on the AB8500 power management chip.  This is a
client of the AB8500 MFD driver.

Signed-off-by: Virupax Sadashivpetimath <virupax.sadashivpetimath@stericsson.com>
Signed-off-by: Rabin Vincent <rabin.vincent@stericsson.com>
Acked-by: Linus Walleij <linus.walleij@stericsson.com>
Acked-by: Srinidhi Kasagar <srinidhi.kasagar@stericsson.com>
Cc: Alessandro Zummo <a.zummo@towertech.it>
Cc: Samuel Ortiz <sameo@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

3 files changed, 371 insertions, 0 deletions

diff --git a/drivers/rtc/Kconfig b/drivers/rtc/Kconfig
index f1598324344c..10ba12c8c5e0 100644
--- a/drivers/rtc/Kconfig
+++ b/drivers/rtc/Kconfig
@@ -611,6 +611,13 @@ config RTC_DRV_AB3100
           Select this to enable the ST-Ericsson AB3100 Mixed Signal IC RTC
           support. This chip contains a battery- and capacitor-backed RTC.
 
+config RTC_DRV_AB8500
+        tristate "ST-Ericsson AB8500 RTC"
+        depends on AB8500_CORE
+        help
+          Select this to enable the ST-Ericsson AB8500 power management IC RTC
+          support. This chip contains a battery- and capacitor-backed RTC.
+
 config RTC_DRV_NUC900
         tristate "NUC910/NUC920 RTC driver"
         depends on RTC_CLASS && ARCH_W90X900
diff --git a/drivers/rtc/Makefile b/drivers/rtc/Makefile
index 245311a1348f..5adbba7cf89c 100644
--- a/drivers/rtc/Makefile
+++ b/drivers/rtc/Makefile
@@ -18,6 +18,7 @@ rtc-core-$(CONFIG_RTC_INTF_SYSFS) += rtc-sysfs.o
 # Keep the list ordered.
 
 obj-$(CONFIG_RTC_DRV_AB3100)    += rtc-ab3100.o
+obj-$(CONFIG_RTC_DRV_AB8500)    += rtc-ab8500.o
 obj-$(CONFIG_RTC_DRV_AT32AP700X)+= rtc-at32ap700x.o
 obj-$(CONFIG_RTC_DRV_AT91RM9200)+= rtc-at91rm9200.o
 obj-$(CONFIG_RTC_DRV_AT91SAM9)  += rtc-at91sam9.o
diff --git a/drivers/rtc/rtc-ab8500.c b/drivers/rtc/rtc-ab8500.c
new file mode 100644
index 000000000000..2fda03125e55
--- /dev/null
+++ b/drivers/rtc/rtc-ab8500.c
@@ -0,0 +1,363 @@
+/*
+ * Copyright (C) ST-Ericsson SA 2010
+ *
+ * License terms: GNU General Public License (GPL) version 2
+ * Author: Virupax Sadashivpetimath <virupax.sadashivpetimath@stericsson.com>
+ *
+ * RTC clock driver for the RTC part of the AB8500 Power management chip.
+ * Based on RTC clock driver for the AB3100 Analog Baseband Chip by
+ * Linus Walleij <linus.walleij@stericsson.com>
+ */
+
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <linux/init.h>
+#include <linux/platform_device.h>
+#include <linux/rtc.h>
+#include <linux/mfd/ab8500.h>
+#include <linux/delay.h>
+
+#define AB8500_RTC_SOFF_STAT_REG        0x0F00
+#define AB8500_RTC_CC_CONF_REG          0x0F01
+#define AB8500_RTC_READ_REQ_REG         0x0F02
+#define AB8500_RTC_WATCH_TSECMID_REG    0x0F03
+#define AB8500_RTC_WATCH_TSECHI_REG     0x0F04
+#define AB8500_RTC_WATCH_TMIN_LOW_REG   0x0F05
+#define AB8500_RTC_WATCH_TMIN_MID_REG   0x0F06
+#define AB8500_RTC_WATCH_TMIN_HI_REG    0x0F07
+#define AB8500_RTC_ALRM_MIN_LOW_REG     0x0F08
+#define AB8500_RTC_ALRM_MIN_MID_REG     0x0F09
+#define AB8500_RTC_ALRM_MIN_HI_REG      0x0F0A
+#define AB8500_RTC_STAT_REG             0x0F0B
+#define AB8500_RTC_BKUP_CHG_REG         0x0F0C
+#define AB8500_RTC_FORCE_BKUP_REG       0x0F0D
+#define AB8500_RTC_CALIB_REG            0x0F0E
+#define AB8500_RTC_SWITCH_STAT_REG      0x0F0F
+#define AB8500_REV_REG                  0x1080
+
+/* RtcReadRequest bits */
+#define RTC_READ_REQUEST                0x01
+#define RTC_WRITE_REQUEST               0x02
+
+/* RtcCtrl bits */
+#define RTC_ALARM_ENA                   0x04
+#define RTC_STATUS_DATA                 0x01
+
+#define COUNTS_PER_SEC                  (0xF000 / 60)
+#define AB8500_RTC_EPOCH                2000
+
+static const unsigned long ab8500_rtc_time_regs[] = {
+        AB8500_RTC_WATCH_TMIN_HI_REG, AB8500_RTC_WATCH_TMIN_MID_REG,
+        AB8500_RTC_WATCH_TMIN_LOW_REG, AB8500_RTC_WATCH_TSECHI_REG,
+        AB8500_RTC_WATCH_TSECMID_REG
+};
+
+static const unsigned long ab8500_rtc_alarm_regs[] = {
+        AB8500_RTC_ALRM_MIN_HI_REG, AB8500_RTC_ALRM_MIN_MID_REG,
+        AB8500_RTC_ALRM_MIN_LOW_REG
+};
+
+/* Calculate the seconds from 1970 to 01-01-2000 00:00:00 */
+static unsigned long get_elapsed_seconds(int year)
+{
+        unsigned long secs;
+        struct rtc_time tm = {
+                .tm_year = year - 1900,
+                .tm_mday = 1,
+        };
+
+        /*
+         * This function calculates secs from 1970 and not from
+         * 1900, even if we supply the offset from year 1900.
+         */
+        rtc_tm_to_time(&tm, &secs);
+        return secs;
+}
+
+static int ab8500_rtc_read_time(struct device *dev, struct rtc_time *tm)
+{
+        struct ab8500 *ab8500 = dev_get_drvdata(dev->parent);
+        unsigned long timeout = jiffies + HZ;
+        int retval, i;
+        unsigned long mins, secs;
+        unsigned char buf[ARRAY_SIZE(ab8500_rtc_time_regs)];
+
+        /* Request a data read */
+        retval = ab8500_write(ab8500, AB8500_RTC_READ_REQ_REG,
+                              RTC_READ_REQUEST);
+        if (retval < 0)
+                return retval;
+
+        /* Early AB8500 chips will not clear the rtc read request bit */
+        if (ab8500->revision == 0) {
+                msleep(1);
+        } else {
+                /* Wait for some cycles after enabling the rtc read in ab8500 */
+                while (time_before(jiffies, timeout)) {
+                        retval = ab8500_read(ab8500, AB8500_RTC_READ_REQ_REG);
+                        if (retval < 0)
+                                return retval;
+
+                        if (!(retval & RTC_READ_REQUEST))
+                                break;
+
+                        msleep(1);
+                }
+        }
+
+        /* Read the Watchtime registers */
+        for (i = 0; i < ARRAY_SIZE(ab8500_rtc_time_regs); i++) {
+                retval = ab8500_read(ab8500, ab8500_rtc_time_regs[i]);
+                if (retval < 0)
+                        return retval;
+                buf[i] = retval;
+        }
+
+        mins = (buf[0] << 16) | (buf[1] << 8) | buf[2];
+
+        secs =  (buf[3] << 8) | buf[4];
+        secs =  secs / COUNTS_PER_SEC;
+        secs =  secs + (mins * 60);
+
+        /* Add back the initially subtracted number of seconds */
+        secs += get_elapsed_seconds(AB8500_RTC_EPOCH);
+
+        rtc_time_to_tm(secs, tm);
+        return rtc_valid_tm(tm);
+}
+
+static int ab8500_rtc_set_time(struct device *dev, struct rtc_time *tm)
+{
+        struct ab8500 *ab8500 = dev_get_drvdata(dev->parent);
+        int retval, i;
+        unsigned char buf[ARRAY_SIZE(ab8500_rtc_time_regs)];
+        unsigned long no_secs, no_mins, secs = 0;
+
+        if (tm->tm_year < (AB8500_RTC_EPOCH - 1900)) {
+                dev_dbg(dev, "year should be equal to or greater than %d\n",
+                                AB8500_RTC_EPOCH);
+                return -EINVAL;
+        }
+
+        /* Get the number of seconds since 1970 */
+        rtc_tm_to_time(tm, &secs);
+
+        /*
+         * Convert it to the number of seconds since 01-01-2000 00:00:00, since
+         * we only have a small counter in the RTC.
+         */
+        secs -= get_elapsed_seconds(AB8500_RTC_EPOCH);
+
+        no_mins = secs / 60;
+
+        no_secs = secs % 60;
+        /* Make the seconds count as per the RTC resolution */
+        no_secs = no_secs * COUNTS_PER_SEC;
+
+        buf[4] = no_secs & 0xFF;
+        buf[3] = (no_secs >> 8) & 0xFF;
+
+        buf[2] = no_mins & 0xFF;
+        buf[1] = (no_mins >> 8) & 0xFF;
+        buf[0] = (no_mins >> 16) & 0xFF;
+
+        for (i = 0; i < ARRAY_SIZE(ab8500_rtc_time_regs); i++) {
+                retval = ab8500_write(ab8500, ab8500_rtc_time_regs[i], buf[i]);
+                if (retval < 0)
+                        return retval;
+        }
+
+        /* Request a data write */
+        return ab8500_write(ab8500, AB8500_RTC_READ_REQ_REG, RTC_WRITE_REQUEST);
+}
+
+static int ab8500_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alarm)
+{
+        struct ab8500 *ab8500 = dev_get_drvdata(dev->parent);
+        int retval, i;
+        int rtc_ctrl;
+        unsigned char buf[ARRAY_SIZE(ab8500_rtc_alarm_regs)];
+        unsigned long secs, mins;
+
+        /* Check if the alarm is enabled or not */
+        rtc_ctrl = ab8500_read(ab8500, AB8500_RTC_STAT_REG);
+        if (rtc_ctrl < 0)
+                return rtc_ctrl;
+
+        if (rtc_ctrl & RTC_ALARM_ENA)
+                alarm->enabled = 1;
+        else
+                alarm->enabled = 0;
+
+        alarm->pending = 0;
+
+        for (i = 0; i < ARRAY_SIZE(ab8500_rtc_alarm_regs); i++) {
+                retval = ab8500_read(ab8500, ab8500_rtc_alarm_regs[i]);
+                if (retval < 0)
+                        return retval;
+                buf[i] = retval;
+        }
+
+        mins = (buf[0] << 16) | (buf[1] << 8) | (buf[2]);
+        secs = mins * 60;
+
+        /* Add back the initially subtracted number of seconds */
+        secs += get_elapsed_seconds(AB8500_RTC_EPOCH);
+
+        rtc_time_to_tm(secs, &alarm->time);
+
+        return rtc_valid_tm(&alarm->time);
+}
+
+static int ab8500_rtc_irq_enable(struct device *dev, unsigned int enabled)
+{
+        struct ab8500 *ab8500 = dev_get_drvdata(dev->parent);
+
+        return ab8500_set_bits(ab8500, AB8500_RTC_STAT_REG, RTC_ALARM_ENA,
+                               enabled ? RTC_ALARM_ENA : 0);
+}
+
+static int ab8500_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alarm)
+{
+        struct ab8500 *ab8500 = dev_get_drvdata(dev->parent);
+        int retval, i;
+        unsigned char buf[ARRAY_SIZE(ab8500_rtc_alarm_regs)];
+        unsigned long mins, secs = 0;
+
+        if (alarm->time.tm_year < (AB8500_RTC_EPOCH - 1900)) {
+                dev_dbg(dev, "year should be equal to or greater than %d\n",
+                                AB8500_RTC_EPOCH);
+                return -EINVAL;
+        }
+
+        /* Get the number of seconds since 1970 */
+        rtc_tm_to_time(&alarm->time, &secs);
+
+        /*
+         * Convert it to the number of seconds since 01-01-2000 00:00:00, since
+         * we only have a small counter in the RTC.
+         */
+        secs -= get_elapsed_seconds(AB8500_RTC_EPOCH);
+
+        mins = secs / 60;
+
+        buf[2] = mins & 0xFF;
+        buf[1] = (mins >> 8) & 0xFF;
+        buf[0] = (mins >> 16) & 0xFF;
+
+        /* Set the alarm time */
+        for (i = 0; i < ARRAY_SIZE(ab8500_rtc_alarm_regs); i++) {
+                retval = ab8500_write(ab8500, ab8500_rtc_alarm_regs[i], buf[i]);
+                if (retval < 0)
+                        return retval;
+        }
+
+        return ab8500_rtc_irq_enable(dev, alarm->enabled);
+}
+
+static irqreturn_t rtc_alarm_handler(int irq, void *data)
+{
+        struct rtc_device *rtc = data;
+        unsigned long events = RTC_IRQF | RTC_AF;
+
+        dev_dbg(&rtc->dev, "%s\n", __func__);
+        rtc_update_irq(rtc, 1, events);
+
+        return IRQ_HANDLED;
+}
+
+static const struct rtc_class_ops ab8500_rtc_ops = {
+        .read_time              = ab8500_rtc_read_time,
+        .set_time               = ab8500_rtc_set_time,
+        .read_alarm             = ab8500_rtc_read_alarm,
+        .set_alarm              = ab8500_rtc_set_alarm,
+        .alarm_irq_enable       = ab8500_rtc_irq_enable,
+};
+
+static int __devinit ab8500_rtc_probe(struct platform_device *pdev)
+{
+        struct ab8500 *ab8500 = dev_get_drvdata(pdev->dev.parent);
+        int err;
+        struct rtc_device *rtc;
+        int rtc_ctrl;
+        int irq;
+
+        irq = platform_get_irq_byname(pdev, "ALARM");
+        if (irq < 0)
+                return irq;
+
+        /* For RTC supply test */
+        err = ab8500_set_bits(ab8500, AB8500_RTC_STAT_REG, RTC_STATUS_DATA,
+                        RTC_STATUS_DATA);
+        if (err < 0)
+                return err;
+
+        /* Wait for reset by the PorRtc */
+        msleep(1);
+
+        rtc_ctrl = ab8500_read(ab8500, AB8500_RTC_STAT_REG);
+        if (rtc_ctrl < 0)
+                return rtc_ctrl;
+
+        /* Check if the RTC Supply fails */
+        if (!(rtc_ctrl & RTC_STATUS_DATA)) {
+                dev_err(&pdev->dev, "RTC supply failure\n");
+                return -ENODEV;
+        }
+
+        rtc = rtc_device_register("ab8500-rtc", &pdev->dev, &ab8500_rtc_ops,
+                        THIS_MODULE);
+        if (IS_ERR(rtc)) {
+                dev_err(&pdev->dev, "Registration failed\n");
+                err = PTR_ERR(rtc);
+                return err;
+        }
+
+        err = request_threaded_irq(irq, NULL, rtc_alarm_handler, 0,
+                                   "ab8500-rtc", rtc);
+        if (err < 0) {
+                rtc_device_unregister(rtc);
+                return err;
+        }
+
+        platform_set_drvdata(pdev, rtc);
+
+        return 0;
+}
+
+static int __devexit ab8500_rtc_remove(struct platform_device *pdev)
+{
+        struct rtc_device *rtc = platform_get_drvdata(pdev);
+        int irq = platform_get_irq_byname(pdev, "ALARM");
+
+        free_irq(irq, rtc);
+        rtc_device_unregister(rtc);
+        platform_set_drvdata(pdev, NULL);
+
+        return 0;
+}
+
+static struct platform_driver ab8500_rtc_driver = {
+        .driver = {
+                .name = "ab8500-rtc",
+                .owner = THIS_MODULE,
+        },
+        .probe  = ab8500_rtc_probe,
+        .remove = __devexit_p(ab8500_rtc_remove),
+};
+
+static int __init ab8500_rtc_init(void)
+{
+        return platform_driver_register(&ab8500_rtc_driver);
+}
+
+static void __exit ab8500_rtc_exit(void)
+{
+        platform_driver_unregister(&ab8500_rtc_driver);
+}
+
+module_init(ab8500_rtc_init);
+module_exit(ab8500_rtc_exit);
+MODULE_AUTHOR("Virupax Sadashivpetimath <virupax.sadashivpetimath@stericsson.com>");
+MODULE_DESCRIPTION("AB8500 RTC Driver");
+MODULE_LICENSE("GPL v2");