rtc: add RTC driver for TPS6586x

Add an RTC driver for TPS6586X chips by TI.  This driver supports:

- Setting and getting time and date.
- Setting and reading alarm time.
- Alarm and interrupt functionlity.

[akpm@linux-foundation.org: remove stray semicolons]
[akpm@linux-foundation.org: start epoch in 2009]
Signed-off-by: Laxman Dewangan <ldewangan@nvidia.com>
Tested-by: Marc Dietrich <marvin24@gmx.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

3 files changed, 365 insertions, 0 deletions

diff --git a/drivers/rtc/Kconfig b/drivers/rtc/Kconfig
index d0cea02b5dfc..923a9da9c829 100644
--- a/drivers/rtc/Kconfig
+++ b/drivers/rtc/Kconfig
@@ -352,6 +352,14 @@ config RTC_DRV_TWL4030
           This driver can also be built as a module. If so, the module
           will be called rtc-twl.
 
+config RTC_DRV_TPS6586X
+        tristate "TI TPS6586X RTC driver"
+        depends on MFD_TPS6586X
+        help
+          TI Power Managment IC TPS6586X supports RTC functionality
+          along with alarm. This driver supports the RTC driver for
+          the TPS6586X RTC module.
+
 config RTC_DRV_TPS65910
         tristate "TI TPS65910 RTC driver"
         depends on RTC_CLASS && MFD_TPS65910
diff --git a/drivers/rtc/Makefile b/drivers/rtc/Makefile
index c3f62c80dc06..4418ef3f9ecc 100644
--- a/drivers/rtc/Makefile
+++ b/drivers/rtc/Makefile
@@ -111,6 +111,7 @@ obj-$(CONFIG_RTC_DRV_TEGRA)	+= rtc-tegra.o
 obj-$(CONFIG_RTC_DRV_TEST)      += rtc-test.o
 obj-$(CONFIG_RTC_DRV_TILE)      += rtc-tile.o
 obj-$(CONFIG_RTC_DRV_TWL4030)   += rtc-twl.o
+obj-$(CONFIG_RTC_DRV_TPS6586X)  += rtc-tps6586x.o
 obj-$(CONFIG_RTC_DRV_TPS65910)  += rtc-tps65910.o
 obj-$(CONFIG_RTC_DRV_TX4939)    += rtc-tx4939.o
 obj-$(CONFIG_RTC_DRV_V3020)     += rtc-v3020.o
diff --git a/drivers/rtc/rtc-tps6586x.c b/drivers/rtc/rtc-tps6586x.c
new file mode 100644
index 000000000000..70f61b8e9e6f
--- /dev/null
+++ b/drivers/rtc/rtc-tps6586x.c
@@ -0,0 +1,356 @@
+/*
+ * rtc-tps6586x.c: RTC driver for TI PMIC TPS6586X
+ *
+ * Copyright (c) 2012, NVIDIA Corporation.
+ *
+ * Author: Laxman Dewangan <ldewangan@nvidia.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 version 2.
+ *
+ * This program is distributed "as is" WITHOUT ANY WARRANTY of any kind,
+ * whether express or implied; 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., 59 Temple Place, Suite 330, Boston, MA
+ * 02111-1307, USA
+ */
+
+#include <linux/device.h>
+#include <linux/err.h>
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/mfd/tps6586x.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/pm_runtime.h>
+#include <linux/rtc.h>
+#include <linux/slab.h>
+
+#define RTC_CTRL                        0xc0
+#define POR_RESET_N                     BIT(7)
+#define OSC_SRC_SEL                     BIT(6)
+#define RTC_ENABLE                      BIT(5)  /* enables alarm */
+#define RTC_BUF_ENABLE                  BIT(4)  /* 32 KHz buffer enable */
+#define PRE_BYPASS                      BIT(3)  /* 0=1KHz or 1=32KHz updates */
+#define CL_SEL_MASK                     (BIT(2)|BIT(1))
+#define CL_SEL_POS                      1
+#define RTC_ALARM1_HI                   0xc1
+#define RTC_COUNT4                      0xc6
+
+/* start a PMU RTC access by reading the register prior to the RTC_COUNT4 */
+#define RTC_COUNT4_DUMMYREAD            0xc5
+
+/*only 14-bits width in second*/
+#define ALM1_VALID_RANGE_IN_SEC         0x3FFF
+
+#define TPS6586X_RTC_CL_SEL_1_5PF       0x0
+#define TPS6586X_RTC_CL_SEL_6_5PF       0x1
+#define TPS6586X_RTC_CL_SEL_7_5PF       0x2
+#define TPS6586X_RTC_CL_SEL_12_5PF      0x3
+
+struct tps6586x_rtc {
+        struct device           *dev;
+        struct rtc_device       *rtc;
+        int                     irq;
+        bool                    irq_en;
+        unsigned long long      epoch_start;
+};
+
+static inline struct device *to_tps6586x_dev(struct device *dev)
+{
+        return dev->parent;
+}
+
+static int tps6586x_rtc_read_time(struct device *dev, struct rtc_time *tm)
+{
+        struct tps6586x_rtc *rtc = dev_get_drvdata(dev);
+        struct device *tps_dev = to_tps6586x_dev(dev);
+        unsigned long long ticks = 0;
+        unsigned long seconds;
+        u8 buff[6];
+        int ret;
+        int i;
+
+        ret = tps6586x_reads(tps_dev, RTC_COUNT4_DUMMYREAD, sizeof(buff), buff);
+        if (ret < 0) {
+                dev_err(dev, "read counter failed with err %d\n", ret);
+                return ret;
+        }
+
+        for (i = 1; i < sizeof(buff); i++) {
+                ticks <<= 8;
+                ticks |= buff[i];
+        }
+
+        seconds = ticks >> 10;
+        seconds += rtc->epoch_start;
+        rtc_time_to_tm(seconds, tm);
+        return rtc_valid_tm(tm);
+}
+
+static int tps6586x_rtc_set_time(struct device *dev, struct rtc_time *tm)
+{
+        struct tps6586x_rtc *rtc = dev_get_drvdata(dev);
+        struct device *tps_dev = to_tps6586x_dev(dev);
+        unsigned long long ticks;
+        unsigned long seconds;
+        u8 buff[5];
+        int ret;
+
+        rtc_tm_to_time(tm, &seconds);
+        if (seconds < rtc->epoch_start) {
+                dev_err(dev, "requested time unsupported\n");
+                return -EINVAL;
+        }
+        seconds -= rtc->epoch_start;
+
+        ticks = (unsigned long long)seconds << 10;
+        buff[0] = (ticks >> 32) & 0xff;
+        buff[1] = (ticks >> 24) & 0xff;
+        buff[2] = (ticks >> 16) & 0xff;
+        buff[3] = (ticks >> 8) & 0xff;
+        buff[4] = ticks & 0xff;
+
+        /* Disable RTC before changing time */
+        ret = tps6586x_clr_bits(tps_dev, RTC_CTRL, RTC_ENABLE);
+        if (ret < 0) {
+                dev_err(dev, "failed to clear RTC_ENABLE\n");
+                return ret;
+        }
+
+        ret = tps6586x_writes(tps_dev, RTC_COUNT4, sizeof(buff), buff);
+        if (ret < 0) {
+                dev_err(dev, "failed to program new time\n");
+                return ret;
+        }
+
+        /* Enable RTC */
+        ret = tps6586x_set_bits(tps_dev, RTC_CTRL, RTC_ENABLE);
+        if (ret < 0) {
+                dev_err(dev, "failed to set RTC_ENABLE\n");
+                return ret;
+        }
+        return 0;
+}
+
+static int tps6586x_rtc_alarm_irq_enable(struct device *dev,
+                         unsigned int enabled)
+{
+        struct tps6586x_rtc *rtc = dev_get_drvdata(dev);
+
+        if (enabled && !rtc->irq_en) {
+                enable_irq(rtc->irq);
+                rtc->irq_en = true;
+        } else if (!enabled && rtc->irq_en)  {
+                disable_irq(rtc->irq);
+                rtc->irq_en = false;
+        }
+        return 0;
+}
+
+static int tps6586x_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alrm)
+{
+        struct tps6586x_rtc *rtc = dev_get_drvdata(dev);
+        struct device *tps_dev = to_tps6586x_dev(dev);