mfd: tps6586x: add RTC driver for TI TPS6586x

Change-Id: Ie22a19b662fda6365b1c514aaf83c9de12fabbd4
Signed-off-by: Gary King <gking@nvidia.com>

drivers/rtc/Kconfig

@@ -286,6 +286,13 @@ config RTC_DRV_DM355EVM
 	help
 	  Supports the RTC firmware in the MSP430 on the DM355 EVM.
 
+config RTC_DRV_TPS6586X
+	tristate "TI TPS6586X RTC"
+	depends on I2C
+	select MFD_TPS6586X
+	help
+	  This driver supports TPS6586X RTC
+
 config RTC_DRV_TWL92330
 	boolean "TI TWL92330/Menelaus"
 	depends on MENELAUS

drivers/rtc/Makefile

@@ -91,6 +91,7 @@ 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_TEST)	+= rtc-test.o
+obj-$(CONFIG_RTC_DRV_TPS6586X)	+= rtc-tps6586x.o
 obj-$(CONFIG_RTC_DRV_TWL4030)	+= rtc-twl.o
 obj-$(CONFIG_RTC_DRV_TX4939)	+= rtc-tx4939.o
 obj-$(CONFIG_RTC_DRV_V3020)	+= rtc-v3020.o

drivers/rtc/rtc-tps6586x.c

@@ -0,0 +1,203 @@
+/*
+ * drivers/rtc/rtc-tps6586x.c
+ *
+ * RTC driver for TI TPS6586x
+ *
+ * Copyright (c) 2010, NVIDIA Corporation.
+ *
+ * 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/device.h>
+#include <linux/err.h>
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/mfd/tps6586x.h>
+#include <linux/platform_device.h>
+#include <linux/rtc.h>
+#include <linux/slab.h>
+
+#define TPS_EPOCH	2009
+
+#define RTC_CTRL	0xc0
+#  define RTC_ENABLE	(1 << 5)	/* enables tick updates */
+#  define RTC_HIRES	(1 << 4)	/* 1Khz or 32Khz updates */
+#define RTC_ALARM1_HI	0xc1
+#define RTC_COUNT4	0xc6
+
+struct tps6586x_rtc {
+	unsigned long     epoch_start;
+	struct rtc_device *rtc;
+};
+
+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[5];
+	int err;
+	int i;
+
+	err = tps6586x_reads(tps_dev, RTC_COUNT4, sizeof(buff), buff);
+	if (err < 0) {
+		dev_err(dev, "failed to read counter\n");
+		return err;
+	}
+
+	for (i = 0; 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 err;
+
+	rtc_tm_to_time(tm, &seconds);
+
+	if (WARN_ON(seconds < rtc->epoch_start)) {
+		dev_err(dev, "requested time unsupported\n");
+		return -EINVAL;
+	}
+
+	seconds -= rtc->epoch_start;
+
+	ticks = 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;
+
+	dev_info(dev, "setting time to %lu seconds (%llu ticks)\n",
+		 seconds, ticks);
+	
+
+	err = tps6586x_clr_bits(tps_dev, RTC_CTRL, RTC_ENABLE);
+	if (err < 0) {
+		dev_err(dev, "failed to clear RTC_ENABLE\n");
+		return err;
+	}
+
+	err = tps6586x_writes(tps_dev, RTC_COUNT4, sizeof(buff), buff);
+	if (err < 0) {
+		dev_err(dev, "failed to program new time\n");
+		return err;
+	}
+
+	err = tps6586x_set_bits(tps_dev, RTC_CTRL, RTC_ENABLE);
+	if (err < 0) {
+		dev_err(dev, "failed to set RTC_ENABLE\n");
+		return err;
+	}
+
+	return 0;
+}
+
+static const struct rtc_class_ops tps6586x_rtc_ops = {
+	.read_time	= tps6586x_rtc_read_time,
+	.set_time	= tps6586x_rtc_set_time,
+};
+
+static int __devinit tps6586x_rtc_probe(struct platform_device *pdev)
+{
+	struct device *tps_dev = to_tps6586x_dev(&pdev->dev);
+	struct tps6586x_rtc *rtc;
+	int err;
+
+	rtc = kzalloc(sizeof(*rtc), GFP_KERNEL);
+
+	if (!rtc)
+		return -ENOMEM;
+
+	rtc->epoch_start = mktime(TPS_EPOCH, 1, 1, 0, 0, 0);
+	rtc->rtc = rtc_device_register("tps6586x-rtc", &pdev->dev,
+				       &tps6586x_rtc_ops, THIS_MODULE);
+
+	if (IS_ERR(rtc->rtc)) {
+		err = PTR_ERR(rtc->rtc);
+		goto fail;
+	}
+
+	/* disable high-res mode, enable tick counting */
+	err = tps6586x_update(tps_dev, RTC_CTRL,
+			      (RTC_ENABLE | RTC_HIRES), RTC_ENABLE);
+	if (err < 0) {
+		dev_err(&pdev->dev, "unable to start counter\n");
+		goto fail;
+	}
+
+	dev_set_drvdata(&pdev->dev, rtc);
+	return 0;
+
+fail:
+	if (!IS_ERR_OR_NULL(rtc->rtc))
+		rtc_device_unregister(rtc->rtc);
+	kfree(rtc);
+	return err;
+}
+
+static int __devexit tps6586x_rtc_remove(struct platform_device *pdev)
+{
+	struct tps6586x_rtc *rtc = dev_get_drvdata(&pdev->dev);
+
+	rtc_device_unregister(rtc->rtc);
+	kfree(rtc);
+	return 0;
+}
+
+static struct platform_driver tps6586x_rtc_driver = {
+	.driver	= {
+		.name	= "tps6586x-rtc",
+		.owner	= THIS_MODULE,
+	},
+	.probe	= tps6586x_rtc_probe,
+	.remove	= __devexit_p(tps6586x_rtc_remove),
+};
+
+static int __init tps6586x_rtc_init(void)
+{
+	return platform_driver_register(&tps6586x_rtc_driver);
+}
+module_init(tps6586x_rtc_init);
+
+static void __exit tps6586x_rtc_exit(void)
+{
+	platform_driver_unregister(&tps6586x_rtc_driver);
+}
+module_exit(tps6586x_rtc_exit);
+
+MODULE_DESCRIPTION("TI TPS6586x RTC driver");
+MODULE_AUTHOR("NVIDIA Corporation");
+MODULE_LICENSE("GPL");