rtc: Add Epson RX8010SJ RTC driver

This driver supports the following functions:
 - reading and setting time
 - alarms when connected to an IRQ
 - reading and clearing the voltage low flags

Datasheet:
http://www.epsondevice.com/docs/qd/en/DownloadServlet?id=ID000956
Signed-off-by: Akshay Bhat <akshay.bhat@timesys.com>
Signed-off-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>

3 files changed, 534 insertions, 0 deletions

diff --git a/drivers/rtc/Kconfig b/drivers/rtc/Kconfig
index 2a52424..376322f 100644
--- a/drivers/rtc/Kconfig
+++ b/drivers/rtc/Kconfig
@@ -558,6 +558,16 @@ config RTC_DRV_FM3130
 	  This driver can also be built as a module. If so the module
 	  will be called rtc-fm3130.
 
+config RTC_DRV_RX8010
+	tristate "Epson RX8010SJ"
+	depends on I2C
+	help
+	  If you say yes here you get support for the Epson RX8010SJ RTC
+	  chip.
+
+	  This driver can also be built as a module. If so, the module
+	  will be called rtc-rx8010.
+
 config RTC_DRV_RX8581
 	tristate "Epson RX-8581"
 	help
diff --git a/drivers/rtc/Makefile b/drivers/rtc/Makefile
index 231f764..62d61b2 100644
--- a/drivers/rtc/Makefile
+++ b/drivers/rtc/Makefile
@@ -128,6 +128,7 @@ obj-$(CONFIG_RTC_DRV_RS5C372)	+= rtc-rs5c372.o
 obj-$(CONFIG_RTC_DRV_RV3029C2)	+= rtc-rv3029c2.o
 obj-$(CONFIG_RTC_DRV_RV8803)	+= rtc-rv8803.o
 obj-$(CONFIG_RTC_DRV_RX4581)	+= rtc-rx4581.o
+obj-$(CONFIG_RTC_DRV_RX8010)	+= rtc-rx8010.o
 obj-$(CONFIG_RTC_DRV_RX8025)	+= rtc-rx8025.o
 obj-$(CONFIG_RTC_DRV_RX8581)	+= rtc-rx8581.o
 obj-$(CONFIG_RTC_DRV_S35390A)	+= rtc-s35390a.o
diff --git a/drivers/rtc/rtc-rx8010.c b/drivers/rtc/rtc-rx8010.c
new file mode 100644
index 0000000..772d221
--- /dev/null
+++ b/drivers/rtc/rtc-rx8010.c
@@ -0,0 +1,523 @@
+/*
+ * Driver for the Epson RTC module RX-8010 SJ
+ *
+ * Copyright(C) Timesys Corporation 2015
+ * Copyright(C) General Electric Company 2015
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ */
+
+#include <linux/bcd.h>
+#include <linux/bitops.h>
+#include <linux/i2c.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/rtc.h>
+
+#define RX8010_SEC     0x10
+#define RX8010_MIN     0x11
+#define RX8010_HOUR    0x12
+#define RX8010_WDAY    0x13
+#define RX8010_MDAY    0x14
+#define RX8010_MONTH   0x15
+#define RX8010_YEAR    0x16
+#define RX8010_YEAR    0x16
+#define RX8010_RESV17  0x17
+#define RX8010_ALMIN   0x18
+#define RX8010_ALHOUR  0x19
+#define RX8010_ALWDAY  0x1A
+#define RX8010_TCOUNT0 0x1B
+#define RX8010_TCOUNT1 0x1C
+#define RX8010_EXT     0x1D
+#define RX8010_FLAG    0x1E
+#define RX8010_CTRL    0x1F
+/* 0x20 to 0x2F are user registers */
+#define RX8010_RESV30  0x30
+#define RX8010_RESV31  0x32
+#define RX8010_IRQ     0x32
+
+#define RX8010_EXT_WADA  BIT(3)
+
+#define RX8010_FLAG_VLF  BIT(1)
+#define RX8010_FLAG_AF   BIT(3)
+#define RX8010_FLAG_TF   BIT(4)
+#define RX8010_FLAG_UF   BIT(5)
+
+#define RX8010_CTRL_AIE  BIT(3)
+#define RX8010_CTRL_UIE  BIT(5)
+#define RX8010_CTRL_STOP BIT(6)
+#define RX8010_CTRL_TEST BIT(7)
+
+#define RX8010_ALARM_AE  BIT(7)
+
+static const struct i2c_device_id rx8010_id[] = {
+	{ "rx8010", 0 },
+	{ }
+};
+MODULE_DEVICE_TABLE(i2c, rx8010_id);
+
+struct rx8010_data {
+	struct i2c_client *client;
+	struct rtc_device *rtc;
+	u8 ctrlreg;
+	spinlock_t flags_lock;
+};
+
+static irqreturn_t rx8010_irq_1_handler(int irq, void *dev_id)
+{
+	struct i2c_client *client = dev_id;
+	struct rx8010_data *rx8010 = i2c_get_clientdata(client);
+	int flagreg;
+
+	spin_lock(&rx8010->flags_lock);
+
+	flagreg = i2c_smbus_read_byte_data(client, RX8010_FLAG);
+
+	if (flagreg <= 0) {
+		spin_unlock(&rx8010->flags_lock);
+		return IRQ_NONE;
+	}
+
+	if (flagreg & RX8010_FLAG_VLF)
+		dev_warn(&client->dev, "Frequency stop detected\n");
+
+	if (flagreg & RX8010_FLAG_TF) {
+		flagreg &= ~RX8010_FLAG_TF;
+		rtc_update_irq(rx8010->rtc, 1, RTC_PF | RTC_IRQF);
+	}
+
+	if (flagreg & RX8010_FLAG_AF) {
+		flagreg &= ~RX8010_FLAG_AF;
+		rtc_update_irq(rx8010->rtc, 1, RTC_AF | RTC_IRQF);
+	}
+
+	if (flagreg & RX8010_FLAG_UF) {
+		flagreg &= ~RX8010_FLAG_UF;
+		rtc_update_irq(rx8010->rtc, 1, RTC_UF | RTC_IRQF);
+	}
+
+	i2c_smbus_write_byte_data(client, RX8010_FLAG, flagreg);
+
+	spin_unlock(&rx8010->flags_lock);
+	return IRQ_HANDLED;
+}
+
+static int rx8010_get_time(struct device *dev, struct rtc_time *dt)
+{
+	struct rx8010_data *rx8010 = dev_get_drvdata(dev);
+	u8 date[7];
+	int flagreg;
+	int err;
+
+	flagreg = i2c_smbus_read_byte_data(rx8010->client, RX8010_FLAG);
+	if (flagreg < 0)
+		return flagreg;
+
+	if (flagreg & RX8010_FLAG_VLF) {
+		dev_warn(dev, "Frequency stop detected\n");
+		return -EINVAL;
+	}
+
+	err = i2c_smbus_read_i2c_block_data(rx8010->client, RX8010_SEC,
+					    7, date);
+	if (err != 7)
+		return err < 0 ? err : -EIO;
+
+	dt->tm_sec = bcd2bin(date[RX8010_SEC - RX8010_SEC] & 0x7f);
+	dt->tm_min = bcd2bin(date[RX8010_MIN - RX8010_SEC] & 0x7f);
+	dt->tm_hour = bcd2bin(date[RX8010_HOUR - RX8010_SEC] & 0x3f);
+	dt->tm_mday = bcd2bin(date[RX8010_MDAY - RX8010_SEC] & 0x3f);
+	dt->tm_mon = bcd2bin(date[RX8010_MONTH - RX8010_SEC] & 0x1f) - 1;
+	dt->tm_year = bcd2bin(date[RX8010_YEAR - RX8010_SEC]) + 100;
+	dt->tm_wday = ffs(date[RX8010_WDAY - RX8010_SEC] & 0x7f);
+
+	return rtc_valid_tm(dt);
+}
+
+static int rx8010_set_time(struct device *dev, struct rtc_time *dt)
+{
+	struct rx8010_data *rx8010 = dev_get_drvdata(dev);
+	u8 date[7];
+	int ctrl, flagreg;
+	int ret;
+	unsigned long irqflags;
+
+	if ((dt->tm_year < 100) || (dt->tm_year > 199))
+		return -EINVAL;
+
+	/* set STOP bit before changing clock/calendar */
+	ctrl = i2c_smbus_read_byte_data(rx8010->client, RX8010_CTRL);
+	if (ctrl < 0)
+		return ctrl;
+	rx8010->ctrlreg = ctrl | RX8010_CTRL_STOP;
+	ret = i2c_smbus_write_byte_data(rx8010->client, RX8010_CTRL,
+					rx8010->ctrlreg);
+	if (ret < 0)
+		return ret;
+
+	date[RX8010_SEC - RX8010_SEC] = bin2bcd(dt->tm_sec);
+	date[RX8010_MIN - RX8010_SEC] = bin2bcd(dt->tm_min);
+	date[RX8010_HOUR - RX8010_SEC] = bin2bcd(dt->tm_hour);
+	date[RX8010_MDAY - RX8010_SEC] = bin2bcd(dt->tm_mday);
+	date[RX8010_MONTH - RX8010_SEC] = bin2bcd(dt->tm_mon + 1);
+	date[RX8010_YEAR - RX8010_SEC] = bin2bcd(dt->tm_year - 100);
+	date[RX8010_WDAY - RX8010_SEC] = bin2bcd(1 << dt->tm_wday);
+
+	ret = i2c_smbus_write_i2c_block_data(rx8010->client,
+					     RX8010_SEC, 7, date);
+	if (ret < 0)
+		return ret;
+
+	/* clear STOP bit after changing clock/calendar */
+	ctrl = i2c_smbus_read_byte_data(rx8010->client, RX8010_CTRL);
+	if (ctrl < 0)
+		return ctrl;
+	rx8010->ctrlreg = ctrl & ~RX8010_CTRL_STOP;
+	ret = i2c_smbus_write_byte_data(rx8010->client, RX8010_CTRL,
+					rx8010->ctrlreg);
+	if (ret < 0)
+		return ret;
+
+	spin_lock_irqsave(&rx8010->flags_lock, irqflags);
+
+	flagreg = i2c_smbus_read_byte_data(rx8010->client, RX8010_FLAG);
+	if (flagreg < 0) {
+		spin_unlock_irqrestore(&rx8010->flags_lock, irqflags);
+		return flagreg;
+	}
+
+	if (flagreg & RX8010_FLAG_VLF)
+		ret = i2c_smbus_write_byte_data(rx8010->client, RX8010_FLAG,
+						flagreg & ~RX8010_FLAG_VLF);
+
+	spin_unlock_irqrestore(&rx8010->flags_lock, irqflags);
+
+	return 0;
+}
+
+static int rx8010_init_client(struct i2c_client *client)
+{
+	struct rx8010_data *rx8010 = i2c_get_clientdata(client);
+	u8 ctrl[2];
+	int need_clear = 0, err = 0;
+
+	/* Initialize reserved registers as specified in datasheet */
+	err = i2c_smbus_write_byte_data(client, RX8010_RESV17, 0xD8);
+	if (err < 0)
+		return err;
+
+	err = i2c_smbus_write_byte_data(client, RX8010_RESV30, 0x00);
+	if (err < 0)
+		return err;
+
+	err = i2c_smbus_write_byte_data(client, RX8010_RESV31, 0x08);
+	if (err < 0)
+		return err;
+
+	err = i2c_smbus_write_byte_data(client, RX8010_IRQ, 0x00);
+	if (err < 0)
+		return err;
+
+	err = i2c_smbus_read_i2c_block_data(rx8010->client, RX8010_FLAG,
+					    2, ctrl);
+	if (err != 2)
+		return err < 0 ? err : -EIO;
+
+	if (ctrl[0] & RX8010_FLAG_VLF)
+		dev_warn(&client->dev, "Frequency stop was detected\n");
+
+	if (ctrl[0] & RX8010_FLAG_AF) {
+		dev_warn(&client->dev, "Alarm was detected\n");
+		need_clear = 1;
+	}
+
+	if (ctrl[0] & RX8010_FLAG_TF)
+		need_clear = 1;
+
+	if (ctrl[0] & RX8010_FLAG_UF)
+		need_clear = 1;
+
+	if (need_clear) {
+		ctrl[0] &= ~(RX8010_FLAG_AF | RX8010_FLAG_TF | RX8010_FLAG_UF);
+		err = i2c_smbus_write_byte_data(client, RX8010_FLAG, ctrl[0]);
+		if (err < 0)
+			return err;
+	}
+
+	rx8010->ctrlreg = (ctrl[1] & ~RX8010_CTRL_TEST);
+
+	return err;
+}
+
+static int rx8010_read_alarm(struct device *dev, struct rtc_wkalrm *t)
+{
+	struct rx8010_data *rx8010 = dev_get_drvdata(dev);
+	struct i2c_client *client = rx8010->client;
+	u8 alarmvals[3];
+	int flagreg;
+	int err;
+
+	err = i2c_smbus_read_i2c_block_data(client, RX8010_ALMIN, 3, alarmvals);
+	if (err != 3)
+		return err < 0 ? err : -EIO;
+
+	flagreg = i2c_smbus_read_byte_data(client, RX8010_FLAG);
+	if (flagreg < 0)
+		return flagreg;
+
+	t->time.tm_sec = 0;
+	t->time.tm_min = bcd2bin(alarmvals[0] & 0x7f);
+	t->time.tm_hour = bcd2bin(alarmvals[1] & 0x3f);
+
+	if (alarmvals[2] & RX8010_ALARM_AE)
+		t->time.tm_mday = -1;
+	else
+		t->time.tm_mday = bcd2bin(alarmvals[2] & 0x7f);
+
+	t->time.tm_wday = -1;
+	t->time.tm_mon = -1;
+	t->time.tm_year = -1;
+
+	t->enabled = !!(rx8010->ctrlreg & RX8010_CTRL_AIE);
+	t->pending = (flagreg & RX8010_FLAG_AF) && t->enabled;
+
+	return err;
+}
+
+static int rx8010_set_alarm(struct device *dev, struct rtc_wkalrm *t)
+{
+	struct i2c_client *client = to_i2c_client(dev);
+	struct rx8010_data *rx8010 = dev_get_drvdata(dev);
+	u8 alarmvals[3];
+	int extreg, flagreg;
+	int err;
+	unsigned long irqflags;
+
+	spin_lock_irqsave(&rx8010->flags_lock, irqflags);
+	flagreg = i2c_smbus_read_byte_data(client, RX8010_FLAG);
+	if (flagreg < 0) {
+		spin_unlock_irqrestore(&rx8010->flags_lock, irqflags);
+		return flagreg;
+	}
+
+	if (rx8010->ctrlreg & (RX8010_CTRL_AIE | RX8010_CTRL_UIE)) {
+		rx8010->ctrlreg &= ~(RX8010_CTRL_AIE | RX8010_CTRL_UIE);
+		err = i2c_smbus_write_byte_data(rx8010->client, RX8010_CTRL,
+						rx8010->ctrlreg);
+		if (err < 0) {
+			spin_unlock_irqrestore(&rx8010->flags_lock, irqflags);
+			return err;
+		}
+	}
+
+	flagreg &= ~RX8010_FLAG_AF;
+	err = i2c_smbus_write_byte_data(rx8010->client, RX8010_FLAG, flagreg);
+	spin_unlock_irqrestore(&rx8010->flags_lock, irqflags);
+	if (err < 0)
+		return err;
+
+	alarmvals[0] = bin2bcd(t->time.tm_min);
+	alarmvals[1] = bin2bcd(t->time.tm_hour);
+	alarmvals[2] = bin2bcd(t->time.tm_mday);
+
+	err = i2c_smbus_write_i2c_block_data(rx8010->client, RX8010_ALMIN,
+					     2, alarmvals);
+	if (err < 0)
+		return err;
+
+	extreg = i2c_smbus_read_byte_data(client, RX8010_EXT);
+	if (extreg < 0)
+		return extreg;
+
+	extreg |= RX8010_EXT_WADA;
+	err = i2c_smbus_write_byte_data(rx8010->client, RX8010_EXT, extreg);
+	if (err < 0)
+		return err;
+
+	if (alarmvals[2] == 0)
+		alarmvals[2] |= RX8010_ALARM_AE;
+
+	err = i2c_smbus_write_byte_data(rx8010->client, RX8010_ALWDAY,
+					alarmvals[2]);
+	if (err < 0)
+		return err;
+
+	if (t->enabled) {
+		if (rx8010->rtc->uie_rtctimer.enabled)
+			rx8010->ctrlreg |= RX8010_CTRL_UIE;
+		if (rx8010->rtc->aie_timer.enabled)
+			rx8010->ctrlreg |=
+				(RX8010_CTRL_AIE | RX8010_CTRL_UIE);
+
+		err = i2c_smbus_write_byte_data(rx8010->client, RX8010_CTRL,
+						rx8010->ctrlreg);
+		if (err < 0)
+			return err;
+	}
+
+	return 0;
+}
+
+static int rx8010_alarm_irq_enable(struct device *dev,
+				   unsigned int enabled)
+{
+	struct i2c_client *client = to_i2c_client(dev);
+	struct rx8010_data *rx8010 = dev_get_drvdata(dev);
+	int flagreg;
+	u8 ctrl;
+	int err;
+
+	ctrl = rx8010->ctrlreg;
+
+	if (enabled) {
+		if (rx8010->rtc->uie_rtctimer.enabled)
+			ctrl |= RX8010_CTRL_UIE;
+		if (rx8010->rtc->aie_timer.enabled)
+			ctrl |= (RX8010_CTRL_AIE | RX8010_CTRL_UIE);
+	} else {
+		if (!rx8010->rtc->uie_rtctimer.enabled)
+			ctrl &= ~RX8010_CTRL_UIE;
+		if (!rx8010->rtc->aie_timer.enabled)
+			ctrl &= ~RX8010_CTRL_AIE;
+	}
+
+	flagreg = i2c_smbus_read_byte_data(client, RX8010_FLAG);
+	if (flagreg < 0)
+		return flagreg;
+
+	flagreg &= ~RX8010_FLAG_AF;
+	err = i2c_smbus_write_byte_data(rx8010->client, RX8010_FLAG, flagreg);
+	if (err < 0)
+		return err;
+
+	if (ctrl != rx8010->ctrlreg) {
+		rx8010->ctrlreg = ctrl;
+		err = i2c_smbus_write_byte_data(rx8010->client, RX8010_CTRL,
+						rx8010->ctrlreg);
+		if (err < 0)
+			return err;
+	}
+
+	return 0;
+}
+
+static int rx8010_ioctl(struct device *dev, unsigned int cmd, unsigned long arg)
+{
+	struct i2c_client *client = to_i2c_client(dev);
+	struct rx8010_data *rx8010 = dev_get_drvdata(dev);
+	int ret, tmp;
+	int flagreg;
+	unsigned long irqflags;
+
+	switch (cmd) {
+	case RTC_VL_READ:
+		flagreg = i2c_smbus_read_byte_data(rx8010->client, RX8010_FLAG);
+		if (flagreg < 0)
+			return flagreg;
+
+		tmp = !!(flagreg & RX8010_FLAG_VLF);
+		if (copy_to_user((void __user *)arg, &tmp, sizeof(int)))
+			return -EFAULT;
+
+		return 0;
+
+	case RTC_VL_CLR:
+		spin_lock_irqsave(&rx8010->flags_lock, irqflags);
+		flagreg = i2c_smbus_read_byte_data(rx8010->client, RX8010_FLAG);
+		if (flagreg < 0) {
+			spin_unlock_irqrestore(&rx8010->flags_lock, irqflags);
+			return flagreg;
+		}
+
+		flagreg &= ~RX8010_FLAG_VLF;
+		ret = i2c_smbus_write_byte_data(client, RX8010_FLAG, flagreg);
+		spin_unlock_irqrestore(&rx8010->flags_lock, irqflags);
+		if (ret < 0)
+			return ret;
+
+		return 0;
+
+	default:
+		return -ENOIOCTLCMD;
+	}
+}
+
+static struct rtc_class_ops rx8010_rtc_ops = {
+	.read_time = rx8010_get_time,
+	.set_time = rx8010_set_time,
+	.ioctl = rx8010_ioctl,
+};
+
+static int rx8010_probe(struct i2c_client *client,
+			const struct i2c_device_id *id)
+{
+	struct i2c_adapter *adapter = to_i2c_adapter(client->dev.parent);
+	struct rx8010_data *rx8010;
+	int err = 0;
+
+	if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA
+		| I2C_FUNC_SMBUS_I2C_BLOCK)) {
+		dev_err(&adapter->dev, "doesn't support required functionality\n");
+		return -EIO;
+	}
+
+	rx8010 = devm_kzalloc(&client->dev, sizeof(struct rx8010_data),
+			      GFP_KERNEL);
+	if (!rx8010)
+		return -ENOMEM;
+
+	rx8010->client = client;
+	i2c_set_clientdata(client, rx8010);
+
+	spin_lock_init(&rx8010->flags_lock);
+
+	err = rx8010_init_client(client);
+	if (err)
+		return err;
+
+	if (client->irq > 0) {
+		dev_info(&client->dev, "IRQ %d supplied\n", client->irq);
+		err = devm_request_threaded_irq(&client->dev, client->irq, NULL,
+						rx8010_irq_1_handler,
+						IRQF_TRIGGER_LOW | IRQF_ONESHOT,
+						"rx8010", client);
+
+		if (err) {
+			dev_err(&client->dev, "unable to request IRQ\n");
+			client->irq = 0;
+		} else {
+			rx8010_rtc_ops.read_alarm = rx8010_read_alarm;
+			rx8010_rtc_ops.set_alarm = rx8010_set_alarm;
+			rx8010_rtc_ops.alarm_irq_enable = rx8010_alarm_irq_enable;
+		}
+	}
+
+	rx8010->rtc = devm_rtc_device_register(&client->dev, client->name,
+		&rx8010_rtc_ops, THIS_MODULE);
+
+	if (IS_ERR(rx8010->rtc)) {
+		dev_err(&client->dev, "unable to register the class device\n");
+		return PTR_ERR(rx8010->rtc);
+	}
+
+	rx8010->rtc->max_user_freq = 1;
+
+	return err;
+}
+
+static struct i2c_driver rx8010_driver = {
+	.driver = {
+		.name = "rtc-rx8010",
+	},
+	.probe		= rx8010_probe,
+	.id_table	= rx8010_id,
+};
+
+module_i2c_driver(rx8010_driver);
+
+MODULE_AUTHOR("Akshay Bhat <akshay.bhat@timesys.com>");
+MODULE_DESCRIPTION("Epson RX8010SJ RTC driver");
+MODULE_LICENSE("GPL v2");