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 2a524244afec..376322f71fd5 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 231f76451615..62d61b26ca7e 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 000000000000..772d221ec2d9
--- /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");