rtc: Add a driver for Micro Crystal RV8803

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

Signed-off-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>

3 files changed, 531 insertions, 0 deletions

diff --git a/drivers/rtc/Kconfig b/drivers/rtc/Kconfig
index 57c2dbc4f438..2a524244afec 100644
--- a/drivers/rtc/Kconfig
+++ b/drivers/rtc/Kconfig
@@ -593,6 +593,15 @@ config RTC_DRV_RV3029C2
           This driver can also be built as a module. If so, the module
           will be called rtc-rv3029c2.
 
+config RTC_DRV_RV8803
+        tristate "Micro Crystal RV8803"
+        help
+          If you say yes here you get support for the Micro Crystal
+          RV8803 RTC chips.
+
+          This driver can also be built as a module. If so, the module
+          will be called rtc-rv8803.
+
 config RTC_DRV_S5M
         tristate "Samsung S2M/S5M series"
         depends on MFD_SEC_CORE
diff --git a/drivers/rtc/Makefile b/drivers/rtc/Makefile
index e491eb524434..231f76451615 100644
--- a/drivers/rtc/Makefile
+++ b/drivers/rtc/Makefile
@@ -126,6 +126,7 @@ obj-$(CONFIG_RTC_DRV_RS5C313)	+= rtc-rs5c313.o
 obj-$(CONFIG_RTC_DRV_RS5C348)   += rtc-rs5c348.o
 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-$(CONFIG_RTC_DRV_RX8025)    += rtc-rx8025.o
 obj-$(CONFIG_RTC_DRV_RX8581)    += rtc-rx8581.o
diff --git a/drivers/rtc/rtc-rv8803.c b/drivers/rtc/rtc-rv8803.c
new file mode 100644
index 000000000000..e7329e21bfe3
--- /dev/null
+++ b/drivers/rtc/rtc-rv8803.c
@@ -0,0 +1,521 @@
+/*
+ * RTC driver for the Micro Crystal RV8803
+ *
+ * Copyright (C) 2015 Micro Crystal SA
+ *
+ * Alexandre Belloni <alexandre.belloni@free-electrons.com>
+ *
+ * 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/interrupt.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/rtc.h>
+
+#define RV8803_SEC                      0x00
+#define RV8803_MIN                      0x01
+#define RV8803_HOUR                     0x02
+#define RV8803_WEEK                     0x03
+#define RV8803_DAY                      0x04
+#define RV8803_MONTH                    0x05
+#define RV8803_YEAR                     0x06
+#define RV8803_RAM                      0x07
+#define RV8803_ALARM_MIN                0x08
+#define RV8803_ALARM_HOUR               0x09
+#define RV8803_ALARM_WEEK_OR_DAY        0x0A
+#define RV8803_EXT                      0x0D
+#define RV8803_FLAG                     0x0E
+#define RV8803_CTRL                     0x0F
+
+#define RV8803_EXT_WADA                 BIT(6)
+
+#define RV8803_FLAG_V1F                 BIT(0)
+#define RV8803_FLAG_V2F                 BIT(1)
+#define RV8803_FLAG_AF                  BIT(3)
+#define RV8803_FLAG_TF                  BIT(4)
+#define RV8803_FLAG_UF                  BIT(5)
+
+#define RV8803_CTRL_RESET               BIT(0)
+
+#define RV8803_CTRL_EIE                 BIT(2)
+#define RV8803_CTRL_AIE                 BIT(3)
+#define RV8803_CTRL_TIE                 BIT(4)
+#define RV8803_CTRL_UIE                 BIT(5)
+
+struct rv8803_data {
+        struct i2c_client *client;
+        struct rtc_device *rtc;
+        spinlock_t flags_lock;
+        u8 ctrl;
+};
+
+static irqreturn_t rv8803_handle_irq(int irq, void *dev_id)
+{
+        struct i2c_client *client = dev_id;
+        struct rv8803_data *rv8803 = i2c_get_clientdata(client);
+        unsigned long events = 0;
+        u8 flags;
+
+        spin_lock(&rv8803->flags_lock);
+
+        flags = i2c_smbus_read_byte_data(client, RV8803_FLAG);
+        if (flags <= 0) {
+                spin_unlock(&rv8803->flags_lock);
+                return IRQ_NONE;
+        }
+
+        if (flags & RV8803_FLAG_V1F)
+                dev_warn(&client->dev, "Voltage low, temperature compensation stopped.\n");
+
+        if (flags & RV8803_FLAG_V2F)
+                dev_warn(&client->dev, "Voltage low, data loss detected.\n");
+
+        if (flags & RV8803_FLAG_TF) {
+                flags &= ~RV8803_FLAG_TF;
+                rv8803->ctrl &= ~RV8803_CTRL_TIE;
+                events |= RTC_PF;
+        }
+
+        if (flags & RV8803_FLAG_AF) {
+                flags &= ~RV8803_FLAG_AF;
+                rv8803->ctrl &= ~RV8803_CTRL_AIE;
+                events |= RTC_AF;
+        }
+
+        if (flags & RV8803_FLAG_UF) {
+                flags &= ~RV8803_FLAG_UF;
+                rv8803->ctrl &= ~RV8803_CTRL_UIE;
+                events |= RTC_UF;
+        }
+
+        if (events) {
+                rtc_update_irq(rv8803->rtc, 1, events);
+                i2c_smbus_write_byte_data(client, RV8803_FLAG, flags);
+                i2c_smbus_write_byte_data(rv8803->client, RV8803_CTRL,
+                                          rv8803->ctrl);
+        }
+
+        spin_unlock(&rv8803->flags_lock);
+
+        return IRQ_HANDLED;
+}
+
+static int rv8803_get_time(struct device *dev, struct rtc_time *tm)
+{
+        struct rv8803_data *rv8803 = dev_get_drvdata(dev);
+        u8 date1[7];
+        u8 date2[7];
+        u8 *date = date1;
+        int ret, flags;
+
+        flags = i2c_smbus_read_byte_data(rv8803->client, RV8803_FLAG);
+        if (flags < 0)
+                return flags;
+
+        if (flags & RV8803_FLAG_V2F) {
+                dev_warn(dev, "Voltage low, data is invalid.\n");
+                return -EINVAL;
+        }
+
+        ret = i2c_smbus_read_i2c_block_data(rv8803->client, RV8803_SEC,
+                                            7, date);
+        if (ret != 7)
+                return ret < 0 ? ret : -EIO;
+
+        if ((date1[RV8803_SEC] & 0x7f) == bin2bcd(59)) {
+                ret = i2c_smbus_read_i2c_block_data(rv8803->client, RV8803_SEC,
+                                                    7, date2);
+                if (ret != 7)
+                        return ret < 0 ? ret : -EIO;
+
+                if ((date2[RV8803_SEC] & 0x7f) != bin2bcd(59))
+                        date = date2;
+        }
+
+        tm->tm_sec  = bcd2bin(date[RV8803_SEC] & 0x7f);
+        tm->tm_min  = bcd2bin(date[RV8803_MIN] & 0x7f);
+        tm->tm_hour = bcd2bin(date[RV8803_HOUR] & 0x3f);
+        tm->tm_wday = ffs(date[RV8803_WEEK] & 0x7f);
+        tm->tm_mday = bcd2bin(date[RV8803_DAY] & 0x3f);
+        tm->tm_mon  = bcd2bin(date[RV8803_MONTH] & 0x1f) - 1;
+        tm->tm_year = bcd2bin(date[RV8803_YEAR]) + 100;
+
+        return rtc_valid_tm(tm);
+}
+
+static int rv8803_set_time(struct device *dev, struct rtc_time *tm)
+{
+        struct rv8803_data *rv8803 = dev_get_drvdata(dev);
+        u8 date[7];
+        int flags, ret;
+        unsigned long irqflags;
+
+        if ((tm->tm_year < 100) || (tm->tm_year > 199))
+                return -EINVAL;
+
+        date[RV8803_SEC]   = bin2bcd(tm->tm_sec);
+        date[RV8803_MIN]   = bin2bcd(tm->tm_min);
+        date[RV8803_HOUR]  = bin2bcd(tm->tm_hour);
+        date[RV8803_WEEK]  = 1 << (tm->tm_wday);
+        date[RV8803_DAY]   = bin2bcd(tm->tm_mday);
+        date[RV8803_MONTH] = bin2bcd(tm->tm_mon + 1);
+        date[RV8803_YEAR]  = bin2bcd(tm->tm_year - 100);
+
+        ret = i2c_smbus_write_i2c_block_data(rv8803->client, RV8803_SEC,
+                                             7, date);
+        if (ret < 0)
+                return ret;
+
+        spin_lock_irqsave(&rv8803->flags_lock, irqflags);
+
+        flags = i2c_smbus_read_byte_data(rv8803->client, RV8803_FLAG);
+        if (flags < 0) {
+                spin_unlock_irqrestore(&rv8803->flags_lock, irqflags);
+                return flags;
+        }
+
+        ret = i2c_smbus_write_byte_data(rv8803->client, RV8803_FLAG,
+                                        flags & ~RV8803_FLAG_V2F);
+
+        spin_unlock_irqrestore(&rv8803->flags_lock, irqflags);
+
+        return ret;
+}
+
+static int rv8803_get_alarm(struct device *dev, struct rtc_wkalrm *alrm)
+{
+        struct rv8803_data *rv8803 = dev_get_drvdata(dev);
+        struct i2c_client *client = rv8803->client;
+        u8 alarmvals[3];
+        int flags, ret;
+
+        ret = i2c_smbus_read_i2c_block_data(client, RV8803_ALARM_MIN,
+                                            3, alarmvals);
+        if (ret != 3)
+                return ret < 0 ? ret : -EIO;
+
+        flags = i2c_smbus_read_byte_data(client, RV8803_FLAG);
+        if (flags < 0)
+                return flags;
+
+        alrm->time.tm_sec  = 0;
+        alrm->time.tm_min  = bcd2bin(alarmvals[0] & 0x7f);
+        alrm->time.tm_hour = bcd2bin(alarmvals[1] & 0x3f);
+        alrm->time.tm_wday = -1;
+        alrm->time.tm_mday = bcd2bin(alarmvals[2] & 0x3f);
+        alrm->time.tm_mon  = -1;
+        alrm->time.tm_year = -1;
+
+        alrm->enabled = !!(rv8803->ctrl & RV8803_CTRL_AIE);
+        alrm->pending = (flags & RV8803_FLAG_AF) && alrm->enabled;
+
+        return 0;
+}
+
+static int rv8803_set_alarm(struct device *dev, struct rtc_wkalrm *alrm)
+{
+        struct i2c_client *client = to_i2c_client(dev);
+        struct rv8803_data *rv8803 = dev_get_drvdata(dev);
+        u8 alarmvals[3];
+        u8 ctrl[2];
+        int ret, err;
+        unsigned long irqflags;
+
+        /* The alarm has no seconds, round up to nearest minute */
+        if (alrm->time.tm_sec) {
+                time64_t alarm_time = rtc_tm_to_time64(&alrm->time);
+
+                alarm_time += 60 - alrm->time.tm_sec;
+                rtc_time64_to_tm(alarm_time, &alrm->time);
+        }
+
+        spin_lock_irqsave(&rv8803->flags_lock, irqflags);
+
+        ret = i2c_smbus_read_i2c_block_data(client, RV8803_FLAG, 2, ctrl);
+        if (ret != 2) {
+                spin_unlock_irqrestore(&rv8803->flags_lock, irqflags);
+                return ret < 0 ? ret : -EIO;
+        }
+
+        alarmvals[0] = bin2bcd(alrm->time.tm_min);
+        alarmvals[1] = bin2bcd(alrm->time.tm_hour);
+        alarmvals[2] = bin2bcd(alrm->time.tm_mday);
+
+        if (rv8803->ctrl & (RV8803_CTRL_AIE | RV8803_CTRL_UIE)) {
+                rv8803->ctrl &= ~(RV8803_CTRL_AIE | RV8803_CTRL_UIE);
+                err = i2c_smbus_write_byte_data(rv8803->client, RV8803_CTRL,
+                                                rv8803->ctrl);
+                if (err) {
+                        spin_unlock_irqrestore(&rv8803->flags_lock, irqflags);
+                        return err;
+                }
+        }
+
+        ctrl[1] &= ~RV8803_FLAG_AF;
+        err = i2c_smbus_write_byte_data(rv8803->client, RV8803_FLAG, ctrl[1]);
+        spin_unlock_irqrestore(&rv8803->flags_lock, irqflags);
+        if (err)
+                return err;
+
+        err = i2c_smbus_write_i2c_block_data(rv8803->client, RV8803_ALARM_MIN,
+                                             3, alarmvals);
+        if (err)
+                return err;
+
+        if (alrm->enabled) {
+                if (rv8803->rtc->uie_rtctimer.enabled)
+                        rv8803->ctrl |= RV8803_CTRL_UIE;
+                if (rv8803->rtc->aie_timer.enabled)
+                        rv8803->ctrl |= RV8803_CTRL_AIE;
+
+                err = i2c_smbus_write_byte_data(rv8803->client, RV8803_CTRL,
+                                                rv8803->ctrl);
+                if (err)
+                        return err;
+        }
+
+        return 0;
+}
+
+static int rv8803_alarm_irq_enable(struct device *dev, unsigned int enabled)
+{
+        struct i2c_client *client = to_i2c_client(dev);
+        struct rv8803_data *rv8803 = dev_get_drvdata(dev);
+        int ctrl, flags, err;
+        unsigned long irqflags;
+
+        ctrl = rv8803->ctrl;
+
+        if (enabled) {
+                if (rv8803->rtc->uie_rtctimer.enabled)
+                        ctrl |= RV8803_CTRL_UIE;
+                if (rv8803->rtc->aie_timer.enabled)
+                        ctrl |= RV8803_CTRL_AIE;
+        } else {
+                if (!rv8803->rtc->uie_rtctimer.enabled)
+                        ctrl &= ~RV8803_CTRL_UIE;
+                if (!rv8803->rtc->aie_timer.enabled)
+                        ctrl &= ~RV8803_CTRL_AIE;
+        }
+
+        spin_lock_irqsave(&rv8803->flags_lock, irqflags);
+        flags = i2c_smbus_read_byte_data(client, RV8803_FLAG);
+        if (flags < 0) {
+                spin_unlock_irqrestore(&rv8803->flags_lock, irqflags);
+                return flags;
+        }
+        flags &= ~(RV8803_FLAG_AF | RV8803_FLAG_UF);
+        err = i2c_smbus_write_byte_data(client, RV8803_FLAG, flags);
+        spin_unlock_irqrestore(&rv8803->flags_lock, irqflags);
+        if (err)
+                return err;
+
+        if (ctrl != rv8803->ctrl) {
+                rv8803->ctrl = ctrl;
+                err = i2c_smbus_write_byte_data(client, RV8803_CTRL,
+                                                rv8803->ctrl);
+                if (err)
+                        return err;
+        }
+
+        return 0;
+}
+
+static int rv8803_ioctl(struct device *dev, unsigned int cmd, unsigned long arg)
+{
+        struct i2c_client *client = to_i2c_client(dev);
+        struct rv8803_data *rv8803 = dev_get_drvdata(dev);
+        int flags, ret = 0;
+        unsigned long irqflags;
+
+        switch (cmd) {
+        case RTC_VL_READ:
+                flags = i2c_smbus_read_byte_data(client, RV8803_FLAG);
+                if (flags < 0)
+                        return flags;
+
+                if (flags & RV8803_FLAG_V1F)
+                        dev_warn(&client->dev, "Voltage low, temperature compensation stopped.\n");
+
+                if (flags & RV8803_FLAG_V2F)
+                        dev_warn(&client->dev, "Voltage low, data loss detected.\n");
+
+                flags &= RV8803_FLAG_V1F | RV8803_FLAG_V2F;
+
+                if (copy_to_user((void __user *)arg, &flags, sizeof(int)))
+                        return -EFAULT;
+
+                return 0;
+
+        case RTC_VL_CLR:
+                spin_lock_irqsave(&rv8803->flags_lock, irqflags);
+                flags = i2c_smbus_read_byte_data(client, RV8803_FLAG);
+                if (flags < 0) {
+                        spin_unlock_irqrestore(&rv8803->flags_lock, irqflags);
+                        return flags;
+                }
+
+                flags &= ~(RV8803_FLAG_V1F | RV8803_FLAG_V2F);
+                ret = i2c_smbus_write_byte_data(client, RV8803_FLAG, flags);
+                spin_unlock_irqrestore(&rv8803->flags_lock, irqflags);
+                if (ret < 0)
+                        return ret;
+
+                return 0;
+
+        default:
+                return -ENOIOCTLCMD;
+        }
+}
+
+static ssize_t rv8803_nvram_write(struct file *filp, struct kobject *kobj,
+                                  struct bin_attribute *attr,
+                                  char *buf, loff_t off, size_t count)
+{
+        struct device *dev = kobj_to_dev(kobj);
+        struct i2c_client *client = to_i2c_client(dev);
+        int ret;
+
+        ret = i2c_smbus_write_byte_data(client, RV8803_RAM, buf[0]);
+        if (ret < 0)
+                return ret;
+
+        return 1;
+}
+
+static ssize_t rv8803_nvram_read(struct file *filp, struct kobject *kobj,
+                                 struct bin_attribute *attr,
+                                 char *buf, loff_t off, size_t count)
+{
+        struct device *dev = kobj_to_dev(kobj);
+        struct i2c_client *client = to_i2c_client(dev);
+        int ret;
+
+        ret = i2c_smbus_read_byte_data(client, RV8803_RAM);
+        if (ret < 0)
+                return ret;
+
+        buf[0] = ret;
+
+        return 1;
+}
+
+static struct bin_attribute rv8803_nvram_attr = {
+        .attr = {
+                .name = "nvram",
+                .mode = S_IRUGO | S_IWUSR,
+        },
+        .size = 1,
+        .read = rv8803_nvram_read,
+        .write = rv8803_nvram_write,
+};
+
+static struct rtc_class_ops rv8803_rtc_ops = {
+        .read_time = rv8803_get_time,
+        .set_time = rv8803_set_time,
+        .ioctl = rv8803_ioctl,
+};
+
+static int rv8803_probe(struct i2c_client *client,
+                        const struct i2c_device_id *id)
+{
+        struct i2c_adapter *adapter = to_i2c_adapter(client->dev.parent);
+        struct rv8803_data *rv8803;
+        int err, flags;
+
+        if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA |
+                                     I2C_FUNC_SMBUS_I2C_BLOCK)) {
+                dev_err(&adapter->dev, "doesn't support I2C_FUNC_SMBUS_BYTE_DATA | I2C_FUNC_SMBUS_I2C_BLOCK\n");
+                return -EIO;
+        }
+
+        rv8803 = devm_kzalloc(&client->dev, sizeof(struct rv8803_data),
+                              GFP_KERNEL);
+        if (!rv8803)
+                return -ENOMEM;
+
+        rv8803->client = client;
+        i2c_set_clientdata(client, rv8803);
+
+        flags = i2c_smbus_read_byte_data(client, RV8803_FLAG);
+        if (flags < 0)
+                return flags;
+
+        if (flags & RV8803_FLAG_V1F)
+                dev_warn(&client->dev, "Voltage low, temperature compensation stopped.\n");
+
+        if (flags & RV8803_FLAG_V2F)
+                dev_warn(&client->dev, "Voltage low, data loss detected.\n");
+
+        if (flags & RV8803_FLAG_AF)
+                dev_warn(&client->dev, "An alarm maybe have been missed.\n");
+
+        if (client->irq > 0) {
+                err = devm_request_threaded_irq(&client->dev, client->irq,
+                                                NULL, rv8803_handle_irq,
+                                                IRQF_TRIGGER_LOW | IRQF_ONESHOT,
+                                                "rv8803", client);
+                if (err) {
+                        dev_warn(&client->dev, "unable to request IRQ, alarms disabled\n");
+                        client->irq = 0;
+                } else {
+                        rv8803_rtc_ops.read_alarm = rv8803_get_alarm;
+                        rv8803_rtc_ops.set_alarm = rv8803_set_alarm;
+                        rv8803_rtc_ops.alarm_irq_enable = rv8803_alarm_irq_enable;
+                }
+        }
+
+        rv8803->rtc = devm_rtc_device_register(&client->dev, client->name,
+                                               &rv8803_rtc_ops, THIS_MODULE);
+        if (IS_ERR(rv8803->rtc)) {
+                dev_err(&client->dev, "unable to register the class device\n");
+                return PTR_ERR(rv8803->rtc);
+        }
+
+        err = i2c_smbus_write_byte_data(rv8803->client, RV8803_EXT,
+                                        RV8803_EXT_WADA);
+        if (err)
+                return err;
+
+        err = device_create_bin_file(&client->dev, &rv8803_nvram_attr);
+        if (err)
+                return err;
+
+        rv8803->rtc->max_user_freq = 1;
+
+        return 0;
+}
+
+static int rv8803_remove(struct i2c_client *client)
+{
+        device_remove_bin_file(&client->dev, &rv8803_nvram_attr);
+
+        return 0;
+}
+
+static const struct i2c_device_id rv8803_id[] = {
+        { "rv8803", 0 },
+        { }
+};
+MODULE_DEVICE_TABLE(i2c, rv8803_id);
+
+static struct i2c_driver rv8803_driver = {
+        .driver = {
+                .name = "rtc-rv8803",
+        },
+        .probe          = rv8803_probe,
+        .remove         = rv8803_remove,
+        .id_table       = rv8803_id,
+};
+module_i2c_driver(rv8803_driver);
+
+MODULE_AUTHOR("Alexandre Belloni <alexandre.belloni@free-electrons.com>");
+MODULE_DESCRIPTION("Micro Crystal RV8803 RTC driver");
+MODULE_LICENSE("GPL v2");