rtc: add support for the S-35390A RTC chip

This adds basic get/set time support for the Seiko Instruments S-35390A.
This chip communicates using I2C and is used on the QNAP TS-109/TS-209 NAS
devices.

[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: Byron Bradley <byron.bbradley@gmail.com>
Acked-by: Jean Delvare <khali@linux-fr.org>
Acked-by: David Brownell <david-b@pacbell.net>
Tested-by: Tim Ellis <tim@ngndg.com>
Cc: Alessandro Zummo <a.zummo@towertech.it>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

3 files changed, 326 insertions, 0 deletions

diff --git a/drivers/rtc/Kconfig b/drivers/rtc/Kconfig
index 6402d699072b..82f5ad9c3af4 100644
--- a/drivers/rtc/Kconfig
+++ b/drivers/rtc/Kconfig
@@ -250,6 +250,15 @@ config RTC_DRV_TWL92330
           platforms.  The support is integrated with the rest of
           the Menelaus driver; it's not separate module.
 
+config RTC_DRV_S35390A
+        tristate "Seiko Instruments S-35390A"
+        help
+          If you say yes here you will get support for the Seiko
+          Instruments S-35390A.
+
+          This driver can also be built as a module. If so the module
+          will be called rtc-s35390a.
+
 endif # I2C
 
 comment "SPI RTC drivers"
diff --git a/drivers/rtc/Makefile b/drivers/rtc/Makefile
index ec703f34ab86..872f1218ff9f 100644
--- a/drivers/rtc/Makefile
+++ b/drivers/rtc/Makefile
@@ -45,6 +45,7 @@ obj-$(CONFIG_RTC_DRV_R9701)	+= rtc-r9701.o
 obj-$(CONFIG_RTC_DRV_RS5C313)   += rtc-rs5c313.o
 obj-$(CONFIG_RTC_DRV_RS5C348)   += rtc-rs5c348.o
 obj-$(CONFIG_RTC_DRV_RS5C372)   += rtc-rs5c372.o
+obj-$(CONFIG_RTC_DRV_S35390A)   += rtc-s35390a.o
 obj-$(CONFIG_RTC_DRV_S3C)       += rtc-s3c.o
 obj-$(CONFIG_RTC_DRV_SA1100)    += rtc-sa1100.o
 obj-$(CONFIG_RTC_DRV_SH)        += rtc-sh.o
diff --git a/drivers/rtc/rtc-s35390a.c b/drivers/rtc/rtc-s35390a.c
new file mode 100644
index 000000000000..e8abc90c32c5
--- /dev/null
+++ b/drivers/rtc/rtc-s35390a.c
@@ -0,0 +1,316 @@
+/*
+ * Seiko Instruments S-35390A RTC Driver
+ *
+ * Copyright (c) 2007 Byron Bradley
+ *
+ * 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.
+ */
+
+#include <linux/module.h>
+#include <linux/rtc.h>
+#include <linux/i2c.h>
+#include <linux/bitrev.h>
+#include <linux/bcd.h>
+#include <linux/slab.h>
+
+#define S35390A_CMD_STATUS1     0
+#define S35390A_CMD_STATUS2     1
+#define S35390A_CMD_TIME1       2
+
+#define S35390A_BYTE_YEAR       0
+#define S35390A_BYTE_MONTH      1
+#define S35390A_BYTE_DAY        2
+#define S35390A_BYTE_WDAY       3
+#define S35390A_BYTE_HOURS      4
+#define S35390A_BYTE_MINS       5
+#define S35390A_BYTE_SECS       6
+
+#define S35390A_FLAG_POC        0x01
+#define S35390A_FLAG_BLD        0x02
+#define S35390A_FLAG_24H        0x40
+#define S35390A_FLAG_RESET      0x80
+#define S35390A_FLAG_TEST       0x01
+
+struct s35390a {
+        struct i2c_client *client[8];
+        struct rtc_device *rtc;
+        int twentyfourhour;
+};
+
+static int s35390a_set_reg(struct s35390a *s35390a, int reg, char *buf, int len)
+{
+        struct i2c_client *client = s35390a->client[reg];
+        struct i2c_msg msg[] = {
+                { client->addr, 0, len, buf },
+        };
+
+        if ((i2c_transfer(client->adapter, msg, 1)) != 1)
+                return -EIO;
+
+        return 0;
+}
+
+static int s35390a_get_reg(struct s35390a *s35390a, int reg, char *buf, int len)
+{
+        struct i2c_client *client = s35390a->client[reg];
+        struct i2c_msg msg[] = {
+                { client->addr, I2C_M_RD, len, buf },
+        };
+
+        if ((i2c_transfer(client->adapter, msg, 1)) != 1)
+                return -EIO;
+
+        return 0;
+}
+
+static int s35390a_reset(struct s35390a *s35390a)
+{
+        char buf[1];
+
+        if (s35390a_get_reg(s35390a, S35390A_CMD_STATUS1, buf, sizeof(buf)) < 0)
+                return -EIO;
+
+        if (!(buf[0] & (S35390A_FLAG_POC | S35390A_FLAG_BLD)))
+                return 0;
+
+        buf[0] |= (S35390A_FLAG_RESET | S35390A_FLAG_24H);
+        buf[0] &= 0xf0;
+        return s35390a_set_reg(s35390a, S35390A_CMD_STATUS1, buf, sizeof(buf));
+}
+
+static int s35390a_disable_test_mode(struct s35390a *s35390a)
+{
+        char buf[1];
+
+        if (s35390a_get_reg(s35390a, S35390A_CMD_STATUS2, buf, sizeof(buf)) < 0)
+                return -EIO;
+
+        if (!(buf[0] & S35390A_FLAG_TEST))
+                return 0;
+
+        buf[0] &= ~S35390A_FLAG_TEST;
+        return s35390a_set_reg(s35390a, S35390A_CMD_STATUS2, buf, sizeof(buf));
+}
+
+static char s35390a_hr2reg(struct s35390a *s35390a, int hour)
+{
+        if (s35390a->twentyfourhour)
+                return BIN2BCD(hour);
+
+        if (hour < 12)
+                return BIN2BCD(hour);
+
+        return 0x40 | BIN2BCD(hour - 12);
+}
+
+static int s35390a_reg2hr(struct s35390a *s35390a, char reg)
+{
+        unsigned hour;
+
+        if (s35390a->twentyfourhour)
+                return BCD2BIN(reg & 0x3f);
+
+        hour = BCD2BIN(reg & 0x3f);
+        if (reg & 0x40)
+                hour += 12;
+
+        return hour;
+}
+
+static int s35390a_set_datetime(struct i2c_client *client, struct rtc_time *tm)
+{
+        struct s35390a  *s35390a = i2c_get_clientdata(client);
+        int i, err;
+        char buf[7];
+
+        dev_dbg(&client->dev, "%s: tm is secs=%d, mins=%d, hours=%d mday=%d, "
+                "mon=%d, year=%d, wday=%d\n", __func__, tm->tm_sec,
+                tm->tm_min, tm->tm_hour, tm->tm_mday, tm->tm_mon, tm->tm_year,
+                tm->tm_wday);
+
+        buf[S35390A_BYTE_YEAR] = BIN2BCD(tm->tm_year - 100);
+        buf[S35390A_BYTE_MONTH] = BIN2BCD(tm->tm_mon + 1);
+        buf[S35390A_BYTE_DAY] = BIN2BCD(tm->tm_mday);
+        buf[S35390A_BYTE_WDAY] = BIN2BCD(tm->tm_wday);
+        buf[S35390A_BYTE_HOURS] = s35390a_hr2reg(s35390a, tm->tm_hour);
+        buf[S35390A_BYTE_MINS] = BIN2BCD(tm->tm_min);
+        buf[S35390A_BYTE_SECS] = BIN2BCD(tm->tm_sec);
+
+        /* This chip expects the bits of each byte to be in reverse order */
+        for (i = 0; i < 7; ++i)
+                buf[i] = bitrev8(buf[i]);
+
+        err = s35390a_set_reg(s35390a, S35390A_CMD_TIME1, buf, sizeof(buf));
+
+        return err;
+}
+
+static int s35390a_get_datetime(struct i2c_client *client, struct rtc_time *tm)
+{
+        struct s35390a *s35390a = i2c_get_clientdata(client);
+        char buf[7];
+        int i, err;
+
+        err = s35390a_get_reg(s35390a, S35390A_CMD_TIME1, buf, sizeof(buf));
+        if (err < 0)
+                return err;
+
+        /* This chip returns the bits of each byte in reverse order */
+        for (i = 0; i < 7; ++i)
+                buf[i] = bitrev8(buf[i]);
+
+        tm->tm_sec = BCD2BIN(buf[S35390A_BYTE_SECS]);
+        tm->tm_min = BCD2BIN(buf[S35390A_BYTE_MINS]);
+        tm->tm_hour = s35390a_reg2hr(s35390a, buf[S35390A_BYTE_HOURS]);
+        tm->tm_wday = BCD2BIN(buf[S35390A_BYTE_WDAY]);
+        tm->tm_mday = BCD2BIN(buf[S35390A_BYTE_DAY]);
+        tm->tm_mon = BCD2BIN(buf[S35390A_BYTE_MONTH]) - 1;
+        tm->tm_year = BCD2BIN(buf[S35390A_BYTE_YEAR]) + 100;
+
+        dev_dbg(&client->dev, "%s: tm is secs=%d, mins=%d, hours=%d, mday=%d, "
+                "mon=%d, year=%d, wday=%d\n", __func__, tm->tm_sec,
+                tm->tm_min, tm->tm_hour, tm->tm_mday, tm->tm_mon, tm->tm_year,
+                tm->tm_wday);
+
+        return rtc_valid_tm(tm);
+}
+
+static int s35390a_rtc_read_time(struct device *dev, struct rtc_time *tm)
+{
+        return s35390a_get_datetime(to_i2c_client(dev), tm);
+}
+
+static int s35390a_rtc_set_time(struct device *dev, struct rtc_time *tm)
+{
+        return s35390a_set_datetime(to_i2c_client(dev), tm);
+}
+
+static const struct rtc_class_ops s35390a_rtc_ops = {
+        .read_time      = s35390a_rtc_read_time,
+        .set_time       = s35390a_rtc_set_time,
+};
+
+static struct i2c_driver s35390a_driver;
+
+static int s35390a_probe(struct i2c_client *client)
+{
+        int err;
+        unsigned int i;
+        struct s35390a *s35390a;
+        struct rtc_time tm;
+        char buf[1];
+
+        if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C)) {
+                err = -ENODEV;
+                goto exit;
+        }
+
+        s35390a = kzalloc(sizeof(struct s35390a), GFP_KERNEL);
+        if (!s35390a) {
+                err = -ENOMEM;
+                goto exit;
+        }
+
+        s35390a->client[0] = client;
+        i2c_set_clientdata(client, s35390a);
+
+        /* This chip uses multiple addresses, use dummy devices for them */
+        for (i = 1; i < 8; ++i) {
+                s35390a->client[i] = i2c_new_dummy(client->adapter,
+                                        client->addr + i, "rtc-s35390a");
+                if (!s35390a->client[i]) {
+                        dev_err(&client->dev, "Address %02x unavailable\n",
+                                                client->addr + i);
+                        err = -EBUSY;
+                        goto exit_dummy;
+                }
+        }
+
+        err = s35390a_reset(s35390a);
+        if (err < 0) {
+                dev_err(&client->dev, "error resetting chip\n");
+                goto exit_dummy;
+        }
+
+        err = s35390a_disable_test_mode(s35390a);
+        if (err < 0) {
+                dev_err(&client->dev, "error disabling test mode\n");
+                goto exit_dummy;
+        }
+
+        err = s35390a_get_reg(s35390a, S35390A_CMD_STATUS1, buf, sizeof(buf));
+        if (err < 0) {
+                dev_err(&client->dev, "error checking 12/24 hour mode\n");
+                goto exit_dummy;
+        }
+        if (buf[0] & S35390A_FLAG_24H)
+                s35390a->twentyfourhour = 1;
+        else
+                s35390a->twentyfourhour = 0;
+
+        if (s35390a_get_datetime(client, &tm) < 0)
+                dev_warn(&client->dev, "clock needs to be set\n");
+
+        s35390a->rtc = rtc_device_register(s35390a_driver.driver.name,
+                                &client->dev, &s35390a_rtc_ops, THIS_MODULE);
+
+        if (IS_ERR(s35390a->rtc)) {
+                err = PTR_ERR(s35390a->rtc);
+                goto exit_dummy;
+        }
+        return 0;
+
+exit_dummy:
+        for (i = 1; i < 8; ++i)
+                if (s35390a->client[i])
+                        i2c_unregister_device(s35390a->client[i]);
+        kfree(s35390a);
+        i2c_set_clientdata(client, NULL);
+
+exit:
+        return err;
+}
+
+static int s35390a_remove(struct i2c_client *client)
+{
+        unsigned int i;
+
+        struct s35390a *s35390a = i2c_get_clientdata(client);
+        for (i = 1; i < 8; ++i)
+                if (s35390a->client[i])
+                        i2c_unregister_device(s35390a->client[i]);
+
+        rtc_device_unregister(s35390a->rtc);
+        kfree(s35390a);
+        i2c_set_clientdata(client, NULL);
+
+        return 0;
+}
+
+static struct i2c_driver s35390a_driver = {
+        .driver         = {
+                .name   = "rtc-s35390a",
+        },
+        .probe          = s35390a_probe,
+        .remove         = s35390a_remove,
+};
+
+static int __init s35390a_rtc_init(void)
+{
+        return i2c_add_driver(&s35390a_driver);
+}
+
+static void __exit s35390a_rtc_exit(void)
+{
+        i2c_del_driver(&s35390a_driver);
+}
+
+MODULE_AUTHOR("Byron Bradley <byron.bbradley@gmail.com>");
+MODULE_DESCRIPTION("S35390A RTC driver");
+MODULE_LICENSE("GPL");
+
+module_init(s35390a_rtc_init);
+module_exit(s35390a_rtc_exit);