This is a patch to add support for
maxim dallas rtc max6917.

Signed-off-by: Venkat Prashanth B U <venkat.prashanth2...@gmail.com>
---
---
 drivers/rtc/Kconfig       |   9 +
 drivers/rtc/Makefile      |   1 +
 drivers/rtc/rtc-max6917.c | 406 ++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 416 insertions(+)

diff --git a/drivers/rtc/Kconfig b/drivers/rtc/Kconfig
index e215f50..2163606 100644
--- a/drivers/rtc/Kconfig
+++ b/drivers/rtc/Kconfig
@@ -277,6 +277,15 @@ config RTC_DRV_MAX6900
          This driver can also be built as a module. If so, the module
          will be called rtc-max6900.
 
+config RTC_DRV_MAX6917
+       tristate "Maxim MAX6917"
+       help
+         If you say yes here you will get support for the
+         Maxim MAX6917 I2C RTC chip.
+
+         This driver can also be built as a module. If so, the module
+         will be called rtc-max6917.
+
 config RTC_DRV_MAX8907
        tristate "Maxim MAX8907"
        depends on MFD_MAX8907
diff --git a/drivers/rtc/Makefile b/drivers/rtc/Makefile
index 7cf7ad5..29332fb 100644
--- a/drivers/rtc/Makefile
+++ b/drivers/rtc/Makefile
@@ -87,6 +87,7 @@ obj-$(CONFIG_RTC_DRV_M48T86)  += rtc-m48t86.o
 obj-$(CONFIG_RTC_DRV_MAX6900)  += rtc-max6900.o
 obj-$(CONFIG_RTC_DRV_MAX6902)  += rtc-max6902.o
 obj-$(CONFIG_RTC_DRV_MAX6916)  += rtc-max6916.o
+obj-$(CONFIG_RTC_DRV_MAX6917)  += rtc-max6917.o
 obj-$(CONFIG_RTC_DRV_MAX77686) += rtc-max77686.o
 obj-$(CONFIG_RTC_DRV_MAX8907)  += rtc-max8907.o
 obj-$(CONFIG_RTC_DRV_MAX8925)  += rtc-max8925.o
diff --git a/drivers/rtc/rtc-max6917.c b/drivers/rtc/rtc-max6917.c
index e69de29..1176384 100644
--- a/drivers/rtc/rtc-max6917.c
+++ b/drivers/rtc/rtc-max6917.c
@@ -0,0 +1,406 @@
+       /* rtc-max6917.c
+       *
+       * Driver for MAXIM  max6917  I2C-Compatible Real Time Clock
+       *
+       * Author : Venkat Prashanth B U <venkat.prashanth2...@gmail.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/i2c.h>
+       #include <linux/init.h>
+       #include <linux/module.h>
+       #include <linux/rtc.h>
+       #include <linux/string.h>
+       #include <linux/delay.h>
+       #include <linux/clk-provider.h>
+       #include <linux/slab.h>
+
+       #define MAX6917_REG_SECS                0x01    /* 00-59 */
+       #define MAX6917_REG_MIN                 0x02    /* 00-59 */
+       #define MAX6917_REG_HOUR                0x03    /* 00-23, or 
1-12{am,pm} */
+       #define MAX6917_REG_WDAY                0x04    /* 01-07 */
+       #define MAX6917_REG_MDAY                0x05    /* 01-31 */
+       #define MAX6917_REG_MONTH               0x06    /* 01-12 */
+       #define MAX6917_REG_YEAR                0x07    /* 00-99 */
+       #define MAX6917_REG_CONTROL             0x08
+       #define MAX6917_REG_STATUS              0x0c
+       #define MAX6917_REG_ALARM               0x0a
+       #define MAX6917_BURST_LEN               8       /* can burst r/w first 
8 regs */
+       #define MAX6917_REG_CENTURY             9       /* century */
+       #define MAX6917_REG_LEN                 10
+       #define MAX6917_REG_CT_WP               (1 << 7)        /* Write 
Protect */
+       /*
+       * register read/write commands
+       */
+       #define MAX6917_REG_CONTROL_WRITE       0x8e
+       #define MAX6917_REG_CENTURY_WRITE       0x92
+       #define MAX6917_REG_CENTURY_READ        0x93
+       #define MAX6917_REG_RESERVED_READ       0x96
+       #define MAX6917_REG_BURST_WRITE         0xbe
+       #define MAX6917_REG_BURST_READ          0xbf
+
+       #define MAX6917_IDLE_TIME_AFTER_WRITE   3       /* specification says 
2.5 mS */
+
+       static struct i2c_driver max6917_driver;
+
+       struct max6917
+       {
+       u8 offset;                      /* register's offset */
+       u8 regs[11];
+       u16 nvram_offset;
+       struct bin_attribute *nvram;
+       unsigned long flags;
+       #define HAS_NVRAM                       0       /* bit 0 == sysfs file 
active */
+       #define HAS_ALARM                       1       /* bit 1 == irq claimed 
*/
+       struct i2c_client *client;
+       struct rtc_device *rtc;
+               s32 (*read_block_data) (const struct i2c_client * client, u8 
command,
+                                       u8 length, u8 * values);
+               s32 (*write_block_data) (const struct i2c_client * client, u8 
command,
+                                       u8 length, const u8 * values);
+       };
+
+       struct chip_desc
+       {
+       unsigned alarm:1;
+       u16 nvram_offset;
+       u16 nvram_size;
+       };
+
+       static int
+       max6917_i2c_read_regs (struct i2c_client *client, u8 * buf)
+       {
+       u8 reg_burst_read[1] = { MAX6917_REG_BURST_READ };
+       u8 reg_century_read[1] = { MAX6917_REG_CENTURY_READ };
+       struct i2c_msg msgs[4] = {
+               {
+               .addr = client->addr,
+               .flags = 0,             /* write */
+               .len = sizeof (reg_burst_read),
+               .buf = reg_burst_read}
+               ,
+               {
+               .addr = client->addr,
+               .flags = I2C_M_RD,
+               .len = MAX6917_BURST_LEN,
+               .buf = buf}
+               ,
+               {
+               .addr = client->addr,
+               .flags = 0,             /* write */
+               .len = sizeof (reg_century_read),
+               .buf = reg_century_read}
+               ,
+               {
+               .addr = client->addr,
+               .flags = I2C_M_RD,
+               .len = sizeof (buf[MAX6917_REG_CENTURY]),
+               .buf = &buf[MAX6917_REG_CENTURY]}
+       };
+       int rc;
+
+       rc = i2c_transfer (client->adapter, msgs, ARRAY_SIZE (msgs));
+       if (rc != ARRAY_SIZE (msgs))
+               {
+                       dev_err (&client->dev, "%s: register read failed\n", 
__func__);
+                       return -EIO;
+               }
+       return 0;
+       }
+
+       static int
+       max6917_i2c_write_regs (struct i2c_client *client, u8 const *buf)
+       {
+       u8 i2c_century_buf[1 + 1] = { MAX6917_REG_CENTURY_WRITE };
+       struct i2c_msg century_msgs[1] = {
+               {
+               .addr = client->addr,
+               .flags = 0,             /* write */
+               .len = sizeof (i2c_century_buf),
+               .buf = i2c_century_buf}
+       };
+       u8 i2c_burst_buf[MAX6917_BURST_LEN + 1] = { MAX6917_REG_BURST_WRITE };
+       struct i2c_msg burst_msgs[1] = {
+               {
+               .addr = client->addr,
+               .flags = 0,             /* write */
+               .len = sizeof (i2c_burst_buf),
+               .buf = i2c_burst_buf}
+       };
+       int rc;
+
+       /*
+               * We have to make separate calls to i2c_transfer because of
+               * the need to delay after each write to the chip.  Also,
+               * we write the century byte first, since we set the 
write-protect
+               * bit as part of the burst write.
+               */
+       i2c_century_buf[1] = buf[MAX6917_REG_CENTURY];
+
+       rc = i2c_transfer (client->adapter, century_msgs,
+                               ARRAY_SIZE (century_msgs));
+       if (rc != ARRAY_SIZE (century_msgs))
+               goto write_failed;
+
+       msleep (MAX6917_IDLE_TIME_AFTER_WRITE);
+
+       memcpy (&i2c_burst_buf[1], buf, MAX6917_BURST_LEN);
+
+       rc = i2c_transfer (client->adapter, burst_msgs, ARRAY_SIZE 
(burst_msgs));
+       if (rc != ARRAY_SIZE (burst_msgs))
+               goto write_failed;
+       msleep (MAX6917_IDLE_TIME_AFTER_WRITE);
+
+       return 0;
+
+       write_failed:
+       dev_err (&client->dev, "%s: register write failed\n", __func__);
+       return -EIO;
+       }
+
+       static int
+       max6917_i2c_read_time (struct i2c_client *client, struct rtc_time *tm)
+       {
+       int rc;
+       u8 regs[MAX6917_REG_LEN];
+
+       rc = max6917_i2c_read_regs (client, regs);
+       if (rc < 0)
+               return rc;
+
+       tm->tm_sec = bcd2bin (regs[MAX6917_REG_SECS]);
+       tm->tm_min = bcd2bin (regs[MAX6917_REG_MIN]);
+       tm->tm_hour = bcd2bin (regs[MAX6917_REG_HOUR] & 0x3f);
+       tm->tm_mday = bcd2bin (regs[MAX6917_REG_MDAY]);
+       tm->tm_mon = bcd2bin (regs[MAX6917_REG_MONTH]) - 1;
+       tm->tm_year = bcd2bin (regs[MAX6917_REG_YEAR]) +
+               bcd2bin (regs[MAX6917_REG_CENTURY]) * 100 - 1900;
+       tm->tm_wday = bcd2bin (regs[MAX6917_REG_WDAY]);
+
+       return rtc_valid_tm (tm);
+       }
+
+       static int
+       max6917_i2c_clear_write_protect (struct i2c_client *client)
+       {
+       return i2c_smbus_write_byte_data (client, MAX6917_REG_CONTROL_WRITE, 0);
+       }
+
+       static int
+       max6917_i2c_set_time (struct i2c_client *client, struct rtc_time const 
*tm)
+       {
+       u8 regs[MAX6917_REG_LEN];
+       int rc;
+
+       rc = max6917_i2c_clear_write_protect (client);
+       if (rc < 0)
+               return rc;
+
+       regs[MAX6917_REG_SECS] = bin2bcd (tm->tm_sec);
+       regs[MAX6917_REG_MIN] = bin2bcd (tm->tm_min);
+       regs[MAX6917_REG_HOUR] = bin2bcd (tm->tm_hour);
+       regs[MAX6917_REG_MDAY] = bin2bcd (tm->tm_mday);
+       regs[MAX6917_REG_MONTH] = bin2bcd (tm->tm_mon + 1);
+       regs[MAX6917_REG_WDAY] = bin2bcd (tm->tm_wday);
+       regs[MAX6917_REG_YEAR] = bin2bcd (tm->tm_year % 100);
+       regs[MAX6917_REG_CENTURY] = bin2bcd ((tm->tm_year + 1900) / 100);
+       /* set write protect */
+       regs[MAX6917_REG_CONTROL] = MAX6917_REG_CT_WP;
+
+       rc = max6917_i2c_write_regs (client, regs);
+       if (rc < 0)
+               return rc;
+
+       return 0;
+       }
+
+       static int
+       max6917_rtc_read_time (struct device *dev, struct rtc_time *tm)
+       {
+       return max6917_i2c_read_time (to_i2c_client (dev), tm);
+       }
+
+       static int
+       max6917_rtc_set_time (struct device *dev, struct rtc_time *tm)
+       {
+       return max6917_i2c_set_time (to_i2c_client (dev), tm);
+       }
+
+       static int
+       max6917_read_alarm (struct device *dev, struct rtc_wkalrm *t)
+       {
+       struct i2c_client *client = to_i2c_client (dev);
+       struct max6917 *max6917 = i2c_get_clientdata (client);
+       int ret;
+
+       if (!test_bit (HAS_ALARM, &max6917->flags))
+               return -EINVAL;
+
+       /* read all ALARM1, ALARM2, and status registers at once */
+       ret = max6917->read_block_data (client,
+                                       MAX6917_REG_ALARM, 9, max6917->regs);
+       if (ret != 9)
+               {
+                       dev_err (dev, " error %d\n", "alarm read", ret);
+                       return -EIO;
+               }
+
+       dev_dbg (dev, "%4ph, %3ph, %2ph\n", "alarm read",
+                       &max6917->regs[0], &max6917->regs[4], 
&max6917->regs[7]);
+
+       /*
+               * report alarm time (ALARM1); assume 24 hour and day-of-month 
modes,
+               * and that all four fields are checked matches
+               */
+       t->time.tm_sec = bcd2bin (max6917->regs[0] & 0x7f);
+       t->time.tm_min = bcd2bin (max6917->regs[1] & 0x7f);
+       t->time.tm_hour = bcd2bin (max6917->regs[2] & 0x3f);
+       t->time.tm_mday = bcd2bin (max6917->regs[3] & 0x3f);
+
+       dev_dbg (dev, " %s secs=%d, mins=%d, "
+                       "hours=%d, mday=%d, enabled=%d, pending=%d\n",
+                       "alarm read", t->time.tm_sec, t->time.tm_min,
+                       t->time.tm_hour, t->time.tm_mday);
+
+       return 0;
+       }
+
+       static int
+       max6917_set_alarm (struct device *dev, struct rtc_wkalrm *t)
+       {
+       struct i2c_client *client = to_i2c_client (dev);
+       struct max6917 *max6917 = i2c_get_clientdata (client);
+       unsigned char *buf = max6917->regs;
+       u8 control, status;
+       int ret;
+
+       if (!test_bit (HAS_ALARM, &max6917->flags))
+               return -EINVAL;
+
+       dev_dbg (dev, " %s secs=%d, mins=%d, "
+                       "hours=%d, mday=%d, enabled=%d, pending=%d\n",
+                       "alarm set", t->time.tm_sec, t->time.tm_min,
+                       t->time.tm_hour, t->time.tm_mday);
+
+       /* read current status of both alarms and the chip */
+       ret = max6917->read_block_data (client, MAX6917_REG_ALARM, 9, buf);
+       if (ret != 9)
+               {
+                       dev_err (dev, "%s error %d\n", "alarm write", ret);
+                       return -EIO;
+               }
+       control = max6917->regs[7];
+       status = max6917->regs[8];
+
+       dev_dbg (dev, "%s: %4ph, %3ph, %02x %02x\n", "alarm set (old status)",
+                       &max6917->regs[0], &max6917->regs[4], control, status);
+
+       /* set ALARM1, using 24 hour and day-of-month modes */
+       buf[0] = bin2bcd (t->time.tm_sec);
+       buf[1] = bin2bcd (t->time.tm_min);
+       buf[2] = bin2bcd (t->time.tm_hour);
+       buf[3] = bin2bcd (t->time.tm_mday);
+       buf[4] = 0;
+       buf[5] = 0;
+       buf[6] = 0;
+
+       ret = max6917->write_block_data (client, MAX6917_REG_ALARM, 9, buf);
+       if (ret < 0)
+               {
+                       dev_err (dev, "can't set alarm time\n");
+                       return ret;
+               }
+       return 0;
+       }
+
+       static ssize_t
+       max6917_nvram_read (struct file *filp, struct kobject *kobj,
+                               struct bin_attribute *attr,
+                               char *buf, loff_t off, size_t count)
+       {
+       struct i2c_client *client;
+       struct max6917 *max6917;
+       int result;
+
+       client = kobj_to_i2c_client (kobj);
+       max6917 = i2c_get_clientdata (client);
+
+       result = max6917->read_block_data (client, max6917->nvram_offset + off,
+                                               count, buf);
+       if (result < 0)
+               dev_err (&client->dev, "%s error %d\n", "nvram read", result);
+       return result;
+       }
+
+       static ssize_t
+       max6917_nvram_write (struct file *filp, struct kobject *kobj,
+                               struct bin_attribute *attr,
+                               char *buf, loff_t off, size_t count)
+       {
+       struct i2c_client *client;
+       struct max6917 *max6917;
+       int result;
+
+       client = kobj_to_i2c_client (kobj);
+       max6917 = i2c_get_clientdata (client);
+
+       result = max6917->write_block_data (client, max6917->nvram_offset + off,
+                                               count, buf);
+       if (result < 0)
+               {
+                       dev_err (&client->dev, "%s error %d\n", "nvram write", 
result);
+                       return result;
+               }
+       return count;
+       }
+
+       static const struct rtc_class_ops max6917_rtc_ops = {
+       .read_time = max6917_rtc_read_time,
+       .set_time = max6917_rtc_set_time,
+       .read_alarm = max6917_read_alarm,
+       .set_alarm = max6917_set_alarm,
+       };
+
+       static int
+       max6917_probe (struct i2c_client *client, const struct i2c_device_id 
*id)
+       {
+       struct rtc_device *rtc;
+
+       if (!i2c_check_functionality (client->adapter, I2C_FUNC_I2C))
+               return -ENODEV;
+
+       rtc = devm_rtc_device_register (&client->dev, 
max6917_driver.driver.name,
+                                       &max6917_rtc_ops, THIS_MODULE);
+       if (IS_ERR (rtc))
+               return PTR_ERR (rtc);
+
+       i2c_set_clientdata (client, rtc);
+
+       return 0;
+       }
+
+       static struct i2c_device_id max6917_id[] = {
+       {"max6917", 0},
+       {}
+       };
+
+       MODULE_DEVICE_TABLE (i2c, max6917_id);
+
+       static struct i2c_driver max6917_driver = {
+       .driver = {
+                       .name = "rtc-max6917",
+                       },
+       .probe = max6917_probe,
+       .id_table = max6917_id,
+       };
+
+       module_i2c_driver (max6917_driver);
+
+       MODULE_DESCRIPTION ("Maxim MAX6917 RTC driver");
+       MODULE_AUTHOR ("Venkat Prashanth B U");
+       MODULE_LICENSE ("GPL");
-- 
1.9.2

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