This is the patch to add support for
NXP rtc pca21125

Signed-off-by: Venkat Prashanth B U <venkat.prashanth2...@gmail.com>
---
---
 drivers/rtc/Kconfig        |  12 ++++
 drivers/rtc/Makefile       |   1 +
 drivers/rtc/rtc-pca21125.c | 164 +++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 177 insertions(+)

diff --git a/drivers/rtc/Kconfig b/drivers/rtc/Kconfig
index e215f50..df10e0e 100644
--- a/drivers/rtc/Kconfig
+++ b/drivers/rtc/Kconfig
@@ -686,6 +686,18 @@ config RTC_DRV_MAX6916
          This driver can also be built as a module. If so, the module
          will be called rtc-max6916.
 
+config RTC_DRV_PCA21125
+       tristate "NXP PCA21125"
+       help
+         If you say yes here you will get support for the
+         NXP PCA21125 SPI RTC chip.
+
+         This driver only supports the RTC feature, and not other chip
+         features such as alarms.
+
+         This driver can also be built as a module. If so, the module
+         will be called rtc-pca21125.
+
 config RTC_DRV_R9701
        tristate "Epson RTC-9701JE"
        help
diff --git a/drivers/rtc/Makefile b/drivers/rtc/Makefile
index 7cf7ad5..2c6af37 100644
--- a/drivers/rtc/Makefile
+++ b/drivers/rtc/Makefile
@@ -105,6 +105,7 @@ obj-$(CONFIG_RTC_DRV_NUC900)        += rtc-nuc900.o
 obj-$(CONFIG_RTC_DRV_OMAP)     += rtc-omap.o
 obj-$(CONFIG_RTC_DRV_OPAL)     += rtc-opal.o
 obj-$(CONFIG_RTC_DRV_PALMAS)   += rtc-palmas.o
+obj-$(CONFIG_RTC_DRV_PCA21125) += rtc-pca21125.o
 obj-$(CONFIG_RTC_DRV_PCAP)     += rtc-pcap.o
 obj-$(CONFIG_RTC_DRV_PCF2123)  += rtc-pcf2123.o
 obj-$(CONFIG_RTC_DRV_PCF2127)  += rtc-pcf2127.o
diff --git a/drivers/rtc/rtc-pca21125.c b/drivers/rtc/rtc-pca21125.c
index e69de29..8d42e4e 100644
--- a/drivers/rtc/rtc-pca21125.c
+++ b/drivers/rtc/rtc-pca21125.c
@@ -0,0 +1,164 @@
+       /* rtc-pca21125.c
+       *
+       * Driver for NXP  PCA21125 CMOS, SPI 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/init.h>
+       #include <linux/module.h>
+       #include <linux/device.h>
+       #include <linux/platform_device.h>
+       #include <linux/rtc.h>
+       #include <linux/spi/spi.h>
+       #include <linux/bcd.h>
+       
+       /* Registers in pca21125 rtc */
+       
+       #define PCA21125_SECONDS_REG    0x02
+       #define PCA21125_MINUTES_REG    0x03
+       #define PCA21125_HOURS_REG              0x04
+       #define PCA21125_DATE_REG               0x05
+       #define PCA21125_DAY_REG                0x06
+       #define PCA21125_MONTH_REG              0x07
+       #define PCA21125_YEAR_REG               0x08
+       #define PCA21125_CONTROL_REG    0x01
+       #define PCA21125_STATUS_REG     0x00
+       #define PCA21125_CLOCK_BURST    0x0D
+       
+       static int pca21125_read_reg(struct device *dev, unsigned char address,
+                                       unsigned char *data)
+       {
+               struct spi_device *spi = to_spi_device(dev);
+       
+               *data = address | 0x80;
+       
+               return spi_write_then_read(spi, data, 1, data, 1);
+       }
+       
+       static int pca21125_write_reg(struct device *dev, unsigned char address,
+                                       unsigned char data)
+       {
+               struct spi_device *spi = to_spi_device(dev);
+               unsigned char buf[2];
+       
+               buf[0] = address & 0x7F;
+               buf[1] = data;
+       
+               return spi_write_then_read(spi, buf, 2, NULL, 0);
+       }
+       
+       static int pca21125_read_time(struct device *dev, struct rtc_time *dt)
+       {
+               struct spi_device *spi = to_spi_device(dev);
+               int err;
+               unsigned char buf[8];
+       
+               buf[0] = PCA21125_CLOCK_BURST | 0x80;
+       
+               err = spi_write_then_read(spi, buf, 1, buf, 8);
+       
+               if (err)
+                       return err;
+       
+               dt->tm_sec = bcd2bin(buf[0]);
+               dt->tm_min = bcd2bin(buf[1]);
+               dt->tm_hour = bcd2bin(buf[2] & 0x3F);
+               dt->tm_mday = bcd2bin(buf[3]);
+               dt->tm_mon = bcd2bin(buf[4]) - 1;
+               dt->tm_wday = bcd2bin(buf[5]) - 1;
+               dt->tm_year = bcd2bin(buf[6]) + 100;
+       
+               return rtc_valid_tm(dt);
+       }
+       
+       static int pca21125_set_time(struct device *dev, struct rtc_time *dt)
+       {
+               struct spi_device *spi = to_spi_device(dev);
+               unsigned char buf[9];
+       
+               if (dt->tm_year < 100 || dt->tm_year > 199) {
+                       dev_err(&spi->dev, "Year must be between 2000 and 2099. 
It's %d.\n",
+                               dt->tm_year + 1900);
+               return -EINVAL;
+               }
+       
+               buf[0] = bin2bcd(dt->tm_sec);
+               buf[1] = bin2bcd(dt->tm_min);
+               buf[2] = (bin2bcd(dt->tm_hour) & 0X3F);
+               buf[3] = bin2bcd(dt->tm_mday);
+               buf[4] = bin2bcd(dt->tm_mon + 1);
+               buf[5] = bin2bcd(dt->tm_wday + 1);
+               buf[6] = bin2bcd(dt->tm_year % 100);
+               buf[7] = bin2bcd(0x00);
+       
+               /* write the rtc settings */
+               return spi_write_then_read(spi, buf, 9, NULL, 0);
+       }
+       
+       static const struct rtc_class_ops pca21125_rtc_ops = {
+               .read_time = pca21125_read_time,
+               .set_time = pca21125_set_time,
+       };
+       
+       static int pca21125_probe(struct spi_device *spi)
+       {
+               struct rtc_device *rtc;
+               unsigned char data;
+               int res;
+       
+               /* spi setup with pca21125 in mode 3 and bits per word as 8 */
+               spi->mode = SPI_MODE_3;
+               spi->bits_per_word = 8;
+               spi_setup(spi);
+       
+               /* RTC Settings */
+               res = pca21125_read_reg(&spi->dev, PCA21125_SECONDS_REG, &data);
+               if (res)
+                       return res;
+       
+               /* Disable the write protect of rtc */
+               pca21125_read_reg(&spi->dev, PCA21125_CONTROL_REG, &data);
+               data = data & ~(1 << 7);
+               pca21125_write_reg(&spi->dev, PCA21125_CONTROL_REG, data);
+       
+               /*Enable oscillator,disable oscillator stop flag, glitch 
filter*/
+               pca21125_read_reg(&spi->dev, PCA21125_STATUS_REG, &data);
+               data = data & 0x1B;
+               pca21125_write_reg(&spi->dev, PCA21125_STATUS_REG, data);
+       
+               /* display the settings */
+               pca21125_read_reg(&spi->dev, PCA21125_CONTROL_REG, &data);
+               dev_info(&spi->dev, "PCA21125 RTC CTRL Reg = 0x%02x\n", data);
+       
+               pca21125_read_reg(&spi->dev, PCA21125_STATUS_REG, &data);
+               dev_info(&spi->dev, "PCA21125 RTC Status Reg = 0x%02x\n", data);
+       
+               rtc = devm_rtc_device_register(&spi->dev, "pca21125",
+                                                       &pca21125_rtc_ops, 
THIS_MODULE);
+               if (IS_ERR(rtc))
+                       return PTR_ERR(rtc);
+       
+               spi_set_drvdata(spi, rtc);
+       
+               return 0;
+       }
+       
+       static struct spi_driver pca21125_driver = {
+               .driver = {
+                       .name = "pca21125",
+               },
+               .probe = pca21125_probe,
+       };
+       module_spi_driver(pca21125_driver);
+       
+       MODULE_DESCRIPTION("PCA21125 SPI RTC DRIVER");
+       MODULE_AUTHOR("Venkat Prashanth B U <venkat.prashanth2...@gmail.com>");
+       MODULE_LICENSE("GPL v2");
+       
-- 
1.9.2

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