[PATCH] rtc: add support for rtc NXP pca21125

[VENKAT PRASHANTH B U]

This is the patch to add support for
NXP rtc pca21125

Signed-off-by: Venkat Prashanth B U <venkat.pra...@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.pra...@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.pra...@gmail.com>");
+ MODULE_LICENSE("GPL v2");
+
--
1.9.2

[Alexandre Belloni]

Hi,

Don't forget to Cc the rtc-linux mailing list.

Also, please please run checkpatch on your patches

The whole file is badly indented

Those are defined but not used

I'm not sure to understand how this can actually work, time/date starts
at 0x2

Isn't it necessary to write the address on the bus first? How does that
work?

Is that read useful?

> + /* Disable the write protect of rtc */
> + pca21125_read_reg(&spi->dev, PCA21125_CONTROL_REG, &data);
> + data = data & ~(1 << 7);

This is a magic value, please use a define

> + 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;

ditto

> + 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);
> +

I don't think anybody actually cares about that information

> + pca21125_read_reg(&spi->dev, PCA21125_STATUS_REG, &data);
> + dev_info(&spi->dev, "PCA21125 RTC Status Reg = 0x%02x\n", data);
> +

ditto

> + 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.pra...@gmail.com>");
> + MODULE_LICENSE("GPL v2");
> +
> --
> 1.9.2
>

--
Alexandre Belloni, Free Electrons
Embedded Linux and Kernel engineering
http://free-electrons.com

[VENKAT PRASHANTH B U]

This is a patch to add support for

NXP rtc pca21125

Signed-off-by: Venkat Prashanth B U <venkat.pra...@gmail.com>
---

changelog v2:
1. used the registers defined in pca21125_set_time function
2. code cleanup in the function pca21125_read_time function
3. Write the address on the bus with pca21125_write_reg function
4. code clean up on pca21125_probe function
5. Add the alarm feature support feature in the driver code
6. fixed the indentation of entire file
---
---
drivers/rtc/Kconfig | 9 ++
drivers/rtc/Makefile | 1 +
drivers/rtc/rtc-pca21125.c | 234 +++++++++++++++++++++++++++++++++++++++++++++
3 files changed, 244 insertions(+)

diff --git a/drivers/rtc/Kconfig b/drivers/rtc/Kconfig
index e215f50..29f40cb 100644
--- a/drivers/rtc/Kconfig
+++ b/drivers/rtc/Kconfig
@@ -739,6 +739,15 @@ config RTC_DRV_PCF2123

This driver can also be built as a module. If so, the module

will be called rtc-pcf2123.

+config RTC_DRV_PCA21125
+ tristate "NXP PCA21125"
+ help

+ If you say yes here you get support for the NXP PCA21125
+ RTC chip.
+

+ This driver can also be built as a module. If so, the module
+ will be called rtc-pca21125.
+

config RTC_DRV_MCP795
tristate "Microchip MCP795"

help
diff --git a/drivers/rtc/Makefile b/drivers/rtc/Makefile

index 7cf7ad5..41a5807 100644
--- a/drivers/rtc/Makefile
+++ b/drivers/rtc/Makefile
@@ -106,6 +106,7 @@ 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-$(CONFIG_RTC_DRV_PCAP) += rtc-pcap.o
+obj-$(CONFIG_RTC_DRV_PCA21125) += rtc-pca21125.o

obj-$(CONFIG_RTC_DRV_PCF2123) += rtc-pcf2123.o
obj-$(CONFIG_RTC_DRV_PCF2127) += rtc-pcf2127.o

obj-$(CONFIG_RTC_DRV_PCF50633) += rtc-pcf50633.o
diff --git a/drivers/rtc/rtc-pca21125.c b/drivers/rtc/rtc-pca21125.c
index e69de29..536cf50 100644
--- a/drivers/rtc/rtc-pca21125.c
+++ b/drivers/rtc/rtc-pca21125.c
@@ -0,0 +1,234 @@

+ /* rtc-pca21125.c
+ *
+ * Driver for NXP PCA21125 CMOS, SPI Compatible
+ * Real Time Clock
+ *
+ * Author : Venkat Prashanth B U <venkat.pra...@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>

+ #include <linux/interrupt.h>
+ #include <linux/regmap.h>
+ #include <linux/pm.h>
+ #include <linux/pm_wakeirq.h>
+ #include <linux/slab.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
+

+ struct pca21125_priv {
+
+ struct spi_device *spi;
+ struct rtc_device *rtc;
+ struct regmap *map;
+ struct mutex mutex;
+ unsigned int irqen;
+ int irq;
+ int alarm_sec;
+ int alarm_min;
+ int alarm_hour;
+ int alarm_mday;

+ };
+
+ static int

+ pca21125_read_alarm(struct device *dev, struct rtc_wkalrm *alarm)
+ {
+ struct pca21125_priv *priv = dev_get_drvdata(dev);
+ int res = 0;
+ unsigned int stat;
+
+ if (priv->irq <= 0)
+ return -EINVAL;
+
+ mutex_lock(&priv->mutex);
+
+ res = regmap_read(priv->map, PCA21125_STATUS_REG, &stat);
+ if (res)
+ goto out;
+
+ alarm->enabled = !!(priv->irqen & RTC_AF);
+
+ alarm->time.tm_sec = priv->alarm_sec < 0 ? 0 : priv->alarm_sec;
+ alarm->time.tm_min = priv->alarm_min < 0 ? 0 : priv->alarm_min;
+ alarm->time.tm_hour = priv->alarm_hour < 0 ? 0 : priv->alarm_hour;
+ alarm->time.tm_mday = priv->alarm_mday < 0 ? 0 : priv->alarm_mday;
+
+out:
+ mutex_unlock(&priv->mutex);
+ return res;

+ }
+
+ static int

+ pca21125_set_alarm(struct device *dev, struct rtc_wkalrm *alarm)
+ {
+ struct pca21125_priv *priv = dev_get_drvdata(dev);
+ int res = 0;
+
+ if (priv->irq <= 0)
+ return -EINVAL;
+
+ mutex_lock(&priv->mutex);
+
+ priv->alarm_sec = alarm->time.tm_sec;
+ priv->alarm_min = alarm->time.tm_min;
+ priv->alarm_hour = alarm->time.tm_hour;
+ priv->alarm_mday = alarm->time.tm_mday;
+
+ if (alarm->enabled)
+ priv->irqen |= RTC_AF;
+
+ mutex_unlock(&priv->mutex);
+
+ return res;

+ }
+
+ static int

+ pca21125_read_reg(struct device *dev, unsigned char address,

+ unsigned char *data)
+ {
+ struct spi_device *spi = to_spi_device(dev);

+ unsigned char buf[2];
+

+ /* Set MSB to indicate read */

+ *data = address | 0x80;
+

+ return spi_write_then_read(spi, buf, 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];
+

+ /* MSB must be '0' to write */

+ 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] = 0xbf; /* Burst read */

+
+ err = spi_write_then_read(spi, buf, 1, buf, 8);
+
+ if (err)
+ return err;
+

+ /* The chip sends data in the order mentioned below*/
+

+ dt->tm_sec = bcd2bin(buf[0]);
+ dt->tm_min = bcd2bin(buf[1]);

+ dt->tm_hour = bcd2bin(buf[2]);

+ dt->tm_mday = bcd2bin(buf[3]);

+ dt->tm_mon = bcd2bin(buf[4]);
+ dt->tm_wday = bcd2bin(buf[5]);

+ dt->tm_year = bcd2bin(buf[6]);
+

+ 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];
+

+ dt->tm_year = dt->tm_year + 1900;

+
+ 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;
+ }
+

+ /* Remove write protection */
+ pca21125_write_reg(dev, PCA21125_CONTROL_REG, 0);
+
+ pca21125_write_reg(dev, PCA21125_SECONDS_REG, bin2bcd(dt->tm_sec));
+ pca21125_write_reg(dev, PCA21125_MINUTES_REG, bin2bcd(dt->tm_min));
+ pca21125_write_reg(dev, PCA21125_HOURS_REG, bin2bcd(dt->tm_hour));
+ pca21125_write_reg(dev, PCA21125_DATE_REG, bin2bcd(dt->tm_mday));
+ pca21125_write_reg(dev, PCA21125_MONTH_REG, bin2bcd(dt->tm_mon + 1));
+ pca21125_write_reg(dev, PCA21125_DAY_REG, bin2bcd(dt->tm_wday));
+ pca21125_write_reg(dev, PCA21125_YEAR_REG, bin2bcd(dt->tm_year % 100));
+
+ /* Write protect */
+ pca21125_write_reg(dev, PCA21125_CONTROL_REG, 0x80);
+

+ /* 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,

+ .read_alarm = pca21125_read_alarm,
+ .set_alarm = pca21125_set_alarm,

+ };
+
+ static int

+ pca21125_probe(struct spi_device *spi)

+ {
+ struct rtc_device *rtc;

+ unsigned char tmp;
+ int res;
+

+ spi->mode = SPI_MODE_3;
+ spi->bits_per_word = 8;
+ spi_setup(spi);
+

+ res = pca21125_read_reg(&spi->dev, PCA21125_SECONDS_REG, &tmp);
+ if (res != 0)
+ return res;
+

+ 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.pra...@gmail.com>");
+ MODULE_LICENSE("GPL v2");

--
1.9.2

[Joachim Eastwood]

Hi Venkat,

On 19 October 2016 at 19:41, VENKAT PRASHANTH B U

<venkat.pra...@gmail.com> wrote:
> This is a patch to add support for
> NXP rtc pca21125

The register layout PCA21125 looks similar to PCF8563 which already
has a driver.

Would it be possible to support the PCA21125 device with the rtc-pcf8563 driver?
You will need to add a regmap layer since the PCA21125 is SPI while
the PCF8563 is I2C.


regards,
Joachim Eastwood