[PATCH v6] Add Dallas DS1390/93/94 RTC chips

[PATCH v6] Add Dallas DS1390/93/94 RTC chips

[Mark Jackson]

v6 (!!) of this patch with even more code tidying as per previous comments.
Also only a single tx/rx buffer is used.
Now uses spi_write_then_read()
Comments changed to include extra chips in the family

This patch adds support for the Dallas DS1390/93/94 SPI RTC chip.

Signed-off-by: Mark Jackson <mpfj-kZtEnBLzDKq1Qrn1Bg8BZw@public.gmane.org>
---
 drivers/rtc/Kconfig      |   11 +++
 drivers/rtc/Makefile     |    1 +
 drivers/rtc/rtc-ds1390.c |  220 ++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 232 insertions(+), 0 deletions(-)

diff --git a/drivers/rtc/Kconfig b/drivers/rtc/Kconfig
index 814f49f..6e921e7 100644
--- a/drivers/rtc/Kconfig
+++ b/drivers/rtc/Kconfig
@@ -292,6 +292,17 @@ config RTC_DRV_DS1305
 	  This driver can also be built as a module. If so, the module
 	  will be called rtc-ds1305.
 
+config RTC_DRV_DS1390
+	tristate "Dallas/Maxim DS1390/93/94"
+	help
+	  If you say yes here you get support for the DS1390/93/94 chips.
+
+	  This driver only supports the RTC feature, and not other chip
+	  features such as alarms and trickle charging.
+
+	  This driver can also be built as a module. If so, the module
+	  will be called rtc-ds1390.
+
 config RTC_DRV_MAX6902
 	tristate "Maxim MAX6902"
 	help
diff --git a/drivers/rtc/Makefile b/drivers/rtc/Makefile
index d6a9ac7..316c3ce 100644
--- a/drivers/rtc/Makefile
+++ b/drivers/rtc/Makefile
@@ -28,6 +28,7 @@ obj-$(CONFIG_RTC_DRV_DS1302)	+= rtc-ds1302.o
 obj-$(CONFIG_RTC_DRV_DS1305)	+= rtc-ds1305.o
 obj-$(CONFIG_RTC_DRV_DS1307)	+= rtc-ds1307.o
 obj-$(CONFIG_RTC_DRV_DS1374)	+= rtc-ds1374.o
+obj-$(CONFIG_RTC_DRV_DS1390)	+= rtc-ds1390.o
 obj-$(CONFIG_RTC_DRV_DS1511)	+= rtc-ds1511.o
 obj-$(CONFIG_RTC_DRV_DS1553)	+= rtc-ds1553.o
 obj-$(CONFIG_RTC_DRV_DS1672)	+= rtc-ds1672.o
diff --git a/drivers/rtc/rtc-ds1390.c b/drivers/rtc/rtc-ds1390.c
new file mode 100644
index 0000000..16f70d4
--- /dev/null
+++ b/drivers/rtc/rtc-ds1390.c
@@ -0,0 +1,220 @@
+/*
+ * rtc-ds1390.c -- driver for DS1390/93/94
+ *
+ * Copyright (C) 2008 Mercury IMC Ltd
+ * Written by Mark Jackson <mpfj-kZtEnBLzDKq1Qrn1Bg8BZw@public.gmane.org>
+ *
+ * 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.
+ *
+ * NOTE : Currently this driver only supports the bare minimum for read
+ * and write the RTC.  The extra features provided by the chip family
+ * (alarms, trickle charger, different control registers) are unavailable.
+ */
+
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/platform_device.h>
+#include <linux/rtc.h>
+#include <linux/spi/spi.h>
+#include <linux/bcd.h>
+
+#define DS1390_REG_100THS		0x00
+#define DS1390_REG_SECONDS		0x01
+#define DS1390_REG_MINUTES		0x02
+#define DS1390_REG_HOURS		0x03
+#define DS1390_REG_DAY			0x04
+#define DS1390_REG_DATE			0x05
+#define DS1390_REG_MONTH_CENT		0x06
+#define DS1390_REG_YEAR			0x07
+
+#define DS1390_REG_ALARM_100THS		0x08
+#define DS1390_REG_ALARM_SECONDS	0x09
+#define DS1390_REG_ALARM_MINUTES	0x0A
+#define DS1390_REG_ALARM_HOURS		0x0B
+#define DS1390_REG_ALARM_DAY_DATE	0x0C
+
+#define DS1390_REG_CONTROL		0x0D
+#define DS1390_REG_STATUS		0x0E
+#define DS1390_REG_TRICKLE		0x0F
+
+struct ds1390 {
+	struct rtc_device *rtc;
+	u8 txrx_buf[9];	/* cmd + 8 registers */
+};
+
+static void ds1390_set_reg(struct device *dev, unsigned char address,
+				unsigned char data)
+{
+	struct spi_device *spi = to_spi_device(dev);
+	struct ds1390 *chip = dev_get_drvdata(dev);
+
+	/* Set MSB to indicate write */
+	chip->txrx_buf[0] = address | 0x80;
+	chip->txrx_buf[1] = data;
+
+	/* do the i/o */
+	spi_write_then_read(spi, chip->txrx_buf, 2, NULL, 0);
+}
+
+static int ds1390_get_reg(struct device *dev, unsigned char address,
+				unsigned char *data)
+{
+	struct spi_device *spi = to_spi_device(dev);
+	struct ds1390 *chip = dev_get_drvdata(dev);
+	int status;
+
+	/* Clear MSB to indicate read */
+	chip->txrx_buf[0] = address & 0x7f;
+	/* do the i/o */
+	status = spi_write_then_read(spi, chip->txrx_buf, 1, chip->txrx_buf, 1);
+	if (status != 0)
+		return status;
+
+	*data = chip->txrx_buf[1];
+
+	return 0;
+}
+
+static int ds1390_get_datetime(struct device *dev, struct rtc_time *dt)
+{
+	struct spi_device *spi = to_spi_device(dev);
+	struct ds1390 *chip = dev_get_drvdata(dev);
+	int status;
+
+	/* build the message */
+	chip->txrx_buf[0] = DS1390_REG_SECONDS;
+
+	/* do the i/o */
+	status = spi_write_then_read(spi, chip->txrx_buf, 1, chip->txrx_buf, 8);
+	if (status != 0)
+		return status;
+
+	/* The chip sends data in this order:
+	 * Seconds, Minutes, Hours, Day, Date, Month / Century, Year */
+	dt->tm_sec	= bcd2bin(chip->txrx_buf[0]);
+	dt->tm_min	= bcd2bin(chip->txrx_buf[1]);
+	dt->tm_hour	= bcd2bin(chip->txrx_buf[2]);
+	dt->tm_wday	= bcd2bin(chip->txrx_buf[3]);
+	dt->tm_mday	= bcd2bin(chip->txrx_buf[4]);
+	/* mask off century bit */
+	dt->tm_mon	= bcd2bin(chip->txrx_buf[5] & 0x7f) - 1;
+	/* adjust for century bit */
+	dt->tm_year	= bcd2bin(chip->txrx_buf[6]) +
+			  ((chip->txrx_buf[5] & 0x80) ? 100 : 0);
+
+	return rtc_valid_tm(dt);
+}
+
+static int ds1390_set_datetime(struct device *dev, struct rtc_time *dt)
+{
+	struct spi_device *spi = to_spi_device(dev);
+	struct ds1390 *chip = dev_get_drvdata(dev);
+
+	/* build the message */
+	chip->txrx_buf[0] = DS1390_REG_SECONDS | 0x80;
+	chip->txrx_buf[1] = bin2bcd(dt->tm_sec);
+	chip->txrx_buf[2] = bin2bcd(dt->tm_min);
+	chip->txrx_buf[3] = bin2bcd(dt->tm_hour);
+	chip->txrx_buf[4] = bin2bcd(dt->tm_wday);
+	chip->txrx_buf[5] = bin2bcd(dt->tm_mday);
+	chip->txrx_buf[6] = bin2bcd(dt->tm_mon + 1) |
+				((dt->tm_year > 99) ? 0x80 : 0x00);
+	chip->txrx_buf[7] = bin2bcd(dt->tm_year % 100);
+
+	/* do the i/o */
+	return spi_write_then_read(spi, chip->txrx_buf, 8, NULL, 0);
+}
+
+static int ds1390_read_time(struct device *dev, struct rtc_time *tm)
+{
+	return ds1390_get_datetime(dev, tm);
+}
+
+static int ds1390_set_time(struct device *dev, struct rtc_time *tm)
+{
+	return ds1390_set_datetime(dev, tm);
+}
+
+static const struct rtc_class_ops ds1390_rtc_ops = {
+	.read_time	= ds1390_read_time,
+	.set_time	= ds1390_set_time,
+};
+
+static int __devinit ds1390_probe(struct spi_device *spi)
+{
+	struct rtc_device *rtc;
+	unsigned char tmp;
+	struct ds1390 *chip;
+	int res;
+
+	printk(KERN_INFO "DS1390 SPI RTC driver\n");
+
+	chip = kzalloc(sizeof *chip, GFP_KERNEL);
+	if (!chip) {
+		printk(KERN_ALERT "DS1390: unable to allocate device memory\n");
+		return -ENOMEM;
+	}
+
+	spi->mode = SPI_MODE_3;
+	spi->bits_per_word = 8;
+	spi_setup(spi);
+
+	dev_set_drvdata(&spi->dev, chip);
+
+	res = ds1390_get_reg(&spi->dev, DS1390_REG_SECONDS, &tmp);
+	if (res) {
+		dev_err(&spi->dev, "DS1390: unable to read device\n");
+		kfree(chip);
+		return res;
+	}
+
+	rtc = rtc_device_register("ds1390",
+				&spi->dev, &ds1390_rtc_ops, THIS_MODULE);
+	if (IS_ERR(rtc)) {
+		dev_err(&spi->dev, "DS1390: unable to register device\n");
+		kfree(chip);
+		return PTR_ERR(rtc);
+	}
+	chip->rtc = rtc;
+
+	return 0;
+}
+
+static int __devexit ds1390_remove(struct spi_device *spi)
+{
+	struct ds1390 *chip = platform_get_drvdata(spi);
+	struct rtc_device *rtc = chip->rtc;
+
+	rtc_device_unregister(rtc);
+
+	kfree(chip);
+
+	return 0;
+}
+
+static struct spi_driver ds1390_driver = {
+	.driver = {
+		.name	= "rtc-ds1390",
+		.owner	= THIS_MODULE,
+	},
+	.probe	= ds1390_probe,
+	.remove = __devexit_p(ds1390_remove),
+};
+
+static __init int ds1390_init(void)
+{
+	return spi_register_driver(&ds1390_driver);
+}
+module_init(ds1390_init);
+
+static __exit void ds1390_exit(void)
+{
+	spi_unregister_driver(&ds1390_driver);
+}
+module_exit(ds1390_exit);
+
+MODULE_DESCRIPTION("DS1390/93/94 SPI RTC driver");
+MODULE_AUTHOR("Mark Jackson <mpfj-kZtEnBLzDKq1Qrn1Bg8BZw@public.gmane.org>");
+MODULE_LICENSE("GPL");

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Re: [rtc-linux] [PATCH v6] Add Dallas DS1390/93/94 RTC chips

[Alessandro Zummo]

On Thu, 06 Nov 2008 09:09:45 +0000
Mark Jackson <mpfj@mimc.co.uk> wrote:

> v6 (!!) of this patch with even more code tidying as per previous comments.

 I know.. I'm becoming stricter and stricter as the time goes by.. 

> Also only a single tx/rx buffer is used.
> Now uses spi_write_then_read()
> Comments changed to include extra chips in the family
> 
> This patch adds support for the Dallas DS1390/93/94 SPI RTC chip.

 There's still one printk left that you can avoid :)

-- 

 Best regards,

 Alessandro Zummo,
  Tower Technologies - Torino, Italy

  http://www.towertech.it

Re: [PATCH v6] Add Dallas DS1390/93/94 RTC chips

[David Brownell]

On Thursday 06 November 2008, Mark Jackson wrote:
> v6 (!!) of this patch with even more code tidying as per previous comments.
> Also only a single tx/rx buffer is used.
> Now uses spi_write_then_read()
> Comments changed to include extra chips in the family
> 
> This patch adds support for the Dallas DS1390/93/94 SPI RTC chip.
> 
> Signed-off-by: Mark Jackson <mpfj-kZtEnBLzDKq1Qrn1Bg8BZw@public.gmane.org>

Acked-by: David Brownell <dbrownell-Rn4VEauK+AKRv+LV9MX5uipxlwaOVQ5f@public.gmane.org>

Although I wouldn't bother using the "wday" field at all.
Linux doesn't use that field, so trying to maintain it isn't
useful ... though it probably doesn't hurt, assuming the
chip behaves OK when invalid data is written there.


Also, in probe():

> +       printk(KERN_INFO "DS1390 SPI RTC driver\n");

I dislike those banners in general.  Best to remove that,
since the RTC framework announces the registration.  Or
at least, dev_info().


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

Unlikely to fail ... but 

	res = spi_setup(spi);
	if (res < 0) {
		/* or do it before the kzalloc, no kfree
		 * ... likewise with reading the register
		 * as an "is it there" check:  do it earlier
		 * and get a similar minor codeshrink.
		 */
		kfree(chip);
		return res;
	}

> +
> +	dev_set_drvdata(&spi->dev, chip);
> +
> +	res = ds1390_get_reg(&spi->dev, DS1390_REG_SECONDS, &tmp);
> +	if (res) {
> +		dev_err(&spi->dev, "DS1390: unable to read device\n");
> +		kfree(chip);
> +		return res;
> +	}
> +
> +	rtc = rtc_device_register("ds1390",
> +				&spi->dev, &ds1390_rtc_ops, THIS_MODULE);

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