rtc: Philips PCF2123 RTC SPI driver

Add support for the Philips/NXP PCF2123 RTC.

Signed-off: Chris Verges <chrisv@cyberswitching.com>
Tested-by: Chris Verges <chrisv@cyberswitching.com>
Signed-off: Christian Pellegrin <chripell@fsfe.org>
Tested-by: Christian Pellegrin <chripell@fsfe.org>
Cc: Alessandro Zummo <a.zummo@towertech.it>
Cc: David Brownell <david-b@pacbell.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 344 insertions, 0 deletions

diff --git a/drivers/rtc/rtc-pcf2123.c b/drivers/rtc/rtc-pcf2123.c
new file mode 100644
index 00000000000..d07b199a0c9
--- /dev/null
+++ b/drivers/rtc/rtc-pcf2123.c
@@ -0,0 +1,344 @@
+/*
+ * An SPI driver for the Philips PCF2123 RTC
+ * Copyright 2009 Cyber Switching, Inc.
+ *
+ * Author: Chris Verges <chrisv@cyberswitching.com>
+ * Maintainers: http://www.cyberswitching.com
+ *
+ * based on the RS5C348 driver in this same directory.
+ *
+ * Thanks to Christian Pellegrin <chripell@fsfe.org> for
+ * the sysfs contributions to this driver.
+ *
+ * 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.
+ *
+ * Please note that the CS is active high, so platform data
+ * should look something like:
+ *
+ * static struct spi_board_info ek_spi_devices[] = {
+ * 	...
+ * 	{
+ * 		.modalias		= "rtc-pcf2123",
+ * 		.chip_select		= 1,
+ * 		.controller_data	= (void *)AT91_PIN_PA10,
+ *		.max_speed_hz		= 1000 * 1000,
+ *		.mode			= SPI_CS_HIGH,
+ *		.bus_num		= 0,
+ *	},
+ *	...
+ *};
+ *
+ */
+
+#include <linux/bcd.h>
+#include <linux/delay.h>
+#include <linux/device.h>
+#include <linux/errno.h>
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/string.h>
+#include <linux/rtc.h>
+#include <linux/spi/spi.h>
+
+#define DRV_VERSION "0.5"
+
+#define PCF2123_REG_CTRL1	(0x00)	/* Control Register 1 */
+#define PCF2123_REG_CTRL2	(0x01)	/* Control Register 2 */
+#define PCF2123_REG_SC		(0x02)	/* datetime */
+#define PCF2123_REG_MN		(0x03)
+#define PCF2123_REG_HR		(0x04)
+#define PCF2123_REG_DM		(0x05)
+#define PCF2123_REG_DW		(0x06)
+#define PCF2123_REG_MO		(0x07)
+#define PCF2123_REG_YR		(0x08)
+
+#define PCF2123_SUBADDR		(1 << 4)
+#define PCF2123_WRITE		((0 << 7) | PCF2123_SUBADDR)
+#define PCF2123_READ		((1 << 7) | PCF2123_SUBADDR)
+
+static struct spi_driver pcf2123_driver;
+
+struct pcf2123_sysfs_reg {
+	struct device_attribute attr; /* must be first */
+	char name[2];
+};
+
+struct pcf2123_plat_data {
+	struct rtc_device *rtc;
+	struct pcf2123_sysfs_reg regs[16];
+};
+
+/*
+ * Causes a 30 nanosecond delay to ensure that the PCF2123 chip select
+ * is released properly after an SPI write.  This function should be
+ * called after EVERY read/write call over SPI.
+ */
+static inline void pcf2123_delay_trec(void)
+{
+	ndelay(30);
+}
+
+static ssize_t pcf2123_show(struct device *dev, struct device_attribute *attr,
+			    char *buffer)
+{
+	struct spi_device *spi = to_spi_device(dev);
+	struct pcf2123_sysfs_reg *r = (struct pcf2123_sysfs_reg *) attr;
+	u8 txbuf[1], rxbuf[1];
+	int ret;
+
+	txbuf[0] = PCF2123_READ | simple_strtoul(r->name, NULL, 16);
+	ret = spi_write_then_read(spi, txbuf, 1, rxbuf, 1);
+	if (ret < 0)
+		return sprintf(buffer, "error: %d", ret);
+	pcf2123_delay_trec();
+	return sprintf(buffer, "0x%x", rxbuf[0]);
+}
+
+static ssize_t pcf2123_store(struct device *dev, struct device_attribute *attr,
+			     const char *buffer, size_t count) {
+	struct spi_device *spi = to_spi_device(dev);
+	struct pcf2123_sysfs_reg *r = (struct pcf2123_sysfs_reg *) attr;
+	u8 txbuf[2];
+	int ret;
+
+	txbuf[0] = PCF2123_WRITE | simple_strtoul(r->name, NULL, 16);
+	txbuf[1] = simple_strtoul(buffer, NULL, 0);
+	ret = spi_write(spi, txbuf, sizeof(txbuf));
+	if (ret < 0)
+		return -EIO;
+	pcf2123_delay_trec();
+	return count;
+}
+
+static int pcf2123_rtc_read_time(struct device *dev, struct rtc_time *tm)
+{
+	struct spi_device *spi = to_spi_device(dev);
+	u8 txbuf[1], rxbuf[7];
+	int ret;
+
+	txbuf[0] = PCF2123_READ | PCF2123_REG_SC;
+	ret = spi_write_then_read(spi, txbuf, sizeof(txbuf),
+			rxbuf, sizeof(rxbuf));
+	if (ret < 0)
+		return ret;
+	pcf2123_delay_trec();
+
+	tm->tm_sec = bcd2bin(rxbuf[0] & 0x7F);
+	tm->tm_min = bcd2bin(rxbuf[1] & 0x7F);
+	tm->tm_hour = bcd2bin(rxbuf[2] & 0x3F); /* rtc hr 0-23 */
+	tm->tm_mday = bcd2bin(rxbuf[3] & 0x3F);
+	tm->tm_wday = rxbuf[4] & 0x07;
+	tm->tm_mon = bcd2bin(rxbuf[5] & 0x1F) - 1; /* rtc mn 1-12 */
+	tm->tm_year = bcd2bin(rxbuf[6]);
+	if (tm->tm_year < 70)
+		tm->tm_year += 100;	/* assume we are in 1970...2069 */
+
+	dev_dbg(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);
+
+	/* the clock can give out invalid datetime, but we cannot return
+	 * -EINVAL otherwise hwclock will refuse to set the time on bootup.
+	 */
+	if (rtc_valid_tm(tm) < 0)
+		dev_err(dev, "retrieved date/time is not valid.\n");
+
+	return 0;
+}
+
+static int pcf2123_rtc_set_time(struct device *dev, struct rtc_time *tm)
+{
+	struct spi_device *spi = to_spi_device(dev);
+	u8 txbuf[8];
+	int ret;
+
+	dev_dbg(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);
+
+	/* Stop the counter first */
+	txbuf[0] = PCF2123_WRITE | PCF2123_REG_CTRL1;
+	txbuf[1] = 0x20;
+	ret = spi_write(spi, txbuf, 2);
+	if (ret < 0)
+		return ret;
+	pcf2123_delay_trec();
+
+	/* Set the new time */
+	txbuf[0] = PCF2123_WRITE | PCF2123_REG_SC;
+	txbuf[1] = bin2bcd(tm->tm_sec & 0x7F);
+	txbuf[2] = bin2bcd(tm->tm_min & 0x7F);
+	txbuf[3] = bin2bcd(tm->tm_hour & 0x3F);
+	txbuf[4] = bin2bcd(tm->tm_mday & 0x3F);
+	txbuf[5] = tm->tm_wday & 0x07;
+	txbuf[6] = bin2bcd((tm->tm_mon + 1) & 0x1F); /* rtc mn 1-12 */
+	txbuf[7] = bin2bcd(tm->tm_year < 100 ? tm->tm_year : tm->tm_year - 100);
+
+	ret = spi_write(spi, txbuf, sizeof(txbuf));
+	if (ret < 0)
+		return ret;
+	pcf2123_delay_trec();
+
+	/* Start the counter */
+	txbuf[0] = PCF2123_WRITE | PCF2123_REG_CTRL1;
+	txbuf[1] = 0x00;
+	ret = spi_write(spi, txbuf, 2);
+	if (ret < 0)
+		return ret;
+	pcf2123_delay_trec();
+
+	return 0;
+}
+
+static const struct rtc_class_ops pcf2123_rtc_ops = {
+	.read_time	= pcf2123_rtc_read_time,
+	.set_time	= pcf2123_rtc_set_time,
+};
+
+static int __devinit pcf2123_probe(struct spi_device *spi)
+{
+	struct rtc_device *rtc;
+	struct pcf2123_plat_data *pdata;
+	u8 txbuf[2], rxbuf[2];
+	int ret, i;
+
+	pdata = kzalloc(sizeof(struct pcf2123_plat_data), GFP_KERNEL);
+	if (!pdata)
+		return -ENOMEM;
+	spi->dev.platform_data = pdata;
+
+	/* Send a software reset command */
+	txbuf[0] = PCF2123_WRITE | PCF2123_REG_CTRL1;
+	txbuf[1] = 0x58;
+	dev_dbg(&spi->dev, "resetting RTC (0x%02X 0x%02X)\n",
+			txbuf[0], txbuf[1]);
+	ret = spi_write(spi, txbuf, 2 * sizeof(u8));
+	if (ret < 0)
+		return ret;
+	pcf2123_delay_trec();
+
+	/* Stop the counter */
+	txbuf[0] = PCF2123_WRITE | PCF2123_REG_CTRL1;
+	txbuf[1] = 0x20;
+	dev_dbg(&spi->dev, "stopping RTC (0x%02X 0x%02X)\n",
+			txbuf[0], txbuf[1]);
+	ret = spi_write(spi, txbuf, 2 * sizeof(u8));
+	if (ret < 0)
+		return ret;
+	pcf2123_delay_trec();
+
+	/* See if the counter was actually stopped */
+	txbuf[0] = PCF2123_READ | PCF2123_REG_CTRL1;
+	dev_dbg(&spi->dev, "checking for presence of RTC (0x%02X)\n",
+			txbuf[0]);
+	ret = spi_write_then_read(spi, txbuf, 1 * sizeof(u8),
+					rxbuf, 2 * sizeof(u8));
+	dev_dbg(&spi->dev, "received data from RTC (0x%02X 0x%02X)\n",
+			rxbuf[0], rxbuf[1]);
+	if (ret < 0)
+		goto kfree_exit;
+	pcf2123_delay_trec();
+
+	if (!(rxbuf[0] & 0x20)) {
+		dev_err(&spi->dev, "chip not found\n");
+		goto kfree_exit;
+	}
+
+	dev_info(&spi->dev, "chip found, driver version " DRV_VERSION "\n");
+	dev_info(&spi->dev, "spiclk %u KHz.\n",
+			(spi->max_speed_hz + 500) / 1000);
+
+	/* Start the counter */
+	txbuf[0] = PCF2123_WRITE | PCF2123_REG_CTRL1;
+	txbuf[1] = 0x00;
+	ret = spi_write(spi, txbuf, sizeof(txbuf));
+	if (ret < 0)
+		goto kfree_exit;
+	pcf2123_delay_trec();
+
+	/* Finalize the initialization */
+	rtc = rtc_device_register(pcf2123_driver.driver.name, &spi->dev,
+			&pcf2123_rtc_ops, THIS_MODULE);
+
+	if (IS_ERR(rtc)) {
+		dev_err(&spi->dev, "failed to register.\n");
+		ret = PTR_ERR(rtc);
+		goto kfree_exit;
+	}
+
+	pdata->rtc = rtc;
+
+	for (i = 0; i < 16; i++) {
+		sprintf(pdata->regs[i].name, "%1x", i);
+		pdata->regs[i].attr.attr.mode = S_IRUGO | S_IWUSR;
+		pdata->regs[i].attr.attr.name = pdata->regs[i].name;
+		pdata->regs[i].attr.show = pcf2123_show;
+		pdata->regs[i].attr.store = pcf2123_store;
+		ret = device_create_file(&spi->dev, &pdata->regs[i].attr);
+		if (ret) {
+			dev_err(&spi->dev, "Unable to create sysfs %s\n",
+				pdata->regs[i].name);
+			pdata->regs[i].name[0] = '\0';
+		}
+	}
+
+	return 0;
+kfree_exit:
+	kfree(pdata);
+	spi->dev.platform_data = NULL;
+	return ret;
+}
+
+static int pcf2123_remove(struct spi_device *spi)
+{
+	struct pcf2123_plat_data *pdata = spi->dev.platform_data;
+	int i;
+
+	if (pdata) {
+		struct rtc_device *rtc = pdata->rtc;
+
+		if (rtc)
+			rtc_device_unregister(rtc);
+		for (i = 0; i < 16; i++)
+			if (pdata->regs[i].name[0])
+				device_remove_file(&spi->dev,
+						   &pdata->regs[i].attr);
+		kfree(pdata);
+	}
+
+	return 0;
+}
+
+static struct spi_driver pcf2123_driver = {
+	.driver	= {
+			.name	= "rtc-pcf2123",
+			.bus	= &spi_bus_type,
+			.owner	= THIS_MODULE,
+	},
+	.probe	= pcf2123_probe,
+	.remove	= __devexit_p(pcf2123_remove),
+};
+
+static int __init pcf2123_init(void)
+{
+	return spi_register_driver(&pcf2123_driver);
+}
+
+static void __exit pcf2123_exit(void)
+{
+	spi_unregister_driver(&pcf2123_driver);
+}
+
+MODULE_AUTHOR("Chris Verges <chrisv@cyberswitching.com>");
+MODULE_DESCRIPTION("NXP PCF2123 RTC driver");
+MODULE_LICENSE("GPL");
+MODULE_VERSION(DRV_VERSION);
+
+module_init(pcf2123_init);
+module_exit(pcf2123_exit);