[PATCH] RTC: add rtc-rs5c348 driver

Add an SPI driver for the Ricoh RS5C348 RTC chip.

Signed-off-by: Atsushi Nemoto <anemo@mba.ocn.ne.jp>
Acked-by: Alessandro Zummo <a.zummo@towertech.it>
Cc: David Brownell <david-b@pacbell.net>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 246 insertions, 0 deletions

diff --git a/drivers/rtc/rtc-rs5c348.c b/drivers/rtc/rtc-rs5c348.c
new file mode 100644
index 0000000..0964d1d
--- /dev/null
+++ b/drivers/rtc/rtc-rs5c348.c
@@ -0,0 +1,246 @@
+/*
+ * A SPI driver for the Ricoh RS5C348 RTC
+ *
+ * Copyright (C) 2006 Atsushi Nemoto <anemo@mba.ocn.ne.jp>
+ *
+ * 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.
+ *
+ * The board specific init code should provide characteristics of this
+ * device:
+ *     Mode 1 (High-Active, Shift-Then-Sample), High Avtive CS
+ */
+
+#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/workqueue.h>
+#include <linux/spi/spi.h>
+
+#define DRV_VERSION "0.1"
+
+#define RS5C348_REG_SECS	0
+#define RS5C348_REG_MINS	1
+#define RS5C348_REG_HOURS	2
+#define RS5C348_REG_WDAY	3
+#define RS5C348_REG_DAY	4
+#define RS5C348_REG_MONTH	5
+#define RS5C348_REG_YEAR	6
+#define RS5C348_REG_CTL1	14
+#define RS5C348_REG_CTL2	15
+
+#define RS5C348_SECS_MASK	0x7f
+#define RS5C348_MINS_MASK	0x7f
+#define RS5C348_HOURS_MASK	0x3f
+#define RS5C348_WDAY_MASK	0x03
+#define RS5C348_DAY_MASK	0x3f
+#define RS5C348_MONTH_MASK	0x1f
+
+#define RS5C348_BIT_PM	0x20	/* REG_HOURS */
+#define RS5C348_BIT_Y2K	0x80	/* REG_MONTH */
+#define RS5C348_BIT_24H	0x20	/* REG_CTL1 */
+#define RS5C348_BIT_XSTP	0x10	/* REG_CTL2 */
+#define RS5C348_BIT_VDET	0x40	/* REG_CTL2 */
+
+#define RS5C348_CMD_W(addr)	(((addr) << 4) | 0x08)	/* single write */
+#define RS5C348_CMD_R(addr)	(((addr) << 4) | 0x0c)	/* single read */
+#define RS5C348_CMD_MW(addr)	(((addr) << 4) | 0x00)	/* burst write */
+#define RS5C348_CMD_MR(addr)	(((addr) << 4) | 0x04)	/* burst read */
+
+struct rs5c348_plat_data {
+	struct rtc_device *rtc;
+	int rtc_24h;
+};
+
+static int
+rs5c348_rtc_set_time(struct device *dev, struct rtc_time *tm)
+{
+	struct spi_device *spi = to_spi_device(dev);
+	struct rs5c348_plat_data *pdata = spi->dev.platform_data;
+	u8 txbuf[5+7], *txp;
+	int ret;
+
+	/* Transfer 5 bytes before writing SEC.  This gives 31us for carry. */
+	txp = txbuf;
+	txbuf[0] = RS5C348_CMD_R(RS5C348_REG_CTL2); /* cmd, ctl2 */
+	txbuf[1] = 0;	/* dummy */
+	txbuf[2] = RS5C348_CMD_R(RS5C348_REG_CTL2); /* cmd, ctl2 */
+	txbuf[3] = 0;	/* dummy */
+	txbuf[4] = RS5C348_CMD_MW(RS5C348_REG_SECS); /* cmd, sec, ... */
+	txp = &txbuf[5];
+	txp[RS5C348_REG_SECS] = BIN2BCD(tm->tm_sec);
+	txp[RS5C348_REG_MINS] = BIN2BCD(tm->tm_min);
+	if (pdata->rtc_24h) {
+		txp[RS5C348_REG_HOURS] = BIN2BCD(tm->tm_hour);
+	} else {
+		/* hour 0 is AM12, noon is PM12 */
+		txp[RS5C348_REG_HOURS] = BIN2BCD((tm->tm_hour + 11) % 12 + 1) |
+			(tm->tm_hour >= 12 ? RS5C348_BIT_PM : 0);
+	}
+	txp[RS5C348_REG_WDAY] = BIN2BCD(tm->tm_wday);
+	txp[RS5C348_REG_DAY] = BIN2BCD(tm->tm_mday);
+	txp[RS5C348_REG_MONTH] = BIN2BCD(tm->tm_mon + 1) |
+		(tm->tm_year >= 100 ? RS5C348_BIT_Y2K : 0);
+	txp[RS5C348_REG_YEAR] = BIN2BCD(tm->tm_year % 100);
+	/* write in one transfer to avoid data inconsistency */
+	ret = spi_write_then_read(spi, txbuf, sizeof(txbuf), NULL, 0);
+	udelay(62);	/* Tcsr 62us */
+	return ret;
+}
+
+static int
+rs5c348_rtc_read_time(struct device *dev, struct rtc_time *tm)
+{
+	struct spi_device *spi = to_spi_device(dev);
+	struct rs5c348_plat_data *pdata = spi->dev.platform_data;
+	u8 txbuf[5], rxbuf[7];
+	int ret;
+
+	/* Transfer 5 byte befores reading SEC.  This gives 31us for carry. */
+	txbuf[0] = RS5C348_CMD_R(RS5C348_REG_CTL2); /* cmd, ctl2 */
+	txbuf[1] = 0;	/* dummy */
+	txbuf[2] = RS5C348_CMD_R(RS5C348_REG_CTL2); /* cmd, ctl2 */
+	txbuf[3] = 0;	/* dummy */
+	txbuf[4] = RS5C348_CMD_MR(RS5C348_REG_SECS); /* cmd, sec, ... */
+
+	/* read in one transfer to avoid data inconsistency */
+	ret = spi_write_then_read(spi, txbuf, sizeof(txbuf),
+				  rxbuf, sizeof(rxbuf));
+	udelay(62);	/* Tcsr 62us */
+	if (ret < 0)
+		return ret;
+
+	tm->tm_sec = BCD2BIN(rxbuf[RS5C348_REG_SECS] & RS5C348_SECS_MASK);
+	tm->tm_min = BCD2BIN(rxbuf[RS5C348_REG_MINS] & RS5C348_MINS_MASK);
+	tm->tm_hour = BCD2BIN(rxbuf[RS5C348_REG_HOURS] & RS5C348_HOURS_MASK);
+	if (!pdata->rtc_24h) {
+		tm->tm_hour %= 12;
+		if (rxbuf[RS5C348_REG_HOURS] & RS5C348_BIT_PM)
+			tm->tm_hour += 12;
+	}
+	tm->tm_wday = BCD2BIN(rxbuf[RS5C348_REG_WDAY] & RS5C348_WDAY_MASK);
+	tm->tm_mday = BCD2BIN(rxbuf[RS5C348_REG_DAY] & RS5C348_DAY_MASK);
+	tm->tm_mon =
+		BCD2BIN(rxbuf[RS5C348_REG_MONTH] & RS5C348_MONTH_MASK) - 1;
+	/* year is 1900 + tm->tm_year */
+	tm->tm_year = BCD2BIN(rxbuf[RS5C348_REG_YEAR]) +
+		((rxbuf[RS5C348_REG_MONTH] & RS5C348_BIT_Y2K) ? 100 : 0);
+
+	if (rtc_valid_tm(tm) < 0) {
+		dev_err(&spi->dev, "retrieved date/time is not valid.\n");
+		rtc_time_to_tm(0, tm);
+	}
+
+	return 0;
+}
+
+static struct rtc_class_ops rs5c348_rtc_ops = {
+	.read_time	= rs5c348_rtc_read_time,
+	.set_time	= rs5c348_rtc_set_time,
+};
+
+static struct spi_driver rs5c348_driver;
+
+static int __devinit rs5c348_probe(struct spi_device *spi)
+{
+	int ret;
+	struct rtc_device *rtc;
+	struct rs5c348_plat_data *pdata;
+
+	pdata = kzalloc(sizeof(struct rs5c348_plat_data), GFP_KERNEL);
+	if (!pdata)
+		return -ENOMEM;
+	spi->dev.platform_data = pdata;
+
+	/* Check D7 of SECOND register */
+	ret = spi_w8r8(spi, RS5C348_CMD_R(RS5C348_REG_SECS));
+	if (ret < 0 || (ret & 0x80)) {
+		dev_err(&spi->dev, "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);
+
+	/* turn RTC on if it was not on */
+	ret = spi_w8r8(spi, RS5C348_CMD_R(RS5C348_REG_CTL2));
+	if (ret < 0)
+		goto kfree_exit;
+	if (ret & (RS5C348_BIT_XSTP | RS5C348_BIT_VDET)) {
+		u8 buf[2];
+		if (ret & RS5C348_BIT_VDET)
+			dev_warn(&spi->dev, "voltage-low detected.\n");
+		buf[0] = RS5C348_CMD_W(RS5C348_REG_CTL2);
+		buf[1] = 0;
+		ret = spi_write_then_read(spi, buf, sizeof(buf), NULL, 0);
+		if (ret < 0)
+			goto kfree_exit;
+	}
+
+	ret = spi_w8r8(spi, RS5C348_CMD_R(RS5C348_REG_CTL1));
+	if (ret < 0)
+		goto kfree_exit;
+	if (ret & RS5C348_BIT_24H)
+		pdata->rtc_24h = 1;
+
+	rtc = rtc_device_register(rs5c348_driver.driver.name, &spi->dev,
+				  &rs5c348_rtc_ops, THIS_MODULE);
+
+	if (IS_ERR(rtc)) {
+		ret = PTR_ERR(rtc);
+		goto kfree_exit;
+	}
+
+	pdata->rtc = rtc;
+
+	return 0;
+ kfree_exit:
+	kfree(pdata);
+	return ret;
+}
+
+static int __devexit rs5c348_remove(struct spi_device *spi)
+{
+	struct rs5c348_plat_data *pdata = spi->dev.platform_data;
+	struct rtc_device *rtc = pdata->rtc;
+
+	if (rtc)
+		rtc_device_unregister(rtc);
+	kfree(pdata);
+	return 0;
+}
+
+static struct spi_driver rs5c348_driver = {
+	.driver = {
+		.name	= "rs5c348",
+		.bus	= &spi_bus_type,
+		.owner	= THIS_MODULE,
+	},
+	.probe	= rs5c348_probe,
+	.remove	= __devexit_p(rs5c348_remove),
+};
+
+static __init int rs5c348_init(void)
+{
+	return spi_register_driver(&rs5c348_driver);
+}
+
+static __exit void rs5c348_exit(void)
+{
+	spi_unregister_driver(&rs5c348_driver);
+}
+
+module_init(rs5c348_init);
+module_exit(rs5c348_exit);
+
+MODULE_AUTHOR("Atsushi Nemoto <anemo@mba.ocn.ne.jp>");
+MODULE_DESCRIPTION("Ricoh RS5C348 RTC driver");
+MODULE_LICENSE("GPL");
+MODULE_VERSION(DRV_VERSION);