This patch adds support for the MAX6902 SPI RTC chip. Applies on 2.6.17-rc5. Tested on a
pxa2xx cpu.
Signed-off-by: Raphael Assenat <[email protected]>
---
--- linux-2.6.17-rc5/drivers/rtc/Kconfig 2006-05-24 21:50:17.000000000 -0400
+++ linux-2.6.17-rc5-8d/drivers/rtc/Kconfig 2006-05-25 15:59:53.000000000 -0400
@@ -172,4 +172,14 @@
This driver can also be built as a module. If so, the module
will be called rtc-test.
+config RTC_DRV_MAX6902
+ tristate "Maxim 6902"
+ depends on RTC_CLASS && SPI
+ help
+ If you say yes here you will get support for the
+ Maxim MAX6902 spi RTC chip.
+
+ This driver can also be built as a module. If so, the module
+ will be called rtc-max6902.
+
endmenu
--- linux-2.6.17-rc5/drivers/rtc/Makefile 2006-05-24 21:50:17.000000000 -0400
+++ linux-2.6.17-rc5-8d/drivers/rtc/Makefile 2006-05-25 15:58:38.000000000 -0400
@@ -20,3 +20,4 @@
obj-$(CONFIG_RTC_DRV_EP93XX) += rtc-ep93xx.o
obj-$(CONFIG_RTC_DRV_SA1100) += rtc-sa1100.o
obj-$(CONFIG_RTC_DRV_VR41XX) += rtc-vr41xx.o
+obj-$(CONFIG_RTC_DRV_MAX6902) += rtc-max6902.o
--- linux-2.6.17-rc5/drivers/rtc/rtc-max6902.c 1969-12-31 19:00:00.000000000 -0500
+++ linux-2.6.17-rc5-8d/drivers/rtc/rtc-max6902.c 2006-05-30 11:11:23.000000000 -0400
@@ -0,0 +1,289 @@
+/* drivers/char/max6902.c
+ *
+ * Copyright (C) 2006 8D Technologies inc.
+ * Copyright (C) 2004 Compulab Ltd.
+ *
+ * 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.
+ *
+ * Driver for MAX6902 spi RTC
+ *
+ * Changelog:
+ *
+ * 24-May-2006: Raphael Assenat <[email protected]>
+ * - Major rework
+ * Converted to rtc_device and uses the SPI layer.
+ *
+ * ??-???-2005: Someone at Compulab
+ * - Initial driver creation.
+ */
+
+#include <linux/config.h>
+#include <linux/module.h>
+#include <linux/version.h>
+
+#include <linux/kernel.h>
+#include <linux/platform_device.h>
+#include <linux/init.h>
+#include <linux/rtc.h>
+#include <linux/spi/spi.h>
+#include <linux/bcd.h>
+
+#include <asm/delay.h>
+
+#define MAX6902_REG_SECONDS 0x01
+#define MAX6902_REG_MINUTES 0x03
+#define MAX6902_REG_HOURS 0x05
+#define MAX6902_REG_DATE 0x07
+#define MAX6902_REG_MONTH 0x09
+#define MAX6902_REG_DAY 0x0B
+#define MAX6902_REG_YEAR 0x0D
+#define MAX6902_REG_CONTROL 0x0F
+#define MAX6902_REG_CENTURY 0x13
+
+
+//#define RTC_DEBUG
+
+struct max6902 {
+ struct rtc_device *rtc;
+ u8 buf[9]; /* Burst read cmd + 8 registers */
+ u8 tx_buf[2];
+ u8 rx_buf[2];
+};
+
+static void max6902_set_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;
+
+ spi_write(spi, buf, 2);
+}
+
+static int max6902_get_reg(struct device *dev, unsigned char address, unsigned char *data)
+{
+ struct spi_device *spi = to_spi_device(dev);
+ struct max6902 *chip = dev_get_drvdata(dev);
+ struct spi_message message;
+ struct spi_transfer xfer;
+ int status;
+
+ if (!data) return -EINVAL;
+
+ /* Build our spi message */
+ spi_message_init(&message);
+ memset(&xfer, 0, sizeof(xfer));
+ xfer.len = 2;
+ /* Can tx_buf and rx_buf be equal? The doc in spi.h is not sure... */
+ xfer.tx_buf = chip->tx_buf;
+ xfer.rx_buf = chip->rx_buf;
+
+ /* Set MSB to indicate read */
+ chip->tx_buf[0] = address | 0x80;
+
+ spi_message_add_tail(&xfer, &message);
+
+ /* do the i/o */
+ status = spi_sync(spi, &message);
+ if (status == 0) {
+ status = message.status;
+ }
+ else
+ return status;
+
+ *data = chip->rx_buf[1];
+
+ return status;
+}
+
+static int max6902_get_datetime(struct device *dev, struct rtc_time *dt)
+{
+ unsigned char tmp;
+ int century;
+ int err;
+
+ struct spi_device *spi = to_spi_device(dev);
+ struct max6902 *chip = dev_get_drvdata(dev);
+ struct spi_message message;
+ struct spi_transfer xfer;
+ int status;
+
+ err = max6902_get_reg(dev, MAX6902_REG_CENTURY, &tmp);
+ if (err)
+ return err;
+
+ /* build the message */
+ spi_message_init(&message);
+ memset(&xfer, 0, sizeof(xfer));
+ xfer.len = 1 + 7; /* Burst read command + 7 registers */
+ xfer.tx_buf = chip->buf;
+ xfer.rx_buf = chip->buf;
+ chip->buf[0] = 0xbf; // Burst read
+ spi_message_add_tail(&xfer, &message);
+
+ /* do the i/o */
+ status = spi_sync(spi, &message);
+ if (status == 0) {
+ status = message.status;
+ }
+ else
+ return status;
+
+ /* The chip sends data in this order:
+ * Seconds, Minutes, Hours, Date, Month, Day, Year */
+ dt->tm_sec = BCD2BIN(chip->buf[1]);
+ dt->tm_min = BCD2BIN(chip->buf[2]);
+ dt->tm_hour = BCD2BIN(chip->buf[3]);
+ dt->tm_mday = BCD2BIN(chip->buf[4]);
+ dt->tm_mon = BCD2BIN(chip->buf[5] - 1);
+ dt->tm_wday = BCD2BIN(chip->buf[6]);
+ dt->tm_year = BCD2BIN(chip->buf[7]);
+
+
+ century = BCD2BIN(tmp) * 100;
+
+ dt->tm_year += century;
+ dt->tm_year -= 1900;
+
+#ifdef RTC_DEBUG
+ printk("\n%s : Read RTC values\n",__FUNCTION__);
+ printk("tm_hour: %i\n",dt->tm_hour);
+ printk("tm_min : %i\n",dt->tm_min);
+ printk("tm_sec : %i\n",dt->tm_sec);
+ printk("tm_year: %i\n",dt->tm_year);
+ printk("tm_mon : %i\n",dt->tm_mon);
+ printk("tm_mday: %i\n",dt->tm_mday);
+ printk("tm_wday: %i\n",dt->tm_wday);
+#endif
+
+ return 0;
+}
+
+static int max6902_set_datetime(struct device *dev, struct rtc_time *dt)
+{
+ dt->tm_year = dt->tm_year+1900;
+
+#ifdef RTC_DEBUG
+ printk("\n%s : Setting RTC values\n",__FUNCTION__);
+ printk("tm_sec : %i\n",dt->tm_sec);
+ printk("tm_min : %i\n",dt->tm_min);
+ printk("tm_hour: %i\n",dt->tm_hour);
+ printk("tm_mday: %i\n",dt->tm_mday);
+ printk("tm_wday: %i\n",dt->tm_wday);
+ printk("tm_year: %i\n",dt->tm_year);
+#endif
+
+ // Remove write protection
+ max6902_set_reg(dev, 0xF, 0);
+
+ max6902_set_reg(dev, 0x01, BIN2BCD(dt->tm_sec));
+ max6902_set_reg(dev, 0x03, BIN2BCD(dt->tm_min));
+ max6902_set_reg(dev, 0x05, BIN2BCD(dt->tm_hour));
+
+ max6902_set_reg(dev, 0x07, BIN2BCD(dt->tm_mday));
+ max6902_set_reg(dev, 0x09, BIN2BCD(dt->tm_mon+1));
+ max6902_set_reg(dev, 0x0B, BIN2BCD(dt->tm_wday));
+ max6902_set_reg(dev, 0x0D, BIN2BCD(dt->tm_year%100));
+ max6902_set_reg(dev, 0x13, BIN2BCD(dt->tm_year/100));
+
+ /* Compulab used a delay here. However, the datasheet
+ * does not mention a delay being required anywhere... */
+ /* delay(2000); */
+
+ // Write protect
+ max6902_set_reg(dev, 0xF, 0x80);
+
+ return 0;
+}
+
+static int max6902_read_time(struct device *dev, struct rtc_time *tm)
+{
+ return max6902_get_datetime(dev, tm);
+}
+
+static int max6902_set_time(struct device *dev, struct rtc_time *tm)
+{
+ return max6902_set_datetime(dev, tm);
+}
+
+static struct rtc_class_ops max6902_rtc_ops = {
+ .read_time = max6902_read_time,
+ .set_time = max6902_set_time,
+};
+
+static int __devinit max6902_probe(struct spi_device *spi)
+{
+ struct rtc_device *rtc;
+ unsigned char tmp;
+ struct max6902 *chip;
+ int res;
+
+ rtc = rtc_device_register("max6902",
+ &spi->dev, &max6902_rtc_ops, THIS_MODULE);
+ if (IS_ERR(rtc)) {
+ return PTR_ERR(rtc);
+ }
+
+ spi->mode = SPI_MODE_3;
+ spi->bits_per_word = 8;
+ spi_setup(spi);
+
+ chip = kzalloc(sizeof *chip, GFP_KERNEL);
+ if (!chip) {
+ rtc_device_unregister(rtc);
+ return -ENOMEM;
+ }
+ chip->rtc = rtc;
+ dev_set_drvdata(&spi->dev, chip);
+
+ res = max6902_get_reg(&spi->dev, MAX6902_REG_SECONDS, &tmp);
+ if (res) {
+ rtc_device_unregister(rtc);
+ return res;
+ }
+
+ return 0;
+}
+
+static int __devexit max6902_remove(struct spi_device *spi)
+{
+ struct max6902 *chip = platform_get_drvdata(spi);
+ struct rtc_device *rtc = chip->rtc;
+
+ if (rtc)
+ rtc_device_unregister(rtc);
+
+ return 0;
+}
+
+static struct spi_driver max6902_driver = {
+ .driver = {
+ .name = "max6902",
+ .bus = &spi_bus_type,
+ .owner = THIS_MODULE,
+ },
+ .probe = max6902_probe,
+ .remove = __devexit_p(max6902_remove),
+};
+
+static __init int max6902_init(void)
+{
+ printk("max6902 spi driver\n");
+ return spi_register_driver(&max6902_driver);
+}
+module_init(max6902_init);
+
+static __exit void max6902_exit(void)
+{
+ spi_unregister_driver(&max6902_driver);
+}
+module_exit(max6902_exit);
+
+MODULE_DESCRIPTION ("max6902 spi RTC driver");
+MODULE_AUTHOR ("Raphael Assenat");
+MODULE_LICENSE ("GPL");
-
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