rtc: add Dallas DS2404 driver

[akpm@linux-foundation.org: fix warning]
Signed-off-by: Sven Schnelle <svens@stackframe.org>
Cc: Alessandro Zummo <a.zummo@towertech.it>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

drivers/rtc/Kconfig

@@ -660,6 +660,15 @@ config RTC_DRV_V3020
 	  This driver can also be built as a module. If so, the module
 	  will be called rtc-v3020.
 
+config RTC_DRV_DS2404
+	tristate "Dallas DS2404"
+	help
+	  If you say yes here you get support for the
+	  Dallas DS2404 RTC chip.
+
+	  This driver can also be built as a module. If so, the module
+	  will be called rtc-ds2404.
+
 config RTC_DRV_WM831X
 	tristate "Wolfson Microelectronics WM831x RTC"
 	depends on MFD_WM831X

drivers/rtc/Makefile

@@ -43,6 +43,7 @@ obj-$(CONFIG_RTC_DRV_DS1511)	+= rtc-ds1511.o
 obj-$(CONFIG_RTC_DRV_DS1553)	+= rtc-ds1553.o
 obj-$(CONFIG_RTC_DRV_DS1672)	+= rtc-ds1672.o
 obj-$(CONFIG_RTC_DRV_DS1742)	+= rtc-ds1742.o
+obj-$(CONFIG_RTC_DRV_DS2404)    += rtc-ds2404.o
 obj-$(CONFIG_RTC_DRV_DS3232)	+= rtc-ds3232.o
 obj-$(CONFIG_RTC_DRV_DS3234)	+= rtc-ds3234.o
 obj-$(CONFIG_RTC_DRV_EFI)	+= rtc-efi.o

drivers/rtc/rtc-ds2404.c

@@ -0,0 +1,303 @@
+/*
+ * Copyright (C) 2012 Sven Schnelle <svens@stackframe.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.
+ *
+ */
+
+#include <linux/platform_device.h>
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/rtc.h>
+#include <linux/types.h>
+#include <linux/bcd.h>
+#include <linux/rtc-ds2404.h>
+#include <linux/delay.h>
+#include <linux/gpio.h>
+#include <linux/slab.h>
+
+#include <linux/io.h>
+
+#define DS2404_STATUS_REG 0x200
+#define DS2404_CONTROL_REG 0x201
+#define DS2404_RTC_REG 0x202
+
+#define DS2404_WRITE_SCRATCHPAD_CMD 0x0f
+#define DS2404_READ_SCRATCHPAD_CMD 0xaa
+#define DS2404_COPY_SCRATCHPAD_CMD 0x55
+#define DS2404_READ_MEMORY_CMD 0xf0
+
+struct ds2404;
+
+struct ds2404_chip_ops {
+	int (*map_io)(struct ds2404 *chip, struct platform_device *pdev,
+		      struct ds2404_platform_data *pdata);
+	void (*unmap_io)(struct ds2404 *chip);
+};
+
+#define DS2404_RST	0
+#define DS2404_CLK	1
+#define DS2404_DQ	2
+
+struct ds2404_gpio {
+	const char *name;
+	unsigned int gpio;
+};
+
+struct ds2404 {
+	struct ds2404_gpio *gpio;
+	struct ds2404_chip_ops *ops;
+	struct rtc_device *rtc;
+};
+
+static struct ds2404_gpio ds2404_gpio[] = {
+	{ "RTC RST", 0 },
+	{ "RTC CLK", 0 },
+	{ "RTC DQ", 0 },
+};
+
+static int ds2404_gpio_map(struct ds2404 *chip, struct platform_device *pdev,
+			  struct ds2404_platform_data *pdata)
+{
+	int i, err;
+
+	ds2404_gpio[DS2404_RST].gpio = pdata->gpio_rst;
+	ds2404_gpio[DS2404_CLK].gpio = pdata->gpio_clk;
+	ds2404_gpio[DS2404_DQ].gpio = pdata->gpio_dq;
+
+	for (i = 0; i < ARRAY_SIZE(ds2404_gpio); i++) {
+		err = gpio_request(ds2404_gpio[i].gpio, ds2404_gpio[i].name);
+		if (err) {
+			printk(KERN_ERR "error mapping gpio %s: %d\n",
+				ds2404_gpio[i].name, err);
+			goto err_request;
+		}
+		if (i != DS2404_DQ)
+			gpio_direction_output(ds2404_gpio[i].gpio, 1);
+	}
+
+	chip->gpio = ds2404_gpio;
+	return 0;
+
+err_request:
+	while (--i >= 0)
+		gpio_free(ds2404_gpio[i].gpio);
+	return err;
+}
+
+static void ds2404_gpio_unmap(struct ds2404 *chip)
+{
+	int i;
+
+	for (i = 0; i < ARRAY_SIZE(ds2404_gpio); i++)
+		gpio_free(ds2404_gpio[i].gpio);
+}
+
+static struct ds2404_chip_ops ds2404_gpio_ops = {
+	.map_io		= ds2404_gpio_map,
+	.unmap_io	= ds2404_gpio_unmap,
+};
+
+static void ds2404_reset(struct device *dev)
+{
+	gpio_set_value(ds2404_gpio[DS2404_RST].gpio, 0);
+	udelay(1000);
+	gpio_set_value(ds2404_gpio[DS2404_RST].gpio, 1);
+	gpio_set_value(ds2404_gpio[DS2404_CLK].gpio, 0);
+	gpio_direction_output(ds2404_gpio[DS2404_DQ].gpio, 0);
+	udelay(10);
+}
+
+static void ds2404_write_byte(struct device *dev, u8 byte)
+{
+	int i;
+
+	gpio_direction_output(ds2404_gpio[DS2404_DQ].gpio, 1);
+	for (i = 0; i < 8; i++) {
+		gpio_set_value(ds2404_gpio[DS2404_DQ].gpio, byte & (1 << i));
+		udelay(10);
+		gpio_set_value(ds2404_gpio[DS2404_CLK].gpio, 1);
+		udelay(10);
+		gpio_set_value(ds2404_gpio[DS2404_CLK].gpio, 0);
+		udelay(10);
+	}
+}
+
+static u8 ds2404_read_byte(struct device *dev)
+{
+	int i;
+	u8 ret = 0;
+
+	gpio_direction_input(ds2404_gpio[DS2404_DQ].gpio);
+
+	for (i = 0; i < 8; i++) {
+		gpio_set_value(ds2404_gpio[DS2404_CLK].gpio, 0);
+		udelay(10);
+		if (gpio_get_value(ds2404_gpio[DS2404_DQ].gpio))
+			ret |= 1 << i;
+		gpio_set_value(ds2404_gpio[DS2404_CLK].gpio, 1);
+		udelay(10);
+	}
+	return ret;
+}
+
+static void ds2404_read_memory(struct device *dev, u16 offset,
+			       int length, u8 *out)
+{
+	ds2404_reset(dev);
+	ds2404_write_byte(dev, DS2404_READ_MEMORY_CMD);
+	ds2404_write_byte(dev, offset & 0xff);
+	ds2404_write_byte(dev, (offset >> 8) & 0xff);
+	while (length--)
+		*out++ = ds2404_read_byte(dev);
+}
+
+static void ds2404_write_memory(struct device *dev, u16 offset,
+				int length, u8 *out)
+{
+	int i;
+	u8 ta01, ta02, es;
+
+	ds2404_reset(dev);
+	ds2404_write_byte(dev, DS2404_WRITE_SCRATCHPAD_CMD);
+	ds2404_write_byte(dev, offset & 0xff);
+	ds2404_write_byte(dev, (offset >> 8) & 0xff);
+
+	for (i = 0; i < length; i++)
+		ds2404_write_byte(dev, out[i]);
+
+	ds2404_reset(dev);
+	ds2404_write_byte(dev, DS2404_READ_SCRATCHPAD_CMD);
+
+	ta01 = ds2404_read_byte(dev);
+	ta02 = ds2404_read_byte(dev);
+	es = ds2404_read_byte(dev);
+
+	for (i = 0; i < length; i++) {
+		if (out[i] != ds2404_read_byte(dev)) {
+			printk(KERN_ERR "read invalid data\n");
+			return;
+		}
+	}
+
+	ds2404_reset(dev);
+	ds2404_write_byte(dev, DS2404_COPY_SCRATCHPAD_CMD);
+	ds2404_write_byte(dev, ta01);
+	ds2404_write_byte(dev, ta02);
+	ds2404_write_byte(dev, es);
+
+	gpio_direction_input(ds2404_gpio[DS2404_DQ].gpio);
+	while (gpio_get_value(ds2404_gpio[DS2404_DQ].gpio))
+		;
+}
+
+static void ds2404_enable_osc(struct device *dev)
+{
+	u8 in[1] = { 0x10 }; /* enable oscillator */
+	ds2404_write_memory(dev, 0x201, 1, in);
+}
+
+static int ds2404_read_time(struct device *dev, struct rtc_time *dt)
+{
+	unsigned long time = 0;
+
+	ds2404_read_memory(dev, 0x203, 4, (u8 *)&time);
+	time = le32_to_cpu(time);
+
+	rtc_time_to_tm(time, dt);
+	return rtc_valid_tm(dt);
+}
+
+static int ds2404_set_mmss(struct device *dev, unsigned long secs)
+{
+	u32 time = cpu_to_le32(secs);
+	ds2404_write_memory(dev, 0x203, 4, (u8 *)&time);
+	return 0;
+}
+
+static const struct rtc_class_ops ds2404_rtc_ops = {
+	.read_time	= ds2404_read_time,
+	.set_mmss	= ds2404_set_mmss,
+};
+
+static int rtc_probe(struct platform_device *pdev)
+{
+	struct ds2404_platform_data *pdata = pdev->dev.platform_data;
+	struct ds2404 *chip;
+	int retval = -EBUSY;
+
+	chip = kzalloc(sizeof(struct ds2404), GFP_KERNEL);
+	if (!chip)
+		return -ENOMEM;
+
+	chip->ops = &ds2404_gpio_ops;
+
+	retval = chip->ops->map_io(chip, pdev, pdata);
+	if (retval)
+		goto err_chip;
+
+	dev_info(&pdev->dev, "using GPIOs RST:%d, CLK:%d, DQ:%d\n",
+		 chip->gpio[DS2404_RST].gpio, chip->gpio[DS2404_CLK].gpio,
+		 chip->gpio[DS2404_DQ].gpio);
+
+	platform_set_drvdata(pdev, chip);
+
+	chip->rtc = rtc_device_register("ds2404",
+				&pdev->dev, &ds2404_rtc_ops, THIS_MODULE);
+	if (IS_ERR(chip->rtc)) {
+		retval = PTR_ERR(chip->rtc);
+		goto err_io;
+	}
+
+	ds2404_enable_osc(&pdev->dev);
+	return 0;
+
+err_io:
+	chip->ops->unmap_io(chip);
+err_chip:
+	kfree(chip);
+	return retval;
+}
+
+static int rtc_remove(struct platform_device *dev)
+{
+	struct ds2404 *chip = platform_get_drvdata(dev);
+	struct rtc_device *rtc = chip->rtc;
+
+	if (rtc)
+		rtc_device_unregister(rtc);
+
+	chip->ops->unmap_io(chip);
+	kfree(chip);
+
+	return 0;
+}
+
+static struct platform_driver rtc_device_driver = {
+	.probe	= rtc_probe,
+	.remove = rtc_remove,
+	.driver = {
+		.name	= "ds2404",
+		.owner	= THIS_MODULE,
+	},
+};
+
+static __init int ds2404_init(void)
+{
+	return platform_driver_register(&rtc_device_driver);
+}
+
+static __exit void ds2404_exit(void)
+{
+	platform_driver_unregister(&rtc_device_driver);
+}
+
+module_init(ds2404_init);
+module_exit(ds2404_exit);
+
+MODULE_DESCRIPTION("DS2404 RTC");
+MODULE_AUTHOR("Sven Schnelle");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS("platform:ds2404");

include/linux/rtc-ds2404.h

@@ -0,0 +1,20 @@
+/*
+ * ds2404.h - platform data structure for the DS2404 RTC.
+ *
+ * This file is subject to the terms and conditions of the GNU General Public
+ * License.  See the file "COPYING" in the main directory of this archive
+ * for more details.
+ *
+ * Copyright (C) 2012 Sven Schnelle <svens@stackframe.org>
+ */
+
+#ifndef __LINUX_DS2404_H
+#define __LINUX_DS2404_H
+
+struct ds2404_platform_data {
+
+	unsigned int gpio_rst;
+	unsigned int gpio_clk;
+	unsigned int gpio_dq;
+};
+#endif