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>

4 files changed, 333 insertions, 0 deletions

diff --git a/drivers/rtc/Kconfig b/drivers/rtc/Kconfig
index a4a805c273bb..d4681c97f7cc 100644
--- a/drivers/rtc/Kconfig
+++ b/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
diff --git a/drivers/rtc/Makefile b/drivers/rtc/Makefile
index 0d5b2b66f90d..7ecdb2983dde 100644
--- a/drivers/rtc/Makefile
+++ b/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
diff --git a/drivers/rtc/rtc-ds2404.c b/drivers/rtc/rtc-ds2404.c
new file mode 100644
index 000000000000..5ea9df7c8c31
--- /dev/null
+++ b/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");
diff --git a/include/linux/rtc-ds2404.h b/include/linux/rtc-ds2404.h
new file mode 100644
index 000000000000..22c53825528f
--- /dev/null
+++ b/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