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Subject[PATCH] rtc: add support for maxim dallas ds1682
Date
From: Venkat Prashanth B U <venkat.prashanth2498@gmail.com>

Add supporting driver for Dallas Semiconductor
DS1682 2 wire total elapsed time recorder.

Signed-off-by: Venkat Prashanth B U <venkat.prashanth2498@gmail.com>
---
drivers/rtc/rtc-ds1682.c | 284 +++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 284 insertions(+)

diff --git a/drivers/rtc/rtc-ds1682.c b/drivers/rtc/rtc-ds1682.c
index e69de29..a21c94d 100644
--- a/drivers/rtc/rtc-ds1682.c
+++ b/drivers/rtc/rtc-ds1682.c
@@ -0,0 +1,284 @@
+/* Driver for Dallas Semiconductor DS1682 2 wire total elapsed
+ * time recorder
+ *
+ * Author : Venkat Prashanth B U <venkat.prashanth2498@gmail.com>
+ *
+ * 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/delay.h>
+#include <linux/gpio.h>
+#include <linux/slab.h>
+#include <linux/io.h>
+
+#define DS1682_READ_MEMORY_CMD 0x1D
+
+#ifndef __LINUX_DS1682_H
+#define __LINUX_DS1682_H
+
+const struct ds1682_platform_data {
+
+ unsigned int gpio_rst;
+ unsigned int gpio_clk;
+ unsigned int gpio_dq;
+};
+#endif
+
+const struct ds1682;
+
+const struct ds1682_chip_ops {
+ int (*map_io)(const struct ds1682 *chip, struct platform_device *pdev,
+ const struct ds1682_platform_data *pdata);
+ void (*unmap_io)(const struct ds1682 *chip);
+};
+
+#define DS1682_RST 0
+#define DS1682_CLK 1
+#define DS1682_DQ 2
+
+const struct ds1682_gpio {
+ const char *name;
+ unsigned int gpio;
+};
+
+const struct ds1682 {
+ const struct ds1682_gpio *gpio;
+ const struct ds1682_chip_ops *ops;
+ const struct rtc_device *rtc;
+};
+
+const struct ds1682_gpio ds1682_gpio[] = {
+ { "RTC RST", 0 },
+ { "RTC CLK", 0 },
+ { "RTC DQ", 0 },
+};
+
+int ds1682_gpio_map(const struct ds1682 *chip, struct platform_device *pdev,
+ const struct ds1682_platform_data *pdata)
+{
+ int i, err;
+
+ ds1682_gpio[DS1682_RST].gpio = pdata->gpio_rst;
+ ds1682_gpio[DS1682_CLK].gpio = pdata->gpio_clk;
+ ds1682_gpio[DS1682_DQ].gpio = pdata->gpio_dq;
+
+ for (i = 0; i < ARRAY_SIZE(ds1682_gpio); i++) {
+ err = gpio_request(ds1682_gpio[i].gpio, ds1682_gpio[i].name);
+ if (err) {
+ dev_err(&pdev->dev, "error mapping gpio %s: %d\n",
+ ds1682_gpio[i].name, err);
+ goto err_request;
+ }
+ if (i != DS1682_DQ)
+ gpio_direction_output(ds1682_gpio[i].gpio, 1);
+ }
+
+ chip->gpio = ds1682_gpio;
+ return 0;
+
+err_request:
+ while (--i >= 0)
+ gpio_free(ds1682_gpio[i].gpio);
+ return err;
+}
+
+static void ds1682_gpio_unmap(const struct ds1682 *chip)
+{
+ int i;
+
+ for (i = 0; i < ARRAY_SIZE(ds1682_gpio); i++)
+ gpio_free(ds1682_gpio[i].gpio);
+}
+
+static const struct ds1682_chip_ops ds1682_gpio_ops = {
+ .map_io = ds1682_gpio_map,
+ .unmap_io = ds1682_gpio_unmap,
+};
+
+static void ds1682_reset(const struct device *dev)
+{
+ gpio_set_value(ds1682_gpio[DS1682_RST].gpio, 0);
+ udelay(1000);
+ gpio_set_value(ds1682_gpio[DS1682_RST].gpio, 1);
+ gpio_set_value(ds1682_gpio[DS1682_CLK].gpio, 0);
+ gpio_direction_output(ds1682_gpio[DS1682_DQ].gpio, 0);
+ udelay(10);
+}
+
+static void ds1682_write_byte(const struct device *dev, u8 byte)
+{
+ int i;
+
+ gpio_direction_output(ds1682_gpio[DS1682_DQ].gpio, 1);
+ for (i = 0; i < 8; i++) {
+ gpio_set_value(ds1682_gpio[DS1682_DQ].gpio, byte & (1 << i));
+ udelay(10);
+ gpio_set_value(ds1682_gpio[DS1682_CLK].gpio, 1);
+ udelay(10);
+ gpio_set_value(ds1682_gpio[DS1682_CLK].gpio, 0);
+ udelay(10);
+ }
+}
+
+static u8 ds1682_read_byte(const struct device *dev)
+{
+ int i;
+ u8 ret = 0;
+
+ gpio_direction_input(ds1682_gpio[DS1682_DQ].gpio);
+
+ for (i = 0; i < 8; i++) {
+ gpio_set_value(ds1682_gpio[DS1682_CLK].gpio, 0);
+ udelay(10);
+ if (gpio_get_value(ds1682_gpio[DS1682_DQ].gpio))
+ ret |= 1 << i;
+ gpio_set_value(ds1682_gpio[DS1682_CLK].gpio, 1);
+ udelay(10);
+ }
+ return ret;
+}
+
+static void ds1682_read_memory(const struct device *dev, u16 offset,
+ int length, u8 *out)
+{
+ ds1682_reset(dev);
+ ds1682_write_byte(dev, DS1682_READ_MEMORY_CMD);
+ ds1682_write_byte(dev, offset & 0xff);
+ ds1682_write_byte(dev, (offset >> 8) & 0xff);
+ while (length--)
+ *out++ = ds1682_read_byte(dev);
+}
+
+static void ds1682_write_memory(const struct device *dev, u16 offset,
+ int length, u8 *out)
+{
+ int i;
+ u8 ta01, ta02, es;
+
+ ds1682_reset(dev);
+ ds1682_write_byte(dev, offset & 0xff);
+ ds1682_write_byte(dev, (offset >> 8) & 0xff);
+
+ for (i = 0; i < length; i++)
+ ds1682_write_byte(dev, out[i]);
+
+ ds1682_reset(dev);
+ ta01 = ds1682_read_byte(dev);
+ ta02 = ds1682_read_byte(dev);
+ es = ds1682_read_byte(dev);
+
+ for (i = 0; i < length; i++) {
+ if (out[i] != ds1682_read_byte(dev)) {
+ dev_err(dev, "read invalid data\n");
+ return;
+ }
+ }
+
+ ds1682_reset(dev);
+ ds1682_write_byte(dev, ta01);
+ ds1682_write_byte(dev, ta02);
+ ds1682_write_byte(dev, es);
+ gpio_direction_input(ds1682_gpio[DS1682_DQ].gpio);
+while (gpio_get_value(ds1682_gpio[DS1682_DQ].gpio))
+}
+
+static void ds1682_enable_osc(const struct device *dev)
+{
+ u8 in[1] = { 0x10 }; /* enable oscillator */
+
+ ds1682_write_memory(dev, 0x201, 1, in);
+}
+
+static int ds1682_read_time(const struct device *dev, struct rtc_time *dt)
+{
+ unsigned long time = 0;
+
+ ds1682_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 ds1682_set_mmss(const struct device *dev, unsigned long secs)
+{
+ u32 time = cpu_to_le32(secs);
+
+ ds1682_write_memory(dev, 0x203, 4, (u8 *)&time);
+ return 0;
+}
+
+static const struct rtc_class_ops ds1682_rtc_ops = {
+ .read_time = ds1682_read_time,
+ .set_mmss = ds1682_set_mmss,
+};
+
+static int rtc_probe(const struct platform_device *pdev)
+{
+const struct ds1682_platform_data *pdata = dev_get_platdata(&pdev->dev);
+ const struct ds1682 *chip;
+ int retval = -EBUSY;
+
+chip = devm_kzalloc(&pdev->dev, sizeof(const struct ds1682), GFP_KERNEL);
+ if (!chip)
+ return -ENOMEM;
+
+ chip->ops = &ds1682_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[DS1682_RST].gpio, chip->gpio[DS1682_CLK].gpio,
+ chip->gpio[DS1682_DQ].gpio);
+
+ platform_set_drvdata(pdev, chip);
+
+ chip->rtc = devm_rtc_device_register(&pdev->dev, "ds1682",
+ &ds1682_rtc_ops, THIS_MODULE);
+ if (IS_ERR(chip->rtc)) {
+ retval = PTR_ERR(chip->rtc);
+ goto err_io;
+ }
+
+ ds1682_enable_osc(&pdev->dev);
+ return 0;
+
+err_io:
+ chip->ops->unmap_io(chip);
+err_chip:
+ return retval;
+}
+
+static int rtc_remove(const struct platform_device *dev)
+{
+const struct ds1682 *chip = platform_get_drvdata(dev);
+
+ chip->ops->unmap_io(chip);
+
+ return 0;
+}
+
+const struct platform_driver rtc_device_driver = {
+ .probe = rtc_probe,
+ .remove = rtc_remove,
+ .driver = {
+ .name = "ds1682",
+ },
+};
+module_platform_driver(rtc_device_driver);
+
+MODULE_DESCRIPTION("DS1682 Total Elapsed Time Recorder");
+MODULE_AUTHOR("Venkat Prashanth B U <venkat.prashanth2498@gmail.com>");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS("platform:ds1682");
--
1.9.1

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