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13bfa94225
The real-time clock is a 5-byte binary counter. It is incremented 256 times per second. The least significant byte is a count of fractional seconds. The upper four bytes are a count of seconds. The realtime clock can accumulate 136 years of seconds before rolling over. Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
289 lines
6.4 KiB
C
289 lines
6.4 KiB
C
/*
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* Copyright (C) 2012 Sven Schnelle <svens@stackframe.org>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*
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*/
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#include <linux/platform_device.h>
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#include <linux/module.h>
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#include <linux/init.h>
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#include <linux/rtc.h>
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#include <linux/types.h>
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#include <linux/bcd.h>
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#include <linux/platform_data/rtc-ds2404.h>
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#include <linux/delay.h>
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#include <linux/gpio.h>
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#include <linux/slab.h>
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#include <linux/io.h>
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#define DS2404_STATUS_REG 0x200
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#define DS2404_CONTROL_REG 0x201
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#define DS2404_RTC_REG 0x202
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#define DS2404_WRITE_SCRATCHPAD_CMD 0x0f
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#define DS2404_READ_SCRATCHPAD_CMD 0xaa
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#define DS2404_COPY_SCRATCHPAD_CMD 0x55
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#define DS2404_READ_MEMORY_CMD 0xf0
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struct ds2404;
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struct ds2404_chip_ops {
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int (*map_io)(struct ds2404 *chip, struct platform_device *pdev,
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struct ds2404_platform_data *pdata);
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void (*unmap_io)(struct ds2404 *chip);
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};
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#define DS2404_RST 0
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#define DS2404_CLK 1
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#define DS2404_DQ 2
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struct ds2404_gpio {
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const char *name;
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unsigned int gpio;
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};
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struct ds2404 {
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struct ds2404_gpio *gpio;
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const struct ds2404_chip_ops *ops;
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struct rtc_device *rtc;
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};
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static struct ds2404_gpio ds2404_gpio[] = {
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{ "RTC RST", 0 },
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{ "RTC CLK", 0 },
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{ "RTC DQ", 0 },
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};
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static int ds2404_gpio_map(struct ds2404 *chip, struct platform_device *pdev,
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struct ds2404_platform_data *pdata)
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{
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int i, err;
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ds2404_gpio[DS2404_RST].gpio = pdata->gpio_rst;
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ds2404_gpio[DS2404_CLK].gpio = pdata->gpio_clk;
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ds2404_gpio[DS2404_DQ].gpio = pdata->gpio_dq;
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for (i = 0; i < ARRAY_SIZE(ds2404_gpio); i++) {
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err = gpio_request(ds2404_gpio[i].gpio, ds2404_gpio[i].name);
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if (err) {
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dev_err(&pdev->dev, "error mapping gpio %s: %d\n",
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ds2404_gpio[i].name, err);
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goto err_request;
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}
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if (i != DS2404_DQ)
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gpio_direction_output(ds2404_gpio[i].gpio, 1);
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}
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chip->gpio = ds2404_gpio;
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return 0;
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err_request:
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while (--i >= 0)
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gpio_free(ds2404_gpio[i].gpio);
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return err;
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}
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static void ds2404_gpio_unmap(struct ds2404 *chip)
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{
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int i;
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for (i = 0; i < ARRAY_SIZE(ds2404_gpio); i++)
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gpio_free(ds2404_gpio[i].gpio);
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}
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static const struct ds2404_chip_ops ds2404_gpio_ops = {
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.map_io = ds2404_gpio_map,
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.unmap_io = ds2404_gpio_unmap,
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};
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static void ds2404_reset(struct device *dev)
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{
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gpio_set_value(ds2404_gpio[DS2404_RST].gpio, 0);
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udelay(1000);
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gpio_set_value(ds2404_gpio[DS2404_RST].gpio, 1);
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gpio_set_value(ds2404_gpio[DS2404_CLK].gpio, 0);
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gpio_direction_output(ds2404_gpio[DS2404_DQ].gpio, 0);
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udelay(10);
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}
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static void ds2404_write_byte(struct device *dev, u8 byte)
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{
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int i;
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gpio_direction_output(ds2404_gpio[DS2404_DQ].gpio, 1);
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for (i = 0; i < 8; i++) {
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gpio_set_value(ds2404_gpio[DS2404_DQ].gpio, byte & (1 << i));
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udelay(10);
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gpio_set_value(ds2404_gpio[DS2404_CLK].gpio, 1);
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udelay(10);
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gpio_set_value(ds2404_gpio[DS2404_CLK].gpio, 0);
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udelay(10);
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}
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}
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static u8 ds2404_read_byte(struct device *dev)
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{
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int i;
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u8 ret = 0;
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gpio_direction_input(ds2404_gpio[DS2404_DQ].gpio);
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for (i = 0; i < 8; i++) {
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gpio_set_value(ds2404_gpio[DS2404_CLK].gpio, 0);
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udelay(10);
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if (gpio_get_value(ds2404_gpio[DS2404_DQ].gpio))
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ret |= 1 << i;
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gpio_set_value(ds2404_gpio[DS2404_CLK].gpio, 1);
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udelay(10);
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}
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return ret;
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}
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static void ds2404_read_memory(struct device *dev, u16 offset,
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int length, u8 *out)
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{
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ds2404_reset(dev);
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ds2404_write_byte(dev, DS2404_READ_MEMORY_CMD);
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ds2404_write_byte(dev, offset & 0xff);
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ds2404_write_byte(dev, (offset >> 8) & 0xff);
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while (length--)
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*out++ = ds2404_read_byte(dev);
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}
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static void ds2404_write_memory(struct device *dev, u16 offset,
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int length, u8 *out)
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{
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int i;
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u8 ta01, ta02, es;
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ds2404_reset(dev);
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ds2404_write_byte(dev, DS2404_WRITE_SCRATCHPAD_CMD);
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ds2404_write_byte(dev, offset & 0xff);
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ds2404_write_byte(dev, (offset >> 8) & 0xff);
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for (i = 0; i < length; i++)
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ds2404_write_byte(dev, out[i]);
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ds2404_reset(dev);
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ds2404_write_byte(dev, DS2404_READ_SCRATCHPAD_CMD);
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ta01 = ds2404_read_byte(dev);
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ta02 = ds2404_read_byte(dev);
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es = ds2404_read_byte(dev);
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for (i = 0; i < length; i++) {
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if (out[i] != ds2404_read_byte(dev)) {
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dev_err(dev, "read invalid data\n");
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return;
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}
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}
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ds2404_reset(dev);
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ds2404_write_byte(dev, DS2404_COPY_SCRATCHPAD_CMD);
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ds2404_write_byte(dev, ta01);
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ds2404_write_byte(dev, ta02);
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ds2404_write_byte(dev, es);
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gpio_direction_input(ds2404_gpio[DS2404_DQ].gpio);
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while (gpio_get_value(ds2404_gpio[DS2404_DQ].gpio))
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;
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}
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static void ds2404_enable_osc(struct device *dev)
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{
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u8 in[1] = { 0x10 }; /* enable oscillator */
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ds2404_write_memory(dev, 0x201, 1, in);
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}
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static int ds2404_read_time(struct device *dev, struct rtc_time *dt)
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{
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unsigned long time = 0;
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ds2404_read_memory(dev, 0x203, 4, (u8 *)&time);
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time = le32_to_cpu(time);
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rtc_time_to_tm(time, dt);
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return 0;
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}
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static int ds2404_set_mmss(struct device *dev, unsigned long secs)
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{
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u32 time = cpu_to_le32(secs);
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ds2404_write_memory(dev, 0x203, 4, (u8 *)&time);
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return 0;
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}
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static const struct rtc_class_ops ds2404_rtc_ops = {
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.read_time = ds2404_read_time,
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.set_mmss = ds2404_set_mmss,
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};
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static int rtc_probe(struct platform_device *pdev)
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{
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struct ds2404_platform_data *pdata = dev_get_platdata(&pdev->dev);
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struct ds2404 *chip;
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int retval = -EBUSY;
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chip = devm_kzalloc(&pdev->dev, sizeof(struct ds2404), GFP_KERNEL);
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if (!chip)
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return -ENOMEM;
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chip->ops = &ds2404_gpio_ops;
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chip->rtc = devm_rtc_allocate_device(&pdev->dev);
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if (IS_ERR(chip->rtc))
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return PTR_ERR(chip->rtc);
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retval = chip->ops->map_io(chip, pdev, pdata);
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if (retval)
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goto err_chip;
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dev_info(&pdev->dev, "using GPIOs RST:%d, CLK:%d, DQ:%d\n",
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chip->gpio[DS2404_RST].gpio, chip->gpio[DS2404_CLK].gpio,
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chip->gpio[DS2404_DQ].gpio);
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platform_set_drvdata(pdev, chip);
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chip->rtc->ops = &ds2404_rtc_ops;
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chip->rtc->range_max = U32_MAX;
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retval = rtc_register_device(chip->rtc);
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if (retval)
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goto err_io;
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ds2404_enable_osc(&pdev->dev);
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return 0;
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err_io:
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chip->ops->unmap_io(chip);
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err_chip:
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return retval;
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}
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static int rtc_remove(struct platform_device *dev)
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{
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struct ds2404 *chip = platform_get_drvdata(dev);
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chip->ops->unmap_io(chip);
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return 0;
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}
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static struct platform_driver rtc_device_driver = {
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.probe = rtc_probe,
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.remove = rtc_remove,
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.driver = {
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.name = "ds2404",
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},
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};
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module_platform_driver(rtc_device_driver);
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MODULE_DESCRIPTION("DS2404 RTC");
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MODULE_AUTHOR("Sven Schnelle");
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MODULE_LICENSE("GPL");
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MODULE_ALIAS("platform:ds2404");
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