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Release 4.14 drivers/rtc/rtc-ds2404.c

Directory: drivers/rtc
/*
 * 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/platform_data/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;
	
const 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) { dev_err(&pdev->dev, "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; }

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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); }

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static const 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); }

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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); } }

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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; }

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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); }

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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)) { dev_err(dev, "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)) ; }

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static void ds2404_enable_osc(struct device *dev) { u8 in[1] = { 0x10 }; /* enable oscillator */ ds2404_write_memory(dev, 0x201, 1, in); }

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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); }

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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; }

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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 = dev_get_platdata(&pdev->dev); struct ds2404 *chip; int retval = -EBUSY; chip = devm_kzalloc(&pdev->dev, 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 = devm_rtc_device_register(&pdev->dev, "ds2404", &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: return retval; }

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static int rtc_remove(struct platform_device *dev) { struct ds2404 *chip = platform_get_drvdata(dev); chip->ops->unmap_io(chip); return 0; }

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static struct platform_driver rtc_device_driver = { .probe = rtc_probe, .remove = rtc_remove, .driver = { .name = "ds2404", }, }; module_platform_driver(rtc_device_driver); MODULE_DESCRIPTION("DS2404 RTC"); MODULE_AUTHOR("Sven Schnelle"); MODULE_LICENSE("GPL"); MODULE_ALIAS("platform:ds2404");

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Directory: drivers/rtc
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