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1// SPDX-License-Identifier: GPL-2.02// Copyright (C) 2012 Sven Schnelle <svens@stackframe.org>3 4#include <linux/platform_device.h>5#include <linux/module.h>6#include <linux/init.h>7#include <linux/rtc.h>8#include <linux/types.h>9#include <linux/bcd.h>10#include <linux/delay.h>11#include <linux/gpio/consumer.h>12#include <linux/slab.h>13 14#include <linux/io.h>15 16#define DS2404_STATUS_REG 0x20017#define DS2404_CONTROL_REG 0x20118#define DS2404_RTC_REG 0x20219 20#define DS2404_WRITE_SCRATCHPAD_CMD 0x0f21#define DS2404_READ_SCRATCHPAD_CMD 0xaa22#define DS2404_COPY_SCRATCHPAD_CMD 0x5523#define DS2404_READ_MEMORY_CMD 0xf024 25#define DS2404_RST 026#define DS2404_CLK 127#define DS2404_DQ 228 29struct ds2404 {30 struct device *dev;31 struct gpio_desc *rst_gpiod;32 struct gpio_desc *clk_gpiod;33 struct gpio_desc *dq_gpiod;34 struct rtc_device *rtc;35};36 37static int ds2404_gpio_map(struct ds2404 *chip, struct platform_device *pdev)38{39 struct device *dev = &pdev->dev;40 41 /* This will de-assert RESET, declare this GPIO as GPIOD_ACTIVE_LOW */42 chip->rst_gpiod = devm_gpiod_get(dev, "rst", GPIOD_OUT_LOW);43 if (IS_ERR(chip->rst_gpiod))44 return PTR_ERR(chip->rst_gpiod);45 46 chip->clk_gpiod = devm_gpiod_get(dev, "clk", GPIOD_OUT_HIGH);47 if (IS_ERR(chip->clk_gpiod))48 return PTR_ERR(chip->clk_gpiod);49 50 chip->dq_gpiod = devm_gpiod_get(dev, "dq", GPIOD_ASIS);51 if (IS_ERR(chip->dq_gpiod))52 return PTR_ERR(chip->dq_gpiod);53 54 return 0;55}56 57static void ds2404_reset(struct ds2404 *chip)58{59 gpiod_set_value(chip->rst_gpiod, 1);60 udelay(1000);61 gpiod_set_value(chip->rst_gpiod, 0);62 gpiod_set_value(chip->clk_gpiod, 0);63 gpiod_direction_output(chip->dq_gpiod, 0);64 udelay(10);65}66 67static void ds2404_write_byte(struct ds2404 *chip, u8 byte)68{69 int i;70 71 gpiod_direction_output(chip->dq_gpiod, 1);72 for (i = 0; i < 8; i++) {73 gpiod_set_value(chip->dq_gpiod, byte & (1 << i));74 udelay(10);75 gpiod_set_value(chip->clk_gpiod, 1);76 udelay(10);77 gpiod_set_value(chip->clk_gpiod, 0);78 udelay(10);79 }80}81 82static u8 ds2404_read_byte(struct ds2404 *chip)83{84 int i;85 u8 ret = 0;86 87 gpiod_direction_input(chip->dq_gpiod);88 89 for (i = 0; i < 8; i++) {90 gpiod_set_value(chip->clk_gpiod, 0);91 udelay(10);92 if (gpiod_get_value(chip->dq_gpiod))93 ret |= 1 << i;94 gpiod_set_value(chip->clk_gpiod, 1);95 udelay(10);96 }97 return ret;98}99 100static void ds2404_read_memory(struct ds2404 *chip, u16 offset,101 int length, u8 *out)102{103 ds2404_reset(chip);104 ds2404_write_byte(chip, DS2404_READ_MEMORY_CMD);105 ds2404_write_byte(chip, offset & 0xff);106 ds2404_write_byte(chip, (offset >> 8) & 0xff);107 while (length--)108 *out++ = ds2404_read_byte(chip);109}110 111static void ds2404_write_memory(struct ds2404 *chip, u16 offset,112 int length, u8 *out)113{114 int i;115 u8 ta01, ta02, es;116 117 ds2404_reset(chip);118 ds2404_write_byte(chip, DS2404_WRITE_SCRATCHPAD_CMD);119 ds2404_write_byte(chip, offset & 0xff);120 ds2404_write_byte(chip, (offset >> 8) & 0xff);121 122 for (i = 0; i < length; i++)123 ds2404_write_byte(chip, out[i]);124 125 ds2404_reset(chip);126 ds2404_write_byte(chip, DS2404_READ_SCRATCHPAD_CMD);127 128 ta01 = ds2404_read_byte(chip);129 ta02 = ds2404_read_byte(chip);130 es = ds2404_read_byte(chip);131 132 for (i = 0; i < length; i++) {133 if (out[i] != ds2404_read_byte(chip)) {134 dev_err(chip->dev, "read invalid data\n");135 return;136 }137 }138 139 ds2404_reset(chip);140 ds2404_write_byte(chip, DS2404_COPY_SCRATCHPAD_CMD);141 ds2404_write_byte(chip, ta01);142 ds2404_write_byte(chip, ta02);143 ds2404_write_byte(chip, es);144 145 while (gpiod_get_value(chip->dq_gpiod))146 ;147}148 149static void ds2404_enable_osc(struct ds2404 *chip)150{151 u8 in[1] = { 0x10 }; /* enable oscillator */152 153 ds2404_write_memory(chip, 0x201, 1, in);154}155 156static int ds2404_read_time(struct device *dev, struct rtc_time *dt)157{158 struct ds2404 *chip = dev_get_drvdata(dev);159 unsigned long time = 0;160 __le32 hw_time = 0;161 162 ds2404_read_memory(chip, 0x203, 4, (u8 *)&hw_time);163 time = le32_to_cpu(hw_time);164 165 rtc_time64_to_tm(time, dt);166 return 0;167}168 169static int ds2404_set_time(struct device *dev, struct rtc_time *dt)170{171 struct ds2404 *chip = dev_get_drvdata(dev);172 u32 time = cpu_to_le32(rtc_tm_to_time64(dt));173 ds2404_write_memory(chip, 0x203, 4, (u8 *)&time);174 return 0;175}176 177static const struct rtc_class_ops ds2404_rtc_ops = {178 .read_time = ds2404_read_time,179 .set_time = ds2404_set_time,180};181 182static int rtc_probe(struct platform_device *pdev)183{184 struct ds2404 *chip;185 int retval = -EBUSY;186 187 chip = devm_kzalloc(&pdev->dev, sizeof(struct ds2404), GFP_KERNEL);188 if (!chip)189 return -ENOMEM;190 191 chip->dev = &pdev->dev;192 193 chip->rtc = devm_rtc_allocate_device(&pdev->dev);194 if (IS_ERR(chip->rtc))195 return PTR_ERR(chip->rtc);196 197 retval = ds2404_gpio_map(chip, pdev);198 if (retval)199 return retval;200 201 platform_set_drvdata(pdev, chip);202 203 chip->rtc->ops = &ds2404_rtc_ops;204 chip->rtc->range_max = U32_MAX;205 206 retval = devm_rtc_register_device(chip->rtc);207 if (retval)208 return retval;209 210 ds2404_enable_osc(chip);211 return 0;212}213 214static struct platform_driver rtc_device_driver = {215 .probe = rtc_probe,216 .driver = {217 .name = "ds2404",218 },219};220module_platform_driver(rtc_device_driver);221 222MODULE_DESCRIPTION("DS2404 RTC");223MODULE_AUTHOR("Sven Schnelle");224MODULE_LICENSE("GPL");225MODULE_ALIAS("platform:ds2404");226