Version:  2.0.40 2.2.26 2.4.37 3.2 3.3 3.4 3.5 3.6 3.7 3.8 3.9 3.10 3.11 3.12 3.13 3.14 3.15 3.16 3.17 3.18

Linux/drivers/rtc/rtc-ds2404.c

  1 /*
  2  * Copyright (C) 2012 Sven Schnelle <svens@stackframe.org>
  3  *
  4  * This program is free software; you can redistribute it and/or modify
  5  * it under the terms of the GNU General Public License version 2 as
  6  * published by the Free Software Foundation.
  7  *
  8  */
  9 
 10 #include <linux/platform_device.h>
 11 #include <linux/module.h>
 12 #include <linux/init.h>
 13 #include <linux/rtc.h>
 14 #include <linux/types.h>
 15 #include <linux/bcd.h>
 16 #include <linux/rtc-ds2404.h>
 17 #include <linux/delay.h>
 18 #include <linux/gpio.h>
 19 #include <linux/slab.h>
 20 
 21 #include <linux/io.h>
 22 
 23 #define DS2404_STATUS_REG 0x200
 24 #define DS2404_CONTROL_REG 0x201
 25 #define DS2404_RTC_REG 0x202
 26 
 27 #define DS2404_WRITE_SCRATCHPAD_CMD 0x0f
 28 #define DS2404_READ_SCRATCHPAD_CMD 0xaa
 29 #define DS2404_COPY_SCRATCHPAD_CMD 0x55
 30 #define DS2404_READ_MEMORY_CMD 0xf0
 31 
 32 struct ds2404;
 33 
 34 struct ds2404_chip_ops {
 35         int (*map_io)(struct ds2404 *chip, struct platform_device *pdev,
 36                       struct ds2404_platform_data *pdata);
 37         void (*unmap_io)(struct ds2404 *chip);
 38 };
 39 
 40 #define DS2404_RST      0
 41 #define DS2404_CLK      1
 42 #define DS2404_DQ       2
 43 
 44 struct ds2404_gpio {
 45         const char *name;
 46         unsigned int gpio;
 47 };
 48 
 49 struct ds2404 {
 50         struct ds2404_gpio *gpio;
 51         struct ds2404_chip_ops *ops;
 52         struct rtc_device *rtc;
 53 };
 54 
 55 static struct ds2404_gpio ds2404_gpio[] = {
 56         { "RTC RST", 0 },
 57         { "RTC CLK", 0 },
 58         { "RTC DQ", 0 },
 59 };
 60 
 61 static int ds2404_gpio_map(struct ds2404 *chip, struct platform_device *pdev,
 62                           struct ds2404_platform_data *pdata)
 63 {
 64         int i, err;
 65 
 66         ds2404_gpio[DS2404_RST].gpio = pdata->gpio_rst;
 67         ds2404_gpio[DS2404_CLK].gpio = pdata->gpio_clk;
 68         ds2404_gpio[DS2404_DQ].gpio = pdata->gpio_dq;
 69 
 70         for (i = 0; i < ARRAY_SIZE(ds2404_gpio); i++) {
 71                 err = gpio_request(ds2404_gpio[i].gpio, ds2404_gpio[i].name);
 72                 if (err) {
 73                         dev_err(&pdev->dev, "error mapping gpio %s: %d\n",
 74                                 ds2404_gpio[i].name, err);
 75                         goto err_request;
 76                 }
 77                 if (i != DS2404_DQ)
 78                         gpio_direction_output(ds2404_gpio[i].gpio, 1);
 79         }
 80 
 81         chip->gpio = ds2404_gpio;
 82         return 0;
 83 
 84 err_request:
 85         while (--i >= 0)
 86                 gpio_free(ds2404_gpio[i].gpio);
 87         return err;
 88 }
 89 
 90 static void ds2404_gpio_unmap(struct ds2404 *chip)
 91 {
 92         int i;
 93 
 94         for (i = 0; i < ARRAY_SIZE(ds2404_gpio); i++)
 95                 gpio_free(ds2404_gpio[i].gpio);
 96 }
 97 
 98 static struct ds2404_chip_ops ds2404_gpio_ops = {
 99         .map_io         = ds2404_gpio_map,
100         .unmap_io       = ds2404_gpio_unmap,
101 };
102 
103 static void ds2404_reset(struct device *dev)
104 {
105         gpio_set_value(ds2404_gpio[DS2404_RST].gpio, 0);
106         udelay(1000);
107         gpio_set_value(ds2404_gpio[DS2404_RST].gpio, 1);
108         gpio_set_value(ds2404_gpio[DS2404_CLK].gpio, 0);
109         gpio_direction_output(ds2404_gpio[DS2404_DQ].gpio, 0);
110         udelay(10);
111 }
112 
113 static void ds2404_write_byte(struct device *dev, u8 byte)
114 {
115         int i;
116 
117         gpio_direction_output(ds2404_gpio[DS2404_DQ].gpio, 1);
118         for (i = 0; i < 8; i++) {
119                 gpio_set_value(ds2404_gpio[DS2404_DQ].gpio, byte & (1 << i));
120                 udelay(10);
121                 gpio_set_value(ds2404_gpio[DS2404_CLK].gpio, 1);
122                 udelay(10);
123                 gpio_set_value(ds2404_gpio[DS2404_CLK].gpio, 0);
124                 udelay(10);
125         }
126 }
127 
128 static u8 ds2404_read_byte(struct device *dev)
129 {
130         int i;
131         u8 ret = 0;
132 
133         gpio_direction_input(ds2404_gpio[DS2404_DQ].gpio);
134 
135         for (i = 0; i < 8; i++) {
136                 gpio_set_value(ds2404_gpio[DS2404_CLK].gpio, 0);
137                 udelay(10);
138                 if (gpio_get_value(ds2404_gpio[DS2404_DQ].gpio))
139                         ret |= 1 << i;
140                 gpio_set_value(ds2404_gpio[DS2404_CLK].gpio, 1);
141                 udelay(10);
142         }
143         return ret;
144 }
145 
146 static void ds2404_read_memory(struct device *dev, u16 offset,
147                                int length, u8 *out)
148 {
149         ds2404_reset(dev);
150         ds2404_write_byte(dev, DS2404_READ_MEMORY_CMD);
151         ds2404_write_byte(dev, offset & 0xff);
152         ds2404_write_byte(dev, (offset >> 8) & 0xff);
153         while (length--)
154                 *out++ = ds2404_read_byte(dev);
155 }
156 
157 static void ds2404_write_memory(struct device *dev, u16 offset,
158                                 int length, u8 *out)
159 {
160         int i;
161         u8 ta01, ta02, es;
162 
163         ds2404_reset(dev);
164         ds2404_write_byte(dev, DS2404_WRITE_SCRATCHPAD_CMD);
165         ds2404_write_byte(dev, offset & 0xff);
166         ds2404_write_byte(dev, (offset >> 8) & 0xff);
167 
168         for (i = 0; i < length; i++)
169                 ds2404_write_byte(dev, out[i]);
170 
171         ds2404_reset(dev);
172         ds2404_write_byte(dev, DS2404_READ_SCRATCHPAD_CMD);
173 
174         ta01 = ds2404_read_byte(dev);
175         ta02 = ds2404_read_byte(dev);
176         es = ds2404_read_byte(dev);
177 
178         for (i = 0; i < length; i++) {
179                 if (out[i] != ds2404_read_byte(dev)) {
180                         dev_err(dev, "read invalid data\n");
181                         return;
182                 }
183         }
184 
185         ds2404_reset(dev);
186         ds2404_write_byte(dev, DS2404_COPY_SCRATCHPAD_CMD);
187         ds2404_write_byte(dev, ta01);
188         ds2404_write_byte(dev, ta02);
189         ds2404_write_byte(dev, es);
190 
191         gpio_direction_input(ds2404_gpio[DS2404_DQ].gpio);
192         while (gpio_get_value(ds2404_gpio[DS2404_DQ].gpio))
193                 ;
194 }
195 
196 static void ds2404_enable_osc(struct device *dev)
197 {
198         u8 in[1] = { 0x10 }; /* enable oscillator */
199         ds2404_write_memory(dev, 0x201, 1, in);
200 }
201 
202 static int ds2404_read_time(struct device *dev, struct rtc_time *dt)
203 {
204         unsigned long time = 0;
205 
206         ds2404_read_memory(dev, 0x203, 4, (u8 *)&time);
207         time = le32_to_cpu(time);
208 
209         rtc_time_to_tm(time, dt);
210         return rtc_valid_tm(dt);
211 }
212 
213 static int ds2404_set_mmss(struct device *dev, unsigned long secs)
214 {
215         u32 time = cpu_to_le32(secs);
216         ds2404_write_memory(dev, 0x203, 4, (u8 *)&time);
217         return 0;
218 }
219 
220 static const struct rtc_class_ops ds2404_rtc_ops = {
221         .read_time      = ds2404_read_time,
222         .set_mmss       = ds2404_set_mmss,
223 };
224 
225 static int rtc_probe(struct platform_device *pdev)
226 {
227         struct ds2404_platform_data *pdata = dev_get_platdata(&pdev->dev);
228         struct ds2404 *chip;
229         int retval = -EBUSY;
230 
231         chip = devm_kzalloc(&pdev->dev, sizeof(struct ds2404), GFP_KERNEL);
232         if (!chip)
233                 return -ENOMEM;
234 
235         chip->ops = &ds2404_gpio_ops;
236 
237         retval = chip->ops->map_io(chip, pdev, pdata);
238         if (retval)
239                 goto err_chip;
240 
241         dev_info(&pdev->dev, "using GPIOs RST:%d, CLK:%d, DQ:%d\n",
242                  chip->gpio[DS2404_RST].gpio, chip->gpio[DS2404_CLK].gpio,
243                  chip->gpio[DS2404_DQ].gpio);
244 
245         platform_set_drvdata(pdev, chip);
246 
247         chip->rtc = devm_rtc_device_register(&pdev->dev, "ds2404",
248                                         &ds2404_rtc_ops, THIS_MODULE);
249         if (IS_ERR(chip->rtc)) {
250                 retval = PTR_ERR(chip->rtc);
251                 goto err_io;
252         }
253 
254         ds2404_enable_osc(&pdev->dev);
255         return 0;
256 
257 err_io:
258         chip->ops->unmap_io(chip);
259 err_chip:
260         return retval;
261 }
262 
263 static int rtc_remove(struct platform_device *dev)
264 {
265         struct ds2404 *chip = platform_get_drvdata(dev);
266 
267         chip->ops->unmap_io(chip);
268 
269         return 0;
270 }
271 
272 static struct platform_driver rtc_device_driver = {
273         .probe  = rtc_probe,
274         .remove = rtc_remove,
275         .driver = {
276                 .name   = "ds2404",
277                 .owner  = THIS_MODULE,
278         },
279 };
280 module_platform_driver(rtc_device_driver);
281 
282 MODULE_DESCRIPTION("DS2404 RTC");
283 MODULE_AUTHOR("Sven Schnelle");
284 MODULE_LICENSE("GPL");
285 MODULE_ALIAS("platform:ds2404");
286 

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