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