Sven Schnelle | 7418a11 | 2012-10-04 17:13:47 -0700 | [diff] [blame^] | 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 | printk(KERN_ERR "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 | printk(KERN_ERR "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 = pdev->dev.platform_data; |
| 228 | struct ds2404 *chip; |
| 229 | int retval = -EBUSY; |
| 230 | |
| 231 | chip = kzalloc(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 = rtc_device_register("ds2404", |
| 248 | &pdev->dev, &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 | kfree(chip); |
| 261 | return retval; |
| 262 | } |
| 263 | |
| 264 | static int rtc_remove(struct platform_device *dev) |
| 265 | { |
| 266 | struct ds2404 *chip = platform_get_drvdata(dev); |
| 267 | struct rtc_device *rtc = chip->rtc; |
| 268 | |
| 269 | if (rtc) |
| 270 | rtc_device_unregister(rtc); |
| 271 | |
| 272 | chip->ops->unmap_io(chip); |
| 273 | kfree(chip); |
| 274 | |
| 275 | return 0; |
| 276 | } |
| 277 | |
| 278 | static struct platform_driver rtc_device_driver = { |
| 279 | .probe = rtc_probe, |
| 280 | .remove = rtc_remove, |
| 281 | .driver = { |
| 282 | .name = "ds2404", |
| 283 | .owner = THIS_MODULE, |
| 284 | }, |
| 285 | }; |
| 286 | |
| 287 | static __init int ds2404_init(void) |
| 288 | { |
| 289 | return platform_driver_register(&rtc_device_driver); |
| 290 | } |
| 291 | |
| 292 | static __exit void ds2404_exit(void) |
| 293 | { |
| 294 | platform_driver_unregister(&rtc_device_driver); |
| 295 | } |
| 296 | |
| 297 | module_init(ds2404_init); |
| 298 | module_exit(ds2404_exit); |
| 299 | |
| 300 | MODULE_DESCRIPTION("DS2404 RTC"); |
| 301 | MODULE_AUTHOR("Sven Schnelle"); |
| 302 | MODULE_LICENSE("GPL"); |
| 303 | MODULE_ALIAS("platform:ds2404"); |