1 // SPDX-License-Identifier: GPL-2.0 2 // 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/platform_data/rtc-ds2404.h> 11 #include <linux/delay.h> 12 #include <linux/gpio.h> 13 #include <linux/slab.h> 14 15 #include <linux/io.h> 16 17 #define DS2404_STATUS_REG 0x200 18 #define DS2404_CONTROL_REG 0x201 19 #define DS2404_RTC_REG 0x202 20 21 #define DS2404_WRITE_SCRATCHPAD_CMD 0x0f 22 #define DS2404_READ_SCRATCHPAD_CMD 0xaa 23 #define DS2404_COPY_SCRATCHPAD_CMD 0x55 24 #define DS2404_READ_MEMORY_CMD 0xf0 25 26 #define DS2404_RST 0 27 #define DS2404_CLK 1 28 #define DS2404_DQ 2 29 30 struct ds2404_gpio { 31 const char *name; 32 unsigned int gpio; 33 }; 34 35 struct ds2404 { 36 struct ds2404_gpio *gpio; 37 struct rtc_device *rtc; 38 }; 39 40 static struct ds2404_gpio ds2404_gpio[] = { 41 { "RTC RST", 0 }, 42 { "RTC CLK", 0 }, 43 { "RTC DQ", 0 }, 44 }; 45 46 static int ds2404_gpio_map(struct ds2404 *chip, struct platform_device *pdev, 47 struct ds2404_platform_data *pdata) 48 { 49 int i, err; 50 51 ds2404_gpio[DS2404_RST].gpio = pdata->gpio_rst; 52 ds2404_gpio[DS2404_CLK].gpio = pdata->gpio_clk; 53 ds2404_gpio[DS2404_DQ].gpio = pdata->gpio_dq; 54 55 for (i = 0; i < ARRAY_SIZE(ds2404_gpio); i++) { 56 err = gpio_request(ds2404_gpio[i].gpio, ds2404_gpio[i].name); 57 if (err) { 58 dev_err(&pdev->dev, "error mapping gpio %s: %d\n", 59 ds2404_gpio[i].name, err); 60 goto err_request; 61 } 62 if (i != DS2404_DQ) 63 gpio_direction_output(ds2404_gpio[i].gpio, 1); 64 } 65 66 chip->gpio = ds2404_gpio; 67 return 0; 68 69 err_request: 70 while (--i >= 0) 71 gpio_free(ds2404_gpio[i].gpio); 72 return err; 73 } 74 75 static void ds2404_gpio_unmap(void *data) 76 { 77 int i; 78 79 for (i = 0; i < ARRAY_SIZE(ds2404_gpio); i++) 80 gpio_free(ds2404_gpio[i].gpio); 81 } 82 83 static void ds2404_reset(struct device *dev) 84 { 85 gpio_set_value(ds2404_gpio[DS2404_RST].gpio, 0); 86 udelay(1000); 87 gpio_set_value(ds2404_gpio[DS2404_RST].gpio, 1); 88 gpio_set_value(ds2404_gpio[DS2404_CLK].gpio, 0); 89 gpio_direction_output(ds2404_gpio[DS2404_DQ].gpio, 0); 90 udelay(10); 91 } 92 93 static void ds2404_write_byte(struct device *dev, u8 byte) 94 { 95 int i; 96 97 gpio_direction_output(ds2404_gpio[DS2404_DQ].gpio, 1); 98 for (i = 0; i < 8; i++) { 99 gpio_set_value(ds2404_gpio[DS2404_DQ].gpio, byte & (1 << i)); 100 udelay(10); 101 gpio_set_value(ds2404_gpio[DS2404_CLK].gpio, 1); 102 udelay(10); 103 gpio_set_value(ds2404_gpio[DS2404_CLK].gpio, 0); 104 udelay(10); 105 } 106 } 107 108 static u8 ds2404_read_byte(struct device *dev) 109 { 110 int i; 111 u8 ret = 0; 112 113 gpio_direction_input(ds2404_gpio[DS2404_DQ].gpio); 114 115 for (i = 0; i < 8; i++) { 116 gpio_set_value(ds2404_gpio[DS2404_CLK].gpio, 0); 117 udelay(10); 118 if (gpio_get_value(ds2404_gpio[DS2404_DQ].gpio)) 119 ret |= 1 << i; 120 gpio_set_value(ds2404_gpio[DS2404_CLK].gpio, 1); 121 udelay(10); 122 } 123 return ret; 124 } 125 126 static void ds2404_read_memory(struct device *dev, u16 offset, 127 int length, u8 *out) 128 { 129 ds2404_reset(dev); 130 ds2404_write_byte(dev, DS2404_READ_MEMORY_CMD); 131 ds2404_write_byte(dev, offset & 0xff); 132 ds2404_write_byte(dev, (offset >> 8) & 0xff); 133 while (length--) 134 *out++ = ds2404_read_byte(dev); 135 } 136 137 static void ds2404_write_memory(struct device *dev, u16 offset, 138 int length, u8 *out) 139 { 140 int i; 141 u8 ta01, ta02, es; 142 143 ds2404_reset(dev); 144 ds2404_write_byte(dev, DS2404_WRITE_SCRATCHPAD_CMD); 145 ds2404_write_byte(dev, offset & 0xff); 146 ds2404_write_byte(dev, (offset >> 8) & 0xff); 147 148 for (i = 0; i < length; i++) 149 ds2404_write_byte(dev, out[i]); 150 151 ds2404_reset(dev); 152 ds2404_write_byte(dev, DS2404_READ_SCRATCHPAD_CMD); 153 154 ta01 = ds2404_read_byte(dev); 155 ta02 = ds2404_read_byte(dev); 156 es = ds2404_read_byte(dev); 157 158 for (i = 0; i < length; i++) { 159 if (out[i] != ds2404_read_byte(dev)) { 160 dev_err(dev, "read invalid data\n"); 161 return; 162 } 163 } 164 165 ds2404_reset(dev); 166 ds2404_write_byte(dev, DS2404_COPY_SCRATCHPAD_CMD); 167 ds2404_write_byte(dev, ta01); 168 ds2404_write_byte(dev, ta02); 169 ds2404_write_byte(dev, es); 170 171 gpio_direction_input(ds2404_gpio[DS2404_DQ].gpio); 172 while (gpio_get_value(ds2404_gpio[DS2404_DQ].gpio)) 173 ; 174 } 175 176 static void ds2404_enable_osc(struct device *dev) 177 { 178 u8 in[1] = { 0x10 }; /* enable oscillator */ 179 ds2404_write_memory(dev, 0x201, 1, in); 180 } 181 182 static int ds2404_read_time(struct device *dev, struct rtc_time *dt) 183 { 184 unsigned long time = 0; 185 __le32 hw_time = 0; 186 187 ds2404_read_memory(dev, 0x203, 4, (u8 *)&hw_time); 188 time = le32_to_cpu(hw_time); 189 190 rtc_time64_to_tm(time, dt); 191 return 0; 192 } 193 194 static int ds2404_set_time(struct device *dev, struct rtc_time *dt) 195 { 196 u32 time = cpu_to_le32(rtc_tm_to_time64(dt)); 197 ds2404_write_memory(dev, 0x203, 4, (u8 *)&time); 198 return 0; 199 } 200 201 static const struct rtc_class_ops ds2404_rtc_ops = { 202 .read_time = ds2404_read_time, 203 .set_time = ds2404_set_time, 204 }; 205 206 static int rtc_probe(struct platform_device *pdev) 207 { 208 struct ds2404_platform_data *pdata = dev_get_platdata(&pdev->dev); 209 struct ds2404 *chip; 210 int retval = -EBUSY; 211 212 chip = devm_kzalloc(&pdev->dev, sizeof(struct ds2404), GFP_KERNEL); 213 if (!chip) 214 return -ENOMEM; 215 216 chip->rtc = devm_rtc_allocate_device(&pdev->dev); 217 if (IS_ERR(chip->rtc)) 218 return PTR_ERR(chip->rtc); 219 220 retval = ds2404_gpio_map(chip, pdev, pdata); 221 if (retval) 222 return retval; 223 224 retval = devm_add_action_or_reset(&pdev->dev, ds2404_gpio_unmap, chip); 225 if (retval) 226 return retval; 227 228 dev_info(&pdev->dev, "using GPIOs RST:%d, CLK:%d, DQ:%d\n", 229 chip->gpio[DS2404_RST].gpio, chip->gpio[DS2404_CLK].gpio, 230 chip->gpio[DS2404_DQ].gpio); 231 232 platform_set_drvdata(pdev, chip); 233 234 chip->rtc->ops = &ds2404_rtc_ops; 235 chip->rtc->range_max = U32_MAX; 236 237 retval = devm_rtc_register_device(chip->rtc); 238 if (retval) 239 return retval; 240 241 ds2404_enable_osc(&pdev->dev); 242 return 0; 243 } 244 245 static struct platform_driver rtc_device_driver = { 246 .probe = rtc_probe, 247 .driver = { 248 .name = "ds2404", 249 }, 250 }; 251 module_platform_driver(rtc_device_driver); 252 253 MODULE_DESCRIPTION("DS2404 RTC"); 254 MODULE_AUTHOR("Sven Schnelle"); 255 MODULE_LICENSE("GPL"); 256 MODULE_ALIAS("platform:ds2404"); 257