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1// SPDX-License-Identifier: GPL-2.0-only2/*3 * drivers/rtc/rtc-pcf8583.c4 *5 * Copyright (C) 2000 Russell King6 * Copyright (C) 2008 Wolfram Sang & Juergen Beisert, Pengutronix7 *8 * Driver for PCF8583 RTC & RAM chip9 *10 * Converted to the generic RTC susbsystem by G. Liakhovetski (2006)11 */12#include <linux/module.h>13#include <linux/i2c.h>14#include <linux/slab.h>15#include <linux/rtc.h>16#include <linux/init.h>17#include <linux/err.h>18#include <linux/errno.h>19#include <linux/bcd.h>20 21struct rtc_mem {22 unsigned int loc;23 unsigned int nr;24 unsigned char *data;25};26 27struct pcf8583 {28 struct rtc_device *rtc;29 unsigned char ctrl;30};31 32#define CTRL_STOP 0x8033#define CTRL_HOLD 0x4034#define CTRL_32KHZ 0x0035#define CTRL_MASK 0x0836#define CTRL_ALARMEN 0x0437#define CTRL_ALARM 0x0238#define CTRL_TIMER 0x0139 40 41static struct i2c_driver pcf8583_driver;42 43#define get_ctrl(x) ((struct pcf8583 *)i2c_get_clientdata(x))->ctrl44#define set_ctrl(x, v) get_ctrl(x) = v45 46#define CMOS_YEAR (64 + 128)47#define CMOS_CHECKSUM (63)48 49static int pcf8583_get_datetime(struct i2c_client *client, struct rtc_time *dt)50{51 unsigned char buf[8], addr[1] = { 1 };52 struct i2c_msg msgs[2] = {53 {54 .addr = client->addr,55 .flags = 0,56 .len = 1,57 .buf = addr,58 }, {59 .addr = client->addr,60 .flags = I2C_M_RD,61 .len = 6,62 .buf = buf,63 }64 };65 int ret;66 67 memset(buf, 0, sizeof(buf));68 69 ret = i2c_transfer(client->adapter, msgs, 2);70 if (ret == 2) {71 dt->tm_year = buf[4] >> 6;72 dt->tm_wday = buf[5] >> 5;73 74 buf[4] &= 0x3f;75 buf[5] &= 0x1f;76 77 dt->tm_sec = bcd2bin(buf[1]);78 dt->tm_min = bcd2bin(buf[2]);79 dt->tm_hour = bcd2bin(buf[3]);80 dt->tm_mday = bcd2bin(buf[4]);81 dt->tm_mon = bcd2bin(buf[5]) - 1;82 }83 84 return ret == 2 ? 0 : -EIO;85}86 87static int pcf8583_set_datetime(struct i2c_client *client, struct rtc_time *dt, int datetoo)88{89 unsigned char buf[8];90 int ret, len = 6;91 92 buf[0] = 0;93 buf[1] = get_ctrl(client) | 0x80;94 buf[2] = 0;95 buf[3] = bin2bcd(dt->tm_sec);96 buf[4] = bin2bcd(dt->tm_min);97 buf[5] = bin2bcd(dt->tm_hour);98 99 if (datetoo) {100 len = 8;101 buf[6] = bin2bcd(dt->tm_mday) | (dt->tm_year << 6);102 buf[7] = bin2bcd(dt->tm_mon + 1) | (dt->tm_wday << 5);103 }104 105 ret = i2c_master_send(client, (char *)buf, len);106 if (ret != len)107 return -EIO;108 109 buf[1] = get_ctrl(client);110 ret = i2c_master_send(client, (char *)buf, 2);111 112 return ret == 2 ? 0 : -EIO;113}114 115static int pcf8583_get_ctrl(struct i2c_client *client, unsigned char *ctrl)116{117 *ctrl = get_ctrl(client);118 return 0;119}120 121static int pcf8583_set_ctrl(struct i2c_client *client, unsigned char *ctrl)122{123 unsigned char buf[2];124 125 buf[0] = 0;126 buf[1] = *ctrl;127 set_ctrl(client, *ctrl);128 129 return i2c_master_send(client, (char *)buf, 2);130}131 132static int pcf8583_read_mem(struct i2c_client *client, struct rtc_mem *mem)133{134 unsigned char addr[1];135 struct i2c_msg msgs[2] = {136 {137 .addr = client->addr,138 .flags = 0,139 .len = 1,140 .buf = addr,141 }, {142 .addr = client->addr,143 .flags = I2C_M_RD,144 .len = mem->nr,145 .buf = mem->data,146 }147 };148 149 if (mem->loc < 8)150 return -EINVAL;151 152 addr[0] = mem->loc;153 154 return i2c_transfer(client->adapter, msgs, 2) == 2 ? 0 : -EIO;155}156 157static int pcf8583_write_mem(struct i2c_client *client, struct rtc_mem *mem)158{159 unsigned char buf[9];160 int ret;161 162 if (mem->loc < 8 || mem->nr > 8)163 return -EINVAL;164 165 buf[0] = mem->loc;166 memcpy(buf + 1, mem->data, mem->nr);167 168 ret = i2c_master_send(client, buf, mem->nr + 1);169 return ret == mem->nr + 1 ? 0 : -EIO;170}171 172static int pcf8583_rtc_read_time(struct device *dev, struct rtc_time *tm)173{174 struct i2c_client *client = to_i2c_client(dev);175 unsigned char ctrl, year[2];176 struct rtc_mem mem = {177 .loc = CMOS_YEAR,178 .nr = sizeof(year),179 .data = year180 };181 int real_year, year_offset, err;182 183 /*184 * Ensure that the RTC is running.185 */186 pcf8583_get_ctrl(client, &ctrl);187 if (ctrl & (CTRL_STOP | CTRL_HOLD)) {188 unsigned char new_ctrl = ctrl & ~(CTRL_STOP | CTRL_HOLD);189 190 dev_warn(dev, "resetting control %02x -> %02x\n",191 ctrl, new_ctrl);192 193 err = pcf8583_set_ctrl(client, &new_ctrl);194 if (err < 0)195 return err;196 }197 198 if (pcf8583_get_datetime(client, tm) ||199 pcf8583_read_mem(client, &mem))200 return -EIO;201 202 real_year = year[0];203 204 /*205 * The RTC year holds the LSB two bits of the current206 * year, which should reflect the LSB two bits of the207 * CMOS copy of the year. Any difference indicates208 * that we have to correct the CMOS version.209 */210 year_offset = tm->tm_year - (real_year & 3);211 if (year_offset < 0)212 /*213 * RTC year wrapped. Adjust it appropriately.214 */215 year_offset += 4;216 217 tm->tm_year = (real_year + year_offset + year[1] * 100) - 1900;218 219 return 0;220}221 222static int pcf8583_rtc_set_time(struct device *dev, struct rtc_time *tm)223{224 struct i2c_client *client = to_i2c_client(dev);225 unsigned char year[2], chk;226 struct rtc_mem cmos_year = {227 .loc = CMOS_YEAR,228 .nr = sizeof(year),229 .data = year230 };231 struct rtc_mem cmos_check = {232 .loc = CMOS_CHECKSUM,233 .nr = 1,234 .data = &chk235 };236 unsigned int proper_year = tm->tm_year + 1900;237 int ret;238 239 /*240 * The RTC's own 2-bit year must reflect the least241 * significant two bits of the CMOS year.242 */243 244 ret = pcf8583_set_datetime(client, tm, 1);245 if (ret)246 return ret;247 248 ret = pcf8583_read_mem(client, &cmos_check);249 if (ret)250 return ret;251 252 ret = pcf8583_read_mem(client, &cmos_year);253 if (ret)254 return ret;255 256 chk -= year[1] + year[0];257 258 year[1] = proper_year / 100;259 year[0] = proper_year % 100;260 261 chk += year[1] + year[0];262 263 ret = pcf8583_write_mem(client, &cmos_year);264 265 if (ret)266 return ret;267 268 ret = pcf8583_write_mem(client, &cmos_check);269 270 return ret;271}272 273static const struct rtc_class_ops pcf8583_rtc_ops = {274 .read_time = pcf8583_rtc_read_time,275 .set_time = pcf8583_rtc_set_time,276};277 278static int pcf8583_probe(struct i2c_client *client)279{280 struct pcf8583 *pcf8583;281 282 if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))283 return -ENODEV;284 285 pcf8583 = devm_kzalloc(&client->dev, sizeof(struct pcf8583),286 GFP_KERNEL);287 if (!pcf8583)288 return -ENOMEM;289 290 i2c_set_clientdata(client, pcf8583);291 292 pcf8583->rtc = devm_rtc_device_register(&client->dev,293 pcf8583_driver.driver.name,294 &pcf8583_rtc_ops, THIS_MODULE);295 296 return PTR_ERR_OR_ZERO(pcf8583->rtc);297}298 299static const struct i2c_device_id pcf8583_id[] = {300 { "pcf8583" },301 { }302};303MODULE_DEVICE_TABLE(i2c, pcf8583_id);304 305static struct i2c_driver pcf8583_driver = {306 .driver = {307 .name = "pcf8583",308 },309 .probe = pcf8583_probe,310 .id_table = pcf8583_id,311};312 313module_i2c_driver(pcf8583_driver);314 315MODULE_AUTHOR("Russell King");316MODULE_DESCRIPTION("PCF8583 I2C RTC driver");317MODULE_LICENSE("GPL");318