/* * drivers/rtc/rtc-pcf8583.c * * Copyright (C) 2000 Russell King * Copyright (C) 2008 Wolfram Sang & Juergen Beisert, Pengutronix * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License version 2 as * published by the Free Software Foundation. * * Driver for PCF8583 RTC & RAM chip * * Converted to the generic RTC susbsystem by G. Liakhovetski (2006) */ #include <linux/module.h> #include <linux/i2c.h> #include <linux/slab.h> #include <linux/rtc.h> #include <linux/init.h> #include <linux/err.h> #include <linux/errno.h> #include <linux/bcd.h> struct rtc_mem { unsigned int loc; unsigned int nr; unsigned char *data; }; struct pcf8583 { struct rtc_device *rtc; unsigned char ctrl; }; #define CTRL_STOP 0x80 #define CTRL_HOLD 0x40 #define CTRL_32KHZ 0x00 #define CTRL_MASK 0x08 #define CTRL_ALARMEN 0x04 #define CTRL_ALARM 0x02 #define CTRL_TIMER 0x01 static struct i2c_driver pcf8583_driver; #define get_ctrl(x) ((struct pcf8583 *)i2c_get_clientdata(x))->ctrl #define set_ctrl(x, v) get_ctrl(x) = v #define CMOS_YEAR (64 + 128) #define CMOS_CHECKSUM (63) static int pcf8583_get_datetime(struct i2c_client *client, struct rtc_time *dt) { unsigned char buf[8], addr[1] = { 1 }; struct i2c_msg msgs[2] = { { .addr = client->addr, .flags = 0, .len = 1, .buf = addr, }, { .addr = client->addr, .flags = I2C_M_RD, .len = 6, .buf = buf, } }; int ret; memset(buf, 0, sizeof(buf)); ret = i2c_transfer(client->adapter, msgs, 2); if (ret == 2) { dt->tm_year = buf[4] >> 6; dt->tm_wday = buf[5] >> 5; buf[4] &= 0x3f; buf[5] &= 0x1f; dt->tm_sec = bcd2bin(buf[1]); dt->tm_min = bcd2bin(buf[2]); dt->tm_hour = bcd2bin(buf[3]); dt->tm_mday = bcd2bin(buf[4]); dt->tm_mon = bcd2bin(buf[5]) - 1; } return ret == 2 ? 0 : -EIO; } static int pcf8583_set_datetime(struct i2c_client *client, struct rtc_time *dt, int datetoo) { unsigned char buf[8]; int ret, len = 6; buf[0] = 0; buf[1] = get_ctrl(client) | 0x80; buf[2] = 0; buf[3] = bin2bcd(dt->tm_sec); buf[4] = bin2bcd(dt->tm_min); buf[5] = bin2bcd(dt->tm_hour); if (datetoo) { len = 8; buf[6] = bin2bcd(dt->tm_mday) | (dt->tm_year << 6); buf[7] = bin2bcd(dt->tm_mon + 1) | (dt->tm_wday << 5); } ret = i2c_master_send(client, (char *)buf, len); if (ret != len) return -EIO; buf[1] = get_ctrl(client); ret = i2c_master_send(client, (char *)buf, 2); return ret == 2 ? 0 : -EIO; } static int pcf8583_get_ctrl(struct i2c_client *client, unsigned char *ctrl) { *ctrl = get_ctrl(client); return 0; } static int pcf8583_set_ctrl(struct i2c_client *client, unsigned char *ctrl) { unsigned char buf[2]; buf[0] = 0; buf[1] = *ctrl; set_ctrl(client, *ctrl); return i2c_master_send(client, (char *)buf, 2); } static int pcf8583_read_mem(struct i2c_client *client, struct rtc_mem *mem) { unsigned char addr[1]; struct i2c_msg msgs[2] = { { .addr = client->addr, .flags = 0, .len = 1, .buf = addr, }, { .addr = client->addr, .flags = I2C_M_RD, .len = mem->nr, .buf = mem->data, } }; if (mem->loc < 8) return -EINVAL; addr[0] = mem->loc; return i2c_transfer(client->adapter, msgs, 2) == 2 ? 0 : -EIO; } static int pcf8583_write_mem(struct i2c_client *client, struct rtc_mem *mem) { unsigned char buf[9]; int ret; if (mem->loc < 8 || mem->nr > 8) return -EINVAL; buf[0] = mem->loc; memcpy(buf + 1, mem->data, mem->nr); ret = i2c_master_send(client, buf, mem->nr + 1); return ret == mem->nr + 1 ? 0 : -EIO; } static int pcf8583_rtc_read_time(struct device *dev, struct rtc_time *tm) { struct i2c_client *client = to_i2c_client(dev); unsigned char ctrl, year[2]; struct rtc_mem mem = { CMOS_YEAR, sizeof(year), year }; int real_year, year_offset, err; /* * Ensure that the RTC is running. */ pcf8583_get_ctrl(client, &ctrl); if (ctrl & (CTRL_STOP | CTRL_HOLD)) { unsigned char new_ctrl = ctrl & ~(CTRL_STOP | CTRL_HOLD); dev_warn(dev, "resetting control %02x -> %02x\n", ctrl, new_ctrl); err = pcf8583_set_ctrl(client, &new_ctrl); if (err < 0) return err; } if (pcf8583_get_datetime(client, tm) || pcf8583_read_mem(client, &mem)) return -EIO; real_year = year[0]; /* * The RTC year holds the LSB two bits of the current * year, which should reflect the LSB two bits of the * CMOS copy of the year. Any difference indicates * that we have to correct the CMOS version. */ year_offset = tm->tm_year - (real_year & 3); if (year_offset < 0) /* * RTC year wrapped. Adjust it appropriately. */ year_offset += 4; tm->tm_year = (real_year + year_offset + year[1] * 100) - 1900; return 0; } static int pcf8583_rtc_set_time(struct device *dev, struct rtc_time *tm) { struct i2c_client *client = to_i2c_client(dev); unsigned char year[2], chk; struct rtc_mem cmos_year = { CMOS_YEAR, sizeof(year), year }; struct rtc_mem cmos_check = { CMOS_CHECKSUM, 1, &chk }; unsigned int proper_year = tm->tm_year + 1900; int ret; /* * The RTC's own 2-bit year must reflect the least * significant two bits of the CMOS year. */ ret = pcf8583_set_datetime(client, tm, 1); if (ret) return ret; ret = pcf8583_read_mem(client, &cmos_check); if (ret) return ret; ret = pcf8583_read_mem(client, &cmos_year); if (ret) return ret; chk -= year[1] + year[0]; year[1] = proper_year / 100; year[0] = proper_year % 100; chk += year[1] + year[0]; ret = pcf8583_write_mem(client, &cmos_year); if (ret) return ret; ret = pcf8583_write_mem(client, &cmos_check); return ret; } static const struct rtc_class_ops pcf8583_rtc_ops = { .read_time = pcf8583_rtc_read_time, .set_time = pcf8583_rtc_set_time, }; static int pcf8583_probe(struct i2c_client *client, const struct i2c_device_id *id) { struct pcf8583 *pcf8583; if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C)) return -ENODEV; pcf8583 = devm_kzalloc(&client->dev, sizeof(struct pcf8583), GFP_KERNEL); if (!pcf8583) return -ENOMEM; i2c_set_clientdata(client, pcf8583); pcf8583->rtc = devm_rtc_device_register(&client->dev, pcf8583_driver.driver.name, &pcf8583_rtc_ops, THIS_MODULE); return PTR_ERR_OR_ZERO(pcf8583->rtc); } static const struct i2c_device_id pcf8583_id[] = { { "pcf8583", 0 }, { } }; MODULE_DEVICE_TABLE(i2c, pcf8583_id); static struct i2c_driver pcf8583_driver = { .driver = { .name = "pcf8583", .owner = THIS_MODULE, }, .probe = pcf8583_probe, .id_table = pcf8583_id, }; module_i2c_driver(pcf8583_driver); MODULE_AUTHOR("Russell King"); MODULE_DESCRIPTION("PCF8583 I2C RTC driver"); MODULE_LICENSE("GPL");