318 строки
6.4 KiB
C
318 строки
6.4 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
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/*
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* drivers/rtc/rtc-pcf8583.c
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*
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* Copyright (C) 2000 Russell King
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* Copyright (C) 2008 Wolfram Sang & Juergen Beisert, Pengutronix
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*
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* Driver for PCF8583 RTC & RAM chip
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*
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* Converted to the generic RTC susbsystem by G. Liakhovetski (2006)
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*/
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#include <linux/module.h>
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#include <linux/i2c.h>
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#include <linux/slab.h>
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#include <linux/rtc.h>
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#include <linux/init.h>
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#include <linux/err.h>
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#include <linux/errno.h>
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#include <linux/bcd.h>
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struct rtc_mem {
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unsigned int loc;
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unsigned int nr;
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unsigned char *data;
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};
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struct pcf8583 {
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struct rtc_device *rtc;
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unsigned char ctrl;
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};
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#define CTRL_STOP 0x80
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#define CTRL_HOLD 0x40
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#define CTRL_32KHZ 0x00
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#define CTRL_MASK 0x08
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#define CTRL_ALARMEN 0x04
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#define CTRL_ALARM 0x02
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#define CTRL_TIMER 0x01
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static struct i2c_driver pcf8583_driver;
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#define get_ctrl(x) ((struct pcf8583 *)i2c_get_clientdata(x))->ctrl
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#define set_ctrl(x, v) get_ctrl(x) = v
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#define CMOS_YEAR (64 + 128)
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#define CMOS_CHECKSUM (63)
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static int pcf8583_get_datetime(struct i2c_client *client, struct rtc_time *dt)
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{
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unsigned char buf[8], addr[1] = { 1 };
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struct i2c_msg msgs[2] = {
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{
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.addr = client->addr,
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.flags = 0,
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.len = 1,
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.buf = addr,
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}, {
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.addr = client->addr,
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.flags = I2C_M_RD,
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.len = 6,
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.buf = buf,
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}
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};
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int ret;
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memset(buf, 0, sizeof(buf));
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ret = i2c_transfer(client->adapter, msgs, 2);
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if (ret == 2) {
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dt->tm_year = buf[4] >> 6;
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dt->tm_wday = buf[5] >> 5;
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buf[4] &= 0x3f;
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buf[5] &= 0x1f;
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dt->tm_sec = bcd2bin(buf[1]);
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dt->tm_min = bcd2bin(buf[2]);
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dt->tm_hour = bcd2bin(buf[3]);
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dt->tm_mday = bcd2bin(buf[4]);
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dt->tm_mon = bcd2bin(buf[5]) - 1;
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}
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return ret == 2 ? 0 : -EIO;
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}
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static int pcf8583_set_datetime(struct i2c_client *client, struct rtc_time *dt, int datetoo)
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{
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unsigned char buf[8];
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int ret, len = 6;
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buf[0] = 0;
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buf[1] = get_ctrl(client) | 0x80;
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buf[2] = 0;
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buf[3] = bin2bcd(dt->tm_sec);
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buf[4] = bin2bcd(dt->tm_min);
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buf[5] = bin2bcd(dt->tm_hour);
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if (datetoo) {
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len = 8;
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buf[6] = bin2bcd(dt->tm_mday) | (dt->tm_year << 6);
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buf[7] = bin2bcd(dt->tm_mon + 1) | (dt->tm_wday << 5);
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}
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ret = i2c_master_send(client, (char *)buf, len);
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if (ret != len)
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return -EIO;
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buf[1] = get_ctrl(client);
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ret = i2c_master_send(client, (char *)buf, 2);
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return ret == 2 ? 0 : -EIO;
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}
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static int pcf8583_get_ctrl(struct i2c_client *client, unsigned char *ctrl)
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{
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*ctrl = get_ctrl(client);
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return 0;
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}
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static int pcf8583_set_ctrl(struct i2c_client *client, unsigned char *ctrl)
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{
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unsigned char buf[2];
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buf[0] = 0;
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buf[1] = *ctrl;
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set_ctrl(client, *ctrl);
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return i2c_master_send(client, (char *)buf, 2);
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}
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static int pcf8583_read_mem(struct i2c_client *client, struct rtc_mem *mem)
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{
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unsigned char addr[1];
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struct i2c_msg msgs[2] = {
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{
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.addr = client->addr,
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.flags = 0,
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.len = 1,
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.buf = addr,
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}, {
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.addr = client->addr,
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.flags = I2C_M_RD,
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.len = mem->nr,
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.buf = mem->data,
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}
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};
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if (mem->loc < 8)
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return -EINVAL;
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addr[0] = mem->loc;
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return i2c_transfer(client->adapter, msgs, 2) == 2 ? 0 : -EIO;
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}
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static int pcf8583_write_mem(struct i2c_client *client, struct rtc_mem *mem)
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{
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unsigned char buf[9];
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int ret;
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if (mem->loc < 8 || mem->nr > 8)
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return -EINVAL;
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buf[0] = mem->loc;
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memcpy(buf + 1, mem->data, mem->nr);
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ret = i2c_master_send(client, buf, mem->nr + 1);
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return ret == mem->nr + 1 ? 0 : -EIO;
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}
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static int pcf8583_rtc_read_time(struct device *dev, struct rtc_time *tm)
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{
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struct i2c_client *client = to_i2c_client(dev);
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unsigned char ctrl, year[2];
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struct rtc_mem mem = {
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.loc = CMOS_YEAR,
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.nr = sizeof(year),
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.data = year
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};
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int real_year, year_offset, err;
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/*
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* Ensure that the RTC is running.
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*/
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pcf8583_get_ctrl(client, &ctrl);
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if (ctrl & (CTRL_STOP | CTRL_HOLD)) {
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unsigned char new_ctrl = ctrl & ~(CTRL_STOP | CTRL_HOLD);
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dev_warn(dev, "resetting control %02x -> %02x\n",
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ctrl, new_ctrl);
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err = pcf8583_set_ctrl(client, &new_ctrl);
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if (err < 0)
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return err;
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}
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if (pcf8583_get_datetime(client, tm) ||
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pcf8583_read_mem(client, &mem))
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return -EIO;
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real_year = year[0];
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/*
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* The RTC year holds the LSB two bits of the current
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* year, which should reflect the LSB two bits of the
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* CMOS copy of the year. Any difference indicates
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* that we have to correct the CMOS version.
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*/
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year_offset = tm->tm_year - (real_year & 3);
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if (year_offset < 0)
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/*
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* RTC year wrapped. Adjust it appropriately.
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*/
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year_offset += 4;
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tm->tm_year = (real_year + year_offset + year[1] * 100) - 1900;
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return 0;
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}
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static int pcf8583_rtc_set_time(struct device *dev, struct rtc_time *tm)
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{
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struct i2c_client *client = to_i2c_client(dev);
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unsigned char year[2], chk;
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struct rtc_mem cmos_year = {
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.loc = CMOS_YEAR,
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.nr = sizeof(year),
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.data = year
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};
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struct rtc_mem cmos_check = {
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.loc = CMOS_CHECKSUM,
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.nr = 1,
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.data = &chk
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};
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unsigned int proper_year = tm->tm_year + 1900;
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int ret;
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/*
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* The RTC's own 2-bit year must reflect the least
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* significant two bits of the CMOS year.
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*/
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ret = pcf8583_set_datetime(client, tm, 1);
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if (ret)
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return ret;
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ret = pcf8583_read_mem(client, &cmos_check);
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if (ret)
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return ret;
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ret = pcf8583_read_mem(client, &cmos_year);
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if (ret)
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return ret;
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chk -= year[1] + year[0];
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year[1] = proper_year / 100;
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year[0] = proper_year % 100;
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chk += year[1] + year[0];
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ret = pcf8583_write_mem(client, &cmos_year);
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if (ret)
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return ret;
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ret = pcf8583_write_mem(client, &cmos_check);
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return ret;
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}
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static const struct rtc_class_ops pcf8583_rtc_ops = {
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.read_time = pcf8583_rtc_read_time,
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.set_time = pcf8583_rtc_set_time,
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};
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static int pcf8583_probe(struct i2c_client *client)
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{
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struct pcf8583 *pcf8583;
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if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
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return -ENODEV;
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pcf8583 = devm_kzalloc(&client->dev, sizeof(struct pcf8583),
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GFP_KERNEL);
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if (!pcf8583)
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return -ENOMEM;
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i2c_set_clientdata(client, pcf8583);
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pcf8583->rtc = devm_rtc_device_register(&client->dev,
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pcf8583_driver.driver.name,
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&pcf8583_rtc_ops, THIS_MODULE);
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return PTR_ERR_OR_ZERO(pcf8583->rtc);
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}
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static const struct i2c_device_id pcf8583_id[] = {
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{ "pcf8583", 0 },
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{ }
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};
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MODULE_DEVICE_TABLE(i2c, pcf8583_id);
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static struct i2c_driver pcf8583_driver = {
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.driver = {
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.name = "pcf8583",
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},
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.probe_new = pcf8583_probe,
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.id_table = pcf8583_id,
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};
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module_i2c_driver(pcf8583_driver);
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MODULE_AUTHOR("Russell King");
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MODULE_DESCRIPTION("PCF8583 I2C RTC driver");
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MODULE_LICENSE("GPL");
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