[PATCH] drivers/acorn/char/pcf8583.[hc] vs. RTC subsystem

A port of the driver for the pcf8583 i2c rtc controller to the generic RTC
framework by Alessandro Zummo.  Based on
drivers/acorn/char/{pcf8583.[hc],i2c.c}.  Hopefully, acorn can be converted
too to use this driver in the future.

Signed-off-by: G. Liakhovetski <gl@dsa-ac.de>
Signed-off-by: Alessandro Zummo <a.zummo@towertech.it>
Cc: Russell King <rmk@arm.linux.org.uk>
Cc: Jean Delvare <khali@linux-fr.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 394 insertions, 0 deletions

diff --git a/drivers/rtc/rtc-pcf8583.c b/drivers/rtc/rtc-pcf8583.c
new file mode 100644
index 000000000000..b235a30cb661
--- /dev/null
+++ b/drivers/rtc/rtc-pcf8583.c
@@ -0,0 +1,394 @@
+/*
+ *  drivers/rtc/rtc-pcf8583.c
+ *
+ *  Copyright (C) 2000 Russell King
+ *
+ * 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/string.h>
+#include <linux/mc146818rtc.h>
+#include <linux/init.h>
+#include <linux/errno.h>
+#include <linux/bcd.h>
+
+struct rtc_mem {
+        unsigned int    loc;
+        unsigned int    nr;
+        unsigned char   *data;
+};
+
+struct pcf8583 {
+        struct i2c_client client;
+        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 unsigned short normal_i2c[] = { I2C_CLIENT_END };
+
+/* Module parameters */
+I2C_CLIENT_INSMOD;
+
+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 = BCD_TO_BIN(buf[1]);
+                dt->tm_min = BCD_TO_BIN(buf[2]);
+                dt->tm_hour = BCD_TO_BIN(buf[3]);
+                dt->tm_mday = BCD_TO_BIN(buf[4]);
+                dt->tm_mon = BCD_TO_BIN(buf[5]);
+        }
+
+        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] = BIN_TO_BCD(dt->tm_sec);
+        buf[4] = BIN_TO_BCD(dt->tm_min);
+        buf[5] = BIN_TO_BCD(dt->tm_hour);
+
+        if (datetoo) {
+                len = 8;
+                buf[6] = BIN_TO_BCD(dt->tm_mday) | (dt->tm_year << 6);
+                buf[7] = BIN_TO_BCD(dt->tm_mon)  | (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 addr[1];
+        struct i2c_msg msgs[2] = {
+                {
+                        .addr = client->addr,
+                        .flags = 0,
+                        .len = 1,
+                        .buf = addr,
+                }, {
+                        .addr = client->addr,
+                        .flags = I2C_M_NOSTART,
+                        .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_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);
+
+                printk(KERN_WARNING "RTC: resetting control %02x -> %02x\n",
+                       ctrl, new_ctrl);
+
+                if ((err = pcf8583_set_ctrl(client, &new_ctrl)) < 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;
+
+        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 };
+        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] = tm->tm_year / 100;
+        year[0] = tm->tm_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 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_adapter *adap, int addr, int kind);
+
+static int pcf8583_attach(struct i2c_adapter *adap)
+{
+        return i2c_probe(adap, &addr_data, pcf8583_probe);
+}
+
+static int pcf8583_detach(struct i2c_client *client)
+{
+        int err;
+        struct pcf8583 *pcf = i2c_get_clientdata(client);
+        struct rtc_device *rtc = pcf->rtc;
+
+        if (rtc)
+                rtc_device_unregister(rtc);
+
+        if ((err = i2c_detach_client(client)))
+                return err;
+
+        kfree(pcf);
+        return 0;
+}
+
+static struct i2c_driver pcf8583_driver = {
+        .driver = {
+                .name   = "pcf8583",
+        },
+        .id             = I2C_DRIVERID_PCF8583,
+        .attach_adapter = pcf8583_attach,
+        .detach_client  = pcf8583_detach,
+};
+
+static int pcf8583_probe(struct i2c_adapter *adap, int addr, int kind)
+{
+        struct pcf8583 *pcf;
+        struct i2c_client *client;
+        struct rtc_device *rtc;
+        unsigned char buf[1], ad[1] = { 0 };
+        int err;
+        struct i2c_msg msgs[2] = {
+                {
+                        .addr = addr,
+                        .flags = 0,
+                        .len = 1,
+                        .buf = ad,
+                }, {
+                        .addr = addr,
+                        .flags = I2C_M_RD,
+                        .len = 1,
+                        .buf = buf,
+                }
+        };
+
+        pcf = kzalloc(sizeof(*pcf), GFP_KERNEL);
+        if (!pcf)
+                return -ENOMEM;
+
+        client = &pcf->client;
+
+        client->addr            = addr;
+        client->adapter = adap;
+        client->driver  = &pcf8583_driver;
+
+        strlcpy(client->name, pcf8583_driver.driver.name, I2C_NAME_SIZE);
+
+        if (i2c_transfer(client->adapter, msgs, 2) != 2) {
+                err = -EIO;
+                goto exit_kfree;
+        }
+
+        err = i2c_attach_client(client);
+
+        if (err)
+                goto exit_kfree;
+
+        rtc = rtc_device_register(pcf8583_driver.driver.name, &client->dev,
+                                  &pcf8583_rtc_ops, THIS_MODULE);
+
+        if (IS_ERR(rtc)) {
+                err = PTR_ERR(rtc);
+                goto exit_detach;
+        }
+
+        pcf->rtc = rtc;
+        i2c_set_clientdata(client, pcf);
+        set_ctrl(client, buf[0]);
+
+        return 0;
+
+exit_detach:
+        i2c_detach_client(client);
+
+exit_kfree:
+        kfree(pcf);
+
+        return err;
+}
+
+static __init int pcf8583_init(void)
+{
+        return i2c_add_driver(&pcf8583_driver);
+}
+
+static __exit void pcf8583_exit(void)
+{
+        i2c_del_driver(&pcf8583_driver);
+}
+
+module_init(pcf8583_init);
+module_exit(pcf8583_exit);
+
+MODULE_AUTHOR("Russell King");
+MODULE_DESCRIPTION("PCF8583 I2C RTC driver");
+MODULE_LICENSE("GPL");