[PATCH] RTC subsystem: X1205 driver

A port of the existing x1205 driver under the new RTC subsystem.

It is actually under test within the NSLU2 project
(http://www.nslu2-linux.org) and it is working quite well.

It is the first driver under this new subsystem and should be used as a guide
to port other drivers.

Signed-off-by: Alessandro Zummo <a.zummo@towertech.it>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 619 insertions, 0 deletions

diff --git a/drivers/rtc/rtc-x1205.c b/drivers/rtc/rtc-x1205.c
new file mode 100644
index 000000000000..621d17afc0d9
--- /dev/null
+++ b/drivers/rtc/rtc-x1205.c
@@ -0,0 +1,619 @@
+/*
+ * An i2c driver for the Xicor/Intersil X1205 RTC
+ * Copyright 2004 Karen Spearel
+ * Copyright 2005 Alessandro Zummo
+ *
+ * please send all reports to:
+ *      Karen Spearel <kas111 at gmail dot com>
+ *      Alessandro Zummo <a.zummo@towertech.it>
+ *
+ * based on a lot of other RTC drivers.
+ *
+ * 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.
+ */
+
+#include <linux/i2c.h>
+#include <linux/bcd.h>
+#include <linux/rtc.h>
+#include <linux/delay.h>
+
+#define DRV_VERSION "1.0.6"
+
+/* Addresses to scan: none. This chip is located at
+ * 0x6f and uses a two bytes register addressing.
+ * Two bytes need to be written to read a single register,
+ * while most other chips just require one and take the second
+ * one as the data to be written. To prevent corrupting
+ * unknown chips, the user must explicitely set the probe parameter.
+ */
+
+static unsigned short normal_i2c[] = { I2C_CLIENT_END };
+
+/* Insmod parameters */
+I2C_CLIENT_INSMOD;
+
+/* offsets into CCR area */
+
+#define CCR_SEC                 0
+#define CCR_MIN                 1
+#define CCR_HOUR                2
+#define CCR_MDAY                3
+#define CCR_MONTH               4
+#define CCR_YEAR                5
+#define CCR_WDAY                6
+#define CCR_Y2K                 7
+
+#define X1205_REG_SR            0x3F    /* status register */
+#define X1205_REG_Y2K           0x37
+#define X1205_REG_DW            0x36
+#define X1205_REG_YR            0x35
+#define X1205_REG_MO            0x34
+#define X1205_REG_DT            0x33
+#define X1205_REG_HR            0x32
+#define X1205_REG_MN            0x31
+#define X1205_REG_SC            0x30
+#define X1205_REG_DTR           0x13
+#define X1205_REG_ATR           0x12
+#define X1205_REG_INT           0x11
+#define X1205_REG_0             0x10
+#define X1205_REG_Y2K1          0x0F
+#define X1205_REG_DWA1          0x0E
+#define X1205_REG_YRA1          0x0D
+#define X1205_REG_MOA1          0x0C
+#define X1205_REG_DTA1          0x0B
+#define X1205_REG_HRA1          0x0A
+#define X1205_REG_MNA1          0x09
+#define X1205_REG_SCA1          0x08
+#define X1205_REG_Y2K0          0x07
+#define X1205_REG_DWA0          0x06
+#define X1205_REG_YRA0          0x05
+#define X1205_REG_MOA0          0x04
+#define X1205_REG_DTA0          0x03
+#define X1205_REG_HRA0          0x02
+#define X1205_REG_MNA0          0x01
+#define X1205_REG_SCA0          0x00
+
+#define X1205_CCR_BASE          0x30    /* Base address of CCR */
+#define X1205_ALM0_BASE         0x00    /* Base address of ALARM0 */
+
+#define X1205_SR_RTCF           0x01    /* Clock failure */
+#define X1205_SR_WEL            0x02    /* Write Enable Latch */
+#define X1205_SR_RWEL           0x04    /* Register Write Enable */
+
+#define X1205_DTR_DTR0          0x01
+#define X1205_DTR_DTR1          0x02
+#define X1205_DTR_DTR2          0x04
+
+#define X1205_HR_MIL            0x80    /* Set in ccr.hour for 24 hr mode */
+
+/* Prototypes */
+static int x1205_attach(struct i2c_adapter *adapter);
+static int x1205_detach(struct i2c_client *client);
+static int x1205_probe(struct i2c_adapter *adapter, int address, int kind);
+
+static struct i2c_driver x1205_driver = {
+        .driver         = {
+                .name   = "x1205",
+        },
+        .id             = I2C_DRIVERID_X1205,
+        .attach_adapter = &x1205_attach,
+        .detach_client  = &x1205_detach,
+};
+
+/*
+ * In the routines that deal directly with the x1205 hardware, we use
+ * rtc_time -- month 0-11, hour 0-23, yr = calendar year-epoch
+ * Epoch is initialized as 2000. Time is set to UTC.
+ */
+static int x1205_get_datetime(struct i2c_client *client, struct rtc_time *tm,
+                                unsigned char reg_base)
+{
+        unsigned char dt_addr[2] = { 0, reg_base };
+
+        unsigned char buf[8];
+
+        struct i2c_msg msgs[] = {
+                { client->addr, 0, 2, dt_addr },        /* setup read ptr */
+                { client->addr, I2C_M_RD, 8, buf },     /* read date */
+        };
+
+        /* read date registers */
+        if ((i2c_transfer(client->adapter, &msgs[0], 2)) != 2) {
+                dev_err(&client->dev, "%s: read error\n", __FUNCTION__);
+                return -EIO;
+        }
+
+        dev_dbg(&client->dev,
+                "%s: raw read data - sec=%02x, min=%02x, hr=%02x, "
+                "mday=%02x, mon=%02x, year=%02x, wday=%02x, y2k=%02x\n",
+                __FUNCTION__,
+                buf[0], buf[1], buf[2], buf[3],
+                buf[4], buf[5], buf[6], buf[7]);
+
+        tm->tm_sec = BCD2BIN(buf[CCR_SEC]);
+        tm->tm_min = BCD2BIN(buf[CCR_MIN]);
+        tm->tm_hour = BCD2BIN(buf[CCR_HOUR] & 0x3F); /* hr is 0-23 */
+        tm->tm_mday = BCD2BIN(buf[CCR_MDAY]);
+        tm->tm_mon = BCD2BIN(buf[CCR_MONTH]) - 1; /* mon is 0-11 */
+        tm->tm_year = BCD2BIN(buf[CCR_YEAR])
+                        + (BCD2BIN(buf[CCR_Y2K]) * 100) - 1900;
+        tm->tm_wday = buf[CCR_WDAY];
+
+        dev_dbg(&client->dev, "%s: tm is secs=%d, mins=%d, hours=%d, "
+                "mday=%d, mon=%d, year=%d, wday=%d\n",
+                __FUNCTION__,
+                tm->tm_sec, tm->tm_min, tm->tm_hour,
+                tm->tm_mday, tm->tm_mon, tm->tm_year, tm->tm_wday);
+
+        return 0;
+}
+
+static int x1205_get_status(struct i2c_client *client, unsigned char *sr)
+{
+        static unsigned char sr_addr[2] = { 0, X1205_REG_SR };
+
+        struct i2c_msg msgs[] = {
+                { client->addr, 0, 2, sr_addr },        /* setup read ptr */
+                { client->addr, I2C_M_RD, 1, sr },      /* read status */
+        };
+
+        /* read status register */
+        if ((i2c_transfer(client->adapter, &msgs[0], 2)) != 2) {
+                dev_err(&client->dev, "%s: read error\n", __FUNCTION__);
+                return -EIO;
+        }
+
+        return 0;
+}
+
+static int x1205_set_datetime(struct i2c_client *client, struct rtc_time *tm,
+                                int datetoo, u8 reg_base)
+{
+        int i, xfer;
+        unsigned char buf[8];
+
+        static const unsigned char wel[3] = { 0, X1205_REG_SR,
+                                                X1205_SR_WEL };
+
+        static const unsigned char rwel[3] = { 0, X1205_REG_SR,
+                                                X1205_SR_WEL | X1205_SR_RWEL };
+
+        static const unsigned char diswe[3] = { 0, X1205_REG_SR, 0 };
+
+        dev_dbg(&client->dev,
+                "%s: secs=%d, mins=%d, hours=%d\n",
+                __FUNCTION__,
+                tm->tm_sec, tm->tm_min, tm->tm_hour);
+
+        buf[CCR_SEC] = BIN2BCD(tm->tm_sec);
+        buf[CCR_MIN] = BIN2BCD(tm->tm_min);
+
+        /* set hour and 24hr bit */
+        buf[CCR_HOUR] = BIN2BCD(tm->tm_hour) | X1205_HR_MIL;
+
+        /* should we also set the date? */
+        if (datetoo) {
+                dev_dbg(&client->dev,
+                        "%s: mday=%d, mon=%d, year=%d, wday=%d\n",
+                        __FUNCTION__,
+                        tm->tm_mday, tm->tm_mon, tm->tm_year, tm->tm_wday);
+
+                buf[CCR_MDAY] = BIN2BCD(tm->tm_mday);
+
+                /* month, 1 - 12 */
+                buf[CCR_MONTH] = BIN2BCD(tm->tm_mon + 1);
+
+                /* year, since the rtc epoch*/
+                buf[CCR_YEAR] = BIN2BCD(tm->tm_year % 100);
+                buf[CCR_WDAY] = tm->tm_wday & 0x07;
+                buf[CCR_Y2K] = BIN2BCD(tm->tm_year / 100);
+        }
+
+        /* this sequence is required to unlock the chip */
+        if ((xfer = i2c_master_send(client, wel, 3)) != 3) {
+                dev_err(&client->dev, "%s: wel - %d\n", __FUNCTION__, xfer);
+                return -EIO;
+        }
+
+        if ((xfer = i2c_master_send(client, rwel, 3)) != 3) {
+                dev_err(&client->dev, "%s: rwel - %d\n", __FUNCTION__, xfer);
+                return -EIO;
+        }
+
+        /* write register's data */
+        for (i = 0; i < (datetoo ? 8 : 3); i++) {
+                unsigned char rdata[3] = { 0, reg_base + i, buf[i] };
+
+                xfer = i2c_master_send(client, rdata, 3);
+                if (xfer != 3) {
+                        dev_err(&client->dev,
+                                "%s: xfer=%d addr=%02x, data=%02x\n",
+                                __FUNCTION__,
+                                 xfer, rdata[1], rdata[2]);
+                        return -EIO;
+                }
+        };
+
+        /* disable further writes */
+        if ((xfer = i2c_master_send(client, diswe, 3)) != 3) {
+                dev_err(&client->dev, "%s: diswe - %d\n", __FUNCTION__, xfer);
+                return -EIO;
+        }
+
+        return 0;
+}
+
+static int x1205_fix_osc(struct i2c_client *client)
+{
+        int err;
+        struct rtc_time tm;
+
+        tm.tm_hour = tm.tm_min = tm.tm_sec = 0;
+
+        if ((err = x1205_set_datetime(client, &tm, 0, X1205_CCR_BASE)) < 0)
+                dev_err(&client->dev,
+                        "unable to restart the oscillator\n");
+
+        return err;
+}
+
+static int x1205_get_dtrim(struct i2c_client *client, int *trim)
+{
+        unsigned char dtr;
+        static unsigned char dtr_addr[2] = { 0, X1205_REG_DTR };
+
+        struct i2c_msg msgs[] = {
+                { client->addr, 0, 2, dtr_addr },       /* setup read ptr */
+                { client->addr, I2C_M_RD, 1, &dtr },    /* read dtr */
+        };
+
+        /* read dtr register */
+        if ((i2c_transfer(client->adapter, &msgs[0], 2)) != 2) {
+                dev_err(&client->dev, "%s: read error\n", __FUNCTION__);
+                return -EIO;
+        }
+
+        dev_dbg(&client->dev, "%s: raw dtr=%x\n", __FUNCTION__, dtr);
+
+        *trim = 0;
+
+        if (dtr & X1205_DTR_DTR0)
+                *trim += 20;
+
+        if (dtr & X1205_DTR_DTR1)
+                *trim += 10;
+
+        if (dtr & X1205_DTR_DTR2)
+                *trim = -*trim;
+
+        return 0;
+}
+
+static int x1205_get_atrim(struct i2c_client *client, int *trim)
+{
+        s8 atr;
+        static unsigned char atr_addr[2] = { 0, X1205_REG_ATR };
+
+        struct i2c_msg msgs[] = {
+                { client->addr, 0, 2, atr_addr },       /* setup read ptr */
+                { client->addr, I2C_M_RD, 1, &atr },    /* read atr */
+        };
+
+        /* read atr register */
+        if ((i2c_transfer(client->adapter, &msgs[0], 2)) != 2) {
+                dev_err(&client->dev, "%s: read error\n", __FUNCTION__);
+                return -EIO;
+        }
+
+        dev_dbg(&client->dev, "%s: raw atr=%x\n", __FUNCTION__, atr);
+
+        /* atr is a two's complement value on 6 bits,
+         * perform sign extension. The formula is
+         * Catr = (atr * 0.25pF) + 11.00pF.
+         */
+        if (atr & 0x20)
+                atr |= 0xC0;
+
+        dev_dbg(&client->dev, "%s: raw atr=%x (%d)\n", __FUNCTION__, atr, atr);
+
+        *trim = (atr * 250) + 11000;
+
+        dev_dbg(&client->dev, "%s: real=%d\n", __FUNCTION__, *trim);
+
+        return 0;
+}
+
+struct x1205_limit
+{
+        unsigned char reg, mask, min, max;
+};
+
+static int x1205_validate_client(struct i2c_client *client)
+{
+        int i, xfer;
+
+        /* Probe array. We will read the register at the specified
+         * address and check if the given bits are zero.
+         */
+        static const unsigned char probe_zero_pattern[] = {
+                /* register, mask */
+                X1205_REG_SR,   0x18,
+                X1205_REG_DTR,  0xF8,
+                X1205_REG_ATR,  0xC0,
+                X1205_REG_INT,  0x18,
+                X1205_REG_0,    0xFF,
+        };
+
+        static const struct x1205_limit probe_limits_pattern[] = {
+                /* register, mask, min, max */
+                { X1205_REG_Y2K,        0xFF,   19,     20      },
+                { X1205_REG_DW,         0xFF,   0,      6       },
+                { X1205_REG_YR,         0xFF,   0,      99      },
+                { X1205_REG_MO,         0xFF,   0,      12      },
+                { X1205_REG_DT,         0xFF,   0,      31      },
+                { X1205_REG_HR,         0x7F,   0,      23      },
+                { X1205_REG_MN,         0xFF,   0,      59      },
+                { X1205_REG_SC,         0xFF,   0,      59      },
+                { X1205_REG_Y2K1,       0xFF,   19,     20      },
+                { X1205_REG_Y2K0,       0xFF,   19,     20      },
+        };
+
+        /* check that registers have bits a 0 where expected */
+        for (i = 0; i < ARRAY_SIZE(probe_zero_pattern); i += 2) {
+                unsigned char buf;
+
+                unsigned char addr[2] = { 0, probe_zero_pattern[i] };
+
+                struct i2c_msg msgs[2] = {
+                        { client->addr, 0, 2, addr },
+                        { client->addr, I2C_M_RD, 1, &buf },
+                };
+
+                if ((xfer = i2c_transfer(client->adapter, msgs, 2)) != 2) {
+                        dev_err(&client->adapter->dev,
+                                "%s: could not read register %x\n",
+                                __FUNCTION__, probe_zero_pattern[i]);
+
+                        return -EIO;
+                }
+
+                if ((buf & probe_zero_pattern[i+1]) != 0) {
+                        dev_err(&client->adapter->dev,
+                                "%s: register=%02x, zero pattern=%d, value=%x\n",
+                                __FUNCTION__, probe_zero_pattern[i], i, buf);
+
+                        return -ENODEV;
+                }
+        }
+
+        /* check limits (only registers with bcd values) */
+        for (i = 0; i < ARRAY_SIZE(probe_limits_pattern); i++) {
+                unsigned char reg, value;
+
+                unsigned char addr[2] = { 0, probe_limits_pattern[i].reg };
+
+                struct i2c_msg msgs[2] = {
+                        { client->addr, 0, 2, addr },
+                        { client->addr, I2C_M_RD, 1, &reg },
+                };
+
+                if ((xfer = i2c_transfer(client->adapter, msgs, 2)) != 2) {
+                        dev_err(&client->adapter->dev,
+                                "%s: could not read register %x\n",
+                                __FUNCTION__, probe_limits_pattern[i].reg);
+
+                        return -EIO;
+                }
+
+                value = BCD2BIN(reg & probe_limits_pattern[i].mask);
+
+                if (value > probe_limits_pattern[i].max ||
+                        value < probe_limits_pattern[i].min) {
+                        dev_dbg(&client->adapter->dev,
+                                "%s: register=%x, lim pattern=%d, value=%d\n",
+                                __FUNCTION__, probe_limits_pattern[i].reg,
+                                i, value);
+
+                        return -ENODEV;
+                }
+        }
+
+        return 0;
+}
+
+static int x1205_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alrm)
+{
+        return x1205_get_datetime(to_i2c_client(dev),
+                &alrm->time, X1205_ALM0_BASE);
+}
+
+static int x1205_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alrm)
+{
+        return x1205_set_datetime(to_i2c_client(dev),
+                &alrm->time, 1, X1205_ALM0_BASE);
+}
+
+static int x1205_rtc_read_time(struct device *dev, struct rtc_time *tm)
+{
+        return x1205_get_datetime(to_i2c_client(dev),
+                tm, X1205_CCR_BASE);
+}
+
+static int x1205_rtc_set_time(struct device *dev, struct rtc_time *tm)
+{
+        return x1205_set_datetime(to_i2c_client(dev),
+                tm, 1, X1205_CCR_BASE);
+}
+
+static int x1205_rtc_proc(struct device *dev, struct seq_file *seq)
+{
+        int err, dtrim, atrim;
+
+        seq_printf(seq, "24hr\t\t: yes\n");
+
+        if ((err = x1205_get_dtrim(to_i2c_client(dev), &dtrim)) == 0)
+                seq_printf(seq, "digital_trim\t: %d ppm\n", dtrim);
+
+        if ((err = x1205_get_atrim(to_i2c_client(dev), &atrim)) == 0)
+                seq_printf(seq, "analog_trim\t: %d.%02d pF\n",
+                        atrim / 1000, atrim % 1000);
+        return 0;
+}
+
+static struct rtc_class_ops x1205_rtc_ops = {
+        .proc           = x1205_rtc_proc,
+        .read_time      = x1205_rtc_read_time,
+        .set_time       = x1205_rtc_set_time,
+        .read_alarm     = x1205_rtc_read_alarm,
+        .set_alarm      = x1205_rtc_set_alarm,
+};
+
+static ssize_t x1205_sysfs_show_atrim(struct device *dev,
+                                struct device_attribute *attr, char *buf)
+{
+        int atrim;
+
+        if (x1205_get_atrim(to_i2c_client(dev), &atrim) == 0)
+                return sprintf(buf, "%d.%02d pF\n",
+                        atrim / 1000, atrim % 1000);
+        return 0;
+}
+static DEVICE_ATTR(atrim, S_IRUGO, x1205_sysfs_show_atrim, NULL);
+
+static ssize_t x1205_sysfs_show_dtrim(struct device *dev,
+                                struct device_attribute *attr, char *buf)
+{
+        int dtrim;
+
+        if (x1205_get_dtrim(to_i2c_client(dev), &dtrim) == 0)
+                return sprintf(buf, "%d ppm\n", dtrim);
+
+        return 0;
+}
+static DEVICE_ATTR(dtrim, S_IRUGO, x1205_sysfs_show_dtrim, NULL);
+
+static int x1205_attach(struct i2c_adapter *adapter)
+{
+        dev_dbg(&adapter->dev, "%s\n", __FUNCTION__);
+        return i2c_probe(adapter, &addr_data, x1205_probe);
+}
+
+static int x1205_probe(struct i2c_adapter *adapter, int address, int kind)
+{
+        int err = 0;
+        unsigned char sr;
+        struct i2c_client *client;
+        struct rtc_device *rtc;
+
+        dev_dbg(&adapter->dev, "%s\n", __FUNCTION__);
+
+        if (!i2c_check_functionality(adapter, I2C_FUNC_I2C)) {
+                err = -ENODEV;
+                goto exit;
+        }
+
+        if (!(client = kzalloc(sizeof(struct i2c_client), GFP_KERNEL))) {
+                err = -ENOMEM;
+                goto exit;
+        }
+
+        /* I2C client */
+        client->addr = address;
+        client->driver = &x1205_driver;
+        client->adapter = adapter;
+
+        strlcpy(client->name, x1205_driver.driver.name, I2C_NAME_SIZE);
+
+        /* Verify the chip is really an X1205 */
+        if (kind < 0) {
+                if (x1205_validate_client(client) < 0) {
+                        err = -ENODEV;
+                        goto exit_kfree;
+                }
+        }
+
+        /* Inform the i2c layer */
+        if ((err = i2c_attach_client(client)))
+                goto exit_kfree;
+
+        dev_info(&client->dev, "chip found, driver version " DRV_VERSION "\n");
+
+        rtc = rtc_device_register(x1205_driver.driver.name, &client->dev,
+                                &x1205_rtc_ops, THIS_MODULE);
+
+        if (IS_ERR(rtc)) {
+                err = PTR_ERR(rtc);
+                dev_err(&client->dev,
+                        "unable to register the class device\n");
+                goto exit_detach;
+        }
+
+        i2c_set_clientdata(client, rtc);
+
+        /* Check for power failures and eventualy enable the osc */
+        if ((err = x1205_get_status(client, &sr)) == 0) {
+                if (sr & X1205_SR_RTCF) {
+                        dev_err(&client->dev,
+                                "power failure detected, "
+                                "please set the clock\n");
+                        udelay(50);
+                        x1205_fix_osc(client);
+                }
+        }
+        else
+                dev_err(&client->dev, "couldn't read status\n");
+
+        device_create_file(&client->dev, &dev_attr_atrim);
+        device_create_file(&client->dev, &dev_attr_dtrim);
+
+        return 0;
+
+exit_detach:
+        i2c_detach_client(client);
+
+exit_kfree:
+        kfree(client);
+
+exit:
+        return err;
+}
+
+static int x1205_detach(struct i2c_client *client)
+{
+        int err;
+        struct rtc_device *rtc = i2c_get_clientdata(client);
+
+        dev_dbg(&client->dev, "%s\n", __FUNCTION__);
+
+        if (rtc)
+                rtc_device_unregister(rtc);
+
+        if ((err = i2c_detach_client(client)))
+                return err;
+
+        kfree(client);
+
+        return 0;
+}
+
+static int __init x1205_init(void)
+{
+        return i2c_add_driver(&x1205_driver);
+}
+
+static void __exit x1205_exit(void)
+{
+        i2c_del_driver(&x1205_driver);
+}
+
+MODULE_AUTHOR(
+        "Karen Spearel <kas111 at gmail dot com>, "
+        "Alessandro Zummo <a.zummo@towertech.it>");
+MODULE_DESCRIPTION("Xicor/Intersil X1205 RTC driver");
+MODULE_LICENSE("GPL");
+MODULE_VERSION(DRV_VERSION);
+
+module_init(x1205_init);
+module_exit(x1205_exit);