RTC 芯片 ISL12020M 驱动编程

1. 这段时间编了个RTC芯片ISL12020M的驱动程序，程序大部分是从ISL1208上移植过来的。寄存器地址进行了重新设置。现在已经编译通过了，还是有点成就感。嘿嘿。代码如下：
   

2.     /*
        * Intersil ISL12020M rtc class driver
        *
        *
        *
        * This program is free software; you can redistribute it and/or modify it
        * under the terms of the GNU General Public License as published by the
        * Free Software Foundation; either version 2 of the License, or (at your
        * option) any later version.
        *
        */
       #include <linux/module.h>
       #include <linux/i2c.h>
       #include <linux/bcd.h>
       #include <linux/rtc.h>
       #define DRV_NAME "isl12020m"
       #define DRV_VERSION "0.2"
       /* Register map */
       /* rtc section */
       #define ISL12020M_REG_SC 0x00
       #define ISL12020M_REG_MN 0x01
       #define ISL12020M_REG_HR 0x02
       #define ISL12020M_REG_HR_MIL (1<<7) /* 24h/12h mode */
       #define ISL12020M_REG_HR_PM (1<<5) /* PM/AM bit in 12h mode */
       #define ISL12020M_REG_DT 0x03
       #define ISL12020M_REG_MO 0x04
       #define ISL12020M_REG_YR 0x05
       #define ISL12020M_REG_DW 0x06
       #define ISL12020M_RTC_SECTION_LEN 7
       /* control/status section */
       #define ISL12020M_REG_SR 0x07 /* status reg */
       #define ISL12020M_REG_SR_DSTADJ (1<<5) /* daylight saving time change */
       #define ISL12020M_REG_SR_ALM (1<<4) /* alarm bit ,can only set 0 */
       #define ISL12020M_REG_SR_LBAT85 (1<<2) /* low battery indicator 85% */
       #define ISL12020M_REG_SR_LBAT75 (1<<1) /* low battery indicator 75% */
       #define ISL12020M_REG_SR_RTCF (1<<0) /* real time clock fail */
       #define ISL12020M_REG_INT 0x08 /* interrupt control reg */
       #define ISL12020M_REG_INT_ARST (1<<7) /* automatic reset */
       #define ISL12020M_REG_INT_WRTC (1<<6) /* write rtc enable */
       #define ISL12020M_REG_INT_IM (1<<5) /* interrupt/alarm mode */
       #define ISL12020M_REG_INT_FOBATB (1<<4) /* frequency output and interrupt */
       #define ISL12020M_REG_PWR_VDD 0x09 /* power supply control reg */
       #define ISL12020M_REG_PWR_VDD_CLRTS (1<<7) /* clear time stamp VDD to battery and time stamp battery to VDD regs */
       #define ISL12020M_REG_PWR_VBAT 0x0A /* battery voltage trip voltage reg */
       #define ISL12020M_REG_ITR0 0x0B /* initial AT and DT setting reg */
       #define ISL12020M_REG_ALPHA 0x0C /* ALPHA reg ,temperature coefficient */
       #define ISL12020M_REG_BETA 0x0D /* BETA reg, */
       #define ISL12020M_REG_BETA_TSE (1<<7) /* temperature sensor enable */
       #define ISL12020M_REG_FATR 0x0E /* final analog trimming reg */
       #define ISL12020M_REG_FDTR 0x0F /* final digital trimming reg */
       /* alarm section */
       #define ISL12020M_REG_SCA0 0x10 /* second */
       #define ISL12020M_REG_MNA0 0x11 /* minute */
       #define ISL12020M_REG_HRA0 0x12 /* hour */
       #define ISL12020M_REG_DTA0 0x13 /* date */
       #define ISL12020M_REG_MOA0 0x14 /* month */
       #define ISL12020M_REG_DWA0 0x15 /* day of week */
       #define ISL12020M_ALARM_SECTION_LEN 6
       /* TSV2B section, time stamp VDD to battery*/
       #define ISL12020M_REG_VSC 0x16
       #define ISL12020M_REG_VMN 0x17
       #define ISL12020M_REG_VHR 0x18
       #define ISL12020M_REG_VDT 0x19
       #define ISL12020M_REG_VMO 0x1A
       /* TSB2V, time stamp battery to VDD */
       #define ISL12020M_REG_BSC 0x1B
       #define ISL12020M_REG_BMN 0x1C
       #define ISL12020M_REG_BHR 0x1D
       #define ISL12020M_REG_BDT 0x1E
       #define ISL12020M_REG_BMO 0x1F
       /* DSTCR, DST control regs */
       /* DST begginning time, set forward */
       #define ISL12020M_REG_DSTMOFD 0x20
       #define ISL12020M_REG_DSTMOFD_DSTE (1<<7) /* dst enable bit */
       #define ISL12020M_REG_DSTDWFD 0x21
       #define ISL12020M_REG_DSTDWFD_DSTDWFDE (1<<6 ) /* set the priority of the day/week over the date */
       #define ISL12020M_REG_DSTDTFD 0x22
       #define ISL12020M_REG_DSTHRFD 0x23
       /* DST ending time, set backward or reverse */
       #define ISL12020M_REG_DSTMORV 0x24
       #define ISL12020M_REG_DSTDWRV 0x25
       #define ISL12020M_REG_DSTDWRV_DSTDWRVE (1<<6) /* set the priority of the day/week over the date */
       #define ISL12020M_REG_DSTDTRV 0x26
       #define ISL12020M_REG_DSTHRRV 0x27
       /* temperature regs*/
       #define ISL12020M_REG_TK0L 0x28 /*LSB 8 bit*/
       #define ISL12020M_REG_TK0M 0x29 /* MSB 2 bit */
       /* NPPM */
       #define ISL12020M_REG_NPPML 0x2A
       #define ISL12020M_REG_NPPMH 0x2B
       /* XT0 regs */
       #define ISL12020M_REG_XT0 0x2C
       /* ALPHA hot reg */
       #define ISL12020M_REG_ALPHAH 0x2D
       /* GPM section ,general purpose user sram */
       #define ISL12020M_REG_GPM1 0x2E
       #define ISL12020M_REG_GPM2 0x2F
       #define ISL12020M_GPM_SECTION_LEN 2
       /* i2c configuration */
       #define ISL12020M_I2C_ADDR 0xde /* 1101 1110*/
       static unsigned short normal_i2c[] = {
        ISL12020M_I2C_ADDR>>1, I2C_CLIENT_END
       };
       I2C_CLIENT_INSMOD; /* defines addr_data */
       static int isl12020m_attach_adapter(struct i2c_adapter *adapter);
       static int isl12020m_detach_client(struct i2c_client *client);
       static struct i2c_driver isl12020m_driver = {
        .driver = {
         .name = DRV_NAME,
        },
        .id = I2C_DRIVERID_ISL12020M,
        .attach_adapter = &isl12020m_attach_adapter,
        .detach_client = &isl12020m_detach_client,
       };
       /* block read */
       static int
       isl12020m_i2c_read_regs(struct i2c_client *client, u8 reg, u8 buf[],
                unsigned len)
       {
        u8 reg_addr[1] = { reg };
        struct i2c_msg msgs[2] = {
         { client->addr, client->flags, sizeof(reg_addr), reg_addr },
         { client->addr, client->flags | I2C_M_RD, len, buf }
        };
        int ret;
        BUG_ON(len == 0);
        BUG_ON(reg > ISL12020M_REG_GPM2);
        BUG_ON(reg + len > ISL12020M_REG_GPM2 + 1);
        ret = i2c_transfer(client->adapter, msgs, 2);
        if (ret > 0)
         ret = 0;
        return ret;
       }
       /* block write */
       static int
       isl12020m_i2c_set_regs(struct i2c_client *client, u8 reg, u8 const buf[],
                unsigned len)
       {
        u8 i2c_buf[ISL12020M_REG_GPM2 + 2];
        struct i2c_msg msgs[1] = {
         { client->addr, client->flags, len + 1, i2c_buf }
        };
        int ret;
        BUG_ON(len == 0);
        BUG_ON(reg > ISL12020M_REG_GPM2);
        BUG_ON(reg + len > ISL12020M_REG_GPM2 + 1);
        i2c_buf[0] = reg;
        memcpy(&i2c_buf[1], &buf[0], len);
        ret = i2c_transfer(client->adapter, msgs, 1);
        if (ret > 0)
         ret = 0;
        return ret;
       }
       /* simple check to see wether we have a isl12020m */
       static int isl12020m_i2c_validate_client(struct i2c_client *client)
       {
        u8 regs[ISL12020M_RTC_SECTION_LEN] = { 0, };
        u8 zero_mask[ISL12020M_RTC_SECTION_LEN] = {
         0x80, 0x80, 0x40, 0xc0, 0xe0, 0x00, 0xf8 //1000 = 8
        };
        int i;
        int ret;
        ret = isl12020m_i2c_read_regs(client, 0, regs, ISL12020M_RTC_SECTION_LEN);
        if (ret < 0)
         return ret;
        for (i = 0; i < ISL12020M_RTC_SECTION_LEN; ++i) {
         if (regs[i] & zero_mask[i]) /* check if bits are cleared */
          return -ENODEV;
        }
        return 0;
       }
       static int isl12020m_i2c_get_sr(struct i2c_client *client)
       {
        return i2c_smbus_read_byte_data(client, ISL12020M_REG_SR) == -1 ? -EIO:0;
       }
       static int isl12020m_i2c_get_fatr(struct i2c_client *client)
       {
        int fatr = i2c_smbus_read_byte_data(client, ISL12020M_REG_FATR);
        if (fatr < 0)
         return -EIO;
        /* The 6bit value in the ATR register controls the load
         * capacitance C_load * in steps of 0.25pF
         *
         * bit (1<<5) of the ATR register is inverted
         *
         * C_load(ATR=0x20) = 4.50pF
         * C_load(ATR=0x00) = 12.50pF
         * C_load(ATR=0x1f) = 20.25pF
         *
         */
        fatr &= 0x3f; /* mask out lsb */
        fatr ^= 1<<5; /* invert 6th bit */
        fatr += 2*9; /* add offset of 4.5pF; unit[atr] = 0.25pF */
        return fatr;
       }
       static int isl12020m_i2c_get_fdtr(struct i2c_client *client)
       {
        int fdtr = i2c_smbus_read_byte_data(client, ISL12020M_REG_FDTR);
        if (fdtr < 0)
         return -EIO;
        /* dtr encodes adjustments of {-60,-40,-20,0,20,40,60} ppm */
        fdtr = ((fdtr & 0x3) * 20) * (fdtr & (1<<2) ? -1 : 1);
        return fdtr;
       }
       static int isl12020m_i2c_get_gpm(struct i2c_client *client)
       {
        u8 buf[ISL12020M_GPM_SECTION_LEN] = { 0, };
        int ret;
        ret = isl12020m_i2c_read_regs (client, ISL12020M_REG_GPM1, buf,
              ISL12020M_GPM_SECTION_LEN);
        if (ret < 0)
         return ret;
        return (buf[1] << 8) | buf[0];
       }
       static int isl12020m_i2c_set_gpm(struct i2c_client *client, u16 usr)
       {
        u8 buf[ISL12020M_GPM_SECTION_LEN];
        buf[0] = usr & 0xff;
        buf[1] = (usr >> 8) & 0xff;
        return isl12020m_i2c_set_regs (client, ISL12020M_REG_GPM1, buf,
                ISL12020M_GPM_SECTION_LEN);
       }
       static int isl12020m_rtc_proc(struct device *dev, struct seq_file *seq)
       {
        struct i2c_client *const client = to_i2c_client(dev);
        int sr, fdtr, fatr, usr;
        sr = isl12020m_i2c_get_sr(client);
        if (sr < 0) {
         dev_err(&client->dev, "%s: reading SR failed\n", __func__);
         return sr;
        }
        seq_printf(seq, "status_reg\t:%s%s (0x%.2x)\n", //%s%s%s%s get out
            (sr & ISL12020M_REG_SR_RTCF) ? " RTCF" : "",
       // (sr & ISL12020M_REG_SR_BAT) ? " BAT" : "",
            (sr & ISL12020M_REG_SR_ALM) ? " ALM" : "",
       // (sr & ISL12020M_REG_SR_WRTC) ? " WRTC" : "",
       // (sr & ISL12020M_REG_SR_XTOSCB) ? " XTOSCB" : "",
       // (sr & ISL12020M_REG_SR_ARST) ? " ARST" : "",
            sr);
        seq_printf(seq, "batt_status\t: %s\n",
            (sr & ISL12020M_REG_SR_RTCF) ? "bad" : "okay");
        fdtr = isl12020m_i2c_get_fdtr(client);
        if (fdtr >= 0 -1)
         seq_printf(seq, "digital_trim\t: %d ppm\n", fdtr);
        fatr = isl12020m_i2c_get_fatr(client);
        if (fatr >= 0)
         seq_printf(seq, "analog_trim\t: %d.%.2d pF\n",
             fatr>>2, (fatr&0x3)*25);
        usr = isl12020m_i2c_get_gpm(client);
        if (usr >= 0)
         seq_printf(seq, "user_data\t: 0x%.4x\n", usr);
        return 0;
       }
       static int isl12020m_i2c_read_time(struct i2c_client *client,
            struct rtc_time *tm)
       {
        int sr;
        u8 regs[ISL12020M_RTC_SECTION_LEN] = { 0, };
        sr = isl12020m_i2c_get_sr(client);
        if (sr < 0) {
         dev_err(&client->dev, "%s: reading SR failed\n", __func__);
         return -EIO;
        }
        sr = isl12020m_i2c_read_regs(client, 0, regs, ISL12020M_RTC_SECTION_LEN);
        if (sr < 0) {
         dev_err(&client->dev, "%s: reading RTC section failed\n",
          __func__);
         return sr;
        }
        tm->tm_sec = BCD2BIN(regs[ISL12020M_REG_SC]);
        tm->tm_min = BCD2BIN(regs[ISL12020M_REG_MN]);
        { /* HR field has a more complex interpretation */
         const u8 _hr = regs[ISL12020M_REG_HR];
         if (_hr & ISL12020M_REG_HR_MIL) /* 24h format */
          tm->tm_hour = BCD2BIN(_hr & 0x3f);
         else { // 12h format
          tm->tm_hour = BCD2BIN(_hr & 0x1f);
          if (_hr & ISL12020M_REG_HR_PM) /* PM flag set */
           tm->tm_hour += 12;
         }
        }
        tm->tm_mday = BCD2BIN(regs[ISL12020M_REG_DT]);
        tm->tm_mon = BCD2BIN(regs[ISL12020M_REG_MO]) - 1; /* rtc starts at 1 */
        tm->tm_year = BCD2BIN(regs[ISL12020M_REG_YR]) + 100;
        tm->tm_wday = BCD2BIN(regs[ISL12020M_REG_DW]);
        return 0;
       }
       static int isl12020m_i2c_read_alarm(struct i2c_client *client,
             struct rtc_wkalrm *alarm)
       {
        struct rtc_time *const tm = &alarm->time;
        u8 regs[ISL12020M_ALARM_SECTION_LEN] = { 0, };
        int sr;
        sr = isl12020m_i2c_get_sr(client);
        if (sr < 0) {
         dev_err(&client->dev, "%s: reading SR failed\n", __func__);
         return sr;
        }
        sr = isl12020m_i2c_read_regs(client, ISL12020M_REG_SCA0, regs,
             ISL12020M_ALARM_SECTION_LEN);
        if (sr < 0) {
         dev_err(&client->dev, "%s: reading alarm section failed\n",
          __func__);
         return sr;
        }
        /* MSB of each alarm register is an enable bit */
        tm->tm_sec = BCD2BIN(regs[ISL12020M_REG_SCA0-ISL12020M_REG_SCA0] & 0x7f);
        tm->tm_min = BCD2BIN(regs[ISL12020M_REG_MNA0-ISL12020M_REG_SCA0] & 0x7f);
        tm->tm_hour = BCD2BIN(regs[ISL12020M_REG_HRA0-ISL12020M_REG_SCA0] & 0x3f);
        tm->tm_mday = BCD2BIN(regs[ISL12020M_REG_DTA0-ISL12020M_REG_SCA0] & 0x3f);
        tm->tm_mon = BCD2BIN(regs[ISL12020M_REG_MOA0-ISL12020M_REG_SCA0] & 0x1f)-1;
        tm->tm_wday = BCD2BIN(regs[ISL12020M_REG_DWA0-ISL12020M_REG_SCA0] & 0x03);
        return 0;
       }
       static int isl12020m_rtc_read_time(struct device *dev, struct rtc_time *tm)
       {
        return isl12020m_i2c_read_time(to_i2c_client(dev), tm);
       }
       static int isl12020m_i2c_set_time(struct i2c_client *client,
           struct rtc_time const *tm)
       {
        int sr;
        u8 regs[ISL12020M_RTC_SECTION_LEN] = { 0, };
        regs[ISL12020M_REG_SC] = BIN2BCD(tm->tm_sec);
        regs[ISL12020M_REG_MN] = BIN2BCD(tm->tm_min);
        regs[ISL12020M_REG_HR] = BIN2BCD(tm->tm_hour) | ISL12020M_REG_HR_MIL;
        regs[ISL12020M_REG_DT] = BIN2BCD(tm->tm_mday);
        regs[ISL12020M_REG_MO] = BIN2BCD(tm->tm_mon + 1);
        regs[ISL12020M_REG_YR] = BIN2BCD(tm->tm_year - 100);
        regs[ISL12020M_REG_DW] = BIN2BCD(tm->tm_wday & 7);
        sr = isl12020m_i2c_get_sr(client);
        if (sr < 0) {
         dev_err(&client->dev, "%s: reading SR failed\n", __func__);
         return sr;
        }
        /* set WRTC */
        sr = i2c_smbus_write_byte_data (client, ISL12020M_REG_SR,
                  sr | ISL12020M_REG_INT_WRTC);
        if (sr < 0) {
         dev_err(&client->dev, "%s: writing SR failed\n", __func__);
         return sr;
        }
        /* write RTC registers */
        sr = isl12020m_i2c_set_regs(client, 0, regs, ISL12020M_RTC_SECTION_LEN);
        if (sr < 0) {
         dev_err(&client->dev, "%s: writing RTC section failed\n",
          __func__);
         return sr;
        }
        /* clear WRTC again */
        sr = i2c_smbus_write_byte_data (client, ISL12020M_REG_SR,
                  sr & ~ISL12020M_REG_INT_WRTC);
        if (sr < 0) {
         dev_err(&client->dev, "%s: writing SR failed\n", __func__);
         return sr;
        }
        return 0;
       }
       static int isl12020m_rtc_set_time(struct device *dev, struct rtc_time *tm)
       {
        return isl12020m_i2c_set_time(to_i2c_client(dev), tm);
       }
       static int isl12020m_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alarm)
       {
        return isl12020m_i2c_read_alarm(to_i2c_client(dev), alarm);
       }
       static const struct rtc_class_ops isl12020m_rtc_ops = {
        .proc = isl12020m_rtc_proc,
        .read_time = isl12020m_rtc_read_time,
        .set_time = isl12020m_rtc_set_time,
        .read_alarm = isl12020m_rtc_read_alarm,
        //.set_alarm = isl1208_rtc_set_alarm,
       };
       /* sysfs interface */
       static ssize_t isl12020m_sysfs_show_atrim(struct device *dev,
            struct device_attribute *attr,
            char *buf)
       {
        int fatr;
        fatr = isl12020m_i2c_get_fatr(to_i2c_client(dev));
        if (fatr < 0)
         return fatr;
        return sprintf(buf, "%d.%.2d pF\n", fatr>>2, (fatr&0x3)*25);
       }
       static DEVICE_ATTR(atrim, S_IRUGO, isl12020m_sysfs_show_atrim, NULL);
       static ssize_t isl12020m_sysfs_show_dtrim(struct device *dev,
            struct device_attribute *attr,
            char *buf)
       {
        int fdtr;
        fdtr = isl12020m_i2c_get_fdtr(to_i2c_client(dev));
        if (fdtr < 0)
         return fdtr;
        return sprintf(buf, "%d ppm\n", fdtr);
       }
       static DEVICE_ATTR(dtrim, S_IRUGO, isl12020m_sysfs_show_dtrim, NULL);
       static ssize_t isl12020m_sysfs_show_usr(struct device *dev,
                  struct device_attribute *attr,
                  char *buf)
       {
        int usr;
        usr = isl12020m_i2c_get_gpm(to_i2c_client(dev));
        if (usr < 0)
         return usr;
        return sprintf(buf, "0x%.4x\n", usr);
       }
       static ssize_t isl12020m_sysfs_store_usr(struct device *dev,
                  struct device_attribute *attr,
                  const char *buf, size_t count)
       {
        int usr = -1;
        if (buf[0] == '0' && (buf[1] == 'x' || buf[1] == 'X')) {
         if (sscanf(buf, "%x", &usr) != 1)
          return -EINVAL;
        } else {
         if (sscanf(buf, "%d", &usr) != 1)
          return -EINVAL;
        }
        if (usr < 0 || usr > 0xffff)
         return -EINVAL;
        return isl12020m_i2c_set_gpm(to_i2c_client(dev), usr) ? -EIO : count;
       }
       static DEVICE_ATTR(usr, S_IRUGO | S_IWUSR, isl12020m_sysfs_show_usr,
            isl12020m_sysfs_store_usr);
       static int
       isl12020m_probe(struct i2c_adapter *adapter, int addr, int kind)
       {
        int rc = 0;
        struct i2c_client *new_client = NULL;
        struct rtc_device *rtc = NULL;
        if (!i2c_check_functionality(adapter, I2C_FUNC_I2C)) {
         rc = -ENODEV;
         goto failout;
        }
        new_client = kzalloc(sizeof(struct i2c_client), GFP_KERNEL);
        if (new_client == NULL) {
         rc = -ENOMEM;
         goto failout;
        }
        new_client->addr = addr;
        new_client->adapter = adapter;
        new_client->driver = &isl12020m_driver;
        new_client->flags = 0;
        strcpy(new_client->name, DRV_NAME);
        if (kind < 0) {
         rc = isl12020m_i2c_validate_client(new_client);
         if (rc < 0)
          goto failout;
        }
        rc = i2c_attach_client(new_client);
        if (rc < 0)
         goto failout;
        dev_info(&new_client->dev,
          "chip found, driver version " DRV_VERSION "\n");
        rtc = rtc_device_register(isl12020m_driver.driver.name,
             &new_client->dev,
             &isl12020m_rtc_ops, THIS_MODULE);
        if (IS_ERR(rtc)) {
         rc = PTR_ERR(rtc);
         goto failout_detach;
        }
        i2c_set_clientdata(new_client, rtc);
        rc = isl12020m_i2c_get_sr(new_client);
        if (rc < 0) {
         dev_err(&new_client->dev, "reading status failed\n");
         goto failout_unregister;
        }
        if (rc & ISL12020M_REG_SR_RTCF)
         dev_warn(&new_client->dev, "rtc power failure detected, "
           "please set clock.\n");
        rc = device_create_file(&new_client->dev, &dev_attr_atrim);
        if (rc < 0)
         goto failout_unregister;
        rc = device_create_file(&new_client->dev, &dev_attr_dtrim);
        if (rc < 0)
         goto failout_atrim;
        rc = device_create_file(&new_client->dev, &dev_attr_usr);
        if (rc < 0)
         goto failout_dtrim;
        return 0;
        failout_dtrim:
        device_remove_file(&new_client->dev, &dev_attr_dtrim);
        failout_atrim:
        device_remove_file(&new_client->dev, &dev_attr_atrim);
        failout_unregister:
        rtc_device_unregister(rtc);
        failout_detach:
        i2c_detach_client(new_client);
        failout:
        kfree(new_client);
        return rc;
       }
       static int
       isl12020m_attach_adapter (struct i2c_adapter *adapter)
       {
        return i2c_probe(adapter, &addr_data, isl12020m_probe);
       }
       static int
       isl12020m_detach_client(struct i2c_client *client)
       {
        int rc;
        struct rtc_device *const rtc = i2c_get_clientdata(client);
        if (rtc)
         rtc_device_unregister(rtc); /* do we need to kfree? */
        rc = i2c_detach_client(client);
        if (rc)
         return rc;
        kfree(client);
        return 0;
       }
       /* module management */
       static int __init isl12020m_init(void)
       {
        return i2c_add_driver(&isl12020m_driver);
       }
       static void __exit isl12020m_exit(void)
       {
        i2c_del_driver(&isl12020m_driver);
       }
       MODULE_AUTHOR("Herbert Valerio Riedel <hvr@gnu.org>");
       MODULE_DESCRIPTION("Intersil ISL12020M RTC driver");
       MODULE_LICENSE("GPL");
       MODULE_VERSION(DRV_VERSION);
       module_init(isl12020m_init);
       module_exit(isl12020m_exit);

   
   
   
3.