rtc-pcf2123.c

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/*
 * An SPI driver for the Philips PCF2123 RTC
 * Copyright 2009 Cyber Switching, Inc.
 *
 * Author: Chris Verges <[email protected]>
 * Maintainers: http://www.cyberswitching.com
 *
 * based on the RS5C348 driver in this same directory.
 *
 * Thanks to Christian Pellegrin <[email protected]> for
 * the sysfs contributions to this driver.
 *
 * 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.
 *
 * Please note that the CS is active high, so platform data
 * should look something like:
 *
 * static struct spi_board_info ek_spi_devices[] = {
 *  ...
 *  {
 *      .modalias       = "rtc-pcf2123",
 *      .chip_select        = 1,
 *      .controller_data    = (void *)AT91_PIN_PA10,
 *      .max_speed_hz       = 1000 * 1000,
 *      .mode           = SPI_CS_HIGH,
 *      .bus_num        = 0,
 *  },
 *  ...
 *};
 *
 */

#include <linux/bcd.h>
#include <linux/delay.h>
#include <linux/device.h>
#include <linux/errno.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/string.h>
#include <linux/slab.h>
#include <linux/rtc.h>
#include <linux/spi/spi.h>
#include <linux/module.h>
#include <linux/sysfs.h>

#define DRV_VERSION "0.6"

#define PCF2123_REG_CTRL1   (0x00)  /* Control Register 1 */
#define PCF2123_REG_CTRL2   (0x01)  /* Control Register 2 */
#define PCF2123_REG_SC      (0x02)  /* datetime */
#define PCF2123_REG_MN      (0x03)
#define PCF2123_REG_HR      (0x04)
#define PCF2123_REG_DM      (0x05)
#define PCF2123_REG_DW      (0x06)
#define PCF2123_REG_MO      (0x07)
#define PCF2123_REG_YR      (0x08)

#define PCF2123_SUBADDR     (1 << 4)
#define PCF2123_WRITE       ((0 << 7) | PCF2123_SUBADDR)
#define PCF2123_READ        ((1 << 7) | PCF2123_SUBADDR)

static struct spi_driver pcf2123_driver;

struct pcf2123_sysfs_reg {
    struct device_attribute attr;
    char name[2];
};

struct pcf2123_plat_data {
    struct rtc_device *rtc;
    struct pcf2123_sysfs_reg regs[16];
};

/*
 * Causes a 30 nanosecond delay to ensure that the PCF2123 chip select
 * is released properly after an SPI write.  This function should be
 * called after EVERY read/write call over SPI.
 */
static inline void pcf2123_delay_trec(void)
{
    ndelay(30);
}

static ssize_t pcf2123_show(struct device *dev, struct device_attribute *attr,
                char *buffer)
{
    struct spi_device *spi = to_spi_device(dev);
    struct pcf2123_sysfs_reg *r;
    u8 txbuf[1], rxbuf[1];
    unsigned long reg;
    int ret;

    r = container_of(attr, struct pcf2123_sysfs_reg, attr);

    if (strict_strtoul(r->name, 16, &reg))
        return -EINVAL;

    txbuf[0] = PCF2123_READ | reg;
    ret = spi_write_then_read(spi, txbuf, 1, rxbuf, 1);
    if (ret < 0)
        return -EIO;
    pcf2123_delay_trec();
    return sprintf(buffer, "0x%x\n", rxbuf[0]);
}

static ssize_t pcf2123_store(struct device *dev, struct device_attribute *attr,
                 const char *buffer, size_t count) {
    struct spi_device *spi = to_spi_device(dev);
    struct pcf2123_sysfs_reg *r;
    u8 txbuf[2];
    unsigned long reg;
    unsigned long val;

    int ret;

    r = container_of(attr, struct pcf2123_sysfs_reg, attr);

    if (strict_strtoul(r->name, 16, &reg)
        || strict_strtoul(buffer, 10, &val))
        return -EINVAL;

    txbuf[0] = PCF2123_WRITE | reg;
    txbuf[1] = val;
    ret = spi_write(spi, txbuf, sizeof(txbuf));
    if (ret < 0)
        return -EIO;
    pcf2123_delay_trec();
    return count;
}

static int pcf2123_rtc_read_time(struct device *dev, struct rtc_time *tm)
{
    struct spi_device *spi = to_spi_device(dev);
    u8 txbuf[1], rxbuf[7];
    int ret;

    txbuf[0] = PCF2123_READ | PCF2123_REG_SC;
    ret = spi_write_then_read(spi, txbuf, sizeof(txbuf),
            rxbuf, sizeof(rxbuf));
    if (ret < 0)
        return ret;
    pcf2123_delay_trec();

    tm->tm_sec = bcd2bin(rxbuf[0] & 0x7F);
    tm->tm_min = bcd2bin(rxbuf[1] & 0x7F);
    tm->tm_hour = bcd2bin(rxbuf[2] & 0x3F); /* rtc hr 0-23 */
    tm->tm_mday = bcd2bin(rxbuf[3] & 0x3F);
    tm->tm_wday = rxbuf[4] & 0x07;
    tm->tm_mon = bcd2bin(rxbuf[5] & 0x1F) - 1; /* rtc mn 1-12 */
    tm->tm_year = bcd2bin(rxbuf[6]);
    if (tm->tm_year < 70)
        tm->tm_year += 100; /* assume we are in 1970...2069 */

    dev_dbg(dev, "%s: tm is secs=%d, mins=%d, hours=%d, "
            "mday=%d, mon=%d, year=%d, wday=%d\n",
            __func__,
            tm->tm_sec, tm->tm_min, tm->tm_hour,
            tm->tm_mday, tm->tm_mon, tm->tm_year, tm->tm_wday);

    /* the clock can give out invalid datetime, but we cannot return
     * -EINVAL otherwise hwclock will refuse to set the time on bootup.
     */
    if (rtc_valid_tm(tm) < 0)
        dev_err(dev, "retrieved date/time is not valid.\n");

    return 0;
}

static int pcf2123_rtc_set_time(struct device *dev, struct rtc_time *tm)
{
    struct spi_device *spi = to_spi_device(dev);
    u8 txbuf[8];
    int ret;

    dev_dbg(dev, "%s: tm is secs=%d, mins=%d, hours=%d, "
            "mday=%d, mon=%d, year=%d, wday=%d\n",
            __func__,
            tm->tm_sec, tm->tm_min, tm->tm_hour,
            tm->tm_mday, tm->tm_mon, tm->tm_year, tm->tm_wday);

    /* Stop the counter first */
    txbuf[0] = PCF2123_WRITE | PCF2123_REG_CTRL1;
    txbuf[1] = 0x20;
    ret = spi_write(spi, txbuf, 2);
    if (ret < 0)
        return ret;
    pcf2123_delay_trec();

    /* Set the new time */
    txbuf[0] = PCF2123_WRITE | PCF2123_REG_SC;
    txbuf[1] = bin2bcd(tm->tm_sec & 0x7F);
    txbuf[2] = bin2bcd(tm->tm_min & 0x7F);
    txbuf[3] = bin2bcd(tm->tm_hour & 0x3F);
    txbuf[4] = bin2bcd(tm->tm_mday & 0x3F);
    txbuf[5] = tm->tm_wday & 0x07;
    txbuf[6] = bin2bcd((tm->tm_mon + 1) & 0x1F); /* rtc mn 1-12 */
    txbuf[7] = bin2bcd(tm->tm_year < 100 ? tm->tm_year : tm->tm_year - 100);

    ret = spi_write(spi, txbuf, sizeof(txbuf));
    if (ret < 0)
        return ret;
    pcf2123_delay_trec();

    /* Start the counter */
    txbuf[0] = PCF2123_WRITE | PCF2123_REG_CTRL1;
    txbuf[1] = 0x00;
    ret = spi_write(spi, txbuf, 2);
    if (ret < 0)
        return ret;
    pcf2123_delay_trec();

    return 0;
}

static const struct rtc_class_ops pcf2123_rtc_ops = {
    .read_time  = pcf2123_rtc_read_time,
    .set_time   = pcf2123_rtc_set_time,
};

static int __devinit pcf2123_probe(struct spi_device *spi)
{
    struct rtc_device *rtc;
    struct pcf2123_plat_data *pdata;
    u8 txbuf[2], rxbuf[2];
    int ret, i;

    pdata = kzalloc(sizeof(struct pcf2123_plat_data), GFP_KERNEL);
    if (!pdata)
        return -ENOMEM;
    spi->dev.platform_data = pdata;

    /* Send a software reset command */
    txbuf[0] = PCF2123_WRITE | PCF2123_REG_CTRL1;
    txbuf[1] = 0x58;
    dev_dbg(&spi->dev, "resetting RTC (0x%02X 0x%02X)\n",
            txbuf[0], txbuf[1]);
    ret = spi_write(spi, txbuf, 2 * sizeof(u8));
    if (ret < 0)
        goto kfree_exit;
    pcf2123_delay_trec();

    /* Stop the counter */
    txbuf[0] = PCF2123_WRITE | PCF2123_REG_CTRL1;
    txbuf[1] = 0x20;
    dev_dbg(&spi->dev, "stopping RTC (0x%02X 0x%02X)\n",
            txbuf[0], txbuf[1]);
    ret = spi_write(spi, txbuf, 2 * sizeof(u8));
    if (ret < 0)
        goto kfree_exit;
    pcf2123_delay_trec();

    /* See if the counter was actually stopped */
    txbuf[0] = PCF2123_READ | PCF2123_REG_CTRL1;
    dev_dbg(&spi->dev, "checking for presence of RTC (0x%02X)\n",
            txbuf[0]);
    ret = spi_write_then_read(spi, txbuf, 1 * sizeof(u8),
                    rxbuf, 2 * sizeof(u8));
    dev_dbg(&spi->dev, "received data from RTC (0x%02X 0x%02X)\n",
            rxbuf[0], rxbuf[1]);
    if (ret < 0)
        goto kfree_exit;
    pcf2123_delay_trec();

    if (!(rxbuf[0] & 0x20)) {
        dev_err(&spi->dev, "chip not found\n");
        goto kfree_exit;
    }

    dev_info(&spi->dev, "chip found, driver version " DRV_VERSION "\n");
    dev_info(&spi->dev, "spiclk %u KHz.\n",
            (spi->max_speed_hz + 500) / 1000);

    /* Start the counter */
    txbuf[0] = PCF2123_WRITE | PCF2123_REG_CTRL1;
    txbuf[1] = 0x00;
    ret = spi_write(spi, txbuf, sizeof(txbuf));
    if (ret < 0)
        goto kfree_exit;
    pcf2123_delay_trec();

    /* Finalize the initialization */
    rtc = rtc_device_register(pcf2123_driver.driver.name, &spi->dev,
            &pcf2123_rtc_ops, THIS_MODULE);

    if (IS_ERR(rtc)) {
        dev_err(&spi->dev, "failed to register.\n");
        ret = PTR_ERR(rtc);
        goto kfree_exit;
    }

    pdata->rtc = rtc;

    for (i = 0; i < 16; i++) {
        sysfs_attr_init(&pdata->regs[i].attr.attr);
        sprintf(pdata->regs[i].name, "%1x", i);
        pdata->regs[i].attr.attr.mode = S_IRUGO | S_IWUSR;
        pdata->regs[i].attr.attr.name = pdata->regs[i].name;
        pdata->regs[i].attr.show = pcf2123_show;
        pdata->regs[i].attr.store = pcf2123_store;
        ret = device_create_file(&spi->dev, &pdata->regs[i].attr);
        if (ret) {
            dev_err(&spi->dev, "Unable to create sysfs %s\n",
                pdata->regs[i].name);
            goto sysfs_exit;
        }
    }

    return 0;

sysfs_exit:
    for (i--; i >= 0; i--)
        device_remove_file(&spi->dev, &pdata->regs[i].attr);

kfree_exit:
    kfree(pdata);
    spi->dev.platform_data = NULL;
    return ret;
}

static int __devexit pcf2123_remove(struct spi_device *spi)
{
    struct pcf2123_plat_data *pdata = spi->dev.platform_data;
    int i;

    if (pdata) {
        struct rtc_device *rtc = pdata->rtc;

        if (rtc)
            rtc_device_unregister(rtc);
        for (i = 0; i < 16; i++)
            if (pdata->regs[i].name[0])
                device_remove_file(&spi->dev,
                           &pdata->regs[i].attr);
        kfree(pdata);
    }

    return 0;
}

static struct spi_driver pcf2123_driver = {
    .driver = {
            .name   = "rtc-pcf2123",
            .owner  = THIS_MODULE,
    },
    .probe  = pcf2123_probe,
    .remove = __devexit_p(pcf2123_remove),
};

module_spi_driver(pcf2123_driver);

MODULE_AUTHOR("Chris Verges <[email protected]>");
MODULE_DESCRIPTION("NXP PCF2123 RTC driver");
MODULE_LICENSE("GPL");
MODULE_VERSION(DRV_VERSION);