/*
 * An SPI driver for the Philips PCF2123 RTC
 * Copyright 2009 Cyber Switching, Inc.
 *
 * Author: Chris Verges <chrisv@cyberswitching.com>
 * Maintainers: http://www.cyberswitching.com
 *
 * based on the RS5C348 driver in this same directory.
 *
 * Thanks to Christian Pellegrin <chripell@fsfe.org> 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/rtc.h>
#include <linux/spi/spi.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++) {
                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 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",
                        .bus    = &spi_bus_type,
                        .owner  = THIS_MODULE,
        },
        .probe  = pcf2123_probe,
        .remove = __devexit_p(pcf2123_remove),
};

static int __init pcf2123_init(void)
{
        return spi_register_driver(&pcf2123_driver);
}

static void __exit pcf2123_exit(void)
{
        spi_unregister_driver(&pcf2123_driver);
}

MODULE_AUTHOR("Chris Verges <chrisv@cyberswitching.com>");
MODULE_DESCRIPTION("NXP PCF2123 RTC driver");
MODULE_LICENSE("GPL");
MODULE_VERSION(DRV_VERSION);

module_init(pcf2123_init);
module_exit(pcf2123_exit);