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Date: Tue, 21 Oct 2008 15:37:52 -0700
From: Andrew Morton <akpm@...ux-foundation.org>
To: Mark Jackson <mpfj@...c.co.uk>
Cc: dbrownell@...rs.sourceforge.net, linux-kernel@...r.kernel.org,
alessandro.zummo@...ertech.it, rtc-linux@...glegroups.com,
spi-devel-general@...ts.sourceforge.net
Subject: Re: [PATCH v4] Add Dallas DS1390/93/94 RTC chips
On Tue, 21 Oct 2008 12:41:45 +0100
Mark Jackson <mpfj@...c.co.uk> wrote:
> v4 of this patch with some code tidying as per previous comments.
> Also only a single tx/rx buffer is used.
> Now uses spi_write_then_read()
> Comments changed to include extra chips in the family
>
> This patch adds support for the Dallas DS1390/93/94 SPI RTC chip.
>
A neat-looking driver. Some nitlets:
> +
> +#define DS1390_REG_ALARM_100THS 0x08
> +#define DS1390_REG_ALARM_SECONDS 0x09
> +#define DS1390_REG_ALARM_MINUTES 0x0A
> +#define DS1390_REG_ALARM_HOURS 0x0B
> +#define DS1390_REG_ALARM_DAY_DATE 0x0C
> +
> +#define DS1390_REG_CONTROL 0x0D
> +#define DS1390_REG_STATUS 0x0E
> +#define DS1390_REG_TRICKLE 0x0F
> +
> +struct ds1390 {
> + struct rtc_device *rtc;
> + u8 txrx_buf[9]; /* cmd + 8 registers */
> +};
> +
> +static void ds1390_set_reg(struct device *dev, unsigned char address,
> + unsigned char data)
> +{
> + struct spi_device *spi = to_spi_device(dev);
> + struct ds1390 *chip = dev_get_drvdata(dev);
> +
> + /* Set MSB to indicate write */
> + chip->txrx_buf[0] = address | 0x80;
> + chip->txrx_buf[1] = data;
> +
> + /* do the i/o */
> + spi_write_then_read(spi, chip->txrx_buf, 2, NULL, 0);
> +}
> +
> +static int ds1390_get_reg(struct device *dev, unsigned char address,
> + unsigned char *data)
> +{
> + struct spi_device *spi = to_spi_device(dev);
> + struct ds1390 *chip = dev_get_drvdata(dev);
> + int status;
> +
> + if (!data)
> + return -EINVAL;
This function only has one caller and that caller doesn't pass NULL, so
this test is unneeded.
> + /* Clear MSB to indicate read */
> + chip->txrx_buf[0] = address & 0x7f;
> + /* do the i/o */
> + status = spi_write_then_read(spi, chip->txrx_buf, 1, chip->txrx_buf, 1);
> + if (status != 0)
> + return status;
> +
> + *data = chip->txrx_buf[1];
> +
> + return 0;
> +}
> +
> +static int ds1390_get_datetime(struct device *dev, struct rtc_time *dt)
> +{
> + struct spi_device *spi = to_spi_device(dev);
> + struct ds1390 *chip = dev_get_drvdata(dev);
> + int status;
> +
> + /* build the message */
> + chip->txrx_buf[0] = DS1390_REG_SECONDS;
> +
> + /* do the i/o */
> + status = spi_write_then_read(spi, chip->txrx_buf, 1, chip->txrx_buf, 8);
> + if (status != 0)
> + return status;
> +
> + /* The chip sends data in this order:
> + * Seconds, Minutes, Hours, Day, Date, Month / Century, Year */
> + dt->tm_sec = bcd2bin(chip->txrx_buf[0]);
> + dt->tm_min = bcd2bin(chip->txrx_buf[1]);
> + dt->tm_hour = bcd2bin(chip->txrx_buf[2]);
> + dt->tm_wday = bcd2bin(chip->txrx_buf[3]);
> + dt->tm_mday = bcd2bin(chip->txrx_buf[4]);
> + /* mask off century bit */
> + dt->tm_mon = bcd2bin(chip->txrx_buf[5] & 0x7f) - 1;
> + /* adjust for century bit */
> + dt->tm_year = bcd2bin(chip->txrx_buf[6]) + ((chip->txrx_buf[5] & 0x80) ? 100 : 0);
> +
> + return rtc_valid_tm(dt);
> +}
> +
> +static int ds1390_set_datetime(struct device *dev, struct rtc_time *dt)
> +{
> + struct spi_device *spi = to_spi_device(dev);
> + struct ds1390 *chip = dev_get_drvdata(dev);
> +
> + /* build the message */
> + chip->txrx_buf[0] = DS1390_REG_SECONDS | 0x80;
> + chip->txrx_buf[1] = bin2bcd(dt->tm_sec);
> + chip->txrx_buf[2] = bin2bcd(dt->tm_min);
> + chip->txrx_buf[3] = bin2bcd(dt->tm_hour);
> + chip->txrx_buf[4] = bin2bcd(dt->tm_wday);
> + chip->txrx_buf[5] = bin2bcd(dt->tm_mday);
> + chip->txrx_buf[6] = bin2bcd(dt->tm_mon + 1) |
> + ((dt->tm_year > 99) ? 0x80 : 0x00);
> + chip->txrx_buf[7] = bin2bcd(dt->tm_year % 100);
> +
> + /* do the i/o */
> + return spi_write_then_read(spi, chip->txrx_buf, 8, NULL, 0);
> +}
> +
> +static int ds1390_read_time(struct device *dev, struct rtc_time *tm)
> +{
> + return ds1390_get_datetime(dev, tm);
> +}
> +
> +static int ds1390_set_time(struct device *dev, struct rtc_time *tm)
> +{
> + return ds1390_set_datetime(dev, tm);
> +}
> +
> +static const struct rtc_class_ops ds1390_rtc_ops = {
> + .read_time = ds1390_read_time,
> + .set_time = ds1390_set_time,
> +};
> +
> +static int __devinit ds1390_probe(struct spi_device *spi)
> +{
> + struct rtc_device *rtc;
> + unsigned char tmp;
> + struct ds1390 *chip;
> + int res;
> +
> + printk(KERN_DEBUG "DS1390 SPI RTC driver\n");
Should be KERN_INFO I guess.
> + rtc = rtc_device_register("ds1390",
> + &spi->dev, &ds1390_rtc_ops, THIS_MODULE);
> + if (IS_ERR(rtc)) {
> + printk(KERN_ALERT "RTC : unable to register device\n");
> + return PTR_ERR(rtc);
> + }
> +
> + spi->mode = SPI_MODE_3;
> + spi->bits_per_word = 8;
> + spi_setup(spi);
> +
> + chip = kzalloc(sizeof *chip, GFP_KERNEL);
> + if (!chip) {
> + printk(KERN_ALERT "RTC : unable to allocate device memory\n");
> + rtc_device_unregister(rtc);
> + return -ENOMEM;
> + }
> + chip->rtc = rtc;
> + dev_set_drvdata(&spi->dev, chip);
> +
> + res = ds1390_get_reg(&spi->dev, DS1390_REG_SECONDS, &tmp);
> + if (res) {
> + printk(KERN_ALERT "RTC : unable to read device\n");
- Perhaps the "RTC" should identify which driver is doing the
shouting. We have a huge number of "rtc" drivers, so this message
will be rather ambiguous.
- Colons are not preceded by spaces in written English.
> + rtc_device_unregister(rtc);
> + return res;
> + }
> +
> + return 0;
> +}
> +
> +static int __devexit ds1390_remove(struct spi_device *spi)
> +{
> + struct ds1390 *chip = platform_get_drvdata(spi);
> + struct rtc_device *rtc = chip->rtc;
> +
> + if (rtc)
> + rtc_device_unregister(rtc);
> +
> + kfree(chip);
> +
> + return 0;
> +}
> +
> +static struct spi_driver ds1390_driver = {
> + .driver = {
> + .name = "rtc-ds1390",
> + .owner = THIS_MODULE,
> + },
> + .probe = ds1390_probe,
> + .remove = __devexit_p(ds1390_remove),
> +};
> +
> +static __init int ds1390_init(void)
> +{
> + return spi_register_driver(&ds1390_driver);
> +}
> +module_init(ds1390_init);
> +
> +static __exit void ds1390_exit(void)
> +{
> + spi_unregister_driver(&ds1390_driver);
> +}
> +module_exit(ds1390_exit);
> +
> +MODULE_DESCRIPTION("DS1390/93/94 SPI RTC driver");
> +MODULE_AUTHOR("Mark Jackson <mpfj@...c.co.uk>");
> +MODULE_LICENSE("GPL");
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