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Message-ID: <20081014101703.1ded0259@i1501.lan.towertech.it>
Date: Tue, 14 Oct 2008 10:17:03 +0200
From: Alessandro Zummo <alessandro.zummo@...ertech.it>
To: Mark Jackson <mpfj@...c.co.uk>
Cc: <rtc-linux@...glegroups.com>, lkml <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] Add Dallas DS1390 RTC chip
On Tue, 14 Oct 2008 09:05:18 +0100
Mark Jackson <mpfj@...c.co.uk> wrote:
Hi Mark,
a few notes below:
> +#include <linux/module.h>
> +#include <linux/version.h>
> +
> +#include <linux/kernel.h>
> +#include <linux/platform_device.h>
> +#include <linux/init.h>
> +#include <linux/rtc.h>
> +#include <linux/spi/spi.h>
> +#include <linux/bcd.h>
> +#include <linux/delay.h>
Please check that you require all of those includes.
> +struct ds1390
> +{
> + struct rtc_device *rtc;
> + u8 buf[9]; /* cmd + 8 registers */
> + u8 tx_buf[2];
> + u8 rx_buf[2];
> +};
> +
> +static void ds1390_set_reg(struct device *dev, unsigned char address,
> + unsigned char data)
> +{
> + struct spi_device *spi = to_spi_device(dev);
> + unsigned char buf[2];
> +
> + /* MSB must be '1' to write */
> + buf[0] = address | 0x80;
> + buf[1] = data;
> +
> + spi_write(spi, buf, 2);
> +}
> +
> +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);
> + struct spi_message message;
> + struct spi_transfer xfer;
> + int status;
> +
> + if (!data)
> + return -EINVAL;
> +
> + /* Build our spi message */
> + spi_message_init(&message);
> + memset(&xfer, 0, sizeof(xfer));
> + xfer.len = 2;
> + /* Can tx_buf and rx_buf be equal? The doc in spi.h is not sure... */
> + xfer.tx_buf = chip->tx_buf;
> + xfer.rx_buf = chip->rx_buf;
you use the same buffer a few functions below. either
one way or the other. please investigate with the spi subsystem maintainer.
> +
> + /* Clear MSB to indicate read */
> + chip->tx_buf[0] = address & 0x7f;
> +
> + spi_message_add_tail(&xfer, &message);
> +
> + /* do the i/o */
> + status = spi_sync(spi, &message);
> + if (status == 0)
> + {
> + status = message.status;
> + }
> + else
> + {
> + return status;
> + }
should be cleaner in this way:
if (status != 0)
return status;
*data = chip->rx_buf[1];
return message.status;
> +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);
> + struct spi_message message;
> + struct spi_transfer xfer;
> + int status;
> +
> + /* build the message */
> + spi_message_init(&message);
> + memset(&xfer, 0, sizeof(xfer));
> + xfer.len = 1 + 7; /* read command + 7 registers */
> + xfer.tx_buf = chip->buf;
> + xfer.rx_buf = chip->buf;
the buffer mentioned above.
> + chip->buf[0] = DS1390_REG_SECONDS;
> + spi_message_add_tail(&xfer, &message);
> +
> + /* do the i/o */
> + status = spi_sync(spi, &message);
> + if (status == 0)
> + {
> + status = message.status;
> + }
> + else
> + {
> + return status;
> + }
ditto.
> + /* The chip sends data in this order:
> + * Seconds, Minutes, Hours, Day, Date, Month / Century, Year */
> + dt->tm_sec = BCD2BIN(chip->buf[1]);
> + dt->tm_min = BCD2BIN(chip->buf[2]);
> + dt->tm_hour = BCD2BIN(chip->buf[3]);
> + dt->tm_wday = BCD2BIN(chip->buf[4]);
> + dt->tm_mday = BCD2BIN(chip->buf[5]);
> + /* mask off century bit */
> + dt->tm_mon = BCD2BIN(chip->buf[6] & 0x7f) - 1;
> + /* adjust for century bit */
> + dt->tm_year = BCD2BIN(chip->buf[7]) + ((chip->buf[6] & 0x80) ? 100 : 0);
> +
> + return 0;
> +}
> +
> +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);
> + struct spi_message message;
> + struct spi_transfer xfer;
> + int status;
> +
> + /* build the message */
> + spi_message_init(&message);
> + memset(&xfer, 0, sizeof(xfer));
> + xfer.len = 1 + 8; /* write command + 8 registers */
> + xfer.tx_buf = chip->buf;
> + xfer.rx_buf = chip->buf;
> + chip->buf[0] = DS1390_REG_SECONDS | 0x80;
> + chip->buf[1] = BIN2BCD(dt->tm_sec);
> + chip->buf[2] = BIN2BCD(dt->tm_min);
> + chip->buf[3] = BIN2BCD(dt->tm_hour);
> + chip->buf[4] = BIN2BCD(dt->tm_wday);
> + chip->buf[5] = BIN2BCD(dt->tm_mday);
> + chip->buf[6] = BIN2BCD(dt->tm_mon + 1) | ((dt->tm_year > 99) ? 0x80 : 0x00);
> + chip->buf[7] = BIN2BCD(dt->tm_year % 100);
> + spi_message_add_tail(&xfer, &message);
> +
> + /* do the i/o */
> + status = spi_sync(spi, &message);
> + if (status == 0)
> + {
> + status = message.status;
> + }
> + else
> + {
> + return status;
> + }
if status == 0, status is not used anymore, so you can
just return if != 0;
> + return 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("DS1390 SPI RTC driver\n");
> +
> + rtc = rtc_device_register("ds1390",
> + &spi->dev, &ds1390_rtc_ops, THIS_MODULE);
> + if (IS_ERR(rtc))
> + {
> + printk("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("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("RTC : unable to read device\n");
> + 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",
> + .bus = &spi_bus_type,
> + .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 SPI RTC driver");
> +MODULE_AUTHOR ("Mark Jackson");
you email here please.
> +MODULE_LICENSE ("GPL");
--
Best regards,
Alessandro Zummo,
Tower Technologies - Torino, Italy
http://www.towertech.it
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