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Date: Tue, 24 Nov 2015 23:16:26 +0100
From: Alexandre Belloni <alexandre.belloni@...e-electrons.com>
To: Joshua Clayton <stillcompiling@...il.com>
Cc: Alessandro Zummo <a.zummo@...ertech.it>,
rtc-linux@...glegroups.com, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 3/9] rtc-pcf2123: clean up writes to the rtc chip
On 04/11/2015 at 07:36:34 -0800, Joshua Clayton wrote :
> +static int pcf2123_write(struct device *dev, u8 *txbuf, size_t size)
> +{
> + struct spi_device *spi = to_spi_device(dev);
> + int ret;
> +
> + if (txbuf[0] > PCF2123_REG_MAX)
> + return -EFAULT;
> +
Is that test really necessary? From what I understand the driver always
controls which register is written.
> + txbuf[0] |= PCF2123_WRITE;
> + ret = spi_write(spi, txbuf, size);
> + pcf2123_delay_trec();
> +
> + return ret;
> +}
> +
> +static int pcf2123_write_reg(struct device *dev, u8 reg, u8 val)
> +{
> + u8 txbuf[2];
> +
> + txbuf[0] = reg;
> + txbuf[1] = val;
> + return pcf2123_write(dev, txbuf, sizeof(txbuf));
> +}
> +
> static ssize_t pcf2123_show(struct device *dev, struct device_attribute *attr,
> char *buffer)
> {
> @@ -142,9 +166,7 @@ static ssize_t pcf2123_show(struct device *dev, struct device_attribute *attr,
>
> 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;
>
> @@ -160,12 +182,9 @@ static ssize_t pcf2123_store(struct device *dev, struct device_attribute *attr,
> if (ret)
> return ret;
>
> - txbuf[0] = PCF2123_WRITE | reg;
> - txbuf[1] = val;
> - ret = spi_write(spi, txbuf, sizeof(txbuf));
> + pcf2123_write_reg(dev, reg, val);
> if (ret < 0)
> return -EIO;
> - pcf2123_delay_trec();
> return count;
> }
>
> @@ -205,7 +224,6 @@ static int pcf2123_rtc_read_time(struct device *dev, struct rtc_time *tm)
>
> 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;
>
> @@ -216,15 +234,12 @@ static int pcf2123_rtc_set_time(struct device *dev, struct rtc_time *tm)
> 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);
> + ret = pcf2123_write_reg(dev, PCF2123_REG_CTRL1, 0x20);
> if (ret < 0)
> return ret;
> - pcf2123_delay_trec();
>
> /* Set the new time */
> - txbuf[0] = PCF2123_WRITE | PCF2123_REG_SC;
> + txbuf[0] = PCF2123_REG_SC;
> txbuf[1] = bin2bcd(tm->tm_sec & 0x7F);
> txbuf[2] = bin2bcd(tm->tm_min & 0x7F);
> txbuf[3] = bin2bcd(tm->tm_hour & 0x3F);
> @@ -233,18 +248,14 @@ static int pcf2123_rtc_set_time(struct device *dev, struct rtc_time *tm)
> 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));
> + ret = pcf2123_write(dev, 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);
> + ret = pcf2123_write_reg(dev, PCF2123_REG_CTRL1, 0x00);
> if (ret < 0)
> return ret;
> - pcf2123_delay_trec();
>
> return 0;
> }
> @@ -258,7 +269,7 @@ static int pcf2123_probe(struct spi_device *spi)
> {
> struct rtc_device *rtc;
> struct pcf2123_plat_data *pdata;
> - u8 txbuf[2], rxbuf[2];
> + u8 rxbuf[2];
> int ret, i;
>
> pdata = devm_kzalloc(&spi->dev, sizeof(struct pcf2123_plat_data),
> @@ -268,24 +279,16 @@ static int pcf2123_probe(struct spi_device *spi)
> 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));
> + dev_dbg(&spi->dev, "resetting RTC\n");
> + ret = pcf2123_write_reg(&spi->dev, PCF2123_REG_CTRL1, 0x58);
> 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));
> + dev_dbg(&spi->dev, "stopping RTC\n");
> + ret = pcf2123_write_reg(&spi->dev, PCF2123_REG_CTRL1, 0x20);
> if (ret < 0)
> goto kfree_exit;
> - pcf2123_delay_trec();
>
> /* See if the counter was actually stopped */
> dev_dbg(&spi->dev, "checking for presence of RTC\n");
> @@ -306,12 +309,9 @@ static int pcf2123_probe(struct spi_device *spi)
> (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));
> + ret = pcf2123_write_reg(&spi->dev, PCF2123_REG_CTRL1, 0x00);
> if (ret < 0)
> goto kfree_exit;
> - pcf2123_delay_trec();
>
> /* Finalize the initialization */
> rtc = devm_rtc_device_register(&spi->dev, pcf2123_driver.driver.name,
> --
> 2.5.0
>
--
Alexandre Belloni, Free Electrons
Embedded Linux, Kernel and Android engineering
http://free-electrons.com
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