[rtc-linux] Re: [PATCH 2/2] rtc: rtc-pic32: Add PIC32 real time clock driver

Hi,

On 01/02/2016 at 15:43:22 -0700, Joshua Henderson wrote :

This drivers adds support for the PIC32 real time clock and calendar
peripheral:
     - reading and setting time
     - alarms when connected to an IRQ

Signed-off-by: Joshua Henderson <redacted>
---
 drivers/rtc/Kconfig     |   10 ++
 drivers/rtc/Makefile    |    1 +
 drivers/rtc/rtc-pic32.c |  450 +++++++++++++++++++++++++++++++++++++++++++++++

Nitpick: there are multiple alignment and blank lines issues that you
can spot using checkpatch --strict.

This list has to be ordered alphabetically.

This specify GPL v2 but you use MODULE_LICENSE("GPL")

+ * This program is distributed in the hope it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * for more details.
+ */
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/io.h>
+#include <linux/slab.h>
+#include <linux/clk.h>
+#include <linux/rtc.h>
+#include <linux/bcd.h>
+
+#include <asm/mach-pic32/pic32.h>
+
+#define DRIVER_NAME "pic32-rtc"
+
+#define PIC32_RTCCON		(0x00)

You probably don't need those parenthesis.

+#define PIC32_RTCCON_ON		BIT(15)
+#define PIC32_RTCCON_SIDL	BIT(13)
+#define PIC32_RTCCON_RTCCLKSEL	(3 << 9)
+#define PIC32_RTCCON_RTCCLKON	BIT(6)
+#define PIC32_RTCCON_RTCWREN	BIT(3)
+#define PIC32_RTCCON_RTCSYNC	BIT(2)
+#define PIC32_RTCCON_HALFSEC	BIT(1)
+#define PIC32_RTCCON_RTCOE	BIT(0)
+
+#define PIC32_RTCALRM		(0x10)

ditto

+#define PIC32_RTCALRM_ALRMEN	BIT(15)
+#define PIC32_RTCALRM_CHIME	BIT(14)
+#define PIC32_RTCALRM_PIV	BIT(13)
+#define PIC32_RTCALRM_ALARMSYNC	BIT(12)
+#define PIC32_RTCALRM_AMASK	(0x0F << 8)
+#define PIC32_RTCALRM_ARPT	(0xFF << 0)

Nit: For those masks, you can use genmask() or directly 0x0F00 and 0xFF

+struct pic32_rtc_dev {
+	struct rtc_device	*rtc;
+	void __iomem		*reg_base;
+	struct clk		*clk;
+	spinlock_t		flags_lock;

flags_lock is unnecessary, it is used only in one function that is
called only at probe time

+	spinlock_t		alarm_lock;
+	int			alarm_irq;
+	bool			alarm_clk_enabled;
+};
+

[...]

+static int pic32_rtc_gettime(struct device *dev, struct rtc_time *rtc_tm)
+{
+	struct pic32_rtc_dev *pdata = dev_get_drvdata(dev);
+	void __iomem *base = pdata->reg_base;
+	unsigned int have_retried = 0;
+
+	clk_enable(pdata->clk);
+retry_get_time:
+	rtc_tm->tm_hour = readb(base + PIC32_RTCHOUR);
+	rtc_tm->tm_min = readb(base + PIC32_RTCMIN);
+	rtc_tm->tm_mon  = readb(base + PIC32_RTCMON);
+	rtc_tm->tm_mday = readb(base + PIC32_RTCDAY);
+	rtc_tm->tm_year = readb(base + PIC32_RTCYEAR);
+	rtc_tm->tm_sec  = readb(base + PIC32_RTCSEC);
+
+	/*
+	 * The only way to work out whether the system was mid-update
+	 * when we read it is to check the second counter, and if it
+	 * is zero, then we re-try the entire read.
+	 */
+
+	if (rtc_tm->tm_sec == 0 && !have_retried) {
+		have_retried = 1;
+		goto retry_get_time;
+	}

Please change that goto in a do while loop.

+
+	rtc_tm->tm_sec = bcd2bin(rtc_tm->tm_sec);
+	rtc_tm->tm_min = bcd2bin(rtc_tm->tm_min);
+	rtc_tm->tm_hour = bcd2bin(rtc_tm->tm_hour);
+	rtc_tm->tm_mday = bcd2bin(rtc_tm->tm_mday);
+	rtc_tm->tm_mon = bcd2bin(rtc_tm->tm_mon);
+	rtc_tm->tm_year = bcd2bin(rtc_tm->tm_year);
+
+	rtc_tm->tm_year += 100;
+
+	dev_dbg(dev, "read time %04d.%02d.%02d %02d:%02d:%02d\n",
+		1900 + rtc_tm->tm_year, rtc_tm->tm_mon, rtc_tm->tm_mday,
+		rtc_tm->tm_hour, rtc_tm->tm_min, rtc_tm->tm_sec);
+
+	rtc_tm->tm_mon -= 1;

Maybe you should do that substraction with the assignment the only
drawback is that it changes the debug output.

+
+	clk_disable(pdata->clk);
+	return rtc_valid_tm(rtc_tm);
+}
+

[...]

+static int pic32_rtc_getalarm(struct device *dev, struct rtc_wkalrm *alrm)
+{
+	struct pic32_rtc_dev *pdata = dev_get_drvdata(dev);
+	struct rtc_time *alm_tm = &alrm->time;
+	void __iomem *base = pdata->reg_base;
+	unsigned int alm_en;
+
+	clk_enable(pdata->clk);
+	alm_tm->tm_sec  = readb(base + PIC32_ALRMSEC);
+	alm_tm->tm_min  = readb(base + PIC32_ALRMMIN);
+	alm_tm->tm_hour = readb(base + PIC32_ALRMHOUR);
+	alm_tm->tm_mon  = readb(base + PIC32_ALRMMON);
+	alm_tm->tm_mday = readb(base + PIC32_ALRMDAY);
+	alm_tm->tm_year = readb(base + PIC32_ALRMYEAR);
+
+	alm_en = readb(base + PIC32_RTCALRM);
+
+	alrm->enabled = (alm_en & PIC32_RTCALRM_ALRMEN) ? 1 : 0;
+
+	dev_dbg(dev, "getalarm: %d, %04d.%02d.%02d %02d:%02d:%02d\n",
+		alm_en,
+		1900 + alm_tm->tm_year, alm_tm->tm_mon, alm_tm->tm_mday,
+		alm_tm->tm_hour, alm_tm->tm_min, alm_tm->tm_sec);
+
+	alm_tm->tm_sec = bcd2bin(alm_tm->tm_sec);
+	alm_tm->tm_min = bcd2bin(alm_tm->tm_min);
+	alm_tm->tm_hour = bcd2bin(alm_tm->tm_hour);
+	alm_tm->tm_mday = bcd2bin(alm_tm->tm_mday);
+	alm_tm->tm_mon = bcd2bin(alm_tm->tm_mon);
+	alm_tm->tm_mon -= 1;

You could merge both lines.

+	alm_tm->tm_year = bcd2bin(alm_tm->tm_year);
+
+	clk_disable(pdata->clk);
+	return 0;
+}
+
+static int pic32_rtc_setalarm(struct device *dev, struct rtc_wkalrm *alrm)
+{
+	struct pic32_rtc_dev *pdata = dev_get_drvdata(dev);
+	struct rtc_time *tm = &alrm->time;
+	void __iomem *base = pdata->reg_base;
+
+	clk_enable(pdata->clk);
+	dev_dbg(dev, "setalarm: %d, %04d.%02d.%02d %02d:%02d:%02d\n",
+		alrm->enabled,
+		1900 + tm->tm_year, tm->tm_mon + 1, tm->tm_mday,
+		tm->tm_hour, tm->tm_min, tm->tm_sec);
+
+	writel(0x00, base + PIC32_ALRMTIME);
+	writel(0x00, base + PIC32_ALRMDATE);
+
+	if (tm->tm_sec < 60 && tm->tm_sec >= 0)
+		writeb(bin2bcd(tm->tm_sec), base + PIC32_ALRMSEC);
+
+	if (tm->tm_min < 60 && tm->tm_min >= 0)
+		writeb(bin2bcd(tm->tm_min), base + PIC32_ALRMMIN);
+
+	if (tm->tm_hour < 24 && tm->tm_hour >= 0)
+		writeb(bin2bcd(tm->tm_hour), base + PIC32_ALRMHOUR);
+

Those three tests are unnecessary because rtc_valid_tm() is called
before ops->set_alarm.

+	pic32_rtc_setaie(dev, alrm->enabled);
+
+	clk_disable(pdata->clk);
+	return 0;
+}
+

[...]

+	pic32_rtc_gettime(&pdev->dev, &rtc_tm);
+
+	if (rtc_valid_tm(&rtc_tm)) {
+		rtc_tm.tm_year	= 100;
+		rtc_tm.tm_mon	= 0;
+		rtc_tm.tm_mday	= 1;
+		rtc_tm.tm_hour	= 0;
+		rtc_tm.tm_min	= 0;
+		rtc_tm.tm_sec	= 0;
+
+		pic32_rtc_settime(NULL, &rtc_tm);
+
+		dev_warn(&pdev->dev,
+			"warning: invalid RTC value so initializing it\n");

This is a bad idea. If you do that, userspace has no way of knowing
whether the date is valid or not.

[...]

+static const struct of_device_id pic32_rtc_dt_ids[] = {
+	{ .compatible = "microchip,pic32mzda-rtc" },
+	{ /* sentinel */ }
+};
+MODULE_DEVICE_TABLE(of, pic32_rtc_dt_ids);

This compatible string needs to be documented. Was that patch 1/2?

+
+static struct platform_driver pic32_rtc_driver = {
+	.probe		= pic32_rtc_probe,
+	.remove		= pic32_rtc_remove,
+	.driver		= {
+		.name	= DRIVER_NAME,
+		.owner	= THIS_MODULE,
+		.of_match_table	= of_match_ptr(pic32_rtc_dt_ids),
+	},
+};
+module_platform_driver(pic32_rtc_driver);
+
+MODULE_DESCRIPTION("Microchip PIC32 RTC Driver");
+MODULE_AUTHOR("Joshua Henderson [off-list ref]");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS("platform:" DRIVER_NAME);

I think this driver is DT only, you can get rid of MODULE_ALIAS and
DRIVER_NAME


-- 
Alexandre Belloni, Free Electrons
Embedded Linux, Kernel and Android engineering
http://free-electrons.com

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