[PATCH v2 0/2] rtc: Add a driver for Cadence RTC

[PATCH v2 0/2] rtc: Add a driver for Cadence RTC

[Jan Kotas]

This patchset adds a driver support for Cadence RTC IP.
It supports time, date and wakeups from sleep.

Changes since v1:
	Added devm_rtc_allocate_device before requesting an IRQ
	Added range_min, range_max values
	Return -EINVAL for read_time() if RTC is disabled
	Fixed some typos

Jan Kotas (2):
  dt-bindings: rtc: Add bindings for Cadence RTC
  rtc: Add Cadence RTC driver

 Documentation/devicetree/bindings/rtc/cdns,rtc.txt |  25 ++
 drivers/rtc/Kconfig                                |  10 +
 drivers/rtc/Makefile                               |   1 +
 drivers/rtc/rtc-cadence.c                          | 423 +++++++++++++++++++++
 4 files changed, 459 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/rtc/cdns,rtc.txt
 create mode 100644 drivers/rtc/rtc-cadence.c

-- 
2.15.0

[PATCH v2 1/2] dt-bindings: rtc: Add bindings for Cadence RTC

[Jan Kotas]

This patch adds a DT binding documentation for
Cadence RTC controller.

Signed-off-by: Jan Kotas <jank@cadence.com>
---
 Documentation/devicetree/bindings/rtc/cdns,rtc.txt | 25 ++++++++++++++++++++++
 1 file changed, 25 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/rtc/cdns,rtc.txt

diff --git a/Documentation/devicetree/bindings/rtc/cdns,rtc.txt b/Documentation/devicetree/bindings/rtc/cdns,rtc.txt
new file mode 100644
index 000000000..40713bbbe
--- /dev/null
+++ b/Documentation/devicetree/bindings/rtc/cdns,rtc.txt
@@ -0,0 +1,25 @@
+Cadence Real Time Clock
+
+The Cadence RTC controller with date, time and alarm capabilities.
+The alarm may wake the system from low-power state.
+
+Required properties:
+- compatible: Should be "cdns,rtc-r109v3"
+- reg: Specifies base physical address and size of the register area.
+- interrupts: A single interrupt specifier.
+- clocks: Must contain two entries:
+	- pclk: APB registers clock
+	- ref_clk: reference 1Hz of 100Hz clock, depending on IP configuration
+	See ../clocks/clock-bindings.txt for details.
+
+Example:
+        rtc0: rtc@fd080000 {
+        	compatible = "cdns,rtc-r109v3";
+        	reg = <0xfd080000 0x1000>;
+
+        	clock-names = "pclk", "ref_clk";
+        	clocks = <&sysclock>, <&refclock>;
+
+        	interrupt-parent = <&gic>;
+        	interrupts = <0 6 IRQ_TYPE_LEVEL_HIGH>;
+        };
-- 
2.15.0

[PATCH v2 2/2] rtc: Add Cadence RTC driver

[Jan Kotas]

This patch adds a driver for Cadence RTC controller.

It can be enabled with RTC_DRV_CADENCE Kconfig option.
It supports waking system from sleep modes.

Signed-off-by: Jan Kotas <jank@cadence.com>
---
 drivers/rtc/Kconfig       |  10 ++
 drivers/rtc/Makefile      |   1 +
 drivers/rtc/rtc-cadence.c | 423 ++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 434 insertions(+)
 create mode 100644 drivers/rtc/rtc-cadence.c

diff --git a/drivers/rtc/Kconfig b/drivers/rtc/Kconfig
index 225b0b851..0aba341ad 100644
--- a/drivers/rtc/Kconfig
+++ b/drivers/rtc/Kconfig
@@ -1508,6 +1508,16 @@ config RTC_DRV_ARMADA38X
 	  This driver can also be built as a module. If so, the module
 	  will be called armada38x-rtc.
 
+config RTC_DRV_CADENCE
+	tristate "Cadence RTC driver"
+	depends on OF && HAS_IOMEM
+	help
+	  If you say Y here you will get access to Cadence RTC IP
+	  found on certain SOCs.
+
+	  To compile this driver as a module, choose M here: the
+	  module will be called rtc-cadence.
+
 config RTC_DRV_FTRTC010
 	tristate "Faraday Technology FTRTC010 RTC"
 	depends on HAS_IOMEM
diff --git a/drivers/rtc/Makefile b/drivers/rtc/Makefile
index df022d820..5adb41b45 100644
--- a/drivers/rtc/Makefile
+++ b/drivers/rtc/Makefile
@@ -39,6 +39,7 @@ obj-$(CONFIG_RTC_DRV_AU1XXX)	+= rtc-au1xxx.o
 obj-$(CONFIG_RTC_DRV_BQ32K)	+= rtc-bq32k.o
 obj-$(CONFIG_RTC_DRV_BQ4802)	+= rtc-bq4802.o
 obj-$(CONFIG_RTC_DRV_BRCMSTB)	+= rtc-brcmstb-waketimer.o
+obj-$(CONFIG_RTC_DRV_CADENCE)	+= rtc-cadence.o
 obj-$(CONFIG_RTC_DRV_CMOS)	+= rtc-cmos.o
 obj-$(CONFIG_RTC_DRV_COH901331)	+= rtc-coh901331.o
 obj-$(CONFIG_RTC_DRV_CPCAP)	+= rtc-cpcap.o
diff --git a/drivers/rtc/rtc-cadence.c b/drivers/rtc/rtc-cadence.c
new file mode 100644
index 000000000..3b7d643c8
--- /dev/null
+++ b/drivers/rtc/rtc-cadence.c
@@ -0,0 +1,423 @@
+// SPDX-License-Identifier: GPL-2.0
+
+/*
+ * Copyright 2019 Cadence
+ *
+ * Authors:
+ *  Jan Kotas <jank@cadence.com>
+ */
+
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/of.h>
+#include <linux/io.h>
+#include <linux/rtc.h>
+#include <linux/clk.h>
+#include <linux/bcd.h>
+#include <linux/bitfield.h>
+#include <linux/interrupt.h>
+#include <linux/pm_wakeirq.h>
+
+/* Registers */
+#define CDNS_RTC_CTLR		0x00
+#define CDNS_RTC_HMR		0x04
+#define CDNS_RTC_TIMR		0x08
+#define CDNS_RTC_CALR		0x0C
+#define CDNS_RTC_TIMAR		0x10
+#define CDNS_RTC_CALAR		0x14
+#define CDNS_RTC_AENR		0x18
+#define CDNS_RTC_EFLR		0x1C
+#define CDNS_RTC_IENR		0x20
+#define CDNS_RTC_IDISR		0x24
+#define CDNS_RTC_IMSKR		0x28
+#define CDNS_RTC_STSR		0x2C
+#define CDNS_RTC_KRTCR		0x30
+
+/* Control */
+#define CDNS_RTC_CTLR_TIME	BIT(0)
+#define CDNS_RTC_CTLR_CAL	BIT(1)
+#define CDNS_RTC_CTLR_TIME_CAL	(CDNS_RTC_CTLR_TIME | CDNS_RTC_CTLR_CAL)
+
+/* Status */
+#define CDNS_RTC_STSR_VT	BIT(0)
+#define CDNS_RTC_STSR_VC	BIT(1)
+#define CDNS_RTC_STSR_VTA	BIT(2)
+#define CDNS_RTC_STSR_VCA	BIT(3)
+#define CDNS_RTC_STSR_VT_VC	(CDNS_RTC_STSR_VT | CDNS_RTC_STSR_VC)
+#define CDNS_RTC_STSR_VTA_VCA	(CDNS_RTC_STSR_VTA | CDNS_RTC_STSR_VCA)
+
+/* Keep RTC */
+#define CDNS_RTC_KRTCR_KRTC	BIT(0)
+
+/* Alarm, Event, Interrupt */
+#define CDNS_RTC_AEI_HOS	BIT(0)
+#define CDNS_RTC_AEI_SEC	BIT(1)
+#define CDNS_RTC_AEI_MIN	BIT(2)
+#define CDNS_RTC_AEI_HOUR	BIT(3)
+#define CDNS_RTC_AEI_DATE	BIT(4)
+#define CDNS_RTC_AEI_MNTH	BIT(5)
+#define CDNS_RTC_AEI_ALRM	BIT(6)
+
+/* Time */
+#define CDNS_RTC_TIME_H		GENMASK(7, 0)
+#define CDNS_RTC_TIME_S		GENMASK(14, 8)
+#define CDNS_RTC_TIME_M		GENMASK(22, 16)
+#define CDNS_RTC_TIME_HR	GENMASK(29, 24)
+#define CDNS_RTC_TIME_PM	BIT(30)
+#define CDNS_RTC_TIME_CH	BIT(31)
+
+/* Calendar */
+#define CDNS_RTC_CAL_DAY	GENMASK(2, 0)
+#define CDNS_RTC_CAL_M		GENMASK(7, 3)
+#define CDNS_RTC_CAL_D		GENMASK(13, 8)
+#define CDNS_RTC_CAL_Y		GENMASK(23, 16)
+#define CDNS_RTC_CAL_C		GENMASK(29, 24)
+#define CDNS_RTC_CAL_CH		BIT(31)
+
+#define CDNS_RTC_MAX_REGS_TRIES	3
+
+struct cdns_rtc {
+	struct rtc_device *rtc_dev;
+	struct clk *pclk;
+	struct clk *ref_clk;
+	void __iomem *regs;
+	int irq;
+};
+
+static void cdns_rtc_set_enabled(struct cdns_rtc *crtc, bool enabled)
+{
+	u32 reg = enabled ? 0x0 : CDNS_RTC_CTLR_TIME_CAL;
+
+	writel(reg, crtc->regs + CDNS_RTC_CTLR);
+}
+
+static bool cdns_rtc_get_enabled(struct cdns_rtc *crtc)
+{
+	return !(readl(crtc->regs + CDNS_RTC_CTLR) & CDNS_RTC_CTLR_TIME_CAL);
+}
+
+static irqreturn_t cdns_rtc_irq_handler(int irq, void *id)
+{
+	struct device *dev = id;
+	struct cdns_rtc *crtc = dev_get_drvdata(dev);
+
+	/* Reading the register clears it */
+	if (!(readl(crtc->regs + CDNS_RTC_EFLR) & CDNS_RTC_AEI_ALRM))
+		return IRQ_NONE;
+
+	rtc_update_irq(crtc->rtc_dev, 1, RTC_IRQF | RTC_AF);
+	return IRQ_HANDLED;
+}
+
+static u32 cdns_rtc_time2reg(struct rtc_time *tm)
+{
+	return FIELD_PREP(CDNS_RTC_TIME_S,  bin2bcd(tm->tm_sec))
+	     | FIELD_PREP(CDNS_RTC_TIME_M,  bin2bcd(tm->tm_min))
+	     | FIELD_PREP(CDNS_RTC_TIME_HR, bin2bcd(tm->tm_hour));
+}
+
+static void cdns_rtc_reg2time(u32 reg, struct rtc_time *tm)
+{
+	tm->tm_sec  = bcd2bin(FIELD_GET(CDNS_RTC_TIME_S, reg));
+	tm->tm_min  = bcd2bin(FIELD_GET(CDNS_RTC_TIME_M, reg));
+	tm->tm_hour = bcd2bin(FIELD_GET(CDNS_RTC_TIME_HR, reg));
+}
+
+static int cdns_rtc_read_time(struct device *dev, struct rtc_time *tm)
+{
+	struct cdns_rtc *crtc = dev_get_drvdata(dev);
+	u32 reg;
+
+	/* If the RTC is disabled, assume the values are invalid */
+	if (!cdns_rtc_get_enabled(crtc))
+		return -EINVAL;
+
+	cdns_rtc_set_enabled(crtc, false);
+
+	reg = readl(crtc->regs + CDNS_RTC_TIMR);
+	cdns_rtc_reg2time(reg, tm);
+
+	reg = readl(crtc->regs + CDNS_RTC_CALR);
+	tm->tm_mday = bcd2bin(FIELD_GET(CDNS_RTC_CAL_D, reg));
+	tm->tm_mon  = bcd2bin(FIELD_GET(CDNS_RTC_CAL_M, reg)) - 1;
+	tm->tm_year = bcd2bin(FIELD_GET(CDNS_RTC_CAL_Y, reg))
+		    + bcd2bin(FIELD_GET(CDNS_RTC_CAL_C, reg)) * 100 - 1900;
+	tm->tm_wday = bcd2bin(FIELD_GET(CDNS_RTC_CAL_DAY, reg)) - 1;
+
+	cdns_rtc_set_enabled(crtc, true);
+	return 0;
+}
+
+static int cdns_rtc_set_time(struct device *dev, struct rtc_time *tm)
+{
+	struct cdns_rtc *crtc = dev_get_drvdata(dev);
+	u32 timr, calr, stsr;
+	int ret = -EIO;
+	int year = tm->tm_year + 1900;
+	int tries;
+
+	cdns_rtc_set_enabled(crtc, false);
+
+	timr = cdns_rtc_time2reg(tm);
+
+	calr = FIELD_PREP(CDNS_RTC_CAL_D, bin2bcd(tm->tm_mday))
+	     | FIELD_PREP(CDNS_RTC_CAL_M, bin2bcd(tm->tm_mon + 1))
+	     | FIELD_PREP(CDNS_RTC_CAL_Y, bin2bcd(year % 100))
+	     | FIELD_PREP(CDNS_RTC_CAL_C, bin2bcd(year / 100))
+	     | FIELD_PREP(CDNS_RTC_CAL_DAY, tm->tm_wday + 1);
+
+	/* Update registers, check valid flags */
+	for (tries = 0; tries < CDNS_RTC_MAX_REGS_TRIES; tries++) {
+		writel(timr, crtc->regs + CDNS_RTC_TIMR);
+		writel(calr, crtc->regs + CDNS_RTC_CALR);
+		stsr = readl(crtc->regs + CDNS_RTC_STSR);
+
+		if ((stsr & CDNS_RTC_STSR_VT_VC) == CDNS_RTC_STSR_VT_VC) {
+			ret = 0;
+			break;
+		}
+	}
+
+	cdns_rtc_set_enabled(crtc, true);
+	return ret;
+}
+
+static int cdns_rtc_alarm_irq_enable(struct device *dev, unsigned int enabled)
+{
+	struct cdns_rtc *crtc = dev_get_drvdata(dev);
+
+	if (enabled) {
+		writel((CDNS_RTC_AEI_SEC | CDNS_RTC_AEI_MIN | CDNS_RTC_AEI_HOUR
+			| CDNS_RTC_AEI_DATE | CDNS_RTC_AEI_MNTH),
+		       crtc->regs + CDNS_RTC_AENR);
+		writel(CDNS_RTC_AEI_ALRM, crtc->regs + CDNS_RTC_IENR);
+	} else {
+		writel(0, crtc->regs + CDNS_RTC_AENR);
+		writel(CDNS_RTC_AEI_ALRM, crtc->regs + CDNS_RTC_IDISR);
+	}
+
+	return 0;
+}
+
+static int cdns_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alarm)
+{
+	struct cdns_rtc *crtc = dev_get_drvdata(dev);
+	u32 reg;
+
+	reg = readl(crtc->regs + CDNS_RTC_TIMAR);
+	cdns_rtc_reg2time(reg, &alarm->time);
+
+	reg = readl(crtc->regs + CDNS_RTC_CALAR);
+	alarm->time.tm_mday = bcd2bin(FIELD_GET(CDNS_RTC_CAL_D, reg));
+	alarm->time.tm_mon  = bcd2bin(FIELD_GET(CDNS_RTC_CAL_M, reg)) - 1;
+
+	return 0;
+}
+
+static int cdns_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alarm)
+{
+	struct cdns_rtc *crtc = dev_get_drvdata(dev);
+	int ret = -EIO;
+	int tries;
+	u32 timar, calar, stsr;
+
+	cdns_rtc_alarm_irq_enable(dev, 0);
+
+	timar = cdns_rtc_time2reg(&alarm->time);
+	calar = FIELD_PREP(CDNS_RTC_CAL_D, bin2bcd(alarm->time.tm_mday))
+	      | FIELD_PREP(CDNS_RTC_CAL_M, bin2bcd(alarm->time.tm_mon + 1));
+
+	/* Update registers, check valid alarm flags */
+	for (tries = 0; tries < CDNS_RTC_MAX_REGS_TRIES; tries++) {
+		writel(timar, crtc->regs + CDNS_RTC_TIMAR);
+		writel(calar, crtc->regs + CDNS_RTC_CALAR);
+		stsr = readl(crtc->regs + CDNS_RTC_STSR);
+
+		if ((stsr & CDNS_RTC_STSR_VTA_VCA) == CDNS_RTC_STSR_VTA_VCA) {
+			ret = 0;
+			break;
+		}
+	}
+
+	if (!ret)
+		cdns_rtc_alarm_irq_enable(dev, alarm->enabled);
+	return ret;
+}
+
+static const struct rtc_class_ops cdns_rtc_ops = {
+	.read_time	= cdns_rtc_read_time,
+	.set_time	= cdns_rtc_set_time,
+	.read_alarm	= cdns_rtc_read_alarm,
+	.set_alarm	= cdns_rtc_set_alarm,
+	.alarm_irq_enable = cdns_rtc_alarm_irq_enable,
+};
+
+static int cdns_rtc_probe(struct platform_device *pdev)
+{
+	struct cdns_rtc *crtc;
+	struct resource *res;
+	int ret;
+	unsigned long ref_clk_freq;
+
+	crtc = devm_kzalloc(&pdev->dev, sizeof(*crtc), GFP_KERNEL);
+	if (!crtc)
+		return -ENOMEM;
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	crtc->regs = devm_ioremap_resource(&pdev->dev, res);
+	if (IS_ERR(crtc->regs))
+		return PTR_ERR(crtc->regs);
+
+	crtc->irq = platform_get_irq(pdev, 0);
+	if (crtc->irq < 0)
+		return -EINVAL;
+
+	crtc->pclk = devm_clk_get(&pdev->dev, "pclk");
+	if (IS_ERR(crtc->pclk)) {
+		ret = PTR_ERR(crtc->pclk);
+		dev_err(&pdev->dev,
+			"Failed to retrieve the peripheral clock, %d\n", ret);
+		return ret;
+	}
+
+	crtc->ref_clk = devm_clk_get(&pdev->dev, "ref_clk");
+	if (IS_ERR(crtc->ref_clk)) {
+		ret = PTR_ERR(crtc->ref_clk);
+		dev_err(&pdev->dev,
+			"Failed to retrieve the reference clock, %d\n", ret);
+		return ret;
+	}
+
+	crtc->rtc_dev = devm_rtc_allocate_device(&pdev->dev);
+	if (IS_ERR(crtc->rtc_dev)) {
+		ret = PTR_ERR(crtc->rtc_dev);
+		dev_err(&pdev->dev,
+			"Failed to allocate the RTC device, %d\n", ret);
+		return ret;
+	}
+
+	platform_set_drvdata(pdev, crtc);
+
+	ret = clk_prepare_enable(crtc->pclk);
+	if (ret) {
+		dev_err(&pdev->dev,
+			"Failed to enable the peripheral clock, %d\n", ret);
+		return ret;
+	}
+
+	ret = clk_prepare_enable(crtc->ref_clk);
+	if (ret) {
+		dev_err(&pdev->dev,
+			"Failed to enable the reference clock, %d\n", ret);
+		goto err_disable_pclk;
+	}
+
+	ref_clk_freq = clk_get_rate(crtc->ref_clk);
+	if ((ref_clk_freq != 1) && (ref_clk_freq != 100)) {
+		dev_err(&pdev->dev,
+			"Invalid reference clock frequency %lu Hz.\n",
+			ref_clk_freq);
+		ret = -EINVAL;
+		goto err_disable_ref_clk;
+	}
+
+	ret = devm_request_irq(&pdev->dev, crtc->irq,
+			       cdns_rtc_irq_handler, 0,
+			       dev_name(&pdev->dev), &pdev->dev);
+	if (ret) {
+		dev_err(&pdev->dev,
+			"Failed to request interrupt for the device, %d\n",
+			ret);
+		goto err_disable_ref_clk;
+	}
+
+	/* The RTC supports 01.01.1900 - 31.12.2999 */
+	crtc->rtc_dev->range_min = mktime64(1900,  1,  1,  0,  0,  0);
+	crtc->rtc_dev->range_max = mktime64(2999, 12, 31, 23, 59, 59);
+
+	crtc->rtc_dev->ops = &cdns_rtc_ops;
+	device_init_wakeup(&pdev->dev, true);
+
+	/* Always use 24-hour mode and keep the RTC values */
+	writel(0, crtc->regs + CDNS_RTC_HMR);
+	writel(CDNS_RTC_KRTCR_KRTC, crtc->regs + CDNS_RTC_KRTCR);
+
+	ret = rtc_register_device(crtc->rtc_dev);
+	if (ret) {
+		dev_err(&pdev->dev,
+			"Failed to register the RTC device, %d\n", ret);
+		goto err_disable_wakeup;
+	}
+
+	return 0;
+
+err_disable_wakeup:
+	device_init_wakeup(&pdev->dev, false);
+
+err_disable_ref_clk:
+	clk_disable_unprepare(crtc->ref_clk);
+
+err_disable_pclk:
+	clk_disable_unprepare(crtc->pclk);
+
+	return ret;
+}
+
+static int cdns_rtc_remove(struct platform_device *pdev)
+{
+	struct cdns_rtc *crtc = platform_get_drvdata(pdev);
+
+	cdns_rtc_alarm_irq_enable(&pdev->dev, 0);
+	device_init_wakeup(&pdev->dev, 0);
+
+	clk_disable_unprepare(crtc->pclk);
+	clk_disable_unprepare(crtc->ref_clk);
+
+	return 0;
+}
+
+#ifdef CONFIG_PM_SLEEP
+static int cdns_rtc_suspend(struct device *dev)
+{
+	struct cdns_rtc *crtc = dev_get_drvdata(dev);
+
+	if (device_may_wakeup(dev))
+		enable_irq_wake(crtc->irq);
+
+	return 0;
+}
+
+static int cdns_rtc_resume(struct device *dev)
+{
+	struct cdns_rtc *crtc = dev_get_drvdata(dev);
+
+	if (device_may_wakeup(dev))
+		disable_irq_wake(crtc->irq);
+
+	return 0;
+}
+#endif
+
+static SIMPLE_DEV_PM_OPS(cdns_rtc_pm_ops, cdns_rtc_suspend, cdns_rtc_resume);
+
+static const struct of_device_id cdns_rtc_of_match[] = {
+	{ .compatible = "cdns,rtc-r109v3" },
+	{ },
+};
+MODULE_DEVICE_TABLE(of, cdns_rtc_of_match);
+
+static struct platform_driver cdns_rtc_driver = {
+	.driver = {
+		.name = "cdns-rtc",
+		.of_match_table = cdns_rtc_of_match,
+		.pm = &cdns_rtc_pm_ops,
+	},
+	.probe = cdns_rtc_probe,
+	.remove = cdns_rtc_remove,
+};
+module_platform_driver(cdns_rtc_driver);
+
+MODULE_AUTHOR("Jan Kotas <jank@cadence.com>");
+MODULE_DESCRIPTION("Cadence RTC driver");
+MODULE_LICENSE("GPL v2");
+MODULE_ALIAS("platform:cdns-rtc");
-- 
2.15.0

Re: [PATCH v2 1/2] dt-bindings: rtc: Add bindings for Cadence RTC

[Rob Herring]

On Fri, Jan 11, 2019 at 03:14:00PM +0000, Jan Kotas wrote:
> This patch adds a DT binding documentation for
> Cadence RTC controller.
> 
> Signed-off-by: Jan Kotas <jank@cadence.com>
> ---
>  Documentation/devicetree/bindings/rtc/cdns,rtc.txt | 25 ++++++++++++++++++++++
>  1 file changed, 25 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/rtc/cdns,rtc.txt
> 
> diff --git a/Documentation/devicetree/bindings/rtc/cdns,rtc.txt b/Documentation/devicetree/bindings/rtc/cdns,rtc.txt
> new file mode 100644
> index 000000000..40713bbbe
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/rtc/cdns,rtc.txt
> @@ -0,0 +1,25 @@
> +Cadence Real Time Clock
> +
> +The Cadence RTC controller with date, time and alarm capabilities.
> +The alarm may wake the system from low-power state.
> +
> +Required properties:
> +- compatible: Should be "cdns,rtc-r109v3"
> +- reg: Specifies base physical address and size of the register area.
> +- interrupts: A single interrupt specifier.
> +- clocks: Must contain two entries:
> +	- pclk: APB registers clock
> +	- ref_clk: reference 1Hz of 100Hz clock, depending on IP configuration

1Hz OR 100Hz?

> +	See ../clocks/clock-bindings.txt for details.
> +
> +Example:
> +        rtc0: rtc@fd080000 {
> +        	compatible = "cdns,rtc-r109v3";
> +        	reg = <0xfd080000 0x1000>;
> +
> +        	clock-names = "pclk", "ref_clk";
> +        	clocks = <&sysclock>, <&refclock>;
> +
> +        	interrupt-parent = <&gic>;
> +        	interrupts = <0 6 IRQ_TYPE_LEVEL_HIGH>;
> +        };
> -- 
> 2.15.0
> 

Re: [PATCH v2 1/2] dt-bindings: rtc: Add bindings for Cadence RTC

[Jan Kotas]

> On 16 Jan 2019, at 22:08, Rob Herring <robh@kernel.org> wrote:
> 
> 
> On Fri, Jan 11, 2019 at 03:14:00PM +0000, Jan Kotas wrote:
>> This patch adds a DT binding documentation for
>> Cadence RTC controller.
>> +Required properties:
>> +- compatible: Should be "cdns,rtc-r109v3"
>> +- reg: Specifies base physical address and size of the register area.
>> +- interrupts: A single interrupt specifier.
>> +- clocks: Must contain two entries:
>> +	- pclk: APB registers clock
>> +	- ref_clk: reference 1Hz of 100Hz clock, depending on IP configuration
> 
> 1Hz OR 100Hz?

Hi,

The IP has a configuration parameter at build time,
which selects the reference clock frequency.

It cannot be changed later, and there’s no register which
tells the software which option was selected.

In this version of the patch, both values are accepted.
If it makes sense I can add a bool property, like
refclock-100hz, which can be used to check the clock frequency.

Regards,
Jan

Re: [PATCH v2 1/2] dt-bindings: rtc: Add bindings for Cadence RTC

[Alexandre Belloni]

On 17/01/2019 10:46:50+0000, Jan Kotas wrote:
> 
> > On 16 Jan 2019, at 22:08, Rob Herring <robh@kernel.org> wrote:
> > 
> > 
> > On Fri, Jan 11, 2019 at 03:14:00PM +0000, Jan Kotas wrote:
> >> This patch adds a DT binding documentation for
> >> Cadence RTC controller.
> >> +Required properties:
> >> +- compatible: Should be "cdns,rtc-r109v3"
> >> +- reg: Specifies base physical address and size of the register area.
> >> +- interrupts: A single interrupt specifier.
> >> +- clocks: Must contain two entries:
> >> +	- pclk: APB registers clock
> >> +	- ref_clk: reference 1Hz of 100Hz clock, depending on IP configuration
> > 
> > 1Hz OR 100Hz?
> 
> Hi,
> 
> The IP has a configuration parameter at build time,
> which selects the reference clock frequency.
> 
> It cannot be changed later, and there’s no register which
> tells the software which option was selected.
> 
> In this version of the patch, both values are accepted.
> If it makes sense I can add a bool property, like
> refclock-100hz, which can be used to check the clock frequency.
> 

I guess what rob suggested was s/of/or/


-- 
Alexandre Belloni, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com