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

[PATCH 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.

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                          | 404 +++++++++++++++++++++
 4 files changed, 440 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/rtc/cdns,rtc.txt
 create mode 100644 drivers/rtc/rtc-cadence.c

-- 
2.15.0

[PATCH 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 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 | 404 ++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 415 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..18fc3f8e3
--- /dev/null
+++ b/drivers/rtc/rtc-cadence.c
@@ -0,0 +1,404 @@
+// 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 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;
+
+	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_SEC),
+		       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;
+	}
+
+	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,
+			"Unable to request interrupt for the device, %d\n",
+			ret);
+		goto err_disable_ref_clk;
+	}
+
+	/* Always use 24-hour mode */
+	writel(0, crtc->regs + CDNS_RTC_HMR);
+
+	device_init_wakeup(&pdev->dev, 1);
+	platform_set_drvdata(pdev, crtc);
+	cdns_rtc_set_enabled(crtc, true);
+
+	crtc->rtc_dev = devm_rtc_device_register(&pdev->dev,
+						 dev_name(&pdev->dev),
+						 &cdns_rtc_ops,
+						 THIS_MODULE);
+	if (IS_ERR(crtc->rtc_dev)) {
+		ret = PTR_ERR(crtc->rtc_dev);
+		dev_err(&pdev->dev, "Unable to register the rtc device, %d\n",
+			ret);
+		goto err_stop_rtc;
+	}
+
+	return 0;
+
+err_stop_rtc:
+	cdns_rtc_set_enabled(crtc, 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 2/2] rtc: Add Cadence RTC driver

[Alexandre Belloni]

Hello,

On 08/01/2019 12:22:42+0000, Jan Kotas wrote:
>  drivers/rtc/Kconfig       |  10 ++
>  drivers/rtc/Makefile      |   1 +
>  drivers/rtc/rtc-cadence.c | 404 ++++++++++++++++++++++++++++++++++++++++++++++

I would prefer a name that is a bit less generic, unless you can
guarantee this driver will be able to handle every RTCs from Cadence.

> +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_SEC),

CDNS_RTC_AEI_SEC is used twice here.

> +		       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_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;
> +	}
> +
> +	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,
> +			"Unable to request interrupt for the device, %d\n",
> +			ret);
> +		goto err_disable_ref_clk;
> +	}
> +

You should use devm_rtc_allocate_device to allocate crtc->rtc_dev before
requesting the IRQ. Else, this leaves a race condition open.

Also, please set crtc->rtc_dev->range_min and crtc->rtc_dev->range_max
according to the fully contiguous range of time that is supported by the
RTC. You can use
https://git.kernel.org/pub/scm/linux/kernel/git/abelloni/rtc-tools.git/tree/rtc-range.c
to assist you.

> +	/* Always use 24-hour mode */
> +	writel(0, crtc->regs + CDNS_RTC_HMR);
> +
> +	device_init_wakeup(&pdev->dev, 1);
> +	platform_set_drvdata(pdev, crtc);
> +	cdns_rtc_set_enabled(crtc, true);

Is that really necessary? I guess you could check whether it has already
been enabled to know whether the currently set time is valid so
cdns_rtc_read_time could return -EINVAL when it knows it isn't valid.
cdns_rtc_set_time will enable the RTC once the time has been set anyway.

> +
> +	crtc->rtc_dev = devm_rtc_device_register(&pdev->dev,
> +						 dev_name(&pdev->dev),
> +						 &cdns_rtc_ops,
> +						 THIS_MODULE);
> +	if (IS_ERR(crtc->rtc_dev)) {
> +		ret = PTR_ERR(crtc->rtc_dev);
> +		dev_err(&pdev->dev, "Unable to register the rtc device, %d\n",
> +			ret);
> +		goto err_stop_rtc;
> +	}
> +
> +	return 0;
> +
> +err_stop_rtc:
> +	cdns_rtc_set_enabled(crtc, 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" },

Is r109v3 an IP name or a revision?

> +	{ },
> +};
> +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
> 

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

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

[Janek Kotas]

Hi Alexandre,

Thank you for your reply.

> On 10 Jan 2019, at 23:27, Alexandre Belloni <alexandre.belloni@bootlin.com> wrote:
> 
> Hello,
> 
> On 08/01/2019 12:22:42+0000, Jan Kotas wrote:
>> drivers/rtc/Kconfig       |  10 ++
>> drivers/rtc/Makefile      |   1 +
>> drivers/rtc/rtc-cadence.c | 404 ++++++++++++++++++++++++++++++++++++++++++++++
> 
> I would prefer a name that is a bit less generic, unless you can
> guarantee this driver will be able to handle every RTCs from Cadence.

Yes, that’s the only IP that is being sold.
It was designed a long time ago, it’s not being actively developed
in terms of new features.

>> +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_SEC),
> 
> CDNS_RTC_AEI_SEC is used twice here.

Thanks for spotting that, I’ll fix it.

>> 
>> +	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,
>> +			"Unable to request interrupt for the device, %d\n",
>> +			ret);
>> +		goto err_disable_ref_clk;
>> +	}
>> +
> 
> You should use devm_rtc_allocate_device to allocate crtc->rtc_dev before
> requesting the IRQ. Else, this leaves a race condition open.

Ok, I’ll fix it.

> Also, please set crtc->rtc_dev->range_min and crtc->rtc_dev->range_max
> according to the fully contiguous range of time that is supported by the
> RTC. 

I’ll add it, thanks for pointing it out.

>> +	/* Always use 24-hour mode */
>> +	writel(0, crtc->regs + CDNS_RTC_HMR);
>> +
>> +	device_init_wakeup(&pdev->dev, 1);
>> +	platform_set_drvdata(pdev, crtc);
>> +	cdns_rtc_set_enabled(crtc, true);
> 
> Is that really necessary? I guess you could check whether it has already
> been enabled to know whether the currently set time is valid so
> cdns_rtc_read_time could return -EINVAL when it knows it isn't valid.
> cdns_rtc_set_time will enable the RTC once the time has been set anyway.

That’s a good idea, I’ll add it.

>> +static const struct of_device_id cdns_rtc_of_match[] = {
>> +	{ .compatible = "cdns,rtc-r109v3" },
> 
> Is r109v3 an IP name or a revision?

It’s a revision.

> -- 
> Alexandre Belloni, Bootlin
> Embedded Linux and Kernel engineering

Regards,
Jan