[PATCH 0/4] Add a new RTC driver for recent mvebu SoCs

[PATCH 0/4] Add a new RTC driver for recent mvebu SoCs

[Gregory CLEMENT]

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Hi,

The Marvell Armada 38x SoCs contains an RTC which differs from the RTC
used in the other mvebu SoCs until now. This patch set adds support
for this new IP and enable it in the Device Tree of the Armada 38x
SoC.

Thanks,

Grégory

Gregory CLEMENT (4):
  rtc: armada38x: Add the device tree binding documentation
  drivers/rtc/rtc-armada38x: Add a new RTC driver for recent mvebu SoCs
  MAINTAINERS: Add the RTC driver for the Armada38x
  ARM: mvebu: add Device Tree description of RTC on Armada 38x

 .../devicetree/bindings/rtc/armada-380-rtc.txt     |  17 ++
 MAINTAINERS                                        |   1 +
 arch/arm/boot/dts/armada-38x.dtsi                  |   6 +
 drivers/rtc/Kconfig                                |  10 +
 drivers/rtc/Makefile                               |   1 +
 drivers/rtc/rtc-armada38x.c                        | 305 +++++++++++++++++++++
 6 files changed, 340 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/rtc/armada-380-rtc.txt
 create mode 100644 drivers/rtc/rtc-armada38x.c

-- 
1.9.1

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[PATCH 1/4] rtc: armada38x: Add the device tree binding documentation

[Gregory CLEMENT]

The Armada 38x SoCs come with a new RTC which differs from the one
used in the other mvebu SoCs until now. This patch describes the
binding of this RTC.

Signed-off-by: Gregory CLEMENT <gregory.clement-wi1+55ScJUtKEb57/3fJTNBPR1lH4CV8@public.gmane.org>
---
 .../devicetree/bindings/rtc/armada-380-rtc.txt          | 17 +++++++++++++++++
 1 file changed, 17 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/rtc/armada-380-rtc.txt

diff --git a/Documentation/devicetree/bindings/rtc/armada-380-rtc.txt b/Documentation/devicetree/bindings/rtc/armada-380-rtc.txt
new file mode 100644
index 000000000000..2c56bef9dd7e
--- /dev/null
+++ b/Documentation/devicetree/bindings/rtc/armada-380-rtc.txt
@@ -0,0 +1,17 @@
+* Real Time Clock of te Armada 38x SoCs
+
+RTC controller for the Armada 38x SoCs
+
+Required properties:
+- compatible : Should be "marvell,armada-380-rtc"
+- reg: physical base address of the controller and length of memory mapped
+  region. The second entires is for the IP configuration part.
+- interrupts: IRQ line for the RTC.
+
+Example:
+
+rtc@184a8 {
+	compatible = "marvell,armada-380-rtc";
+	reg = <0xa3800 0x20>, <0x184a0 0x0c>;
+	interrupts = <GIC_SPI 21 IRQ_TYPE_LEVEL_HIGH>;
+};
-- 
1.9.1

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[PATCH 2/4] drivers/rtc/rtc-armada38x: Add a new RTC driver for recent mvebu SoCs

[Gregory CLEMENT]

The new mvebu SoCs come with a new RTC driver. This patch adds the
support for this new IP which is currently found in the Armada 38x
SoCs.

This RTC provides two alarms, but only the first one is used in the
driver. The RTC also allows using periodic interrupts.

Signed-off-by: Gregory CLEMENT <gregory.clement-wi1+55ScJUtKEb57/3fJTNBPR1lH4CV8@public.gmane.org>
---
 drivers/rtc/Kconfig         |  10 ++
 drivers/rtc/Makefile        |   1 +
 drivers/rtc/rtc-armada38x.c | 305 ++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 316 insertions(+)
 create mode 100644 drivers/rtc/rtc-armada38x.c

diff --git a/drivers/rtc/Kconfig b/drivers/rtc/Kconfig
index f15cddfeb897..de42ebd4b626 100644
--- a/drivers/rtc/Kconfig
+++ b/drivers/rtc/Kconfig
@@ -1269,6 +1269,16 @@ config RTC_DRV_MV
 	  This driver can also be built as a module. If so, the module
 	  will be called rtc-mv.
 
+config RTC_DRV_ARMADA38X
+	tristate "Armada 38x Marvell SoC RTC"
+	depends on ARCH_MVEBU
+	help
+	  If you say yes here you will get support for the in-chip RTC
+	  that can be found in the Armada 38x Marvell's SoC device
+
+	  This driver can also be built as a module. If so, the module
+	  will be called armada38x-rtc.
+
 config RTC_DRV_PS3
 	tristate "PS3 RTC"
 	depends on PPC_PS3
diff --git a/drivers/rtc/Makefile b/drivers/rtc/Makefile
index c8ef3e1e6ccd..03fe5629c464 100644
--- a/drivers/rtc/Makefile
+++ b/drivers/rtc/Makefile
@@ -24,6 +24,7 @@ obj-$(CONFIG_RTC_DRV_88PM860X)  += rtc-88pm860x.o
 obj-$(CONFIG_RTC_DRV_88PM80X)	+= rtc-88pm80x.o
 obj-$(CONFIG_RTC_DRV_AB3100)	+= rtc-ab3100.o
 obj-$(CONFIG_RTC_DRV_AB8500)	+= rtc-ab8500.o
+obj-$(CONFIG_RTC_DRV_ARMADA38X)	+= rtc-armada38x.o
 obj-$(CONFIG_RTC_DRV_AS3722)	+= rtc-as3722.o
 obj-$(CONFIG_RTC_DRV_AT32AP700X)+= rtc-at32ap700x.o
 obj-$(CONFIG_RTC_DRV_AT91RM9200)+= rtc-at91rm9200.o
diff --git a/drivers/rtc/rtc-armada38x.c b/drivers/rtc/rtc-armada38x.c
new file mode 100644
index 000000000000..06202dcf8001
--- /dev/null
+++ b/drivers/rtc/rtc-armada38x.c
@@ -0,0 +1,305 @@
+/*
+ * RTC driver for the Armada 38x Marvell SoCs
+ *
+ * Copyright (C) 2015 Marvell
+ *
+ * Gregory Clement <gregory.clement-wi1+55ScJUtKEb57/3fJTNBPR1lH4CV8@public.gmane.org>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of the
+ * License, or (at your option) any later version.
+ *
+ */
+
+#include <linux/delay.h>
+#include <linux/io.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/rtc.h>
+
+#define RTC_STATUS	    0x0
+#define RTC_STATUS_ALARM1	    BIT(0)
+#define RTC_STATUS_ALARM2	    BIT(1)
+#define RTC_IRQ1_CONF	    0x4
+#define RTC_IRQ1_AL_EN		    BIT(0)
+#define RTC_IRQ1_FREQ_EN	    BIT(1)
+#define RTC_IRQ1_FREQ_1HZ	    BIT(2)
+#define RTC_TIME	    0xC
+#define RTC_ALARM1	    0x10
+
+#define SOC_RTC_INTERRUPT   0x8
+#define SOC_RTC_ALARM1		BIT(0)
+#define SOC_RTC_ALARM2		BIT(1)
+#define SOC_RTC_ALARM1_MASK	BIT(2)
+#define SOC_RTC_ALARM2_MASK	BIT(3)
+
+struct armada38x_rtc {
+	struct rtc_device   *rtc_dev;
+	void __iomem	    *regs;
+	void __iomem	    *regs_soc;
+	spinlock_t	    lock;
+	int		    irq;
+};
+
+/*
+ * According to the datasheet, we need to wait for 5us between each
+ * write
+ */
+static void rtc_delayed_write(u32 val, struct armada38x_rtc *rtc, int offset)
+{
+	writel(val, rtc->regs + offset);
+	udelay(5);
+}
+
+static int armada38x_rtc_read_time(struct device *dev, struct rtc_time *tm)
+{
+	struct armada38x_rtc *rtc = dev_get_drvdata(dev);
+	unsigned long time, time_check, flags;
+
+	spin_lock_irqsave(&rtc->lock, flags);
+
+	time = readl(rtc->regs + RTC_TIME);
+	/*
+	 * WA for failing time set attempts. As stated in HW ERRATA if
+	 * more than one second between two time reads is detected
+	 * then read once again.
+	 */
+	time_check = readl(rtc->regs + RTC_TIME);
+	if ((time_check - time) > 1)
+		time_check = readl(rtc->regs + RTC_TIME);
+
+	spin_unlock_irqrestore(&rtc->lock, flags);
+
+	rtc_time_to_tm(time_check, tm);
+
+	return 0;
+}
+
+static int armada38x_rtc_set_time(struct device *dev, struct rtc_time *tm)
+{
+	struct armada38x_rtc *rtc = dev_get_drvdata(dev);
+	int ret = 0;
+	unsigned long time;
+
+	ret = rtc_tm_to_time(tm, &time);
+
+	if (ret)
+		goto out;
+	/*
+	 * Setting the RTC time not always succeeds. According to the
+	 * errata we need to first write on the status register and
+	 * then wait for 1s before writing to the time register to be
+	 * sure that the data will be taken into account.
+	 */
+	writel(0, rtc->regs + RTC_STATUS);
+	ssleep(1);
+
+	writel(time, rtc->regs + RTC_TIME);
+
+out:
+	return ret;
+}
+
+static int armada38x_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alrm)
+{
+	struct armada38x_rtc *rtc = dev_get_drvdata(dev);
+	unsigned long time, flags;
+	u32 val;
+
+	spin_lock_irqsave(&rtc->lock, flags);
+
+	time = readl(rtc->regs + RTC_ALARM1);
+	val = readl(rtc->regs + RTC_IRQ1_CONF) & RTC_IRQ1_AL_EN;
+
+	spin_unlock_irqrestore(&rtc->lock, flags);
+
+	alrm->enabled = val ? 1 : 0;
+	rtc_time_to_tm(time,  &alrm->time);
+
+	return 0;
+}
+
+static int armada38x_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alrm)
+{
+	struct armada38x_rtc *rtc = dev_get_drvdata(dev);
+	unsigned long time, flags;
+	int ret = 0;
+	u32 val;
+
+	ret = rtc_tm_to_time(&alrm->time, &time);
+
+	if (ret)
+		goto out;
+
+	spin_lock_irqsave(&rtc->lock, flags);
+
+	rtc_delayed_write(time, rtc, RTC_ALARM1);
+
+	if (alrm->enabled) {
+			rtc_delayed_write(RTC_IRQ1_AL_EN , rtc, RTC_IRQ1_CONF);
+			val = readl(rtc->regs_soc + SOC_RTC_INTERRUPT);
+		writel(val | SOC_RTC_ALARM1_MASK,
+			rtc->regs_soc + SOC_RTC_INTERRUPT);
+	}
+
+	spin_unlock_irqrestore(&rtc->lock, flags);
+
+out:
+	return ret;
+}
+
+static int armada38x_rtc_alarm_irq_enable(struct device *dev,
+					 unsigned int enabled)
+{
+	struct armada38x_rtc *rtc = dev_get_drvdata(dev);
+	unsigned long flags;
+
+	spin_lock_irqsave(&rtc->lock, flags);
+
+	if (enabled)
+		writel(RTC_IRQ1_AL_EN, rtc->regs + RTC_IRQ1_CONF);
+	else
+		writel(0, rtc->regs + RTC_IRQ1_CONF);
+
+	spin_unlock_irqrestore(&rtc->lock, flags);
+
+	return 0;
+}
+
+static irqreturn_t armada38x_rtc_alarm_irq(int irq, void *data)
+{
+	struct armada38x_rtc *rtc = data;
+	u32 val;
+	int event = RTC_IRQF | RTC_AF;
+
+	dev_dbg(&rtc->rtc_dev->dev, "%s:irq(%d)\n", __func__, irq);
+	val = readl(rtc->regs_soc + SOC_RTC_INTERRUPT);
+
+	spin_lock(&rtc->lock);
+
+	writel(val & ~SOC_RTC_ALARM1, rtc->regs_soc + SOC_RTC_INTERRUPT);
+	val = readl(rtc->regs + RTC_IRQ1_CONF);
+	/* disable all the interrupts for alarm 1 */
+	rtc_delayed_write(0, rtc, RTC_IRQ1_CONF);
+	/* Ack the event */
+	writel(RTC_STATUS_ALARM1, rtc->regs + RTC_STATUS);
+
+	spin_unlock(&rtc->lock);
+
+	if (val & RTC_IRQ1_FREQ_EN) {
+		if (val & RTC_IRQ1_FREQ_1HZ)
+			event |= RTC_UF;
+		else
+			event |= RTC_PF;
+	}
+
+	rtc_update_irq(rtc->rtc_dev, 1, event);
+
+	return IRQ_HANDLED;
+}
+
+static const struct rtc_class_ops armada38x_rtc_ops = {
+	.read_time = armada38x_rtc_read_time,
+	.set_time = armada38x_rtc_set_time,
+	.read_alarm = armada38x_rtc_read_alarm,
+	.set_alarm = armada38x_rtc_set_alarm,
+	.alarm_irq_enable = armada38x_rtc_alarm_irq_enable,
+};
+
+static __init int armada38x_rtc_probe(struct platform_device *pdev)
+{
+	struct resource *res;
+	struct armada38x_rtc *rtc;
+	int ret;
+
+	rtc = devm_kzalloc(&pdev->dev, sizeof(struct armada38x_rtc),
+			    GFP_KERNEL);
+	if (!rtc)
+		return -ENOMEM;
+
+	spin_lock_init(&rtc->lock);
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	rtc->regs = devm_ioremap_resource(&pdev->dev, res);
+	if (IS_ERR(rtc->regs))
+		return PTR_ERR(rtc->regs);
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 1);
+	rtc->regs_soc = devm_ioremap_resource(&pdev->dev, res);
+	if (IS_ERR(rtc->regs_soc))
+		return PTR_ERR(rtc->regs_soc);
+
+	rtc->irq = platform_get_irq(pdev, 0);
+
+	if (rtc->irq < 0) {
+		dev_err(&pdev->dev, "no irq\n");
+		return rtc->irq;
+	}
+	if (devm_request_irq(&pdev->dev, rtc->irq, armada38x_rtc_alarm_irq,
+				0, pdev->name, rtc) < 0) {
+		dev_warn(&pdev->dev, "Interrupt not available.\n");
+		rtc->irq = -1;
+	}
+	platform_set_drvdata(pdev, rtc);
+
+	device_init_wakeup(&pdev->dev, 1);
+	rtc->rtc_dev = devm_rtc_device_register(&pdev->dev, pdev->name,
+					&armada38x_rtc_ops, THIS_MODULE);
+	if (IS_ERR(rtc->rtc_dev)) {
+		ret = PTR_ERR(rtc->rtc_dev);
+		dev_err(&pdev->dev, "Failed to register RTC device: %d\n", ret);
+		if (ret == 0)
+			ret = -EINVAL;
+		return ret;
+	}
+	return 0;
+}
+
+#ifdef CONFIG_PM_SLEEP
+static int armada38x_rtc_suspend(struct device *dev)
+{
+	if (device_may_wakeup(dev)) {
+		struct armada38x_rtc *rtc = dev_get_drvdata(dev);
+
+		return enable_irq_wake(rtc->irq);
+	}
+
+	return 0;
+}
+
+static int armada38x_rtc_resume(struct device *dev)
+{
+	if (device_may_wakeup(dev)) {
+		struct armada38x_rtc *rtc = dev_get_drvdata(dev);
+
+		return disable_irq_wake(rtc->irq);
+	}
+
+	return 0;
+}
+#endif
+
+static SIMPLE_DEV_PM_OPS(armada38x_rtc_pm_ops,
+			 armada38x_rtc_suspend, armada38x_rtc_resume);
+
+#ifdef CONFIG_OF
+static const struct of_device_id armada38x_rtc_of_match_table[] = {
+	{ .compatible = "marvell,armada-380-rtc", },
+	{}
+};
+#endif
+
+static struct platform_driver armada38x_rtc_driver = {
+	.driver		= {
+		.name	= "armada38x-rtc",
+		.pm	= &armada38x_rtc_pm_ops,
+		.of_match_table = of_match_ptr(armada38x_rtc_of_match_table),
+	},
+};
+
+module_platform_driver_probe(armada38x_rtc_driver, armada38x_rtc_probe);
+
+MODULE_DESCRIPTION("Marvell Armada 38x RTC driver");
+MODULE_AUTHOR("Gregory CLEMENT <gregory.clement-wi1+55ScJUtKEb57/3fJTNBPR1lH4CV8@public.gmane.org>");
+MODULE_LICENSE("GPL");
-- 
1.9.1

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[PATCH 3/4] MAINTAINERS: Add the RTC driver for the Armada38x

[Gregory CLEMENT]

Put it in the mvebu entry.

Signed-off-by: Gregory CLEMENT <gregory.clement@free-electrons.com>
---
 MAINTAINERS | 1 +
 1 file changed, 1 insertion(+)

diff --git a/MAINTAINERS b/MAINTAINERS
index ddb9ac8d32b3..49ce80ef3894 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -1157,6 +1157,7 @@ M:	Sebastian Hesselbarth <sebastian.hesselbarth@gmail.com>
 L:	linux-arm-kernel@lists.infradead.org (moderated for non-subscribers)
 S:	Maintained
 F:	arch/arm/mach-mvebu/
+F:  drivers/rtc/armada38x-rtc
 
 ARM/Marvell Berlin SoC support
 M:	Sebastian Hesselbarth <sebastian.hesselbarth@gmail.com>
-- 
1.9.1

[PATCH 4/4] ARM: mvebu: add Device Tree description of RTC on Armada 38x

[Gregory CLEMENT]

The Marvell Armada 38x SoCs contains an RTC which differs from the RTC
used in the other mvebu SoCs until now. This commit adds the Device
Tree description of this interface at the SoC level.

Signed-off-by: Gregory CLEMENT <gregory.clement-wi1+55ScJUtKEb57/3fJTNBPR1lH4CV8@public.gmane.org>
---
 arch/arm/boot/dts/armada-38x.dtsi | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/arch/arm/boot/dts/armada-38x.dtsi b/arch/arm/boot/dts/armada-38x.dtsi
index 04fe80d101f8..22909add8889 100644
--- a/arch/arm/boot/dts/armada-38x.dtsi
+++ b/arch/arm/boot/dts/armada-38x.dtsi
@@ -466,6 +466,12 @@
 				clocks = <&gateclk 4>;
 			};
 
+			rtc@184a8 {
+				compatible = "marvell,armada-380-rtc";
+				reg = <0xa3800 0x20>, <0x184a0 0x0c>;
+				interrupts = <GIC_SPI 21 IRQ_TYPE_LEVEL_HIGH>;
+			};
+
 			sata@a8000 {
 				compatible = "marvell,armada-380-ahci";
 				reg = <0xa8000 0x2000>;
-- 
1.9.1

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Re: [PATCH 3/4] MAINTAINERS: Add the RTC driver for the Armada38x

[Sergei Shtylyov]

Hello.

On 1/9/2015 6:32 PM, Gregory CLEMENT wrote:

> Put it in the mvebu entry.

> Signed-off-by: Gregory CLEMENT <gregory.clement-wi1+55ScJUtKEb57/3fJTNBPR1lH4CV8@public.gmane.org>
> ---
>   MAINTAINERS | 1 +
>   1 file changed, 1 insertion(+)

> diff --git a/MAINTAINERS b/MAINTAINERS
> index ddb9ac8d32b3..49ce80ef3894 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -1157,6 +1157,7 @@ M:	Sebastian Hesselbarth <sebastian.hesselbarth-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
>   L:	linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org (moderated for non-subscribers)
>   S:	Maintained
>   F:	arch/arm/mach-mvebu/
> +F:  drivers/rtc/armada38x-rtc

    Please use tab, not spaces after "F:".

WBR, Sergei

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Re: [PATCH 1/4] rtc: armada38x: Add the device tree binding documentation

[Arnaud Ebalard]

Hi Gregory,

Gregory CLEMENT <gregory.clement-wi1+55ScJUtKEb57/3fJTNBPR1lH4CV8@public.gmane.org> writes:

> The Armada 38x SoCs come with a new RTC which differs from the one
> used in the other mvebu SoCs until now. This patch describes the
> binding of this RTC.
>
> Signed-off-by: Gregory CLEMENT <gregory.clement-wi1+55ScJUtKEb57/3fJTNBPR1lH4CV8@public.gmane.org>
> ---
>  .../devicetree/bindings/rtc/armada-380-rtc.txt          | 17 +++++++++++++++++
>  1 file changed, 17 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/rtc/armada-380-rtc.txt
>
> diff --git a/Documentation/devicetree/bindings/rtc/armada-380-rtc.txt b/Documentation/devicetree/bindings/rtc/armada-380-rtc.txt
> new file mode 100644
> index 000000000000..2c56bef9dd7e
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/rtc/armada-380-rtc.txt
> @@ -0,0 +1,17 @@
> +* Real Time Clock of te Armada 38x SoCs
> +
> +RTC controller for the Armada 38x SoCs
> +
> +Required properties:
> +- compatible : Should be "marvell,armada-380-rtc"
> +- reg: physical base address of the controller and length of memory mapped
> +  region. The second entires is for the IP configuration part.
                        ^^^^^^^
                        entry

I had to read probe function to understand precisely the purpose of each
region, i.e. IMHO the description could be made a bit clearer.

> +- interrupts: IRQ line for the RTC.
>
> +
> +Example:
> +
> +rtc@184a8 {
> +	compatible = "marvell,armada-380-rtc";
> +	reg = <0xa3800 0x20>, <0x184a0 0x0c>;
> +	interrupts = <GIC_SPI 21 IRQ_TYPE_LEVEL_HIGH>;
> +};
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Re: [PATCH 2/4] drivers/rtc/rtc-armada38x: Add a new RTC driver for recent mvebu SoCs

[Arnaud Ebalard]

Hi Gregory,

Gregory CLEMENT <gregory.clement-wi1+55ScJUtKEb57/3fJTNBPR1lH4CV8@public.gmane.org> writes:

> The new mvebu SoCs come with a new RTC driver. This patch adds the
> support for this new IP which is currently found in the Armada 38x
> SoCs.
>
> This RTC provides two alarms, but only the first one is used in the
> driver. The RTC also allows using periodic interrupts.
>
> Signed-off-by: Gregory CLEMENT <gregory.clement-wi1+55ScJUtKEb57/3fJTNBPR1lH4CV8@public.gmane.org>
> ---
>  drivers/rtc/Kconfig         |  10 ++
>  drivers/rtc/Makefile        |   1 +
>  drivers/rtc/rtc-armada38x.c | 305 ++++++++++++++++++++++++++++++++++++++++++++
>  3 files changed, 316 insertions(+)
>  create mode 100644 drivers/rtc/rtc-armada38x.c
>
> diff --git a/drivers/rtc/Kconfig b/drivers/rtc/Kconfig
> index f15cddfeb897..de42ebd4b626 100644
> --- a/drivers/rtc/Kconfig
> +++ b/drivers/rtc/Kconfig
> @@ -1269,6 +1269,16 @@ config RTC_DRV_MV
>  	  This driver can also be built as a module. If so, the module
>  	  will be called rtc-mv.
>  
> +config RTC_DRV_ARMADA38X
> +	tristate "Armada 38x Marvell SoC RTC"
> +	depends on ARCH_MVEBU
> +	help
> +	  If you say yes here you will get support for the in-chip RTC
> +	  that can be found in the Armada 38x Marvell's SoC device
> +
> +	  This driver can also be built as a module. If so, the module
> +	  will be called armada38x-rtc.
> +
>  config RTC_DRV_PS3
>  	tristate "PS3 RTC"
>  	depends on PPC_PS3
> diff --git a/drivers/rtc/Makefile b/drivers/rtc/Makefile
> index c8ef3e1e6ccd..03fe5629c464 100644
> --- a/drivers/rtc/Makefile
> +++ b/drivers/rtc/Makefile
> @@ -24,6 +24,7 @@ obj-$(CONFIG_RTC_DRV_88PM860X)  += rtc-88pm860x.o
>  obj-$(CONFIG_RTC_DRV_88PM80X)	+= rtc-88pm80x.o
>  obj-$(CONFIG_RTC_DRV_AB3100)	+= rtc-ab3100.o
>  obj-$(CONFIG_RTC_DRV_AB8500)	+= rtc-ab8500.o
> +obj-$(CONFIG_RTC_DRV_ARMADA38X)	+= rtc-armada38x.o
>  obj-$(CONFIG_RTC_DRV_AS3722)	+= rtc-as3722.o
>  obj-$(CONFIG_RTC_DRV_AT32AP700X)+= rtc-at32ap700x.o
>  obj-$(CONFIG_RTC_DRV_AT91RM9200)+= rtc-at91rm9200.o
> diff --git a/drivers/rtc/rtc-armada38x.c b/drivers/rtc/rtc-armada38x.c
> new file mode 100644
> index 000000000000..06202dcf8001
> --- /dev/null
> +++ b/drivers/rtc/rtc-armada38x.c
> @@ -0,0 +1,305 @@
> +/*
> + * RTC driver for the Armada 38x Marvell SoCs
> + *
> + * Copyright (C) 2015 Marvell
> + *
> + * Gregory Clement <gregory.clement-wi1+55ScJUtKEb57/3fJTNBPR1lH4CV8@public.gmane.org>
> + *
> + * This program is free software; you can redistribute it and/or
> + * modify it under the terms of the GNU General Public License as
> + * published by the Free Software Foundation; either version 2 of the
> + * License, or (at your option) any later version.
> + *
> + */
> +
> +#include <linux/delay.h>
> +#include <linux/io.h>
> +#include <linux/module.h>
> +#include <linux/of.h>
> +#include <linux/platform_device.h>
> +#include <linux/rtc.h>
> +
> +#define RTC_STATUS	    0x0
> +#define RTC_STATUS_ALARM1	    BIT(0)
> +#define RTC_STATUS_ALARM2	    BIT(1)
> +#define RTC_IRQ1_CONF	    0x4
> +#define RTC_IRQ1_AL_EN		    BIT(0)
> +#define RTC_IRQ1_FREQ_EN	    BIT(1)
> +#define RTC_IRQ1_FREQ_1HZ	    BIT(2)
> +#define RTC_TIME	    0xC
> +#define RTC_ALARM1	    0x10
> +
> +#define SOC_RTC_INTERRUPT   0x8
> +#define SOC_RTC_ALARM1		BIT(0)
> +#define SOC_RTC_ALARM2		BIT(1)
> +#define SOC_RTC_ALARM1_MASK	BIT(2)
> +#define SOC_RTC_ALARM2_MASK	BIT(3)
> +
> +struct armada38x_rtc {
> +	struct rtc_device   *rtc_dev;
> +	void __iomem	    *regs;
> +	void __iomem	    *regs_soc;
> +	spinlock_t	    lock;

out of curiosity, why use a spinlock and not a mutex?


> +	int		    irq;
> +};
> +
> +/*
> + * According to the datasheet, we need to wait for 5us between each
> + * write
> + */
> +static void rtc_delayed_write(u32 val, struct armada38x_rtc *rtc, int offset)
> +{
> +	writel(val, rtc->regs + offset);
> +	udelay(5);
> +}

In the remaining of the driver, you have various direct calls to writel()
w/o that 5µs protection, to update/modifiy rtc registers. Is that 5µs
trick specific to a given subpart of the registers? In that case, I
guess it would help to update the comment.


> +
> +static int armada38x_rtc_read_time(struct device *dev, struct rtc_time *tm)
> +{
> +	struct armada38x_rtc *rtc = dev_get_drvdata(dev);
> +	unsigned long time, time_check, flags;
> +
> +	spin_lock_irqsave(&rtc->lock, flags);
> +
> +	time = readl(rtc->regs + RTC_TIME);
> +	/*
> +	 * WA for failing time set attempts. As stated in HW ERRATA if
> +	 * more than one second between two time reads is detected
> +	 * then read once again.
> +	 */
> +	time_check = readl(rtc->regs + RTC_TIME);
> +	if ((time_check - time) > 1)
> +		time_check = readl(rtc->regs + RTC_TIME);

Bear with me; I don't have access to HW ERRATA.

Are you guaranteed to get a valid value at third read if you got a bad
one before, i.e. no need to put a while loop around that workaround? 

Additionally, the workaround seems to be related to time
setting. Looking at time setting code below, it seems the issue is also
created by the fact the writel() call is not under the protection of the
spinlock.

> +
> +	spin_unlock_irqrestore(&rtc->lock, flags);
> +
> +	rtc_time_to_tm(time_check, tm);
> +
> +	return 0;

Does the block provide anyway to detect the oscillator was not running,
i.e. the value we are reading is not valid?


> +}
> +
> +static int armada38x_rtc_set_time(struct device *dev, struct rtc_time *tm)
> +{
> +	struct armada38x_rtc *rtc = dev_get_drvdata(dev);
> +	int ret = 0;
> +	unsigned long time;
> +
> +	ret = rtc_tm_to_time(tm, &time);


> +
> +	if (ret)
> +		goto out;
> +	/*
> +	 * Setting the RTC time not always succeeds. According to the
> +	 * errata we need to first write on the status register and
> +	 * then wait for 1s before writing to the time register to be
> +	 * sure that the data will be taken into account.
> +	 */
> +	writel(0, rtc->regs + RTC_STATUS);
> +	ssleep(1);
> +
> +	writel(time, rtc->regs + RTC_TIME);

I think writel(time + 1, ...) would correct the one second shift you
introduce using you ssleep() above.

Additionally, as discussed above, I do not see why you're not protecting
the write using you spinlock.


> +
> +out:
> +	return ret;
> +}
> +
> +static int armada38x_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alrm)
> +{
> +	struct armada38x_rtc *rtc = dev_get_drvdata(dev);
> +	unsigned long time, flags;
> +	u32 val;
> +
> +	spin_lock_irqsave(&rtc->lock, flags);
> +
> +	time = readl(rtc->regs + RTC_ALARM1);
> +	val = readl(rtc->regs + RTC_IRQ1_CONF) & RTC_IRQ1_AL_EN;
> +
> +	spin_unlock_irqrestore(&rtc->lock, flags);
> +
> +	alrm->enabled = val ? 1 : 0;
> +	rtc_time_to_tm(time,  &alrm->time);
> +
> +	return 0;
> +}
> +

In the two functions below, regarding RTC interrupt activation, do you
need a check that a valid IRQ was passed in the .dts and that
devm_request_irq() went ok in probe(), i.e. that rtc->irq > 0?

> +static int armada38x_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alrm)
> +{
> +	struct armada38x_rtc *rtc = dev_get_drvdata(dev);
> +	unsigned long time, flags;
> +	int ret = 0;
> +	u32 val;
> +
> +	ret = rtc_tm_to_time(&alrm->time, &time);
> +
> +	if (ret)
> +		goto out;
> +
> +	spin_lock_irqsave(&rtc->lock, flags);
> +
> +	rtc_delayed_write(time, rtc, RTC_ALARM1);
> +
> +	if (alrm->enabled) {
> +			rtc_delayed_write(RTC_IRQ1_AL_EN , rtc, RTC_IRQ1_CONF);
> +			val = readl(rtc->regs_soc + SOC_RTC_INTERRUPT);
> +		writel(val | SOC_RTC_ALARM1_MASK,
> +			rtc->regs_soc + SOC_RTC_INTERRUPT);
> +	}
> +
> +	spin_unlock_irqrestore(&rtc->lock, flags);
> +
> +out:
> +	return ret;
> +}
> +
> +static int armada38x_rtc_alarm_irq_enable(struct device *dev,
> +					 unsigned int enabled)
> +{
> +	struct armada38x_rtc *rtc = dev_get_drvdata(dev);
> +	unsigned long flags;
> +
> +	spin_lock_irqsave(&rtc->lock, flags);
> +
> +	if (enabled)
> +		writel(RTC_IRQ1_AL_EN, rtc->regs + RTC_IRQ1_CONF);
> +	else
> +		writel(0, rtc->regs + RTC_IRQ1_CONF);

I find the following more readable, but it is subjective:

writel(enabled ? RTC_IRQ1_AL_EN : 0, rtc->regs + RTC_IRQ1_CONF);


> +
> +	spin_unlock_irqrestore(&rtc->lock, flags);
> +
> +	return 0;
> +}
> +
> +static irqreturn_t armada38x_rtc_alarm_irq(int irq, void *data)
> +{
> +	struct armada38x_rtc *rtc = data;
> +	u32 val;
> +	int event = RTC_IRQF | RTC_AF;
> +
> +	dev_dbg(&rtc->rtc_dev->dev, "%s:irq(%d)\n", __func__, irq);
> +	val = readl(rtc->regs_soc + SOC_RTC_INTERRUPT);
> +
> +	spin_lock(&rtc->lock);
> +
> +	writel(val & ~SOC_RTC_ALARM1, rtc->regs_soc + SOC_RTC_INTERRUPT);

Why not putting the readl() above under protection of the spinlock to
protect a change that could occur between the readl() and the writel()?


> +	val = readl(rtc->regs + RTC_IRQ1_CONF);
> +	/* disable all the interrupts for alarm 1 */
> +	rtc_delayed_write(0, rtc, RTC_IRQ1_CONF);
> +	/* Ack the event */
> +	writel(RTC_STATUS_ALARM1, rtc->regs + RTC_STATUS);
> +
> +	spin_unlock(&rtc->lock);
> +
> +	if (val & RTC_IRQ1_FREQ_EN) {
> +		if (val & RTC_IRQ1_FREQ_1HZ)
> +			event |= RTC_UF;
> +		else
> +			event |= RTC_PF;
> +	}
> +
> +	rtc_update_irq(rtc->rtc_dev, 1, event);
> +
> +	return IRQ_HANDLED;
> +}
> +
> +static const struct rtc_class_ops armada38x_rtc_ops = {
> +	.read_time = armada38x_rtc_read_time,
> +	.set_time = armada38x_rtc_set_time,
> +	.read_alarm = armada38x_rtc_read_alarm,
> +	.set_alarm = armada38x_rtc_set_alarm,
> +	.alarm_irq_enable = armada38x_rtc_alarm_irq_enable,
> +};
> +
> +static __init int armada38x_rtc_probe(struct platform_device *pdev)
> +{
> +	struct resource *res;
> +	struct armada38x_rtc *rtc;
> +	int ret;
> +
> +	rtc = devm_kzalloc(&pdev->dev, sizeof(struct armada38x_rtc),
> +			    GFP_KERNEL);
> +	if (!rtc)
> +		return -ENOMEM;
> +
> +	spin_lock_init(&rtc->lock);
> +
> +	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> +	rtc->regs = devm_ioremap_resource(&pdev->dev, res);
> +	if (IS_ERR(rtc->regs))
> +		return PTR_ERR(rtc->regs);
> +	res = platform_get_resource(pdev, IORESOURCE_MEM, 1);
> +	rtc->regs_soc = devm_ioremap_resource(&pdev->dev, res);
> +	if (IS_ERR(rtc->regs_soc))
> +		return PTR_ERR(rtc->regs_soc);
> +
> +	rtc->irq = platform_get_irq(pdev, 0);
> +
> +	if (rtc->irq < 0) {
> +		dev_err(&pdev->dev, "no irq\n");
> +		return rtc->irq;
> +	}
> +	if (devm_request_irq(&pdev->dev, rtc->irq, armada38x_rtc_alarm_irq,
> +				0, pdev->name, rtc) < 0) {
> +		dev_warn(&pdev->dev, "Interrupt not available.\n");
> +		rtc->irq = -1;
> +	}
> +	platform_set_drvdata(pdev, rtc);
> +
> +	device_init_wakeup(&pdev->dev, 1);

if devm_request_irq() returns an error, should device_init_wakeup() be
called? See comment below under armada38x_rtc_suspend().

> +	rtc->rtc_dev = devm_rtc_device_register(&pdev->dev, pdev->name,
> +					&armada38x_rtc_ops, THIS_MODULE);
> +	if (IS_ERR(rtc->rtc_dev)) {
> +		ret = PTR_ERR(rtc->rtc_dev);
> +		dev_err(&pdev->dev, "Failed to register RTC device: %d\n", ret);
> +		if (ret == 0)
> +			ret = -EINVAL;

I may be missing something but I do not see how ret can be 0 above
because the initial check uses IS_ERR() and not IS_ERR_OR_NULL().


> +		return ret;
> +	}
> +	return 0;
> +}
> +
> +#ifdef CONFIG_PM_SLEEP
> +static int armada38x_rtc_suspend(struct device *dev)
> +{
> +	if (device_may_wakeup(dev)) {
> +		struct armada38x_rtc *rtc = dev_get_drvdata(dev);
> +
> +		return enable_irq_wake(rtc->irq);
> +	}

AFAICT, rtc->irq maybe -1 in the call above. You need to either call
device_init_wakeup() when devm_request_irq() succeed or check rtc->irq
is valid in the "if" above.

> +
> +	return 0;
> +}
> +
> +static int armada38x_rtc_resume(struct device *dev)
> +{
> +	if (device_may_wakeup(dev)) {
> +		struct armada38x_rtc *rtc = dev_get_drvdata(dev);
> +
> +		return disable_irq_wake(rtc->irq);
> +	}
> +
> +	return 0;
> +}
> +#endif
> +
> +static SIMPLE_DEV_PM_OPS(armada38x_rtc_pm_ops,
> +			 armada38x_rtc_suspend, armada38x_rtc_resume);
> +
> +#ifdef CONFIG_OF
> +static const struct of_device_id armada38x_rtc_of_match_table[] = {
> +	{ .compatible = "marvell,armada-380-rtc", },
> +	{}
> +};
> +#endif
> +
> +static struct platform_driver armada38x_rtc_driver = {
> +	.driver		= {
> +		.name	= "armada38x-rtc",
> +		.pm	= &armada38x_rtc_pm_ops,
> +		.of_match_table = of_match_ptr(armada38x_rtc_of_match_table),
> +	},
> +};
> +
> +module_platform_driver_probe(armada38x_rtc_driver, armada38x_rtc_probe);
> +
> +MODULE_DESCRIPTION("Marvell Armada 38x RTC driver");
> +MODULE_AUTHOR("Gregory CLEMENT <gregory.clement-wi1+55ScJUtKEb57/3fJTNBPR1lH4CV8@public.gmane.org>");
> +MODULE_LICENSE("GPL");
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Re: [PATCH 4/4] ARM: mvebu: add Device Tree description of RTC on Armada 38x

[Arnaud Ebalard]

Hi Gregory,

Gregory CLEMENT <gregory.clement-wi1+55ScJUtKEb57/3fJTNBPR1lH4CV8@public.gmane.org> writes:

> The Marvell Armada 38x SoCs contains an RTC which differs from the RTC
> used in the other mvebu SoCs until now. This commit adds the Device
> Tree description of this interface at the SoC level.
>
> Signed-off-by: Gregory CLEMENT <gregory.clement-wi1+55ScJUtKEb57/3fJTNBPR1lH4CV8@public.gmane.org>
> ---
>  arch/arm/boot/dts/armada-38x.dtsi | 6 ++++++
>  1 file changed, 6 insertions(+)
>
> diff --git a/arch/arm/boot/dts/armada-38x.dtsi b/arch/arm/boot/dts/armada-38x.dtsi
> index 04fe80d101f8..22909add8889 100644
> --- a/arch/arm/boot/dts/armada-38x.dtsi
> +++ b/arch/arm/boot/dts/armada-38x.dtsi
> @@ -466,6 +466,12 @@
>  				clocks = <&gateclk 4>;
>  			};
>  
> +			rtc@184a8 {
> +				compatible = "marvell,armada-380-rtc";
> +				reg = <0xa3800 0x20>, <0x184a0 0x0c>;
> +				interrupts = <GIC_SPI 21 IRQ_TYPE_LEVEL_HIGH>;
> +			};
> +

Out of curiosity, why not naming the node rtc@a3800? Main argument:
least expectation principle when reading the .dtsi and expecting
increasing addresses. Or did I miss sth else?


>  			sata@a8000 {
>  				compatible = "marvell,armada-380-ahci";
>  				reg = <0xa8000 0x2000>;
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Re: [PATCH 1/4] rtc: armada38x: Add the device tree binding documentation

[Maxime Ripard]

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On Wed, Jan 14, 2015 at 12:02:27AM +0100, Arnaud Ebalard wrote:
> Hi Gregory,
> 
> Gregory CLEMENT <gregory.clement-wi1+55ScJUtKEb57/3fJTNBPR1lH4CV8@public.gmane.org> writes:
> 
> > The Armada 38x SoCs come with a new RTC which differs from the one
> > used in the other mvebu SoCs until now. This patch describes the
> > binding of this RTC.
> >
> > Signed-off-by: Gregory CLEMENT <gregory.clement-wi1+55ScJUtKEb57/3fJTNBPR1lH4CV8@public.gmane.org>
> > ---
> >  .../devicetree/bindings/rtc/armada-380-rtc.txt          | 17 +++++++++++++++++
> >  1 file changed, 17 insertions(+)
> >  create mode 100644 Documentation/devicetree/bindings/rtc/armada-380-rtc.txt
> >
> > diff --git a/Documentation/devicetree/bindings/rtc/armada-380-rtc.txt b/Documentation/devicetree/bindings/rtc/armada-380-rtc.txt
> > new file mode 100644
> > index 000000000000..2c56bef9dd7e
> > --- /dev/null
> > +++ b/Documentation/devicetree/bindings/rtc/armada-380-rtc.txt
> > @@ -0,0 +1,17 @@
> > +* Real Time Clock of te Armada 38x SoCs
> > +
> > +RTC controller for the Armada 38x SoCs
> > +
> > +Required properties:
> > +- compatible : Should be "marvell,armada-380-rtc"
> > +- reg: physical base address of the controller and length of memory mapped
> > +  region. The second entires is for the IP configuration part.
>                         ^^^^^^^
>                         entry
> 
> I had to read probe function to understand precisely the purpose of each
> region, i.e. IMHO the description could be made a bit clearer.

Maybe using reg-names would make it easier to understand, both in the
documentation and the DT itself (as well as not needing to enforce a
particular ordering of the two areas in the documentation)

Maxime

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

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Re: [PATCH 4/4] ARM: mvebu: add Device Tree description of RTC on Armada 38x

[Maxime Ripard]

[-- Attachment #1: Type: text/plain, Size: 1537 bytes --]

On Wed, Jan 14, 2015 at 12:03:12AM +0100, Arnaud Ebalard wrote:
> Hi Gregory,
> 
> Gregory CLEMENT <gregory.clement-wi1+55ScJUtKEb57/3fJTNBPR1lH4CV8@public.gmane.org> writes:
> 
> > The Marvell Armada 38x SoCs contains an RTC which differs from the RTC
> > used in the other mvebu SoCs until now. This commit adds the Device
> > Tree description of this interface at the SoC level.
> >
> > Signed-off-by: Gregory CLEMENT <gregory.clement-wi1+55ScJUtKEb57/3fJTNBPR1lH4CV8@public.gmane.org>
> > ---
> >  arch/arm/boot/dts/armada-38x.dtsi | 6 ++++++
> >  1 file changed, 6 insertions(+)
> >
> > diff --git a/arch/arm/boot/dts/armada-38x.dtsi b/arch/arm/boot/dts/armada-38x.dtsi
> > index 04fe80d101f8..22909add8889 100644
> > --- a/arch/arm/boot/dts/armada-38x.dtsi
> > +++ b/arch/arm/boot/dts/armada-38x.dtsi
> > @@ -466,6 +466,12 @@
> >  				clocks = <&gateclk 4>;
> >  			};
> >  
> > +			rtc@184a8 {
> > +				compatible = "marvell,armada-380-rtc";
> > +				reg = <0xa3800 0x20>, <0x184a0 0x0c>;
> > +				interrupts = <GIC_SPI 21 IRQ_TYPE_LEVEL_HIGH>;
> > +			};
> > +
> 
> Out of curiosity, why not naming the node rtc@a3800? Main argument:
> least expectation principle when reading the .dtsi and expecting
> increasing addresses. Or did I miss sth else?

Actually, the ePAPR even states that the unit-adress must be the first
address in reg (section 2.2.1.1 of the ePAPR 1.1)

Maxime

-- 
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Embedded Linux, Kernel and Android engineering
http://free-electrons.com

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Re: [PATCH 1/4] rtc: armada38x: Add the device tree binding documentation

[Gregory CLEMENT]

Hi Arnaud,

First, thanks for your extensive review.

On 14/01/2015 00:02, Arnaud Ebalard wrote:
> Hi Gregory,
> 
> Gregory CLEMENT <gregory.clement-wi1+55ScJUtKEb57/3fJTNBPR1lH4CV8@public.gmane.org> writes:
> 
>> The Armada 38x SoCs come with a new RTC which differs from the one
>> used in the other mvebu SoCs until now. This patch describes the
>> binding of this RTC.
>>
>> Signed-off-by: Gregory CLEMENT <gregory.clement-wi1+55ScJUtKEb57/3fJTNBPR1lH4CV8@public.gmane.org>
>> ---
>>  .../devicetree/bindings/rtc/armada-380-rtc.txt          | 17 +++++++++++++++++
>>  1 file changed, 17 insertions(+)
>>  create mode 100644 Documentation/devicetree/bindings/rtc/armada-380-rtc.txt
>>
>> diff --git a/Documentation/devicetree/bindings/rtc/armada-380-rtc.txt b/Documentation/devicetree/bindings/rtc/armada-380-rtc.txt
>> new file mode 100644
>> index 000000000000..2c56bef9dd7e
>> --- /dev/null
>> +++ b/Documentation/devicetree/bindings/rtc/armada-380-rtc.txt
>> @@ -0,0 +1,17 @@
>> +* Real Time Clock of te Armada 38x SoCs
>> +
>> +RTC controller for the Armada 38x SoCs
>> +
>> +Required properties:
>> +- compatible : Should be "marvell,armada-380-rtc"
>> +- reg: physical base address of the controller and length of memory mapped
>> +  region. The second entires is for the IP configuration part.
>                         ^^^^^^^
>                         entry
> 
> I had to read probe function to understand precisely the purpose of each
> region, i.e. IMHO the description could be made a bit clearer.

Right, and as suggested by Maxime I will use reg-names

> 
>> +- interrupts: IRQ line for the RTC.
>>
>> +
>> +Example:
>> +
>> +rtc@184a8 {
>> +	compatible = "marvell,armada-380-rtc";
>> +	reg = <0xa3800 0x20>, <0x184a0 0x0c>;
>> +	interrupts = <GIC_SPI 21 IRQ_TYPE_LEVEL_HIGH>;
>> +};


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Re: [PATCH 4/4] ARM: mvebu: add Device Tree description of RTC on Armada 38x

[Gregory CLEMENT]

Hi Arnaud,

On 14/01/2015 00:03, Arnaud Ebalard wrote:
> Hi Gregory,
> 
> Gregory CLEMENT <gregory.clement-wi1+55ScJUtKEb57/3fJTNBPR1lH4CV8@public.gmane.org> writes:
> 
>> The Marvell Armada 38x SoCs contains an RTC which differs from the RTC
>> used in the other mvebu SoCs until now. This commit adds the Device
>> Tree description of this interface at the SoC level.
>>
>> Signed-off-by: Gregory CLEMENT <gregory.clement-wi1+55ScJUtKEb57/3fJTNBPR1lH4CV8@public.gmane.org>
>> ---
>>  arch/arm/boot/dts/armada-38x.dtsi | 6 ++++++
>>  1 file changed, 6 insertions(+)
>>
>> diff --git a/arch/arm/boot/dts/armada-38x.dtsi b/arch/arm/boot/dts/armada-38x.dtsi
>> index 04fe80d101f8..22909add8889 100644
>> --- a/arch/arm/boot/dts/armada-38x.dtsi
>> +++ b/arch/arm/boot/dts/armada-38x.dtsi
>> @@ -466,6 +466,12 @@
>>  				clocks = <&gateclk 4>;
>>  			};
>>  
>> +			rtc@184a8 {
>> +				compatible = "marvell,armada-380-rtc";
>> +				reg = <0xa3800 0x20>, <0x184a0 0x0c>;
>> +				interrupts = <GIC_SPI 21 IRQ_TYPE_LEVEL_HIGH>;
>> +			};
>> +
> 
> Out of curiosity, why not naming the node rtc@a3800? Main argument:
> least expectation principle when reading the .dtsi and expecting
> increasing addresses. Or did I miss sth else?

It was a mistake, I should have used the 0xa3800 offset to name it because
most of the RTC registers are located here.


Thanks,

Gregory

> 
> 
>>  			sata@a8000 {
>>  				compatible = "marvell,armada-380-ahci";
>>  				reg = <0xa8000 0x2000>;


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Re: [PATCH 2/4] drivers/rtc/rtc-armada38x: Add a new RTC driver for recent mvebu SoCs

[Gregory CLEMENT]

Hi Arnaud,

[...]
>> +struct armada38x_rtc {
>> +	struct rtc_device   *rtc_dev;
>> +	void __iomem	    *regs;
>> +	void __iomem	    *regs_soc;
>> +	spinlock_t	    lock;
> 
> out of curiosity, why use a spinlock and not a mutex?

To be able to use it in the interrupt context.

> 
> 
>> +	int		    irq;
>> +};
>> +
>> +/*
>> + * According to the datasheet, we need to wait for 5us between each
>> + * write
>> + */
>> +static void rtc_delayed_write(u32 val, struct armada38x_rtc *rtc, int offset)
>> +{
>> +	writel(val, rtc->regs + offset);
>> +	udelay(5);
>> +}
> 
> In the remaining of the driver, you have various direct calls to writel()
> w/o that 5µs protection, to update/modifiy rtc registers. Is that 5µs
> trick specific to a given subpart of the registers? In that case, I
> guess it would help to update the comment.

This direct call were done because there was not a call to write just after.
As explained in the comment the 5us is needed only _between_ two consecutive
write. I can emphasize it needed.

> 
> 
>> +
>> +static int armada38x_rtc_read_time(struct device *dev, struct rtc_time *tm)
>> +{
>> +	struct armada38x_rtc *rtc = dev_get_drvdata(dev);
>> +	unsigned long time, time_check, flags;
>> +
>> +	spin_lock_irqsave(&rtc->lock, flags);
>> +
>> +	time = readl(rtc->regs + RTC_TIME);
>> +	/*
>> +	 * WA for failing time set attempts. As stated in HW ERRATA if
>> +	 * more than one second between two time reads is detected
>> +	 * then read once again.
>> +	 */
>> +	time_check = readl(rtc->regs + RTC_TIME);
>> +	if ((time_check - time) > 1)
>> +		time_check = readl(rtc->regs + RTC_TIME);
> 
> Bear with me; I don't have access to HW ERRATA.
> 
> Are you guaranteed to get a valid value at third read if you got a bad
> one before, i.e. no need to put a while loop around that workaround?

I don't have enough information to answer you, maybe the Marvell designer can
answer it. I will ask.

> 
> Additionally, the workaround seems to be related to time
> setting. Looking at time setting code below, it seems the issue is also
> created by the fact the writel() call is not under the protection of the
> spinlock.
> 
>> +
>> +	spin_unlock_irqrestore(&rtc->lock, flags);
>> +
>> +	rtc_time_to_tm(time_check, tm);
>> +
>> +	return 0;
> 
> Does the block provide anyway to detect the oscillator was not running,
> i.e. the value we are reading is not valid?

I didn't see anything related to this, but here again I will ask.

> 
> 
>> +}
>> +
>> +static int armada38x_rtc_set_time(struct device *dev, struct rtc_time *tm)
>> +{
>> +	struct armada38x_rtc *rtc = dev_get_drvdata(dev);
>> +	int ret = 0;
>> +	unsigned long time;
>> +
>> +	ret = rtc_tm_to_time(tm, &time);
> 
> 
>> +
>> +	if (ret)
>> +		goto out;
>> +	/*
>> +	 * Setting the RTC time not always succeeds. According to the
>> +	 * errata we need to first write on the status register and
>> +	 * then wait for 1s before writing to the time register to be
>> +	 * sure that the data will be taken into account.
>> +	 */
>> +	writel(0, rtc->regs + RTC_STATUS);
>> +	ssleep(1);
>> +
>> +	writel(time, rtc->regs + RTC_TIME);
> 
> I think writel(time + 1, ...) would correct the one second shift you
> introduce using you ssleep() above.

I will just move the rtc_tm_to_time-) function here, before the second write.


> 
> Additionally, as discussed above, I do not see why you're not protecting
> the write using you spinlock.

Initially the spinlock was around the 2 writel, but you can't have sleep
in a critical section hold by spinlock so I removed it. However it would be
possible to use them around each writel, but I am not sure that it makes sens.

> 
> 
>> +
>> +out:
>> +	return ret;
>> +}
>> +
>> +static int armada38x_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alrm)
>> +{
>> +	struct armada38x_rtc *rtc = dev_get_drvdata(dev);
>> +	unsigned long time, flags;
>> +	u32 val;
>> +
>> +	spin_lock_irqsave(&rtc->lock, flags);
>> +
>> +	time = readl(rtc->regs + RTC_ALARM1);
>> +	val = readl(rtc->regs + RTC_IRQ1_CONF) & RTC_IRQ1_AL_EN;
>> +
>> +	spin_unlock_irqrestore(&rtc->lock, flags);
>> +
>> +	alrm->enabled = val ? 1 : 0;
>> +	rtc_time_to_tm(time,  &alrm->time);
>> +
>> +	return 0;
>> +}
>> +
> 
> In the two functions below, regarding RTC interrupt activation, do you
> need a check that a valid IRQ was passed in the .dts and that
> devm_request_irq() went ok in probe(), i.e. that rtc->irq > 0?

You're right is the irq is not valid, I can even removed these 2 functions
from armada38x_rtc_ops.

> 
>> +static int armada38x_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alrm)
>> +{
>> +	struct armada38x_rtc *rtc = dev_get_drvdata(dev);
>> +	unsigned long time, flags;
>> +	int ret = 0;
>> +	u32 val;
>> +
>> +	ret = rtc_tm_to_time(&alrm->time, &time);
>> +
>> +	if (ret)
>> +		goto out;
>> +
>> +	spin_lock_irqsave(&rtc->lock, flags);
>> +
>> +	rtc_delayed_write(time, rtc, RTC_ALARM1);
>> +
>> +	if (alrm->enabled) {
>> +			rtc_delayed_write(RTC_IRQ1_AL_EN , rtc, RTC_IRQ1_CONF);
>> +			val = readl(rtc->regs_soc + SOC_RTC_INTERRUPT);
>> +		writel(val | SOC_RTC_ALARM1_MASK,
>> +			rtc->regs_soc + SOC_RTC_INTERRUPT);
>> +	}
>> +
>> +	spin_unlock_irqrestore(&rtc->lock, flags);
>> +
>> +out:
>> +	return ret;
>> +}
>> +
>> +static int armada38x_rtc_alarm_irq_enable(struct device *dev,
>> +					 unsigned int enabled)
>> +{
>> +	struct armada38x_rtc *rtc = dev_get_drvdata(dev);
>> +	unsigned long flags;
>> +
>> +	spin_lock_irqsave(&rtc->lock, flags);
>> +
>> +	if (enabled)
>> +		writel(RTC_IRQ1_AL_EN, rtc->regs + RTC_IRQ1_CONF);
>> +	else
>> +		writel(0, rtc->regs + RTC_IRQ1_CONF);
> 
> I find the following more readable, but it is subjective:
> 
> writel(enabled ? RTC_IRQ1_AL_EN : 0, rtc->regs + RTC_IRQ1_CONF);
> 
> 
>> +
>> +	spin_unlock_irqrestore(&rtc->lock, flags);
>> +
>> +	return 0;
>> +}
>> +
>> +static irqreturn_t armada38x_rtc_alarm_irq(int irq, void *data)
>> +{
>> +	struct armada38x_rtc *rtc = data;
>> +	u32 val;
>> +	int event = RTC_IRQF | RTC_AF;
>> +
>> +	dev_dbg(&rtc->rtc_dev->dev, "%s:irq(%d)\n", __func__, irq);
>> +	val = readl(rtc->regs_soc + SOC_RTC_INTERRUPT);
>> +
>> +	spin_lock(&rtc->lock);
>> +
>> +	writel(val & ~SOC_RTC_ALARM1, rtc->regs_soc + SOC_RTC_INTERRUPT);
> 
> Why not putting the readl() above under protection of the spinlock to
> protect a change that could occur between the readl() and the writel()?

Indeed it would be better.

> 
> 
>> +	val = readl(rtc->regs + RTC_IRQ1_CONF);
>> +	/* disable all the interrupts for alarm 1 */
>> +	rtc_delayed_write(0, rtc, RTC_IRQ1_CONF);
>> +	/* Ack the event */
>> +	writel(RTC_STATUS_ALARM1, rtc->regs + RTC_STATUS);
>> +
>> +	spin_unlock(&rtc->lock);
>> +
>> +	if (val & RTC_IRQ1_FREQ_EN) {
>> +		if (val & RTC_IRQ1_FREQ_1HZ)
>> +			event |= RTC_UF;
>> +		else
>> +			event |= RTC_PF;
>> +	}
>> +
>> +	rtc_update_irq(rtc->rtc_dev, 1, event);
>> +
>> +	return IRQ_HANDLED;
>> +}
>> +
>> +static const struct rtc_class_ops armada38x_rtc_ops = {
>> +	.read_time = armada38x_rtc_read_time,
>> +	.set_time = armada38x_rtc_set_time,
>> +	.read_alarm = armada38x_rtc_read_alarm,
>> +	.set_alarm = armada38x_rtc_set_alarm,
>> +	.alarm_irq_enable = armada38x_rtc_alarm_irq_enable,
>> +};
>> +
>> +static __init int armada38x_rtc_probe(struct platform_device *pdev)
>> +{
>> +	struct resource *res;
>> +	struct armada38x_rtc *rtc;
>> +	int ret;
>> +
>> +	rtc = devm_kzalloc(&pdev->dev, sizeof(struct armada38x_rtc),
>> +			    GFP_KERNEL);
>> +	if (!rtc)
>> +		return -ENOMEM;
>> +
>> +	spin_lock_init(&rtc->lock);
>> +
>> +	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
>> +	rtc->regs = devm_ioremap_resource(&pdev->dev, res);
>> +	if (IS_ERR(rtc->regs))
>> +		return PTR_ERR(rtc->regs);
>> +	res = platform_get_resource(pdev, IORESOURCE_MEM, 1);
>> +	rtc->regs_soc = devm_ioremap_resource(&pdev->dev, res);
>> +	if (IS_ERR(rtc->regs_soc))
>> +		return PTR_ERR(rtc->regs_soc);
>> +
>> +	rtc->irq = platform_get_irq(pdev, 0);
>> +
>> +	if (rtc->irq < 0) {
>> +		dev_err(&pdev->dev, "no irq\n");
>> +		return rtc->irq;
>> +	}
>> +	if (devm_request_irq(&pdev->dev, rtc->irq, armada38x_rtc_alarm_irq,
>> +				0, pdev->name, rtc) < 0) {
>> +		dev_warn(&pdev->dev, "Interrupt not available.\n");
>> +		rtc->irq = -1;
>> +	}
>> +	platform_set_drvdata(pdev, rtc);
>> +
>> +	device_init_wakeup(&pdev->dev, 1);
> 
> if devm_request_irq() returns an error, should device_init_wakeup() be
> called? See comment below under armada38x_rtc_suspend().

We should not called it and also set the set_alarm and alarm_irq_enable operation
to NULL.

> 
>> +	rtc->rtc_dev = devm_rtc_device_register(&pdev->dev, pdev->name,
>> +					&armada38x_rtc_ops, THIS_MODULE);
>> +	if (IS_ERR(rtc->rtc_dev)) {
>> +		ret = PTR_ERR(rtc->rtc_dev);
>> +		dev_err(&pdev->dev, "Failed to register RTC device: %d\n", ret);
>> +		if (ret == 0)
>> +			ret = -EINVAL;
> 
> I may be missing something but I do not see how ret can be 0 above
> because the initial check uses IS_ERR() and not IS_ERR_OR_NULL().

Indeed I can remove this. The devm_rtc_device_register won't return NULL.

> 
> 
>> +		return ret;
>> +	}
>> +	return 0;
>> +}
>> +
>> +#ifdef CONFIG_PM_SLEEP
>> +static int armada38x_rtc_suspend(struct device *dev)
>> +{
>> +	if (device_may_wakeup(dev)) {
>> +		struct armada38x_rtc *rtc = dev_get_drvdata(dev);
>> +
>> +		return enable_irq_wake(rtc->irq);
>> +	}
> 
> AFAICT, rtc->irq maybe -1 in the call above. You need to either call
> device_init_wakeup() when devm_request_irq() succeed or check rtc->irq
> is valid in the "if" above.

I won't call  device_init_wakeup()  if rtc->irq is -1.

Thanks,

Gregory

> 
>> +
>> +	return 0;
>> +}
>> +
>> +static int armada38x_rtc_resume(struct device *dev)
>> +{
>> +	if (device_may_wakeup(dev)) {
>> +		struct armada38x_rtc *rtc = dev_get_drvdata(dev);
>> +
>> +		return disable_irq_wake(rtc->irq);
>> +	}
>> +
>> +	return 0;
>> +}
>> +#endif
>> +
>> +static SIMPLE_DEV_PM_OPS(armada38x_rtc_pm_ops,
>> +			 armada38x_rtc_suspend, armada38x_rtc_resume);
>> +
>> +#ifdef CONFIG_OF
>> +static const struct of_device_id armada38x_rtc_of_match_table[] = {
>> +	{ .compatible = "marvell,armada-380-rtc", },
>> +	{}
>> +};
>> +#endif
>> +
>> +static struct platform_driver armada38x_rtc_driver = {
>> +	.driver		= {
>> +		.name	= "armada38x-rtc",
>> +		.pm	= &armada38x_rtc_pm_ops,
>> +		.of_match_table = of_match_ptr(armada38x_rtc_of_match_table),
>> +	},
>> +};
>> +
>> +module_platform_driver_probe(armada38x_rtc_driver, armada38x_rtc_probe);
>> +
>> +MODULE_DESCRIPTION("Marvell Armada 38x RTC driver");
>> +MODULE_AUTHOR("Gregory CLEMENT <gregory.clement-wi1+55ScJUtKEb57/3fJTNBPR1lH4CV8@public.gmane.org>");
>> +MODULE_LICENSE("GPL");


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