[PATCH 0/3] Add RTC for MStar SoCs

[PATCH 0/3] Add RTC for MStar SoCs

[Romain Perier]

This patches series adds a new driver for the RTC found in the Mstar
MSC313e SoCs and newer. It adds a basic rtc driver, the corresponding
devicetree bindings and its documentation.

Daniel Palmer (1):
  rtc: Add support for the MSTAR MSC313 RTC

Romain Perier (2):
  dt-bindings: rtc: Add Mstar MSC313e RTC devicetree bindings
    documentation
  ARM: dts: mstar: Add rtc device node

 .../bindings/rtc/mstar,msc313-rtc.yaml        |  46 ++++
 MAINTAINERS                                   |   1 +
 arch/arm/boot/dts/mstar-v7.dtsi               |   7 +
 drivers/rtc/Kconfig                           |  10 +
 drivers/rtc/Makefile                          |   1 +
 drivers/rtc/rtc-msc313.c                      | 246 ++++++++++++++++++
 6 files changed, 311 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/rtc/mstar,msc313-rtc.yaml
 create mode 100644 drivers/rtc/rtc-msc313.c

-- 
2.30.2

[PATCH 1/3] dt-bindings: rtc: Add Mstar MSC313e RTC devicetree bindings documentation

[Romain Perier]

This adds the documentation for the devicetree bindings of the Mstar
MSC313e RTC driver, found from MSC313e SoCs and newer.

Signed-off-by: Romain Perier <romain.perier@gmail.com>
---
 .../bindings/rtc/mstar,msc313-rtc.yaml        | 46 +++++++++++++++++++
 1 file changed, 46 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/rtc/mstar,msc313-rtc.yaml

diff --git a/Documentation/devicetree/bindings/rtc/mstar,msc313-rtc.yaml b/Documentation/devicetree/bindings/rtc/mstar,msc313-rtc.yaml
new file mode 100644
index 000000000000..978c28bc3da5
--- /dev/null
+++ b/Documentation/devicetree/bindings/rtc/mstar,msc313-rtc.yaml
@@ -0,0 +1,46 @@
+# SPDX-License-Identifier: GPL-2.0
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/rtc/mstar,msc313-rtc.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Mstar MSC313e RTC Device Tree Bindings
+
+allOf:
+  - $ref: "rtc.yaml#"
+
+maintainers:
+  - Daniel Palmer <daniel@0x0f.com>
+  - Romain Perier <romain.perier@gmail.com>
+
+properties:
+  compatible:
+    enum:
+      - mstar,msc313-rtc
+
+  reg:
+    maxItems: 1
+
+  interrupts:
+    maxItems: 1
+
+  clocks:
+    maxItems: 1
+
+required:
+  - compatible
+  - reg
+  - interrupts
+  - clocks
+
+additionalProperties: false
+
+examples:
+  - |
+    rtc@2400 {
+        compatible = "mstar,msc313-rtc";
+        reg = <0x2400 0x40>;
+        clocks = <&xtal_div2>;
+        interrupts-extended = <&intc_irq GIC_SPI 44 IRQ_TYPE_LEVEL_HIGH>;
+    };
+...
-- 
2.30.2

[PATCH 2/3] rtc: Add support for the MSTAR MSC313 RTC

[Romain Perier]

From: Daniel Palmer <daniel@0x0f.com>

This adds support for the RTC block on the Mstar MSC313e SoCs and newer.

Signed-off-by: Daniel Palmer <daniel@0x0f.com>
Co-developed-by: Romain Perier <romain.perier@gmail.com>
Signed-off-by: Romain Perier <romain.perier@gmail.com>
---
 MAINTAINERS              |   1 +
 drivers/rtc/Kconfig      |  10 ++
 drivers/rtc/Makefile     |   1 +
 drivers/rtc/rtc-msc313.c | 246 +++++++++++++++++++++++++++++++++++++++
 4 files changed, 258 insertions(+)
 create mode 100644 drivers/rtc/rtc-msc313.c

diff --git a/MAINTAINERS b/MAINTAINERS
index 6c8be735cc91..7e8d1a375e0d 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -2220,6 +2220,7 @@ F:	arch/arm/boot/dts/mstar-*
 F:	arch/arm/mach-mstar/
 F:	drivers/clk/mstar/
 F:	drivers/gpio/gpio-msc313.c
+F:	drivers/rtc/rtc-msc313.c
 F:	drivers/watchdog/msc313e_wdt.c
 F:	include/dt-bindings/clock/mstar-*
 F:	include/dt-bindings/gpio/msc313-gpio.h
diff --git a/drivers/rtc/Kconfig b/drivers/rtc/Kconfig
index 12153d5801ce..67870b422bc5 100644
--- a/drivers/rtc/Kconfig
+++ b/drivers/rtc/Kconfig
@@ -1925,4 +1925,14 @@ config RTC_DRV_WILCO_EC
 	  This can also be built as a module. If so, the module will
 	  be named "rtc_wilco_ec".
 
+config RTC_DRV_MSC313
+	tristate "MStar MSC313 RTC"
+        depends on ARCH_MSTARV7
+	help
+	  If you say yes here you get support for the Mstar MSC313e On-Chip
+	  Real Time Clock.
+
+	  This driver can also be built as a module, if so, the module
+	  will be called "rtc-msc313".
+
 endif # RTC_CLASS
diff --git a/drivers/rtc/Makefile b/drivers/rtc/Makefile
index 2dd0dd956b0e..5efda8a60cee 100644
--- a/drivers/rtc/Makefile
+++ b/drivers/rtc/Makefile
@@ -101,6 +101,7 @@ obj-$(CONFIG_RTC_DRV_MCP795)	+= rtc-mcp795.o
 obj-$(CONFIG_RTC_DRV_MESON)	+= rtc-meson.o
 obj-$(CONFIG_RTC_DRV_MOXART)	+= rtc-moxart.o
 obj-$(CONFIG_RTC_DRV_MPC5121)	+= rtc-mpc5121.o
+obj-$(CONFIG_RTC_DRV_MSC313)	+= rtc-msc313.o
 obj-$(CONFIG_RTC_DRV_MSM6242)	+= rtc-msm6242.o
 obj-$(CONFIG_RTC_DRV_MT2712)	+= rtc-mt2712.o
 obj-$(CONFIG_RTC_DRV_MT6397)	+= rtc-mt6397.o
diff --git a/drivers/rtc/rtc-msc313.c b/drivers/rtc/rtc-msc313.c
new file mode 100644
index 000000000000..b1102e3c93ba
--- /dev/null
+++ b/drivers/rtc/rtc-msc313.c
@@ -0,0 +1,246 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Real time clocks driver for MStar/SigmaStar ARMv7 SoCs.
+ * Based on "Real Time Clock driver for msb252x." that was contained
+ * in various MStar kernels.
+ *
+ * (C) 2019 Daniel Palmer
+ * (C) 2021 Romain Perier
+ */
+
+#include <linux/clk.h>
+#include <linux/delay.h>
+#include <linux/module.h>
+#include <linux/mod_devicetable.h>
+#include <linux/platform_device.h>
+#include <linux/rtc.h>
+
+/* Registers */
+#define REG_RTC_CTRL		0x00
+#define REG_RTC_FREQ_CW_L	0x04
+#define REG_RTC_FREQ_CW_H	0x08
+#define REG_RTC_LOAD_VAL_L	0x0C
+#define REG_RTC_LOAD_VAL_H	0x10
+#define REG_RTC_MATCH_VAL_L	0x14
+#define REG_RTC_MATCH_VAL_H	0x18
+#define REG_RTC_CNT_VAL_L	0x20
+#define REG_RTC_CNT_VAL_H	0x24
+
+#define SOFT_RSTZ_BIT		BIT(0)
+#define CNT_EN_BIT		BIT(1)
+#define WRAP_EN_BIT		BIT(2)
+#define LOAD_EN_BIT		BIT(3)
+#define READ_EN_BIT		BIT(4)
+#define INT_MASK_BIT		BIT(5)
+#define INT_FORCE_BIT		BIT(6)
+#define INT_CLEAR_BIT		BIT(7)
+
+struct msc313_rtc {
+	struct rtc_device *rtc_dev;
+	void __iomem *rtc_base;
+	struct clk *clk;
+};
+
+static int msc313_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alarm)
+{
+	struct msc313_rtc *priv = dev_get_drvdata(dev);
+	unsigned long seconds;
+
+	seconds = readw(priv->rtc_base + REG_RTC_MATCH_VAL_L)
+			| (readw(priv->rtc_base + REG_RTC_MATCH_VAL_H) << 16);
+
+	rtc_time64_to_tm(seconds, &alarm->time);
+
+	if (!(readw(priv->rtc_base + REG_RTC_CTRL) & INT_MASK_BIT))
+		alarm->enabled = 1;
+
+	return 0;
+}
+
+static int msc313_rtc_alarm_irq_enable(struct device *dev, unsigned int enabled)
+{
+	struct msc313_rtc *priv = dev_get_drvdata(dev);
+	u16 reg;
+
+	reg = readw(priv->rtc_base + REG_RTC_CTRL);
+	if (enabled)
+		reg &= ~INT_MASK_BIT;
+	else
+		reg |= INT_MASK_BIT;
+	writew(reg, priv->rtc_base + REG_RTC_CTRL);
+	return 0;
+}
+
+static int msc313_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alarm)
+{
+	struct msc313_rtc *priv = dev_get_drvdata(dev);
+	unsigned long seconds;
+
+	seconds = rtc_tm_to_time64(&alarm->time);
+	writew((seconds & 0xFFFF), priv->rtc_base + REG_RTC_MATCH_VAL_L);
+	writew((seconds >> 16) & 0xFFFF, priv->rtc_base + REG_RTC_MATCH_VAL_H);
+
+	msc313_rtc_alarm_irq_enable(dev, alarm->enabled);
+
+	return 0;
+}
+
+static int msc313_rtc_read_time(struct device *dev, struct rtc_time *tm)
+{
+	struct msc313_rtc *priv = dev_get_drvdata(dev);
+	u32 seconds;
+	u16 reg;
+
+	reg = readw(priv->rtc_base + REG_RTC_CTRL);
+	writew(reg | READ_EN_BIT, priv->rtc_base + REG_RTC_CTRL);
+
+	/* Wait for HW latch done */
+	while (readw(priv->rtc_base + REG_RTC_CTRL) & READ_EN_BIT)
+		udelay(1);
+
+	seconds = readw(priv->rtc_base + REG_RTC_CNT_VAL_L)
+			| (readw(priv->rtc_base + REG_RTC_CNT_VAL_H) << 16);
+
+	rtc_time64_to_tm(seconds, tm);
+
+	return rtc_valid_tm(tm);
+}
+
+static int msc313_rtc_set_time(struct device *dev, struct rtc_time *tm)
+{
+	struct msc313_rtc *priv = dev_get_drvdata(dev);
+	unsigned long seconds;
+	u16 reg;
+
+	seconds = rtc_tm_to_time64(tm);
+	writew(seconds & 0xFFFF, priv->rtc_base + REG_RTC_LOAD_VAL_L);
+	writew((seconds >> 16) & 0xFFFF, priv->rtc_base + REG_RTC_LOAD_VAL_H);
+	reg = readw(priv->rtc_base + REG_RTC_CTRL);
+	writew(reg | LOAD_EN_BIT, priv->rtc_base + REG_RTC_CTRL);
+
+	/* need to check carefully if we want to clear REG_RTC_LOAD_VAL_H for customer*/
+	while (readw(priv->rtc_base + REG_RTC_CTRL) & LOAD_EN_BIT)
+		udelay(1);
+	writew(0, priv->rtc_base + REG_RTC_LOAD_VAL_H);
+
+	return 0;
+}
+
+static const struct rtc_class_ops msc313_rtc_ops = {
+	.read_time = msc313_rtc_read_time,
+	.set_time = msc313_rtc_set_time,
+	.read_alarm = msc313_rtc_read_alarm,
+	.set_alarm = msc313_rtc_set_alarm,
+	.alarm_irq_enable = msc313_rtc_alarm_irq_enable,
+};
+
+static irqreturn_t msc313_rtc_interrupt(s32 irq, void *dev_id)
+{
+	struct msc313_rtc *priv = dev_get_drvdata(dev_id);
+	u16 reg;
+
+	reg = readw_relaxed(priv->rtc_base + REG_RTC_CTRL);
+	reg |= INT_CLEAR_BIT;
+	reg &= ~INT_FORCE_BIT;
+	writew_relaxed(reg, priv->rtc_base + REG_RTC_CTRL);
+
+	rtc_update_irq(priv->rtc_dev, 1, RTC_IRQF | RTC_AF);
+
+	return IRQ_HANDLED;
+}
+
+static int msc313_rtc_remove(struct platform_device *pdev)
+{
+	struct msc313_rtc *priv = platform_get_drvdata(pdev);
+
+	clk_disable_unprepare(priv->clk);
+
+	return 0;
+}
+
+static int msc313_rtc_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct msc313_rtc *priv;
+	int ret;
+	int irq;
+	unsigned long rate;
+	u16 reg;
+
+	priv = devm_kzalloc(&pdev->dev, sizeof(struct msc313_rtc), GFP_KERNEL);
+	if (!priv)
+		return -ENOMEM;
+
+	priv->rtc_base = devm_platform_ioremap_resource(pdev, 0);
+	if (IS_ERR(priv->rtc_base))
+		return PTR_ERR(priv->rtc_base);
+
+	irq = platform_get_irq(pdev, 0);
+	if (irq < 0)
+		return -EINVAL;
+
+	ret = devm_request_irq(dev, irq, msc313_rtc_interrupt, IRQF_SHARED,
+			       dev_name(&pdev->dev), &pdev->dev);
+	if (ret) {
+		dev_err(dev, "Unable to request irq\n");
+		return ret;
+	}
+
+	priv->clk = devm_clk_get(dev, NULL);
+	if (IS_ERR(priv->clk)) {
+		dev_err(dev, "No input reference clock\n");
+		return PTR_ERR(priv->clk);
+	}
+
+	ret = clk_prepare_enable(priv->clk);
+	if (ret) {
+		dev_err(dev, "Failed to enable the reference clock, %d\n", ret);
+		return ret;
+	}
+
+	rate = clk_get_rate(priv->clk);
+
+	reg = readw(priv->rtc_base + REG_RTC_CTRL);
+	if (!(reg & SOFT_RSTZ_BIT)) {
+		reg |= SOFT_RSTZ_BIT;
+		writew(reg, priv->rtc_base + REG_RTC_CTRL);
+	}
+
+	writew(rate & 0xFFFF, priv->rtc_base + REG_RTC_FREQ_CW_L);
+	writew((rate >> 16) & 0xFFFF, priv->rtc_base + REG_RTC_FREQ_CW_H);
+
+	reg |= CNT_EN_BIT;
+	writew(reg, priv->rtc_base + REG_RTC_CTRL);
+
+	platform_set_drvdata(pdev, priv);
+
+	priv->rtc_dev = devm_rtc_device_register(dev, dev_name(dev), &msc313_rtc_ops, THIS_MODULE);
+	if (IS_ERR(priv->rtc_dev)) {
+		dev_err(dev, "Failed to register rtc device\n");
+		return PTR_ERR(priv->rtc_dev);
+	}
+
+	return 0;
+}
+
+static const struct of_device_id msc313_rtc_of_match_table[] = {
+	{ .compatible = "mstar,msc313-rtc" },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, ms_rtc_of_match_table);
+
+static struct platform_driver msc313_rtc_driver = {
+	.remove = msc313_rtc_remove,
+	.probe = msc313_rtc_probe,
+	.driver = {
+		.name = "msc313-rtc",
+		.of_match_table = msc313_rtc_of_match_table,
+	},
+};
+
+module_platform_driver(msc313_rtc_driver);
+
+MODULE_AUTHOR("Daniel Palmer <daniel@thingy.jp>");
+MODULE_AUTHOR("Romain Perier <romain.perier@gmail.com>");
+MODULE_DESCRIPTION("MStar RTC Driver");
+MODULE_LICENSE("GPL v2");
-- 
2.30.2

[PATCH 3/3] ARM: dts: mstar: Add rtc device node

[Romain Perier]

This adds the definition of the rtc device node. The RTC being able to
work with the oscillator at 12Mhz for now, it shares the same xtal than
the watchdog.

Signed-off-by: Romain Perier <romain.perier@gmail.com>
---
 arch/arm/boot/dts/mstar-v7.dtsi | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/arch/arm/boot/dts/mstar-v7.dtsi b/arch/arm/boot/dts/mstar-v7.dtsi
index 982dba9d28eb..1d4419aee67d 100644
--- a/arch/arm/boot/dts/mstar-v7.dtsi
+++ b/arch/arm/boot/dts/mstar-v7.dtsi
@@ -116,6 +116,13 @@ watchdog@6000 {
 				clocks = <&xtal_div2>;
 			};
 
+			rtc@2400 {
+				compatible = "mstar,msc313-rtc";
+				reg = <0x2400 0x40>;
+				clocks = <&xtal_div2>;
+				interrupts-extended = <&intc_irq GIC_SPI 44 IRQ_TYPE_LEVEL_HIGH>;
+			};
+
 			intc_fiq: interrupt-controller@201310 {
 				compatible = "mstar,mst-intc";
 				reg = <0x201310 0x40>;
-- 
2.30.2

Re: [PATCH 2/3] rtc: Add support for the MSTAR MSC313 RTC

[Alexandre Belloni]

Hello Romain,

On 20/07/2021 19:22:50+0200, Romain Perier wrote:
> From: Daniel Palmer <daniel@0x0f.com>
> 
> This adds support for the RTC block on the Mstar MSC313e SoCs and newer.
> 
> Signed-off-by: Daniel Palmer <daniel@0x0f.com>
> Co-developed-by: Romain Perier <romain.perier@gmail.com>
> Signed-off-by: Romain Perier <romain.perier@gmail.com>
> ---
>  MAINTAINERS              |   1 +
>  drivers/rtc/Kconfig      |  10 ++
>  drivers/rtc/Makefile     |   1 +
>  drivers/rtc/rtc-msc313.c | 246 +++++++++++++++++++++++++++++++++++++++
>  4 files changed, 258 insertions(+)
>  create mode 100644 drivers/rtc/rtc-msc313.c
> 
> diff --git a/MAINTAINERS b/MAINTAINERS
> index 6c8be735cc91..7e8d1a375e0d 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -2220,6 +2220,7 @@ F:	arch/arm/boot/dts/mstar-*
>  F:	arch/arm/mach-mstar/
>  F:	drivers/clk/mstar/
>  F:	drivers/gpio/gpio-msc313.c
> +F:	drivers/rtc/rtc-msc313.c
>  F:	drivers/watchdog/msc313e_wdt.c
>  F:	include/dt-bindings/clock/mstar-*
>  F:	include/dt-bindings/gpio/msc313-gpio.h
> diff --git a/drivers/rtc/Kconfig b/drivers/rtc/Kconfig
> index 12153d5801ce..67870b422bc5 100644
> --- a/drivers/rtc/Kconfig
> +++ b/drivers/rtc/Kconfig
> @@ -1925,4 +1925,14 @@ config RTC_DRV_WILCO_EC
>  	  This can also be built as a module. If so, the module will
>  	  be named "rtc_wilco_ec".
>  
> +config RTC_DRV_MSC313
> +	tristate "MStar MSC313 RTC"
> +        depends on ARCH_MSTARV7

|| COMPILE_TEST maybe ?

> +	help
> +	  If you say yes here you get support for the Mstar MSC313e On-Chip
> +	  Real Time Clock.
> +
> +	  This driver can also be built as a module, if so, the module
> +	  will be called "rtc-msc313".
> +
>  endif # RTC_CLASS


> +static int msc313_rtc_read_time(struct device *dev, struct rtc_time *tm)
> +{
> +	struct msc313_rtc *priv = dev_get_drvdata(dev);
> +	u32 seconds;
> +	u16 reg;
> +
> +	reg = readw(priv->rtc_base + REG_RTC_CTRL);
> +	writew(reg | READ_EN_BIT, priv->rtc_base + REG_RTC_CTRL);
> +
> +	/* Wait for HW latch done */
> +	while (readw(priv->rtc_base + REG_RTC_CTRL) & READ_EN_BIT)
> +		udelay(1);
> +
> +	seconds = readw(priv->rtc_base + REG_RTC_CNT_VAL_L)
> +			| (readw(priv->rtc_base + REG_RTC_CNT_VAL_H) << 16);
> +
> +	rtc_time64_to_tm(seconds, tm);
> +
> +	return rtc_valid_tm(tm);

This is not necessary, tm is valid at that point (and the core will
check anyway).

> +}
> +
> +static int msc313_rtc_set_time(struct device *dev, struct rtc_time *tm)
> +{
> +	struct msc313_rtc *priv = dev_get_drvdata(dev);
> +	unsigned long seconds;
> +	u16 reg;
> +
> +	seconds = rtc_tm_to_time64(tm);
> +	writew(seconds & 0xFFFF, priv->rtc_base + REG_RTC_LOAD_VAL_L);
> +	writew((seconds >> 16) & 0xFFFF, priv->rtc_base + REG_RTC_LOAD_VAL_H);
> +	reg = readw(priv->rtc_base + REG_RTC_CTRL);
> +	writew(reg | LOAD_EN_BIT, priv->rtc_base + REG_RTC_CTRL);
> +
> +	/* need to check carefully if we want to clear REG_RTC_LOAD_VAL_H for customer*/
> +	while (readw(priv->rtc_base + REG_RTC_CTRL) & LOAD_EN_BIT)
> +		udelay(1);
> +	writew(0, priv->rtc_base + REG_RTC_LOAD_VAL_H);

Why is that necessary? The comment is not super useful here.

> +
> +	return 0;
> +}
> +
> +static const struct rtc_class_ops msc313_rtc_ops = {
> +	.read_time = msc313_rtc_read_time,
> +	.set_time = msc313_rtc_set_time,
> +	.read_alarm = msc313_rtc_read_alarm,
> +	.set_alarm = msc313_rtc_set_alarm,
> +	.alarm_irq_enable = msc313_rtc_alarm_irq_enable,
> +};
> +
> +static irqreturn_t msc313_rtc_interrupt(s32 irq, void *dev_id)
> +{
> +	struct msc313_rtc *priv = dev_get_drvdata(dev_id);
> +	u16 reg;
> +
> +	reg = readw_relaxed(priv->rtc_base + REG_RTC_CTRL);
> +	reg |= INT_CLEAR_BIT;
> +	reg &= ~INT_FORCE_BIT;
> +	writew_relaxed(reg, priv->rtc_base + REG_RTC_CTRL);
> +

I'm not convinced the _relaxed functions are doing the right thing here.
Also, shouldn't you check the alarm actually fired?

> +	rtc_update_irq(priv->rtc_dev, 1, RTC_IRQF | RTC_AF);
> +
> +	return IRQ_HANDLED;
> +}
> +
> +static int msc313_rtc_remove(struct platform_device *pdev)
> +{
> +	struct msc313_rtc *priv = platform_get_drvdata(pdev);
> +
> +	clk_disable_unprepare(priv->clk);

With a nice devm_add_action_or_reset() in the probe, you can remove the
need for msc313_rtc_remove().

> +
> +	return 0;
> +}
> +
> +static int msc313_rtc_probe(struct platform_device *pdev)
> +{
> +	struct device *dev = &pdev->dev;
> +	struct msc313_rtc *priv;
> +	int ret;
> +	int irq;
> +	unsigned long rate;
> +	u16 reg;
> +
> +	priv = devm_kzalloc(&pdev->dev, sizeof(struct msc313_rtc), GFP_KERNEL);
> +	if (!priv)
> +		return -ENOMEM;
> +
> +	priv->rtc_base = devm_platform_ioremap_resource(pdev, 0);
> +	if (IS_ERR(priv->rtc_base))
> +		return PTR_ERR(priv->rtc_base);
> +
> +	irq = platform_get_irq(pdev, 0);
> +	if (irq < 0)
> +		return -EINVAL;
> +
> +	ret = devm_request_irq(dev, irq, msc313_rtc_interrupt, IRQF_SHARED,
> +			       dev_name(&pdev->dev), &pdev->dev);
> +	if (ret) {
> +		dev_err(dev, "Unable to request irq\n");
> +		return ret;
> +	}
> +
> +	priv->clk = devm_clk_get(dev, NULL);
> +	if (IS_ERR(priv->clk)) {
> +		dev_err(dev, "No input reference clock\n");
> +		return PTR_ERR(priv->clk);
> +	}
> +
> +	ret = clk_prepare_enable(priv->clk);
> +	if (ret) {
> +		dev_err(dev, "Failed to enable the reference clock, %d\n", ret);
> +		return ret;
> +	}
> +
> +	rate = clk_get_rate(priv->clk);
> +
> +	reg = readw(priv->rtc_base + REG_RTC_CTRL);
> +	if (!(reg & SOFT_RSTZ_BIT)) {
> +		reg |= SOFT_RSTZ_BIT;
> +		writew(reg, priv->rtc_base + REG_RTC_CTRL);
> +	}

What is the meaning of this bit? I would think it is better to use that
to know whether the RTC holds the correct time instead of killing the
info here.

> +
> +	writew(rate & 0xFFFF, priv->rtc_base + REG_RTC_FREQ_CW_L);
> +	writew((rate >> 16) & 0xFFFF, priv->rtc_base + REG_RTC_FREQ_CW_H);
> +
> +	reg |= CNT_EN_BIT;
> +	writew(reg, priv->rtc_base + REG_RTC_CTRL);
> +
> +	platform_set_drvdata(pdev, priv);
> +
> +	priv->rtc_dev = devm_rtc_device_register(dev, dev_name(dev), &msc313_rtc_ops, THIS_MODULE);
> +	if (IS_ERR(priv->rtc_dev)) {
> +		dev_err(dev, "Failed to register rtc device\n");
> +		return PTR_ERR(priv->rtc_dev);
> +	}

Please switch to devm_rtc_allocate_device and devm_rtc_register_device.
Also drop the error message, it is not necessary.

You must also set the RTC range. To help you, you can use:
https://git.kernel.org/pub/scm/linux/kernel/git/abelloni/rtc-tools.git/tree/rtc-range.c
then you must update the DT bindings as the RTC will support the
start-year property

You must also run rtctest and should include the results.


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

Re: [PATCH 1/3] dt-bindings: rtc: Add Mstar MSC313e RTC devicetree bindings documentation

[Rob Herring]

On Tue, 20 Jul 2021 19:22:49 +0200, Romain Perier wrote:
> This adds the documentation for the devicetree bindings of the Mstar
> MSC313e RTC driver, found from MSC313e SoCs and newer.
> 
> Signed-off-by: Romain Perier <romain.perier@gmail.com>
> ---
>  .../bindings/rtc/mstar,msc313-rtc.yaml        | 46 +++++++++++++++++++
>  1 file changed, 46 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/rtc/mstar,msc313-rtc.yaml
> 

My bot found errors running 'make DT_CHECKER_FLAGS=-m dt_binding_check'
on your patch (DT_CHECKER_FLAGS is new in v5.13):

yamllint warnings/errors:

dtschema/dtc warnings/errors:
Error: Documentation/devicetree/bindings/rtc/mstar,msc313-rtc.example.dts:23.46-47 syntax error
FATAL ERROR: Unable to parse input tree
make[1]: *** [scripts/Makefile.lib:380: Documentation/devicetree/bindings/rtc/mstar,msc313-rtc.example.dt.yaml] Error 1
make[1]: *** Waiting for unfinished jobs....
make: *** [Makefile:1418: dt_binding_check] Error 2
\ndoc reference errors (make refcheckdocs):

See https://patchwork.ozlabs.org/patch/1507685

This check can fail if there are any dependencies. The base for a patch
series is generally the most recent rc1.

If you already ran 'make dt_binding_check' and didn't see the above
error(s), then make sure 'yamllint' is installed and dt-schema is up to
date:

pip3 install dtschema --upgrade

Please check and re-submit.

Re: [PATCH 2/3] rtc: Add support for the MSTAR MSC313 RTC

[Romain Perier]

Hello Alexandre,

Le mar. 20 juil. 2021 à 22:01, Alexandre Belloni
<alexandre.belloni@bootlin.com> a écrit :
>
> Hello Romain,
>
> On 20/07/2021 19:22:50+0200, Romain Perier wrote:
> > From: Daniel Palmer <daniel@0x0f.com>
> >
> > This adds support for the RTC block on the Mstar MSC313e SoCs and newer.
> >
> > Signed-off-by: Daniel Palmer <daniel@0x0f.com>
> > Co-developed-by: Romain Perier <romain.perier@gmail.com>
> > Signed-off-by: Romain Perier <romain.perier@gmail.com>
> > ---
> >  MAINTAINERS              |   1 +
> >  drivers/rtc/Kconfig      |  10 ++
> >  drivers/rtc/Makefile     |   1 +
> >  drivers/rtc/rtc-msc313.c | 246 +++++++++++++++++++++++++++++++++++++++
> >  4 files changed, 258 insertions(+)
> >  create mode 100644 drivers/rtc/rtc-msc313.c
> >
> > diff --git a/MAINTAINERS b/MAINTAINERS
> > index 6c8be735cc91..7e8d1a375e0d 100644
> > --- a/MAINTAINERS
> > +++ b/MAINTAINERS
> > @@ -2220,6 +2220,7 @@ F:      arch/arm/boot/dts/mstar-*
> >  F:   arch/arm/mach-mstar/
> >  F:   drivers/clk/mstar/
> >  F:   drivers/gpio/gpio-msc313.c
> > +F:   drivers/rtc/rtc-msc313.c
> >  F:   drivers/watchdog/msc313e_wdt.c
> >  F:   include/dt-bindings/clock/mstar-*
> >  F:   include/dt-bindings/gpio/msc313-gpio.h
> > diff --git a/drivers/rtc/Kconfig b/drivers/rtc/Kconfig
> > index 12153d5801ce..67870b422bc5 100644
> > --- a/drivers/rtc/Kconfig
> > +++ b/drivers/rtc/Kconfig
> > @@ -1925,4 +1925,14 @@ config RTC_DRV_WILCO_EC
> >         This can also be built as a module. If so, the module will
> >         be named "rtc_wilco_ec".
> >
> > +config RTC_DRV_MSC313
> > +     tristate "MStar MSC313 RTC"
> > +        depends on ARCH_MSTARV7
>
> || COMPILE_TEST maybe ?

Arf, I always forget this option. Ack, I will add it in v2.

>
> > +     help
> > +       If you say yes here you get support for the Mstar MSC313e On-Chip
> > +       Real Time Clock.
> > +
> > +       This driver can also be built as a module, if so, the module
> > +       will be called "rtc-msc313".
> > +
> >  endif # RTC_CLASS
>
>
> > +static int msc313_rtc_read_time(struct device *dev, struct rtc_time *tm)
> > +{
> > +     struct msc313_rtc *priv = dev_get_drvdata(dev);
> > +     u32 seconds;
> > +     u16 reg;
> > +
> > +     reg = readw(priv->rtc_base + REG_RTC_CTRL);
> > +     writew(reg | READ_EN_BIT, priv->rtc_base + REG_RTC_CTRL);
> > +
> > +     /* Wait for HW latch done */
> > +     while (readw(priv->rtc_base + REG_RTC_CTRL) & READ_EN_BIT)
> > +             udelay(1);
> > +
> > +     seconds = readw(priv->rtc_base + REG_RTC_CNT_VAL_L)
> > +                     | (readw(priv->rtc_base + REG_RTC_CNT_VAL_H) << 16);
> > +
> > +     rtc_time64_to_tm(seconds, tm);
> > +
> > +     return rtc_valid_tm(tm);
>
> This is not necessary, tm is valid at that point (and the core will
> check anyway).

ack.

>
> > +}
> > +
> > +static int msc313_rtc_set_time(struct device *dev, struct rtc_time *tm)
> > +{
> > +     struct msc313_rtc *priv = dev_get_drvdata(dev);
> > +     unsigned long seconds;
> > +     u16 reg;
> > +
> > +     seconds = rtc_tm_to_time64(tm);
> > +     writew(seconds & 0xFFFF, priv->rtc_base + REG_RTC_LOAD_VAL_L);
> > +     writew((seconds >> 16) & 0xFFFF, priv->rtc_base + REG_RTC_LOAD_VAL_H);
> > +     reg = readw(priv->rtc_base + REG_RTC_CTRL);
> > +     writew(reg | LOAD_EN_BIT, priv->rtc_base + REG_RTC_CTRL);
> > +
> > +     /* need to check carefully if we want to clear REG_RTC_LOAD_VAL_H for customer*/
> > +     while (readw(priv->rtc_base + REG_RTC_CTRL) & LOAD_EN_BIT)
> > +             udelay(1);
> > +     writew(0, priv->rtc_base + REG_RTC_LOAD_VAL_H);
>
> Why is that necessary? The comment is not super useful here.
>
> > +
> > +     return 0;
> > +}
> > +
> > +static const struct rtc_class_ops msc313_rtc_ops = {
> > +     .read_time = msc313_rtc_read_time,
> > +     .set_time = msc313_rtc_set_time,
> > +     .read_alarm = msc313_rtc_read_alarm,
> > +     .set_alarm = msc313_rtc_set_alarm,
> > +     .alarm_irq_enable = msc313_rtc_alarm_irq_enable,
> > +};
> > +
> > +static irqreturn_t msc313_rtc_interrupt(s32 irq, void *dev_id)
> > +{
> > +     struct msc313_rtc *priv = dev_get_drvdata(dev_id);
> > +     u16 reg;
> > +
> > +     reg = readw_relaxed(priv->rtc_base + REG_RTC_CTRL);
> > +     reg |= INT_CLEAR_BIT;
> > +     reg &= ~INT_FORCE_BIT;
> > +     writew_relaxed(reg, priv->rtc_base + REG_RTC_CTRL);
> > +
>
> I'm not convinced the _relaxed functions are doing the right thing here.


Good catch for the _relaxed, I did not pay attention during refactoring.

> Also, shouldn't you check the alarm actually fired?

You mean before set the flag "RTC_AF" ? This driver is mostly based on
reverse engineering,
even if we have some hardware info. I will try to find if it is
possible (I mean,  from the info
I have).

>
> > +     rtc_update_irq(priv->rtc_dev, 1, RTC_IRQF | RTC_AF);
> > +
> > +     return IRQ_HANDLED;
> > +}
> > +
> > +static int msc313_rtc_remove(struct platform_device *pdev)
> > +{
> > +     struct msc313_rtc *priv = platform_get_drvdata(pdev);
> > +
> > +     clk_disable_unprepare(priv->clk);
>
> With a nice devm_add_action_or_reset() in the probe, you can remove the
> need for msc313_rtc_remove().

devm_add_action_or_reset() you said, interesting I did not know this function.


>
> > +
> > +     return 0;
> > +}
> > +
> > +static int msc313_rtc_probe(struct platform_device *pdev)
> > +{
> > +     struct device *dev = &pdev->dev;
> > +     struct msc313_rtc *priv;
> > +     int ret;
> > +     int irq;
> > +     unsigned long rate;
> > +     u16 reg;
> > +
> > +     priv = devm_kzalloc(&pdev->dev, sizeof(struct msc313_rtc), GFP_KERNEL);
> > +     if (!priv)
> > +             return -ENOMEM;
> > +
> > +     priv->rtc_base = devm_platform_ioremap_resource(pdev, 0);
> > +     if (IS_ERR(priv->rtc_base))
> > +             return PTR_ERR(priv->rtc_base);
> > +
> > +     irq = platform_get_irq(pdev, 0);
> > +     if (irq < 0)
> > +             return -EINVAL;
> > +
> > +     ret = devm_request_irq(dev, irq, msc313_rtc_interrupt, IRQF_SHARED,
> > +                            dev_name(&pdev->dev), &pdev->dev);
> > +     if (ret) {
> > +             dev_err(dev, "Unable to request irq\n");
> > +             return ret;
> > +     }
> > +
> > +     priv->clk = devm_clk_get(dev, NULL);
> > +     if (IS_ERR(priv->clk)) {
> > +             dev_err(dev, "No input reference clock\n");
> > +             return PTR_ERR(priv->clk);
> > +     }
> > +
> > +     ret = clk_prepare_enable(priv->clk);
> > +     if (ret) {
> > +             dev_err(dev, "Failed to enable the reference clock, %d\n", ret);
> > +             return ret;
> > +     }
> > +
> > +     rate = clk_get_rate(priv->clk);
> > +
> > +     reg = readw(priv->rtc_base + REG_RTC_CTRL);
> > +     if (!(reg & SOFT_RSTZ_BIT)) {
> > +             reg |= SOFT_RSTZ_BIT;
> > +             writew(reg, priv->rtc_base + REG_RTC_CTRL);
> > +     }
>
> What is the meaning of this bit? I would think it is better to use that
> to know whether the RTC holds the correct time instead of killing the
> info here.
>
> > +
> > +     writew(rate & 0xFFFF, priv->rtc_base + REG_RTC_FREQ_CW_L);
> > +     writew((rate >> 16) & 0xFFFF, priv->rtc_base + REG_RTC_FREQ_CW_H);
> > +
> > +     reg |= CNT_EN_BIT;
> > +     writew(reg, priv->rtc_base + REG_RTC_CTRL);
> > +
> > +     platform_set_drvdata(pdev, priv);
> > +
> > +     priv->rtc_dev = devm_rtc_device_register(dev, dev_name(dev), &msc313_rtc_ops, THIS_MODULE);
> > +     if (IS_ERR(priv->rtc_dev)) {
> > +             dev_err(dev, "Failed to register rtc device\n");
> > +             return PTR_ERR(priv->rtc_dev);
> > +     }
>
> Please switch to devm_rtc_allocate_device and devm_rtc_register_device.
> Also drop the error message, it is not necessary.
>
> You must also set the RTC range. To help you, you can use:
> https://git.kernel.org/pub/scm/linux/kernel/git/abelloni/rtc-tools.git/tree/rtc-range.c
> then you must update the DT bindings as the RTC will support the
> start-year property
>
> You must also run rtctest and should include the results.

Ack, I will do this in v2.

Thanks!