[PATCH V3 1/2] dt-bindings: rtc: zynqmp: Add clock information

[PATCH V3 1/2] dt-bindings: rtc: zynqmp: Add clock information

[Srinivas Neeli]

Added clock information and deprecated calibration support.

Signed-off-by: Srinivas Neeli <srinivas.neeli@xilinx.com>
---
Changes in V3:
-New patch
---
 .../bindings/rtc/xlnx,zynqmp-rtc.yaml         | 20 +++++++++----------
 1 file changed, 10 insertions(+), 10 deletions(-)

diff --git a/Documentation/devicetree/bindings/rtc/xlnx,zynqmp-rtc.yaml b/Documentation/devicetree/bindings/rtc/xlnx,zynqmp-rtc.yaml
index bdb72d3ddf2a..7e87bc1ef9df 100644
--- a/Documentation/devicetree/bindings/rtc/xlnx,zynqmp-rtc.yaml
+++ b/Documentation/devicetree/bindings/rtc/xlnx,zynqmp-rtc.yaml
@@ -26,20 +26,19 @@ properties:
   interrupts:
     minItems: 2
 
+  clocks:
+    items:
+      - description: rtc_clk is the operating frequency of crystal.
+
+  clock-names:
+    items:
+      - const: "rtc_clk"
+
   interrupt-names:
     items:
       - const: alarm
       - const: sec
 
-  calibration:
-    description: |
-      calibration value for 1 sec period which will
-      be programmed directly to calibration register.
-    $ref: /schemas/types.yaml#/definitions/uint32
-    minimum: 0x1
-    maximum: 0x1FFFFF
-    default: 0x198233
-
 required:
   - compatible
   - reg
@@ -60,6 +59,7 @@ examples:
         interrupt-parent = <&gic>;
         interrupts = <0 26 4>, <0 27 4>;
         interrupt-names = "alarm", "sec";
-        calibration = <0x198233>;
+        clock-names = "rtc_clk";
+        clocks = <&rtc_clk>;
       };
     };
-- 
2.17.1

[PATCH V3 2/2] rtc: zynqmp: Add calibration set and get support

[Srinivas Neeli]

Zynqmp RTC controller has a calibration feature to compensate
time deviation due to input clock inaccuracy.
Set and get calibration API's are used for setting and getting
calibration value from the controller calibration register.

Signed-off-by: Srinivas Neeli <srinivas.neeli@xilinx.com>
---
Changes in V3:
 -Calculated tick_mult using crystal frequency.
 -Calibration register updating based on crystal frequency in probe.
 -Supressed MIN an MAX calibration values,Will send separate patch in future.
Changes in V2:
 -Removed unused macro.
 -Updated code with review comments.
---
 drivers/rtc/rtc-zynqmp.c | 104 +++++++++++++++++++++++++++++++--------
 1 file changed, 84 insertions(+), 20 deletions(-)

diff --git a/drivers/rtc/rtc-zynqmp.c b/drivers/rtc/rtc-zynqmp.c
index f440bb52be92..eb6ee55ca725 100644
--- a/drivers/rtc/rtc-zynqmp.c
+++ b/drivers/rtc/rtc-zynqmp.c
@@ -6,6 +6,7 @@
  *
  */
 
+#include <linux/clk.h>
 #include <linux/delay.h>
 #include <linux/init.h>
 #include <linux/io.h>
@@ -36,17 +37,21 @@
 #define RTC_OSC_EN		BIT(24)
 #define RTC_BATT_EN		BIT(31)
 
-#define RTC_CALIB_DEF		0x198233
+#define RTC_CALIB_DEF		0x8000
 #define RTC_CALIB_MASK		0x1FFFFF
 #define RTC_ALRM_MASK          BIT(1)
 #define RTC_MSEC               1000
+#define RTC_FR_MASK		0xF0000
+#define RTC_FR_MAX_TICKS	16
+#define RTC_PPB			1000000000LL
 
 struct xlnx_rtc_dev {
 	struct rtc_device	*rtc;
 	void __iomem		*reg_base;
 	int			alarm_irq;
 	int			sec_irq;
-	unsigned int		calibval;
+	struct clk		*rtc_clk;
+	unsigned int		freq;
 };
 
 static int xlnx_rtc_set_time(struct device *dev, struct rtc_time *tm)
@@ -61,13 +66,6 @@ static int xlnx_rtc_set_time(struct device *dev, struct rtc_time *tm)
 	 */
 	new_time = rtc_tm_to_time64(tm) + 1;
 
-	/*
-	 * Writing into calibration register will clear the Tick Counter and
-	 * force the next second to be signaled exactly in 1 second period
-	 */
-	xrtcdev->calibval &= RTC_CALIB_MASK;
-	writel(xrtcdev->calibval, (xrtcdev->reg_base + RTC_CALIB_WR));
-
 	writel(new_time, xrtcdev->reg_base + RTC_SET_TM_WR);
 
 	/*
@@ -173,15 +171,71 @@ static void xlnx_init_rtc(struct xlnx_rtc_dev *xrtcdev)
 	rtc_ctrl = readl(xrtcdev->reg_base + RTC_CTRL);
 	rtc_ctrl |= RTC_BATT_EN;
 	writel(rtc_ctrl, xrtcdev->reg_base + RTC_CTRL);
+}
 
-	/*
-	 * Based on crystal freq of 33.330 KHz
-	 * set the seconds counter and enable, set fractions counter
-	 * to default value suggested as per design spec
-	 * to correct RTC delay in frequency over period of time.
+static int xlnx_rtc_read_offset(struct device *dev, long *offset)
+{
+	struct xlnx_rtc_dev *xrtcdev = dev_get_drvdata(dev);
+	long offset_val = 0;
+	unsigned int tick_mult = RTC_PPB / xrtcdev->freq;
+	unsigned int calibval;
+
+	calibval = readl(xrtcdev->reg_base + RTC_CALIB_RD);
+	/* Offset with seconds ticks */
+	offset_val = calibval & RTC_TICK_MASK;
+	offset_val = offset_val - RTC_CALIB_DEF;
+	offset_val = offset_val * tick_mult;
+
+	/* Offset with fractional ticks */
+	if (calibval & RTC_FR_EN)
+		offset_val += ((calibval & RTC_FR_MASK) >> RTC_FR_DATSHIFT)
+			* (tick_mult / RTC_FR_MAX_TICKS);
+	*offset = offset_val;
+
+	return 0;
+}
+
+static int xlnx_rtc_set_offset(struct device *dev, long offset)
+{
+	struct xlnx_rtc_dev *xrtcdev = dev_get_drvdata(dev);
+	short int  max_tick;
+	unsigned char fract_tick = 0;
+	unsigned int calibval;
+	int fract_offset;
+	unsigned int tick_mult = RTC_PPB / xrtcdev->freq;
+
+	/* Number ticks for given offset */
+	max_tick = div_s64_rem(offset, tick_mult, &fract_offset);
+
+	/* Number fractional ticks for given offset */
+	if (fract_offset) {
+		if (fract_offset < 0) {
+			fract_offset = fract_offset + tick_mult;
+			max_tick--;
+		}
+		if (fract_offset > (tick_mult / RTC_FR_MAX_TICKS)) {
+			for (fract_tick = 1; fract_tick < 16; fract_tick++) {
+				if (fract_offset <=
+				    (fract_tick *
+				     (tick_mult / RTC_FR_MAX_TICKS)))
+					break;
+			}
+		}
+	}
+
+	/* Zynqmp RTC uses second and fractional tick
+	 * counters for compensation
 	 */
-	xrtcdev->calibval &= RTC_CALIB_MASK;
-	writel(xrtcdev->calibval, (xrtcdev->reg_base + RTC_CALIB_WR));
+	calibval = max_tick + RTC_CALIB_DEF;
+
+	if (fract_tick)
+		calibval |= RTC_FR_EN;
+
+	calibval |= (fract_tick << RTC_FR_DATSHIFT);
+
+	writel(calibval, (xrtcdev->reg_base + RTC_CALIB_WR));
+
+	return 0;
 }
 
 static const struct rtc_class_ops xlnx_rtc_ops = {
@@ -190,6 +244,8 @@ static const struct rtc_class_ops xlnx_rtc_ops = {
 	.read_alarm	  = xlnx_rtc_read_alarm,
 	.set_alarm	  = xlnx_rtc_set_alarm,
 	.alarm_irq_enable = xlnx_rtc_alarm_irq_enable,
+	.read_offset	  = xlnx_rtc_read_offset,
+	.set_offset	  = xlnx_rtc_set_offset,
 };
 
 static irqreturn_t xlnx_rtc_interrupt(int irq, void *id)
@@ -255,10 +311,18 @@ static int xlnx_rtc_probe(struct platform_device *pdev)
 		return ret;
 	}
 
-	ret = of_property_read_u32(pdev->dev.of_node, "calibration",
-				   &xrtcdev->calibval);
-	if (ret)
-		xrtcdev->calibval = RTC_CALIB_DEF;
+	/* Getting the rtc_clk info */
+	xrtcdev->rtc_clk = devm_clk_get_optional(&pdev->dev, "rtc_clk");
+	if (IS_ERR(xrtcdev->rtc_clk)) {
+		if (PTR_ERR(xrtcdev->rtc_clk) != -EPROBE_DEFER)
+			dev_warn(&pdev->dev, "Device clock not found.\n");
+	}
+	xrtcdev->freq = clk_get_rate(xrtcdev->rtc_clk);
+	if (!xrtcdev->freq)
+		xrtcdev->freq = RTC_CALIB_DEF;
+	ret = readl(xrtcdev->reg_base + RTC_CALIB_RD);
+	if (!ret)
+		writel(xrtcdev->freq, (xrtcdev->reg_base + RTC_CALIB_WR));
 
 	xlnx_init_rtc(xrtcdev);
 
-- 
2.17.1

RE: [PATCH V3 1/2] dt-bindings: rtc: zynqmp: Add clock information

[Radhey Shyam Pandey]

> -----Original Message-----
> From: Srinivas Neeli <srinivas.neeli@xilinx.com>
> Sent: Tuesday, November 30, 2021 11:26 AM
> To: a.zummo@towertech.it; alexandre.belloni@bootlin.com; Michal Simek
> <michals@xilinx.com>; Srinivas Goud <sgoud@xilinx.com>; Shubhrajyoti Datta
> <shubhraj@xilinx.com>; Radhey Shyam Pandey <radheys@xilinx.com>
> Cc: linux-rtc@vger.kernel.org; linux-arm-kernel@lists.infradead.org; linux-
> kernel@vger.kernel.org; git <git@xilinx.com>; Srinivas Neeli
> <sneeli@xilinx.com>
> Subject: [PATCH V3 1/2] dt-bindings: rtc: zynqmp: Add clock information
> 
> Added clock information and deprecated calibration support.

Better to also add some background for this change.
> 
> Signed-off-by: Srinivas Neeli <srinivas.neeli@xilinx.com>

Please add Rob and DT mailing list.

./scripts/get_maintainer.pl <.patch>
> ---
> Changes in V3:
> -New patch
> ---
>  .../bindings/rtc/xlnx,zynqmp-rtc.yaml         | 20 +++++++++----------
>  1 file changed, 10 insertions(+), 10 deletions(-)
> 
> diff --git a/Documentation/devicetree/bindings/rtc/xlnx,zynqmp-rtc.yaml
> b/Documentation/devicetree/bindings/rtc/xlnx,zynqmp-rtc.yaml
> index bdb72d3ddf2a..7e87bc1ef9df 100644
> --- a/Documentation/devicetree/bindings/rtc/xlnx,zynqmp-rtc.yaml
> +++ b/Documentation/devicetree/bindings/rtc/xlnx,zynqmp-rtc.yaml
> @@ -26,20 +26,19 @@ properties:
>    interrupts:
>      minItems: 2
> 
> +  clocks:
> +    items:
> +      - description: rtc_clk is the operating frequency of crystal.
> +
> +  clock-names:
> +    items:
> +      - const: "rtc_clk"
> +
>    interrupt-names:
>      items:
>        - const: alarm
>        - const: sec
> 
> -  calibration:

What about existing users for this property?
> -    description: |
> -      calibration value for 1 sec period which will
> -      be programmed directly to calibration register.
> -    $ref: /schemas/types.yaml#/definitions/uint32
> -    minimum: 0x1
> -    maximum: 0x1FFFFF
> -    default: 0x198233
> -
>  required:
>    - compatible
>    - reg
> @@ -60,6 +59,7 @@ examples:
>          interrupt-parent = <&gic>;
>          interrupts = <0 26 4>, <0 27 4>;
>          interrupt-names = "alarm", "sec";
> -        calibration = <0x198233>;
> +        clock-names = "rtc_clk";
> +        clocks = <&rtc_clk>;
>        };
>      };
> --
> 2.17.1

Re: [PATCH V3 1/2] dt-bindings: rtc: zynqmp: Add clock information

[Alexandre Belloni]

Hello Srinivas,

On 30/11/2021 06:37:45+0000, Radhey Shyam Pandey wrote:
> > -----Original Message-----
> > From: Srinivas Neeli <srinivas.neeli@xilinx.com>
> > Sent: Tuesday, November 30, 2021 11:26 AM
> > To: a.zummo@towertech.it; alexandre.belloni@bootlin.com; Michal Simek
> > <michals@xilinx.com>; Srinivas Goud <sgoud@xilinx.com>; Shubhrajyoti Datta
> > <shubhraj@xilinx.com>; Radhey Shyam Pandey <radheys@xilinx.com>
> > Cc: linux-rtc@vger.kernel.org; linux-arm-kernel@lists.infradead.org; linux-
> > kernel@vger.kernel.org; git <git@xilinx.com>; Srinivas Neeli
> > <sneeli@xilinx.com>
> > Subject: [PATCH V3 1/2] dt-bindings: rtc: zynqmp: Add clock information
> > 
> > Added clock information and deprecated calibration support.
> 
> Better to also add some background for this change.
> > 
> > Signed-off-by: Srinivas Neeli <srinivas.neeli@xilinx.com>
> 
> Please add Rob and DT mailing list.
> 

I'm indeed waiting on Rob's review...

> ./scripts/get_maintainer.pl <.patch>
> > ---
> > Changes in V3:
> > -New patch
> > ---
> >  .../bindings/rtc/xlnx,zynqmp-rtc.yaml         | 20 +++++++++----------
> >  1 file changed, 10 insertions(+), 10 deletions(-)
> > 
> > diff --git a/Documentation/devicetree/bindings/rtc/xlnx,zynqmp-rtc.yaml
> > b/Documentation/devicetree/bindings/rtc/xlnx,zynqmp-rtc.yaml
> > index bdb72d3ddf2a..7e87bc1ef9df 100644
> > --- a/Documentation/devicetree/bindings/rtc/xlnx,zynqmp-rtc.yaml
> > +++ b/Documentation/devicetree/bindings/rtc/xlnx,zynqmp-rtc.yaml
> > @@ -26,20 +26,19 @@ properties:
> >    interrupts:
> >      minItems: 2
> > 
> > +  clocks:
> > +    items:
> > +      - description: rtc_clk is the operating frequency of crystal.
> > +
> > +  clock-names:
> > +    items:
> > +      - const: "rtc_clk"
> > +
> >    interrupt-names:
> >      items:
> >        - const: alarm
> >        - const: sec
> > 
> > -  calibration:
> 
> What about existing users for this property?
> > -    description: |
> > -      calibration value for 1 sec period which will
> > -      be programmed directly to calibration register.
> > -    $ref: /schemas/types.yaml#/definitions/uint32
> > -    minimum: 0x1
> > -    maximum: 0x1FFFFF
> > -    default: 0x198233
> > -

I think this needs to stay to mark it as deprecated.

> >  required:
> >    - compatible
> >    - reg
> > @@ -60,6 +59,7 @@ examples:
> >          interrupt-parent = <&gic>;
> >          interrupts = <0 26 4>, <0 27 4>;
> >          interrupt-names = "alarm", "sec";
> > -        calibration = <0x198233>;
> > +        clock-names = "rtc_clk";
> > +        clocks = <&rtc_clk>;
> >        };
> >      };
> > --
> > 2.17.1
> 

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

Re: [PATCH V3 2/2] rtc: zynqmp: Add calibration set and get support

[Alexandre Belloni]

On 30/11/2021 11:25:41+0530, Srinivas Neeli wrote:
> Zynqmp RTC controller has a calibration feature to compensate
> time deviation due to input clock inaccuracy.
> Set and get calibration API's are used for setting and getting
> calibration value from the controller calibration register.
> 
> Signed-off-by: Srinivas Neeli <srinivas.neeli@xilinx.com>
> ---
> Changes in V3:
>  -Calculated tick_mult using crystal frequency.
>  -Calibration register updating based on crystal frequency in probe.
>  -Supressed MIN an MAX calibration values,Will send separate patch in future.

I believe this should go in with this patch and it shouldn't be too
complicated to know whether the calculated value overflows the register.

> Changes in V2:
>  -Removed unused macro.
>  -Updated code with review comments.
> ---
>  drivers/rtc/rtc-zynqmp.c | 104 +++++++++++++++++++++++++++++++--------
>  1 file changed, 84 insertions(+), 20 deletions(-)
> 
> diff --git a/drivers/rtc/rtc-zynqmp.c b/drivers/rtc/rtc-zynqmp.c
> index f440bb52be92..eb6ee55ca725 100644
> --- a/drivers/rtc/rtc-zynqmp.c
> +++ b/drivers/rtc/rtc-zynqmp.c
> @@ -6,6 +6,7 @@
>   *
>   */
>  
> +#include <linux/clk.h>
>  #include <linux/delay.h>
>  #include <linux/init.h>
>  #include <linux/io.h>
> @@ -36,17 +37,21 @@
>  #define RTC_OSC_EN		BIT(24)
>  #define RTC_BATT_EN		BIT(31)
>  
> -#define RTC_CALIB_DEF		0x198233
> +#define RTC_CALIB_DEF		0x8000
>  #define RTC_CALIB_MASK		0x1FFFFF
>  #define RTC_ALRM_MASK          BIT(1)
>  #define RTC_MSEC               1000
> +#define RTC_FR_MASK		0xF0000
> +#define RTC_FR_MAX_TICKS	16
> +#define RTC_PPB			1000000000LL
>  
>  struct xlnx_rtc_dev {
>  	struct rtc_device	*rtc;
>  	void __iomem		*reg_base;
>  	int			alarm_irq;
>  	int			sec_irq;
> -	unsigned int		calibval;
> +	struct clk		*rtc_clk;
> +	unsigned int		freq;
>  };
>  
>  static int xlnx_rtc_set_time(struct device *dev, struct rtc_time *tm)
> @@ -61,13 +66,6 @@ static int xlnx_rtc_set_time(struct device *dev, struct rtc_time *tm)
>  	 */
>  	new_time = rtc_tm_to_time64(tm) + 1;
>  
> -	/*
> -	 * Writing into calibration register will clear the Tick Counter and
> -	 * force the next second to be signaled exactly in 1 second period
> -	 */
> -	xrtcdev->calibval &= RTC_CALIB_MASK;
> -	writel(xrtcdev->calibval, (xrtcdev->reg_base + RTC_CALIB_WR));
> -
>  	writel(new_time, xrtcdev->reg_base + RTC_SET_TM_WR);
>  
>  	/*
> @@ -173,15 +171,71 @@ static void xlnx_init_rtc(struct xlnx_rtc_dev *xrtcdev)
>  	rtc_ctrl = readl(xrtcdev->reg_base + RTC_CTRL);
>  	rtc_ctrl |= RTC_BATT_EN;
>  	writel(rtc_ctrl, xrtcdev->reg_base + RTC_CTRL);
> +}
>  
> -	/*
> -	 * Based on crystal freq of 33.330 KHz
> -	 * set the seconds counter and enable, set fractions counter
> -	 * to default value suggested as per design spec
> -	 * to correct RTC delay in frequency over period of time.
> +static int xlnx_rtc_read_offset(struct device *dev, long *offset)
> +{
> +	struct xlnx_rtc_dev *xrtcdev = dev_get_drvdata(dev);
> +	long offset_val = 0;
> +	unsigned int tick_mult = RTC_PPB / xrtcdev->freq;
> +	unsigned int calibval;
> +
> +	calibval = readl(xrtcdev->reg_base + RTC_CALIB_RD);
> +	/* Offset with seconds ticks */
> +	offset_val = calibval & RTC_TICK_MASK;
> +	offset_val = offset_val - RTC_CALIB_DEF;
> +	offset_val = offset_val * tick_mult;
> +
> +	/* Offset with fractional ticks */
> +	if (calibval & RTC_FR_EN)
> +		offset_val += ((calibval & RTC_FR_MASK) >> RTC_FR_DATSHIFT)
> +			* (tick_mult / RTC_FR_MAX_TICKS);
> +	*offset = offset_val;
> +
> +	return 0;
> +}
> +
> +static int xlnx_rtc_set_offset(struct device *dev, long offset)
> +{
> +	struct xlnx_rtc_dev *xrtcdev = dev_get_drvdata(dev);
> +	short int  max_tick;
> +	unsigned char fract_tick = 0;
> +	unsigned int calibval;
> +	int fract_offset;
> +	unsigned int tick_mult = RTC_PPB / xrtcdev->freq;
> +
> +	/* Number ticks for given offset */
> +	max_tick = div_s64_rem(offset, tick_mult, &fract_offset);
> +
> +	/* Number fractional ticks for given offset */
> +	if (fract_offset) {
> +		if (fract_offset < 0) {
> +			fract_offset = fract_offset + tick_mult;
> +			max_tick--;
> +		}
> +		if (fract_offset > (tick_mult / RTC_FR_MAX_TICKS)) {
> +			for (fract_tick = 1; fract_tick < 16; fract_tick++) {
> +				if (fract_offset <=
> +				    (fract_tick *
> +				     (tick_mult / RTC_FR_MAX_TICKS)))
> +					break;
> +			}
> +		}
> +	}
> +
> +	/* Zynqmp RTC uses second and fractional tick
> +	 * counters for compensation
>  	 */
> -	xrtcdev->calibval &= RTC_CALIB_MASK;
> -	writel(xrtcdev->calibval, (xrtcdev->reg_base + RTC_CALIB_WR));
> +	calibval = max_tick + RTC_CALIB_DEF;
> +
> +	if (fract_tick)
> +		calibval |= RTC_FR_EN;
> +
> +	calibval |= (fract_tick << RTC_FR_DATSHIFT);
> +
> +	writel(calibval, (xrtcdev->reg_base + RTC_CALIB_WR));
> +
> +	return 0;
>  }
>  
>  static const struct rtc_class_ops xlnx_rtc_ops = {
> @@ -190,6 +244,8 @@ static const struct rtc_class_ops xlnx_rtc_ops = {
>  	.read_alarm	  = xlnx_rtc_read_alarm,
>  	.set_alarm	  = xlnx_rtc_set_alarm,
>  	.alarm_irq_enable = xlnx_rtc_alarm_irq_enable,
> +	.read_offset	  = xlnx_rtc_read_offset,
> +	.set_offset	  = xlnx_rtc_set_offset,
>  };
>  
>  static irqreturn_t xlnx_rtc_interrupt(int irq, void *id)
> @@ -255,10 +311,18 @@ static int xlnx_rtc_probe(struct platform_device *pdev)
>  		return ret;
>  	}
>  
> -	ret = of_property_read_u32(pdev->dev.of_node, "calibration",
> -				   &xrtcdev->calibval);
> -	if (ret)
> -		xrtcdev->calibval = RTC_CALIB_DEF;
> +	/* Getting the rtc_clk info */
> +	xrtcdev->rtc_clk = devm_clk_get_optional(&pdev->dev, "rtc_clk");
> +	if (IS_ERR(xrtcdev->rtc_clk)) {
> +		if (PTR_ERR(xrtcdev->rtc_clk) != -EPROBE_DEFER)
> +			dev_warn(&pdev->dev, "Device clock not found.\n");
> +	}
> +	xrtcdev->freq = clk_get_rate(xrtcdev->rtc_clk);
> +	if (!xrtcdev->freq)
> +		xrtcdev->freq = RTC_CALIB_DEF;

Because you changed the value of RTC_CALIB_DEF, I think this breaks
existing DTs.

> +	ret = readl(xrtcdev->reg_base + RTC_CALIB_RD);
> +	if (!ret)
> +		writel(xrtcdev->freq, (xrtcdev->reg_base + RTC_CALIB_WR));
>  
>  	xlnx_init_rtc(xrtcdev);
>  
> -- 
> 2.17.1
> 

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