1 files changed, 114 insertions, 14 deletions

diff --git a/drivers/rtc/rtc-at91rm9200.c b/drivers/rtc/rtc-at91rm9200.c
index 5e811e04cb21..643734dbae33 100644
--- a/drivers/rtc/rtc-at91rm9200.c
+++ b/drivers/rtc/rtc-at91rm9200.c
@@ -22,7 +22,6 @@
 #include <linux/io.h>
 #include <linux/kernel.h>
 #include <linux/module.h>
-#include <linux/of_device.h>
 #include <linux/of.h>
 #include <linux/platform_device.h>
 #include <linux/rtc.h>
@@ -36,6 +35,10 @@
 #define		AT91_RTC_UPDCAL		BIT(1)		/* Update Request Calendar Register */
 
 #define	AT91_RTC_MR		0x04			/* Mode Register */
+#define		AT91_RTC_HRMOD		BIT(0)		/* 12/24 hour mode */
+#define		AT91_RTC_NEGPPM		BIT(4)		/* Negative PPM correction */
+#define		AT91_RTC_CORRECTION	GENMASK(14, 8)	/* Slow clock correction */
+#define		AT91_RTC_HIGHPPM	BIT(15)		/* High PPM correction */
 
 #define	AT91_RTC_TIMR		0x08			/* Time Register */
 #define		AT91_RTC_SEC		GENMASK(6, 0)	/* Current Second */
@@ -77,6 +80,9 @@
 #define		AT91_RTC_NVTIMALR	BIT(2)		/* Non valid Time Alarm */
 #define		AT91_RTC_NVCALALR	BIT(3)		/* Non valid Calendar Alarm */
 
+#define AT91_RTC_CORR_DIVIDEND		3906000
+#define AT91_RTC_CORR_LOW_RATIO		20
+
 #define at91_rtc_read(field) \
 	readl_relaxed(at91_rtc_regs + field)
 #define at91_rtc_write(field, val) \
@@ -84,6 +90,7 @@
 
 struct at91_rtc_config {
 	bool use_shadow_imr;
+	bool has_correction;
 };
 
 static const struct at91_rtc_config *at91_rtc_config;
@@ -122,7 +129,7 @@ static void at91_rtc_write_idr(u32 mask)
 	 *
 	 * Note that there is still a possibility that the mask is updated
 	 * before interrupts have actually been disabled in hardware. The only
-	 * way to be certain would be to poll the IMR-register, which is is
+	 * way to be certain would be to poll the IMR-register, which is
 	 * the very register we are trying to emulate. The register read back
 	 * is a reasonable heuristic.
 	 */
@@ -293,6 +300,75 @@ static int at91_rtc_alarm_irq_enable(struct device *dev, unsigned int enabled)
 	return 0;
 }
 
+static int at91_rtc_readoffset(struct device *dev, long *offset)
+{
+	u32 mr = at91_rtc_read(AT91_RTC_MR);
+	long val = FIELD_GET(AT91_RTC_CORRECTION, mr);
+
+	if (!val) {
+		*offset = 0;
+		return 0;
+	}
+
+	val++;
+
+	if (!(mr & AT91_RTC_NEGPPM))
+		val = -val;
+
+	if (!(mr & AT91_RTC_HIGHPPM))
+		val *= AT91_RTC_CORR_LOW_RATIO;
+
+	*offset = DIV_ROUND_CLOSEST(AT91_RTC_CORR_DIVIDEND, val);
+
+	return 0;
+}
+
+static int at91_rtc_setoffset(struct device *dev, long offset)
+{
+	long corr;
+	u32 mr;
+
+	if (offset > AT91_RTC_CORR_DIVIDEND / 2)
+		return -ERANGE;
+	if (offset < -AT91_RTC_CORR_DIVIDEND / 2)
+		return -ERANGE;
+
+	mr = at91_rtc_read(AT91_RTC_MR);
+	mr &= ~(AT91_RTC_NEGPPM | AT91_RTC_CORRECTION | AT91_RTC_HIGHPPM);
+
+	if (offset > 0)
+		mr |= AT91_RTC_NEGPPM;
+	else
+		offset = -offset;
+
+	/* offset less than 764 ppb, disable correction*/
+	if (offset < 764) {
+		at91_rtc_write(AT91_RTC_MR, mr & ~AT91_RTC_NEGPPM);
+
+		return 0;
+	}
+
+	/*
+	 * 29208 ppb is the perfect cutoff between low range and high range
+	 * low range values are never better than high range value after that.
+	 */
+	if (offset < 29208) {
+		corr = DIV_ROUND_CLOSEST(AT91_RTC_CORR_DIVIDEND, offset * AT91_RTC_CORR_LOW_RATIO);
+	} else {
+		corr = DIV_ROUND_CLOSEST(AT91_RTC_CORR_DIVIDEND, offset);
+		mr |= AT91_RTC_HIGHPPM;
+	}
+
+	if (corr > 128)
+		corr = 128;
+
+	mr |= FIELD_PREP(AT91_RTC_CORRECTION, corr - 1);
+
+	at91_rtc_write(AT91_RTC_MR, mr);
+
+	return 0;
+}
+
 /*
  * IRQ handler for the RTC
  */
@@ -343,6 +419,10 @@ static const struct at91_rtc_config at91sam9x5_config = {
 	.use_shadow_imr	= true,
 };
 
+static const struct at91_rtc_config sama5d4_config = {
+	.has_correction = true,
+};
+
 static const struct of_device_id at91_rtc_dt_ids[] = {
 	{
 		.compatible = "atmel,at91rm9200-rtc",
@@ -352,10 +432,13 @@ static const struct of_device_id at91_rtc_dt_ids[] = {
 		.data = &at91sam9x5_config,
 	}, {
 		.compatible = "atmel,sama5d4-rtc",
-		.data = &at91rm9200_config,
+		.data = &sama5d4_config,
 	}, {
 		.compatible = "atmel,sama5d2-rtc",
-		.data = &at91rm9200_config,
+		.data = &sama5d4_config,
+	}, {
+		.compatible = "microchip,sam9x60-rtc",
+		.data = &sama5d4_config,
 	}, {
 		/* sentinel */
 	}
@@ -370,6 +453,16 @@ static const struct rtc_class_ops at91_rtc_ops = {
 	.alarm_irq_enable = at91_rtc_alarm_irq_enable,
 };
 
+static const struct rtc_class_ops sama5d4_rtc_ops = {
+	.read_time	= at91_rtc_readtime,
+	.set_time	= at91_rtc_settime,
+	.read_alarm	= at91_rtc_readalarm,
+	.set_alarm	= at91_rtc_setalarm,
+	.alarm_irq_enable = at91_rtc_alarm_irq_enable,
+	.set_offset	= at91_rtc_setoffset,
+	.read_offset	= at91_rtc_readoffset,
+};
+
 /*
  * Initialize and install RTC driver
  */
@@ -416,7 +509,7 @@ static int __init at91_rtc_probe(struct platform_device *pdev)
 	}
 
 	at91_rtc_write(AT91_RTC_CR, 0);
-	at91_rtc_write(AT91_RTC_MR, 0);		/* 24 hour mode */
+	at91_rtc_write(AT91_RTC_MR, at91_rtc_read(AT91_RTC_MR) & ~AT91_RTC_HRMOD);
 
 	/* Disable all interrupts */
 	at91_rtc_write_idr(AT91_RTC_ACKUPD | AT91_RTC_ALARM |
@@ -435,12 +528,16 @@ static int __init at91_rtc_probe(struct platform_device *pdev)
 	 * being wake-capable; if it didn't, do that here.
 	 */
 	if (!device_can_wakeup(&pdev->dev))
-		device_init_wakeup(&pdev->dev, 1);
+		device_init_wakeup(&pdev->dev, true);
+
+	if (at91_rtc_config->has_correction)
+		rtc->ops = &sama5d4_rtc_ops;
+	else
+		rtc->ops = &at91_rtc_ops;
 
-	rtc->ops = &at91_rtc_ops;
 	rtc->range_min = RTC_TIMESTAMP_BEGIN_1900;
 	rtc->range_max = RTC_TIMESTAMP_END_2099;
-	ret = rtc_register_device(rtc);
+	ret = devm_rtc_register_device(rtc);
 	if (ret)
 		goto err_clk;
 
@@ -461,7 +558,7 @@ err_clk:
 /*
  * Disable and remove the RTC driver
  */
-static int __exit at91_rtc_remove(struct platform_device *pdev)
+static void __exit at91_rtc_remove(struct platform_device *pdev)
 {
 	/* Disable all interrupts */
 	at91_rtc_write_idr(AT91_RTC_ACKUPD | AT91_RTC_ALARM |
@@ -469,8 +566,6 @@ static int __exit at91_rtc_remove(struct platform_device *pdev)
 					AT91_RTC_CALEV);
 
 	clk_disable_unprepare(sclk);
-
-	return 0;
 }
 
 static void at91_rtc_shutdown(struct platform_device *pdev)
@@ -538,13 +633,19 @@ static int at91_rtc_resume(struct device *dev)
 
 static SIMPLE_DEV_PM_OPS(at91_rtc_pm_ops, at91_rtc_suspend, at91_rtc_resume);
 
-static struct platform_driver at91_rtc_driver = {
+/*
+ * at91_rtc_remove() lives in .exit.text. For drivers registered via
+ * module_platform_driver_probe() this is ok because they cannot get unbound at
+ * runtime. So mark the driver struct with __refdata to prevent modpost
+ * triggering a section mismatch warning.
+ */
+static struct platform_driver at91_rtc_driver __refdata = {
 	.remove		= __exit_p(at91_rtc_remove),
 	.shutdown	= at91_rtc_shutdown,
 	.driver		= {
 		.name	= "at91_rtc",
 		.pm	= &at91_rtc_pm_ops,
-		.of_match_table = of_match_ptr(at91_rtc_dt_ids),
+		.of_match_table = at91_rtc_dt_ids,
 	},
 };
 
@@ -553,4 +654,3 @@ module_platform_driver_probe(at91_rtc_driver, at91_rtc_probe);
 MODULE_AUTHOR("Rick Bronson");
 MODULE_DESCRIPTION("RTC driver for Atmel AT91RM9200");
 MODULE_LICENSE("GPL");
-MODULE_ALIAS("platform:at91_rtc");