rtc: add xilinx zynqmp rtc driver

Add support for RTC controller found on Xilinx Zynq Ultrascale+ MPSoC
platform.
Signed-off-by: Suneel Garapati <suneel.garapati@xilinx.com>
Acked-by: Moritz Fischer <moritz.fischer@ettus.com>
Signed-off-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>

drivers/rtc/Kconfig

@@ -1116,6 +1116,13 @@ config RTC_DRV_OPAL
 	  This driver can also be built as a module. If so, the module
 	  will be called rtc-opal.
 
+config RTC_DRV_ZYNQMP
+	tristate "Xilinx Zynq Ultrascale+ MPSoC RTC"
+	depends on OF
+	help
+	  If you say yes here you get support for the RTC controller found on
+	  Xilinx Zynq Ultrascale+ MPSoC.
+
 comment "on-CPU RTC drivers"
 
 config RTC_DRV_DAVINCI

drivers/rtc/Makefile

@@ -159,3 +159,4 @@ obj-$(CONFIG_RTC_DRV_WM831X)	+= rtc-wm831x.o
 obj-$(CONFIG_RTC_DRV_WM8350)	+= rtc-wm8350.o
 obj-$(CONFIG_RTC_DRV_X1205)	+= rtc-x1205.o
 obj-$(CONFIG_RTC_DRV_XGENE)	+= rtc-xgene.o
+obj-$(CONFIG_RTC_DRV_ZYNQMP)	+= rtc-zynqmp.o

drivers/rtc/rtc-zynqmp.c

+/*
+ * Xilinx Zynq Ultrascale+ MPSoC Real Time Clock Driver
+ *
+ * Copyright (C) 2015 Xilinx, Inc.
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
+ * more details.
+ *
+ * You should have received a copy of the GNU General Public License along with
+ * this program. If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+#include <linux/delay.h>
+#include <linux/init.h>
+#include <linux/io.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/rtc.h>
+
+/* RTC Registers */
+#define RTC_SET_TM_WR		0x00
+#define RTC_SET_TM_RD		0x04
+#define RTC_CALIB_WR		0x08
+#define RTC_CALIB_RD		0x0C
+#define RTC_CUR_TM		0x10
+#define RTC_CUR_TICK		0x14
+#define RTC_ALRM		0x18
+#define RTC_INT_STS		0x20
+#define RTC_INT_MASK		0x24
+#define RTC_INT_EN		0x28
+#define RTC_INT_DIS		0x2C
+#define RTC_CTRL		0x40
+
+#define RTC_FR_EN		BIT(20)
+#define RTC_FR_DATSHIFT		16
+#define RTC_TICK_MASK		0xFFFF
+#define RTC_INT_SEC		BIT(0)
+#define RTC_INT_ALRM		BIT(1)
+#define RTC_OSC_EN		BIT(24)
+
+#define RTC_CALIB_DEF		0x198233
+#define RTC_CALIB_MASK		0x1FFFFF
+#define RTC_SEC_MAX_VAL		0xFFFFFFFF
+
+struct xlnx_rtc_dev {
+	struct rtc_device	*rtc;
+	void __iomem		*reg_base;
+	int			alarm_irq;
+	int			sec_irq;
+};
+
+static int xlnx_rtc_set_time(struct device *dev, struct rtc_time *tm)
+{
+	struct xlnx_rtc_dev *xrtcdev = dev_get_drvdata(dev);
+	unsigned long new_time;
+
+	new_time = rtc_tm_to_time64(tm);
+
+	if (new_time > RTC_SEC_MAX_VAL)
+		return -EINVAL;
+
+	writel(new_time, xrtcdev->reg_base + RTC_SET_TM_WR);
+
+	return 0;
+}
+
+static int xlnx_rtc_read_time(struct device *dev, struct rtc_time *tm)
+{
+	struct xlnx_rtc_dev *xrtcdev = dev_get_drvdata(dev);
+
+	rtc_time64_to_tm(readl(xrtcdev->reg_base + RTC_CUR_TM), tm);
+
+	return rtc_valid_tm(tm);
+}
+
+static int xlnx_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alrm)
+{
+	struct xlnx_rtc_dev *xrtcdev = dev_get_drvdata(dev);
+
+	rtc_time64_to_tm(readl(xrtcdev->reg_base + RTC_ALRM), &alrm->time);
+	alrm->enabled = readl(xrtcdev->reg_base + RTC_INT_MASK) & RTC_INT_ALRM;
+
+	return 0;
+}
+
+static int xlnx_rtc_alarm_irq_enable(struct device *dev, u32 enabled)
+{
+	struct xlnx_rtc_dev *xrtcdev = dev_get_drvdata(dev);
+
+	if (enabled)
+		writel(RTC_INT_ALRM, xrtcdev->reg_base + RTC_INT_EN);
+	else
+		writel(RTC_INT_ALRM, xrtcdev->reg_base + RTC_INT_DIS);
+
+	return 0;
+}
+
+static int xlnx_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alrm)
+{
+	struct xlnx_rtc_dev *xrtcdev = dev_get_drvdata(dev);
+	unsigned long alarm_time;
+
+	alarm_time = rtc_tm_to_time64(&alrm->time);
+
+	if (alarm_time > RTC_SEC_MAX_VAL)
+		return -EINVAL;
+
+	writel((u32)alarm_time, (xrtcdev->reg_base + RTC_ALRM));
+
+	xlnx_rtc_alarm_irq_enable(dev, alrm->enabled);
+
+	return 0;
+}
+
+static void xlnx_init_rtc(struct xlnx_rtc_dev *xrtcdev, u32 calibval)
+{
+	/*
+	 * 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.
+	 */
+	calibval &= RTC_CALIB_MASK;
+	writel(calibval, (xrtcdev->reg_base + RTC_CALIB_WR));
+}
+
+static const struct rtc_class_ops xlnx_rtc_ops = {
+	.set_time	  = xlnx_rtc_set_time,
+	.read_time	  = xlnx_rtc_read_time,
+	.read_alarm	  = xlnx_rtc_read_alarm,
+	.set_alarm	  = xlnx_rtc_set_alarm,
+	.alarm_irq_enable = xlnx_rtc_alarm_irq_enable,
+};
+
+static irqreturn_t xlnx_rtc_interrupt(int irq, void *id)
+{
+	struct xlnx_rtc_dev *xrtcdev = (struct xlnx_rtc_dev *)id;
+	unsigned int status;
+
+	status = readl(xrtcdev->reg_base + RTC_INT_STS);
+	/* Check if interrupt asserted */
+	if (!(status & (RTC_INT_SEC | RTC_INT_ALRM)))
+		return IRQ_NONE;
+
+	/* Clear interrupt */
+	writel(status, xrtcdev->reg_base + RTC_INT_STS);
+
+	if (status & RTC_INT_SEC)
+		rtc_update_irq(xrtcdev->rtc, 1, RTC_IRQF | RTC_UF);
+	if (status & RTC_INT_ALRM)
+		rtc_update_irq(xrtcdev->rtc, 1, RTC_IRQF | RTC_AF);
+
+	return IRQ_HANDLED;
+}
+
+static int xlnx_rtc_probe(struct platform_device *pdev)
+{
+	struct xlnx_rtc_dev *xrtcdev;
+	struct resource *res;
+	int ret;
+	unsigned int calibvalue;
+
+	xrtcdev = devm_kzalloc(&pdev->dev, sizeof(*xrtcdev), GFP_KERNEL);
+	if (!xrtcdev)
+		return -ENOMEM;
+
+	platform_set_drvdata(pdev, xrtcdev);
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+
+	xrtcdev->reg_base = devm_ioremap_resource(&pdev->dev, res);
+	if (IS_ERR(xrtcdev->reg_base))
+		return PTR_ERR(xrtcdev->reg_base);
+
+	xrtcdev->alarm_irq = platform_get_irq_byname(pdev, "alarm");
+	if (xrtcdev->alarm_irq < 0) {
+		dev_err(&pdev->dev, "no irq resource\n");
+		return xrtcdev->alarm_irq;
+	}
+	ret = devm_request_irq(&pdev->dev, xrtcdev->alarm_irq,
+			       xlnx_rtc_interrupt, 0,
+			       dev_name(&pdev->dev), xrtcdev);
+	if (ret) {
+		dev_err(&pdev->dev, "request irq failed\n");
+		return ret;
+	}
+
+	xrtcdev->sec_irq = platform_get_irq_byname(pdev, "sec");
+	if (xrtcdev->sec_irq < 0) {
+		dev_err(&pdev->dev, "no irq resource\n");
+		return xrtcdev->sec_irq;
+	}
+	ret = devm_request_irq(&pdev->dev, xrtcdev->sec_irq,
+			       xlnx_rtc_interrupt, 0,
+			       dev_name(&pdev->dev), xrtcdev);
+	if (ret) {
+		dev_err(&pdev->dev, "request irq failed\n");
+		return ret;
+	}
+
+	ret = of_property_read_u32(pdev->dev.of_node, "calibration",
+				   &calibvalue);
+	if (ret)
+		calibvalue = RTC_CALIB_DEF;
+
+	xlnx_init_rtc(xrtcdev, calibvalue);
+
+	device_init_wakeup(&pdev->dev, 1);
+
+	xrtcdev->rtc = devm_rtc_device_register(&pdev->dev, pdev->name,
+					 &xlnx_rtc_ops, THIS_MODULE);
+	return PTR_ERR_OR_ZERO(xrtcdev->rtc);
+}
+
+static int xlnx_rtc_remove(struct platform_device *pdev)
+{
+	xlnx_rtc_alarm_irq_enable(&pdev->dev, 0);
+	device_init_wakeup(&pdev->dev, 0);
+
+	return 0;
+}
+
+static int __maybe_unused xlnx_rtc_suspend(struct device *dev)
+{
+	struct platform_device *pdev = to_platform_device(dev);
+	struct xlnx_rtc_dev *xrtcdev = platform_get_drvdata(pdev);
+
+	if (device_may_wakeup(&pdev->dev))
+		enable_irq_wake(xrtcdev->alarm_irq);
+	else
+		xlnx_rtc_alarm_irq_enable(dev, 0);
+
+	return 0;
+}
+
+static int __maybe_unused xlnx_rtc_resume(struct device *dev)
+{
+	struct platform_device *pdev = to_platform_device(dev);
+	struct xlnx_rtc_dev *xrtcdev = platform_get_drvdata(pdev);
+
+	if (device_may_wakeup(&pdev->dev))
+		disable_irq_wake(xrtcdev->alarm_irq);
+	else
+		xlnx_rtc_alarm_irq_enable(dev, 1);
+
+	return 0;
+}
+
+static SIMPLE_DEV_PM_OPS(xlnx_rtc_pm_ops, xlnx_rtc_suspend, xlnx_rtc_resume);
+
+static const struct of_device_id xlnx_rtc_of_match[] = {
+	{.compatible = "xlnx,zynqmp-rtc" },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, xlnx_rtc_of_match);
+
+static struct platform_driver xlnx_rtc_driver = {
+	.probe		= xlnx_rtc_probe,
+	.remove		= xlnx_rtc_remove,
+	.driver		= {
+		.name	= KBUILD_MODNAME,
+		.pm	= &xlnx_rtc_pm_ops,
+		.of_match_table	= xlnx_rtc_of_match,
+	},
+};
+
+module_platform_driver(xlnx_rtc_driver);
+
+MODULE_DESCRIPTION("Xilinx Zynq MPSoC RTC driver");
+MODULE_AUTHOR("Xilinx Inc.");
+MODULE_LICENSE("GPL v2");