[PATCH v2 02/10] MIPS: ranchu: Add Goldfish RTC driver

[Aleksandar Markovic <aleksandar.markovic@rt-rk.com>]

From: Aleksandar Markovic <aleksandar.markovic@imgtec.com>

Add device driver for a virtual Goldfish RTC clock.

The driver can be built only if CONFIG_MIPS and CONFIG_GOLDFISH are
set. The compatible string used by OS for binding the driver is
defined as "google,goldfish-rtc".

Signed-off-by: Miodrag Dinic <miodrag.dinic@imgtec.com>
Signed-off-by: Goran Ferenc <goran.ferenc@imgtec.com>
Signed-off-by: Aleksandar Markovic <aleksandar.markovic@imgtec.com>
---
 MAINTAINERS                |   1 +
 drivers/rtc/Kconfig        |   6 ++
 drivers/rtc/Makefile       |   1 +
 drivers/rtc/rtc-goldfish.c | 136 +++++++++++++++++++++++++++++++++++++++++++++
 4 files changed, 144 insertions(+)
 create mode 100644 drivers/rtc/rtc-goldfish.c

diff --git a/MAINTAINERS b/MAINTAINERS
index 519cdef..26a1267 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -845,6 +845,7 @@ ANDROID GOLDFISH RTC DRIVER
 M:	Miodrag Dinic <miodrag.dinic@imgtec.com>
 S:	Supported
 F:	Documentation/devicetree/bindings/rtc/google,goldfish-rtc.txt
+F:	drivers/rtc/rtc-goldfish.c
 
 ANDROID ION DRIVER
 M:	Laura Abbott <labbott@redhat.com>
diff --git a/drivers/rtc/Kconfig b/drivers/rtc/Kconfig
index 8d3b957..510c5b7 100644
--- a/drivers/rtc/Kconfig
+++ b/drivers/rtc/Kconfig
@@ -1753,5 +1753,11 @@ config RTC_DRV_HID_SENSOR_TIME
 	  If this driver is compiled as a module, it will be named
 	  rtc-hid-sensor-time.
 
+config RTC_DRV_GOLDFISH
+	tristate "Goldfish Real Time Clock"
+	depends on MIPS
+	depends on GOLDFISH
+	help
+	  Say yes here to build support for the Goldfish RTC.
 
 endif # RTC_CLASS
diff --git a/drivers/rtc/Makefile b/drivers/rtc/Makefile
index 13857d2..dfc38f5 100644
--- a/drivers/rtc/Makefile
+++ b/drivers/rtc/Makefile
@@ -168,3 +168,4 @@ 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
+obj-$(CONFIG_RTC_DRV_GOLDFISH)	+= rtc-goldfish.o
diff --git a/drivers/rtc/rtc-goldfish.c b/drivers/rtc/rtc-goldfish.c
new file mode 100644
index 0000000..e206a98
--- /dev/null
+++ b/drivers/rtc/rtc-goldfish.c
@@ -0,0 +1,136 @@
+/* drivers/rtc/rtc-goldfish.c
+ *
+ * Copyright (C) 2007 Google, Inc.
+ * Copyright (C) 2017 Imagination Technologies Ltd.
+ *
+ * This software is licensed under the terms of the GNU General Public
+ * License version 2, as published by the Free Software Foundation, and
+ * may be copied, distributed, and modified under those terms.
+ *
+ * This program is distributed in the hope that 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.
+ *
+ */
+
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/rtc.h>
+
+#define TIMER_TIME_LOW         0x00	/* get low bits of current time  */
+					/*   and update TIMER_TIME_HIGH  */
+#define TIMER_TIME_HIGH        0x04	/* get high bits of time at last */
+					/*   TIMER_TIME_LOW read         */
+#define TIMER_ALARM_LOW        0x08	/* set low bits of alarm and     */
+					/*   activate it                 */
+#define TIMER_ALARM_HIGH       0x0c	/* set high bits of next alarm   */
+#define TIMER_CLEAR_INTERRUPT  0x10
+#define TIMER_CLEAR_ALARM      0x14
+
+struct goldfish_rtc {
+	void __iomem *base;
+	u32 irq;
+	struct rtc_device *rtc;
+};
+
+static irqreturn_t goldfish_rtc_interrupt(int irq, void *dev_id)
+{
+	struct goldfish_rtc	*qrtc = dev_id;
+	unsigned long		events = 0;
+	void __iomem *base = qrtc->base;
+
+	writel(1, base + TIMER_CLEAR_INTERRUPT);
+	events = RTC_IRQF | RTC_AF;
+
+	rtc_update_irq(qrtc->rtc, 1, events);
+
+	return IRQ_HANDLED;
+}
+
+static int goldfish_rtc_read_time(struct device *dev, struct rtc_time *tm)
+{
+	u64 time;
+	u64 time_low;
+	u64 time_high;
+	u64 time_high_prev;
+
+	struct goldfish_rtc *qrtc =
+			platform_get_drvdata(to_platform_device(dev));
+	void __iomem *base = qrtc->base;
+
+	time_high = readl(base + TIMER_TIME_HIGH);
+	do {
+		time_high_prev = time_high;
+		time_low = readl(base + TIMER_TIME_LOW);
+		time_high = readl(base + TIMER_TIME_HIGH);
+	} while (time_high != time_high_prev);
+	time = (time_high << 32) | time_low;
+
+	do_div(time, NSEC_PER_SEC);
+
+	rtc_time_to_tm(time, tm);
+
+	return 0;
+}
+
+static const struct rtc_class_ops goldfish_rtc_ops = {
+	.read_time	= goldfish_rtc_read_time,
+};
+
+static int goldfish_rtc_probe(struct platform_device *pdev)
+{
+	struct resource *r;
+	struct goldfish_rtc *qrtc;
+	unsigned long rtc_dev_len;
+	unsigned long rtc_dev_addr;
+	int err;
+
+	qrtc = devm_kzalloc(&pdev->dev, sizeof(*qrtc), GFP_KERNEL);
+	if (qrtc == NULL)
+		return -ENOMEM;
+
+	platform_set_drvdata(pdev, qrtc);
+
+	r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	if (r == NULL)
+		return -ENODEV;
+
+	rtc_dev_addr = r->start;
+	rtc_dev_len = resource_size(r);
+	qrtc->base = devm_ioremap(&pdev->dev, rtc_dev_addr, rtc_dev_len);
+	if (IS_ERR(qrtc->base))
+		return -ENODEV;
+
+	qrtc->irq = platform_get_irq(pdev, 0);
+	if (qrtc->irq < 0)
+		return -ENODEV;
+
+	qrtc->rtc = devm_rtc_device_register(&pdev->dev, pdev->name,
+					&goldfish_rtc_ops, THIS_MODULE);
+	if (IS_ERR(qrtc->rtc))
+		return PTR_ERR(qrtc->rtc);
+
+	err = devm_request_irq(&pdev->dev, qrtc->irq, goldfish_rtc_interrupt,
+		0, pdev->name, qrtc);
+	if (err)
+		return err;
+
+	return 0;
+}
+
+static const struct of_device_id goldfish_rtc_of_match[] = {
+	{ .compatible = "google,goldfish-rtc", },
+	{},
+};
+MODULE_DEVICE_TABLE(of, goldfish_rtc_of_match);
+
+static struct platform_driver goldfish_rtc = {
+	.probe = goldfish_rtc_probe,
+	.driver = {
+		.name = "goldfish_rtc",
+		.of_match_table = goldfish_rtc_of_match,
+	}
+};
+
+module_platform_driver(goldfish_rtc);
-- 
2.7.4