3 files changed, 148 insertions, 0 deletions

diff --git a/drivers/rtc/Kconfig b/drivers/rtc/Kconfig
index dc0d66e80038..fd1321875cb1 100644
--- a/drivers/rtc/Kconfig
+++ b/drivers/rtc/Kconfig
@@ -1841,6 +1841,17 @@ config RTC_DRV_RTD119X
           If you say yes here, you get support for the RTD1295 SoC
           Real Time Clock.
 
+config RTC_DRV_ASPEED
+        tristate "ASPEED RTC"
+        depends on OF
+        depends on ARCH_ASPEED || COMPILE_TEST
+        help
+          If you say yes here you get support for the ASPEED BMC SoC real time
+          clocks.
+
+          This driver can also be built as a module, if so, the module
+          will be called "rtc-aspeed".
+
 comment "HID Sensor RTC drivers"
 
 config RTC_DRV_HID_SENSOR_TIME
diff --git a/drivers/rtc/Makefile b/drivers/rtc/Makefile
index fe3962496685..9d997faa2c26 100644
--- a/drivers/rtc/Makefile
+++ b/drivers/rtc/Makefile
@@ -34,6 +34,7 @@ obj-$(CONFIG_RTC_DRV_AC100)	+= rtc-ac100.o
 obj-$(CONFIG_RTC_DRV_ARMADA38X) += rtc-armada38x.o
 obj-$(CONFIG_RTC_DRV_AS3722)    += rtc-as3722.o
 obj-$(CONFIG_RTC_DRV_ASM9260)   += rtc-asm9260.o
+obj-$(CONFIG_RTC_DRV_ASPEED)    += rtc-aspeed.o
 obj-$(CONFIG_RTC_DRV_AT91RM9200)+= rtc-at91rm9200.o
 obj-$(CONFIG_RTC_DRV_AT91SAM9)  += rtc-at91sam9.o
 obj-$(CONFIG_RTC_DRV_AU1XXX)    += rtc-au1xxx.o
diff --git a/drivers/rtc/rtc-aspeed.c b/drivers/rtc/rtc-aspeed.c
new file mode 100644
index 000000000000..af3eb676d7c3
--- /dev/null
+++ b/drivers/rtc/rtc-aspeed.c
@@ -0,0 +1,136 @@
+// SPDX-License-Identifier: GPL-2.0+
+// Copyright 2015 IBM Corp.
+
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/rtc.h>
+#include <linux/io.h>
+
+struct aspeed_rtc {
+        struct rtc_device *rtc_dev;
+        void __iomem *base;
+};
+
+#define RTC_TIME        0x00
+#define RTC_YEAR        0x04
+#define RTC_CTRL        0x10
+
+#define RTC_UNLOCK      BIT(1)
+#define RTC_ENABLE      BIT(0)
+
+static int aspeed_rtc_read_time(struct device *dev, struct rtc_time *tm)
+{
+        struct aspeed_rtc *rtc = dev_get_drvdata(dev);
+        unsigned int cent, year;
+        u32 reg1, reg2;
+
+        if (!(readl(rtc->base + RTC_CTRL) & RTC_ENABLE)) {
+                dev_dbg(dev, "%s failing as rtc disabled\n", __func__);
+                return -EINVAL;
+        }
+
+        do {
+                reg2 = readl(rtc->base + RTC_YEAR);
+                reg1 = readl(rtc->base + RTC_TIME);
+        } while (reg2 != readl(rtc->base + RTC_YEAR));
+
+        tm->tm_mday = (reg1 >> 24) & 0x1f;
+        tm->tm_hour = (reg1 >> 16) & 0x1f;
+        tm->tm_min = (reg1 >> 8) & 0x3f;
+        tm->tm_sec = (reg1 >> 0) & 0x3f;
+
+        cent = (reg2 >> 16) & 0x1f;
+        year = (reg2 >> 8) & 0x7f;
+        tm->tm_mon = ((reg2 >>  0) & 0x0f) - 1;
+        tm->tm_year = year + (cent * 100) - 1900;
+
+        dev_dbg(dev, "%s %ptR", __func__, tm);
+
+        return 0;
+}
+
+static int aspeed_rtc_set_time(struct device *dev, struct rtc_time *tm)
+{
+        struct aspeed_rtc *rtc = dev_get_drvdata(dev);
+        u32 reg1, reg2, ctrl;
+        int year, cent;
+
+        cent = (tm->tm_year + 1900) / 100;
+        year = tm->tm_year % 100;
+
+        reg1 = (tm->tm_mday << 24) | (tm->tm_hour << 16) | (tm->tm_min << 8) |
+                tm->tm_sec;
+
+        reg2 = ((cent & 0x1f) << 16) | ((year & 0x7f) << 8) |
+                ((tm->tm_mon + 1) & 0xf);
+
+        ctrl = readl(rtc->base + RTC_CTRL);
+        writel(ctrl | RTC_UNLOCK, rtc->base + RTC_CTRL);
+
+        writel(reg1, rtc->base + RTC_TIME);
+        writel(reg2, rtc->base + RTC_YEAR);
+
+        /* Re-lock and ensure enable is set now that a time is programmed */
+        writel(ctrl | RTC_ENABLE, rtc->base + RTC_CTRL);
+
+        return 0;
+}
+
+static const struct rtc_class_ops aspeed_rtc_ops = {
+        .read_time = aspeed_rtc_read_time,
+        .set_time = aspeed_rtc_set_time,
+};
+
+static int aspeed_rtc_probe(struct platform_device *pdev)
+{
+        struct aspeed_rtc *rtc;
+        struct resource *res;
+        int ret;
+
+        rtc = devm_kzalloc(&pdev->dev, sizeof(*rtc), GFP_KERNEL);
+        if (!rtc)
+                return -ENOMEM;
+
+        res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+        rtc->base = devm_ioremap_resource(&pdev->dev, res);
+        if (IS_ERR(rtc->base))
+                return PTR_ERR(rtc->base);
+
+        rtc->rtc_dev = devm_rtc_allocate_device(&pdev->dev);
+        if (IS_ERR(rtc->rtc_dev))
+                return PTR_ERR(rtc->rtc_dev);
+
+        platform_set_drvdata(pdev, rtc);
+
+        rtc->rtc_dev->ops = &aspeed_rtc_ops;
+        rtc->rtc_dev->range_min = RTC_TIMESTAMP_BEGIN_1900;
+        rtc->rtc_dev->range_max = 38814989399LL; /* 3199-12-31 23:59:59 */
+
+        ret = rtc_register_device(rtc->rtc_dev);
+        if (ret)
+                return ret;
+
+        return 0;
+}
+
+static const struct of_device_id aspeed_rtc_match[] = {
+        { .compatible = "aspeed,ast2400-rtc", },
+        { .compatible = "aspeed,ast2500-rtc", },
+        { .compatible = "aspeed,ast2600-rtc", },
+        {}
+};
+MODULE_DEVICE_TABLE(of, aspeed_rtc_match);
+
+static struct platform_driver aspeed_rtc_driver = {
+        .driver = {
+                .name = "aspeed-rtc",
+                .of_match_table = of_match_ptr(aspeed_rtc_match),
+        },
+};
+
+module_platform_driver_probe(aspeed_rtc_driver, aspeed_rtc_probe);
+
+MODULE_DESCRIPTION("ASPEED RTC driver");
+MODULE_AUTHOR("Joel Stanley <joel@jms.id.au>");
+MODULE_LICENSE("GPL");