rtc: Add ASPEED RTC driver
Read and writes the time to the non-battery backed RTC in the ASPEED BMC
system on chip families.
Signed-off-by: Joel Stanley <joel@jms.id.au>
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
diff --git a/drivers/rtc/rtc-aspeed.c b/drivers/rtc/rtc-aspeed.c
new file mode 100644
index 0000000..af3eb67
--- /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");