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/Kconfig b/drivers/rtc/Kconfig
index dc0d66e..fd13218 100644 (file)
--- 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 fe39624..9d997fa 100644 (file)
--- 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 (file)
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");