1 files changed, 177 insertions, 0 deletions

diff --git a/drivers/rtc/rtc-wilco-ec.c b/drivers/rtc/rtc-wilco-ec.c
new file mode 100644
index 000000000000..e62bda0cb53e
--- /dev/null
+++ b/drivers/rtc/rtc-wilco-ec.c
@@ -0,0 +1,177 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * RTC interface for Wilco Embedded Controller with R/W abilities
+ *
+ * Copyright 2018 Google LLC
+ *
+ * The corresponding platform device is typically registered in
+ * drivers/platform/chrome/wilco_ec/core.c
+ */
+
+#include <linux/bcd.h>
+#include <linux/err.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/platform_data/wilco-ec.h>
+#include <linux/rtc.h>
+#include <linux/timekeeping.h>
+
+#define EC_COMMAND_CMOS                 0x7c
+#define EC_CMOS_TOD_WRITE               0x02
+#define EC_CMOS_TOD_READ                0x08
+
+/**
+ * struct ec_rtc_read - Format of RTC returned by EC.
+ * @second: Second value (0..59)
+ * @minute: Minute value (0..59)
+ * @hour: Hour value (0..23)
+ * @day: Day value (1..31)
+ * @month: Month value (1..12)
+ * @year: Year value (full year % 100)
+ * @century: Century value (full year / 100)
+ *
+ * All values are presented in binary (not BCD).
+ */
+struct ec_rtc_read {
+        u8 second;
+        u8 minute;
+        u8 hour;
+        u8 day;
+        u8 month;
+        u8 year;
+        u8 century;
+} __packed;
+
+/**
+ * struct ec_rtc_write - Format of RTC sent to the EC.
+ * @param: EC_CMOS_TOD_WRITE
+ * @century: Century value (full year / 100)
+ * @year: Year value (full year % 100)
+ * @month: Month value (1..12)
+ * @day: Day value (1..31)
+ * @hour: Hour value (0..23)
+ * @minute: Minute value (0..59)
+ * @second: Second value (0..59)
+ * @weekday: Day of the week (0=Saturday)
+ *
+ * All values are presented in BCD.
+ */
+struct ec_rtc_write {
+        u8 param;
+        u8 century;
+        u8 year;
+        u8 month;
+        u8 day;
+        u8 hour;
+        u8 minute;
+        u8 second;
+        u8 weekday;
+} __packed;
+
+static int wilco_ec_rtc_read(struct device *dev, struct rtc_time *tm)
+{
+        struct wilco_ec_device *ec = dev_get_drvdata(dev->parent);
+        u8 param = EC_CMOS_TOD_READ;
+        struct ec_rtc_read rtc;
+        struct wilco_ec_message msg = {
+                .type = WILCO_EC_MSG_LEGACY,
+                .flags = WILCO_EC_FLAG_RAW_RESPONSE,
+                .command = EC_COMMAND_CMOS,
+                .request_data = &param,
+                .request_size = sizeof(param),
+                .response_data = &rtc,
+                .response_size = sizeof(rtc),
+        };
+        int ret;
+
+        ret = wilco_ec_mailbox(ec, &msg);
+        if (ret < 0)
+                return ret;
+
+        tm->tm_sec      = rtc.second;
+        tm->tm_min      = rtc.minute;
+        tm->tm_hour     = rtc.hour;
+        tm->tm_mday     = rtc.day;
+        tm->tm_mon      = rtc.month - 1;
+        tm->tm_year     = rtc.year + (rtc.century * 100) - 1900;
+        tm->tm_yday     = rtc_year_days(tm->tm_mday, tm->tm_mon, tm->tm_year);
+
+        /* Don't compute day of week, we don't need it. */
+        tm->tm_wday = -1;
+
+        return 0;
+}
+
+static int wilco_ec_rtc_write(struct device *dev, struct rtc_time *tm)
+{
+        struct wilco_ec_device *ec = dev_get_drvdata(dev->parent);
+        struct ec_rtc_write rtc;
+        struct wilco_ec_message msg = {
+                .type = WILCO_EC_MSG_LEGACY,
+                .flags = WILCO_EC_FLAG_RAW_RESPONSE,
+                .command = EC_COMMAND_CMOS,
+                .request_data = &rtc,
+                .request_size = sizeof(rtc),
+        };
+        int year = tm->tm_year + 1900;
+        /*
+         * Convert from 0=Sunday to 0=Saturday for the EC
+         * We DO need to set weekday because the EC controls battery charging
+         * schedules that depend on the day of the week.
+         */
+        int wday = tm->tm_wday == 6 ? 0 : tm->tm_wday + 1;
+        int ret;
+
+        rtc.param       = EC_CMOS_TOD_WRITE;
+        rtc.century     = bin2bcd(year / 100);
+        rtc.year        = bin2bcd(year % 100);
+        rtc.month       = bin2bcd(tm->tm_mon + 1);
+        rtc.day         = bin2bcd(tm->tm_mday);
+        rtc.hour        = bin2bcd(tm->tm_hour);
+        rtc.minute      = bin2bcd(tm->tm_min);
+        rtc.second      = bin2bcd(tm->tm_sec);
+        rtc.weekday     = bin2bcd(wday);
+
+        ret = wilco_ec_mailbox(ec, &msg);
+        if (ret < 0)
+                return ret;
+
+        return 0;
+}
+
+static const struct rtc_class_ops wilco_ec_rtc_ops = {
+        .read_time = wilco_ec_rtc_read,
+        .set_time = wilco_ec_rtc_write,
+};
+
+static int wilco_ec_rtc_probe(struct platform_device *pdev)
+{
+        struct rtc_device *rtc;
+
+        rtc = devm_rtc_allocate_device(&pdev->dev);
+        if (IS_ERR(rtc))
+                return PTR_ERR(rtc);
+
+        rtc->ops = &wilco_ec_rtc_ops;
+        /* EC only supports this century */
+        rtc->range_min = RTC_TIMESTAMP_BEGIN_2000;
+        rtc->range_max = RTC_TIMESTAMP_END_2099;
+        rtc->owner = THIS_MODULE;
+
+        return rtc_register_device(rtc);
+}
+
+static struct platform_driver wilco_ec_rtc_driver = {
+        .driver = {
+                .name = "rtc-wilco-ec",
+        },
+        .probe = wilco_ec_rtc_probe,
+};
+
+module_platform_driver(wilco_ec_rtc_driver);
+
+MODULE_ALIAS("platform:rtc-wilco-ec");
+MODULE_AUTHOR("Nick Crews <ncrews@chromium.org>");
+MODULE_LICENSE("GPL v2");
+MODULE_DESCRIPTION("Wilco EC RTC driver");