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authorJonathan Neuschäfer <j.neuschaefer@gmx.net>2021-01-24 22:41:25 +0100
committerLee Jones <lee.jones@linaro.org>2021-03-10 11:06:33 +0000
commit435af89786c674583b188f7322fee5c03894b8b7 (patch)
tree887091a988cb13068b98652b9d3aa866bbc6de5a
parent9fc0486f948f00f90cba4da9e3b2b58ff00b2a53 (diff)
rtc: New driver for RTC in Netronix embedded controller
With this driver, mainline Linux can keep its time and date in sync with the vendor kernel. Advanced functionality like alarm and automatic power-on is not yet supported. Signed-off-by: Jonathan Neuschäfer <j.neuschaefer@gmx.net> Acked-by: Alexandre Belloni <alexandre.belloni@bootlin.com> Signed-off-by: Lee Jones <lee.jones@linaro.org>
-rw-r--r--drivers/rtc/Kconfig8
-rw-r--r--drivers/rtc/Makefile1
-rw-r--r--drivers/rtc/rtc-ntxec.c145
3 files changed, 154 insertions, 0 deletions
diff --git a/drivers/rtc/Kconfig b/drivers/rtc/Kconfig
index ce723dc54aa4..e6205f7a7d59 100644
--- a/drivers/rtc/Kconfig
+++ b/drivers/rtc/Kconfig
@@ -1296,6 +1296,14 @@ config RTC_DRV_CROS_EC
This driver can also be built as a module. If so, the module
will be called rtc-cros-ec.
+config RTC_DRV_NTXEC
+ tristate "Netronix embedded controller RTC"
+ depends on MFD_NTXEC
+ help
+ Say yes here if you want to support the RTC functionality of the
+ embedded controller found in certain e-book readers designed by the
+ original design manufacturer Netronix.
+
comment "on-CPU RTC drivers"
config RTC_DRV_ASM9260
diff --git a/drivers/rtc/Makefile b/drivers/rtc/Makefile
index 4e930183c170..2dd0dd956b0e 100644
--- a/drivers/rtc/Makefile
+++ b/drivers/rtc/Makefile
@@ -108,6 +108,7 @@ obj-$(CONFIG_RTC_DRV_MT7622) += rtc-mt7622.o
obj-$(CONFIG_RTC_DRV_MV) += rtc-mv.o
obj-$(CONFIG_RTC_DRV_MXC) += rtc-mxc.o
obj-$(CONFIG_RTC_DRV_MXC_V2) += rtc-mxc_v2.o
+obj-$(CONFIG_RTC_DRV_NTXEC) += rtc-ntxec.o
obj-$(CONFIG_RTC_DRV_OMAP) += rtc-omap.o
obj-$(CONFIG_RTC_DRV_OPAL) += rtc-opal.o
obj-$(CONFIG_RTC_DRV_PALMAS) += rtc-palmas.o
diff --git a/drivers/rtc/rtc-ntxec.c b/drivers/rtc/rtc-ntxec.c
new file mode 100644
index 000000000000..850ca49186fd
--- /dev/null
+++ b/drivers/rtc/rtc-ntxec.c
@@ -0,0 +1,145 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * The Netronix embedded controller is a microcontroller found in some
+ * e-book readers designed by the original design manufacturer Netronix, Inc.
+ * It contains RTC, battery monitoring, system power management, and PWM
+ * functionality.
+ *
+ * This driver implements access to the RTC time and date.
+ *
+ * Copyright 2020 Jonathan Neuschäfer <j.neuschaefer@gmx.net>
+ */
+
+#include <linux/mfd/ntxec.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/regmap.h>
+#include <linux/rtc.h>
+#include <linux/types.h>
+
+struct ntxec_rtc {
+ struct device *dev;
+ struct ntxec *ec;
+};
+
+#define NTXEC_REG_WRITE_YEAR 0x10
+#define NTXEC_REG_WRITE_MONTH 0x11
+#define NTXEC_REG_WRITE_DAY 0x12
+#define NTXEC_REG_WRITE_HOUR 0x13
+#define NTXEC_REG_WRITE_MINUTE 0x14
+#define NTXEC_REG_WRITE_SECOND 0x15
+
+#define NTXEC_REG_READ_YEAR_MONTH 0x20
+#define NTXEC_REG_READ_MDAY_HOUR 0x21
+#define NTXEC_REG_READ_MINUTE_SECOND 0x23
+
+static int ntxec_read_time(struct device *dev, struct rtc_time *tm)
+{
+ struct ntxec_rtc *rtc = dev_get_drvdata(dev);
+ unsigned int value;
+ int res;
+
+retry:
+ res = regmap_read(rtc->ec->regmap, NTXEC_REG_READ_MINUTE_SECOND, &value);
+ if (res < 0)
+ return res;
+
+ tm->tm_min = value >> 8;
+ tm->tm_sec = value & 0xff;
+
+ res = regmap_read(rtc->ec->regmap, NTXEC_REG_READ_MDAY_HOUR, &value);
+ if (res < 0)
+ return res;
+
+ tm->tm_mday = value >> 8;
+ tm->tm_hour = value & 0xff;
+
+ res = regmap_read(rtc->ec->regmap, NTXEC_REG_READ_YEAR_MONTH, &value);
+ if (res < 0)
+ return res;
+
+ tm->tm_year = (value >> 8) + 100;
+ tm->tm_mon = (value & 0xff) - 1;
+
+ /*
+ * Read the minutes/seconds field again. If it changed since the first
+ * read, we can't assume that the values read so far are consistent,
+ * and should start from the beginning.
+ */
+ res = regmap_read(rtc->ec->regmap, NTXEC_REG_READ_MINUTE_SECOND, &value);
+ if (res < 0)
+ return res;
+
+ if (tm->tm_min != value >> 8 || tm->tm_sec != (value & 0xff))
+ goto retry;
+
+ return 0;
+}
+
+static int ntxec_set_time(struct device *dev, struct rtc_time *tm)
+{
+ struct ntxec_rtc *rtc = dev_get_drvdata(dev);
+
+ /*
+ * To avoid time overflows while we're writing the full date/time,
+ * set the seconds field to zero before doing anything else. For the
+ * next 59 seconds (plus however long it takes until the RTC's next
+ * update of the second field), the seconds field will not overflow
+ * into the other fields.
+ */
+ struct reg_sequence regs[] = {
+ { NTXEC_REG_WRITE_SECOND, ntxec_reg8(0) },
+ { NTXEC_REG_WRITE_YEAR, ntxec_reg8(tm->tm_year - 100) },
+ { NTXEC_REG_WRITE_MONTH, ntxec_reg8(tm->tm_mon + 1) },
+ { NTXEC_REG_WRITE_DAY, ntxec_reg8(tm->tm_mday) },
+ { NTXEC_REG_WRITE_HOUR, ntxec_reg8(tm->tm_hour) },
+ { NTXEC_REG_WRITE_MINUTE, ntxec_reg8(tm->tm_min) },
+ { NTXEC_REG_WRITE_SECOND, ntxec_reg8(tm->tm_sec) },
+ };
+
+ return regmap_multi_reg_write(rtc->ec->regmap, regs, ARRAY_SIZE(regs));
+}
+
+static const struct rtc_class_ops ntxec_rtc_ops = {
+ .read_time = ntxec_read_time,
+ .set_time = ntxec_set_time,
+};
+
+static int ntxec_rtc_probe(struct platform_device *pdev)
+{
+ struct rtc_device *dev;
+ struct ntxec_rtc *rtc;
+
+ pdev->dev.of_node = pdev->dev.parent->of_node;
+
+ rtc = devm_kzalloc(&pdev->dev, sizeof(*rtc), GFP_KERNEL);
+ if (!rtc)
+ return -ENOMEM;
+
+ rtc->dev = &pdev->dev;
+ rtc->ec = dev_get_drvdata(pdev->dev.parent);
+ platform_set_drvdata(pdev, rtc);
+
+ dev = devm_rtc_allocate_device(&pdev->dev);
+ if (IS_ERR(dev))
+ return PTR_ERR(dev);
+
+ dev->ops = &ntxec_rtc_ops;
+ dev->range_min = RTC_TIMESTAMP_BEGIN_2000;
+ dev->range_max = 9025257599LL; /* 2255-12-31 23:59:59 */
+
+ return devm_rtc_register_device(dev);
+}
+
+static struct platform_driver ntxec_rtc_driver = {
+ .driver = {
+ .name = "ntxec-rtc",
+ },
+ .probe = ntxec_rtc_probe,
+};
+module_platform_driver(ntxec_rtc_driver);
+
+MODULE_AUTHOR("Jonathan Neuschäfer <j.neuschaefer@gmx.net>");
+MODULE_DESCRIPTION("RTC driver for Netronix EC");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS("platform:ntxec-rtc");