[PATCH v2 08/10] rtc: New driver for RTC in Netronix embedded controller

Jonathan Neuschäfer
2020-09-05T14:47:01Z

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>
---

v2:
- Rework top-of-file comment [Lee Jones]
- Sort the #include lines [Alexandre Belloni]
- don't align = signs in struct initializers [Uwe Kleine-König]
- Switch to regmap
- Fix register number used to read minutes and seconds
- Prefix registers with NTXEC_REG_
- Add help text to the Kconfig option
- Use devm_rtc_allocate_device and rtc_register_device, set ->range_min and ->range_max
---
drivers/rtc/Kconfig | 8 +++
drivers/rtc/Makefile | 1 +
drivers/rtc/rtc-ntxec.c | 130 ++++++++++++++++++++++++++++++++++++++++
3 files changed, 139 insertions(+)
create mode 100644 drivers/rtc/rtc-ntxec.c

diff --git a/drivers/rtc/Kconfig b/drivers/rtc/Kconfig
index 48c536acd777f..ae8f3dc36c9a3 100644
--- a/drivers/rtc/Kconfig
+++ b/drivers/rtc/Kconfig
@@ -1301,6 +1301,14 @@ 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 driver"
+ 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
+ ODM Netronix.
+
comment "on-CPU RTC drivers"

config RTC_DRV_ASM9260
diff --git a/drivers/rtc/Makefile b/drivers/rtc/Makefile
index 880e08a409c3d..733479db18896 100644
--- a/drivers/rtc/Makefile
+++ b/drivers/rtc/Makefile
@@ -111,6 +111,7 @@ 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 0000000000000..82eb6352353cd
--- /dev/null
+++ b/drivers/rtc/rtc-ntxec.c
@@ -0,0 +1,130 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * The Netronix embedded controller is a microcontroller found in some
+ * e-book readers designed by the ODM 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
+ */
+
+#include <linux/mfd/ntxec.h>
+#include <linux/module.h>
+#include <linux/of_device.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
+
+/* Convert an 8-bit value into the correct format for writing into a register */
+#define u8_to_reg(x) (((x) & 0xff) << 8)
+
+#define NTXEC_REG_READ_YM 0x20
+#define NTXEC_REG_READ_DH 0x21
+#define NTXEC_REG_READ_MS 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;
+
+ res = regmap_read(rtc->ec->regmap, NTXEC_REG_READ_YM, &value);
+ if (res < 0)
+ return res;
+
+ tm->tm_year = (value >> 8) + 100;
+ tm->tm_mon = (value & 0xff) - 1;
+
+ res = regmap_read(rtc->ec->regmap, NTXEC_REG_READ_DH, &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_MS, &value);
+ if (res < 0)
+ return res;
+
+ tm->tm_min = value >> 8;
+ tm->tm_sec = value & 0xff;
+
+ return 0;
+}
+
+static int ntxec_set_time(struct device *dev, struct rtc_time *tm)
+{
+ struct ntxec_rtc *rtc = dev_get_drvdata(dev);
+ int res = 0;
+
+ res |= regmap_write(rtc->ec->regmap, NTXEC_REG_WRITE_YEAR, u8_to_reg(tm->tm_year - 100));
+ res |= regmap_write(rtc->ec->regmap, NTXEC_REG_WRITE_MONTH, u8_to_reg(tm->tm_mon + 1));
+ res |= regmap_write(rtc->ec->regmap, NTXEC_REG_WRITE_DAY, u8_to_reg(tm->tm_mday));
+ res |= regmap_write(rtc->ec->regmap, NTXEC_REG_WRITE_HOUR, u8_to_reg(tm->tm_hour));
+ res |= regmap_write(rtc->ec->regmap, NTXEC_REG_WRITE_MINUTE, u8_to_reg(tm->tm_min));
+ res |= regmap_write(rtc->ec->regmap, NTXEC_REG_WRITE_SECOND, u8_to_reg(tm->tm_sec));
+
+ return (res < 0) ? -EIO : 0;
+}
+
+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;
+
+ 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 = RTC_TIMESTAMP_END_2255;
+
+ return rtc_register_device(dev);
+}
+
+static const struct of_device_id ntxec_rtc_of_match[] = {
+ { .compatible = "netronix,ntxec-rtc" },
+ { },
+};
+MODULE_DEVICE_TABLE(of, ntxec_rtc_of_match);
+
+static struct platform_driver ntxec_rtc_driver = {
+ .driver = {
+ .name = "ntxec-rtc",
+ .of_match_table = ntxec_rtc_of_match,
+ },
+ .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");
--
2.28.0