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 <[email protected]>
---
v4:
- Remove "driver" from Kconfig entry for consistency with most other entries
- Add missing MODULE_ALIAS line
- Give NTXEC_REG_READ_ macros longer names
- Solve the read tearing issue using Alexandre Belloni's algorithm
- Solve the write tearing issue using Uwe Kleine-König's algorithm
- Spell out ODM
v3:
- https://lore.kernel.org/lkml/[email protected]/
- Add email address to copyright line
- Remove OF compatible string and don't include linux/of_device.h
- Don't use a comma after sentinels
- Avoid ret |= ... pattern
- Move 8-bit register conversion to ntxec.h
- Relicense as GPLv2 or later
v2:
- https://lore.kernel.org/lkml/[email protected]/
- 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 | 158 ++++++++++++++++++++++++++++++++++++++++
3 files changed, 167 insertions(+)
create mode 100644 drivers/rtc/rtc-ntxec.c
diff --git a/drivers/rtc/Kconfig b/drivers/rtc/Kconfig
index 65ad9d0b47ab1..fe009949728b3 100644
--- a/drivers/rtc/Kconfig
+++ b/drivers/rtc/Kconfig
@@ -1311,6 +1311,14 @@ 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 bfb57464118d0..5f2a7582b2780 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..dad5aba2852f1
--- /dev/null
+++ b/drivers/rtc/rtc-ntxec.c
@@ -0,0 +1,158 @@
+// 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 <[email protected]>
+ */
+
+#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);
+ int res = 0;
+
+ /*
+ * 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.
+ */
+ res = regmap_write(rtc->ec->regmap, NTXEC_REG_WRITE_SECOND, ntxec_reg8(0));
+ if (res)
+ return res;
+
+ res = regmap_write(rtc->ec->regmap, NTXEC_REG_WRITE_YEAR, ntxec_reg8(tm->tm_year - 100));
+ if (res)
+ return res;
+
+ res = regmap_write(rtc->ec->regmap, NTXEC_REG_WRITE_MONTH, ntxec_reg8(tm->tm_mon + 1));
+ if (res)
+ return res;
+
+ res = regmap_write(rtc->ec->regmap, NTXEC_REG_WRITE_DAY, ntxec_reg8(tm->tm_mday));
+ if (res)
+ return res;
+
+ res = regmap_write(rtc->ec->regmap, NTXEC_REG_WRITE_HOUR, ntxec_reg8(tm->tm_hour));
+ if (res)
+ return res;
+
+ res = regmap_write(rtc->ec->regmap, NTXEC_REG_WRITE_MINUTE, ntxec_reg8(tm->tm_min));
+ if (res)
+ return res;
+
+ return regmap_write(rtc->ec->regmap, NTXEC_REG_WRITE_SECOND, ntxec_reg8(tm->tm_sec));
+}
+
+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 = 9025257599LL; /* 2255-12-31 23:59:59 */
+
+ return 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 <[email protected]>");
+MODULE_DESCRIPTION("RTC driver for Netronix EC");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS("platform:ntxec-rtc");
--
2.29.2
Hi,
On 22/11/2020 23:27:37+0100, Jonathan Neusch?fer wrote:
> 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 Neusch?fer <[email protected]>
Acked-by: Alexandre Belloni <[email protected]>
However, two comments below:
> +static int ntxec_set_time(struct device *dev, struct rtc_time *tm)
> +{
> + struct ntxec_rtc *rtc = dev_get_drvdata(dev);
> + int res = 0;
> +
> + /*
> + * 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.
> + */
> + res = regmap_write(rtc->ec->regmap, NTXEC_REG_WRITE_SECOND, ntxec_reg8(0));
> + if (res)
> + return res;
> +
> + res = regmap_write(rtc->ec->regmap, NTXEC_REG_WRITE_YEAR, ntxec_reg8(tm->tm_year - 100));
> + if (res)
> + return res;
> +
> + res = regmap_write(rtc->ec->regmap, NTXEC_REG_WRITE_MONTH, ntxec_reg8(tm->tm_mon + 1));
> + if (res)
> + return res;
> +
> + res = regmap_write(rtc->ec->regmap, NTXEC_REG_WRITE_DAY, ntxec_reg8(tm->tm_mday));
> + if (res)
> + return res;
> +
> + res = regmap_write(rtc->ec->regmap, NTXEC_REG_WRITE_HOUR, ntxec_reg8(tm->tm_hour));
> + if (res)
> + return res;
> +
> + res = regmap_write(rtc->ec->regmap, NTXEC_REG_WRITE_MINUTE, ntxec_reg8(tm->tm_min));
> + if (res)
> + return res;
> +
> + return regmap_write(rtc->ec->regmap, NTXEC_REG_WRITE_SECOND, ntxec_reg8(tm->tm_sec));
Couldn't you do a regmap_block_write or a regmap_multi_reg_write which
would be more efficient as they would be locking the regmap only once.
> +}
> +
> +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 = 9025257599LL; /* 2255-12-31 23:59:59 */
> +
> + return rtc_register_device(dev);
Note that this won't compile after
https://git.kernel.org/pub/scm/linux/kernel/git/abelloni/linux.git/commit/?id=fdcfd854333be5b30377dc5daa9cd0fa1643a979
We can solve that with immutable branches though.
--
Alexandre Belloni, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com
On Mon, Nov 23, 2020 at 12:10:54AM +0100, Alexandre Belloni wrote:
> Hi,
>
> On 22/11/2020 23:27:37+0100, Jonathan Neuschäfer wrote:
> > 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 <[email protected]>
> Acked-by: Alexandre Belloni <[email protected]>
>
> However, two comments below:
>
> > +static int ntxec_set_time(struct device *dev, struct rtc_time *tm)
> > +{
> > + struct ntxec_rtc *rtc = dev_get_drvdata(dev);
> > + int res = 0;
> > +
> > + /*
> > + * 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.
> > + */
> > + res = regmap_write(rtc->ec->regmap, NTXEC_REG_WRITE_SECOND, ntxec_reg8(0));
> > + if (res)
> > + return res;
> > +
> > + res = regmap_write(rtc->ec->regmap, NTXEC_REG_WRITE_YEAR, ntxec_reg8(tm->tm_year - 100));
> > + if (res)
> > + return res;
> > +
> > + res = regmap_write(rtc->ec->regmap, NTXEC_REG_WRITE_MONTH, ntxec_reg8(tm->tm_mon + 1));
> > + if (res)
> > + return res;
> > +
> > + res = regmap_write(rtc->ec->regmap, NTXEC_REG_WRITE_DAY, ntxec_reg8(tm->tm_mday));
> > + if (res)
> > + return res;
> > +
> > + res = regmap_write(rtc->ec->regmap, NTXEC_REG_WRITE_HOUR, ntxec_reg8(tm->tm_hour));
> > + if (res)
> > + return res;
> > +
> > + res = regmap_write(rtc->ec->regmap, NTXEC_REG_WRITE_MINUTE, ntxec_reg8(tm->tm_min));
> > + if (res)
> > + return res;
> > +
> > + return regmap_write(rtc->ec->regmap, NTXEC_REG_WRITE_SECOND, ntxec_reg8(tm->tm_sec));
>
> Couldn't you do a regmap_block_write or a regmap_multi_reg_write which
> would be more efficient as they would be locking the regmap only once.
I can't find regmap_block_write anywhere, but regmap_multi_reg_write
looks like a good approach to simplify the code here.
[...]
> Note that this won't compile after
> https://git.kernel.org/pub/scm/linux/kernel/git/abelloni/linux.git/commit/?id=fdcfd854333be5b30377dc5daa9cd0fa1643a979
>
> We can solve that with immutable branches though.
Thanks for the heads-up. Please let me know if/when there is any action
that I need to take here.
Jonathan
On Mon, Nov 23, 2020 at 10:31:05PM +0100, Jonathan Neusch?fer wrote:
> On Mon, Nov 23, 2020 at 12:10:54AM +0100, Alexandre Belloni wrote:
> > Couldn't you do a regmap_block_write or a regmap_multi_reg_write which
> > would be more efficient as they would be locking the regmap only once.
> I can't find regmap_block_write anywhere, but regmap_multi_reg_write
> looks like a good approach to simplify the code here.
I suspect he's thinking of bulk rather than block there.
On 23/11/2020 22:31:05+0100, Jonathan Neusch?fer wrote:
> > > + res = regmap_write(rtc->ec->regmap, NTXEC_REG_WRITE_MINUTE, ntxec_reg8(tm->tm_min));
> > > + if (res)
> > > + return res;
> > > +
> > > + return regmap_write(rtc->ec->regmap, NTXEC_REG_WRITE_SECOND, ntxec_reg8(tm->tm_sec));
> >
> > Couldn't you do a regmap_block_write or a regmap_multi_reg_write which
> > would be more efficient as they would be locking the regmap only once.
>
> I can't find regmap_block_write anywhere, but regmap_multi_reg_write
> looks like a good approach to simplify the code here.
>
I was thinking regmap_bulk_write but regmap_multi_reg_write is probably
more fitting here.
>
> [...]
> > Note that this won't compile after
> > https://git.kernel.org/pub/scm/linux/kernel/git/abelloni/linux.git/commit/?id=fdcfd854333be5b30377dc5daa9cd0fa1643a979
> >
> > We can solve that with immutable branches though.
>
> Thanks for the heads-up. Please let me know if/when there is any action
> that I need to take here.
>
I wouldn't think so, I can carry a patch once Lee provides his usual
immutable branch.
--
Alexandre Belloni, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com