[PATCH v5 0/2] Add support for the DFRobot SD2405AL I2C RTC Module.

[PATCH v5 0/2] Add support for the DFRobot SD2405AL I2C RTC Module.

[Tóth János via B4 Relay]

This patch series adds a driver and the documentation for the SD2405AL I2C RTC.

Signed-off-by: Tóth János <gomba007@gmail.com>
---
Changes in v5:
- Rework based on Alexandre Belloni's suggestions.
- Drop explicit initialization of struct i2c_device_id::driver_data.
- Add documentation.
- Link to v4: https://lore.kernel.org/r/20240624-rtc-sd2405al-v4-1-2b2bc759f98f@gmail.com

Changes in v4:
- Implement more comprehensive data validation.
- Inline some temporary variables.
- Link to v3: https://lore.kernel.org/r/20240620-rtc-sd2405al-v3-1-65d5bb01af50@gmail.com

Changes in v3:
- #define-s of registers are reworked.
- Minor revisions based on the reviewer's suggestions.
- Link to v2: https://lore.kernel.org/r/20240619-rtc-sd2405al-v2-1-39bea29bd2a5@gmail.com

Changes in v2:
- Refactored based on reviewer's suggestions.
- I couldn't get the I2C IRQ to work on Raspberry Pi 4, so alarm is
  skipped.
- Link to v1: https://lore.kernel.org/r/20240607-rtc-sd2405al-v1-1-535971e7a866@gmail.com

---
Tóth János (2):
      drivers: rtc: Add driver for SD2405AL.
      dt-bindings: rtc: Add support for SD2405AL.

 .../devicetree/bindings/rtc/trivial-rtc.yaml       |   2 +
 .../devicetree/bindings/vendor-prefixes.yaml       |   2 +
 MAINTAINERS                                        |   6 +
 drivers/rtc/Kconfig                                |  10 +
 drivers/rtc/Makefile                               |   1 +
 drivers/rtc/rtc-sd2405al.c                         | 227 +++++++++++++++++++++
 6 files changed, 248 insertions(+)
---
base-commit: c3f38fa61af77b49866b006939479069cd451173
change-id: 20240607-rtc-sd2405al-a0947377c73d

Best regards,
-- 
Tóth János <gomba007@gmail.com>

[PATCH v5 1/2] drivers: rtc: Add driver for SD2405AL.

[Tóth János via B4 Relay]

From: Tóth János <gomba007@gmail.com>

Add support for the DFRobot SD2405AL I2C RTC Module.

Datasheet:
	https://image.dfrobot.com/image/data/TOY0021/SD2405AL%20datasheet%20(Angelo%20v0.1).pdf

Product:
	https://www.dfrobot.com/product-1600.html

To instantiate (assuming device is connected to I2C-1)
as root:
	echo sd2405al 0x32 > /sys/bus/i2c/devices/i2c-1/new_device
as user:
	echo 'sd2405al 0x32' | sudo tee /sys/class/i2c-adapter/i2c-1/new_device

The driver is tested with:
	+ hwclock
	+ tools/testing/selftests/rtc/setdate
	+ tools/testing/selftests/rtc/rtctest

Signed-off-by: Tóth János <gomba007@gmail.com>
---
 MAINTAINERS                |   6 ++
 drivers/rtc/Kconfig        |  10 ++
 drivers/rtc/Makefile       |   1 +
 drivers/rtc/rtc-sd2405al.c | 227 +++++++++++++++++++++++++++++++++++++++++++++
 4 files changed, 244 insertions(+)

diff --git a/MAINTAINERS b/MAINTAINERS
index 8754ac2c259d..c78587811433 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -6337,6 +6337,12 @@ F:	include/net/devlink.h
 F:	include/uapi/linux/devlink.h
 F:	net/devlink/
 
+DFROBOT SD2405AL RTC DRIVER
+M:	Tóth János <gomba007@gmail.com>
+L:	linux-rtc@vger.kernel.org
+S:	Maintained
+F:	drivers/rtc/rtc-sd2405al.c
+
 DH ELECTRONICS IMX6 DHCOM/DHCOR BOARD SUPPORT
 M:	Christoph Niedermaier <cniedermaier@dh-electronics.com>
 L:	kernel@dh-electronics.com
diff --git a/drivers/rtc/Kconfig b/drivers/rtc/Kconfig
index 2a95b05982ad..15f1c0ba5759 100644
--- a/drivers/rtc/Kconfig
+++ b/drivers/rtc/Kconfig
@@ -743,6 +743,16 @@ config RTC_DRV_S5M
 	  This driver can also be built as a module. If so, the module
 	  will be called rtc-s5m.
 
+config RTC_DRV_SD2405AL
+	tristate "DFRobot SD2405AL"
+	select REGMAP_I2C
+	help
+	  If you say yes here you will get support for the
+	  DFRobot SD2405AL I2C RTC Module.
+
+	  This driver can also be built as a module. If so, the module
+	  will be called rtc-sd2405al.
+
 config RTC_DRV_SD3078
 	tristate "ZXW Shenzhen whwave SD3078"
 	select REGMAP_I2C
diff --git a/drivers/rtc/Makefile b/drivers/rtc/Makefile
index 3004e372f25f..3d19feba1e1c 100644
--- a/drivers/rtc/Makefile
+++ b/drivers/rtc/Makefile
@@ -162,6 +162,7 @@ obj-$(CONFIG_RTC_DRV_S3C)	+= rtc-s3c.o
 obj-$(CONFIG_RTC_DRV_S5M)	+= rtc-s5m.o
 obj-$(CONFIG_RTC_DRV_SA1100)	+= rtc-sa1100.o
 obj-$(CONFIG_RTC_DRV_SC27XX)	+= rtc-sc27xx.o
+obj-$(CONFIG_RTC_DRV_SD2405AL)	+= rtc-sd2405al.o
 obj-$(CONFIG_RTC_DRV_SD3078)   += rtc-sd3078.o
 obj-$(CONFIG_RTC_DRV_SH)	+= rtc-sh.o
 obj-$(CONFIG_RTC_DRV_SNVS)	+= rtc-snvs.o
diff --git a/drivers/rtc/rtc-sd2405al.c b/drivers/rtc/rtc-sd2405al.c
new file mode 100644
index 000000000000..d2568c3e3876
--- /dev/null
+++ b/drivers/rtc/rtc-sd2405al.c
@@ -0,0 +1,227 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * RTC driver for the SD2405AL Real-Time Clock
+ *
+ * Datasheet:
+ * https://image.dfrobot.com/image/data/TOY0021/SD2405AL%20datasheet%20(Angelo%20v0.1).pdf
+ *
+ * Copyright (C) 2024 Tóth János <gomba007@gmail.com>
+ */
+
+#include <linux/bcd.h>
+#include <linux/i2c.h>
+#include <linux/regmap.h>
+#include <linux/rtc.h>
+
+/* Real time clock registers */
+#define SD2405AL_REG_T_SEC	0x00
+#define SD2405AL_REG_T_MIN	0x01
+#define SD2405AL_REG_T_HOUR	0x02
+#	define SD2405AL_BIT_12H_PM	BIT(5)
+#	define SD2405AL_BIT_24H		BIT(7)
+#define SD2405AL_REG_T_WEEK	0x03
+#define SD2405AL_REG_T_DAY	0x04
+#define SD2405AL_REG_T_MON	0x05
+#define SD2405AL_REG_T_YEAR	0x06
+
+#define SD2405AL_NUM_T_REGS	(SD2405AL_REG_T_YEAR - SD2405AL_REG_T_SEC + 1)
+
+/* Control registers */
+#define SD2405AL_REG_CTR1	0x0F
+#	define SD2405AL_BIT_WRTC2	BIT(2)
+#	define SD2405AL_BIT_WRTC3	BIT(7)
+#define SD2405AL_REG_CTR2	0x10
+#	define SD2405AL_BIT_WRTC1	BIT(7)
+#define SD2405AL_REG_CTR3	0x11
+#define SD2405AL_REG_TTF	0x12
+#define SD2405AL_REG_CNTDWN	0x13
+
+/* General RAM */
+#define SD2405AL_REG_M_START	0x14
+#define SD2405AL_REG_M_END	0x1F
+
+struct sd2405al {
+	struct device		*dev;
+	struct rtc_device	*rtc;
+	struct regmap		*regmap;
+};
+
+static int sd2405al_enable_reg_write(struct sd2405al *sd2405al)
+{
+	int ret;
+
+	/* order of writes is important */
+	ret = regmap_update_bits(sd2405al->regmap, SD2405AL_REG_CTR2,
+				 SD2405AL_BIT_WRTC1, SD2405AL_BIT_WRTC1);
+	if (ret < 0)
+		return ret;
+
+	ret = regmap_update_bits(sd2405al->regmap, SD2405AL_REG_CTR1,
+				 SD2405AL_BIT_WRTC2 | SD2405AL_BIT_WRTC3,
+				 SD2405AL_BIT_WRTC2 | SD2405AL_BIT_WRTC3);
+	if (ret < 0)
+		return ret;
+
+	return 0;
+}
+
+static int sd2405al_disable_reg_write(struct sd2405al *sd2405al)
+{
+	int ret;
+
+	/* order of writes is important */
+	ret = regmap_update_bits(sd2405al->regmap, SD2405AL_REG_CTR1,
+				 SD2405AL_BIT_WRTC2 | SD2405AL_BIT_WRTC3, 0x00);
+	if (ret < 0)
+		return ret;
+
+	ret = regmap_update_bits(sd2405al->regmap, SD2405AL_REG_CTR2,
+				 SD2405AL_BIT_WRTC1, 0x00);
+	if (ret < 0)
+		return ret;
+
+	return 0;
+}
+
+static int sd2405al_read_time(struct device *dev, struct rtc_time *time)
+{
+	u8 data[SD2405AL_NUM_T_REGS] = { 0 };
+	struct sd2405al *sd2405al = dev_get_drvdata(dev);
+	int ret;
+
+	ret = regmap_bulk_read(sd2405al->regmap, SD2405AL_REG_T_SEC, data,
+			       SD2405AL_NUM_T_REGS);
+	if (ret < 0)
+		return ret;
+
+	time->tm_sec = bcd2bin(data[SD2405AL_REG_T_SEC] & 0x7F);
+	time->tm_min = bcd2bin(data[SD2405AL_REG_T_MIN] & 0x7F);
+
+	if (data[SD2405AL_REG_T_HOUR] & SD2405AL_BIT_24H)
+		time->tm_hour = bcd2bin(data[SD2405AL_REG_T_HOUR] & 0x3F);
+	else
+		if (data[SD2405AL_REG_T_HOUR] & SD2405AL_BIT_12H_PM)
+			time->tm_hour = bcd2bin(data[SD2405AL_REG_T_HOUR]
+						& 0x1F) + 12;
+		else /* 12 hour mode, AM */
+			time->tm_hour = bcd2bin(data[SD2405AL_REG_T_HOUR]
+						& 0x1F);
+
+	time->tm_wday = bcd2bin(data[SD2405AL_REG_T_WEEK] & 0x07);
+	time->tm_mday = bcd2bin(data[SD2405AL_REG_T_DAY] & 0x3F);
+	time->tm_mon = bcd2bin(data[SD2405AL_REG_T_MON] & 0x1F) - 1;
+	time->tm_year = bcd2bin(data[SD2405AL_REG_T_YEAR]) + 100;
+
+	dev_dbg(sd2405al->dev, "read time: %ptR (%d)\n", time, time->tm_wday);
+
+	return 0;
+}
+
+static int sd2405al_set_time(struct device *dev, struct rtc_time *time)
+{
+	u8 data[SD2405AL_NUM_T_REGS];
+	struct sd2405al *sd2405al = dev_get_drvdata(dev);
+	int ret;
+
+	data[SD2405AL_REG_T_SEC] = bin2bcd(time->tm_sec);
+	data[SD2405AL_REG_T_MIN] = bin2bcd(time->tm_min);
+	data[SD2405AL_REG_T_HOUR] = bin2bcd(time->tm_hour) | SD2405AL_BIT_24H;
+	data[SD2405AL_REG_T_DAY] = bin2bcd(time->tm_mday);
+	data[SD2405AL_REG_T_WEEK] = bin2bcd(time->tm_wday);
+	data[SD2405AL_REG_T_MON] = bin2bcd(time->tm_mon) + 1;
+	data[SD2405AL_REG_T_YEAR] = bin2bcd(time->tm_year - 100);
+
+	ret = sd2405al_enable_reg_write(sd2405al);
+	if (ret < 0)
+		return ret;
+
+	ret = regmap_bulk_write(sd2405al->regmap, SD2405AL_REG_T_SEC, data,
+				SD2405AL_NUM_T_REGS);
+	if (ret < 0)
+		return ret;
+
+	ret = regmap_write(sd2405al->regmap, SD2405AL_REG_TTF, 0x00);
+	if (ret < 0)
+		return ret;
+
+	ret = sd2405al_disable_reg_write(sd2405al);
+	if (ret < 0)
+		return ret;
+
+	dev_dbg(sd2405al->dev, "set time: %ptR (%d)\n", time, time->tm_wday);
+
+	return 0;
+}
+
+static const struct rtc_class_ops sd2405al_rtc_ops = {
+	.read_time = sd2405al_read_time,
+	.set_time = sd2405al_set_time,
+};
+
+static const struct regmap_config sd2405al_regmap_conf = {
+	.reg_bits = 8,
+	.val_bits = 8,
+	.max_register = SD2405AL_REG_M_END,
+};
+
+static int sd2405al_probe(struct i2c_client *client)
+{
+	struct sd2405al *sd2405al;
+	int ret;
+
+	if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
+		return -ENODEV;
+
+	sd2405al = devm_kzalloc(&client->dev, sizeof(*sd2405al), GFP_KERNEL);
+	if (!sd2405al)
+		return -ENOMEM;
+
+	sd2405al->dev = &client->dev;
+
+	sd2405al->regmap = devm_regmap_init_i2c(client, &sd2405al_regmap_conf);
+	if (IS_ERR(sd2405al->regmap))
+		return PTR_ERR(sd2405al->regmap);
+
+	sd2405al->rtc = devm_rtc_allocate_device(&client->dev);
+	if (IS_ERR(sd2405al->rtc))
+		return PTR_ERR(sd2405al->rtc);
+
+	sd2405al->rtc->ops = &sd2405al_rtc_ops;
+	sd2405al->rtc->range_min = RTC_TIMESTAMP_BEGIN_2000;
+	sd2405al->rtc->range_max = RTC_TIMESTAMP_END_2099;
+
+	dev_set_drvdata(&client->dev, sd2405al);
+
+	ret = devm_rtc_register_device(sd2405al->rtc);
+	if (ret < 0)
+		return ret;
+
+	return 0;
+}
+
+static const struct i2c_device_id sd2405al_id[] = {
+	{ "sd2405al" },
+	{ /* sentinel */ }
+};
+MODULE_DEVICE_TABLE(i2c, sd2405al_id);
+
+static const __maybe_unused struct of_device_id sd2405al_of_match[] = {
+	{ .compatible = "dfrobot,sd2405al" },
+	{ /* sentinel */ }
+};
+MODULE_DEVICE_TABLE(of, sd2405al_of_match);
+
+static struct i2c_driver sd2405al_driver = {
+	.driver = {
+		.name = "sd2405al",
+		.of_match_table = of_match_ptr(sd2405al_of_match),
+	},
+	.probe = sd2405al_probe,
+	.id_table = sd2405al_id,
+};
+
+module_i2c_driver(sd2405al_driver);
+
+MODULE_AUTHOR("Tóth János <gomba007@gmail.com>");
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("SD2405AL RTC driver");

-- 
2.34.1

[PATCH v5 2/2] dt-bindings: rtc: Add support for SD2405AL.

[Tóth János via B4 Relay]

From: Tóth János <gomba007@gmail.com>

Add the necessary documentation for SD2405AL.

Signed-off-by: Tóth János <gomba007@gmail.com>
---
 Documentation/devicetree/bindings/rtc/trivial-rtc.yaml | 2 ++
 Documentation/devicetree/bindings/vendor-prefixes.yaml | 2 ++
 2 files changed, 4 insertions(+)

diff --git a/Documentation/devicetree/bindings/rtc/trivial-rtc.yaml b/Documentation/devicetree/bindings/rtc/trivial-rtc.yaml
index fffd759c603f..dae594626b2e 100644
--- a/Documentation/devicetree/bindings/rtc/trivial-rtc.yaml
+++ b/Documentation/devicetree/bindings/rtc/trivial-rtc.yaml
@@ -38,6 +38,8 @@ properties:
       - dallas,ds1672
       # Extremely Accurate I²C RTC with Integrated Crystal and SRAM
       - dallas,ds3232
+      # SD2405AL Real-Time Clock
+      - dfrobot,sd2405al
       # EM Microelectronic EM3027 RTC
       - emmicro,em3027
       # I2C-BUS INTERFACE REAL TIME CLOCK MODULE
diff --git a/Documentation/devicetree/bindings/vendor-prefixes.yaml b/Documentation/devicetree/bindings/vendor-prefixes.yaml
index fbf47f0bacf1..eddc91129a2a 100644
--- a/Documentation/devicetree/bindings/vendor-prefixes.yaml
+++ b/Documentation/devicetree/bindings/vendor-prefixes.yaml
@@ -364,6 +364,8 @@ patternProperties:
     description: Devantech, Ltd.
   "^dfi,.*":
     description: DFI Inc.
+  "^dfrobot,.*":
+    description: DFRobot Corporation
   "^dh,.*":
     description: DH electronics GmbH
   "^difrnce,.*":

-- 
2.34.1

Re: [PATCH v5 2/2] dt-bindings: rtc: Add support for SD2405AL.

[Krzysztof Kozlowski]

On 28/08/2024 10:22, Tóth János via B4 Relay wrote:
> From: Tóth János <gomba007@gmail.com>
> 
> Add the necessary documentation for SD2405AL.
> 
> Signed-off-by: Tóth János <gomba007@gmail.com>
> ---

The patch is trivial but I don't understand why opting out of automated
testing. People still make mistakes in for example white-spaces, so no
review from me, sorry.

<form letter>
Please use scripts/get_maintainers.pl to get a list of necessary people
and lists to CC. It might happen, that command when run on an older
kernel, gives you outdated entries. Therefore please be sure you base
your patches on recent Linux kernel.

Tools like b4 or scripts/get_maintainer.pl provide you proper list of
people, so fix your workflow. Tools might also fail if you work on some
ancient tree (don't, instead use mainline) or work on fork of kernel
(don't, instead use mainline). Just use b4 and everything should be
fine, although remember about `b4 prep --auto-to-cc` if you added new
patches to the patchset.

You missed at least devicetree list (maybe more), so this won't be
tested by automated tooling. Performing review on untested code might be
a waste of time.

Please kindly resend and include all necessary To/Cc entries.
</form letter>

Best regards,
Krzysztof

Re: [PATCH v5 2/2] dt-bindings: rtc: Add support for SD2405AL.

[Tóth János]

Dear Krzysztof,

Thank you for the advice, and sorry for the inconvenience.

Best regards,
János