[PATCH v6 0/2] Add support for the DFRobot SD2405AL I2C RTC Module.

[PATCH v6 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.

To: Alexandre Belloni <alexandre.belloni@bootlin.com>
To: Rob Herring <robh@kernel.org>
To: Krzysztof Kozlowski <krzk+dt@kernel.org>
To: Conor Dooley <conor+dt@kernel.org>
Cc: linux-kernel@vger.kernel.org
Cc: linux-rtc@vger.kernel.org
Cc: csokas.bence@prolan.hu
Cc: devicetree@vger.kernel.org
Signed-off-by: Tóth János <gomba007@gmail.com>

Changes in v6:
- Add missing To-s and Cc-s.
- Rebased onto v6.11-rc5
- Link to v5: https://lore.kernel.org/r/20240828-rtc-sd2405al-v5-0-9e3f8fa5ea6b@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: 5be63fc19fcaa4c236b307420483578a56986a37
change-id: 20240607-rtc-sd2405al-a0947377c73d

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

[PATCH v6 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 878dcd23b331..cb4e5fcde44e 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -6476,6 +6476,12 @@ 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 v6 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 a70ce43b3dc0..bd8b279a5152 100644
--- a/Documentation/devicetree/bindings/vendor-prefixes.yaml
+++ b/Documentation/devicetree/bindings/vendor-prefixes.yaml
@@ -368,6 +368,8 @@ patternProperties:
     description: Devantech, Ltd.
   "^dfi,.*":
     description: DFI Inc.
+  "^dfrobot,.*":
+    description: DFRobot Corporation
   "^dh,.*":
     description: DH electronics GmbH
   "^difrnce,.*":

-- 
2.34.1

Re: [PATCH v6 2/2] dt-bindings: rtc: Add support for SD2405AL.

[Conor Dooley]

[-- Attachment #1: Type: text/plain, Size: 1914 bytes --]

On Thu, Aug 29, 2024 at 01:31:45PM +0200, 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>
> ---
>  Documentation/devicetree/bindings/rtc/trivial-rtc.yaml | 2 ++
>  Documentation/devicetree/bindings/vendor-prefixes.yaml | 2 ++

Both of these should really be two different patches, despite how
trivial they would be. If you resubmit, please do that and provide a
link to the vendor in the vendor-prefixes patch. Otherwise,
Acked-by: Conor Dooley <conor.dooley@microchip.com>

Thanks,
Conor.

>  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 a70ce43b3dc0..bd8b279a5152 100644
> --- a/Documentation/devicetree/bindings/vendor-prefixes.yaml
> +++ b/Documentation/devicetree/bindings/vendor-prefixes.yaml
> @@ -368,6 +368,8 @@ patternProperties:
>      description: Devantech, Ltd.
>    "^dfi,.*":
>      description: DFI Inc.
> +  "^dfrobot,.*":
> +    description: DFRobot Corporation
>    "^dh,.*":
>      description: DH electronics GmbH
>    "^difrnce,.*":
> 
> -- 
> 2.34.1
> 
> 

[-- Attachment #2: signature.asc --]
[-- Type: application/pgp-signature, Size: 228 bytes --]

Re: [PATCH v6 0/2] Add support for the DFRobot SD2405AL I2C RTC Module.

[Alexandre Belloni]

This looks good, can you send v7 adressint Conor's comment, don't forget
to collect his tag.

On 29/08/2024 13:31:43+0200, Tóth János via B4 Relay wrote:
> This patch series adds a driver and the documentation for the SD2405AL I2C RTC.
> 
> To: Alexandre Belloni <alexandre.belloni@bootlin.com>
> To: Rob Herring <robh@kernel.org>
> To: Krzysztof Kozlowski <krzk+dt@kernel.org>
> To: Conor Dooley <conor+dt@kernel.org>
> Cc: linux-kernel@vger.kernel.org
> Cc: linux-rtc@vger.kernel.org
> Cc: csokas.bence@prolan.hu
> Cc: devicetree@vger.kernel.org
> Signed-off-by: Tóth János <gomba007@gmail.com>
> 
> Changes in v6:
> - Add missing To-s and Cc-s.
> - Rebased onto v6.11-rc5
> - Link to v5: https://lore.kernel.org/r/20240828-rtc-sd2405al-v5-0-9e3f8fa5ea6b@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: 5be63fc19fcaa4c236b307420483578a56986a37
> change-id: 20240607-rtc-sd2405al-a0947377c73d
> 
> Best regards,
> -- 
> Tóth János <gomba007@gmail.com>
> 
> 

-- 
Alexandre Belloni, co-owner and COO, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com

Re: [PATCH v6 2/2] dt-bindings: rtc: Add support for SD2405AL.

[Tóth János]

Dear Conor,

thank you for your review!

> Both of these should really be two different patches

Sure, I'll split them.

> provide a link to the vendor in the vendor-prefixes patch.

Okay.

Regards,
János