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rtc: Add driver for SD2405AL
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 Reviewed-by: Csókás Bence <csokas.bence@prolan.hu> Signed-off-by: Tóth János <gomba007@gmail.com> Link: https://lore.kernel.org/r/20240830-rtc-sd2405al-v7-1-2f7102621b1d@gmail.com Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
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‎MAINTAINERS

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@@ -6474,6 +6474,12 @@ F: include/net/devlink.h
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F: include/uapi/linux/devlink.h
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F: net/devlink/
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DFROBOT SD2405AL RTC DRIVER
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M: Tóth János <gomba007@gmail.com>
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L: linux-rtc@vger.kernel.org
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S: Maintained
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F: drivers/rtc/rtc-sd2405al.c
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DH ELECTRONICS IMX6 DHCOM/DHCOR BOARD SUPPORT
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M: Christoph Niedermaier <cniedermaier@dh-electronics.com>
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L: kernel@dh-electronics.com

‎drivers/rtc/Kconfig

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@@ -743,6 +743,16 @@ config RTC_DRV_S5M
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This driver can also be built as a module. If so, the module
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will be called rtc-s5m.
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config RTC_DRV_SD2405AL
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tristate "DFRobot SD2405AL"
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select REGMAP_I2C
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help
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If you say yes here you will get support for the
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DFRobot SD2405AL I2C RTC Module.
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This driver can also be built as a module. If so, the module
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will be called rtc-sd2405al.
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config RTC_DRV_SD3078
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tristate "ZXW Shenzhen whwave SD3078"
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select REGMAP_I2C

‎drivers/rtc/Makefile

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@@ -162,6 +162,7 @@ obj-$(CONFIG_RTC_DRV_S3C) += rtc-s3c.o
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obj-$(CONFIG_RTC_DRV_S5M) += rtc-s5m.o
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obj-$(CONFIG_RTC_DRV_SA1100) += rtc-sa1100.o
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obj-$(CONFIG_RTC_DRV_SC27XX) += rtc-sc27xx.o
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obj-$(CONFIG_RTC_DRV_SD2405AL) += rtc-sd2405al.o
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obj-$(CONFIG_RTC_DRV_SD3078) += rtc-sd3078.o
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obj-$(CONFIG_RTC_DRV_SH) += rtc-sh.o
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obj-$(CONFIG_RTC_DRV_SNVS) += rtc-snvs.o

‎drivers/rtc/rtc-sd2405al.c

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// SPDX-License-Identifier: GPL-2.0-or-later
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/*
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* RTC driver for the SD2405AL Real-Time Clock
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*
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* Datasheet:
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* https://image.dfrobot.com/image/data/TOY0021/SD2405AL%20datasheet%20(Angelo%20v0.1).pdf
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*
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* Copyright (C) 2024 Tóth János <gomba007@gmail.com>
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*/
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#include <linux/bcd.h>
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#include <linux/i2c.h>
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#include <linux/regmap.h>
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#include <linux/rtc.h>
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/* Real time clock registers */
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#define SD2405AL_REG_T_SEC 0x00
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#define SD2405AL_REG_T_MIN 0x01
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#define SD2405AL_REG_T_HOUR 0x02
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# define SD2405AL_BIT_12H_PM BIT(5)
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# define SD2405AL_BIT_24H BIT(7)
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#define SD2405AL_REG_T_WEEK 0x03
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#define SD2405AL_REG_T_DAY 0x04
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#define SD2405AL_REG_T_MON 0x05
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#define SD2405AL_REG_T_YEAR 0x06
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#define SD2405AL_NUM_T_REGS (SD2405AL_REG_T_YEAR - SD2405AL_REG_T_SEC + 1)
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/* Control registers */
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#define SD2405AL_REG_CTR1 0x0F
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# define SD2405AL_BIT_WRTC2 BIT(2)
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# define SD2405AL_BIT_WRTC3 BIT(7)
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#define SD2405AL_REG_CTR2 0x10
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# define SD2405AL_BIT_WRTC1 BIT(7)
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#define SD2405AL_REG_CTR3 0x11
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#define SD2405AL_REG_TTF 0x12
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#define SD2405AL_REG_CNTDWN 0x13
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/* General RAM */
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#define SD2405AL_REG_M_START 0x14
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#define SD2405AL_REG_M_END 0x1F
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struct sd2405al {
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struct device *dev;
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struct rtc_device *rtc;
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struct regmap *regmap;
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};
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static int sd2405al_enable_reg_write(struct sd2405al *sd2405al)
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{
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int ret;
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/* order of writes is important */
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ret = regmap_update_bits(sd2405al->regmap, SD2405AL_REG_CTR2,
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SD2405AL_BIT_WRTC1, SD2405AL_BIT_WRTC1);
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if (ret < 0)
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return ret;
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ret = regmap_update_bits(sd2405al->regmap, SD2405AL_REG_CTR1,
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SD2405AL_BIT_WRTC2 | SD2405AL_BIT_WRTC3,
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SD2405AL_BIT_WRTC2 | SD2405AL_BIT_WRTC3);
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if (ret < 0)
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return ret;
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return 0;
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}
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static int sd2405al_disable_reg_write(struct sd2405al *sd2405al)
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{
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int ret;
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/* order of writes is important */
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ret = regmap_update_bits(sd2405al->regmap, SD2405AL_REG_CTR1,
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SD2405AL_BIT_WRTC2 | SD2405AL_BIT_WRTC3, 0x00);
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if (ret < 0)
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return ret;
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ret = regmap_update_bits(sd2405al->regmap, SD2405AL_REG_CTR2,
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SD2405AL_BIT_WRTC1, 0x00);
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if (ret < 0)
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return ret;
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return 0;
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}
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static int sd2405al_read_time(struct device *dev, struct rtc_time *time)
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{
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u8 data[SD2405AL_NUM_T_REGS] = { 0 };
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struct sd2405al *sd2405al = dev_get_drvdata(dev);
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int ret;
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ret = regmap_bulk_read(sd2405al->regmap, SD2405AL_REG_T_SEC, data,
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SD2405AL_NUM_T_REGS);
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if (ret < 0)
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return ret;
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time->tm_sec = bcd2bin(data[SD2405AL_REG_T_SEC] & 0x7F);
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time->tm_min = bcd2bin(data[SD2405AL_REG_T_MIN] & 0x7F);
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if (data[SD2405AL_REG_T_HOUR] & SD2405AL_BIT_24H)
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time->tm_hour = bcd2bin(data[SD2405AL_REG_T_HOUR] & 0x3F);
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else
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if (data[SD2405AL_REG_T_HOUR] & SD2405AL_BIT_12H_PM)
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time->tm_hour = bcd2bin(data[SD2405AL_REG_T_HOUR]
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& 0x1F) + 12;
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else /* 12 hour mode, AM */
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time->tm_hour = bcd2bin(data[SD2405AL_REG_T_HOUR]
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& 0x1F);
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time->tm_wday = bcd2bin(data[SD2405AL_REG_T_WEEK] & 0x07);
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time->tm_mday = bcd2bin(data[SD2405AL_REG_T_DAY] & 0x3F);
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time->tm_mon = bcd2bin(data[SD2405AL_REG_T_MON] & 0x1F) - 1;
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time->tm_year = bcd2bin(data[SD2405AL_REG_T_YEAR]) + 100;
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dev_dbg(sd2405al->dev, "read time: %ptR (%d)\n", time, time->tm_wday);
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return 0;
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}
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static int sd2405al_set_time(struct device *dev, struct rtc_time *time)
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{
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u8 data[SD2405AL_NUM_T_REGS];
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struct sd2405al *sd2405al = dev_get_drvdata(dev);
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int ret;
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data[SD2405AL_REG_T_SEC] = bin2bcd(time->tm_sec);
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data[SD2405AL_REG_T_MIN] = bin2bcd(time->tm_min);
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data[SD2405AL_REG_T_HOUR] = bin2bcd(time->tm_hour) | SD2405AL_BIT_24H;
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data[SD2405AL_REG_T_DAY] = bin2bcd(time->tm_mday);
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data[SD2405AL_REG_T_WEEK] = bin2bcd(time->tm_wday);
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data[SD2405AL_REG_T_MON] = bin2bcd(time->tm_mon) + 1;
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data[SD2405AL_REG_T_YEAR] = bin2bcd(time->tm_year - 100);
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ret = sd2405al_enable_reg_write(sd2405al);
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if (ret < 0)
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return ret;
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ret = regmap_bulk_write(sd2405al->regmap, SD2405AL_REG_T_SEC, data,
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SD2405AL_NUM_T_REGS);
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if (ret < 0)
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return ret;
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ret = regmap_write(sd2405al->regmap, SD2405AL_REG_TTF, 0x00);
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if (ret < 0)
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return ret;
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ret = sd2405al_disable_reg_write(sd2405al);
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if (ret < 0)
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return ret;
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dev_dbg(sd2405al->dev, "set time: %ptR (%d)\n", time, time->tm_wday);
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return 0;
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}
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static const struct rtc_class_ops sd2405al_rtc_ops = {
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.read_time = sd2405al_read_time,
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.set_time = sd2405al_set_time,
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};
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static const struct regmap_config sd2405al_regmap_conf = {
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.reg_bits = 8,
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.val_bits = 8,
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.max_register = SD2405AL_REG_M_END,
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};
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static int sd2405al_probe(struct i2c_client *client)
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{
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struct sd2405al *sd2405al;
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int ret;
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if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
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return -ENODEV;
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sd2405al = devm_kzalloc(&client->dev, sizeof(*sd2405al), GFP_KERNEL);
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if (!sd2405al)
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return -ENOMEM;
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sd2405al->dev = &client->dev;
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sd2405al->regmap = devm_regmap_init_i2c(client, &sd2405al_regmap_conf);
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if (IS_ERR(sd2405al->regmap))
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return PTR_ERR(sd2405al->regmap);
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sd2405al->rtc = devm_rtc_allocate_device(&client->dev);
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if (IS_ERR(sd2405al->rtc))
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return PTR_ERR(sd2405al->rtc);
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sd2405al->rtc->ops = &sd2405al_rtc_ops;
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sd2405al->rtc->range_min = RTC_TIMESTAMP_BEGIN_2000;
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sd2405al->rtc->range_max = RTC_TIMESTAMP_END_2099;
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dev_set_drvdata(&client->dev, sd2405al);
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ret = devm_rtc_register_device(sd2405al->rtc);
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if (ret < 0)
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return ret;
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return 0;
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}
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static const struct i2c_device_id sd2405al_id[] = {
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{ "sd2405al" },
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{ /* sentinel */ }
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};
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MODULE_DEVICE_TABLE(i2c, sd2405al_id);
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static const __maybe_unused struct of_device_id sd2405al_of_match[] = {
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{ .compatible = "dfrobot,sd2405al" },
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{ /* sentinel */ }
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};
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MODULE_DEVICE_TABLE(of, sd2405al_of_match);
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static struct i2c_driver sd2405al_driver = {
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.driver = {
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.name = "sd2405al",
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.of_match_table = of_match_ptr(sd2405al_of_match),
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},
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.probe = sd2405al_probe,
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.id_table = sd2405al_id,
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};
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module_i2c_driver(sd2405al_driver);
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MODULE_AUTHOR("Tóth János <gomba007@gmail.com>");
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MODULE_LICENSE("GPL");
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MODULE_DESCRIPTION("SD2405AL RTC driver");

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