The sd3078 is a combination RTC and SRAM device with I2C interface.
Signed-off-by: Dianlong Li
---
MAINTAINERS |6 ++
drivers/rtc/Kconfig |9 ++
drivers/rtc/Makefile |1 +
drivers/rtc/rtc-sd3078.c | 232 ++
4 files changed, 248 insertions(+)
create mode 100644 drivers/rtc/rtc-sd3078.c
diff --git a/MAINTAINERS b/MAINTAINERS
index f485597..2ad8671 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -16125,6 +16125,12 @@ L: linux-g...@vger.kernel.org
S: Maintained
F: drivers/gpio/gpio-wcove.c
+WHWAVE RTC DRIVER
+M: Dianlong Li
+L: linux-...@vger.kernel.org
+S: Maintained
+F: drivers/rtc/rtc-sd3078.c
+
WIIMOTE HID DRIVER
M: David Herrmann
L: linux-in...@vger.kernel.org
diff --git a/drivers/rtc/Kconfig b/drivers/rtc/Kconfig
index a819ef0..51a8255b 100644
--- a/drivers/rtc/Kconfig
+++ b/drivers/rtc/Kconfig
@@ -646,6 +646,15 @@ 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_SD3078
+tristate "ZXW Crystal SD3078"
+help
+ If you say yes here you get support for the ZXW Crystal
+ SD3078 RTC chips.
+
+ This driver can also be built as a module. If so, the module
+ will be called rtc-sd3078
+
endif # I2C
comment "SPI RTC drivers"
diff --git a/drivers/rtc/Makefile b/drivers/rtc/Makefile
index 290c173..91a9257 100644
--- a/drivers/rtc/Makefile
+++ b/drivers/rtc/Makefile
@@ -148,6 +148,7 @@ 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-$(CONFIG_RTC_DRV_SD3078) += rtc-sd3078.o
obj-$(CONFIG_RTC_DRV_SH) += rtc-sh.o
obj-$(CONFIG_RTC_DRV_SIRFSOC) += rtc-sirfsoc.o
obj-$(CONFIG_RTC_DRV_SNVS) += rtc-snvs.o
diff --git a/drivers/rtc/rtc-sd3078.c b/drivers/rtc/rtc-sd3078.c
new file mode 100644
index 000..a70d7311
--- /dev/null
+++ b/drivers/rtc/rtc-sd3078.c
@@ -0,0 +1,232 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Real Time Clock (RTC) Driver for sd3078
+ * Copyright (C) 2018 Zoro Li
+ */
+
+#include
+#include
+#include
+#include
+#include
+#include
+
+#define SD3078_REG_SC 0x00
+#define SD3078_REG_MN 0x01
+#define SD3078_REG_HR 0x02
+#define SD3078_REG_DW 0x03
+#define SD3078_REG_DM 0x04
+#define SD3078_REG_MO 0x05
+#define SD3078_REG_YR 0x06
+
+#define SD3078_REG_CTRL1 0x0f
+#define SD3078_REG_CTRL2 0x10
+#define SD3078_REG_CTRL3 0x11
+
+#define KEY_WRITE1 0x80
+#define KEY_WRITE2 0x04
+#define KEY_WRITE3 0x80
+
+#define NUM_TIME_REGS (SD3078_REG_YR - SD3078_REG_SC + 1)
+
+/*
+ * The sd3078 has write protection
+ * and we can choose whether or not to use it.
+ * Write protection is turned off by default.
+ */
+#define WRITE_PROTECT_EN 0
+
+struct sd3078 {
+ struct rtc_device *rtc;
+ struct regmap *regmap;
+};
+
+/*
+ * In order to prevent arbitrary modification of the time register,
+ * when modification of the register,
+ * the "write" bit needs to be written in a certain order.
+ * 1. set WRITE1 bit
+ * 2. set WRITE2 bit
+ * 3. set WRITE3 bit
+ */
+static void sd3078_enable_reg_write(struct sd3078 *sd3078)
+{
+ regmap_update_bits(sd3078->regmap, SD3078_REG_CTRL2,
+ KEY_WRITE1, KEY_WRITE1);
+ regmap_update_bits(sd3078->regmap, SD3078_REG_CTRL1,
+ KEY_WRITE2, KEY_WRITE2);
+ regmap_update_bits(sd3078->regmap, SD3078_REG_CTRL1,
+ KEY_WRITE3, KEY_WRITE3);
+}
+
+#if WRITE_PROTECT_EN
+/*
+ * In order to prevent arbitrary modification of the time register,
+ * we should disable the write function.
+ * when disable write,
+ * the "write" bit needs to be clear in a certain order.
+ * 1. clear WRITE2 bit
+ * 2. clear WRITE3 bit
+ * 3. clear WRITE1 bit
+ */
+static void sd3078_disable_reg_write(struct sd3078 *sd3078)
+{
+ regmap_update_bits(sd3078->regmap, SD3078_REG_CTRL1,
+ KEY_WRITE2, 0);
+ regmap_update_bits(sd3078->regmap, SD3078_REG_CTRL1,
+ KEY_WRITE3, 0);
+ regmap_update_bits(sd3078->regmap, SD3078_REG_CTRL2,
+ KEY_WRITE1, 0);
+}
+#endif
+
+static int sd3078_rtc_read_time(struct device *dev, struct rtc_time *tm)
+{
+ unsigned char hour;
+ unsigned char rtc_data[NUM_TIME_REGS] = {0};
+ struct i2c_client *client = to_i2c_client(dev);
+ struct sd3078 *sd3078 = i2c_get_clientdata(client);
+ int ret;
+
+ ret = regmap_bulk_read(sd3078->regmap, SD3078_REG_SC, rtc_data,
+ NUM_TIME_REGS);
