rtc: add driver for Marvell 88PM886 PMIC RTC

RTC lives on the chip's base register page. Add the relevant register
definitions and implement a basic set/read time functionality. Tested
with the samsung,coreprimevelte smartphone which contains this PMIC and
whose vendor kernel tree has also served as the sole reference for this.

Signed-off-by: Karel Balej <balejk@matfyz.cz>
Acked-by: Lee Jones <lee@kernel.org>
Link: https://lore.kernel.org/r/20241012193345.18594-2-balejk@matfyz.cz
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>

diff --git a/MAINTAINERS b/MAINTAINERS
index ef0a949c380d9d9b9f0851bb12096843baf0e9ae..054425c4afd2801a666968ae8595f5f4ab61abe5 100644 (file)
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -13706,6 +13706,7 @@ F:      Documentation/devicetree/bindings/mfd/marvell,88pm886-a1.yaml
 F:     drivers/input/misc/88pm886-onkey.c
 F:     drivers/mfd/88pm886.c
 F:     drivers/regulator/88pm886-regulator.c
+F:     drivers/rtc/rtc-88pm886.c
 F:     include/linux/mfd/88pm886.h
 
 MARVELL ARMADA 3700 PHY DRIVERS

diff --git a/drivers/rtc/Kconfig b/drivers/rtc/Kconfig
index 0e6e0b8b45f71d775f4489278b2035b4c4b3caee..e1153ed25b3fef5aed98f28328955c7d2cd6375a 100644 (file)
--- a/drivers/rtc/Kconfig
+++ b/drivers/rtc/Kconfig
@@ -182,6 +182,16 @@ config RTC_DRV_88PM80X
          This driver can also be built as a module. If so, the module
          will be called rtc-88pm80x.
 
+config RTC_DRV_88PM886
+       tristate "Marvell 88PM886 RTC driver"
+       depends on MFD_88PM886_PMIC
+       help
+         If you say yes here you will get support for the RTC function in the
+         Marvell 88PM886 chip.
+
+         This driver can also be built as a module. If so, the module
+         will be called rtc-88pm886.
+
 config RTC_DRV_ABB5ZES3
        select REGMAP_I2C
        tristate "Abracon AB-RTCMC-32.768kHz-B5ZE-S3"

diff --git a/drivers/rtc/Makefile b/drivers/rtc/Makefile
index b0dc6b6485705e3c675f5cc1768e20a85d94eb37..411016668753d885ea77072e56b9fdb61775da1a 100644 (file)
--- a/drivers/rtc/Makefile
+++ b/drivers/rtc/Makefile
@@ -21,6 +21,7 @@ obj-$(CONFIG_RTC_LIB_KUNIT_TEST)      += lib_test.o
 
 obj-$(CONFIG_RTC_DRV_88PM80X)  += rtc-88pm80x.o
 obj-$(CONFIG_RTC_DRV_88PM860X) += rtc-88pm860x.o
+obj-$(CONFIG_RTC_DRV_88PM886)  += rtc-88pm886.o
 obj-$(CONFIG_RTC_DRV_AB8500)   += rtc-ab8500.o
 obj-$(CONFIG_RTC_DRV_ABB5ZES3) += rtc-ab-b5ze-s3.o
 obj-$(CONFIG_RTC_DRV_ABEOZ9)   += rtc-ab-eoz9.o

diff --git a/drivers/rtc/rtc-88pm886.c b/drivers/rtc/rtc-88pm886.c
new file mode 100644 (file)
index 0000000..57e9b0a
--- /dev/null
+++ b/drivers/rtc/rtc-88pm886.c
@@ -0,0 +1,97 @@
+// SPDX-License-Identifier: GPL-2.0-only
+#include <linux/limits.h>
+#include <linux/mod_devicetable.h>
+#include <linux/platform_device.h>
+#include <linux/rtc.h>
+
+#include <linux/mfd/88pm886.h>
+
+/*
+ * Time is calculated as the sum of a 32-bit read-only advancing counter and a
+ * writeable constant offset stored in the chip's spare registers.
+ */
+
+static int pm886_rtc_read_time(struct device *dev, struct rtc_time *tm)
+{
+       struct regmap *regmap = dev_get_drvdata(dev);
+       u32 time;
+       u32 buf;
+       int ret;
+
+       ret = regmap_bulk_read(regmap, PM886_REG_RTC_SPARE1, &buf, 4);
+       if (ret)
+               return ret;
+       time = buf;
+
+       ret = regmap_bulk_read(regmap, PM886_REG_RTC_CNT1, &buf, 4);
+       if (ret)
+               return ret;
+       time += buf;
+
+       rtc_time64_to_tm(time, tm);
+
+       return 0;
+}
+
+static int pm886_rtc_set_time(struct device *dev, struct rtc_time *tm)
+{
+       struct regmap *regmap = dev_get_drvdata(dev);
+       u32 buf;
+       int ret;
+
+       ret = regmap_bulk_read(regmap, PM886_REG_RTC_CNT1, &buf, 4);
+       if (ret)
+               return ret;
+
+       buf = rtc_tm_to_time64(tm) - buf;
+
+       return regmap_bulk_write(regmap, PM886_REG_RTC_SPARE1, &buf, 4);
+}
+
+static const struct rtc_class_ops pm886_rtc_ops = {
+       .read_time = pm886_rtc_read_time,
+       .set_time = pm886_rtc_set_time,
+};
+
+static int pm886_rtc_probe(struct platform_device *pdev)
+{
+       struct pm886_chip *chip = dev_get_drvdata(pdev->dev.parent);
+       struct device *dev = &pdev->dev;
+       struct rtc_device *rtc;
+       int ret;
+
+       platform_set_drvdata(pdev, chip->regmap);
+
+       rtc = devm_rtc_allocate_device(dev);
+       if (IS_ERR(rtc))
+               return dev_err_probe(dev, PTR_ERR(rtc),
+                               "Failed to allocate RTC device\n");
+
+       rtc->ops = &pm886_rtc_ops;
+       rtc->range_max = U32_MAX;
+
+       ret = devm_rtc_register_device(rtc);
+       if (ret)
+               return dev_err_probe(dev, ret, "Failed to register RTC device\n");
+
+       return 0;
+}
+
+static const struct platform_device_id pm886_rtc_id_table[] = {
+       { "88pm886-rtc", },
+       { }
+};
+MODULE_DEVICE_TABLE(platform, pm886_rtc_id_table);
+
+static struct platform_driver pm886_rtc_driver = {
+       .driver = {
+               .name = "88pm886-rtc",
+       },
+       .probe = pm886_rtc_probe,
+       .id_table = pm886_rtc_id_table,
+};
+module_platform_driver(pm886_rtc_driver);
+
+MODULE_DESCRIPTION("Marvell 88PM886 RTC driver");
+MODULE_AUTHOR("Karel Balej <balejk@matfyz.cz>");
+MODULE_LICENSE("GPL");

diff --git a/include/linux/mfd/88pm886.h b/include/linux/mfd/88pm886.h
index 133aa302e49297fd923d0eb41146da69f5f2c5eb..85eca44f39ab58ba4cb9ec4216118ee9604d021f 100644 (file)
--- a/include/linux/mfd/88pm886.h
+++ b/include/linux/mfd/88pm886.h
@@ -31,6 +31,15 @@
 #define PM886_INT_WC                   BIT(1)
 #define PM886_INT_MASK_MODE            BIT(2)
 
+#define PM886_REG_RTC_CNT1             0xd1
+#define PM886_REG_RTC_CNT2             0xd2
+#define PM886_REG_RTC_CNT3             0xd3
+#define PM886_REG_RTC_CNT4             0xd4
+#define PM886_REG_RTC_SPARE1           0xea
+#define PM886_REG_RTC_SPARE2           0xeb
+#define PM886_REG_RTC_SPARE3           0xec
+#define PM886_REG_RTC_SPARE4           0xed
+#define PM886_REG_RTC_SPARE5           0xee
 #define PM886_REG_RTC_SPARE6           0xef
 
 #define PM886_REG_BUCK_EN              0x08