rtc: support i.MX95 BBM RTC

The BBM module provides RTC feature. To i.MX95, this module is managed by
System Manager and exported System Control Management Interface(SCMI).
Linux could use i.MX SCMI BBM Extension protocol to use RTC feature.

This driver is to use SCMI interface to get/set RTC.

Reviewed-by: Cristian Marussi <cristian.marussi@arm.com>
Signed-off-by: Peng Fan <peng.fan@nxp.com>
Message-Id: <20240823-imx95-bbm-misc-v2-v8-6-e600ed9e9271@nxp.com>
Acked-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

drivers/rtc/Kconfig

@@ -1827,6 +1827,17 @@ config RTC_DRV_BBNSM
 	   This driver can also be built as a module, if so, the module
 	   will be called "rtc-bbnsm".
 
+config RTC_DRV_IMX_BBM_SCMI
+	depends on IMX_SCMI_BBM_EXT || COMPILE_TEST
+	default y if ARCH_MXC
+	tristate "NXP i.MX BBM SCMI RTC support"
+	help
+	  If you say yes here you get support for the NXP i.MX BBSM SCMI
+	  RTC module.
+
+	  To compile this driver as a module, choose M here: the
+	  module will be called rtc-imx-sm-bbm.
+
 config RTC_DRV_IMX_SC
 	depends on IMX_SCU
 	depends on HAVE_ARM_SMCCC

drivers/rtc/Makefile

@@ -74,6 +74,7 @@ obj-$(CONFIG_RTC_DRV_HID_SENSOR_TIME) += rtc-hid-sensor-time.o
 obj-$(CONFIG_RTC_DRV_HYM8563)	+= rtc-hym8563.o
 obj-$(CONFIG_RTC_DRV_IMXDI)	+= rtc-imxdi.o
 obj-$(CONFIG_RTC_DRV_IMX_SC)	+= rtc-imx-sc.o
+obj-$(CONFIG_RTC_DRV_IMX_BBM_SCMI)	+= rtc-imx-sm-bbm.o
 obj-$(CONFIG_RTC_DRV_ISL12022)	+= rtc-isl12022.o
 obj-$(CONFIG_RTC_DRV_ISL12026)	+= rtc-isl12026.o
 obj-$(CONFIG_RTC_DRV_ISL1208)	+= rtc-isl1208.o

drivers/rtc/rtc-imx-sm-bbm.c

@@ -0,0 +1,162 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Copyright 2024 NXP.
+ */
+
+#include <linux/jiffies.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/rtc.h>
+#include <linux/scmi_protocol.h>
+#include <linux/scmi_imx_protocol.h>
+
+struct scmi_imx_bbm {
+	const struct scmi_imx_bbm_proto_ops *ops;
+	struct rtc_device *rtc_dev;
+	struct scmi_protocol_handle *ph;
+	struct notifier_block nb;
+};
+
+static int scmi_imx_bbm_read_time(struct device *dev, struct rtc_time *tm)
+{
+	struct scmi_imx_bbm *bbnsm = dev_get_drvdata(dev);
+	struct scmi_protocol_handle *ph = bbnsm->ph;
+	u64 val;
+	int ret;
+
+	ret = bbnsm->ops->rtc_time_get(ph, 0, &val);
+	if (ret)
+		return ret;
+
+	rtc_time64_to_tm(val, tm);
+
+	return 0;
+}
+
+static int scmi_imx_bbm_set_time(struct device *dev, struct rtc_time *tm)
+{
+	struct scmi_imx_bbm *bbnsm = dev_get_drvdata(dev);
+	struct scmi_protocol_handle *ph = bbnsm->ph;
+	u64 val;
+
+	val = rtc_tm_to_time64(tm);
+
+	return bbnsm->ops->rtc_time_set(ph, 0, val);
+}
+
+static int scmi_imx_bbm_alarm_irq_enable(struct device *dev, unsigned int enable)
+{
+	struct scmi_imx_bbm *bbnsm = dev_get_drvdata(dev);
+	struct scmi_protocol_handle *ph = bbnsm->ph;
+
+	/* scmi_imx_bbm_set_alarm enables the irq, just handle disable here */
+	if (!enable)
+		return bbnsm->ops->rtc_alarm_set(ph, 0, false, 0);
+
+	return 0;
+}
+
+static int scmi_imx_bbm_set_alarm(struct device *dev, struct rtc_wkalrm *alrm)
+{
+	struct scmi_imx_bbm *bbnsm = dev_get_drvdata(dev);
+	struct scmi_protocol_handle *ph = bbnsm->ph;
+	struct rtc_time *alrm_tm = &alrm->time;
+	u64 val;
+
+	val = rtc_tm_to_time64(alrm_tm);
+
+	return bbnsm->ops->rtc_alarm_set(ph, 0, true, val);
+}
+
+static const struct rtc_class_ops smci_imx_bbm_rtc_ops = {
+	.read_time = scmi_imx_bbm_read_time,
+	.set_time = scmi_imx_bbm_set_time,
+	.set_alarm = scmi_imx_bbm_set_alarm,
+	.alarm_irq_enable = scmi_imx_bbm_alarm_irq_enable,
+};
+
+static int scmi_imx_bbm_rtc_notifier(struct notifier_block *nb, unsigned long event, void *data)
+{
+	struct scmi_imx_bbm *bbnsm = container_of(nb, struct scmi_imx_bbm, nb);
+	struct scmi_imx_bbm_notif_report *r = data;
+
+	if (r->is_rtc)
+		rtc_update_irq(bbnsm->rtc_dev, 1, RTC_AF | RTC_IRQF);
+	else
+		pr_err("Unexpected bbm event: %s\n", __func__);
+
+	return 0;
+}
+
+static int scmi_imx_bbm_rtc_init(struct scmi_device *sdev)
+{
+	const struct scmi_handle *handle = sdev->handle;
+	struct device *dev = &sdev->dev;
+	struct scmi_imx_bbm *bbnsm = dev_get_drvdata(dev);
+	int ret;
+
+	bbnsm->rtc_dev = devm_rtc_allocate_device(dev);
+	if (IS_ERR(bbnsm->rtc_dev))
+		return PTR_ERR(bbnsm->rtc_dev);
+
+	bbnsm->rtc_dev->ops = &smci_imx_bbm_rtc_ops;
+	bbnsm->rtc_dev->range_max = U32_MAX;
+
+	bbnsm->nb.notifier_call = &scmi_imx_bbm_rtc_notifier;
+	ret = handle->notify_ops->devm_event_notifier_register(sdev, SCMI_PROTOCOL_IMX_BBM,
+							       SCMI_EVENT_IMX_BBM_RTC,
+							       NULL, &bbnsm->nb);
+	if (ret)
+		return ret;
+
+	return devm_rtc_register_device(bbnsm->rtc_dev);
+}
+
+static int scmi_imx_bbm_rtc_probe(struct scmi_device *sdev)
+{
+	const struct scmi_handle *handle = sdev->handle;
+	struct device *dev = &sdev->dev;
+	struct scmi_protocol_handle *ph;
+	struct scmi_imx_bbm *bbnsm;
+	int ret;
+
+	if (!handle)
+		return -ENODEV;
+
+	bbnsm = devm_kzalloc(dev, sizeof(*bbnsm), GFP_KERNEL);
+	if (!bbnsm)
+		return -ENOMEM;
+
+	bbnsm->ops = handle->devm_protocol_get(sdev, SCMI_PROTOCOL_IMX_BBM, &ph);
+	if (IS_ERR(bbnsm->ops))
+		return PTR_ERR(bbnsm->ops);
+
+	bbnsm->ph = ph;
+
+	device_init_wakeup(dev, true);
+
+	dev_set_drvdata(dev, bbnsm);
+
+	ret = scmi_imx_bbm_rtc_init(sdev);
+	if (ret)
+		device_init_wakeup(dev, false);
+
+	return ret;
+}
+
+static const struct scmi_device_id scmi_id_table[] = {
+	{ SCMI_PROTOCOL_IMX_BBM, "imx-bbm-rtc" },
+	{ },
+};
+MODULE_DEVICE_TABLE(scmi, scmi_id_table);
+
+static struct scmi_driver scmi_imx_bbm_rtc_driver = {
+	.name = "scmi-imx-bbm-rtc",
+	.probe = scmi_imx_bbm_rtc_probe,
+	.id_table = scmi_id_table,
+};
+module_scmi_driver(scmi_imx_bbm_rtc_driver);
+
+MODULE_AUTHOR("Peng Fan <peng.fan@nxp.com>");
+MODULE_DESCRIPTION("IMX SM BBM RTC driver");
+MODULE_LICENSE("GPL");