[PATCH v2 02/11] mfd: renesas-vbattb: Add a MFD driver for the Renesas VBATTB IP

[Claudiu]

From: Claudiu Beznea <claudiu.beznea.uj at bp.renesas.com>

Renesas VBATTB IP has logic to control the RTC clock, tamper detection
and a small 128B memory. Add a MFD driver to do the basic initialization
of the VBATTB IP for the inner components to work.

Signed-off-by: Claudiu Beznea <claudiu.beznea.uj at bp.renesas.com>
---

Changes in v2:
- none; this driver is new

 drivers/mfd/Kconfig          |  8 ++++
 drivers/mfd/Makefile         |  1 +
 drivers/mfd/renesas-vbattb.c | 78 ++++++++++++++++++++++++++++++++++++
 3 files changed, 87 insertions(+)
 create mode 100644 drivers/mfd/renesas-vbattb.c

diff --git a/drivers/mfd/Kconfig b/drivers/mfd/Kconfig
index bc8be2e593b6..df93e8b05065 100644
--- a/drivers/mfd/Kconfig
+++ b/drivers/mfd/Kconfig
@@ -1383,6 +1383,14 @@ config MFD_SC27XX_PMIC
 	  This driver provides common support for accessing the SC27xx PMICs,
 	  and it also adds the irq_chip parts for handling the PMIC chip events.
 
+config MFD_RENESAS_VBATTB
+	tristate "Renesas VBATTB driver"
+	depends on (ARCH_RZG2L && OF) || COMPILE_TEST
+	select MFD_CORE
+	help
+	  Select this option to enable Renesas RZ/G3S VBATTB driver which
+	  provides support for the RTC clock, tamper detector and 128B SRAM.
+
 config RZ_MTU3
 	tristate "Renesas RZ/G2L MTU3a core driver"
 	depends on (ARCH_RZG2L && OF) || COMPILE_TEST
diff --git a/drivers/mfd/Makefile b/drivers/mfd/Makefile
index 02b651cd7535..cd2f27492df2 100644
--- a/drivers/mfd/Makefile
+++ b/drivers/mfd/Makefile
@@ -186,6 +186,7 @@ pcf50633-objs			:= pcf50633-core.o pcf50633-irq.o
 obj-$(CONFIG_MFD_PCF50633)	+= pcf50633.o
 obj-$(CONFIG_PCF50633_ADC)	+= pcf50633-adc.o
 obj-$(CONFIG_PCF50633_GPIO)	+= pcf50633-gpio.o
+obj-$(CONFIG_MFD_RENESAS_VBATTB)	+= renesas-vbattb.o
 obj-$(CONFIG_RZ_MTU3)		+= rz-mtu3.o
 obj-$(CONFIG_ABX500_CORE)	+= abx500-core.o
 obj-$(CONFIG_MFD_DB8500_PRCMU)	+= db8500-prcmu.o
diff --git a/drivers/mfd/renesas-vbattb.c b/drivers/mfd/renesas-vbattb.c
new file mode 100644
index 000000000000..5d71565b8cbf
--- /dev/null
+++ b/drivers/mfd/renesas-vbattb.c
@@ -0,0 +1,78 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * VBATTB driver
+ *
+ * Copyright (C) 2024 Renesas Electronics Corp.
+ */
+
+#include <linux/mod_devicetable.h>
+#include <linux/of_platform.h>
+#include <linux/platform_device.h>
+#include <linux/pm_runtime.h>
+#include <linux/reset.h>
+
+static int vbattb_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct reset_control *rstc;
+	int ret;
+
+	rstc = devm_reset_control_array_get_exclusive(dev);
+	if (IS_ERR(rstc))
+		return PTR_ERR(rstc);
+
+	ret = devm_pm_runtime_enable(dev);
+	if (ret)
+		return ret;
+
+	ret = pm_runtime_resume_and_get(dev);
+	if (ret)
+		return ret;
+
+	ret = reset_control_deassert(rstc);
+	if (ret)
+		goto rpm_put;
+
+	platform_set_drvdata(pdev, rstc);
+
+	ret = devm_of_platform_populate(dev);
+	if (ret)
+		goto reset_assert;
+
+	return 0;
+
+reset_assert:
+	reset_control_assert(rstc);
+rpm_put:
+	pm_runtime_put(dev);
+	return ret;
+}
+
+static void vbattb_remove(struct platform_device *pdev)
+{
+	struct reset_control *rstc = platform_get_drvdata(pdev);
+
+	reset_control_assert(rstc);
+	pm_runtime_put(&pdev->dev);
+}
+
+static const struct of_device_id vbattb_match[] = {
+	{ .compatible = "renesas,r9a08g045-vbattb" },
+	{ /* sentinel */ },
+};
+MODULE_DEVICE_TABLE(of, vbattb_match);
+
+static struct platform_driver vbattb_driver = {
+	.probe = vbattb_probe,
+	.remove_new = vbattb_remove,
+	.driver = {
+		.name = "renesas-vbattb",
+		.of_match_table = vbattb_match,
+	},
+};
+module_platform_driver(vbattb_driver);
+
+MODULE_ALIAS("platform:renesas-vbattb");
+MODULE_AUTHOR("Claudiu Beznea <claudiu.beznea.uj at bp.renesas.com>");
+MODULE_DESCRIPTION("Renesas VBATTB driver");
+MODULE_LICENSE("GPL");
-- 
2.39.2