[PATCH v4 02/11] mfd: Add support for Kontron sl28cpld management controller

[Michael Walle <michael@walle.cc>]

Add the core support for the board management controller found on the
SMARC-sAL28 board. It consists of the following functions:
 - watchdog
 - GPIO controller
 - PWM controller
 - fan sensor
 - interrupt controller

At the moment, this controller is used on the Kontron SMARC-sAL28 board.

Please note that the MFD driver is defined as bool in the Kconfig
because the next patch will add interrupt support.

Signed-off-by: Michael Walle <michael@walle.cc>
---
 drivers/mfd/Kconfig    | 19 ++++++++++
 drivers/mfd/Makefile   |  2 ++
 drivers/mfd/sl28cpld.c | 79 ++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 100 insertions(+)
 create mode 100644 drivers/mfd/sl28cpld.c

diff --git a/drivers/mfd/Kconfig b/drivers/mfd/Kconfig
index 4f8b73d92df3..5c0cd514d197 100644
--- a/drivers/mfd/Kconfig
+++ b/drivers/mfd/Kconfig
@@ -2109,5 +2109,24 @@ config SGI_MFD_IOC3
 	  If you have an SGI Origin, Octane, or a PCI IOC3 card,
 	  then say Y. Otherwise say N.
 
+config MFD_SL28CPLD
+	bool "Kontron sl28 core driver"
+	depends on I2C=y
+	depends on OF
+	select REGMAP_I2C
+	select MFD_CORE
+	help
+	  This option enables support for the board management controller
+	  found on the Kontron sl28 CPLD. You have to select individual
+	  functions, such as watchdog, GPIO, etc, under the corresponding menus
+	  in order to enable them.
+
+	  Currently supported boards are:
+
+		Kontron SMARC-sAL28
+
+	  To compile this driver as a module, choose M here: the module will be
+	  called sl28cpld.
+
 endmenu
 endif
diff --git a/drivers/mfd/Makefile b/drivers/mfd/Makefile
index 9367a92f795a..be59fb40aa28 100644
--- a/drivers/mfd/Makefile
+++ b/drivers/mfd/Makefile
@@ -264,3 +264,5 @@ obj-$(CONFIG_MFD_ROHM_BD718XX)	+= rohm-bd718x7.o
 obj-$(CONFIG_MFD_STMFX) 	+= stmfx.o
 
 obj-$(CONFIG_SGI_MFD_IOC3)	+= ioc3.o
+
+obj-$(CONFIG_MFD_SL28CPLD)	+= sl28cpld.o
diff --git a/drivers/mfd/sl28cpld.c b/drivers/mfd/sl28cpld.c
new file mode 100644
index 000000000000..a23194bb6efa
--- /dev/null
+++ b/drivers/mfd/sl28cpld.c
@@ -0,0 +1,79 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * MFD core for the sl28cpld.
+ *
+ * Copyright 2019 Kontron Europe GmbH
+ */
+
+#include <linux/i2c.h>
+#include <linux/interrupt.h>
+#include <linux/kernel.h>
+#include <linux/mfd/core.h>
+#include <linux/module.h>
+#include <linux/of_platform.h>
+#include <linux/regmap.h>
+
+#define SL28CPLD_VERSION	0x03
+#define SL28CPLD_MIN_REQ_VERSION 14
+
+struct sl28cpld {
+	struct device *dev;
+	struct regmap *regmap;
+};
+
+static const struct regmap_config sl28cpld_regmap_config = {
+	.reg_bits = 8,
+	.val_bits = 8,
+	.reg_stride = 1,
+};
+
+static int sl28cpld_probe(struct i2c_client *i2c)
+{
+	struct sl28cpld *sl28cpld;
+	struct device *dev = &i2c->dev;
+	unsigned int cpld_version;
+	int ret;
+
+	sl28cpld = devm_kzalloc(dev, sizeof(*sl28cpld), GFP_KERNEL);
+	if (!sl28cpld)
+		return -ENOMEM;
+
+	sl28cpld->regmap = devm_regmap_init_i2c(i2c, &sl28cpld_regmap_config);
+	if (IS_ERR(sl28cpld->regmap))
+		return PTR_ERR(sl28cpld->regmap);
+
+	ret = regmap_read(sl28cpld->regmap, SL28CPLD_VERSION, &cpld_version);
+	if (ret)
+		return ret;
+
+	if (cpld_version < SL28CPLD_MIN_REQ_VERSION) {
+		dev_err(dev, "unsupported CPLD version %d\n", cpld_version);
+		return -ENODEV;
+	}
+
+	sl28cpld->dev = dev;
+	i2c_set_clientdata(i2c, sl28cpld);
+
+	dev_info(dev, "successfully probed. CPLD version %d\n", cpld_version);
+
+	return devm_of_platform_populate(&i2c->dev);
+}
+
+static const struct of_device_id sl28cpld_of_match[] = {
+	{ .compatible = "kontron,sl28cpld-r1", },
+	{}
+};
+MODULE_DEVICE_TABLE(of, sl28cpld_of_match);
+
+static struct i2c_driver sl28cpld_driver = {
+	.probe_new = sl28cpld_probe,
+	.driver = {
+		.name = "sl28cpld",
+		.of_match_table = of_match_ptr(sl28cpld_of_match),
+	},
+};
+module_i2c_driver(sl28cpld_driver);
+
+MODULE_DESCRIPTION("sl28cpld MFD Core Driver");
+MODULE_AUTHOR("Michael Walle <michael@walle.cc>");
+MODULE_LICENSE("GPL");
-- 
2.20.1