soc: add microchip polarfire soc system controller

This driver provides an interface for other drivers to access the
functions of the system controller on the Microchip PolarFire SoC.

Signed-off-by: Conor Dooley <[e-mail]>
Signed-off-by: Nicolas Ferre <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]

drivers/soc/Kconfig

···
 source "drivers/soc/ixp4xx/Kconfig"
 source "drivers/soc/litex/Kconfig"
 source "drivers/soc/mediatek/Kconfig"
+source "drivers/soc/microchip/Kconfig"
 source "drivers/soc/qcom/Kconfig"
 source "drivers/soc/renesas/Kconfig"
 source "drivers/soc/rockchip/Kconfig"

drivers/soc/Makefile

···
 obj-$(CONFIG_SOC_XWAY)		+= lantiq/
 obj-$(CONFIG_LITEX_SOC_CONTROLLER) += litex/
 obj-y				+= mediatek/
+obj-y				+= microchip/
 obj-y				+= amlogic/
 obj-y				+= qcom/
 obj-y				+= renesas/

drivers/soc/microchip/Kconfig

···
+config POLARFIRE_SOC_SYS_CTRL
+	tristate "POLARFIRE_SOC_SYS_CTRL"
+	depends on POLARFIRE_SOC_MAILBOX
+	help
+	  This driver adds support for the PolarFire SoC (MPFS) system controller.
+
+	  To compile this driver as a module, choose M here. the
+	  module will be called mpfs_system_controller.
+
+	  If unsure, say N.

drivers/soc/microchip/Makefile

···
+obj-$(CONFIG_POLARFIRE_SOC_SYS_CTRL)	+= mpfs-sys-controller.o

drivers/soc/microchip/mpfs-sys-controller.c

···
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Microchip PolarFire SoC (MPFS) system controller driver
+ *
+ * Copyright (c) 2020-2021 Microchip Corporation. All rights reserved.
+ *
+ * Author: Conor Dooley <[e-mail]>
+ *
+ */
+
+#include <linux/slab.h>
+#include <linux/kref.h>
+#include <linux/module.h>
+#include <linux/interrupt.h>
+#include <linux/of_platform.h>
+#include <linux/mailbox_client.h>
+#include <linux/platform_device.h>
+#include <soc/microchip/mpfs.h>
+
+static DEFINE_MUTEX(transaction_lock);
+
+struct mpfs_sys_controller {
+	struct mbox_client client;
+	struct mbox_chan *chan;
+	struct completion c;
+	struct kref consumers;
+};
+
+int mpfs_blocking_transaction(struct mpfs_sys_controller *sys_controller, struct mpfs_mss_msg *msg)
+{
+	int ret, err;
+
+	err = mutex_lock_interruptible(&transaction_lock);
+	if (err)
+		return err;
+
+	reinit_completion(&sys_controller->c);
+
+	ret = mbox_send_message(sys_controller->chan, msg);
+	if (ret >= 0) {
+		if (wait_for_completion_timeout(&sys_controller->c, HZ)) {
+			ret = 0;
+		} else {
+			ret = -ETIMEDOUT;
+			dev_warn(sys_controller->client.dev,
+				 "MPFS sys controller transaction timeout\n");
+		}
+	} else {
+		dev_err(sys_controller->client.dev,
+			"mpfs sys controller transaction returned %d\n", ret);
+	}
+
+	mutex_unlock(&transaction_lock);
+
+	return ret;
+}
+EXPORT_SYMBOL(mpfs_blocking_transaction);
+
+static void rx_callback(struct mbox_client *client, void *msg)
+{
+	struct mpfs_sys_controller *sys_controller =
+		container_of(client, struct mpfs_sys_controller, client);
+
+	complete(&sys_controller->c);
+}
+
+static void mpfs_sys_controller_delete(struct kref *kref)
+{
+	struct mpfs_sys_controller *sys_controller = container_of(kref, struct mpfs_sys_controller,
+					       consumers);
+
+	mbox_free_channel(sys_controller->chan);
+	kfree(sys_controller);
+}
+
+void mpfs_sys_controller_put(void *data)
+{
+	struct mpfs_sys_controller *sys_controller = data;
+
+	kref_put(&sys_controller->consumers, mpfs_sys_controller_delete);
+}
+EXPORT_SYMBOL(mpfs_sys_controller_put);
+
+static struct platform_device subdevs[] = {
+	{
+		.name		= "mpfs-rng",
+		.id		= -1,
+	},
+	{
+		.name		= "mpfs-generic-service",
+		.id		= -1,
+	}
+};
+
+static int mpfs_sys_controller_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct mpfs_sys_controller *sys_controller;
+	int i;
+
+	sys_controller = devm_kzalloc(dev, sizeof(*sys_controller), GFP_KERNEL);
+	if (!sys_controller)
+		return -ENOMEM;
+
+	sys_controller->client.dev = dev;
+	sys_controller->client.rx_callback = rx_callback;
+	sys_controller->client.tx_block = 1U;
+
+	sys_controller->chan = mbox_request_channel(&sys_controller->client, 0);
+	if (IS_ERR(sys_controller->chan))
+		return dev_err_probe(dev, PTR_ERR(sys_controller->chan),
+				     "Failed to get mbox channel\n");
+
+	init_completion(&sys_controller->c);
+	kref_init(&sys_controller->consumers);
+
+	platform_set_drvdata(pdev, sys_controller);
+
+	dev_info(&pdev->dev, "Registered MPFS system controller\n");
+
+	for (i = 0; i < ARRAY_SIZE(subdevs); i++) {
+		subdevs[i].dev.parent = dev;
+		if (platform_device_register(&subdevs[i]))
+			dev_warn(dev, "Error registering sub device %s\n", subdevs[i].name);
+	}
+
+	return 0;
+}
+
+static int mpfs_sys_controller_remove(struct platform_device *pdev)
+{
+	struct mpfs_sys_controller *sys_controller = platform_get_drvdata(pdev);
+
+	mpfs_sys_controller_put(sys_controller);
+
+	return 0;
+}
+
+static const struct of_device_id mpfs_sys_controller_of_match[] = {
+	{.compatible = "microchip,mpfs-sys-controller", },
+	{},
+};
+MODULE_DEVICE_TABLE(of, mpfs_sys_controller_of_match);
+
+struct mpfs_sys_controller *mpfs_sys_controller_get(struct device *dev)
+{
+	const struct of_device_id *match;
+	struct mpfs_sys_controller *sys_controller;
+	int ret;
+
+	if (!dev->parent)
+		goto err_no_device;
+
+	match = of_match_node(mpfs_sys_controller_of_match,  dev->parent->of_node);
+	of_node_put(dev->parent->of_node);
+	if (!match)
+		goto err_no_device;
+
+	sys_controller = dev_get_drvdata(dev->parent);
+	if (!sys_controller)
+		goto err_bad_device;
+
+	if (!kref_get_unless_zero(&sys_controller->consumers))
+		goto err_bad_device;
+
+	ret = devm_add_action_or_reset(dev, mpfs_sys_controller_put, sys_controller);
+	if (ret)
+		return ERR_PTR(ret);
+
+	return sys_controller;
+
+err_no_device:
+	dev_dbg(dev, "Parent device was not an MPFS system controller\n");
+	return ERR_PTR(-ENODEV);
+
+err_bad_device:
+	dev_dbg(dev, "MPFS system controller found but could not register as a sub device\n");
+	return ERR_PTR(-EPROBE_DEFER);
+}
+EXPORT_SYMBOL(mpfs_sys_controller_get);
+
+static struct platform_driver mpfs_sys_controller_driver = {
+	.driver = {
+		.name = "mpfs-sys-controller",
+		.of_match_table = mpfs_sys_controller_of_match,
+	},
+	.probe = mpfs_sys_controller_probe,
+	.remove = mpfs_sys_controller_remove,
+};
+module_platform_driver(mpfs_sys_controller_driver);
+
+MODULE_LICENSE("GPL v2");
+MODULE_AUTHOR("Conor Dooley <[e-mail]>");
+MODULE_DESCRIPTION("MPFS system controller driver");

include/soc/microchip/mpfs.h

···
 
 #if IS_ENABLED(CONFIG_POLARFIRE_SOC_SYS_CTRL)
 
-int mpfs_blocking_transaction(struct mpfs_sys_controller *mpfs_client, void *msg);
+int mpfs_blocking_transaction(struct mpfs_sys_controller *mpfs_client, struct mpfs_mss_msg *msg);
 
-struct mpfs_sys_controller *mpfs_sys_controller_get(struct device_node *mailbox_node);
+struct mpfs_sys_controller *mpfs_sys_controller_get(struct device *dev);
 
 #endif /* if IS_ENABLED(CONFIG_POLARFIRE_SOC_SYS_CTRL) */