misc: xilinx-sdfec: add core driver

Implement a platform driver that matches with xlnx,
sd-fec-1.1 device tree node and registers as a character
device, including:
- SD-FEC driver binds to sdfec DT node.
- creates and initialise an initial driver dev structure.
- add the driver in Linux build and Kconfig.
Tested-by: Dragan Cvetic <dragan.cvetic@xilinx.com>
Signed-off-by: Derek Kiernan <derek.kiernan@xilinx.com>
Signed-off-by: Dragan Cvetic <dragan.cvetic@xilinx.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/misc/Kconfig

@@ -472,6 +472,18 @@ config PCI_ENDPOINT_TEST
            Enable this configuration option to enable the host side test driver
            for PCI Endpoint.
 
+config XILINX_SDFEC
+	tristate "Xilinx SDFEC 16"
+	help
+	  This option enables support for the Xilinx SDFEC (Soft Decision
+	  Forward Error Correction) driver. This enables a char driver
+	  for the SDFEC.
+
+	  You may select this driver if your design instantiates the
+	  SDFEC(16nm) hardened block. To compile this as a module choose M.
+
+	  If unsure, say N.
+
 config MISC_RTSX
 	tristate
 	default MISC_RTSX_PCI || MISC_RTSX_USB

drivers/misc/Makefile

@@ -59,3 +59,4 @@ obj-$(CONFIG_OCXL)		+= ocxl/
 obj-y				+= cardreader/
 obj-$(CONFIG_PVPANIC)   	+= pvpanic.o
 obj-$(CONFIG_HABANA_AI)		+= habanalabs/
+obj-$(CONFIG_XILINX_SDFEC)	+= xilinx_sdfec.o

drivers/misc/xilinx_sdfec.c

+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Xilinx SDFEC
+ *
+ * Copyright (C) 2019 Xilinx, Inc.
+ *
+ * Description:
+ * This driver is developed for SDFEC16 (Soft Decision FEC 16nm)
+ * IP. It exposes a char device which supports file operations
+ * like  open(), close() and ioctl().
+ */
+
+#include <linux/miscdevice.h>
+#include <linux/io.h>
+#include <linux/interrupt.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/of_platform.h>
+#include <linux/poll.h>
+#include <linux/slab.h>
+#include <linux/clk.h>
+
+#define DEV_NAME_LEN 12
+
+static struct idr dev_idr;
+static struct mutex dev_idr_lock;
+
+/**
+ * struct xsdfec_dev - Driver data for SDFEC
+ * @regs: device physical base address
+ * @dev: pointer to device struct
+ * @miscdev: Misc device handle
+ * @error_data_lock: Error counter and states spinlock
+ * @dev_name: Device name
+ * @dev_id: Device ID
+ *
+ * This structure contains necessary state for SDFEC driver to operate
+ */
+struct xsdfec_dev {
+	void __iomem *regs;
+	struct device *dev;
+	struct miscdevice miscdev;
+	/* Spinlock to protect state_updated and stats_updated */
+	spinlock_t error_data_lock;
+	char dev_name[DEV_NAME_LEN];
+	int dev_id;
+};
+
+static const struct file_operations xsdfec_fops = {
+	.owner = THIS_MODULE,
+};
+
+static void xsdfec_idr_remove(struct xsdfec_dev *xsdfec)
+{
+	mutex_lock(&dev_idr_lock);
+	idr_remove(&dev_idr, xsdfec->dev_id);
+	mutex_unlock(&dev_idr_lock);
+}
+
+static int xsdfec_probe(struct platform_device *pdev)
+{
+	struct xsdfec_dev *xsdfec;
+	struct device *dev;
+	struct resource *res;
+	int err;
+
+	xsdfec = devm_kzalloc(&pdev->dev, sizeof(*xsdfec), GFP_KERNEL);
+	if (!xsdfec)
+		return -ENOMEM;
+
+	xsdfec->dev = &pdev->dev;
+	spin_lock_init(&xsdfec->error_data_lock);
+
+	dev = xsdfec->dev;
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	xsdfec->regs = devm_ioremap_resource(dev, res);
+	if (IS_ERR(xsdfec->regs)) {
+		err = PTR_ERR(xsdfec->regs);
+		return err;
+	}
+
+	/* Save driver private data */
+	platform_set_drvdata(pdev, xsdfec);
+
+	mutex_lock(&dev_idr_lock);
+	err = idr_alloc(&dev_idr, xsdfec->dev_name, 0, 0, GFP_KERNEL);
+	mutex_unlock(&dev_idr_lock);
+	if (err < 0)
+		goto err_xsddev_idr;
+	xsdfec->dev_id = err;
+
+	snprintf(xsdfec->dev_name, DEV_NAME_LEN, "xsdfec%d", xsdfec->dev_id);
+	xsdfec->miscdev.minor = MISC_DYNAMIC_MINOR;
+	xsdfec->miscdev.name = xsdfec->dev_name;
+	xsdfec->miscdev.fops = &xsdfec_fops;
+	xsdfec->miscdev.parent = dev;
+	err = misc_register(&xsdfec->miscdev);
+	if (err) {
+		dev_err(dev, "error:%d. Unable to register device", err);
+		return err;
+	}
+	return 0;
+
+err_xsddev_idr:
+	xsdfec_idr_remove(xsdfec);
+
+	return err;
+}
+
+static int xsdfec_remove(struct platform_device *pdev)
+{
+	struct xsdfec_dev *xsdfec;
+
+	xsdfec = platform_get_drvdata(pdev);
+	misc_deregister(&xsdfec->miscdev);
+	xsdfec_idr_remove(xsdfec);
+	return 0;
+}
+
+static const struct of_device_id xsdfec_of_match[] = {
+	{
+		.compatible = "xlnx,sd-fec-1.1",
+	},
+	{ /* end of table */ }
+};
+MODULE_DEVICE_TABLE(of, xsdfec_of_match);
+
+static struct platform_driver xsdfec_driver = {
+	.driver = {
+		.name = "xilinx-sdfec",
+		.of_match_table = xsdfec_of_match,
+	},
+	.probe = xsdfec_probe,
+	.remove =  xsdfec_remove,
+};
+
+static int __init xsdfec_init(void)
+{
+	int err;
+
+	mutex_init(&dev_idr_lock);
+	idr_init(&dev_idr);
+	err = platform_driver_register(&xsdfec_driver);
+	if (err < 0) {
+		pr_err("%s Unabled to register SDFEC driver", __func__);
+		return err;
+	}
+	return 0;
+}
+
+static void __exit xsdfec_exit(void)
+{
+	platform_driver_unregister(&xsdfec_driver);
+	idr_destroy(&dev_idr);
+}
+
+module_init(xsdfec_init);
+module_exit(xsdfec_exit);
+
+MODULE_AUTHOR("Xilinx, Inc");
+MODULE_DESCRIPTION("Xilinx SD-FEC16 Driver");
+MODULE_LICENSE("GPL");