[pddd]: Adding support for I2CFPGA in PDDF (#13475)

Why I did it
Some of the platform vendors use FPGA in the HW design. This FPGA is connected to the CPU via I2C bus. Adding a common module and a driver to be used for such FPGA in PDDF.

How I did it
Added 'pddf_fpgai2c_module' and 'pddf_fpgai2c_driver' kernel modules which takes the platform dependent data from PDDF JSON files and creates an I2C client for the FPGA.

How to verify it
Any platform having such an FPGA and brought up using PDDF would use these kernel modules. The detail representation of such a device in PDDF JSON file is covered in the HLD.

platform/pddf/i2c/debian/rules

@@ -18,7 +18,7 @@ PACKAGE_PRE_NAME := sonic-platform-pddf
 KVERSION   ?= $(shell uname -r)
 KERNEL_SRC :=  /lib/modules/$(KVERSION)
 MOD_SRC_DIR:= $(shell pwd)
-MODULE_DIRS:= client cpld cpld/driver cpldmux cpldmux/driver fan fan/driver mux gpio led psu psu/driver sysstatus xcvr xcvr/driver
+MODULE_DIRS:= client cpld cpld/driver cpldmux cpldmux/driver fpgai2c fpgai2c/driver fan fan/driver mux gpio led psu psu/driver sysstatus xcvr xcvr/driver
 MODULE_DIR:= modules
 UTILS_DIR := utils
 SERVICE_DIR := service

platform/pddf/i2c/modules/Makefile

@@ -1 +1 @@
-obj-m := client/ cpld/ cpldmux/ xcvr/ mux/ gpio/ psu/ fan/ led/ sysstatus/
+obj-m := client/ cpld/ cpldmux/ fpgai2c/ xcvr/ mux/ gpio/ psu/ fan/ led/ sysstatus/

platform/pddf/i2c/modules/fpgai2c/Makefile

@@ -0,0 +1,4 @@
+obj-m := driver/
+obj-m += pddf_fpgai2c_module.o
+
+ccflags-y:= -I$(M)/modules/include

platform/pddf/i2c/modules/fpgai2c/driver/Makefile

@@ -0,0 +1,5 @@
+TARGET = pddf_fpgai2c_driver
+
+obj-m := $(TARGET).o
+
+ccflags-y := -I$(M)/modules/include

platform/pddf/i2c/modules/fpgai2c/driver/pddf_fpgai2c_driver.c

@@ -0,0 +1,228 @@
+/*
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * Description:
+ *   A pddf kernel driver module for FPGA connected to the CPU by I2C bus
+ */
+
+#include <linux/module.h>
+#include <linux/i2c.h>
+#include <linux/slab.h>
+#include <linux/list.h>
+#include <linux/dmi.h>
+#include "pddf_fpgai2c_defs.h"
+
+extern PDDF_FPGAI2C_DATA pddf_fpgai2c_data;
+
+
+static LIST_HEAD(fpgai2c_client_list);
+static struct mutex	list_lock;
+
+struct fpgai2c_client_node {
+	struct i2c_client *client;
+	struct list_head   list;
+};
+
+int board_i2c_fpga_read(unsigned short fpga_addr, u8 reg)
+{
+	struct list_head   *list_node = NULL;
+	struct fpgai2c_client_node *fpga_node = NULL;
+	int ret = -EPERM;
+
+
+	mutex_lock(&list_lock);
+
+	list_for_each(list_node, &fpgai2c_client_list)
+	{
+		fpga_node = list_entry(list_node, struct fpgai2c_client_node, list);
+
+		if (fpga_node->client->addr == fpga_addr) {
+			ret = i2c_smbus_read_byte_data(fpga_node->client, reg);
+			break;
+		}
+	}
+
+	mutex_unlock(&list_lock);
+
+	return ret;
+}
+EXPORT_SYMBOL(board_i2c_fpga_read);
+
+int board_i2c_fpga_write(unsigned short fpga_addr, u8 reg, u8 value)
+{
+	struct list_head   *list_node = NULL;
+	struct fpgai2c_client_node *fpga_node = NULL;
+	int ret = -EIO;
+
+
+	mutex_lock(&list_lock);
+
+	list_for_each(list_node, &fpgai2c_client_list)
+	{
+		fpga_node = list_entry(list_node, struct fpgai2c_client_node, list);
+
+		if (fpga_node->client->addr == fpga_addr) {
+			ret = i2c_smbus_write_byte_data(fpga_node->client, reg, value);
+			break;
+		}
+	}
+
+	mutex_unlock(&list_lock);
+
+	return ret;
+}
+EXPORT_SYMBOL(board_i2c_fpga_write);
+
+ssize_t regval_show(struct device *dev, struct device_attribute *attr, char *buf)
+{
+    int len = 0;
+    struct i2c_client *client = to_i2c_client(dev);
+
+    mutex_lock(&pddf_fpgai2c_data.fpga_lock);
+    // Put code here to read the register value and print it
+    if (pddf_fpgai2c_data.reg_addr!=0)
+        len = sprintf(buf, "0x%2.2x\n", board_i2c_fpga_read(client->addr, pddf_fpgai2c_data.reg_addr));
+    else
+        len = sprintf(buf, "xx\n");
+
+    mutex_unlock(&pddf_fpgai2c_data.fpga_lock);
+    return len;
+}
+
+static DEVICE_ATTR_RO(regval);
+
+static struct attribute *fpgai2c_attrs[] = {
+    &dev_attr_regval.attr,
+    NULL,
+};
+
+static struct attribute_group fpgai2c_attribute_group = {
+    .attrs = fpgai2c_attrs,
+};
+
+
+
+
+/* Addresses scanned for board_i2c_fpga
+ */
+static const unsigned short normal_i2c[] = { I2C_CLIENT_END };
+
+static void board_i2c_fpga_add_client(struct i2c_client *client)
+{
+	struct fpgai2c_client_node *node = kzalloc(sizeof(struct fpgai2c_client_node), GFP_KERNEL);
+
+	if (!node) {
+		dev_dbg(&client->dev, "Can't allocate fpgai2c_client_node (0x%x)\n", client->addr);
+		return;
+	}
+
+	node->client = client;
+
+	mutex_lock(&list_lock);
+	list_add(&node->list, &fpgai2c_client_list);
+	mutex_unlock(&list_lock);
+}
+
+static void board_i2c_fpga_remove_client(struct i2c_client *client)
+{
+	struct list_head		*list_node = NULL;
+	struct fpgai2c_client_node *fpga_node = NULL;
+	int found = 0;
+
+	mutex_lock(&list_lock);
+
+	list_for_each(list_node, &fpgai2c_client_list)
+	{
+		fpga_node = list_entry(list_node, struct fpgai2c_client_node, list);
+
+		if (fpga_node->client == client) {
+			found = 1;
+			break;
+		}
+	}
+
+	if (found) {
+		list_del(list_node);
+		kfree(fpga_node);
+	}
+
+	mutex_unlock(&list_lock);
+}
+
+static int board_i2c_fpga_probe(struct i2c_client *client,
+			const struct i2c_device_id *dev_id)
+{
+	int status;
+
+	if (!i2c_check_functionality(client->adapter, I2C_FUNC_SMBUS_BYTE_DATA)) {
+		dev_dbg(&client->dev, "i2c_check_functionality failed (0x%x)\n", client->addr);
+		status = -EIO;
+		goto exit;
+	}
+
+    /* Register sysfs hooks */
+    status = sysfs_create_group(&client->dev.kobj, &fpgai2c_attribute_group);
+    if (status) {
+        goto exit;
+    }
+
+	dev_dbg(&client->dev, "chip found\n");
+	board_i2c_fpga_add_client(client);
+
+	return 0;
+
+exit:
+	return status;
+}
+
+static int board_i2c_fpga_remove(struct i2c_client *client)
+{
+    sysfs_remove_group(&client->dev.kobj, &fpgai2c_attribute_group);
+	board_i2c_fpga_remove_client(client);
+
+	return 0;
+}
+
+static const struct i2c_device_id board_i2c_fpga_id[] = {
+	{ "i2c_fpga", 0 },
+	{}
+};
+MODULE_DEVICE_TABLE(i2c, board_i2c_fpga_id);
+
+static struct i2c_driver board_i2c_fpga_driver = {
+	.class		= I2C_CLASS_HWMON,
+	.driver = {
+		.name = "i2c_fpga",
+	},
+	.probe		= board_i2c_fpga_probe,
+	.remove	   	= board_i2c_fpga_remove,
+	.id_table	= board_i2c_fpga_id,
+	.address_list = normal_i2c,
+};
+
+static int __init board_i2c_fpga_init(void)
+{
+	mutex_init(&list_lock);
+	return i2c_add_driver(&board_i2c_fpga_driver);
+}
+
+static void __exit board_i2c_fpga_exit(void)
+{
+	i2c_del_driver(&board_i2c_fpga_driver);
+}
+
+MODULE_AUTHOR("Broadcom");
+MODULE_DESCRIPTION("board_i2c_fpga driver");
+MODULE_LICENSE("GPL");
+
+module_init(board_i2c_fpga_init);
+module_exit(board_i2c_fpga_exit);