From 50f58c0ddada558b1552d2d2a7b74f7e037aacd7 Mon Sep 17 00:00:00 2001
From: Ciro Santilli <ciro.santilli@gmail.com>
Date: Fri, 16 Jun 2017 08:45:19 +0100
Subject: [PATCH] pci attempt. It probes!

---
 kernel_module/pci.c | 264 ++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 264 insertions(+)
 create mode 100644 kernel_module/pci.c

diff --git a/kernel_module/pci.c b/kernel_module/pci.c
new file mode 100644
index 0000000..423acd9
--- /dev/null
+++ b/kernel_module/pci.c
@@ -0,0 +1,264 @@
+/*
+http://www.zarb.org/~trem/kernel/pci/pci-driver.c
+http://nairobi-embedded.org/linux_pci_device_driver.html
+*/
+
+#include <linux/kernel.h>
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/pci.h>
+#include <linux/fs.h>
+#include <linux/cdev.h> /* cdev_ */
+#include <asm/uaccess.h> /* put_user */
+
+#define MAX_DEVICE  1
+#define DEVICE_NAME "virtual_pci"
+#define BAR_IO      2
+#define BAR_MEM     3
+
+MODULE_LICENSE("GPL");
+
+static struct pci_device_id pci_ids[] = {
+	{ PCI_DEVICE(0x1234, 0x11e8), },
+	{ 0, }
+};
+
+MODULE_DEVICE_TABLE(pci, pci_ids);
+
+static dev_t devno;
+static int major;
+
+struct pci_cdev {
+	int minor;
+	struct pci_dev *pci_dev;
+	struct cdev *cdev;
+};
+
+static struct pci_cdev pci_cdev[MAX_DEVICE];
+
+static void pci_cdev_del(struct pci_cdev pci_cdev[], int size, struct pci_dev *pdev)
+{
+	int i;
+
+	for (i=0; i<size; i++) {
+		if (pci_cdev[i].pci_dev == pdev) {
+			pci_cdev[i].pci_dev = NULL;
+		}
+	}
+}
+
+static struct pci_dev *pci_cdev_search_pci_dev(struct pci_cdev pci_cdev[], int size, int minor)
+{
+	int i;
+	struct pci_dev *pdev = NULL;
+
+	for (i=0; i<size; i++) {
+		if (pci_cdev[i].minor == minor) {
+			pdev = pci_cdev[i].pci_dev;
+			break;
+		}
+	}
+	return pdev;
+}
+
+static struct cdev *pci_cdev_search_cdev(struct pci_cdev pci_cdev[], int size, int minor)
+{
+	int i;
+	struct cdev *cdev = NULL;
+
+	for (i=0; i<size; i++) {
+		if (pci_cdev[i].minor == minor) {
+			cdev = pci_cdev[i].cdev;
+			break;
+		}
+	}
+	return cdev;
+}
+
+/**
+ * -1     => not found
+ * others => found
+ */
+static int pci_cdev_search_minor(struct pci_cdev pci_cdev[],
+		int size, struct pci_dev *pdev)
+{
+	int i, minor = -1;
+
+	for (i=0; i<size; i++) {
+		if (pci_cdev[i].pci_dev == pdev) {
+			minor = pci_cdev[i].minor;
+			break;
+		}
+	}
+	return minor;
+}
+
+static int pci_open(struct inode *inode, struct file *file)
+{
+	int minor = iminor(inode);
+	file->private_data = (void *)pci_cdev_search_pci_dev(pci_cdev, MAX_DEVICE, minor);
+	return 0;
+}
+
+static ssize_t pci_read(struct file *file,
+			char *buffer,
+			size_t length,
+			loff_t * offset)
+{
+	int byte_read = 0;
+	unsigned char value;
+	struct pci_dev *pdev = (struct pci_dev *)file->private_data;
+	unsigned long pci_io_addr = 0;
+
+	pci_io_addr = pci_resource_start(pdev,BAR_IO);
+	while (byte_read < length) {
+		value = inb(pci_io_addr + 1);
+		put_user(value, &buffer[byte_read]);
+		byte_read++;
+	}
+	return byte_read;
+}
+
+static ssize_t pci_write(struct file *filp, const char *buffer, size_t len, loff_t * off) {
+	int i;
+	unsigned char value;
+	struct pci_dev *pdev = (struct pci_dev *)filp->private_data;
+	unsigned long pci_io_addr = 0;
+
+	pci_io_addr = pci_resource_start(pdev,BAR_IO);
+	for (i=0; i<len; i++) {
+		value = (unsigned char)buffer[i];
+		outb(pci_io_addr+2, value);
+	}
+	return len;
+}
+
+static struct file_operations pci_ops = {
+	.owner   = THIS_MODULE,
+	.read    = pci_read,
+	.write   = pci_write,
+	.open    = pci_open,
+};
+
+/**
+ * 0 => this driver doesn't handle this device
+ * 1 => this driver handles this device
+ */
+static int pci_probe(struct pci_dev *dev, const struct pci_device_id *id)
+{
+	int i, ret, minor;
+	struct cdev *cdev;
+	dev_t devno;
+
+	pr_info("pci_probe\n");
+
+	ret = -1;
+	for (i=0; i<MAX_DEVICE; i++) {
+		if (pci_cdev[i].pci_dev == NULL) {
+			pci_cdev[i].pci_dev = dev;
+			minor = pci_cdev[i].minor;
+			break;
+		}
+	}
+	if (ret < 0) {
+		dev_info(&(dev->dev), "error pci_cdev_add");
+		goto error;
+	}
+
+	devno = MKDEV(major, minor);
+	cdev = cdev_alloc();
+	cdev_init(cdev, &pci_ops);
+	cdev->owner = THIS_MODULE;
+
+	/* register cdev */
+	ret = cdev_add(cdev, devno, 1);
+	if (ret < 0) {
+		dev_err(&(dev->dev), "Can't register character device\n");
+		goto error;
+	}
+	pci_cdev[minor].cdev = cdev;
+
+	dev_info(&(dev->dev), "%s The major device number is %d (%d).\n",
+	       "Registeration is a success", MAJOR(devno), MINOR(devno));
+	dev_info(&(dev->dev), "If you want to talk to the device driver,\n");
+	dev_info(&(dev->dev), "you'll have to create a device file. \n");
+	dev_info(&(dev->dev), "We suggest you use:\n");
+	dev_info(&(dev->dev), "mknod %s c %d %d\n", DEVICE_NAME, MAJOR(devno), MINOR(devno));
+	dev_info(&(dev->dev), "The device file name is important, because\n");
+	dev_info(&(dev->dev), "the ioctl program assumes that's the\n");
+	dev_info(&(dev->dev), "file you'll use.\n");
+
+	/* enable the device */
+	pci_enable_device(dev);
+
+	/* 'alloc' IO to talk with the card */
+	if (pci_request_region(dev, BAR_IO, "IO-pci") == 0) {
+		dev_err(&(dev->dev), "Can't request BAR2\n");
+		cdev_del(cdev);
+		goto error;
+	}
+
+	/* check that BAR_IO is *really* IO region */
+	if ((pci_resource_flags(dev, BAR_IO) & IORESOURCE_IO) != IORESOURCE_IO) {
+		dev_err(&(dev->dev), "BAR2 isn't an IO region\n");
+		cdev_del(cdev);
+		goto error;
+	}
+
+	return 1;
+
+error:
+	return 0;
+}
+
+static void pci_remove(struct pci_dev *dev)
+{
+	int minor;
+	struct cdev *cdev;
+
+	minor = pci_cdev_search_minor(pci_cdev, MAX_DEVICE, dev);
+	cdev = pci_cdev_search_cdev(pci_cdev, MAX_DEVICE, minor);
+	if (cdev != NULL)
+		cdev_del(cdev);
+	pci_cdev_del(pci_cdev, MAX_DEVICE, dev);
+	pci_release_region(dev, BAR_IO);
+}
+
+static struct pci_driver pci_driver = {
+	.name     = "pci",
+	.id_table = pci_ids,
+	.probe    = pci_probe,
+	.remove   = pci_remove,
+};
+
+static int __init pci_init_module(void)
+{
+	int i, first_minor, ret;
+
+	ret = alloc_chrdev_region(&devno, 0, MAX_DEVICE, "buffer");
+	major = MAJOR(devno);
+	first_minor = MINOR(devno);
+	for (i=0; i < MAX_DEVICE; i++) {
+		pci_cdev[i].minor   = first_minor++;
+		pci_cdev[i].pci_dev = NULL;
+		pci_cdev[i].cdev    = NULL;
+	}
+	ret = pci_register_driver(&pci_driver);
+	return 0;
+}
+
+static void pci_exit_module(void)
+{
+	int i;
+
+	pci_unregister_driver(&pci_driver);
+	for(i=0; i< MAX_DEVICE; i++) {
+		if (pci_cdev[i].pci_dev != NULL) {
+			cdev_del(pci_cdev[i].cdev);
+		}
+	}
+	unregister_chrdev_region(devno, MAX_DEVICE);
+}
+
+module_init(pci_init_module);
+module_exit(pci_exit_module);