patch-2.2.18 linux/drivers/char/i810_rng.c

• Lines: 490
• Date: Tue Nov 28 22:22:24 2000
• Orig file: v2.2.17/drivers/char/i810_rng.c
• Orig date: Thu Jan 1 01:00:00 1970

diff -u --new-file --recursive --exclude-from /usr/src/exclude v2.2.17/drivers/char/i810_rng.c linux/drivers/char/i810_rng.c
@@ -0,0 +1,489 @@
+/*
+
+	Hardware driver for Intel i810 Random Number Generator (RNG)
+	Copyright 2000 Jeff Garzik <jgarzik@mandrakesoft.com>
+
+	Driver Web site:  http://gtf.org/garzik/drivers/i810_rng/
+
+
+
+	Based on:
+	Intel 82802AB/82802AC Firmware Hub (FWH) Datasheet
+		May 1999 Order Number: 290658-002 R
+
+	Intel 82802 Firmware Hub: Random Number Generator
+	Programmer's Reference Manual
+		December 1999 Order Number: 298029-001 R
+
+	Intel 82802 Firmware HUB Random Number Generator Driver
+	Copyright (c) 2000 Matt Sottek <msottek@quiknet.com>
+
+	Special thanks to Matt Sottek.  I did the "guts", he
+	did the "brains" and all the testing.  (Anybody wanna send
+	me an i810 or i820?)
+
+	----------------------------------------------------------
+
+	This software may be used and distributed according to the terms
+        of the GNU Public License, incorporated herein by reference.
+
+	----------------------------------------------------------
+
+	From the firmware hub datasheet:
+
+	The Firmware Hub integrates a Random Number Generator (RNG)
+	using thermal noise generated from inherently random quantum
+	mechanical properties of silicon. When not generating new random
+	bits the RNG circuitry will enter a low power state. Intel will
+	provide a binary software driver to give third party software
+	access to our RNG for use as a security feature. At this time,
+	the RNG is only to be used with a system in an OS-present state.
+
+	----------------------------------------------------------
+
+	Theory of operation:
+
+	Character driver.  Using the standard open()
+	and read() system calls, you can read random data from
+	the i810 RNG device.  This data is NOT CHECKED by any
+	fitness tests, and could potentially be bogus (if the
+	hardware is faulty or has been tampered with).
+
+	/dev/intel_rng is char device major 10, minor 183.
+
+
+	----------------------------------------------------------
+
+	Driver notes:
+
+	* In order to unload the i810_rng module, you must first
+	make sure all users of the character device have closed
+
+	* FIXME:  Currently only one open() of the character device is allowed.
+	If another user tries to open() the device, they will get an
+	-EBUSY error.  Instead, this really should either support
+	multiple simultaneous users of the character device (not hard),
+	or simply block open() until the current user of the chrdev
+	calls close().
+
+	* FIXME: support poll()
+
+	* FIXME: should we be crazy and support mmap()?
+
+	----------------------------------------------------------
+
+ */
+
+
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <linux/fs.h>
+#include <linux/init.h>
+#include <linux/pci.h>
+#include <asm/spinlock.h>
+#include <linux/random.h>
+#include <linux/sysctl.h>
+#include <linux/miscdevice.h>
+#include <linux/mm.h>
+
+#include <asm/io.h>
+#include <asm/uaccess.h>
+
+
+/*
+ * core module and version information
+ */
+#define RNG_VERSION "0.6.2-2.2.x"
+#define RNG_MODULE_NAME "i810_rng"
+#define RNG_DRIVER_NAME   RNG_MODULE_NAME " hardware driver " RNG_VERSION
+#define PFX RNG_MODULE_NAME ": "
+
+
+/*
+ * debugging macros
+ */
+#undef RNG_DEBUG /* define to 1 to enable copious debugging info */
+
+#ifdef RNG_DEBUG
+/* note: prints function name for you */
+#define DPRINTK(fmt, args...) printk(KERN_DEBUG "%s: " fmt, __FUNCTION__ , ## args)
+#else
+#define DPRINTK(fmt, args...)
+#endif
+
+#define RNG_NDEBUG 0        /* define to 1 to disable lightweight runtime checks */
+#if RNG_NDEBUG
+#define assert(expr)
+#else
+#define assert(expr) \
+        if(!(expr)) {                                   \
+        printk( "Assertion failed! %s,%s,%s,line=%d\n", \
+        #expr,__FILE__,__FUNCTION__,__LINE__);          \
+        }
+#endif
+
+
+/*
+ * misc helper macros
+ */
+#define arraysize(x)            (sizeof(x)/sizeof(*(x)))
+
+
+/*
+ * RNG registers (offsets from rng_mem)
+ */
+#define RNG_HW_STATUS			0
+#define		RNG_PRESENT		0x40
+#define		RNG_ENABLED		0x01
+#define RNG_STATUS			1
+#define		RNG_DATA_PRESENT	0x01
+#define RNG_DATA			2
+
+#define RNG_ADDR			0xFFBC015F
+#define RNG_ADDR_LEN			3
+
+#define RNG_MISCDEV_MINOR		183 /* official */
+
+
+/*
+ * various RNG status variables.  they are globals
+ * as we only support a single RNG device
+ */
+static int rng_allocated;		/* is someone using the RNG region? */
+static int rng_hw_enabled;		/* is the RNG h/w enabled? */
+static int rng_use_count;		/* number of times RNG has been enabled */
+static void *rng_mem;			/* token to our ioremap'd RNG register area */
+static spinlock_t rng_lock = SPIN_LOCK_UNLOCKED; /* hardware lock */
+static int rng_open;			/* boolean, 0 (false) if chrdev is closed, 1 (true) if open */
+
+/*
+ * inlined helper functions for accessing RNG registers
+ */
+static inline u8 rng_hwstatus (void)
+{
+	assert (rng_mem != NULL);
+	return readb (rng_mem + RNG_HW_STATUS);
+}
+
+
+static inline void rng_hwstatus_set (u8 hw_status)
+{
+	assert (rng_mem != NULL);
+	writeb (hw_status, rng_mem + RNG_HW_STATUS);
+}
+
+
+static inline int rng_data_present (void)
+{
+	assert (rng_mem != NULL);
+	assert (rng_hw_enabled == 1);
+
+	return (readb (rng_mem + RNG_STATUS) & RNG_DATA_PRESENT) ? 1 : 0;
+}
+
+
+static inline int rng_data_read (void)
+{
+	assert (rng_mem != NULL);
+	assert (rng_hw_enabled == 1);
+
+	return readb (rng_mem + RNG_DATA);
+}
+
+
+/*
+ * rng_enable - enable or disable the RNG hardware
+ */
+static int rng_enable (int enable)
+{
+	int rc = 0;
+	u8 hw_status;
+
+	DPRINTK ("ENTER\n");
+
+	spin_lock (&rng_lock);
+
+	hw_status = rng_hwstatus ();
+
+	if (enable) {
+		rng_hw_enabled = 1;
+		rng_use_count++;
+		MOD_INC_USE_COUNT;
+	} else {
+		rng_use_count--;
+		if (rng_use_count == 0)
+			rng_hw_enabled = 0;
+		MOD_DEC_USE_COUNT;
+	}
+
+	if (rng_hw_enabled && ((hw_status & RNG_ENABLED) == 0)) {
+		rng_hwstatus_set (hw_status | RNG_ENABLED);
+		printk (KERN_INFO PFX "RNG h/w enabled\n");
+	}
+
+	else if (!rng_hw_enabled && (hw_status & RNG_ENABLED)) {
+		rng_hwstatus_set (hw_status & ~RNG_ENABLED);
+		printk (KERN_INFO PFX "RNG h/w disabled\n");
+	}
+
+	spin_unlock (&rng_lock);
+
+	if ((!!enable) != (!!(rng_hwstatus () & RNG_ENABLED))) {
+		printk (KERN_ERR PFX "Unable to %sable the RNG\n",
+			enable ? "en" : "dis");
+		rc = -EIO;
+	}
+
+	DPRINTK ("EXIT, returning %d\n", rc);
+	return rc;
+}
+
+
+static int rng_dev_open (struct inode *inode, struct file *filp)
+{
+	int rc = -EINVAL;
+
+	MOD_INC_USE_COUNT;
+
+	if ((filp->f_mode & FMODE_READ) == 0)
+		goto err_out;
+	if (filp->f_mode & FMODE_WRITE)
+		goto err_out;
+
+	spin_lock (&rng_lock);
+
+	/* only allow one open of this device, exit with -EBUSY if already open */
+	/* FIXME: we should sleep on a semaphore here, unless O_NONBLOCK */
+	if (rng_open) {
+		spin_unlock (&rng_lock);
+		rc = -EBUSY;
+		goto err_out;
+	}
+
+	rng_open = 1;
+
+	spin_unlock (&rng_lock);
+
+	if (rng_enable(1) != 0) {
+		spin_lock (&rng_lock);
+		rng_open = 0;
+		spin_unlock (&rng_lock);
+		rc = -EIO;
+		goto err_out;
+	}
+
+	return 0;
+
+err_out:
+	MOD_DEC_USE_COUNT;
+	return rc;
+}
+
+
+static int rng_dev_release (struct inode *inode, struct file *filp)
+{
+
+	if (rng_enable(0) != 0)
+		return -EIO;
+
+	spin_lock (&rng_lock);
+	rng_open = 0;
+	spin_unlock (&rng_lock);
+
+	MOD_DEC_USE_COUNT;
+	return 0;
+}
+
+
+static ssize_t rng_dev_read (struct file *filp, char * buf, size_t size,
+			     loff_t *offp)
+{
+	int have_data, copied = 0;
+	u8 data=0;
+	u8 *page;
+
+	if (size < 1)
+		return 0;
+
+	page = (unsigned char *) get_free_page (GFP_KERNEL);
+	if (!page)
+		return -ENOMEM;
+
+read_loop:
+	/* using the fact that read() can return >0 but
+	 * less than the requested amount, we simply
+	 * read up to PAGE_SIZE or buffer size, whichever
+	 * is smaller, and return that data.
+	 */
+	if ((copied == size) || (copied == PAGE_SIZE)) {
+		size_t tmpsize = (copied == size) ? size : PAGE_SIZE;
+		int rc = copy_to_user (buf, page, tmpsize);
+		free_page ((long)page);
+		if (rc) return rc;
+		return tmpsize;
+	}
+
+	spin_lock (&rng_lock);
+
+	have_data = 0;
+	if (rng_data_present ()) {
+		data = rng_data_read ();
+		have_data = 1;
+	}
+
+	spin_unlock (&rng_lock);
+
+	if (have_data) {
+		page[copied] = data;
+		copied++;
+	} else {
+		if (filp->f_flags & O_NONBLOCK) {
+			free_page ((long)page);
+			return -EAGAIN;
+		}
+	}
+
+	if (current->need_resched)
+		schedule ();
+
+	if (signal_pending (current)) {
+		free_page ((long)page);
+		return -ERESTARTSYS;
+	}
+
+	goto read_loop;
+}
+
+
+/*
+ * rng_init_one - look for and attempt to init a single RNG
+ */
+static int __init rng_init_one (struct pci_dev *dev)
+{
+	int rc;
+	u8 hw_status;
+
+	DPRINTK ("ENTER\n");
+
+	if (rng_allocated) {
+		printk (KERN_ERR PFX "this driver only supports one RNG\n");
+		DPRINTK ("EXIT, returning -EBUSY\n");
+		return -EBUSY;
+	}
+
+	rng_mem = ioremap (RNG_ADDR, RNG_ADDR_LEN);
+	if (rng_mem == NULL) {
+		printk (KERN_ERR PFX "cannot ioremap RNG Memory\n");
+		DPRINTK ("EXIT, returning -EBUSY\n");
+		rc = -EBUSY;
+		goto err_out;
+	}
+
+	/* Check for Intel 82802 */
+	hw_status = rng_hwstatus ();
+	if ((hw_status & RNG_PRESENT) == 0) {
+		printk (KERN_ERR PFX "RNG not detected\n");
+		DPRINTK ("EXIT, returning -ENODEV\n");
+		rc = -ENODEV;
+		goto err_out;
+	}
+
+	rng_allocated = 1;
+
+	rc = rng_enable (0);
+	if (rc) {
+		printk (KERN_ERR PFX "cannot disable RNG, aborting\n");
+		goto err_out;
+	}
+
+	DPRINTK ("EXIT, returning 0\n");
+	return 0;
+
+err_out:
+	if (rng_mem)
+		iounmap (rng_mem);
+	return rc;
+}
+
+
+/*
+ * Data for PCI driver interface
+ */
+
+MODULE_AUTHOR("Jeff Garzik, Matt Sottek");
+MODULE_DESCRIPTION("Intel i8xx chipset Random Number Generator (RNG) driver");
+
+
+static struct file_operations rng_chrdev_ops = {
+	open:		rng_dev_open,
+	release:	rng_dev_release,
+	read:		rng_dev_read,
+};
+
+
+static struct miscdevice rng_miscdev = {
+	RNG_MISCDEV_MINOR,
+	RNG_MODULE_NAME,
+	&rng_chrdev_ops,
+};
+
+
+/*
+ * rng_init - initialize RNG module
+ */
+int __init rng_init (void)
+{
+	int rc;
+	struct pci_dev *pdev;
+	
+	pdev = pci_find_device (0x8086, 0x2418, NULL);
+	if (!pdev)
+		pdev = pci_find_device (0x8086, 0x2428, NULL);
+	if (!pdev)
+		pdev = pci_find_device (0x8086, 0x1130, NULL);
+	if (!pdev)
+		return -ENODEV;
+
+	DPRINTK ("ENTER\n");
+
+	rc = rng_init_one(pdev);
+	if (rc) {
+		DPRINTK ("EXIT, returning -ENODEV\n");
+		return rc;
+	}
+
+	rc = misc_register (&rng_miscdev);
+	if (rc) {
+		if (rng_mem)
+			iounmap (rng_mem);
+		DPRINTK ("EXIT, returning %d\n", rc);
+		return rc;
+	}
+
+	printk (KERN_INFO RNG_DRIVER_NAME " loaded\n");
+
+	DPRINTK ("EXIT, returning 0\n");
+	return 0;
+}
+
+#ifdef MODULE
+
+int init_module (void) { return rng_init (); }
+
+/*
+ * rng_init - shutdown RNG module
+ */
+void cleanup_module (void)
+{
+	DPRINTK ("ENTER\n");
+	
+	iounmap (rng_mem);
+
+	rng_hwstatus_set (rng_hwstatus() & ~RNG_ENABLED);
+
+	misc_deregister (&rng_miscdev);
+
+	DPRINTK ("EXIT\n");
+}
+
+#endif /* MODULE */