PATCH: 2.5 Forward port AMD random number generator

[Alan Cox]

diff -u --new-file --recursive --exclude-from /usr/src/exclude linux.2.5.40/drivers/char/amd768_rng.c linux.2.5.40-ac1/drivers/char/amd768_rng.c
--- linux.2.5.40/drivers/char/amd768_rng.c	1970-01-01 01:00:00.000000000 +0100
+++ linux.2.5.40-ac1/drivers/char/amd768_rng.c	2002-10-02 22:29:55.000000000 +0100
@@ -0,0 +1,295 @@
+/*
+ 	Hardware driver for the AMD 768 Random Number Generator (RNG)
+	(c) Copyright 2001 Red Hat Inc <[e-mail]>
+ 
+ 	derived from
+ 
+	Hardware driver for Intel i810 Random Number Generator (RNG)
+	Copyright 2000,2001 Jeff Garzik <[e-mail]>
+	Copyright 2000,2001 Philipp Rumpf <[e-mail]>
+
+	Please read Documentation/i810_rng.txt for details on use.
+
+	----------------------------------------------------------
+	This software may be used and distributed according to the terms
+        of the GNU General Public License, incorporated herein by reference.
+
+ */
+
+
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <linux/fs.h>
+#include <linux/init.h>
+#include <linux/pci.h>
+#include <linux/interrupt.h>
+#include <linux/spinlock.h>
+#include <linux/random.h>
+#include <linux/miscdevice.h>
+#include <linux/smp_lock.h>
+#include <linux/mm.h>
+#include <linux/delay.h>
+
+#include <asm/io.h>
+#include <asm/uaccess.h>
+
+
+/*
+ * core module and version information
+ */
+#define RNG_VERSION "0.1.0"
+#define RNG_MODULE_NAME "amd768_rng"
+#define RNG_DRIVER_NAME   RNG_MODULE_NAME " hardware driver " RNG_VERSION
+#define PFX RNG_MODULE_NAME ": "
+
+
+/*
+ * debugging macros
+ */
+#undef RNG_DEBUG /* define 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
+
+#undef RNG_NDEBUG        /* define to disable lightweight runtime checks */
+#ifdef 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
+
+#define RNG_MISCDEV_MINOR		183 /* official */
+
+/*
+ * various RNG status variables.  they are globals
+ * as we only support a single RNG device
+ */
+
+static u32 pmbase;			/* PMxx I/O base */
+static struct semaphore rng_open_sem;	/* Semaphore for serializing rng_open/release */
+
+
+/*
+ * inlined helper functions for accessing RNG registers
+ */
+
+static inline int rng_data_present (void)
+{
+      	return inl(pmbase+0xF4) & 1;
+}
+
+
+static inline int rng_data_read (void)
+{
+	return inl(pmbase+0xF0);
+}
+
+static int rng_dev_open (struct inode *inode, struct file *filp)
+{
+	if ((filp->f_mode & FMODE_READ) == 0)
+		return -EINVAL;
+	if (filp->f_mode & FMODE_WRITE)
+		return -EINVAL;
+
+	/* wait for device to become free */
+	if (filp->f_flags & O_NONBLOCK) {
+		if (down_trylock (&rng_open_sem))
+			return -EAGAIN;
+	} else {
+		if (down_interruptible (&rng_open_sem))
+			return -ERESTARTSYS;
+	}
+	return 0;
+}
+
+
+static int rng_dev_release (struct inode *inode, struct file *filp)
+{
+	up(&rng_open_sem);
+	return 0;
+}
+
+
+static ssize_t rng_dev_read (struct file *filp, char *buf, size_t size,
+			     loff_t * offp)
+{
+	static spinlock_t rng_lock = SPIN_LOCK_UNLOCKED;
+	int have_data;
+	u32 data = 0;
+	ssize_t ret = 0;
+
+	while (size) {
+		spin_lock(&rng_lock);
+
+		have_data = 0;
+		if (rng_data_present()) {
+			data = rng_data_read();
+			have_data = 4;
+		}
+
+		spin_unlock (&rng_lock);
+
+		while (have_data > 0) {
+			if (put_user((u8)data, buf++)) {
+				ret = ret ? : -EFAULT;
+				break;
+			}
+			size--;
+			ret++;
+			have_data--;
+			data>>=8;
+		}
+
+		if (filp->f_flags & O_NONBLOCK)
+			return ret ? : -EAGAIN;
+
+		if(need_resched())
+		{
+			current->state = TASK_INTERRUPTIBLE;
+			schedule_timeout(1);
+		}
+		else
+			udelay(200);	/* FIXME: We could poll for 250uS ?? */
+
+		if (signal_pending (current))
+			return ret ? : -ERESTARTSYS;
+	}
+	return ret;
+}
+
+
+static struct file_operations rng_chrdev_ops = {
+	owner:		THIS_MODULE,
+	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_one - look for and attempt to init a single RNG
+ */
+static int __init rng_init_one (struct pci_dev *dev)
+{
+	int rc;
+	u8 rnen;
+
+	DPRINTK ("ENTER\n");
+
+	rc = misc_register (&rng_miscdev);
+	if (rc) {
+		printk (KERN_ERR PFX "cannot register misc device\n");
+		DPRINTK ("EXIT, returning %d\n", rc);
+		goto err_out;
+	}
+
+	pci_read_config_dword(dev, 0x58, &pmbase);
+
+	pmbase&=0x0000FF00;
+
+	if(pmbase == 0)
+	{
+		printk (KERN_ERR PFX "power management base not set\n");
+		DPRINTK ("EXIT, returning %d\n", rc);
+		goto err_out_free_miscdev;
+	}
+
+	pci_read_config_byte(dev, 0x40, &rnen);
+	rnen|=(1<<7);	/* RNG on */
+	pci_write_config_byte(dev, 0x40, rnen);
+
+	pci_read_config_byte(dev, 0x41, &rnen);
+	rnen|=(1<<7);	/* PMIO enable */
+	pci_write_config_byte(dev, 0x41, rnen);
+
+	printk(KERN_INFO PFX "AMD768 system management I/O registers at 0x%X.\n", pmbase);
+	DPRINTK ("EXIT, returning 0\n");
+	return 0;
+
+err_out_free_miscdev:
+	misc_deregister (&rng_miscdev);
+err_out:
+	return rc;
+}
+
+
+/*
+ * Data for PCI driver interface
+ *
+ * This data only exists for exporting the supported
+ * PCI ids via MODULE_DEVICE_TABLE.  We do not actually
+ * register a pci_driver, because someone else might one day
+ * want to register another driver on the same PCI id.
+ */
+static struct pci_device_id rng_pci_tbl[] __initdata = {
+	{ 0x1022, 0x7443, PCI_ANY_ID, PCI_ANY_ID, },
+	{ 0, },
+};
+MODULE_DEVICE_TABLE (pci, rng_pci_tbl);
+
+
+MODULE_AUTHOR("Alan Cox, Jeff Garzik, Philipp Rumpf, Matt Sottek");
+MODULE_DESCRIPTION("AMD 768 Random Number Generator (RNG) driver");
+MODULE_LICENSE("GPL");
+
+
+/*
+ * rng_init - initialize RNG module
+ */
+static int __init rng_init (void)
+{
+	int rc;
+	struct pci_dev *pdev;
+
+	DPRINTK ("ENTER\n");
+
+	init_MUTEX (&rng_open_sem);
+
+	pci_for_each_dev(pdev) {
+		if (pci_match_device (rng_pci_tbl, pdev) != NULL)
+			goto match;
+	}
+
+	DPRINTK ("EXIT, returning -ENODEV\n");
+	return -ENODEV;
+
+match:
+	rc = rng_init_one (pdev);
+	if (rc)
+		return rc;
+
+	printk (KERN_INFO RNG_DRIVER_NAME " loaded\n");
+
+	DPRINTK ("EXIT, returning 0\n");
+	return 0;
+}
+
+
+/*
+ * rng_init - shutdown RNG module
+ */
+static void __exit rng_cleanup (void)
+{
+	DPRINTK ("ENTER\n");
+	misc_deregister (&rng_miscdev);
+	DPRINTK ("EXIT\n");
+}
+
+
+module_init (rng_init);
+module_exit (rng_cleanup);
diff -u --new-file --recursive --exclude-from /usr/src/exclude linux.2.5.40/drivers/char/Config.help linux.2.5.40-ac1/drivers/char/Config.help
--- linux.2.5.40/drivers/char/Config.help	2002-10-02 21:33:46.000000000 +0100
+++ linux.2.5.40-ac1/drivers/char/Config.help	2002-10-02 22:22:38.000000000 +0100
@@ -648,6 +648,21 @@
 
   If unsure, say N.
 
+CONFIG_AMD_RNG
+  This driver provides kernel-side support for the Random Number
+  Generator hardware found on AMD 76x based motherboards.
+
+  Both a character driver, used to read() entropy data, and a timer
+  function which automatically adds entropy directly into the
+  kernel pool, are exported by this driver.
+
+  To compile this driver as a module ( = code which can be inserted in
+  and removed from the running kernel whenever you want), say M here
+  and read <file:Documentation/modules.txt>. The module will be called
+  i810_rng.o.
+
+  If unsure, say N.
+
 CONFIG_WATCHDOG
   If you say Y here (and to one of the following options) and create a
   character special file /dev/watchdog with major number 10 and minor
diff -u --new-file --recursive --exclude-from /usr/src/exclude linux.2.5.40/drivers/char/Config.in linux.2.5.40-ac1/drivers/char/Config.in
--- linux.2.5.40/drivers/char/Config.in	2002-10-02 21:33:46.000000000 +0100
+++ linux.2.5.40-ac1/drivers/char/Config.in	2002-10-02 22:21:19.000000000 +0100
@@ -149,6 +149,9 @@
 if [ "$CONFIG_X86" = "y" -o "$CONFIG_IA64" = "y" ]; then
    dep_tristate 'Intel i8x0 Random Number Generator support' CONFIG_INTEL_RNG $CONFIG_PCI
 fi
+if [ "$CONFIG_X86" = "y" ]; then
+   dep_tristate 'AMD 768 Random Number Generator support' CONFIG_AMD_RNG $CONFIG_PCI
+fi
 tristate '/dev/nvram support' CONFIG_NVRAM
 tristate 'Enhanced Real Time Clock Support' CONFIG_RTC
 if [ "$CONFIG_RTC" != "y" ]; then
diff -u --new-file --recursive --exclude-from /usr/src/exclude linux.2.5.40/drivers/char/Makefile linux.2.5.40-ac1/drivers/char/Makefile
--- linux.2.5.40/drivers/char/Makefile	2002-10-02 21:33:52.000000000 +0100
+++ linux.2.5.40-ac1/drivers/char/Makefile	2002-10-02 22:22:56.000000000 +0100
@@ -67,6 +67,7 @@
 obj-$(CONFIG_I8K) += i8k.o
 obj-$(CONFIG_DS1620) += ds1620.o
 obj-$(CONFIG_INTEL_RNG) += i810_rng.o
+obj-$(CONFIG_AMD_RNG) += amd768_rng.o
 obj-$(CONFIG_QIC02_TAPE) += tpqic02.o
 obj-$(CONFIG_FTAPE) += ftape/
 obj-$(CONFIG_H8) += h8.o