Hi!
I've been trying to come up with a method to automatically load the via-rng.ko
kernel module on systems that support the hardware RNG.
Right now the kernel builds the module, but almost nobody uses it, since it
is not automatically loaded.
I was thinking of creating a platform device from arch/x86/kernel/cpu/centaur.c
and then binding the via-rng.c driver to that platform device. I've cooked
up a patch for this (see below), but it doesn't seem to work, all I get is
a very early kernel oops.
Maybe it is too early during kernel startup to create a platform_device?
Does anyone have an idea how to solve the problem? Is there a better method
than a platform device?
Right now, there also are three flavours of hardware RNG and in order to
support the Nano CPU, I need to be able to differentiate the different hardware
from via-rng.c. The identification is based on CPUID flags. I have a patch to
use CPUID from the via-rng.c, but think it's not clean. The platform_device
method would allow me to use some platform_data to pass information about the
CPU stepping to via_rng. What do you think about this?
Regards,
diff --git a/arch/x86/kernel/cpu/centaur.c b/arch/x86/kernel/cpu/centaur.c
index c95e831..422502b 100644
--- a/arch/x86/kernel/cpu/centaur.c
+++ b/arch/x86/kernel/cpu/centaur.c
@@ -1,6 +1,7 @@
#include <linux/bitops.h>
#include <linux/kernel.h>
#include <linux/init.h>
+#include <linux/platform_device.h>
#include <asm/processor.h>
#include <asm/e820.h>
@@ -239,6 +240,9 @@ static void __cpuinit winchip2_protect_mcr(void)
}
#endif /* CONFIG_X86_OOSTORE */
+/* fake device for request_firmware */
+static struct platform_device *via_rng_pdev;
+
#define ACE_PRESENT (1 << 6)
#define ACE_ENABLED (1 << 7)
#define ACE_FCR (1 << 28) /* MSR_VIA_FCR */
@@ -271,6 +275,13 @@ static void __cpuinit init_c3(struct cpuinfo_x86 *c)
printk(KERN_INFO "CPU: Enabled h/w RNG\n");
}
+ if (tmp & RNG_PRESENT)
+ via_rng_pdev =
+ platform_device_register_simple("via-rng", -1,
+ NULL, 0);
+ if (!via_rng_pdev)
+ printk(KERN_ERR "Cannot register VIA RNG device\n");
+
/* store Centaur Extended Feature Flags as
* word 5 of the CPU capability bit array
*/
diff --git a/drivers/char/hw_random/via-rng.c b/drivers/char/hw_random/via-rng.c
index 4e9573c..7b62857 100644
--- a/drivers/char/hw_random/via-rng.c
+++ b/drivers/char/hw_random/via-rng.c
@@ -7,6 +7,7 @@
*
* Hardware driver for the Intel/AMD/VIA Random Number Generators (RNG)
* (c) Copyright 2003 Red Hat Inc <jgarzik@xxxxxxxxxx>
+ * (c) Copyright 2009 Harald Welte <laforge@xxxxxxxxxxxx>
*
* derived from
*
@@ -28,6 +29,7 @@
#include <linux/kernel.h>
#include <linux/hw_random.h>
#include <linux/delay.h>
+#include <linux/platform_device.h>
#include <asm/io.h>
#include <asm/msr.h>
#include <asm/cpufeature.h>
@@ -171,7 +173,6 @@ static int via_rng_init(struct hwrng *rng)
return 0;
}
-
static struct hwrng via_rng = {
.name = "via",
.init = via_rng_init,
@@ -179,13 +180,10 @@ static struct hwrng via_rng = {
.data_read = via_rng_data_read,
};
-
-static int __init mod_init(void)
+static int __init via_rng_probe(struct platform_device *pdev)
{
int err;
- if (!cpu_has_xstore)
- return -ENODEV;
printk(KERN_INFO "VIA RNG detected\n");
err = hwrng_register(&via_rng);
if (err) {
@@ -197,9 +195,33 @@ out:
return err;
}
-static void __exit mod_exit(void)
+static int __exit via_rng_remove(struct platform_device *pdev)
{
hwrng_unregister(&via_rng);
+
+ return 0;
+}
+
+static struct platform_driver via_rng_driver = {
+ .driver = {
+ .name = "via-rng",
+ .owner = THIS_MODULE,
+ },
+ .probe = via_rng_probe,
+ .remove = __exit_p(via_rng_remove),
+};
+
+static int __init mod_init(void)
+{
+ if (!cpu_has_xstore)
+ return -ENODEV;
+
+ return platform_driver_register(&via_rng_driver);
+}
+
+static void __exit mod_exit(void)
+{
+ platform_driver_unregister(&via_rng_driver);
}
module_init(mod_init);
--
- Harald Welte <HaraldWelte@xxxxxxxxxxx> http://linux.via.com.tw/
============================================================================
VIA Open Source Liaison
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