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Subject[PATCH] Enabling access to the full nvram memory
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This patch adds a CONFIG_NVRAM_BYTES config-time option and a nvram_bytes
runtime option to drivers/char/nvram.c, to allow one to access the full nvram
without needing extra patching.

The config option appears even when it's not applicable (no problem, since
CONFIG_NVRAM has the same problem). Patches to fix that would be useful.

This patch has not been tested. It might even not compile.


diff -Naur linux-2.4.0-test7-pre5.orig/drivers/char/Config.in linux-2.4.0-test7-pre5/drivers/char/Config.in
--- linux-2.4.0-test7-pre5.orig/drivers/char/Config.in Sat Aug 19 19:54:49 2000
+++ linux-2.4.0-test7-pre5/drivers/char/Config.in Sat Aug 19 20:16:53 2000
@@ -156,6 +156,9 @@

dep_tristate 'Intel i8x0 Random Number Generator support' CONFIG_INTEL_RNG $CONFIG_PCI
tristate '/dev/nvram support' CONFIG_NVRAM
+if [ "$CONFIG_NVRAM" != "n" ]; then
+ int ' default nvram size (bytes)' CONFIG_NVRAM_BYTES 50
+fi
tristate 'Enhanced Real Time Clock Support' CONFIG_RTC
if [ "$CONFIG_IA64" = "y" ]; then
bool 'EFI Real Time Clock Services' CONFIG_EFI_RTC
diff -Naur linux-2.4.0-test7-pre5.orig/drivers/char/nvram.c linux-2.4.0-test7-pre5/drivers/char/nvram.c
--- linux-2.4.0-test7-pre5.orig/drivers/char/nvram.c Sat Aug 19 19:53:28 2000
+++ linux-2.4.0-test7-pre5/drivers/char/nvram.c Sat Aug 19 20:19:57 2000
@@ -26,11 +26,12 @@
* drivers, this is the case on the Atari.
*
*
+ * 1.2 Cesar Barros: added nvram_bytes parameter
* 1.1 Cesar Barros: SMP locking fixes
* added changelog
*/

-#define NVRAM_VERSION "1.1"
+#define NVRAM_VERSION "1.2"

#include <linux/module.h>
#include <linux/config.h>
@@ -115,8 +116,21 @@
#define NVRAM_EXCL 2 /* opened with O_EXCL */

#define RTC_FIRST_BYTE 14 /* RTC register number of first NVRAM byte */
-#define NVRAM_BYTES 50 /* number of NVRAM bytes */

+#if MACH == PC
+#define NVRAM_DEFAULT_BYTES CONFIG_NVRAM_BYTES /* default number of NVRAM bytes */
+#define NVRAM_MIN_BYTES 14 /* minimum number of NVRAM bytes */
+#define NVRAM_MAX_BYTES 128 /* maximum number of NVRAM bytes */
+
+static int nvram_bytes = NVRAM_DEFAULT_BYTES;
+#else
+#define NVRAM_DEFAULT_BYTES 50 /* ignore CONFIG_NVRAM_BYTES */
+#define NVRAM_MIN_BYTES NVRAM_DEFAULT_BYTES
+#define NVRAM_MAX_BYTES NVRAM_DEFAULT_BYTES
+
+#define nvram_bytes NVRAM_DEFAULT_BYTES
+#define NVRAM_BYTES_FIXED
+#endif

static int mach_check_checksum( void );
static void mach_set_checksum( void );
@@ -223,7 +237,7 @@
offset += file->f_pos;
break;
case 2:
- offset += NVRAM_BYTES;
+ offset += nvram_bytes;
break;
}
return( (offset >= 0) ? (file->f_pos = offset) : -EINVAL );
@@ -232,7 +246,7 @@
static ssize_t nvram_read(struct file * file,
char * buf, size_t count, loff_t *ppos )
{
- char contents [NVRAM_BYTES];
+ char contents [NVRAM_MAX_BYTES];
unsigned i = *ppos;
char *tmp;

@@ -241,7 +255,7 @@
if (!nvram_check_checksum_int())
goto checksum_err;

- for (tmp = contents; count-- > 0 && i < NVRAM_BYTES; ++i, ++tmp)
+ for (tmp = contents; count-- > 0 && i < nvram_bytes; ++i, ++tmp)
*tmp = nvram_read_int(i);

spin_unlock_irq (&rtc_lock);
@@ -260,13 +274,13 @@
static ssize_t nvram_write(struct file * file,
const char * buf, size_t count, loff_t *ppos )
{
- char contents [NVRAM_BYTES];
+ char contents [NVRAM_MAX_BYTES];
unsigned i = *ppos;
char * tmp;

/* could comebody please help me indent this better? */
- copy_from_user_ret (contents, buf, (NVRAM_BYTES - i) < count ?
- (NVRAM_BYTES - i) : count,
+ copy_from_user_ret (contents, buf, (nvram_bytes - i) < count ?
+ (nvram_bytes - i) : count,
-EFAULT);

spin_lock_irq (&rtc_lock);
@@ -274,7 +288,7 @@
if (!nvram_check_checksum_int())
goto checksum_err;

- for (tmp = contents; count-- > 0 && i < NVRAM_BYTES; ++i, ++tmp)
+ for (tmp = contents; count-- > 0 && i < nvram_bytes; ++i, ++tmp)
nvram_write_int (*tmp, i);

nvram_set_checksum_int();
@@ -303,7 +317,7 @@

spin_lock_irq (&rtc_lock);

- for( i = 0; i < NVRAM_BYTES; ++i )
+ for( i = 0; i < nvram_bytes; ++i )
nvram_write_int( 0, i );
nvram_set_checksum_int();

@@ -363,12 +377,12 @@
static int nvram_read_proc( char *buffer, char **start, off_t offset,
int size, int *eof, void *data )
{
- unsigned char contents[NVRAM_BYTES];
+ unsigned char contents[NVRAM_MAX_BYTES];
int i, len = 0;
off_t begin = 0;

spin_lock_irq (&rtc_lock);
- for( i = 0; i < NVRAM_BYTES; ++i )
+ for( i = 0; i < nvram_bytes; ++i )
contents[i] = nvram_read_int( i );
spin_unlock_irq (&rtc_lock);

@@ -412,9 +426,36 @@
&nvram_fops
};

+#ifndef NVRAM_BYTES_FIXED
+/* Why is module that easier? */
+#ifdef MODULE
+MODULE_PARM(nvram_bytes,"i");
+#else
+static int __init nvram_bytes_setup (char *str)
+{
+ int opt;
+
+ get_option (&str, &opt);
+
+ if (opt >= NVRAM_MIN_BYTES && opt <= NVRAM_MAX_BYTES)
+ nvram_bytes = opt;
+ else
+ printk (KERN_ERR "nvram: nvram_bytes out of bounds, using default of %d\n", NVRAM_BYTES_DEFAULT);
+
+ return 1;
+}
+
+__setup("nvram_bytes=", nvram_bytes_setup);
+#endif
+#endif

static int __init nvram_init(void)
{
+#if defined (MODULE) && !defined (NVRAM_BYTES_FIXED)
+ if (nvram_bytes < NVRAM_MIN_BYTES || nvram_bytes > NVRAM_MAX_BYTES)
+ goto out_of_bounds;
+#endif
+
/* First test whether the driver should init at all */
if (!CHECK_DRIVER_INIT())
return( -ENXIO );
@@ -423,6 +464,12 @@
misc_register( &nvram_dev );
create_proc_read_entry("driver/nvram",0,0,nvram_read_proc,NULL);
return( 0 );
+
+#if defined (MODULE) && !defined (NVRAM_BYTES_FIXED)
+out_of_bounds:
+ printk (KERN_ERR "nvram: nvram_bytes out of bounds\n");
+ return -EINVAL;
+#endif
}

static void __exit nvram_cleanup_module (void)
--
Cesar Eduardo Barros
cesarb@nitnet.com.br
cesarb@dcc.ufrj.br
-
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