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powerpc/nvram: Enable use Generic NVRAM driver for different size chips

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Remove the reliance on a staticly defined NVRAM size, allowing
platforms to support NVRAMs with sizes differing from the standard.

A fall back value is provided for platforms not supporting this extension.

Signed-off-by: Martyn Welch <martyn.welch@gefanuc.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
This commit is contained in:
Martyn Welch 2009-08-13 09:03:02 +01:00 committed by Benjamin Herrenschmidt
parent 1d6ed32226
commit d331d8305c
3 changed files with 31 additions and 7 deletions
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3
arch/powerpc/include/asm/nvram.h
View file

@ -107,6 +107,9 @@ extern void pmac_xpram_write(int xpaddr, u8 data);
/* Synchronize NVRAM */
extern void nvram_sync(void);
/* Determine NVRAM size */
extern ssize_t nvram_get_size(void);
/* Normal access to NVRAM */
extern unsigned char nvram_read_byte(int i);
extern void nvram_write_byte(unsigned char c, int i);

8
arch/powerpc/kernel/setup_32.c
View file

@ -210,6 +210,14 @@ void nvram_write_byte(unsigned char val, int addr)
}
EXPORT_SYMBOL(nvram_write_byte);
ssize_t nvram_get_size(void)
{
if (ppc_md.nvram_size)
return ppc_md.nvram_size();
return -1;
}
EXPORT_SYMBOL(nvram_get_size);
void nvram_sync(void)
{
if (ppc_md.nvram_sync)

27
drivers/char/generic_nvram.c
View file

@ -2,7 +2,7 @@
* Generic /dev/nvram driver for architectures providing some
* "generic" hooks, that is :
*
* nvram_read_byte, nvram_write_byte, nvram_sync
* nvram_read_byte, nvram_write_byte, nvram_sync, nvram_get_size
*
* Note that an additional hook is supported for PowerMac only
* for getting the nvram "partition" informations
@ -28,6 +28,8 @@
#define NVRAM_SIZE 8192
static ssize_t nvram_len;
static loff_t nvram_llseek(struct file *file, loff_t offset, int origin)
{
lock_kernel();
@ -36,7 +38,7 @@ static loff_t nvram_llseek(struct file *file, loff_t offset, int origin)
offset += file->f_pos;
break;
case 2:
offset += NVRAM_SIZE;
offset += nvram_len;
break;
}
if (offset < 0) {
@ -56,9 +58,9 @@ static ssize_t read_nvram(struct file *file, char __user *buf,
if (!access_ok(VERIFY_WRITE, buf, count))
return -EFAULT;
if (*ppos >= NVRAM_SIZE)
if (*ppos >= nvram_len)
return 0;
for (i = *ppos; count > 0 && i < NVRAM_SIZE; ++i, ++p, --count)
for (i = *ppos; count > 0 && i < nvram_len; ++i, ++p, --count)
if (__put_user(nvram_read_byte(i), p))
return -EFAULT;
*ppos = i;
@ -74,9 +76,9 @@ static ssize_t write_nvram(struct file *file, const char __user *buf,
if (!access_ok(VERIFY_READ, buf, count))
return -EFAULT;
if (*ppos >= NVRAM_SIZE)
if (*ppos >= nvram_len)
return 0;
for (i = *ppos; count > 0 && i < NVRAM_SIZE; ++i, ++p, --count) {
for (i = *ppos; count > 0 && i < nvram_len; ++i, ++p, --count) {
if (__get_user(c, p))
return -EFAULT;
nvram_write_byte(c, i);
@ -133,9 +135,20 @@ static struct miscdevice nvram_dev = {
int __init nvram_init(void)
{
int ret = 0;
printk(KERN_INFO "Generic non-volatile memory driver v%s\n",
NVRAM_VERSION);
return misc_register(&nvram_dev);
ret = misc_register(&nvram_dev);
if (ret != 0)
goto out;
nvram_len = nvram_get_size();
if (nvram_len < 0)
nvram_len = NVRAM_SIZE;
out:
return ret;
}
void __exit nvram_cleanup(void)