Benjamin Herrenschmidt wrote:
On Thu, 2009-07-02 at 17:12 +0100, Martyn Welch wrote:
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.we...@gefanuc.com>

What about other archs that use this driver ? They would also need
that new nvram_size() ...
I'm fairly confident that this driver is solely used by the PowerPC architecture. The config option being set in arch/powerpc/Kconfig[1]. Other than the obvious matches in drivers/char/Makefile[2] and powerpc defconfigs, the only other places I can find the option being used are:

* As a requirement for CONFIG_NVRAM on the PowerPC platform in drivers/char/Kconfig[3] * In "include/config/auto.conf" and "include/linux/autoconf.h". Are these for generation of generic configs?

Martyn

[1] http://git.kernel.org/gitweb.cgi?p=linux/kernel/git/benh/powerpc.git;a=blob;f=arch/powerpc/Kconfig#l145 [2] http://git.kernel.org/gitweb.cgi?p=linux/kernel/git/benh/powerpc.git;a=blob;f=drivers/char/Makefile#l83 [3] http://git.kernel.org/gitweb.cgi?p=linux/kernel/git/benh/powerpc.git;a=blob;f=drivers/char/Kconfig#l777
BTW. This patch touches non-arch code so should at least be CCed to lkml

Cheers,
Ben.

---

 arch/powerpc/include/asm/nvram.h |    3 +++
 arch/powerpc/kernel/setup_32.c   |    8 ++++++++
 drivers/char/generic_nvram.c     |   27 ++++++++++++++++++++-------
 3 files changed, 31 insertions(+), 7 deletions(-)

diff --git a/arch/powerpc/include/asm/nvram.h b/arch/powerpc/include/asm/nvram.h
index efde5ac..71df8b2 100644
--- a/arch/powerpc/include/asm/nvram.h
+++ b/arch/powerpc/include/asm/nvram.h
@@ -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_size(void);
+
 /* Normal access to NVRAM */
 extern unsigned char nvram_read_byte(int i);
 extern void nvram_write_byte(unsigned char c, int i);
diff --git a/arch/powerpc/kernel/setup_32.c b/arch/powerpc/kernel/setup_32.c
index 1d15424..28f7570 100644
--- a/arch/powerpc/kernel/setup_32.c
+++ b/arch/powerpc/kernel/setup_32.c
@@ -208,6 +208,14 @@ void nvram_write_byte(unsigned char val, int addr)
 }
 EXPORT_SYMBOL(nvram_write_byte);
+ssize_t nvram_size(void)
+{
+       if (ppc_md.nvram_size)
+               return ppc_md.nvram_size();
+       return -1;
+}
+EXPORT_SYMBOL(nvram_size);
+
 void nvram_sync(void)
 {
        if (ppc_md.nvram_sync)
diff --git a/drivers/char/generic_nvram.c b/drivers/char/generic_nvram.c
index a00869c..e5f71f3 100644
--- a/drivers/char/generic_nvram.c
+++ b/drivers/char/generic_nvram.c
@@ -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_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_size();
+       if (nvram_len < 0)
+               nvram_len = NVRAM_SIZE;
+
+out:
+       return ret;
 }
void __exit nvram_cleanup(void)



--
Martyn Welch MEng MPhil MIET (Principal Software Engineer)   T:+44(0)1327322748
GE Fanuc Intelligent Platforms Ltd,        |Registered in England and Wales
Tove Valley Business Park, Towcester,      |(3828642) at 100 Barbirolli Square,
Northants, NN12 6PF, UK T:+44(0)1327359444 |Manchester,M2 3AB  VAT:GB 927559189
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