[PATCH] arm: tegra: fuse: export chip id and revision

[PATCH] arm: tegra: fuse: export chip id and revision

[Danny Huang]

Expose tegra chip id and revision in /proc/cpu/chipinfo for user mode
usage.

Signed-off-by: Danny Huang <dahuang@nvidia.com>
---
 arch/arm/mach-tegra/fuse.c | 19 +++++++++++++++++++
 1 file changed, 19 insertions(+)

diff --git a/arch/arm/mach-tegra/fuse.c b/arch/arm/mach-tegra/fuse.c
index f7db078..7895542 100644
--- a/arch/arm/mach-tegra/fuse.c
+++ b/arch/arm/mach-tegra/fuse.c
@@ -20,6 +20,7 @@
 #include <linux/kernel.h>
 #include <linux/io.h>
 #include <linux/export.h>
+#include <linux/proc_fs.h>
 #include <linux/tegra-soc.h>
 
 #include "fuse.h"
@@ -43,6 +44,7 @@ enum tegra_revision tegra_revision;
 
 static int tegra_fuse_spare_bit;
 static void (*tegra_init_speedo_data)(void);
+static struct proc_dir_entry *proc_entry;
 
 /* The BCT to use at boot is specified by board straps that can be read
  * through a APB misc register and decoded. 2 bits, i.e. 4 possible BCTs.
@@ -161,3 +163,20 @@ unsigned long long tegra_chip_uid(void)
 	return (hi << 32ull) | lo;
 }
 EXPORT_SYMBOL(tegra_chip_uid);
+
+static int show_chip_info(char *page, char **start, off_t offset,
+			    int count, int *eof, void *data)
+{
+	return snprintf(page, count, "tegra_chip_id: %d\ntegra_chip_rev: %d\n",
+			tegra_chip_id, tegra_revision);
+}
+
+static int __init tegra_chip_info(void)
+{
+	proc_entry = create_proc_entry("cpu/chipinfo", S_IRUGO, NULL);
+	if (proc_entry)
+		proc_entry->read_proc = show_chip_info;
+	return 0;
+}
+
+late_initcall(tegra_chip_info);
-- 
1.8.1.5

[PATCH] arm: tegra: fuse: export chip id and revision

[Shawn Guo]

On Mon, Mar 11, 2013 at 08:37:21PM +0800, Danny Huang wrote:
> Expose tegra chip id and revision in /proc/cpu/chipinfo for user mode
> usage.

It should probably be done in a more generic way.  Check it out
Documentation/ABI/testing/sysfs-devices-soc.

Shawn

[PATCH] arm: tegra: fuse: export chip id and revision

[Stephen Warren]

On 03/11/2013 06:37 AM, Danny Huang wrote:
> Expose tegra chip id and revision in /proc/cpu/chipinfo for user mode
> usage.

I agree with Shawn's comments, but I have a few other comments here too
for the record.

Nit: "Tegra" and "ID" above should be capitalized as I've done so in
this sentence.

> diff --git a/arch/arm/mach-tegra/fuse.c b/arch/arm/mach-tegra/fuse.c

> +static int __init tegra_chip_info(void)
> +{
> +	proc_entry = create_proc_entry("cpu/chipinfo", S_IRUGO, NULL);
> +	if (proc_entry)
> +		proc_entry->read_proc = show_chip_info;
> +	return 0;
> +}
> +
> +late_initcall(tegra_chip_info);

Please don't introduce any more initcalls. Especially initcalls that are
not conditional on the run-time (rather than compile-time) SoC. This
code may be compiled into a kernel that supports SoCs other than Tegra.
However, tegra_chip_info() shouldn't run on those SoCs.

It'd probably be simplest to just perform this initialization as part of
the already-existing tegra_init_fuse(). If not, please call this
initialization function from one of the initialization functions in
arch/arm/mach-tegra/common.c. Both those cases only execute on Tegra.

[PATCH] arm: tegra: fuse: export chip id and revision

[Russell King - ARM Linux]

On Mon, Mar 11, 2013 at 08:37:21PM +0800, Danny Huang wrote:
> Expose tegra chip id and revision in /proc/cpu/chipinfo for user mode
> usage.

I thought we weren't exporting this stuff out via procfs, but had a
soc specific way to do it - drivers/base/soc.c ?  We have soc_id and
revision attributes there... it seems to do what you want already.