RE: [PATCH] powerpc/44x: Support OCM(On Chip Memory) for APM821xx SoC and Bluestone board

-----Original Message-----
From: Josh Boyer [mailto:jwboyer@gmail.com]
Sent: Friday, June 15, 2012 12:47 AM
To: Vinh Nguyen Huu Tuong
Cc: Benjamin Herrenschmidt; Paul Mackerras; Matt Porter; Grant Likely;
Rob Herring; Duc Dang; David S. Miller; Kumar Gala; Li Yang; Ashish
Kalra; Anatolij Gustschin; Liu Gang; linuxppc-dev@lists.ozlabs.org;
linux-kernel@vger.kernel.org; devicetree-discuss@lists.ozlabs.org
Subject: Re: [PATCH] powerpc/44x: Support OCM(On Chip Memory) for
APM821xx SoC and Bluestone board

On Sun, May 6, 2012 at 11:52 PM, Vinh Nguyen Huu Tuong
[off-list ref] wrote:

quoted

This patch consists of:
- Add driver for OCM component
- Export OCM Information at /sys/class/ocm/ocminfo

Again, apologies for the delay.  Aside from the incorrect sysfs usage I
pointed out in my other reply, I have just a few comments/questions
below.

[Vinh Nguyen] You're welcome. About the files on sysfs, the first place of
ocm is in procfs, but procfs is deprecated and replaced by sysfs, then I
decided to move it to sysfs. With your comments, I think I can move it to
debugfs.

quoted

diff --git a/arch/powerpc/boot/dts/bluestone.dts

b/arch/powerpc/boot/dts/bluestone.dts
index 7bda373..2687c11 100644

--- a/arch/powerpc/boot/dts/bluestone.dts
+++ b/arch/powerpc/boot/dts/bluestone.dts

@@ -107,6 +107,14 @@

=A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0interrupt-parent =3D <&UIC0>;
=A0 =A0 =A0 =A0};

+ =A0 =A0 =A0 OCM1: ocm@400040000 {
+ =A0 =A0 =A0 =A0 =A0 =A0 =A0 compatible =3D "ibm,ocm";
+ =A0 =A0 =A0 =A0 =A0 =A0 =A0 status =3D "ok";
+ =A0 =A0 =A0 =A0 =A0 =A0 =A0 cell-index =3D <1>;
+ =A0 =A0 =A0 =A0 =A0 =A0 =A0 /* configured in U-Boot */
+ =A0 =A0 =A0 =A0 =A0 =A0 =A0 reg =3D <4 0x00040000 0x8000>; /* 32K */
+ =A0 =A0 =A0 };
+
=A0 =A0 =A0 =A0SDR0: sdr {
=A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0compatible =3D "ibm,sdr-apm821xx";
=A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0dcr-reg =3D <0x00e 0x002>; diff --git
a/arch/powerpc/include/asm/ppc4xx_ocm.h
b/arch/powerpc/include/asm/ppc4xx_ocm.h
new file mode 100644
index 0000000..ff7f386

--- /dev/null
+++ b/arch/powerpc/include/asm/ppc4xx_ocm.h

@@ -0,0 +1,47 @@
+/*
+ * PowerPC 4xx OCM memory allocation support
+ *
+ * (C) Copyright 2009, Applied Micro Circuits Corporation
+ * Victor Gallardo (vgallardo@amcc.com)
+ *
+ * See file CREDITS for list of people who contributed to this
+ * project.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of
+ * the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston,
+ * MA 02111-1307 USA
+ */
+
+#ifndef __ASM_POWERPC_PPC4xx_OCM_H__
+#define __ASM_POWERPC_PPC4xx_OCM_H__
+
+#include <linux/types.h>
+
+#define OCM_NON_CACHED 0
+#define OCM_CACHED =A0 =A0 1
+
+#if defined(CONFIG_PPC4xx_OCM)
+
+void *ocm_alloc(phys_addr_t *phys, int size, int align,
+ =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 int flags, const char *owner); void o=

cm_free(const

quoted

+void *virt);
+
+#else
+
+#define ocm_alloc(phys, size, align, flags, owner) =A0 =A0 NULL #defin=

e

quoted

+ocm_free(addr) ((void)0)
+
+#endif /* CONFIG_PPC4xx_OCM */
+
+#endif =A0/* __ASM_POWERPC_PPC4xx_OCM_H__ */

I don't see any users of this header included in the patch.  I'm going
to guess that follow-on drivers/users are queued once this is in the
tree?  Also, you might want to name these 'ppc4xx_ocm_alloc' or
similar.  The concept of OCM isn't limited to ppc4xx or even SoCs, so
just using 'ocm' in the global kernel namespace might not be great.

[Vinh Nguyen] With our plan, the next submit of IBM NEW EMAC will use it
for speedup. About the naming convention, I will change as your comments.

quoted

diff --git a/arch/powerpc/sysdev/ppc4xx_ocm.c

b/arch/powerpc/sysdev/ppc4xx_ocm.c
new file mode 100644
index 0000000..ba3e450

--- /dev/null
+++ b/arch/powerpc/sysdev/ppc4xx_ocm.c

@@ -0,0 +1,420 @@
+#include <linux/kernel.h>
+#include <linux/errno.h>
+#include <linux/proc_fs.h>

Why do you need proc_fs.h?

[Vinh Nguyen] I will remove it.

quoted

+#include <linux/seq_file.h>
+#include <linux/spinlock.h>
+#include <linux/dma-mapping.h>
+#include <linux/list.h>
+#include <asm/uaccess.h>
+#include <asm/prom.h>
+#include <asm/dcr.h>
+#include <asm/rheap.h>
+#include <asm/mmu.h>
+#include <asm/ppc4xx_ocm.h>
+#include <linux/export.h>
+
+#define OCM_DISABLED =A0 0
+#define OCM_ENABLED =A0 =A0 =A0 =A0 =A0 =A01
+
+struct ocm_block {
+ =A0 =A0 =A0 struct list_head =A0 =A0 =A0 =A0list;
+ =A0 =A0 =A0 void __iomem =A0 =A0 =A0 =A0 =A0 =A0*addr;
+ =A0 =A0 =A0 int =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =

=A0 =A0 =A0 =A0 =A0 size;

quoted

+ =A0 =A0 =A0 const char =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0*ow=

ner; };

quoted

+
+/* non-cached or cached region */
+struct ocm_region {
+ =A0 =A0 =A0 phys_addr_t =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 phys;
+ =A0 =A0 =A0 void __iomem =A0 =A0 =A0 =A0 =A0 =A0*virt;
+
+ =A0 =A0 =A0 int =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =

=A0 =A0 =A0 =A0 =A0 memtotal;

quoted

+ =A0 =A0 =A0 int =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =

=A0 =A0 =A0 =A0 =A0 memfree;

quoted

+
+ =A0 =A0 =A0 rh_info_t =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 *rh=

;

quoted

+ =A0 =A0 =A0 struct list_head =A0 =A0 =A0 =A0list;
+};

There's some interesting whitespace usage in these struct definitions.

[Vinh Nguyen] I'll check again and remove them. I used the scripts check
in kernel but it can't remove them all.

josh

I'll update the patch soon but I need send out to internal review first
before sending out to community. It takes one or two week, please be
patient for the next review.

Best regards,
Vinh Nguyen