From mboxrd@z Thu Jan 1 00:00:00 1970 From: Shawn Guo Subject: Re: [PATCH v4 08/10] ARM: mxs: add ocotp read function Date: Wed, 12 Jan 2011 14:47:12 +0800 Message-ID: <20110112064711.GG2888@freescale.com> References: <1294297998-26930-1-git-send-email-shawn.guo@freescale.com> <1294297998-26930-9-git-send-email-shawn.guo@freescale.com> <20110111133137.GS12078@pengutronix.de> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Cc: , , , , , , , , , , , , , To: Sascha Hauer Return-path: Received: from am1ehsobe001.messaging.microsoft.com ([213.199.154.204]:6254 "EHLO AM1EHSOBE001.bigfish.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750836Ab1ALGog (ORCPT ); Wed, 12 Jan 2011 01:44:36 -0500 Received: from mail77-am1 (localhost.localdomain [127.0.0.1]) by mail77-am1-R.bigfish.com (Postfix) with ESMTP id C2D681770566 for ; Wed, 12 Jan 2011 06:44:34 +0000 (UTC) Received: from AM1EHSMHS012.bigfish.com (unknown [10.3.201.247]) by mail77-am1.bigfish.com (Postfix) with ESMTP id 4D0B28A804E for ; Wed, 12 Jan 2011 06:44:34 +0000 (UTC) Received: from de01smr02.am.mot.com (de01smr02.freescale.net [10.208.0.151]) by az33egw02.freescale.net (8.14.3/8.14.3) with ESMTP id p0C6iOI8010825 for ; Tue, 11 Jan 2011 23:44:24 -0700 (MST) Received: from ubuntu.localdomain (ubuntu-010192242196.ap.freescale.net [10.192.242.196]) by de01smr02.am.mot.com (8.13.1/8.13.0) with ESMTP id p0C6iMbN016765 for ; Wed, 12 Jan 2011 00:44:22 -0600 (CST) Content-Disposition: inline In-Reply-To: <20110111133137.GS12078@pengutronix.de> Sender: netdev-owner@vger.kernel.org List-ID: Hi Sascha, On Tue, Jan 11, 2011 at 02:31:37PM +0100, Sascha Hauer wrote: > On Thu, Jan 06, 2011 at 03:13:16PM +0800, Shawn Guo wrote: > > Signed-off-by: Shawn Guo > > --- > > Changes for v4: > > - Call cpu_relax() during polling > > > > Changes for v2: > > - Add mutex locking for mxs_read_ocotp() > > - Use type size_t for count and i > > - Add comment for clk_enable/disable skipping > > - Add ERROR bit clearing and polling step > > > > arch/arm/mach-mxs/Makefile | 2 +- > > arch/arm/mach-mxs/include/mach/common.h | 1 + > > arch/arm/mach-mxs/ocotp.c | 79 +++++++++++++++++++++++++++++++ > > 3 files changed, 81 insertions(+), 1 deletions(-) > > create mode 100644 arch/arm/mach-mxs/ocotp.c > > > > diff --git a/arch/arm/mach-mxs/Makefile b/arch/arm/mach-mxs/Makefile > > index 39d3f9c..f23ebbd 100644 > > --- a/arch/arm/mach-mxs/Makefile > > +++ b/arch/arm/mach-mxs/Makefile > > @@ -1,5 +1,5 @@ > > # Common support > > -obj-y := clock.o devices.o gpio.o icoll.o iomux.o system.o timer.o > > +obj-y := clock.o devices.o gpio.o icoll.o iomux.o ocotp.o system.o timer.o > > > > obj-$(CONFIG_SOC_IMX23) += clock-mx23.o mm-mx23.o > > obj-$(CONFIG_SOC_IMX28) += clock-mx28.o mm-mx28.o > > diff --git a/arch/arm/mach-mxs/include/mach/common.h b/arch/arm/mach-mxs/include/mach/common.h > > index 59133eb..cf02552 100644 > > --- a/arch/arm/mach-mxs/include/mach/common.h > > +++ b/arch/arm/mach-mxs/include/mach/common.h > > @@ -13,6 +13,7 @@ > > > > struct clk; > > > > +extern int mxs_read_ocotp(int offset, int count, u32 *values); > > extern int mxs_reset_block(void __iomem *); > > extern void mxs_timer_init(struct clk *, int); > > > > diff --git a/arch/arm/mach-mxs/ocotp.c b/arch/arm/mach-mxs/ocotp.c > > new file mode 100644 > > index 0000000..e2d39aa > > --- /dev/null > > +++ b/arch/arm/mach-mxs/ocotp.c > > @@ -0,0 +1,79 @@ > > +/* > > + * Copyright 2010 Freescale Semiconductor, Inc. All Rights Reserved. > > + * > > + * 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. > > + */ > > + > > +#include > > +#include > > +#include > > + > > +#include > > + > > +#define BM_OCOTP_CTRL_BUSY (1 << 8) > > +#define BM_OCOTP_CTRL_ERROR (1 << 9) > > +#define BM_OCOTP_CTRL_RD_BANK_OPEN (1 << 12) > > + > > +static DEFINE_MUTEX(ocotp_mutex); > > + > > +int mxs_read_ocotp(unsigned offset, size_t count, u32 *values) > > +{ > > + void __iomem *ocotp_base = MXS_IO_ADDRESS(MXS_OCOTP_BASE_ADDR); > > + int timeout = 0x400; > > + size_t i; > > + > > + mutex_lock(&ocotp_mutex); > > + > > + /* > > + * clk_enable(hbus_clk) for ocotp can be skipped > > + * as it must be on when system is running. > > + */ > > + > > + /* try to clear ERROR bit */ > > + __mxs_clrl(BM_OCOTP_CTRL_ERROR, ocotp_base); > > This operation does not try to clear the error bit but actually clears > it... > > > + > > + /* check both BUSY and ERROR cleared */ > > + while ((__raw_readl(ocotp_base) & > > + (BM_OCOTP_CTRL_BUSY | BM_OCOTP_CTRL_ERROR)) && --timeout) > > + cpu_relax(); > > ...which means you do not have to poll the error bit here... > > > + > > + if (unlikely(!timeout)) > > + goto error_unlock; > > + > > + /* open OCOTP banks for read */ > > + __mxs_setl(BM_OCOTP_CTRL_RD_BANK_OPEN, ocotp_base); > > + > > + /* approximately wait 32 hclk cycles */ > > + udelay(1); > > + > > + /* poll BUSY bit becoming cleared */ > > + timeout = 0x400; > > + while ((__raw_readl(ocotp_base) & BM_OCOTP_CTRL_BUSY) && --timeout) > > + cpu_relax(); > > ...which means you can factor out a ocotp_wait_busy function and let the > code speak instead of the comments. > > > + > > + if (unlikely(!timeout)) > > + goto error_unlock; > > + > > + for (i = 0; i < count; i++, offset += 4) > > + *values++ = __raw_readl(ocotp_base + offset); > > The registers in the ocotp are 16 byte aligned. Does it really make > sense to provide a function allowing to read the gaps between the > registers? > Good catch. The count was added to ease the consecutive otp word reading, as there is bank open/close cost for otp read. What about the following changes? int mxs_read_ocotp(unsigned offset, size_t otp_word_cnt, u32 *values) { ...... for (i = 0; i < otp_word_cnt; i++, offset += 0x10) *values++ = __raw_readl(ocotp_base + offset); ...... } -- Regards, Shawn