From mboxrd@z Thu Jan 1 00:00:00 1970 From: Sascha Hauer Subject: Re: [PATCH v4 08/10] ARM: mxs: add ocotp read function Date: Wed, 12 Jan 2011 15:50:36 +0100 Message-ID: <20110112145036.GY12078@pengutronix.de> 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> <20110112064711.GG2888@freescale.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: davem@davemloft.net, gerg@snapgear.com, baruch@tkos.co.il, eric@eukrea.com, bryan.wu@canonical.com, r64343@freescale.com, B32542@freescale.com, u.kleine-koenig@pengutronix.de, lw@karo-electronics.de, w.sang@pengutronix.de, jamie@jamieiles.com, jamie@shareable.org, netdev@vger.kernel.org, linux-arm-kernel@lists.infradead.org To: Shawn Guo Return-path: Received: from metis.ext.pengutronix.de ([92.198.50.35]:50971 "EHLO metis.ext.pengutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751248Ab1ALOu6 (ORCPT ); Wed, 12 Jan 2011 09:50:58 -0500 Content-Disposition: inline In-Reply-To: <20110112064711.GG2888@freescale.com> Sender: netdev-owner@vger.kernel.org List-ID: On Wed, Jan 12, 2011 at 02:47:12PM +0800, Shawn Guo wrote: > 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); > > ...... > } I would rather make a function like this: static u32 ocotp[0x27]; const u32 *mxs_get_ocotp(void) { static int once = 0; if (once) return ocotp /* bank open */ for (i = 0; i < 0x27; i++) ocotp[i] = readl(ocotp_base + 0x20 + i * 0x10) /* bank_close */ once = 1; return ocotp; } -- Pengutronix e.K. | | Industrial Linux Solutions | http://www.pengutronix.de/ | Peiner Str. 6-8, 31137 Hildesheim, Germany | Phone: +49-5121-206917-0 | Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 |