Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752700AbbBSS20 (ORCPT ); Thu, 19 Feb 2015 13:28:26 -0500 Received: from li42-95.members.linode.com ([209.123.162.95]:36714 "EHLO li42-95.members.linode.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751728AbbBSS2Z convert rfc822-to-8bit (ORCPT ); Thu, 19 Feb 2015 13:28:25 -0500 Subject: Re: [PATCH 3/4] arm: am33xx: DT quirks for am33xx based beaglebone variants Mime-Version: 1.0 (Mac OS X Mail 8.2 \(2070.6\)) Content-Type: text/plain; charset=utf-8 From: Pantelis Antoniou In-Reply-To: <20150219181656.GF32521@atomide.com> Date: Thu, 19 Feb 2015 20:28:13 +0200 Cc: Grant Likely , Matt Porter , Koen Kooi , Guenter Roeck , Ludovic Desroches , Rob Herring , Nicolas Ferre , devicetree@vger.kernel.org, Linux Kernel Mailing List , linux-arm-kernel@lists.infradead.org Content-Transfer-Encoding: 8BIT Message-Id: <9C7BFC7C-0751-4233-927F-D01AF078704B@antoniou-consulting.com> References: <1424271576-1952-1-git-send-email-pantelis.antoniou@konsulko.com> <1424271576-1952-4-git-send-email-pantelis.antoniou@konsulko.com> <20150219181656.GF32521@atomide.com> To: Tony Lindgren X-Mailer: Apple Mail (2.2070.6) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2330 Lines: 62 Hi Tony, > On Feb 19, 2015, at 20:16 , Tony Lindgren wrote: > > * Pantelis Antoniou [150218 07:03]: >> Implement DT quirks for the am33xx beaglebone boards. >> --- /dev/null >> +++ b/arch/arm/mach-omap2/am33xx-dt-quirks.c > ... >> + >> +/* >> + * The board IDs for am33xx board are in an I2C EEPROM >> + * We are very early in the boot process so we have to >> + * read the EEPROM directly without using the I2C layer. >> + * >> + * Note that we rely on the bootloader setting up the muxes >> + * (which is the case for u-boot). >> + */ >> + >> +/* I2C Status Register (OMAP_I2C_STAT): */ >> +#define OMAP_I2C_STAT_XDR (1 << 14) /* TX Buffer draining */ >> +#define OMAP_I2C_STAT_RDR (1 << 13) /* RX Buffer draining */ >> +#define OMAP_I2C_STAT_BB (1 << 12) /* Bus busy */ >> +#define OMAP_I2C_STAT_ROVR (1 << 11) /* Receive overrun */ >> +#define OMAP_I2C_STAT_XUDF (1 << 10) /* Transmit underflow */ >> +#define OMAP_I2C_STAT_AAS (1 << 9) /* Address as slave */ >> +#define OMAP_I2C_STAT_BF (1 << 8) /* Bus Free */ >> +#define OMAP_I2C_STAT_XRDY (1 << 4) /* Transmit data ready */ >> +#define OMAP_I2C_STAT_RRDY (1 << 3) /* Receive data ready */ >> +#define OMAP_I2C_STAT_ARDY (1 << 2) /* Register access ready */ >> +#define OMAP_I2C_STAT_NACK (1 << 1) /* No ack interrupt enable */ >> +#define OMAP_I2C_STAT_AL (1 << 0) /* Arbitration lost int ena */ > ... > > Uhh I don't like the idea of duplicating the i2c-omap.c driver under > arch/arm.. And in general we should initialize things later rather > than earlier. > > What's stopping doing these quirk checks later on time with just > a regular device driver, something like drivers/misc/bbone-quirks.c? > We have no choice; we are way early in the boot process, right after the device tree unflattening step. I’ve toyed with the idea of using early platform devices but the omap-i2c driver would need some tender love and care to make it work, and I didn’t want to get bogged down with i2c driver details at this point. > Regards, > > Tony Regards — Pantelis -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/