linux-kernel - Re: [PATCH 3/4] arm: am33xx: DT quirks for am33xx based beaglebone variants

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Date:	Thu, 19 Feb 2015 10:16:57 -0800
From:	Tony Lindgren <tony@...mide.com>
To:	Pantelis Antoniou <pantelis.antoniou@...sulko.com>
Cc:	Grant Likely <grant.likely@...retlab.ca>,
	Matt Porter <matt.porter@...aro.org>,
	Koen Kooi <koen@...inion.thruhere.net>,
	Guenter Roeck <linux@...ck-us.net>,
	Ludovic Desroches <ludovic.desroches@...el.com>,
	Rob Herring <robherring2@...il.com>,
	Nicolas Ferre <nicolas.ferre@...el.com>,
	devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org,
	Pantelis Antoniou <panto@...oniou-consulting.com>
Subject: Re: [PATCH 3/4] arm: am33xx: DT quirks for am33xx based beaglebone
 variants

* Pantelis Antoniou <pantelis.antoniou@...sulko.com> [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?

Regards,

Tony
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