Date: Tue, 18 Nov 2014 01:55:30 +0000 From: bugzilla-noreply@freebsd.org To: freebsd-arm@FreeBSD.org Subject: [Bug 195009] [patch]: [arm] Use 400 kHz as the default OMAP4 I2C bus speed Message-ID: <bug-195009-7-zVkdtLEIM4@https.bugs.freebsd.org/bugzilla/> In-Reply-To: <bug-195009-7@https.bugs.freebsd.org/bugzilla/> References: <bug-195009-7@https.bugs.freebsd.org/bugzilla/>
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https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=195009 --- Comment #3 from commit-hook@freebsd.org --- A commit references this bug: Author: ian Date: Tue Nov 18 01:54:33 UTC 2014 New revision: 274641 URL: https://svnweb.freebsd.org/changeset/base/274641 Log: Allow i2c bus speed to be configured via hints, FDT data, and sysctl. The current support for controlling i2c bus speed is an inconsistant mess. There are 4 symbolic speed values defined, UNKNOWN, SLOW, FAST, FASTEST. It seems to be universally assumed that SLOW means the standard 100KHz rate from the original spec. Nothing ever calls iicbus_reset() with a speed of FAST, although some drivers would treat it as the 400KHz standard speed. Mostly iicbus_reset() is called with the speed set to UNKNOWN or FASTEST, and there's really no telling what any individual driver will do with those. The speed of an i2c bus is limited by the speed of the slowest device on the bus. This means that generally the bus speed needs to be configured based on the board/system and the components within it. Historically for i2c we've configured with device hints. Newer systems use FDT data and it documents a clock-frequency property for i2c busses. Hobbyists and developers are likely to want on the fly changes. These changes provide all 3 methods, but do not require any existing drivers to change to use the new facilities. This adds an iicbus method, iicbus_get_frequency(dev, speed) that gets the frequency for the requested symbolic speed. If the symbolic speed is SLOW or if there is no speed configured for the bus, the returned value is 100KHz, always. Otherwise, if bus speed is configured by hints, fdt, tunable, or sysctl, that speed is returned. It also adds a helper function, iicbus_init_frequency() that any bus driver subclassed from iicbus can initialize the frequency from some other source of info. Initial driver implementations are provided for Freescale and TI. Differential Revision: https://reviews.freebsd.org/D1174 PR: 195009 Changes: head/sys/arm/freescale/imx/imx_i2c.c head/sys/arm/ti/ti_i2c.c head/sys/dev/iicbus/iicbus.c head/sys/dev/iicbus/iicbus.h head/sys/dev/iicbus/iicbus_if.m head/sys/dev/ofw/ofw_iicbus.c -- You are receiving this mail because: You are the assignee for the bug.
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