844aff82a6
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
78 lines
2.6 KiB
C
78 lines
2.6 KiB
C
/*-
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* Copyright (c) 1998 Nicolas Souchu
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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* $FreeBSD$
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*
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*/
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#ifndef __IICBUS_H
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#define __IICBUS_H
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#include <sys/_lock.h>
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#include <sys/_mutex.h>
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#define IICBUS_IVAR(d) (struct iicbus_ivar *) device_get_ivars(d)
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#define IICBUS_SOFTC(d) (struct iicbus_softc *) device_get_softc(d)
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struct iicbus_softc
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{
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device_t dev; /* Myself */
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device_t owner; /* iicbus owner device structure */
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u_char started; /* address of the 'started' slave
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* 0 if no start condition succeeded */
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u_char strict; /* deny operations that violate the
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* I2C protocol */
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struct mtx lock;
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u_int bus_freq; /* Configured bus Hz. */
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};
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struct iicbus_ivar
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{
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uint32_t addr;
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bool nostop;
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};
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enum {
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IICBUS_IVAR_ADDR, /* Address or base address */
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IICBUS_IVAR_NOSTOP, /* nostop defaults */
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};
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#define IICBUS_ACCESSOR(A, B, T) \
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__BUS_ACCESSOR(iicbus, A, IICBUS, B, T)
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IICBUS_ACCESSOR(addr, ADDR, uint32_t)
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IICBUS_ACCESSOR(nostop, NOSTOP, bool)
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#define IICBUS_LOCK(sc) mtx_lock(&(sc)->lock)
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#define IICBUS_UNLOCK(sc) mtx_unlock(&(sc)->lock)
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#define IICBUS_ASSERT_LOCKED(sc) mtx_assert(&(sc)->lock, MA_OWNED)
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int iicbus_generic_intr(device_t dev, int event, char *buf);
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void iicbus_init_frequency(device_t dev, u_int bus_freq);
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extern driver_t iicbus_driver;
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extern devclass_t iicbus_devclass;
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#endif
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