34199ee049
Usually it is sufficient to use iicbus_transfer_excl(), or one of the higher-level convenience functions that use it, to reserve the bus for the duration of each register access. Occasionally it is important that a series of accesses or read-modify-write operations must be done without any other intervening access to the device, to prevent corrupting state. Without support for nested request/release, slave device drivers would have to stop using high-level convenience functions and resort to working with arrays of iic_msg structs just for a few operations (often involving one-time device setup or infrequent configuration changes). The changes here appear large from a glance at the diff, but in fact they're nearly trivial, and the large diff is because of changes in indentation and the re-wrapping of comments caused by that. One notable change is that iicbus_release_bus() now ignores the IICBUS_CALLBACK(IIC_RELEASE_BUS) return value. The old error handling left the bus in a kind of limbo state where it was still owned at the iicbus layer, but drivers rarely check the return of the release call, and it's unclear what they would do to recover from an error return anyway. No existing low-level drivers return any kind of error from IIC_RELEASE_BUS except one EINVAL for "you don't own the bus", to which the right response is probably to carry on with the process of releasing the reference to the bus anyway.
80 lines
2.7 KiB
C
80 lines
2.7 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_int owncount; /* iicbus ownership nesting count */
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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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struct resource_list rl;
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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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