bhnd(4): Implement common API for IOST/IOCTL register access and core reset

[freebsd.git] / sys / dev / bhnd / bhnd_bus_if.m

#-
# Copyright (c) 2015-2016 Landon Fuller <landonf@FreeBSD.org>
# All rights reserved.
#
# Redistribution and use in source and binary forms, with or without
# modification, are permitted provided that the following conditions
# are met:
# 1. Redistributions of source code must retain the above copyright
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#    notice, this list of conditions and the following disclaimer in the
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# $FreeBSD$

#include <sys/types.h>
#include <sys/bus.h>
#include <sys/rman.h>

#include <dev/bhnd/bhnd_types.h>
#include <dev/bhnd/bhnd_erom_types.h>

INTERFACE bhnd_bus;

#
# bhnd(4) bus interface
#

HEADER {
        /* forward declarations */
        struct bhnd_board_info;
        struct bhnd_core_info;
        struct bhnd_chipid;
        struct bhnd_devinfo;
        struct bhnd_resource;
}

CODE {
        #include <sys/systm.h>

        #include <dev/bhnd/bhndvar.h>

        static bhnd_erom_class_t *
        bhnd_bus_null_get_erom_class(driver_t *driver)
        {
                return (NULL);
        }

        static struct bhnd_chipid *
        bhnd_bus_null_get_chipid(device_t dev, device_t child)
        {
                panic("bhnd_bus_get_chipid unimplemented");
        }

        static int
        bhnd_bus_null_read_ioctl(device_t dev, device_t child, uint16_t *ioctl)
        {
                panic("bhnd_bus_read_ioctl unimplemented");
        }


        static int
        bhnd_bus_null_write_ioctl(device_t dev, device_t child, uint16_t value,
            uint16_t mask)
        {
                panic("bhnd_bus_write_ioctl unimplemented");
        }


        static int
        bhnd_bus_null_read_iost(device_t dev, device_t child, uint16_t *iost)
        {
                panic("bhnd_bus_read_iost unimplemented");
        }

        static bool
        bhnd_bus_null_is_hw_suspended(device_t dev, device_t child)
        {
                panic("bhnd_bus_is_hw_suspended unimplemented");
        }

        static int
        bhnd_bus_null_reset_hw(device_t dev, device_t child, uint16_t ioctl)
        {
                panic("bhnd_bus_reset_hw unimplemented");
        }


        static int
        bhnd_bus_null_suspend_hw(device_t dev, device_t child)
        {
                panic("bhnd_bus_suspend_hw unimplemented");
        }

        static bhnd_attach_type
        bhnd_bus_null_get_attach_type(device_t dev, device_t child)
        {
                panic("bhnd_bus_get_attach_type unimplemented");
        }
        
        static bhnd_clksrc
        bhnd_bus_null_pwrctl_get_clksrc(device_t dev, device_t child,
            bhnd_clock clock)
        {
                return (BHND_CLKSRC_UNKNOWN);
        }

        static int
        bhnd_bus_null_pwrctl_gate_clock(device_t dev, device_t child,
            bhnd_clock clock)
        {
                return (ENODEV);
        }

        static int
        bhnd_bus_null_pwrctl_ungate_clock(device_t dev, device_t child,
            bhnd_clock clock)
        {
                return (ENODEV);
        }

        static int
        bhnd_bus_null_read_board_info(device_t dev, device_t child,
            struct bhnd_board_info *info)
        {
                panic("bhnd_bus_read_boardinfo unimplemented");
        }

        static int
        bhnd_bus_null_get_intr_count(device_t dev, device_t child)
        {
                panic("bhnd_bus_get_intr_count unimplemented");
        }

        static int
        bhnd_bus_null_assign_intr(device_t dev, device_t child, int rid)
        {
                panic("bhnd_bus_assign_intr unimplemented");
        }

        static int
        bhnd_bus_null_get_core_ivec(device_t dev, device_t child, u_int intr,
            uint32_t *ivec)
        {
                panic("bhnd_bus_get_core_ivec unimplemented");
        }

        static void
        bhnd_bus_null_child_added(device_t dev, device_t child)
        {
        }

        static int
        bhnd_bus_null_alloc_pmu(device_t dev, device_t child)
        {
                panic("bhnd_bus_alloc_pmu unimplemented");
        }

        static int
        bhnd_bus_null_release_pmu(device_t dev, device_t child)
        {
                panic("bhnd_bus_release_pmu unimplemented");
        }

        static int
        bhnd_bus_null_request_clock(device_t dev, device_t child,
            bhnd_clock clock)
        {
                panic("bhnd_bus_request_clock unimplemented");
        }

        static int
        bhnd_bus_null_enable_clocks(device_t dev, device_t child,
            uint32_t clocks)
        {
                panic("bhnd_bus_enable_clocks unimplemented");
        }
        
        static int
        bhnd_bus_null_request_ext_rsrc(device_t dev, device_t child,
            u_int rsrc)
        {
                panic("bhnd_bus_request_ext_rsrc unimplemented");
        }

        static int
        bhnd_bus_null_release_ext_rsrc(device_t dev, device_t child,
            u_int rsrc)
        {
                panic("bhnd_bus_release_ext_rsrc unimplemented");
        }

        static int
        bhnd_bus_null_read_config(device_t dev, device_t child,
            bus_size_t offset, void *value, u_int width)
        {
                panic("bhnd_bus_null_read_config unimplemented");
        }

        static void
        bhnd_bus_null_write_config(device_t dev, device_t child,
            bus_size_t offset, void *value, u_int width)
        {
                panic("bhnd_bus_null_write_config unimplemented");
        }

        static device_t
        bhnd_bus_null_find_hostb_device(device_t dev)
        {
                return (NULL);
        }

        static bool
        bhnd_bus_null_is_hw_disabled(device_t dev, device_t child)
        {
                panic("bhnd_bus_is_hw_disabled unimplemented");
        }
        
        static int
        bhnd_bus_null_get_probe_order(device_t dev, device_t child)
        {
                panic("bhnd_bus_get_probe_order unimplemented");
        }

        static int
        bhnd_bus_null_get_port_rid(device_t dev, device_t child,
            bhnd_port_type port_type, u_int port, u_int region)
        {
                return (-1);
        }
        
        static int
        bhnd_bus_null_decode_port_rid(device_t dev, device_t child, int type,
            int rid, bhnd_port_type *port_type, u_int *port, u_int *region)
        {
                return (ENOENT);
        }

        static int
        bhnd_bus_null_get_region_addr(device_t dev, device_t child, 
            bhnd_port_type type, u_int port, u_int region, bhnd_addr_t *addr,
            bhnd_size_t *size)
        {
                return (ENOENT);
        }
        
        static int
        bhnd_bus_null_get_nvram_var(device_t dev, device_t child,
            const char *name, void *buf, size_t *size, bhnd_nvram_type type)
        {
                return (ENODEV);
        }

}

/**
 * Return the bhnd(4) bus driver's device enumeration parser class.
 *
 * @param driver        The bhnd bus driver instance.
 */
STATICMETHOD bhnd_erom_class_t * get_erom_class {
        driver_t                        *driver;
} DEFAULT bhnd_bus_null_get_erom_class;

/**
 * Return the active host bridge core for the bhnd bus, if any.
 *
 * @param dev The bhnd bus device.
 *
 * @retval device_t if a hostb device exists
 * @retval NULL if no hostb device is found.
 */
METHOD device_t find_hostb_device {
        device_t dev;
} DEFAULT bhnd_bus_null_find_hostb_device;

/**
 * Return true if the hardware components required by @p child are unpopulated
 * or otherwise unusable.
 *
 * In some cases, enumerated devices may have pins that are left floating, or
 * the hardware may otherwise be non-functional; this method allows a parent
 * device to explicitly specify if a successfully enumerated @p child should
 * be disabled.
 *
 * @param dev The device whose child is being examined.
 * @param child The child device.
 */
METHOD bool is_hw_disabled {
        device_t dev;
        device_t child;
} DEFAULT bhnd_bus_null_is_hw_disabled;

/**
 * Return the probe (and attach) order for @p child. 
 *
 * All devices on the bhnd(4) bus will be probed, attached, or resumed in
 * ascending order; they will be suspended, shutdown, and detached in
 * descending order.
 *
 * The following device methods will be dispatched in ascending probe order
 * by the bus:
 *
 * - DEVICE_PROBE()
 * - DEVICE_ATTACH()
 * - DEVICE_RESUME()
 *
 * The following device methods will be dispatched in descending probe order
 * by the bus:
 *
 * - DEVICE_SHUTDOWN()
 * - DEVICE_DETACH()
 * - DEVICE_SUSPEND()
 *
 * @param dev The device whose child is being examined.
 * @param child The child device.
 *
 * Refer to BHND_PROBE_* and BHND_PROBE_ORDER_* for the standard set of
 * priorities.
 */
METHOD int get_probe_order {
        device_t dev;
        device_t child;
} DEFAULT bhnd_bus_null_get_probe_order;

/**
 * Return the BHND chip identification for the parent bus.
 *
 * @param dev The device whose child is being examined.
 * @param child The child device.
 */
METHOD const struct bhnd_chipid * get_chipid {
        device_t dev;
        device_t child;
} DEFAULT bhnd_bus_null_get_chipid;

/**
 * Return the BHND attachment type of the parent bus.
 *
 * @param dev The device whose child is being examined.
 * @param child The child device.
 *
 * @retval BHND_ATTACH_ADAPTER if the bus is resident on a bridged adapter,
 * such as a WiFi chipset.
 * @retval BHND_ATTACH_NATIVE if the bus provides hardware services (clock,
 * CPU, etc) to a directly attached native host.
 */
METHOD bhnd_attach_type get_attach_type {
        device_t dev;
        device_t child;
} DEFAULT bhnd_bus_null_get_attach_type;

/**
 * Attempt to read the BHND board identification from the parent bus.
 *
 * This relies on NVRAM access, and will fail if a valid NVRAM device cannot
 * be found, or is not yet attached.
 *
 * @param dev The parent of @p child.
 * @param child The bhnd device requesting board info.
 * @param[out] info On success, will be populated with the bhnd(4) device's
 * board information.
 *
 * @retval 0 success
 * @retval ENODEV       No valid NVRAM source could be found.
 * @retval non-zero     If reading @p name otherwise fails, a regular unix
 *                      error code will be returned.
 */
METHOD int read_board_info {
        device_t dev;
        device_t child;
        struct bhnd_board_info *info;
} DEFAULT bhnd_bus_null_read_board_info;

/**
 * Return the number of interrupts to be assigned to @p child via
 * BHND_BUS_ASSIGN_INTR().
 * 
 * @param dev The bhnd bus parent of @p child.
 * @param child The bhnd device for which a count should be returned.
 *
 * @retval 0            If no interrupts should be assigned.
 * @retval non-zero     The count of interrupt resource IDs to be
 *                      assigned, starting at rid 0.
 */
METHOD int get_intr_count {
        device_t dev;
        device_t child;
} DEFAULT bhnd_bus_null_get_intr_count;

/**
 * Assign an interrupt to @p child via bus_set_resource().
 *
 * The default bus implementation of this method should assign backplane
 * interrupt values to @p child.
 *
 * Bridge-attached bus implementations may instead override standard
 * interconnect IRQ assignment, providing IRQs inherited from the parent bus.
 *
 * TODO: Once we can depend on INTRNG, investigate replacing this with a
 * bridge-level interrupt controller.
 * 
 * @param dev The bhnd bus parent of @p child.
 * @param child The bhnd device to which an interrupt should be assigned.
 * @param rid The interrupt resource ID to be assigned.
 *
 * @retval 0            If an interrupt was assigned.
 * @retval non-zero     If assigning an interrupt otherwise fails, a regular
 *                      unix error code will be returned.
 */
METHOD int assign_intr {
        device_t dev;
        device_t child;
        int rid;
} DEFAULT bhnd_bus_null_assign_intr;

/**
 * Return the backplane interrupt vector corresponding to @p child's given
 * @p intr number.
 * 
 * @param dev The bhnd bus parent of @p child.
 * @param child The bhnd device for which the assigned interrupt vector should
 * be queried.
 * @param intr The interrupt number being queried. This is equivalent to the
 * bus resource ID for the interrupt.
 * @param[out] ivec On success, the assigned hardware interrupt vector be
 * written to this pointer.
 *
 * On bcma(4) devices, this returns the OOB bus line assigned to the
 * interrupt.
 *
 * On siba(4) devices, this returns the target OCP slave flag number assigned
 * to the interrupt.
 *
 * @retval 0            success
 * @retval ENXIO        If @p intr exceeds the number of interrupts available
 *                      to @p child.
 */
METHOD int get_core_ivec {
        device_t dev;
        device_t child;
        u_int intr;
        uint32_t *ivec;
} DEFAULT bhnd_bus_null_get_core_ivec;

/**
 * Notify a bhnd bus that a child was added.
 *
 * This method must be called by concrete bhnd(4) driver impementations
 * after @p child's bus state is fully initialized.
 *
 * @param dev The bhnd bus whose child is being added.
 * @param child The child added to @p dev.
 */
METHOD void child_added {
        device_t dev;
        device_t child;
} DEFAULT bhnd_bus_null_child_added;

/**
 * Read the current value of @p child's I/O control register.
 *
 * @param dev The bhnd bus parent of @p child.
 * @param child The bhnd device for which the I/O control register should be
 * read.
 * @param[out] ioctl On success, the I/O control register value.
 *
 * @retval 0 success
 * @retval EINVAL If @p child is not a direct child of @p dev.
 * @retval ENODEV If agent/config space for @p child is unavailable.
 * @retval non-zero If reading the IOCTL register otherwise fails, a regular
 * unix error code will be returned.
 */
METHOD int read_ioctl {
        device_t dev;
        device_t child;
        uint16_t *ioctl;
} DEFAULT bhnd_bus_null_read_ioctl;

/**
 * Write @p value with @p mask to @p child's I/O control register.
 * 
 * @param dev The bhnd bus parent of @p child.
 * @param child The bhnd device for which the I/O control register should
 * be updated.
 * @param value The value to be written (see also BHND_IOCTL_*).
 * @param mask Only the bits defined by @p mask will be updated from @p value.
 * 
 * @retval 0 success
 * @retval EINVAL If @p child is not a direct child of @p dev.
 * @retval ENODEV If agent/config space for @p child is unavailable.
 * @retval non-zero If writing the IOCTL register otherwise fails, a regular
 * unix error code will be returned.
 */
METHOD int write_ioctl {
        device_t dev;
        device_t child;
        uint16_t value;
        uint16_t mask;
} DEFAULT bhnd_bus_null_write_ioctl;

/**
 * Read the current value of @p child's I/O status register.
 *
 * @param dev The bhnd bus parent of @p child.
 * @param child The bhnd device for which the I/O status register should be
 * read.
 * @param[out] iost On success, the I/O status register value.
 * 
 * @retval 0 success
 * @retval EINVAL If @p child is not a direct child of @p dev.
 * @retval ENODEV If agent/config space for @p child is unavailable.
 * @retval non-zero If reading the IOST register otherwise fails, a regular
 * unix error code will be returned.
 */
METHOD int read_iost {
        device_t dev;
        device_t child;
        uint16_t *iost;
} DEFAULT bhnd_bus_null_read_iost;


/**
 * Return true if the given bhnd device's hardware is currently held
 * in a RESET state or otherwise not clocked (BHND_IOCTL_CLK_EN).
 * 
 * @param dev The bhnd bus parent of @p child.
 * @param child The device to query.
 *
 * @retval true If @p child is held in RESET or not clocked (BHND_IOCTL_CLK_EN),
 * or an error occured determining @p child's hardware state.
 * @retval false If @p child is clocked and is not held in RESET.
 */
METHOD bool is_hw_suspended {
        device_t dev;
        device_t child;
} DEFAULT bhnd_bus_null_is_hw_suspended;

/**
 * Place the bhnd(4) device's hardware into a reset state, and then bring the
 * hardware out of reset with BHND_IOCTL_CLK_EN and @p ioctl flags set.
 * 
 * Any clock or resource PMU requests previously made by @p child will be
 * invalidated.
 *
 * @param dev The bhnd bus parent of @p child.
 * @param child The device to be reset.
 * @param ioctl Device-specific core ioctl flags to be supplied on reset
 * (see BHND_IOCTL_*).
 *
 * @retval 0 success
 * @retval non-zero error
 */
METHOD int reset_hw {
        device_t dev;
        device_t child;
        uint16_t ioctl;
} DEFAULT bhnd_bus_null_reset_hw;

/**
 * Suspend @p child's hardware in a low-power reset state.
 *
 * Any clock or resource PMU requests previously made by @p dev will be
 * invalidated.
 *
 * The hardware may be brought out of reset via bhnd_reset_hw().
 *
 * @param dev The bhnd bus parent of @P child.
 * @param dev The device to be suspended.
 *
 * @retval 0 success
 * @retval non-zero error
 */
METHOD int suspend_hw {
        device_t dev;
        device_t child;
} DEFAULT bhnd_bus_null_suspend_hw;

/**
 * If supported by the chipset, return the clock source for the given clock.
 *
 * This function is only supported on early PWRCTL-equipped chipsets
 * that expose clock management via their host bridge interface. Currently,
 * this includes PCI (not PCIe) devices, with ChipCommon core revisions 0-9.
 *
 * @param dev The parent of @p child.
 * @param child The bhnd device requesting a clock source.
 * @param clock The clock for which a clock source will be returned.
 *
 * @retval      bhnd_clksrc             The clock source for @p clock.
 * @retval      BHND_CLKSRC_UNKNOWN     If @p clock is unsupported, or its
 *                                      clock source is not known to the bus.
 */
METHOD bhnd_clksrc pwrctl_get_clksrc {
        device_t dev;
        device_t child;
        bhnd_clock clock;
} DEFAULT bhnd_bus_null_pwrctl_get_clksrc;

/**
 * If supported by the chipset, gate the clock source for @p clock
 *
 * This function is only supported on early PWRCTL-equipped chipsets
 * that expose clock management via their host bridge interface. Currently,
 * this includes PCI (not PCIe) devices, with ChipCommon core revisions 0-9.
 *
 * @param dev The parent of @p child.
 * @param child The bhnd device requesting clock gating.
 * @param clock The clock to be disabled.
 *
 * @retval 0 success
 * @retval ENODEV If bus-level clock source management is not supported.
 * @retval ENXIO If bus-level management of @p clock is not supported.
 */
METHOD int pwrctl_gate_clock {
        device_t dev;
        device_t child;
        bhnd_clock clock;
} DEFAULT bhnd_bus_null_pwrctl_gate_clock;

/**
 * If supported by the chipset, ungate the clock source for @p clock
 *
 * This function is only supported on early PWRCTL-equipped chipsets
 * that expose clock management via their host bridge interface. Currently,
 * this includes PCI (not PCIe) devices, with ChipCommon core revisions 0-9.
 *
 * @param dev The parent of @p child.
 * @param child The bhnd device requesting clock gating.
 * @param clock The clock to be enabled.
 *
 * @retval 0 success
 * @retval ENODEV If bus-level clock source management is not supported.
 * @retval ENXIO If bus-level management of @p clock is not supported.
 */
METHOD int pwrctl_ungate_clock {
        device_t dev;
        device_t child;
        bhnd_clock clock;
} DEFAULT bhnd_bus_null_pwrctl_ungate_clock;

/**
 * Allocate and enable per-core PMU request handling for @p child.
 *
 * The region containing the core's PMU register block (if any) must be
 * allocated via bus_alloc_resource(9) (or bhnd_alloc_resource) before
 * calling BHND_BUS_ALLOC_PMU(), and must not be released until after
 * calling BHND_BUS_RELEASE_PMU().
 *
 * @param dev The parent of @p child.
 * @param child The requesting bhnd device.
 */
METHOD int alloc_pmu {
        device_t dev;
        device_t child;
} DEFAULT bhnd_bus_null_alloc_pmu;

/**
 * Release per-core PMU resources allocated for @p child. Any
 * outstanding PMU requests are discarded.
 *
 * @param dev The parent of @p child.
 * @param child The requesting bhnd device.
 */
METHOD int release_pmu {
        device_t dev;
        device_t child;
} DEFAULT bhnd_bus_null_release_pmu;

/** 
 * Request that @p clock (or faster) be routed to @p child.
 * 
 * @note A driver must ask the bhnd bus to allocate PMU request state
 * via BHND_BUS_ALLOC_PMU() before it can request clock resources.
 *
 * @note Any outstanding PMU clock requests will be discarded upon calling
 * BHND_BUS_RESET_HW() or BHND_BUS_SUSPEND_HW().
 *
 * @param dev The parent of @p child.
 * @param child The bhnd device requesting @p clock.
 * @param clock The requested clock source. 
 *
 * @retval 0 success
 * @retval ENODEV If an unsupported clock was requested.
 * @retval ENXIO If the PMU has not been initialized or is otherwise unvailable.
 */
METHOD int request_clock {
        device_t dev;
        device_t child;
        bhnd_clock clock;
} DEFAULT bhnd_bus_null_request_clock;

/**
 * Request that @p clocks be powered on behalf of @p child.
 *
 * This will power on clock sources (e.g. XTAL, PLL, etc) required for
 * @p clocks and wait until they are ready, discarding any previous
 * requests by @p child.
 *
 * @note A driver must ask the bhnd bus to allocate PMU request state
 * via BHND_BUS_ALLOC_PMU() before it can request clock resources.
 *
 * @note Any outstanding PMU clock requests will be discarded upon calling
 * BHND_BUS_RESET_HW() or BHND_BUS_SUSPEND_HW().
 *
 * @param dev The parent of @p child.
 * @param child The bhnd device requesting @p clock.
 * @param clock The requested clock source.
 *
 * @retval 0 success
 * @retval ENODEV If an unsupported clock was requested.
 * @retval ENXIO If the PMU has not been initialized or is otherwise unvailable.
 */
METHOD int enable_clocks {
        device_t dev;
        device_t child;
        uint32_t clocks;
} DEFAULT bhnd_bus_null_enable_clocks;

/**
 * Power up an external PMU-managed resource assigned to @p child.
 * 
 * @note A driver must ask the bhnd bus to allocate PMU request state
 * via BHND_BUS_ALLOC_PMU() before it can request PMU resources.
 *
 * @note Any outstanding PMU resource requests will be released upon calling
 * BHND_BUS_RESET_HW() or BHND_BUS_SUSPEND_HW().
 *
 * @param dev The parent of @p child.
 * @param child The bhnd device requesting @p rsrc.
 * @param rsrc The core-specific external resource identifier.
 *
 * @retval 0 success
 * @retval ENODEV If the PMU does not support @p rsrc.
 * @retval ENXIO If the PMU has not been initialized or is otherwise unvailable.
 */
METHOD int request_ext_rsrc {
        device_t dev;
        device_t child;
        u_int rsrc;
} DEFAULT bhnd_bus_null_request_ext_rsrc;

/**
 * Power down an external PMU-managed resource assigned to @p child.
 * 
 * @note A driver must ask the bhnd bus to allocate PMU request state
 * via BHND_BUS_ALLOC_PMU() before it can request PMU resources.
 *
 * @param dev The parent of @p child.
 * @param child The bhnd device requesting @p rsrc.
 * @param rsrc The core-specific external resource number.
 *
 * @retval 0 success
 * @retval ENODEV If the PMU does not support @p rsrc.
 * @retval ENXIO If the PMU has not been initialized or is otherwise unvailable.
 */
METHOD int release_ext_rsrc {
        device_t dev;
        device_t child;
        u_int rsrc;
} DEFAULT bhnd_bus_null_release_ext_rsrc;

/**
 * Read @p width bytes at @p offset from the bus-specific agent/config
 * space of @p child.
 *
 * @param dev The parent of @p child.
 * @param child The bhnd device for which @p offset should be read.
 * @param offset The offset to be read.
 * @param[out] value On success, the bytes read at @p offset.
 * @param width The size of the access. Must be 1, 2 or 4 bytes.
 *
 * The exact behavior of this method is bus-specific. On a bcma(4) bus, this
 * method provides access to the first agent port of @p child; on a siba(4) bus,
 * this method provides access to the core's CFG0 register block.
 *
 * @note Device drivers should only use this API for functionality
 * that is not available via another bhnd(4) function.
 *
 * @retval 0 success
 * @retval EINVAL If @p child is not a direct child of @p dev.
 * @retval EINVAL If @p width is not one of 1, 2, or 4 bytes.
 * @retval ENODEV If accessing agent/config space for @p child is unsupported.
 * @retval EFAULT If reading @p width at @p offset exceeds the bounds of
 * the mapped agent/config space  for @p child.
 */
METHOD int read_config {
        device_t dev;
        device_t child;
        bus_size_t offset;
        void *value;
        u_int width;
} DEFAULT bhnd_bus_null_read_config;

/**
 * Read @p width bytes at @p offset from the bus-specific agent/config
 * space of @p child.
 *
 * @param dev The parent of @p child.
 * @param child The bhnd device for which @p offset should be read.
 * @param offset The offset to be written.
 * @param value A pointer to the value to be written.
 * @param width The size of @p value. Must be 1, 2 or 4 bytes.
 *
 * The exact behavior of this method is bus-specific. In the case of
 * bcma(4), this method provides access to the first agent port of @p child.
 *
 * @note Device drivers should only use this API for functionality
 * that is not available via another bhnd(4) function.
 *
 * @retval 0 success
 * @retval EINVAL If @p child is not a direct child of @p dev.
 * @retval EINVAL If @p width is not one of 1, 2, or 4 bytes.
 * @retval ENODEV If accessing agent/config space for @p child is unsupported.
 * @retval EFAULT If reading @p width at @p offset exceeds the bounds of
 * the mapped agent/config space  for @p child.
 */
METHOD int write_config {
        device_t dev;
        device_t child;
        bus_size_t offset;
        const void *value;
        u_int width;
} DEFAULT bhnd_bus_null_write_config;

/**
 * Allocate a bhnd resource.
 *
 * This method's semantics are functionally identical to the bus API of the same
 * name; refer to BUS_ALLOC_RESOURCE for complete documentation.
 */
METHOD struct bhnd_resource * alloc_resource {
        device_t dev;
        device_t child;
        int type;
        int *rid;
        rman_res_t start;
        rman_res_t end;
        rman_res_t count;
        u_int flags;
} DEFAULT bhnd_bus_generic_alloc_resource;

/**
 * Release a bhnd resource.
 *
 * This method's semantics are functionally identical to the bus API of the same
 * name; refer to BUS_RELEASE_RESOURCE for complete documentation.
 */
METHOD int release_resource {
        device_t dev;
        device_t child;
        int type;
        int rid;
        struct bhnd_resource *res;
} DEFAULT bhnd_bus_generic_release_resource;

/**
 * Activate a bhnd resource.
 *
 * This method's semantics are functionally identical to the bus API of the same
 * name; refer to BUS_ACTIVATE_RESOURCE for complete documentation.
 */
METHOD int activate_resource {
        device_t dev;
        device_t child;
        int type;
        int rid;
        struct bhnd_resource *r;
} DEFAULT bhnd_bus_generic_activate_resource;

/**
 * Deactivate a bhnd resource.
 *
 * This method's semantics are functionally identical to the bus API of the same
 * name; refer to BUS_DEACTIVATE_RESOURCE for complete documentation.
 */
METHOD int deactivate_resource {
        device_t dev;
        device_t child;
        int type;
        int rid;
        struct bhnd_resource *r;
} DEFAULT bhnd_bus_generic_deactivate_resource;

/**
 * Return true if @p region_num is a valid region on @p port_num of
 * @p type attached to @p child.
 *
 * @param dev The device whose child is being examined.
 * @param child The child device.
 * @param type The port type being queried.
 * @param port_num The port number being queried.
 * @param region_num The region number being queried.
 */
METHOD bool is_region_valid {
        device_t dev;
        device_t child;
        bhnd_port_type type;
        u_int port_num;
        u_int region_num;
};

/**
 * Return the number of ports of type @p type attached to @p child.
 *
 * @param dev The device whose child is being examined.
 * @param child The child device.
 * @param type The port type being queried.
 */
METHOD u_int get_port_count {
        device_t dev;
        device_t child;
        bhnd_port_type type;
};

/**
 * Return the number of memory regions mapped to @p child @p port of
 * type @p type.
 *
 * @param dev The device whose child is being examined.
 * @param child The child device.
 * @param port The port number being queried.
 * @param type The port type being queried.
 */
METHOD u_int get_region_count {
        device_t dev;
        device_t child;
        bhnd_port_type type;
        u_int port;
};

/**
 * Return the SYS_RES_MEMORY resource-ID for a port/region pair attached to
 * @p child.
 *
 * @param dev The bus device.
 * @param child The bhnd child.
 * @param port_type The port type.
 * @param port_num The index of the child interconnect port.
 * @param region_num The index of the port-mapped address region.
 *
 * @retval -1 No such port/region found.
 */
METHOD int get_port_rid {
        device_t dev;
        device_t child;
        bhnd_port_type port_type;
        u_int port_num;
        u_int region_num;
} DEFAULT bhnd_bus_null_get_port_rid;


/**
 * Decode a port / region pair on @p child defined by @p type and @p rid.
 *
 * @param dev The bus device.
 * @param child The bhnd child.
 * @param type The resource type.
 * @param rid The resource ID.
 * @param[out] port_type The port's type.
 * @param[out] port The port identifier.
 * @param[out] region The identifier of the memory region on @p port.
 * 
 * @retval 0 success
 * @retval non-zero No matching type/rid found.
 */
METHOD int decode_port_rid {
        device_t dev;
        device_t child;
        int type;
        int rid;
        bhnd_port_type *port_type;
        u_int *port;
        u_int *region;
} DEFAULT bhnd_bus_null_decode_port_rid;

/**
 * Get the address and size of @p region on @p port.
 *
 * @param dev The bus device.
 * @param child The bhnd child.
 * @param port_type The port type.
 * @param port The port identifier.
 * @param region The identifier of the memory region on @p port.
 * @param[out] region_addr The region's base address.
 * @param[out] region_size The region's size.
 *
 * @retval 0 success
 * @retval non-zero No matching port/region found.
 */
METHOD int get_region_addr {
        device_t dev;
        device_t child;
        bhnd_port_type port_type;
        u_int port;
        u_int region;
        bhnd_addr_t *region_addr;
        bhnd_size_t *region_size;
} DEFAULT bhnd_bus_null_get_region_addr;

/**
 * Read an NVRAM variable.
 * 
 * It is the responsibility of the bus to delegate this request to
 * the appropriate NVRAM child device, or to a parent bus implementation.
 *
 * @param               dev     The bus device.
 * @param               child   The requesting device.
 * @param               name    The NVRAM variable name.
 * @param[out]          buf     On success, the requested value will be written
 *                              to this buffer. This argment may be NULL if
 *                              the value is not desired.
 * @param[in,out]       size    The capacity of @p buf. On success, will be set
 *                              to the actual size of the requested value.
 * @param               type    The data type to be written to @p buf.
 *
 * @retval 0            success
 * @retval ENOENT       The requested variable was not found.
 * @retval ENOMEM       If @p buf is non-NULL and a buffer of @p size is too
 *                      small to hold the requested value.
 * @retval ENODEV       No valid NVRAM source could be found.
 * @retval EFTYPE       If the @p name's data type cannot be coerced to @p type.
 * @retval ERANGE       If value coercion would overflow @p type.
 * @retval non-zero     If reading @p name otherwise fails, a regular unix
 *                      error code will be returned.
 */
METHOD int get_nvram_var {
        device_t         dev;
        device_t         child;
        const char      *name;
        void            *buf;
        size_t          *size;
        bhnd_nvram_type  type;
} DEFAULT bhnd_bus_null_get_nvram_var;


/** An implementation of bus_read_1() compatible with bhnd_resource */
METHOD uint8_t read_1 {
        device_t dev;
        device_t child;
        struct bhnd_resource *r;
        bus_size_t offset;
}

/** An implementation of bus_read_2() compatible with bhnd_resource */
METHOD uint16_t read_2 {
        device_t dev;
        device_t child;
        struct bhnd_resource *r;
        bus_size_t offset;
}

/** An implementation of bus_read_4() compatible with bhnd_resource */
METHOD uint32_t read_4 {
        device_t dev;
        device_t child;
        struct bhnd_resource *r;
        bus_size_t offset;
}

/** An implementation of bus_write_1() compatible with bhnd_resource */
METHOD void write_1 {
        device_t dev;
        device_t child;
        struct bhnd_resource *r;
        bus_size_t offset;
        uint8_t value;
}

/** An implementation of bus_write_2() compatible with bhnd_resource */
METHOD void write_2 {
        device_t dev;
        device_t child;
        struct bhnd_resource *r;
        bus_size_t offset;
        uint16_t value;
}

/** An implementation of bus_write_4() compatible with bhnd_resource */
METHOD void write_4 {
        device_t dev;
        device_t child;
        struct bhnd_resource *r;
        bus_size_t offset;
        uint32_t value;
}

/** An implementation of bus_read_stream_1() compatible with bhnd_resource */
METHOD uint8_t read_stream_1 {
        device_t dev;
        device_t child;
        struct bhnd_resource *r;
        bus_size_t offset;
}

/** An implementation of bus_read_stream_2() compatible with bhnd_resource */
METHOD uint16_t read_stream_2 {
        device_t dev;
        device_t child;
        struct bhnd_resource *r;
        bus_size_t offset;
}

/** An implementation of bus_read_stream_4() compatible with bhnd_resource */
METHOD uint32_t read_stream_4 {
        device_t dev;
        device_t child;
        struct bhnd_resource *r;
        bus_size_t offset;
}

/** An implementation of bus_write_stream_1() compatible with bhnd_resource */
METHOD void write_stream_1 {
        device_t dev;
        device_t child;
        struct bhnd_resource *r;
        bus_size_t offset;
        uint8_t value;
}

/** An implementation of bus_write_stream_2() compatible with bhnd_resource */
METHOD void write_stream_2 {
        device_t dev;
        device_t child;
        struct bhnd_resource *r;
        bus_size_t offset;
        uint16_t value;
}

/** An implementation of bus_write_stream_4() compatible with bhnd_resource */
METHOD void write_stream_4 {
        device_t dev;
        device_t child;
        struct bhnd_resource *r;
        bus_size_t offset;
        uint32_t value;
}

/** An implementation of bus_read_multi_1() compatible with bhnd_resource */
METHOD void read_multi_1 {
        device_t dev;
        device_t child;
        struct bhnd_resource *r;
        bus_size_t offset;
        uint8_t *datap;
        bus_size_t count;
}

/** An implementation of bus_read_multi_2() compatible with bhnd_resource */
METHOD void read_multi_2 {
        device_t dev;
        device_t child;
        struct bhnd_resource *r;
        bus_size_t offset;
        uint16_t *datap;
        bus_size_t count;
}

/** An implementation of bus_read_multi_4() compatible with bhnd_resource */
METHOD void read_multi_4 {
        device_t dev;
        device_t child;
        struct bhnd_resource *r;
        bus_size_t offset;
        uint32_t *datap;
        bus_size_t count;
}

/** An implementation of bus_write_multi_1() compatible with bhnd_resource */
METHOD void write_multi_1 {
        device_t dev;
        device_t child;
        struct bhnd_resource *r;
        bus_size_t offset;
        uint8_t *datap;
        bus_size_t count;
}

/** An implementation of bus_write_multi_2() compatible with bhnd_resource */
METHOD void write_multi_2 {
        device_t dev;
        device_t child;
        struct bhnd_resource *r;
        bus_size_t offset;
        uint16_t *datap;
        bus_size_t count;
}

/** An implementation of bus_write_multi_4() compatible with bhnd_resource */
METHOD void write_multi_4 {
        device_t dev;
        device_t child;
        struct bhnd_resource *r;
        bus_size_t offset;
        uint32_t *datap;
        bus_size_t count;
}

/** An implementation of bus_read_multi_stream_1() compatible
 *  bhnd_resource */
METHOD void read_multi_stream_1 {
        device_t dev;
        device_t child;
        struct bhnd_resource *r;
        bus_size_t offset;
        uint8_t *datap;
        bus_size_t count;
}

/** An implementation of bus_read_multi_stream_2() compatible
 *  bhnd_resource */
METHOD void read_multi_stream_2 {
        device_t dev;
        device_t child;
        struct bhnd_resource *r;
        bus_size_t offset;
        uint16_t *datap;
        bus_size_t count;
}

/** An implementation of bus_read_multi_stream_4() compatible
 *  bhnd_resource */
METHOD void read_multi_stream_4 {
        device_t dev;
        device_t child;
        struct bhnd_resource *r;
        bus_size_t offset;
        uint32_t *datap;
        bus_size_t count;
}

/** An implementation of bus_write_multi_stream_1() compatible
 *  bhnd_resource */
METHOD void write_multi_stream_1 {
        device_t dev;
        device_t child;
        struct bhnd_resource *r;
        bus_size_t offset;
        uint8_t *datap;
        bus_size_t count;
}

/** An implementation of bus_write_multi_stream_2() compatible with
 *  bhnd_resource */
METHOD void write_multi_stream_2 {
        device_t dev;
        device_t child;
        struct bhnd_resource *r;
        bus_size_t offset;
        uint16_t *datap;
        bus_size_t count;
}

/** An implementation of bus_write_multi_stream_4() compatible with
 *  bhnd_resource */
METHOD void write_multi_stream_4 {
        device_t dev;
        device_t child;
        struct bhnd_resource *r;
        bus_size_t offset;
        uint32_t *datap;
        bus_size_t count;
}

/** An implementation of bus_set_multi_1() compatible with bhnd_resource */
METHOD void set_multi_1 {
        device_t dev;
        device_t child;
        struct bhnd_resource *r;
        bus_size_t offset;
        uint8_t value;
        bus_size_t count;
}

/** An implementation of bus_set_multi_2() compatible with bhnd_resource */
METHOD void set_multi_2 {
        device_t dev;
        device_t child;
        struct bhnd_resource *r;
        bus_size_t offset;
        uint16_t value;
        bus_size_t count;
}

/** An implementation of bus_set_multi_4() compatible with bhnd_resource */
METHOD void set_multi_4 {
        device_t dev;
        device_t child;
        struct bhnd_resource *r;
        bus_size_t offset;
        uint32_t value;
        bus_size_t count;
}

/** An implementation of bus_set_region_1() compatible with bhnd_resource */
METHOD void set_region_1 {
        device_t dev;
        device_t child;
        struct bhnd_resource *r;
        bus_size_t offset;
        uint8_t value;
        bus_size_t count;
}

/** An implementation of bus_set_region_2() compatible with bhnd_resource */
METHOD void set_region_2 {
        device_t dev;
        device_t child;
        struct bhnd_resource *r;
        bus_size_t offset;
        uint16_t value;
        bus_size_t count;
}

/** An implementation of bus_set_region_4() compatible with bhnd_resource */
METHOD void set_region_4 {
        device_t dev;
        device_t child;
        struct bhnd_resource *r;
        bus_size_t offset;
        uint32_t value;
        bus_size_t count;
}

/** An implementation of bus_read_region_1() compatible with bhnd_resource */
METHOD void read_region_1 {
        device_t dev;
        device_t child;
        struct bhnd_resource *r;
        bus_size_t offset;
        uint8_t *datap;
        bus_size_t count;
}

/** An implementation of bus_read_region_2() compatible with bhnd_resource */
METHOD void read_region_2 {
        device_t dev;
        device_t child;
        struct bhnd_resource *r;
        bus_size_t offset;
        uint16_t *datap;
        bus_size_t count;
}

/** An implementation of bus_read_region_4() compatible with bhnd_resource */
METHOD void read_region_4 {
        device_t dev;
        device_t child;
        struct bhnd_resource *r;
        bus_size_t offset;
        uint32_t *datap;
        bus_size_t count;
}

/** An implementation of bus_read_region_stream_1() compatible with
  * bhnd_resource */
METHOD void read_region_stream_1 {
        device_t dev;
        device_t child;
        struct bhnd_resource *r;
        bus_size_t offset;
        uint8_t *datap;
        bus_size_t count;
}

/** An implementation of bus_read_region_stream_2() compatible with
  * bhnd_resource */
METHOD void read_region_stream_2 {
        device_t dev;
        device_t child;
        struct bhnd_resource *r;
        bus_size_t offset;
        uint16_t *datap;
        bus_size_t count;
}

/** An implementation of bus_read_region_stream_4() compatible with
  * bhnd_resource */
METHOD void read_region_stream_4 {
        device_t dev;
        device_t child;
        struct bhnd_resource *r;
        bus_size_t offset;
        uint32_t *datap;
        bus_size_t count;
}

/** An implementation of bus_write_region_1() compatible with bhnd_resource */
METHOD void write_region_1 {
        device_t dev;
        device_t child;
        struct bhnd_resource *r;
        bus_size_t offset;
        uint8_t *datap;
        bus_size_t count;
}

/** An implementation of bus_write_region_2() compatible with bhnd_resource */
METHOD void write_region_2 {
        device_t dev;
        device_t child;
        struct bhnd_resource *r;
        bus_size_t offset;
        uint16_t *datap;
        bus_size_t count;
}

/** An implementation of bus_write_region_4() compatible with bhnd_resource */
METHOD void write_region_4 {
        device_t dev;
        device_t child;
        struct bhnd_resource *r;
        bus_size_t offset;
        uint32_t *datap;
        bus_size_t count;
}

/** An implementation of bus_write_region_stream_1() compatible with
  * bhnd_resource */
METHOD void write_region_stream_1 {
        device_t dev;
        device_t child;
        struct bhnd_resource *r;
        bus_size_t offset;
        uint8_t *datap;
        bus_size_t count;
}

/** An implementation of bus_write_region_stream_2() compatible with
  * bhnd_resource */
METHOD void write_region_stream_2 {
        device_t dev;
        device_t child;
        struct bhnd_resource *r;
        bus_size_t offset;
        uint16_t *datap;
        bus_size_t count;
}

/** An implementation of bus_write_region_stream_4() compatible with
  * bhnd_resource */
METHOD void write_region_stream_4 {
        device_t dev;
        device_t child;
        struct bhnd_resource *r;
        bus_size_t offset;
        uint32_t *datap;
        bus_size_t count;
}

/** An implementation of bus_barrier() compatible with bhnd_resource */
METHOD void barrier {
        device_t dev;
        device_t child;
        struct bhnd_resource *r;
        bus_size_t offset;
        bus_size_t length;
        int flags;
}