linux-imx

// SPDX-License-Identifier: GPL-2.0

/*

 * Thunderbolt driver - capabilities lookup

 *

 * Copyright (c) 2014 Andreas Noever <andreas.noever@gmail.com>

 * Copyright (C) 2018, Intel Corporation

 */

​

#include <linux/slab.h>

#include <linux/errno.h>

​

#include "tb.h"

​

#define CAP_OFFSET_MAX      0xff

#define VSE_CAP_OFFSET_MAX  0xffff

​

struct tb_cap_any {

    union {

        struct tb_cap_basic basic;

        struct tb_cap_extended_short extended_short;

        struct tb_cap_extended_long extended_long;

    };

} __packed;

​

/**

 * tb_port_find_cap() - Find port capability

 * @port: Port to find the capability for

 * @cap: Capability to look

 *

 * Returns offset to start of capability or %-ENOENT if no such

 * capability was found. Negative errno is returned if there was an

 * error.

 */

int tb_port_find_cap(struct tb_port *port, enum tb_port_cap cap)

{

    u32 offset;

​

    /*

     * DP out adapters claim to implement TMU capability but in

     * reality they do not so we hard code the adapter specific

     * capability offset here.

     */

    if (port->config.type == TB_TYPE_DP_HDMI_OUT)

        offset = 0x39;

    else

        offset = 0x1;

​

    do {

        struct tb_cap_any header;

        int ret;

​

        ret = tb_port_read(port, &header, TB_CFG_PORT, offset, 1);

        if (ret)

            return ret;

​

        if (header.basic.cap == cap)

            return offset;

​

        offset = header.basic.next;

    } while (offset);

​

    return -ENOENT;

}