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- // SPDX-License-Identifier: GPL-2.0
- /*
- * Thunderbolt driver - capabilities lookup
- *
- * Copyright (c) 2014 Andreas Noever <[email protected]>
- * 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
- #define TMU_ACCESS_EN BIT(20)
- static int tb_port_enable_tmu(struct tb_port *port, bool enable)
- {
- struct tb_switch *sw = port->sw;
- u32 value, offset;
- int ret;
- /*
- * Legacy devices need to have TMU access enabled before port
- * space can be fully accessed.
- */
- if (tb_switch_is_light_ridge(sw))
- offset = 0x26;
- else if (tb_switch_is_eagle_ridge(sw))
- offset = 0x2a;
- else
- return 0;
- ret = tb_sw_read(sw, &value, TB_CFG_SWITCH, offset, 1);
- if (ret)
- return ret;
- if (enable)
- value |= TMU_ACCESS_EN;
- else
- value &= ~TMU_ACCESS_EN;
- return tb_sw_write(sw, &value, TB_CFG_SWITCH, offset, 1);
- }
- static void tb_port_dummy_read(struct tb_port *port)
- {
- /*
- * When reading from next capability pointer location in port
- * config space the read data is not cleared on LR. To avoid
- * reading stale data on next read perform one dummy read after
- * port capabilities are walked.
- */
- if (tb_switch_is_light_ridge(port->sw)) {
- u32 dummy;
- tb_port_read(port, &dummy, TB_CFG_PORT, 0, 1);
- }
- }
- /**
- * tb_port_next_cap() - Return next capability in the linked list
- * @port: Port to find the capability for
- * @offset: Previous capability offset (%0 for start)
- *
- * Returns dword offset of the next capability in port config space
- * capability list and returns it. Passing %0 returns the first entry in
- * the capability list. If no next capability is found returns %0. In case
- * of failure returns negative errno.
- */
- int tb_port_next_cap(struct tb_port *port, unsigned int offset)
- {
- struct tb_cap_any header;
- int ret;
- if (!offset)
- return port->config.first_cap_offset;
- ret = tb_port_read(port, &header, TB_CFG_PORT, offset, 1);
- if (ret)
- return ret;
- return header.basic.next;
- }
- static int __tb_port_find_cap(struct tb_port *port, enum tb_port_cap cap)
- {
- int offset = 0;
- do {
- struct tb_cap_any header;
- int ret;
- offset = tb_port_next_cap(port, offset);
- if (offset < 0)
- return offset;
- ret = tb_port_read(port, &header, TB_CFG_PORT, offset, 1);
- if (ret)
- return ret;
- if (header.basic.cap == cap)
- return offset;
- } while (offset > 0);
- return -ENOENT;
- }
- /**
- * 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)
- {
- int ret;
- ret = tb_port_enable_tmu(port, true);
- if (ret)
- return ret;
- ret = __tb_port_find_cap(port, cap);
- tb_port_dummy_read(port);
- tb_port_enable_tmu(port, false);
- return ret;
- }
- /**
- * tb_switch_next_cap() - Return next capability in the linked list
- * @sw: Switch to find the capability for
- * @offset: Previous capability offset (%0 for start)
- *
- * Finds dword offset of the next capability in router config space
- * capability list and returns it. Passing %0 returns the first entry in
- * the capability list. If no next capability is found returns %0. In case
- * of failure returns negative errno.
- */
- int tb_switch_next_cap(struct tb_switch *sw, unsigned int offset)
- {
- struct tb_cap_any header;
- int ret;
- if (!offset)
- return sw->config.first_cap_offset;
- ret = tb_sw_read(sw, &header, TB_CFG_SWITCH, offset, 2);
- if (ret)
- return ret;
- switch (header.basic.cap) {
- case TB_SWITCH_CAP_TMU:
- ret = header.basic.next;
- break;
- case TB_SWITCH_CAP_VSE:
- if (!header.extended_short.length)
- ret = header.extended_long.next;
- else
- ret = header.extended_short.next;
- break;
- default:
- tb_sw_dbg(sw, "unknown capability %#x at %#x\n",
- header.basic.cap, offset);
- ret = -EINVAL;
- break;
- }
- return ret >= VSE_CAP_OFFSET_MAX ? 0 : ret;
- }
- /**
- * tb_switch_find_cap() - Find switch capability
- * @sw: Switch 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_switch_find_cap(struct tb_switch *sw, enum tb_switch_cap cap)
- {
- int offset = 0;
- do {
- struct tb_cap_any header;
- int ret;
- offset = tb_switch_next_cap(sw, offset);
- if (offset < 0)
- return offset;
- ret = tb_sw_read(sw, &header, TB_CFG_SWITCH, offset, 1);
- if (ret)
- return ret;
- if (header.basic.cap == cap)
- return offset;
- } while (offset);
- return -ENOENT;
- }
- /**
- * tb_switch_find_vse_cap() - Find switch vendor specific capability
- * @sw: Switch to find the capability for
- * @vsec: Vendor specific capability to look
- *
- * Functions enumerates vendor specific capabilities (VSEC) of a switch
- * and returns offset when capability matching @vsec is found. If no
- * such capability is found returns %-ENOENT. In case of error returns
- * negative errno.
- */
- int tb_switch_find_vse_cap(struct tb_switch *sw, enum tb_switch_vse_cap vsec)
- {
- int offset = 0;
- do {
- struct tb_cap_any header;
- int ret;
- offset = tb_switch_next_cap(sw, offset);
- if (offset < 0)
- return offset;
- ret = tb_sw_read(sw, &header, TB_CFG_SWITCH, offset, 1);
- if (ret)
- return ret;
- if (header.extended_short.cap == TB_SWITCH_CAP_VSE &&
- header.extended_short.vsec_id == vsec)
- return offset;
- } while (offset);
- return -ENOENT;
- }
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