// 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 #define TMU_ACCESS_EN BIT(20) 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; 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); } } static int __tb_port_find_cap(struct tb_port *port, enum tb_port_cap cap) { u32 offset = 1; 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; } /** * 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_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 = sw->config.first_cap_offset; while (offset > 0 && offset < CAP_OFFSET_MAX) { struct tb_cap_any header; int ret; ret = tb_sw_read(sw, &header, TB_CFG_SWITCH, offset, 1); if (ret) return ret; if (header.basic.cap == cap) return offset; offset = header.basic.next; } 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) { struct tb_cap_any header; int offset; offset = tb_switch_find_cap(sw, TB_SWITCH_CAP_VSE); if (offset < 0) return offset; while (offset > 0 && offset < VSE_CAP_OFFSET_MAX) { int ret; ret = tb_sw_read(sw, &header, TB_CFG_SWITCH, offset, 2); if (ret) return ret; /* * Extended vendor specific capabilities come in two * flavors: short and long. The latter is used when * offset is over 0xff. */ if (offset >= CAP_OFFSET_MAX) { if (header.extended_long.vsec_id == vsec) return offset; offset = header.extended_long.next; } else { if (header.extended_short.vsec_id == vsec) return offset; if (!header.extended_short.length) return -ENOENT; offset = header.extended_short.next; } } return -ENOENT; }