diff options
Diffstat (limited to 'smc.c')
| -rw-r--r-- | smc.c | 156 |
1 files changed, 156 insertions, 0 deletions
@@ -0,0 +1,156 @@ +/* + * This file is part of the coreboot project. + * + * Copyright (C) 2019 Evgeny Zinoviev <me@ch1p.io> + * + * SMC interacting code is based on applesmc linux driver by: + * Copyright (C) 2007 Nicolas Boichat <nicolas@boichat.ch> + * Copyright (C) 2010 Henrik Rydberg <rydberg@euromail.se> + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation; version 2 of the License. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + */ + +#include <stdlib.h> +#include <sys/io.h> +#include <errno.h> +#include <stdio.h> +#include "smc.h" + +/* + * wait_read - Wait for a byte to appear on SMC port. Callers must + * hold applesmc_lock. + */ +int wait_read(void) +{ + uint8_t status; + int us; + for (us = APPLESMC_MIN_WAIT; us < APPLESMC_MAX_WAIT; us <<= 1) { + usleep(us); + status = inb(APPLESMC_CMD_PORT); + + /* read: wait for smc to settle */ + if (status & 0x01) + return 0; + } + + fprintf(stderr, "%s() fail: 0x%02x\n", __func__, status); + return -EIO; +} + +/* + * send_byte - Write to SMC port, retrying when necessary. Callers + * must hold applesmc_lock. + */ +int send_byte(uint8_t cmd, uint16_t port) +{ + uint8_t status; + int us; + + outb(cmd, port); + for (us = APPLESMC_MIN_WAIT; us < APPLESMC_MAX_WAIT; us <<= 1) { + usleep(us); + status = inb(APPLESMC_CMD_PORT); + /* write: wait for smc to settle */ + if (status & 0x02) + continue; + /* ready: cmd accepted, return */ + if (status & 0x04) + return 0; + /* timeout: give up */ + if (us << 1 == APPLESMC_MAX_WAIT) + break; + /* busy: long wait and resend */ + usleep(APPLESMC_RETRY_WAIT); + outb(cmd, port); + } + + fprintf(stderr, "%s(0x%02x, 0x%04x) fail: 0x%02x\n", + __func__, cmd, port, status); + return -EIO; +} + +int send_command(uint8_t cmd) +{ + return send_byte(cmd, APPLESMC_CMD_PORT); +} + +int send_argument(const char *key) +{ + int i; + + for (i = 0; i < 4; i++) + if (send_byte(key[i], APPLESMC_DATA_PORT)) + return -EIO; + return 0; +} + +int read_smc(uint8_t cmd, const char *key, uint8_t *buffer, uint8_t len) +{ + uint8_t status, data = 0; + int i; + + if (send_command(cmd) || send_argument(key)) { + fprintf(stderr, "%.4s: read arg fail\n", key); + return -EIO; + } + + /* This has no effect on newer (2012) SMCs */ + if (send_byte(len, APPLESMC_DATA_PORT)) { + fprintf(stderr, "%.4s: read len fail\n", key); + return -EIO; + } + + for (i = 0; i < len; i++) { + if (wait_read()) { + fprintf(stderr, "%.4s: read data[%d] fail\n", key, i); + return -EIO; + } + buffer[i] = inb(APPLESMC_DATA_PORT); + } + + /* Read the data port until bit0 is cleared */ + for (i = 0; i < 16; i++) { + usleep(APPLESMC_MIN_WAIT); + status = inb(APPLESMC_CMD_PORT); + if (!(status & 0x01)) + break; + data = inb(APPLESMC_DATA_PORT); + } + + if (i) + fprintf(stderr, "flushed %d bytes, last value is: %d\n", + i, data); + + return 0; +} + +int write_smc(uint8_t cmd, const char *key, const uint8_t *buffer, uint8_t len) +{ + int i; + + if (send_command(cmd) || send_argument(key)) { + fprintf(stderr, "%s: write arg fail\n", key); + return -EIO; + } + + if (send_byte(len, APPLESMC_DATA_PORT)) { + fprintf(stderr, "%.4s: write len fail\n", key); + return -EIO; + } + + for (i = 0; i < len; i++) { + if (send_byte(buffer[i], APPLESMC_DATA_PORT)) { + fprintf(stderr, "%s: write data fail\n", key); + return -EIO; + } + } + + return 0; +} |