153 lines
3.9 KiB
C
153 lines
3.9 KiB
C
/* Copyright 2012 The Chromium OS Authors. All rights reserved.
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* Use of this source code is governed by a BSD-style license that can be
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* found in the LICENSE file.
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*/
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/* PECI interface for Chrome EC */
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#include "chipset.h"
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#include "clock.h"
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#include "common.h"
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#include "console.h"
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#include "gpio.h"
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#include "hooks.h"
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#include "peci.h"
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#include "registers.h"
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#include "temp_sensor.h"
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#include "util.h"
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/* Initial PECI baud rate */
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#define PECI_BAUD_RATE 100000
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/* Polling interval for PECI, in ms */
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#define PECI_POLL_INTERVAL_MS 250
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/*
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* Internal and external path delays, in ns. The external delay is a
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* best-guess measurement, but we're fairly tolerant of a bad guess because
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* PECI_BAUD_RATE is slow compared to PECI's actual maximum baud rate.
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*/
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#define PECI_TD_FET_NS 60
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#define PECI_TD_INT_NS 80
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/* Number of controller retries. Should be between 0 and 7. */
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#define PECI_RETRY_COUNT 4
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/* Timing negotiation error bypass. 1 = on. 0 = off. */
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#define PECI_ERROR_BYPASS 1
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#define TEMP_AVG_LENGTH 4 /* Should be power of 2 */
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static int temp_vals[TEMP_AVG_LENGTH];
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static int temp_idx;
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int peci_get_cpu_temp(void)
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{
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int v = LM4_PECI_M0D0 & 0xffff;
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if (v >= 0x8000 && v <= 0x8fff)
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return -1;
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return v >> 6;
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}
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int peci_temp_sensor_get_val(int idx, int *temp_ptr)
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{
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int sum = 0;
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int success_cnt = 0;
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int i;
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if (!chipset_in_state(CHIPSET_STATE_ON))
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return EC_ERROR_NOT_POWERED;
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for (i = 0; i < TEMP_AVG_LENGTH; ++i) {
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if (temp_vals[i] >= 0) {
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success_cnt++;
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sum += temp_vals[i];
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}
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}
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/*
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* Require at least two valid samples. When the AP transitions into S0,
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* it is possible, depending on the timing of the PECI sample, to read
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* an invalid temperature. This is very rare, but when it does happen
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* the temperature returned is CONFIG_PECI_TJMAX. Requiring two valid
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* samples here assures us that one bad maximum temperature reading
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* when entering S0 won't cause us to trigger an over temperature.
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*/
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if (success_cnt < 2)
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return EC_ERROR_UNKNOWN;
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*temp_ptr = sum / success_cnt;
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return EC_SUCCESS;
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}
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static void peci_temp_sensor_poll(void)
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{
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temp_vals[temp_idx] = peci_get_cpu_temp();
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temp_idx = (temp_idx + 1) & (TEMP_AVG_LENGTH - 1);
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}
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DECLARE_HOOK(HOOK_TICK, peci_temp_sensor_poll, HOOK_PRIO_TEMP_SENSOR);
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static void peci_freq_changed(void)
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{
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int freq = clock_get_freq();
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int baud;
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/* Disable polling while reconfiguring */
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LM4_PECI_CTL = 0;
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/*
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* Calculate baud setting from desired rate, compensating for internal
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* and external delays.
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*/
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baud = freq / (4 * PECI_BAUD_RATE) - 2;
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baud -= (freq / 1000000) * (PECI_TD_FET_NS + PECI_TD_INT_NS) / 1000;
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/* Set baud rate and polling rate */
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LM4_PECI_DIV = (baud << 16) |
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(PECI_POLL_INTERVAL_MS * (freq / 1000 / 4096));
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/* Set up temperature monitoring to report in degrees K */
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LM4_PECI_CTL = ((CONFIG_PECI_TJMAX + 273) << 22) | 0x0001 |
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(PECI_RETRY_COUNT << 12) |
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(PECI_ERROR_BYPASS << 11);
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}
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DECLARE_HOOK(HOOK_FREQ_CHANGE, peci_freq_changed, HOOK_PRIO_DEFAULT);
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static void peci_init(void)
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{
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int i;
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/* Enable the PECI module in run and sleep modes. */
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clock_enable_peripheral(CGC_OFFSET_PECI, 0x1,
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CGC_MODE_RUN | CGC_MODE_SLEEP);
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/* Configure GPIOs */
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gpio_config_module(MODULE_PECI, 1);
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/* Set initial clock frequency */
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peci_freq_changed();
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/* Initialize temperature reading buffer to a sane value. */
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for (i = 0; i < TEMP_AVG_LENGTH; ++i)
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temp_vals[i] = 300; /* 27 C */
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}
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DECLARE_HOOK(HOOK_INIT, peci_init, HOOK_PRIO_DEFAULT);
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/*****************************************************************************/
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/* Console commands */
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static int command_peci_temp(int argc, char **argv)
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{
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int t = peci_get_cpu_temp();
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if (t == -1) {
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ccprintf("PECI error 0x%04x\n", LM4_PECI_M0D0 & 0xffff);
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return EC_ERROR_UNKNOWN;
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}
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ccprintf("CPU temp = %d K = %d C\n", t, K_TO_C(t));
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return EC_SUCCESS;
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}
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DECLARE_CONSOLE_COMMAND(pecitemp, command_peci_temp,
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NULL,
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"Print CPU temperature");
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