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/* Copyright (c) 2012 The Chromium OS Authors. All rights reserved.
* Use of this source code is governed by a BSD-style license that can be
* found in the LICENSE file.
*/
/* PECI interface for Chrome EC */
#include "board.h"
#include "console.h"
#include "gpio.h"
#include "peci.h"
#include "registers.h"
#include "temp_sensor.h"
#include "uart.h"
#include "util.h"
/* Max junction temperature for processor in degrees C */
/* TODO: read TjMax from processor via PECI */
#define PECI_TJMAX 105
/* Initial PECI baud rate */
#define PECI_BAUD_RATE 150000
/* Polling interval for PECI, in ms */
#define PECI_POLL_INTERVAL_MS 200
/* Internal and external path delays, in ns */
#define PECI_TD_FET_NS 25 /* Guess; TODO: what is real delay */
#define PECI_TD_INT_NS 80
static int last_temp_val;
/* Configures the GPIOs for the PECI module. */
static void configure_gpios(void)
{
/* PJ6 alternate function 1 = PECI Tx */
gpio_set_alternate_function(LM4_GPIO_J, 0x40, 1);
/* PJ7 analog input = PECI Rx (comparator) */
LM4_GPIO_DEN(LM4_GPIO_J) &= ~0x80;
}
int peci_get_cpu_temp(void)
{
int v = LM4_PECI_M0D0 & 0xffff;
if (v >= 0x8000 && v <= 0x8fff)
return -1;
return v >> 6;
}
int peci_temp_sensor_poll(void)
{
last_temp_val = peci_get_cpu_temp();
if (last_temp_val > 0)
return EC_SUCCESS;
else
return EC_ERROR_UNKNOWN;
}
int peci_temp_sensor_get_val(int idx)
{
return last_temp_val;
}
/*****************************************************************************/
/* Console commands */
static int command_peci_temp(int argc, char **argv)
{
int t = peci_get_cpu_temp();
if (t == -1) {
uart_puts("Error reading CPU temperature via PECI\n");
uart_printf("Error code = 0x%04x\n", LM4_PECI_M0D0 & 0xffff);
return EC_ERROR_UNKNOWN;
}
uart_printf("Current CPU temperature = %d K = %d C\n", t, t - 273);
return EC_SUCCESS;
}
DECLARE_CONSOLE_COMMAND(pecitemp, command_peci_temp);
/*****************************************************************************/
/* Initialization */
int peci_init(void)
{
volatile uint32_t scratch __attribute__((unused));
int baud;
/* Enable the PECI module and delay a few clocks */
LM4_SYSTEM_RCGCPECI = 1;
scratch = LM4_SYSTEM_RCGCPECI;
/* Configure GPIOs */
configure_gpios();
/* Calculate baud setting from desired rate, compensating for internal
* and external delays. */
baud = CPU_CLOCK / (4 * PECI_BAUD_RATE) - 2;
baud -= (CPU_CLOCK / 1000000) * (PECI_TD_FET_NS + PECI_TD_INT_NS)
/ 1000;
/* Set baud rate and polling rate */
LM4_PECI_DIV = (baud << 16) |
(PECI_POLL_INTERVAL_MS * (CPU_CLOCK / 1000 / 4096));
/* Set up temperature monitoring to report in degrees K */
LM4_PECI_CTL = ((PECI_TJMAX + 273) << 22) | 0x2001;
return EC_SUCCESS;
}
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