chip/it83xx/uart.c

/* Copyright 2013 The ChromiumOS Authors
 * Use of this source code is governed by a BSD-style license that can be
 * found in the LICENSE file.
 */

/* UART module for Chrome EC */

#include "clock.h"
#include "common.h"
#include "console.h"
#include "gpio.h"
#include "intc.h"
#include "registers.h"
#include "system.h"
#include "task.h"
#include "uart.h"
#include "util.h"

/* Traces on UART1 */
#define UART_PORT 0
#define UART_PORT_HOST 1

static int init_done;

int uart_init_done(void)
{
	return init_done;
}

void uart_tx_start(void)
{
	/* If interrupt is already enabled, nothing to do */
	if (IT83XX_UART_IER(UART_PORT) & 0x02)
		return;

	/* Do not allow deep sleep while transmit in progress */
	disable_sleep(SLEEP_MASK_UART);

	/* Re-enable the transmit interrupt. */
	IT83XX_UART_IER(UART_PORT) |= 0x02;
}

void uart_tx_stop(void)
{
	IT83XX_UART_IER(UART_PORT) &= ~0x02;

	/* Re-allow deep sleep */
	enable_sleep(SLEEP_MASK_UART);
}

void uart_tx_flush(void)
{
	/*
	 * Wait for transmit FIFO empty (TEMT) and transmitter holder
	 * register and transmitter shift registers to be empty (THRE).
	 */
	while ((IT83XX_UART_LSR(UART_PORT) & 0x60) != 0x60)
		;
}

int uart_tx_ready(void)
{
	/* Transmit is ready when FIFO is empty (THRE). */
	return IT83XX_UART_LSR(UART_PORT) & 0x20;
}

int uart_tx_in_progress(void)
{
	/*
	 * Transmit is in progress if transmit holding register or transmitter
	 * shift register are not empty (TEMT).
	 */
	return !(IT83XX_UART_LSR(UART_PORT) & 0x40);
}

int uart_rx_available(void)
{
	return IT83XX_UART_LSR(UART_PORT) & 0x01;
}

void uart_write_char(char c)
{
	/* Wait for space in transmit FIFO. */
	while (!uart_tx_ready())
		;

	IT83XX_UART_THR(UART_PORT) = c;
}

int uart_read_char(void)
{
	return IT83XX_UART_RBR(UART_PORT);
}

static void uart_ec_interrupt(void)
{
	uint8_t uart_ier;

	/* clear interrupt status */
	task_clear_pending_irq(IT83XX_IRQ_UART1);

	/* Read input FIFO until empty, then fill output FIFO */
	uart_process_input();
	uart_process_output();

	uart_ier = IT83XX_UART_IER(UART_PORT);
	IT83XX_UART_IER(UART_PORT) = 0;
	IT83XX_UART_IER(UART_PORT) = uart_ier;
}

static void intc_cpu_int_group_9(void)
{
	/* Determine interrupt number. */
	int intc_group_9 = intc_get_ec_int();

	switch (intc_group_9) {
	case IT83XX_IRQ_UART1:
		uart_ec_interrupt();
		break;
	default:
		break;
	}
}
DECLARE_IRQ(CPU_INT_GROUP_9, intc_cpu_int_group_9, 1);

static void uart_config(void)
{
	/*
	 * Specify clock source of the UART is 24MHz,
	 * must match CLK_UART_DIV_SEL.
	 */
	IT83XX_UART_CSSR(UART_PORT) = 0x01;

	/* 8-N-1 and DLAB set to allow access to DLL and DLM registers. */
	IT83XX_UART_LCR(UART_PORT) = 0x83;

	/* Set divisor to set baud rate to 115200 */
	IT83XX_UART_DLM(UART_PORT) = 0x00;
	IT83XX_UART_DLL(UART_PORT) = 0x01;

	/*
	 * Clear DLAB bit to exclude access to DLL and DLM and give access to
	 * RBR and THR.
	 */
	IT83XX_UART_LCR(UART_PORT) = 0x03;

	/*
	 * Enable TX and RX FIFOs and set RX FIFO interrupt level to the
	 * minimum 1 byte.
	 */
	IT83XX_UART_FCR(UART_PORT) = 0x07;

	/*
	 * set OUT2 bit to enable interrupt logic.
	 */
	IT83XX_UART_MCR(UART_PORT) = 0x08;
}

#ifdef CONFIG_UART_HOST
static void host_uart_config(void)
{
	/*
	 * Specify clock source of the UART is 24MHz,
	 * must match CLK_UART_DIV_SEL.
	 */
	IT83XX_UART_CSSR(UART_PORT_HOST) = 0x01;
	/* 8-N-1 and DLAB set to allow access to DLL and DLM registers. */
	IT83XX_UART_LCR(UART_PORT_HOST) = 0x83;
	/* Set divisor to set baud rate to 115200 */
	IT83XX_UART_DLM(UART_PORT_HOST) = 0x00;
	IT83XX_UART_DLL(UART_PORT_HOST) = 0x01;
	/*
	 * Clear DLAB bit to exclude access to DLL and DLM and give access to
	 * RBR and THR.
	 */
	IT83XX_UART_LCR(UART_PORT_HOST) = 0x03;
	/*
	 * Enable TX and RX FIFOs and set RX FIFO interrupt level to the
	 * minimum 1 byte.
	 */
	IT83XX_UART_FCR(UART_PORT_HOST) = 0x07;
}
#endif

#ifdef CONFIG_LOW_POWER_IDLE
void uart_enter_dsleep(void)
{
	gpio_clear_pending_interrupt(GPIO_UART1_RX);
	gpio_enable_interrupt(GPIO_UART1_RX);
}

void uart_exit_dsleep(void)
{
	gpio_disable_interrupt(GPIO_UART1_RX);
	gpio_clear_pending_interrupt(GPIO_UART1_RX);
}

void uart_deepsleep_interrupt(enum gpio_signal signal)
{
	clock_refresh_console_in_use();
	/* Disable interrupts on UART1 RX pin to avoid repeated interrupts. */
	gpio_disable_interrupt(GPIO_UART1_RX);
}
#endif /* CONFIG_LOW_POWER_IDLE */

void uart_init(void)
{
	/*
	 * bit3: uart1 belongs to the EC side.
	 * This is necessary for enabling eSPI module.
	 */
	IT83XX_GCTRL_RSTDMMC |= BIT(3);

	/* reset uart before config it */
	IT83XX_GCTRL_RSTC4 |= BIT(1);

	/* Waiting for when we can use the GPIO module to set pin muxing */
	gpio_config_module(MODULE_UART, 1);

	/* switch UART1 on without hardware flow control */
	IT83XX_GPIO_GRC1 |= 0x01;
	IT83XX_GPIO_GRC6 |= 0x03;

	/* Enable clocks to UART 1 and 2. */
	clock_enable_peripheral(CGC_OFFSET_UART, 0, 0);

	/* Config UART 1 */
	uart_config();

#ifdef CONFIG_UART_HOST
	/* bit2, reset UART2 */
	IT83XX_GCTRL_RSTC4 |= BIT(2);
	/* SIN1/SOUT1 of UART 2 is enabled. */
	IT83XX_GPIO_GRC1 |= BIT(2);
	/* Config UART 2 */
	host_uart_config();
#endif

	/* clear interrupt status */
	task_clear_pending_irq(IT83XX_IRQ_UART1);

	/* Enable interrupts */
	IT83XX_UART_IER(UART_PORT) = 0x03;
	task_enable_irq(IT83XX_IRQ_UART1);

	init_done = 1;
}