/*
* Copyright (c) 2012 Sebastian Huber. All rights reserved.
*
* The license and distribution terms for this file may be
* found in the file LICENSE in this distribution or at
* http://www.rtems.org/license/LICENSE.
*/
#include <libchip/sersupp.h>
#include <bsp.h>
#include <bsp/io.h>
#include <bsp/rcc.h>
#include <bsp/irq.h>
#include <bsp/usart.h>
#include <bsp/stm32f4.h>
#include <termios.h>
#include <string.h>
static volatile stm32f4_usart *usart_get_regs(const console_tbl *ct)
{
return (stm32f4_usart *) ct->ulCtrlPort1;
}
#if 0
static rtems_vector_number usart_get_irq_number(const console_tbl *ct)
{
return ct->ulIntVector;
}
#endif
#ifdef BSP_CONSOLE_USE_INTERRUPTS
/**
* Read characters in an interrupt
*/
static void stm32f4_usart_interrupt(void *arg)
{
rtems_termios_tty *tty = (rtems_termios_tty *) arg;
const console_tbl *ct = Console_Port_Tbl [tty->minor];
volatile stm32f4_usart *usart = usart_get_regs(ct);
while ((usart->sr & STM32F4_USART_SR_RXNE) == STM32F4_USART_SR_RXNE)
{
char data = STM32F4_USART_DR_GET(usart->dr);
rtems_termios_enqueue_raw_characters(tty, &data, sizeof(data));
}
}
#endif
static const stm32f4_rcc_index usart_rcc_index [] = {
STM32F4_RCC_USART1,
STM32F4_RCC_USART2,
STM32F4_RCC_USART3,
STM32F4_RCC_UART4,
STM32F4_RCC_UART5,
#ifdef STM32F4_FAMILY_F4XXXX
STM32F4_RCC_USART6
#endif /* STM32F4_FAMILY_F4XXXX */
};
static stm32f4_rcc_index usart_get_rcc_index(const console_tbl *ct)
{
return usart_rcc_index [ct->ulCtrlPort2];
}
static const uint8_t usart_pclk_index [] = { 1, 0, 0, 0, 0, 1 };
static const uint32_t usart_pclk_by_index [] = {
STM32F4_PCLK1,
STM32F4_PCLK2
};
static uint32_t usart_get_pclk(const console_tbl *ct)
{
return usart_pclk_by_index [usart_pclk_index [ct->ulCtrlPort2]];
}
static uint32_t usart_get_baud(const console_tbl *ct)
{
return ct->ulClock;
}
/*
* a = 8 * (2 - CR1[OVER8])
*
* usartdiv = div_mantissa + div_fraction / a
*
* baud = pclk / (a * usartdiv)
*
* usartdiv = pclk / (a * baud)
*
* Calculation in integer arithmetic:
*
* 1. div_mantissa = pclk / (a * baud)
*
* 2. div_fraction = pclk / (baud - a * div_mantissa)
*/
static uint32_t usart_get_bbr(
volatile stm32f4_usart *usart,
uint32_t pclk,
uint32_t baud
)
{
uint32_t a = 8 * (2 - ((usart->cr1 & STM32F4_USART_CR1_OVER8) != 0));
uint32_t div_mantissa_low = pclk / (a * baud);
uint32_t div_fraction_low = pclk / (baud - a * div_mantissa_low);
uint32_t div_mantissa_high;
uint32_t div_fraction_high;
uint32_t high_err;
uint32_t low_err;
uint32_t div_mantissa;
uint32_t div_fraction;
if (div_fraction_low < a - 1) {
div_mantissa_high = div_fraction_low;
div_fraction_high = div_fraction_low + 1;
} else {
div_mantissa_high = div_fraction_low + 1;
div_fraction_high = 0;
}
high_err = pclk - baud * (a * div_mantissa_high + div_fraction_high);
low_err = baud * (a * div_mantissa_low + div_fraction_low) - pclk;
if (low_err < high_err) {
div_mantissa = div_mantissa_low;
div_fraction = div_fraction_low;
} else {
div_mantissa = div_mantissa_high;
div_fraction = div_fraction_high;
}
return STM32F4_USART_BBR_DIV_MANTISSA(div_mantissa)
| STM32F4_USART_BBR_DIV_FRACTION(div_fraction);
}
static void usart_initialize(int minor)
{
const console_tbl *ct = Console_Port_Tbl [minor];
volatile stm32f4_usart *usart = usart_get_regs(ct);
uint32_t pclk = usart_get_pclk(ct);
uint32_t baud = usart_get_baud(ct);
stm32f4_rcc_index rcc_index = usart_get_rcc_index(ct);
stm32f4_rcc_set_clock(rcc_index, true);
usart->cr1 = 0;
usart->cr2 = 0;
usart->cr3 = 0;
usart->bbr = usart_get_bbr(usart, pclk, baud);
usart->cr1 = STM32F4_USART_CR1_UE // UART enable
#ifdef BSP_CONSOLE_USE_INTERRUPTS
| STM32F4_USART_CR1_RXNEIE // RX interrupt
#endif
| STM32F4_USART_CR1_TE // TX enable
| STM32F4_USART_CR1_RE; // RX enable
}
static int usart_first_open(int major, int minor, void *arg)
{
rtems_status_code sc = RTEMS_SUCCESSFUL;
rtems_libio_open_close_args_t *oc = (rtems_libio_open_close_args_t *) arg;
rtems_termios_tty *tty = (struct rtems_termios_tty *) oc->iop->data1;
const console_tbl *ct = Console_Port_Tbl [minor];
console_data *cd = &Console_Port_Data [minor];
cd->termios_data = tty;
rtems_termios_set_initial_baud(tty, ct->ulClock);
#ifdef BSP_CONSOLE_USE_INTERRUPTS
sc = rtems_interrupt_handler_install(ct->ulIntVector,
ct->sDeviceName,
RTEMS_INTERRUPT_UNIQUE,
stm32f4_usart_interrupt,
tty);
#endif
return sc;
}
static int usart_last_close(int major, int minor, void *arg)
{
rtems_status_code sc = RTEMS_SUCCESSFUL;
#ifdef BSP_CONSOLE_USE_INTERRUPTS
rtems_libio_open_close_args_t *oc = (rtems_libio_open_close_args_t *) arg;
rtems_termios_tty *tty = (struct rtems_termios_tty *) oc->iop->data1;
const console_tbl *ct = Console_Port_Tbl [minor];
sc = rtems_interrupt_handler_remove(ct->ulIntVector, stm32f4_usart_interrupt, tty);
#endif
return sc;
}
#ifndef BSP_CONSOLE_USE_INTERRUPTS
static int usart_read_polled(int minor)
{
const console_tbl *ct = Console_Port_Tbl [minor];
volatile stm32f4_usart *usart = usart_get_regs(ct);
if ((usart->sr & STM32F4_USART_SR_RXNE) != 0) {
return STM32F4_USART_DR_GET(usart->dr);
} else {
return -1;
}
}
#endif
static void usart_write_polled(int minor, char c)
{
const console_tbl *ct = Console_Port_Tbl [minor];
volatile stm32f4_usart *usart = usart_get_regs(ct);
while ((usart->sr & STM32F4_USART_SR_TXE) == 0) {
/* Wait */
}
usart->dr = STM32F4_USART_DR(c);
}
static ssize_t usart_write_support_polled(
int minor,
const char *s,
size_t n
)
{
ssize_t i = 0;
for (i = 0; i < n; ++i) {
usart_write_polled(minor, s [i]);
}
return n;
}
/**
* Configure settings from a termios call to tcsetattr()
*/
static int usart_set_attributes(int minor, const struct termios *term)
{
console_tbl *ct = Console_Port_Tbl[minor];
volatile stm32f4_usart *usart = usart_get_regs(ct);
uint32_t pclk = usart_get_pclk(ct);
uint32_t baud = term->c_ispeed;
ct->ulClock = baud;
usart->bbr = usart_get_bbr(usart, pclk, baud);
return 0;
}
const console_fns stm32f4_usart_fns = {
.deviceProbe = libchip_serial_default_probe,
.deviceFirstOpen = usart_first_open,
.deviceLastClose = usart_last_close,
#ifdef BSP_CONSOLE_USE_INTERRUPTS
.deviceRead = NULL,
#else
.deviceRead = usart_read_polled,
#endif
.deviceWrite = usart_write_support_polled,
.deviceInitialize = usart_initialize,
.deviceWritePolled = usart_write_polled,
.deviceSetAttributes = usart_set_attributes,
.deviceOutputUsesInterrupts = false
};