genode/base/include/drivers/uart/tl16c750_base.h
2012-05-29 13:54:58 +02:00

226 lines
5.6 KiB
C++

/*
* \brief Base UART driver for the Texas instruments TL16C750 module
* \author Martin stein
* \date 2011-10-17
*/
/*
* Copyright (C) 2011-2012 Genode Labs GmbH
*
* This file is part of the Genode OS framework, which is distributed
* under the terms of the GNU General Public License version 2.
*/
#ifndef _BASE__INCLUDE__DRIVERS__UART__TL16C750_BASE_H_
#define _BASE__INCLUDE__DRIVERS__UART__TL16C750_BASE_H_
/* Genode includes */
#include <util/mmio.h>
namespace Genode
{
enum {
ASCII_LINE_FEED = 10,
ASCII_CARRIAGE_RETURN = 13,
};
/**
* Base driver Texas instruments TL16C750 UART module
*
* \detail In contrast to the abilities of the TL16C750, this driver
* targets only the basic UART functionalities.
*/
class Tl16c750_base : public Mmio
{
/**
* Least significant divisor part
*/
struct Uart_dll : Register<0x0, 32>
{
struct Clock_lsb : Bitfield<0, 8> { };
};
/**
* Transmit holding register
*/
struct Uart_thr : Register<0x0, 32>
{
struct Thr : Bitfield<0, 8> { };
};
/**
* Most significant divisor part
*/
struct Uart_dlh : Register<0x4, 32>
{
struct Clock_msb : Bitfield<0, 6> { };
};
/**
* Interrupt enable register
*/
struct Uart_ier : Register<0x4, 32>
{
struct Rhr_it : Bitfield<0, 1> { };
struct Thr_it : Bitfield<1, 1> { };
struct Line_sts_it : Bitfield<2, 1> { };
struct Modem_sts_it : Bitfield<3, 1> { };
struct Sleep_mode : Bitfield<4, 1> { };
struct Xoff_it : Bitfield<5, 1> { };
struct Rts_it : Bitfield<6, 1> { };
struct Cts_it : Bitfield<7, 1> { };
};
/**
* FIFO control register
*/
struct Uart_fcr : Register<0x8, 32>
{
struct Fifo_enable : Bitfield<0, 1> { };
};
/**
* Line control register
*/
struct Uart_lcr : Register<0xc, 32>
{
struct Char_length : Bitfield<0, 2>
{
enum { _8_BIT = 3 };
};
struct Nb_stop : Bitfield<2, 1>
{
enum { _1_STOP_BIT = 0 };
};
struct Parity_en : Bitfield<3, 1> { };
struct Break_en : Bitfield<6, 1> { };
struct Div_en : Bitfield<7, 1> { };
struct Reg_mode : Bitfield<0, 8>
{
enum { OPERATIONAL = 0, CONFIG_A = 0x80, CONFIG_B = 0xbf };
};
};
/**
* Modem control register
*/
struct Uart_mcr : Register<0x10, 32>
{
struct Tcr_tlr : Bitfield<6, 1> { };
};
/**
* Line status register
*/
struct Uart_lsr : Register<0x14, 32>
{
struct Tx_fifo_empty : Bitfield<5, 1> { };
};
/**
* Mode definition register 1
*/
struct Uart_mdr1 : Register<0x20, 32>
{
struct Mode_select : Bitfield<0, 3>
{
enum { UART_16X = 0, DISABLED = 7 };
};
};
/**
* System control register
*/
struct Uart_sysc : Register<0x54, 32>
{
struct Softreset : Bitfield<1, 1> { };
};
/**
* System status register
*/
struct Uart_syss : Register<0x58, 32>
{
struct Resetdone : Bitfield<0, 1> { };
};
public:
/**
* Constructor
*
* \param base MMIO base address
* \param clock Reference clock
* \param baud_rate Targeted baud rate
*/
Tl16c750_base(addr_t const base, unsigned long const clock,
unsigned long const baud_rate) : Mmio(base)
{
/* Reset and disable UART */
write<Uart_sysc::Softreset>(1);
while (!read<Uart_syss::Resetdone>()) ;
write<Uart_mdr1::Mode_select>(Uart_mdr1::Mode_select::DISABLED);
/* Enable access to 'Uart_fcr' and 'Uart_ier' */
write<Uart_lcr::Reg_mode>(Uart_lcr::Reg_mode::OPERATIONAL);
/* Configure FIFOs, we don't use any interrupts or DMA,
* thus FIFO trigger and DMA configurations are dispensable */
write<Uart_fcr::Fifo_enable>(1);
/* Disable interrupts and sleep mode */
write<Uart_ier>(Uart_ier::Rhr_it::bits(0)
| Uart_ier::Thr_it::bits(0)
| Uart_ier::Line_sts_it::bits(0)
| Uart_ier::Modem_sts_it::bits(0)
| Uart_ier::Sleep_mode::bits(0)
| Uart_ier::Xoff_it::bits(0)
| Uart_ier::Rts_it::bits(0)
| Uart_ier::Cts_it::bits(0));
/* Enable access to 'Uart_dlh' and 'Uart_dll' */
write<Uart_lcr::Reg_mode>(Uart_lcr::Reg_mode::CONFIG_B);
/* Load the new divisor value (this driver solely uses
* 'UART_16X' mode )*/
enum { UART_16X_DIVIDER_LOG2 = 4 };
unsigned long const adjusted_br = baud_rate << UART_16X_DIVIDER_LOG2;
double const divisor = (double)clock / adjusted_br;
unsigned long const divisor_uint = (unsigned long)divisor;
write<Uart_dll::Clock_lsb>(divisor_uint);
write<Uart_dlh::Clock_msb>(divisor_uint>>Uart_dll::Clock_lsb::WIDTH);
/* Configure protocol formatting and thereby return to
* operational mode */
write<Uart_lcr>(Uart_lcr::Char_length::bits(Uart_lcr::Char_length::_8_BIT)
| Uart_lcr::Nb_stop::bits(Uart_lcr::Nb_stop::_1_STOP_BIT)
| Uart_lcr::Parity_en::bits(0)
| Uart_lcr::Break_en::bits(0)
| Uart_lcr::Div_en::bits(0));
/* Switch to UART mode, we don't use hardware or software flow
* control, thus according configurations are dispensable*/
write<Uart_mdr1::Mode_select>(Uart_mdr1::Mode_select::UART_16X);
}
/**
* Transmit ASCII char 'c'
*/
void put_char(char const c)
{
/* Wait as long as the transmission buffer is full */
while (!read<Uart_lsr::Tx_fifo_empty>()) ;
/* Auto complete new line commands */
if (c == ASCII_LINE_FEED)
write<Uart_thr::Thr>(ASCII_CARRIAGE_RETURN);
/* Transmit character */
write<Uart_thr::Thr>(c);
}
};
}
#endif /* _BASE__INCLUDE__DRIVERS__UART__TL16C750_BASE_H_ */