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x86: Add driver for MMIO-accessible 16X50 UART 

This patch adds a driver for an MMIO-accessible 16X50 UART.  It
assumes that the boot firmware assigned an MMIO range to the UART.  It
operates in polled mode with FIFOs enabled.
This commit is contained in:
Michael LeMay 2015-07-03 05:09:34 -07:00 committed by Jesus Sanchez-Palencia
parent c5f9cefac7
commit 6acdf50262
3 changed files with 168 additions and 1 deletions
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2
cpu/x86/Makefile.x86_quarkX1000
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@ -2,7 +2,7 @@ include $(CONTIKI)/cpu/x86/Makefile.x86_common
CONTIKI_CPU_DIRS += drivers/legacy_pc init/legacy_pc
CONTIKI_SOURCEFILES += bootstrap_quarkX1000.S rtc.c pit.c pic.c irq.c nmi.c pci.c
CONTIKI_SOURCEFILES += bootstrap_quarkX1000.S rtc.c pit.c pic.c irq.c nmi.c pci.c uart-16x50.c
CFLAGS += -m32 -march=i586 -mtune=i586
LDFLAGS += -m32 -T $(CONTIKI)/cpu/x86/quarkX1000.ld

123
cpu/x86/drivers/legacy_pc/uart-16x50.c Normal file
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@ -0,0 +1,123 @@
/*
* Copyright (C) 2015, Intel Corporation. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* 3. Neither the name of the copyright holder nor the names of its
* contributors may be used to endorse or promote products derived
* from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
* COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
* STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
* OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#include "uart-16x50.h"
#include <stdlib.h>
#include "helpers.h"
/* Refer to Intel Quark SoC X1000 Datasheet, Chapter 18 for more details on
* UART operation.
*/
/* Divisor Latch Access Bit (DLAB) mask for Line Control Register (LCR).
*
* When bit is set, enables access to divisor registers to set baud rate. When
* clear, enables access to other registers mapped to the same addresses as the
* divisor registers.
*/
#define UART_LCR_7_DLAB BIT(7)
/* Setting for LCR that configures the UART to operate with no parity, 1 stop
* bit, and eight bits per character.
*/
#define UART_LCR_8BITS 0x03
/* FIFO Control Register (FCR) bitmasks */
#define UART_FCR_0_FIFOE BIT(0) /*< enable FIFOs */
#define UART_FCR_1_RFIFOR BIT(1) /*< reset RX FIFO */
#define UART_FCR_2_XFIFOR BIT(2) /*< reset TX FIFO */
/* Line Status Register (LSR) Transmit Holding Register Empty bitmask to check
* whether the Transmit Holding Register (THR) or TX FIFO is empty.
*/
#define UART_LSR_5_THRE BIT(5)
/* MMIO registers for UART */
typedef struct uart_16x50_regs {
volatile uint32_t rbr_thr_dll, ier_dlh, iir_fcr, lcr;
volatile uint32_t mcr, lsr, msr, scr, usr, htx, dmasa;
} uart_16x50_regs_t;
/*---------------------------------------------------------------------------*/
/**
* \brief Initialize an MMIO-programmable 16X50 UART.
* \param c_this Structure that will be initialized to represent the device.
* \param pci_addr PCI address of device.
* \param dl Divisor setting to configure the baud rate.
*/
void
uart_16x50_init(uart_16x50_driver_t *c_this,
pci_config_addr_t pci_addr,
uint16_t dl)
{
/* This assumes that the UART had an MMIO range assigned to it by the
* firmware during boot.
*/
pci_init_bar0(c_this, pci_addr);
uart_16x50_regs_t *regs = (uart_16x50_regs_t *)c_this->mmio;
/* Set the DLAB bit to enable access to divisor settings. */
regs->lcr = UART_LCR_7_DLAB;
/* The divisor settings configure the baud rate, and may need to be defined
* on a per-device basis.
*/
regs->rbr_thr_dll = dl & UINT8_MAX;
regs->ier_dlh = dl >> 8;
/* Clear the DLAB bit to enable access to other settings and configure other
* UART parameters.
*/
regs->lcr = UART_LCR_8BITS;
/* Enable the FIFOs. */
regs->iir_fcr = UART_FCR_0_FIFOE | UART_FCR_1_RFIFOR | UART_FCR_2_XFIFOR;
}
/*---------------------------------------------------------------------------*/
/**
* \brief Transmit a character through a UART.
* \param c_this Initialized structure representing the device.
* \param c Character to be transmitted.
*
* This procedure will block indefinitely until the UART is ready
* to accept the character to be transmitted.
*/
void
uart_16x50_tx(uart_16x50_driver_t c_this, uint8_t c)
{
struct uart_16x50_regs *regs = (uart_16x50_regs_t *)c_this.mmio;
/* Wait for space in TX FIFO. */
while((regs->lsr & UART_LSR_5_THRE) == 0);
/* Add character to TX FIFO. */
regs->rbr_thr_dll = c;
}
/*---------------------------------------------------------------------------*/

44
cpu/x86/drivers/legacy_pc/uart-16x50.h Normal file
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@ -0,0 +1,44 @@
/*
* Copyright (C) 2015, Intel Corporation. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* 3. Neither the name of the copyright holder nor the names of its
* contributors may be used to endorse or promote products derived
* from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
* COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
* STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
* OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#ifndef CPU_X86_DRIVERS_LEGACY_PC_UART_16X50_H_
#define CPU_X86_DRIVERS_LEGACY_PC_UART_16X50_H_
#include "pci.h"
typedef pci_driver_t uart_16x50_driver_t;
void uart_16x50_init(uart_16x50_driver_t *c_this,
pci_config_addr_t pci_addr,
uint16_t dl);
void uart_16x50_tx(uart_16x50_driver_t c_this, uint8_t c);
#endif /* CPU_X86_DRIVERS_LEGACY_PC_UART_16X50_H_ */