180 lines
6.5 KiB
C
180 lines
6.5 KiB
C
/*
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* Copyright (C) 2015, Intel Corporation. All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* 3. Neither the name of the copyright holder nor the names of its
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* contributors may be used to endorse or promote products derived
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* from this software without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
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* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
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* COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
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* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
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* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
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* STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
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* OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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#include <stdlib.h>
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#include "helpers.h"
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#include "paging.h"
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#include "prot-domains.h"
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#include "syscalls.h"
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#include "uart-16x50.h"
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/* Refer to Intel Quark SoC X1000 Datasheet, Chapter 18 for more details on
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* UART operation.
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*/
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/* Divisor Latch Access Bit (DLAB) mask for Line Control Register (LCR).
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*
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* When bit is set, enables access to divisor registers to set baud rate. When
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* clear, enables access to other registers mapped to the same addresses as the
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* divisor registers.
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*/
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#define UART_LCR_7_DLAB BIT(7)
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/* Setting for LCR that configures the UART to operate with no parity, 1 stop
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* bit, and eight bits per character.
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*/
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#define UART_LCR_8BITS 0x03
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/* FIFO Control Register (FCR) bitmasks */
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#define UART_FCR_0_FIFOE BIT(0) /*< enable FIFOs */
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#define UART_FCR_1_RFIFOR BIT(1) /*< reset RX FIFO */
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#define UART_FCR_2_XFIFOR BIT(2) /*< reset TX FIFO */
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/* Line Status Register (LSR) Transmit Holding Register Empty bitmask to check
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* whether the Transmit Holding Register (THR) or TX FIFO is empty.
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*/
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#define UART_LSR_5_THRE BIT(5)
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/* MMIO registers for UART */
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typedef struct uart_16x50_regs {
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volatile uint32_t rbr_thr_dll, ier_dlh, iir_fcr, lcr;
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volatile uint32_t mcr, lsr, msr, scr, usr, htx, dmasa;
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} uart_16x50_regs_t;
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#if X86_CONF_PROT_DOMAINS == X86_CONF_PROT_DOMAINS__PAGING
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/* When paging-based protection domains are in use, at least one page of memory
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* must be reserved to facilitate access to the MMIO region, since that is the
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* smallest unit of memory that can be managed with paging:
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*/
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#define UART_MMIO_SZ MIN_PAGE_SIZE
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#else
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/* Multi-segment protection domain implementations can control memory with
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* byte granularity. Thus, only the registers defined in the uart_16x50_regs
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* structure are included in the MMIO region allocated for this protection
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* domain:
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*/
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#define UART_MMIO_SZ sizeof(uart_16x50_regs_t)
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#endif
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void uart_16x50_setup(uart_16x50_driver_t c_this, uint16_t dl);
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/*---------------------------------------------------------------------------*/
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SYSCALLS_DEFINE(uart_16x50_setup, uart_16x50_driver_t c_this, uint16_t dl)
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{
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uart_16x50_regs_t ATTR_MMIO_ADDR_SPACE *regs =
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(uart_16x50_regs_t ATTR_MMIO_ADDR_SPACE *)PROT_DOMAINS_MMIO(c_this);
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prot_domains_enable_mmio();
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/* Set the DLAB bit to enable access to divisor settings. */
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MMIO_WRITEL(regs->lcr, UART_LCR_7_DLAB);
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/* The divisor settings configure the baud rate, and may need to be defined
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* on a per-device basis.
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*/
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MMIO_WRITEL(regs->rbr_thr_dll, dl & UINT8_MAX);
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MMIO_WRITEL(regs->ier_dlh, dl >> 8);
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/* Clear the DLAB bit to enable access to other settings and configure other
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* UART parameters.
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*/
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MMIO_WRITEL(regs->lcr, UART_LCR_8BITS);
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/* Enable the FIFOs. */
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MMIO_WRITEL(regs->iir_fcr,
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UART_FCR_0_FIFOE | UART_FCR_1_RFIFOR | UART_FCR_2_XFIFOR);
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prot_domains_disable_mmio();
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}
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/*---------------------------------------------------------------------------*/
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/**
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* \brief Transmit a character through a UART.
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* \param c_this Initialized structure representing the device.
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* \param c Character to be transmitted.
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*
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* This procedure will block indefinitely until the UART is ready
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* to accept the character to be transmitted.
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*/
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SYSCALLS_DEFINE(uart_16x50_tx, uart_16x50_driver_t c_this, uint8_t c)
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{
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uint32_t ready;
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uart_16x50_regs_t ATTR_MMIO_ADDR_SPACE *regs =
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(uart_16x50_regs_t ATTR_MMIO_ADDR_SPACE *)PROT_DOMAINS_MMIO(c_this);
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prot_domains_enable_mmio();
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/* Wait for space in TX FIFO. */
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do {
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MMIO_READL(ready, regs->lsr);
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} while((ready & UART_LSR_5_THRE) == 0);
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/* Add character to TX FIFO. */
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MMIO_WRITEL(regs->rbr_thr_dll, c);
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prot_domains_disable_mmio();
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}
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/*---------------------------------------------------------------------------*/
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/**
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* \brief Perform common initialization that must precede per-port
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* initialization.
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*/
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/*---------------------------------------------------------------------------*/
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void
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uart_16x50_init(void)
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{
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SYSCALLS_INIT(uart_16x50_setup);
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SYSCALLS_INIT(uart_16x50_tx);
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}
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/*---------------------------------------------------------------------------*/
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/**
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* \brief Initialize an MMIO-programmable 16X50 UART.
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* \param c_this Structure that will be initialized to represent the device.
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* \param pci_addr PCI address of device.
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* \param dl Divisor setting to configure the baud rate.
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*/
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void
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uart_16x50_init_port(uart_16x50_driver_t ATTR_KERN_ADDR_SPACE *c_this,
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pci_config_addr_t pci_addr,
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uint16_t dl)
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{
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uart_16x50_driver_t loc_c_this;
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/* This assumes that the UART had an MMIO range assigned to it by the
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* firmware during boot.
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*/
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pci_init(c_this, pci_addr, UART_MMIO_SZ, 0, 0);
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SYSCALLS_AUTHZ(uart_16x50_setup, *c_this);
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SYSCALLS_AUTHZ(uart_16x50_tx, *c_this);
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prot_domains_copy_dcd(&loc_c_this, c_this);
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uart_16x50_setup(loc_c_this, dl);
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}
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/*---------------------------------------------------------------------------*/
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