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Diffstat (limited to 'src/soc/mediatek/mt8173/uart.c')
| -rw-r--r-- | src/soc/mediatek/mt8173/uart.c | 189 |
1 files changed, 189 insertions, 0 deletions
diff --git a/src/soc/mediatek/mt8173/uart.c b/src/soc/mediatek/mt8173/uart.c new file mode 100644 index 0000000000..bd239c7990 --- /dev/null +++ b/src/soc/mediatek/mt8173/uart.c @@ -0,0 +1,189 @@ +/* + * This file is part of the coreboot project. + * + * Copyright 2015 MediaTek Inc. + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation; version 2 of the License. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program; if not, write to the Free Software + * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA + */ + +#include <arch/io.h> +#include <boot/coreboot_tables.h> +#include <console/console.h> /* for __console definition */ +#include <console/uart.h> +#include <drivers/uart/uart8250reg.h> +#include <stdint.h> + +#include <soc/addressmap.h> + +struct mtk_uart { + union { + uint32_t thr; /* Transmit holding register. */ + uint32_t rbr; /* Receive buffer register. */ + uint32_t dll; /* Divisor latch lsb. */ + }; + union { + uint32_t ier; /* Interrupt enable register. */ + uint32_t dlm; /* Divisor latch msb. */ + }; + union { + uint32_t iir; /* Interrupt identification register. */ + uint32_t fcr; /* FIFO control register. */ + uint32_t efr; /* Enhanced feature register. */ + }; + uint32_t lcr; /* Line control register. */ + union { + uint32_t mcr; /* Modem control register. */ + uint32_t xn1; /* XON1 */ + }; + union { + uint32_t lsr; /* Line status register. */ + uint32_t xn2; /* XON2 */ + }; + union { + uint32_t msr; /* Modem status register. */ + uint32_t xf1; /* XOFF1 */ + }; + union { + uint32_t scr; /* Scratch register. */ + uint32_t xf2; /* XOFF2 */ + }; + uint32_t autobaud_en; /* Enable auto baudrate. */ + uint32_t highspeed; /* High speed UART. */ +} __attribute__ ((packed)); + +/* Peripheral Reset and Power Down registers */ +struct mtk_peri_globalcon { + uint32_t rst0; + uint32_t rst1; + uint32_t pdn0_set; + uint32_t pdn1_set; + uint32_t pdn0_clr; + uint32_t pdn1_clr; + uint32_t pdn0_sta; + uint32_t pdn1_sta; + uint32_t pdn_md1_set; + uint32_t pdn_md2_set; + uint32_t pdn_md1_clr; + uint32_t pdn_md2_clr; + uint32_t pdn_md1_sta; + uint32_t pdn_md2_sta; + uint32_t pdn_md_mask; +} __attribute__ ((packed)); + +static struct mtk_uart *const uart_ptr = (void *)UART0_BASE; + +static void mtk_uart_tx_flush(void); +static int mtk_uart_tst_byte(void); + +static void mtk_uart_init(void) +{ + /* Use a hardcoded divisor for now. */ + const unsigned uartclk = 26 * MHz; + const unsigned baudrate = CONFIG_TTYS0_BAUD; + const uint8_t line_config = UART8250_LCR_WLS_8; /* 8n1 */ + unsigned highspeed, quot, divisor, remainder; + + if (baudrate <= 115200) { + highspeed = 0; + quot = 16; + } else { + highspeed = 2; + quot = 4; + } + + /* Set divisor DLL and DLH */ + divisor = uartclk / (quot * baudrate); + remainder = uartclk % (quot * baudrate); + + if (remainder >= (quot / 2) * baudrate) + divisor += 1; + + mtk_uart_tx_flush(); + + /* Disable interrupts. */ + write8(&uart_ptr->ier, 0); + /* Force DTR and RTS to high. */ + write8(&uart_ptr->mcr, UART8250_MCR_DTR | UART8250_MCR_RTS); + /* Set High speed UART register. */ + write8(&uart_ptr->highspeed, highspeed); + /* Set line configuration, access divisor latches. */ + write8(&uart_ptr->lcr, UART8250_LCR_DLAB | line_config); + /* Set the divisor. */ + write8(&uart_ptr->dll, divisor & 0xff); + write8(&uart_ptr->dlm, (divisor >> 8) & 0xff); + /* Hide the divisor latches. */ + write8(&uart_ptr->lcr, line_config); + /* Enable FIFOs, and clear receive and transmit. */ + write8(&uart_ptr->fcr, + UART8250_FCR_FIFO_EN | UART8250_FCR_CLEAR_RCVR | + UART8250_FCR_CLEAR_XMIT); + +} + +static void mtk_uart_tx_byte(unsigned char data) +{ + while (!(read8(&uart_ptr->lsr) & UART8250_LSR_THRE)); + write8(&uart_ptr->thr, data); +} + +static void mtk_uart_tx_flush(void) +{ + while (!(read8(&uart_ptr->lsr) & UART8250_LSR_TEMT)); +} + +static unsigned char mtk_uart_rx_byte(void) +{ + if (!mtk_uart_tst_byte()) + return 0; + return read8(&uart_ptr->rbr); +} + +static int mtk_uart_tst_byte(void) +{ + return (read8(&uart_ptr->lsr) & UART8250_LSR_DR) == UART8250_LSR_DR; +} + +void uart_init(int idx) +{ + mtk_uart_init(); +} + +unsigned char uart_rx_byte(int idx) +{ + return mtk_uart_rx_byte(); +} + +void uart_tx_byte(int idx, unsigned char data) +{ + mtk_uart_tx_byte(data); +} + +void uart_tx_flush(int idx) +{ + mtk_uart_tx_flush(); +} + +#ifndef __PRE_RAM__ +void uart_fill_lb(void *data) +{ + struct lb_serial serial; + serial.type = LB_SERIAL_TYPE_MEMORY_MAPPED; + serial.baseaddr = UART0_BASE; + serial.baud = default_baudrate(); + serial.regwidth = 1; + lb_add_serial(&serial, data); + + lb_add_console(LB_TAG_CONSOLE_SERIAL8250MEM, data); +} +#endif |