diff options
Diffstat (limited to 'src/soc/samsung/exynos5420/uart.c')
| -rw-r--r-- | src/soc/samsung/exynos5420/uart.c | 194 |
1 files changed, 194 insertions, 0 deletions
diff --git a/src/soc/samsung/exynos5420/uart.c b/src/soc/samsung/exynos5420/uart.c new file mode 100644 index 0000000000..be96d5b86c --- /dev/null +++ b/src/soc/samsung/exynos5420/uart.c @@ -0,0 +1,194 @@ +/* + * This file is part of the coreboot project. + * + * Copyright (C) 2009 Samsung Electronics + * + * 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 <types.h> +#include <console/uart.h> +#include <arch/io.h> +#include <boot/coreboot_tables.h> +#include "uart.h" +#include "clk.h" +#include "cpu.h" +#include "periph.h" +#include "uart.h" + +#define RX_FIFO_COUNT_MASK 0xff +#define RX_FIFO_FULL_MASK (1 << 8) +#define TX_FIFO_FULL_MASK (1 << 24) + + +/* + * The coefficient, used to calculate the baudrate on S5P UARTs is + * calculated as + * C = UBRDIV * 16 + number_of_set_bits_in_UDIVSLOT + * however, section 31.6.11 of the datasheet doesn't recomment using 1 for 1, + * 3 for 2, ... (2^n - 1) for n, instead, they suggest using these constants: + */ +static const int udivslot[] = { + 0, + 0x0080, + 0x0808, + 0x0888, + 0x2222, + 0x4924, + 0x4a52, + 0x54aa, + 0x5555, + 0xd555, + 0xd5d5, + 0xddd5, + 0xdddd, + 0xdfdd, + 0xdfdf, + 0xffdf, +}; + +static void serial_setbrg_dev(struct s5p_uart *uart) +{ + u32 uclk; + u32 val; + + // All UARTs share the same clock. + uclk = clock_get_periph_rate(PERIPH_ID_UART3); + val = uclk / default_baudrate(); + + writel(val / 16 - 1, &uart->ubrdiv); + + /* + * FIXME(dhendrix): the original uart.h had a "br_rest" value which + * does not seem relevant to the exynos5420... not entirely sure + * where/if we need to worry about it here + */ +#if 0 + if (s5p_uart_divslot()) + writel(udivslot[val % 16], &uart->rest.slot); + else + writeb(val % 16, &uart->rest.value); +#endif +} + +/* + * Initialise the serial port with the given baudrate. The settings + * are always 8 data bits, no parity, 1 stop bit, no start bits. + */ +static void exynos5_init_dev(struct s5p_uart *uart) +{ + /* enable FIFOs */ + writel(0x1, &uart->ufcon); + writel(0, &uart->umcon); + /* 8N1 */ + writel(0x3, &uart->ulcon); + /* No interrupts, no DMA, pure polling */ + writel(0x245, &uart->ucon); + + serial_setbrg_dev(uart); +} + +static int exynos5_uart_err_check(struct s5p_uart *uart, int op) +{ + unsigned int mask; + + /* + * UERSTAT + * Break Detect [3] + * Frame Err [2] : receive operation + * Parity Err [1] : receive operation + * Overrun Err [0] : receive operation + */ + if (op) + mask = 0x8; + else + mask = 0xf; + + return readl(&uart->uerstat) & mask; +} + +/* + * Read a single byte from the serial port. Returns 1 on success, 0 + * otherwise. When the function is succesfull, the character read is + * written into its argument c. + */ +static unsigned char exynos5_uart_rx_byte(struct s5p_uart *uart) +{ + /* wait for character to arrive */ + while (!(readl(&uart->ufstat) & (RX_FIFO_COUNT_MASK | + RX_FIFO_FULL_MASK))) { + if (exynos5_uart_err_check(uart, 0)) + return 0; + } + + return readb(&uart->urxh) & 0xff; +} + +/* + * Output a single byte to the serial port. + */ +static void exynos5_uart_tx_byte(struct s5p_uart *uart, unsigned char data) +{ + /* wait for room in the tx FIFO */ + while ((readl(&uart->ufstat) & TX_FIFO_FULL_MASK)) { + if (exynos5_uart_err_check(uart, 1)) + return; + } + + writeb(data, &uart->utxh); +} + +unsigned int uart_platform_base(int idx) +{ + if (idx < 4) + return 0x12c00000 + idx * 0x10000; + else + return 0; +} + +void uart_init(int idx) +{ + struct s5p_uart *uart = uart_platform_baseptr(idx); + exynos5_init_dev(uart); +} + +unsigned char uart_rx_byte(int idx) +{ + struct s5p_uart *uart = uart_platform_baseptr(idx); + return exynos5_uart_rx_byte(uart); +} + +void uart_tx_byte(int idx, unsigned char data) +{ + struct s5p_uart *uart = uart_platform_baseptr(idx); + exynos5_uart_tx_byte(uart, data); +} + +void uart_tx_flush(int idx) +{ + /* Exynos5250 implements this too. */ +} + +#ifndef __PRE_RAM__ +void uart_fill_lb(void *data) +{ + struct lb_serial serial; + serial.type = LB_SERIAL_TYPE_MEMORY_MAPPED; + serial.baseaddr = uart_platform_base(CONFIG_UART_FOR_CONSOLE); + serial.baud = default_baudrate(); + lb_add_serial(&serial, data); + + lb_add_console(LB_TAG_CONSOLE_SERIAL8250MEM, data); +} +#endif |