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Diffstat (limited to 'src/soc/imgtec/pistachio/uart.c')
| -rw-r--r-- | src/soc/imgtec/pistachio/uart.c | 217 |
1 files changed, 217 insertions, 0 deletions
diff --git a/src/soc/imgtec/pistachio/uart.c b/src/soc/imgtec/pistachio/uart.c new file mode 100644 index 0000000000..53bf21d226 --- /dev/null +++ b/src/soc/imgtec/pistachio/uart.c @@ -0,0 +1,217 @@ +/* + * This file is part of the coreboot project. + * + * Copyright (C) 2003 Eric Biederman + * Copyright (C) 2006-2010 coresystems GmbH + * Copyright (C) 2014 Imagination Technologies + * + * 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 <console/console.h> +#include <device/device.h> +#include <delay.h> +#include <uart.h> +#include <uart8250.h> + +/* Should support 8250, 16450, 16550, 16550A type UARTs */ + +/* Expected character delay at 1200bps is 9ms for a working UART + * and no flow-control. Assume UART as stuck if shift register + * or FIFO takes more than 50ms per character to appear empty. + */ +#define SINGLE_CHAR_TIMEOUT (50 * 1000) +#define FIFO_TIMEOUT (16 * SINGLE_CHAR_TIMEOUT) +#define UART_SHIFT 2 + +#define GEN_ACCESSOR(name, idx) \ +static inline uint8_t read_##name(unsigned base_port) \ +{ \ + return read8(base_port + (idx << UART_SHIFT)); \ +} \ + \ +static inline void write_##name(unsigned base_port, uint8_t val) \ +{ \ + write8(base_port + (idx << UART_SHIFT), val); \ +} + +GEN_ACCESSOR(rbr, UART8250_RBR) +GEN_ACCESSOR(tbr, UART8250_TBR) +GEN_ACCESSOR(ier, UART8250_IER) +GEN_ACCESSOR(fcr, UART8250_FCR) +GEN_ACCESSOR(lcr, UART8250_LCR) +GEN_ACCESSOR(mcr, UART8250_MCR) +GEN_ACCESSOR(lsr, UART8250_LSR) +GEN_ACCESSOR(dll, UART8250_DLL) +GEN_ACCESSOR(dlm, UART8250_DLM) + +static int uart8250_mem_can_tx_byte(unsigned base_port) +{ + return read_lsr(base_port) & UART8250_LSR_THRE; +} + +static void uart8250_mem_tx_byte(unsigned base_port, unsigned char data) +{ + unsigned long int i = SINGLE_CHAR_TIMEOUT; + while (i-- && !uart8250_mem_can_tx_byte(base_port)) + udelay(1); + write_tbr(base_port, data); +} + +static void uart8250_mem_tx_flush(unsigned base_port) +{ + unsigned long int i = FIFO_TIMEOUT; + while (i-- && !(read_lsr(base_port) & UART8250_LSR_TEMT)) + udelay(1); +} + +static int uart8250_mem_can_rx_byte(unsigned base_port) +{ + return read_lsr(base_port) & UART8250_LSR_DR; +} + +static unsigned char uart8250_mem_rx_byte(unsigned base_port) +{ + unsigned long int i = SINGLE_CHAR_TIMEOUT; + while (i-- && !uart8250_mem_can_rx_byte(base_port)) + udelay(1); + if (i) + return read_rbr(base_port); + else + return 0x0; +} + +static void uart8250_mem_init(unsigned base_port, unsigned divisor) +{ + /* Disable interrupts */ + write_ier(base_port, 0x0); + /* Enable FIFOs */ + write_fcr(base_port, UART8250_FCR_FIFO_EN); + + /* Assert DTR and RTS so the other end is happy */ + write_mcr(base_port, UART8250_MCR_DTR | UART8250_MCR_RTS); + + /* DLAB on */ + write_lcr(base_port, UART8250_LCR_DLAB | CONFIG_TTYS0_LCS); + + write_dll(base_port, divisor & 0xFF); + write_dlm(base_port, (divisor >> 8) & 0xFF); + + /* Set to 3 for 8N1 */ + write_lcr(base_port, CONFIG_TTYS0_LCS); +} + +static unsigned int uart_platform_refclk(void) +{ + /* TODO: this is entirely arbitrary */ + return 1000000; +} + +static unsigned int uart_platform_base(int idx) +{ + switch (idx) { + case 0: + return 0xb8101400; + + case 1: + return 0xb8101500; + + default: + return 0x0; + } +} + +/* Calculate divisor. Do not floor but round to nearest integer. */ +static unsigned int uart_baudrate_divisor(unsigned int baudrate, + unsigned int refclk, unsigned int oversample) +{ + return (1 + (2 * refclk) / (baudrate * oversample)) / 2; +} + +static void pistachio_uart_init(void) +{ + u32 base = uart_platform_base(0); + if (!base) + return; + + unsigned int div; + div = uart_baudrate_divisor(CONFIG_TTYS0_BAUD, + uart_platform_refclk(), 16); + uart8250_mem_init(base, div); +} + +static void pistachio_uart_tx_byte(unsigned char data) +{ + u32 base = uart_platform_base(0); + if (!base) + return; + uart8250_mem_tx_byte(base, data); +} + +static unsigned char pistachio_uart_rx_byte(void) +{ + u32 base = uart_platform_base(0); + if (!base) + return 0xff; + return uart8250_mem_rx_byte(base); +} + +static void pistachio_uart_tx_flush(void) +{ + u32 base = uart_platform_base(0); + if (!base) + return; + uart8250_mem_tx_flush(base); +} + +#if !defined(__PRE_RAM__) + +static const struct console_driver pistachio_uart_console __console = { + .init = pistachio_uart_init, + .tx_byte = pistachio_uart_tx_byte, + .tx_flush = pistachio_uart_tx_flush, + .rx_byte = pistachio_uart_rx_byte, +}; + +uint32_t uartmem_getbaseaddr(void) +{ + return uart_platform_base(0); +} + +#else /* __PRE_RAM__ */ + +void uart_init(void) +{ + pistachio_uart_init(); +} + +void uart_tx_byte(unsigned char data) +{ + pistachio_uart_tx_byte(data); +} + +unsigned char uart_rx_byte(void) +{ + return pistachio_uart_rx_byte(); +} + +void uart_tx_flush(void) +{ + pistachio_uart_tx_flush(); +} + +#endif /* __PRE_RAM__ */ |