/* SPDX-License-Identifier: GPL-2.0-or-later */ #include <types.h> #include <console/uart.h> #include <device/mmio.h> #include <boot/coreboot_tables.h> #include <cpu/ti/am335x/uart.h> #define EFR_ENHANCED_EN (1 << 4) #define FCR_FIFO_EN (1 << 0) #define MCR_TCR_TLR (1 << 6) #define SYSC_SOFTRESET (1 << 1) #define SYSS_RESETDONE (1 << 0) #define LSR_RXFIFOE (1 << 0) #define LSR_TXFIFOE (1 << 5) /* * Initialise the serial port with the given baudrate divisor. The settings * are always 8 data bits, no parity, 1 stop bit, no start bits. */ static void am335x_uart_init(struct am335x_uart *uart, uint16_t div) { uint16_t lcr_orig, efr_orig, mcr_orig; /* reset the UART */ write16(&uart->sysc, uart->sysc | SYSC_SOFTRESET); while (!(read16(&uart->syss) & SYSS_RESETDONE)) ; /* 1. switch to register config mode B */ lcr_orig = read16(&uart->lcr); write16(&uart->lcr, 0xbf); /* * 2. Set EFR ENHANCED_EN bit. To access this bit, registers must * be in TCR_TLR submode, meaning EFR[4] = 1 and MCR[6] = 1. */ efr_orig = read16(&uart->efr); write16(&uart->efr, efr_orig | EFR_ENHANCED_EN); /* 3. Switch to register config mode A */ write16(&uart->lcr, 0x80); /* 4. Enable register submode TCR_TLR to access the UARTi.UART_TLR */ mcr_orig = read16(&uart->mcr); write16(&uart->mcr, mcr_orig | MCR_TCR_TLR); /* 5. Enable the FIFO. For now we'll ignore FIFO triggers and DMA */ write16(&uart->fcr, FCR_FIFO_EN); /* 6. Switch to configuration mode B */ write16(&uart->lcr, 0xbf); /* Skip steps 7 and 8 (setting up FIFO triggers for DMA) */ /* 9. Restore original EFR value */ write16(&uart->efr, efr_orig); /* 10. Switch to config mode A */ write16(&uart->lcr, 0x80); /* 11. Restore original MCR value */ write16(&uart->mcr, mcr_orig); /* 12. Restore original LCR value */ write16(&uart->lcr, lcr_orig); /* Protocol, baud rate and interrupt settings */ /* 1. Disable UART access to DLL and DLH registers */ write16(&uart->mdr1, read16(&uart->mdr1) | 0x7); /* 2. Switch to config mode B */ write16(&uart->lcr, 0xbf); /* 3. Enable access to IER[7:4] */ write16(&uart->efr, efr_orig | EFR_ENHANCED_EN); /* 4. Switch to operational mode */ write16(&uart->lcr, 0x0); /* 5. Clear IER */ write16(&uart->ier, 0x0); /* 6. Switch to config mode B */ write16(&uart->lcr, 0xbf); /* 7. Set dll and dlh to the desired values (table 19-25) */ write16(&uart->dlh, (div >> 8)); write16(&uart->dll, (div & 0xff)); /* 8. Switch to operational mode to access ier */ write16(&uart->lcr, 0x0); /* 9. Clear ier to disable all interrupts */ write16(&uart->ier, 0x0); /* 10. Switch to config mode B */ write16(&uart->lcr, 0xbf); /* 11. Restore efr */ write16(&uart->efr, efr_orig); /* 12. Set protocol formatting 8n1 (8 bit data, no parity, 1 stop bit) */ write16(&uart->lcr, 0x3); /* 13. Load the new UART mode */ write16(&uart->mdr1, 0x0); } /* * Read a single byte from the serial port. Returns 1 on success, 0 * otherwise. When the function is successful, the character read is * written into its argument c. */ static unsigned char am335x_uart_rx_byte(struct am335x_uart *uart) { while (!(read16(&uart->lsr) & LSR_RXFIFOE)); return read8(&uart->rhr); } /* * Output a single byte to the serial port. */ static void am335x_uart_tx_byte(struct am335x_uart *uart, unsigned char data) { while (!(read16(&uart->lsr) & LSR_TXFIFOE)); return write8(&uart->thr, data); } unsigned int uart_platform_refclk(void) { return 48000000; } uintptr_t uart_platform_base(int idx) { const unsigned int bases[] = { 0x44e09000, 0x48022000, 0x48024000, 0x481a6000, 0x481a8000, 0x481aa000 }; if (idx < ARRAY_SIZE(bases)) return bases[idx]; return 0; } void uart_init(int idx) { struct am335x_uart *uart = uart_platform_baseptr(idx); uint16_t div = (uint16_t) uart_baudrate_divisor( get_uart_baudrate(), uart_platform_refclk(), 16); am335x_uart_init(uart, div); } unsigned char uart_rx_byte(int idx) { struct am335x_uart *uart = uart_platform_baseptr(idx); return am335x_uart_rx_byte(uart); } void uart_tx_byte(int idx, unsigned char data) { struct am335x_uart *uart = uart_platform_baseptr(idx); am335x_uart_tx_byte(uart, data); } void uart_tx_flush(int idx) { } 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 = get_uart_baudrate(); serial.regwidth = 2; serial.input_hertz = uart_platform_refclk(); serial.uart_pci_addr = CONFIG_UART_PCI_ADDR; lb_add_serial(&serial, data); lb_add_console(LB_TAG_CONSOLE_SERIAL8250MEM, data); }