u-boot/arch/x86/cpu/braswell/early_uart.c

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// SPDX-License-Identifier: GPL-2.0+
/*
* Copyright (C) 2017, Bin Meng <bmeng.cn@gmail.com>
*/
#include <common.h>
#include <asm/io.h>
#define PCI_DEV_CONFIG(segbus, dev, fn) ( \
(((segbus) & 0xfff) << 20) | \
(((dev) & 0x1f) << 15) | \
(((fn) & 0x07) << 12))
/* Platform Controller Unit */
#define LPC_DEV 0x1f
#define LPC_FUNC 0
/* Enable UART */
#define UART_CONT 0x80
/* UART PAD definitions */
#define UART_RXD_COMMUITY 1
#define UART_TXD_COMMUITY 1
#define UART_RXD_FAMILY 4
#define UART_TXD_FAMILY 4
#define UART_RXD_PAD 2
#define UART_TXD_PAD 7
#define UART_RXD_FUNC 3
#define UART_TXD_FUNC 3
/* IO Memory */
#define IO_BASE_ADDRESS 0xfed80000
static inline uint32_t gpio_pconf0(int community, int family, int pad)
{
return IO_BASE_ADDRESS + community * 0x8000 + 0x4400 +
family * 0x400 + pad * 8;
}
static void gpio_select_func(int community, int family, int pad, int func)
{
uint32_t pconf0_addr = gpio_pconf0(community, family, pad);
clrsetbits_le32(pconf0_addr, 0xf << 16, func << 16);
}
static void x86_pci_write_config32(int dev, unsigned int where, u32 value)
{
unsigned long addr;
addr = CONFIG_PCIE_ECAM_BASE | dev | (where & ~3);
writel(value, addr);
}
/* This can be called after memory-mapped PCI is working */
int setup_internal_uart(int enable)
{
/* Enable or disable the legacy UART hardware */
x86_pci_write_config32(PCI_DEV_CONFIG(0, LPC_DEV, LPC_FUNC), UART_CONT,
enable);
/* All done for the disable part, so just return */
if (!enable)
return 0;
/*
* Set up the pads to the UART function. This allows the signals to
* leave the chip
*/
gpio_select_func(UART_RXD_COMMUITY, UART_RXD_FAMILY,
UART_RXD_PAD, UART_RXD_FUNC);
gpio_select_func(UART_TXD_COMMUITY, UART_TXD_FAMILY,
UART_TXD_PAD, UART_TXD_FUNC);
return 0;
}
void board_debug_uart_init(void)
{
setup_internal_uart(1);
}