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

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// SPDX-License-Identifier: GPL-2.0+
/*
* Copyright (C) 2015 Google, Inc
*/
#include <common.h>
#include <errno.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
/* SCORE Pad definitions */
#define UART_RXD_PAD 82
#define UART_TXD_PAD 83
/* Pad base: PAD_CONF0[n]= PAD_BASE + 16 * n */
#define GPSCORE_PAD_BASE (IO_BASE_ADDRESS + IO_BASE_OFFSET_GPSCORE)
/* IO Memory */
#define IO_BASE_ADDRESS 0xfed0c000
#define IO_BASE_OFFSET_GPSCORE 0x0000
#define IO_BASE_OFFSET_GPNCORE 0x1000
#define IO_BASE_OFFSET_GPSSUS 0x2000
#define IO_BASE_SIZE 0x4000
static inline unsigned int score_pconf0(int pad_num)
{
return GPSCORE_PAD_BASE + pad_num * 16;
}
static void score_select_func(int pad, int func)
{
uint32_t reg;
uint32_t pconf0_addr = score_pconf0(pad);
reg = readl(pconf0_addr);
reg &= ~0x7;
reg |= func & 0x7;
writel(reg, pconf0_addr);
}
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
*/
score_select_func(UART_RXD_PAD, 1);
score_select_func(UART_TXD_PAD, 1);
/* TODO(sjg@chromium.org): Call debug_uart_init() */
return 0;
}
void board_debug_uart_init(void)
{
setup_internal_uart(1);
}