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/*
* SPDX-License-Identifier: BSD-2-Clause
*
* Copyright (c) 2022 StarFive Technology Co., Ltd.
*
* Author: Jun Liang Tan <junliang.tan@linux.starfivetech.com>
*/
#include <sbi/sbi_domain.h>
#include <sbi/riscv_asm.h>
#include <sbi/riscv_io.h>
#include <sbi/sbi_console.h>
#include <sbi_utils/serial/cadence-uart.h>
/* clang-format off */
#define UART_REG_CTRL 0x00
#define UART_REG_MODE 0x04
#define UART_REG_IDR 0x0C
#define UART_REG_BRGR 0x18
#define UART_REG_CSR 0x2C
#define UART_REG_RFIFO_TFIFO 0x30
#define UART_REG_BDIVR 0x34
#define UART_CTRL_RXRES 0x00000001
#define UART_CTRL_TXRES 0x00000002
#define UART_CTRL_RXEN 0x00000004
#define UART_CTRL_RXDIS 0x00000008
#define UART_CTRL_TXEN 0x00000010
#define UART_CTRL_TXDIS 0x00000020
#define UART_MODE_PAR_NONE 0x00000020 /* No parity set */
#define UART_BRGR_CD_CLKDIVISOR 0x00000001 /* baud_sample = sel_clk */
#define UART_CSR_REMPTY 0x00000002
#define UART_CSR_TFUL 0x00000010
/* clang-format on */
static volatile void *uart_base;
static u32 uart_in_freq;
static u32 uart_baudrate;
/*
* Find minimum divisor divides in_freq to max_target_hz;
* Based on SiFive UART driver (sifive-uart.c)
*/
static inline unsigned int uart_min_clk_divisor(uint64_t in_freq,
uint64_t max_target_hz)
{
uint64_t quotient = (in_freq + max_target_hz - 1) / (max_target_hz);
/* Avoid underflow */
if (quotient == 0)
return 0;
else
return quotient - 1;
}
static u32 get_reg(u32 offset)
{
return readl(uart_base + offset);
}
static void set_reg(u32 offset, u32 val)
{
writel(val, uart_base + offset);
}
static void cadence_uart_putc(char ch)
{
while (get_reg(UART_REG_CSR) & UART_CSR_TFUL)
;
set_reg(UART_REG_RFIFO_TFIFO, ch);
}
static int cadence_uart_getc(void)
{
u32 ret = get_reg(UART_REG_CSR);
if (!(ret & UART_CSR_REMPTY))
return get_reg(UART_REG_RFIFO_TFIFO);
return -1;
}
static struct sbi_console_device cadence_console = {
.name = "cadence_uart",
.console_putc = cadence_uart_putc,
.console_getc = cadence_uart_getc
};
int cadence_uart_init(unsigned long base, u32 in_freq, u32 baudrate)
{
uart_base = (volatile void *)base;
uart_in_freq = in_freq;
uart_baudrate = baudrate;
/* Disable interrupts */
set_reg(UART_REG_IDR, 0xFFFFFFFF);
/* Disable TX RX */
set_reg(UART_REG_CTRL, UART_CTRL_TXDIS | UART_CTRL_RXDIS);
/* Configure baudrate */
if (in_freq && baudrate) {
set_reg(UART_REG_BRGR, UART_BRGR_CD_CLKDIVISOR);
set_reg(UART_REG_BDIVR,
uart_min_clk_divisor(in_freq, baudrate));
}
/* Software reset TX RX data path and enable TX RX */
set_reg(UART_REG_CTRL, UART_CTRL_TXRES | UART_CTRL_RXRES
| UART_CTRL_TXEN | UART_CTRL_RXEN);
/*
* Set:
* 1 stop bit, bits[07:06] = 0x00,
* no parity set, bits[05:03] = 0x100,
* 8 bits character length, bits[02:01] = 0x00,
* sel_clk = uart_clk, bit[0] = 0x0
*/
set_reg(UART_REG_MODE, UART_MODE_PAR_NONE);
sbi_console_set_device(&cadence_console);
return sbi_domain_root_add_memrange(base, PAGE_SIZE, PAGE_SIZE,
(SBI_DOMAIN_MEMREGION_MMIO |
SBI_DOMAIN_MEMREGION_SHARED_SURW_MRW));
}
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