f81866d_uart.c

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/* SPDX-License-Identifier: GPL-2.0-or-later */
 
#include <console/console.h>
#include <device/device.h>
#include <device/pnp.h>
#include "fintek_internal.h"
#include "f81866d.h"
 
#define LDN_REG                 0x07
#define PORT_SELECT_REGISTER    0x27
#define MULTI_FUNC_SEL3_REG     0x29
#define IRQ_SHARE_REGISTER      0xF0
#define FIFO_SEL_MODE           0xF6
 
/*
 * f81866d_uart_init enables all necessary registers for UART 3/4
 * Fintek needs to know if pins are used as GPIO or UART pins
 * Share interrupt usage needs to be enabled
 */
void f81866d_uart_init(struct device *dev)
{
        struct resource *res = probe_resource(dev, PNP_IDX_IO0);
        u8 tmp;
 
        if (!res) {
                printk(BIOS_WARNING, "%s: No UART resource found.\n", __func__);
                return;
        }
 
        pnp_enter_conf_mode(dev);
 
        // Set Port Select Register (Bit 0) = 0
        // before accessing Multi Function Select 3 Register
        tmp = pnp_read_config(dev, PORT_SELECT_REGISTER);
        pnp_write_config(dev, PORT_SELECT_REGISTER, tmp & 0xFE);
 
        // Set UART 3 function (Bit 4/5), otherwise pin 36-43 are GPIO
        if (dev->path.pnp.device == F81866D_SP3) {
                tmp = pnp_read_config(dev, MULTI_FUNC_SEL3_REG);
                pnp_write_config(dev, MULTI_FUNC_SEL3_REG, tmp | 0x30);
        }
 
        // Set UART 4 function (Bit 6/7), otherwise pin 44-51 are GPIO
        if (dev->path.pnp.device == F81866D_SP4) {
                tmp = pnp_read_config(dev, MULTI_FUNC_SEL3_REG);
                pnp_write_config(dev, MULTI_FUNC_SEL3_REG, tmp | 0xC0);
        }
 
        // Select UART X in LDN register
        pnp_write_config(dev, LDN_REG, dev->path.pnp.device & 0xff);
        // Set IRQ trigger mode from active low to high (Bit 3)
        tmp = pnp_read_config(dev, FIFO_SEL_MODE);
        pnp_write_config(dev, FIFO_SEL_MODE, tmp | 0x8);
        // Enable share interrupt (Bit 0)
        pnp_write_config(dev, IRQ_SHARE_REGISTER, 0x01);
 
        pnp_exit_conf_mode(dev);
}