early_serial.c

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/* SPDX-License-Identifier: GPL-2.0-or-later */
 
/* Pre-RAM driver for SMSC LPC47N217 Super I/O chip. */
 
#include <arch/io.h>
#include <device/pnp_ops.h>
#include <assert.h>
#include "lpc47n217.h"
 
static void pnp_enter_conf_state(pnp_devfn_t dev)
{
        u16 port = dev >> 8;
        outb(0x55, port);
}
 
static void pnp_exit_conf_state(pnp_devfn_t dev)
{
        u16 port = dev >> 8;
        outb(0xaa, port);
}
 
/**
 * Program the base I/O port for the specified logical device.
 *
 * @param dev High 8 bits = Super I/O port, low 8 bits = logical device number.
 * @param iobase Base I/O port for the logical device.
 */
static void lpc47n217_pnp_set_iobase(pnp_devfn_t dev, u16 iobase)
{
        /* LPC47N217 requires base ports to be a multiple of 4. */
        ASSERT(!(iobase & 0x3));
 
        switch (dev & 0xFF) {
        case LPC47N217_PP:
                pnp_write_config(dev, 0x23, (iobase >> 2) & 0xff);
                break;
        case LPC47N217_SP1:
                pnp_write_config(dev, 0x24, (iobase >> 2) & 0xff);
                break;
        case LPC47N217_SP2:
                pnp_write_config(dev, 0x25, (iobase >> 2) & 0xff);
                break;
        default:
                break;
        }
}
 
/**
 * Enable or disable the specified logical device.
 *
 * Technically, a full disable requires setting the device's base I/O port
 * below 0x100. We don't do that here, because we don't have access to a data
 * structure that specifies what the 'real' base port is (when asked to enable
 * the device). Also the function is used only to disable the device while its
 * true base port is programmed (see lpc47n217_enable_serial() below).
 *
 * @param dev High 8 bits = Super I/O port, low 8 bits = logical device number.
 * @param enable 0 to disable, anything else to enable.
 */
static void lpc47n217_pnp_set_enable(pnp_devfn_t dev, int enable)
{
        u8 power_register = 0, power_mask = 0, current_power, new_power;
 
        switch (dev & 0xFF) {
        case LPC47N217_PP:
                power_register = 0x01;
                power_mask = 0x04;
                break;
        case LPC47N217_SP1:
                power_register = 0x02;
                power_mask = 0x08;
                break;
        case LPC47N217_SP2:
                power_register = 0x02;
                power_mask = 0x80;
                break;
        default:
                return;
        }
 
        current_power = pnp_read_config(dev, power_register);
        new_power = current_power & ~power_mask; /* Disable by default. */
        if (enable)
                new_power |= power_mask;         /* Enable. */
        pnp_write_config(dev, power_register, new_power);
}
 
/**
 * Configure the base I/O port of the specified serial device and enable the
 * serial device.
 *
 * @param dev High 8 bits = Super I/O port, low 8 bits = logical device number.
 * @param iobase Processor I/O port address to assign to this serial device.
 */
void lpc47n217_enable_serial(pnp_devfn_t dev, u16 iobase)
{
        /*
         * NOTE: Cannot use pnp_set_XXX() here because they assume chip
         * support for logical devices, which the LPC47N217 doesn't have.
         */
        pnp_enter_conf_state(dev);
        lpc47n217_pnp_set_enable(dev, 0);
        lpc47n217_pnp_set_iobase(dev, iobase);
        lpc47n217_pnp_set_enable(dev, 1);
        pnp_exit_conf_state(dev);
}