hda_verb.c

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/* SPDX-License-Identifier: GPL-2.0-only */
 
#include <console/console.h>
#include <device/azalia_device.h>
#include <device/mmio.h>
 
#include "hda_verb.h"
 
int hda_codec_detect(u8 *base)
{
        u8 reg8;
 
        /* Set Bit 0 to 1 to exit reset state (BAR + 0x8)[0] */
        if (azalia_exit_reset(base) < 0)
                goto no_codec;
 
        /* Write back the value once reset bit is set. */
        write16(base + HDA_GCAP_REG, read16(base + HDA_GCAP_REG));
 
        /*
         * Clear the "State Change Status Register" STATESTS bits
         * for each of the "SDIN Stat Change Status Flag"
         */
        write8(base + HDA_STATESTS_REG, 0xf);
 
        /* Turn off the link and poll RESET# bit until it reads back as 0 */
        if (azalia_enter_reset(base) < 0)
                goto no_codec;
 
        /* Turn on the link and poll RESET# bit until it reads back as 1 */
        if (azalia_exit_reset(base) < 0)
                goto no_codec;
 
        /* Read in Codec location (BAR + 0xe)[2..0] */
        reg8 = read8(base + HDA_STATESTS_REG);
        reg8 &= 0x0f;
        if (!reg8)
                goto no_codec;
 
        return reg8;
 
no_codec:
        /* Codec not found, put HDA back in reset */
        azalia_enter_reset(base);
        printk(BIOS_DEBUG, "HDA: No codec!\n");
        return 0;
}