Archipelago » qemu

/*

 * Luminary Micro Stellaris peripherals

 *

 * Copyright (c) 2006 CodeSourcery.

 * Written by Paul Brook

 *

 * This code is licenced under the GPL.

 */

#include "hw.h"

#include "arm-misc.h"

#include "primecell.h"

#include "devices.h"

#include "qemu-timer.h"

#include "i2c.h"

#include "net.h"

#include "sd.h"

#include "sysemu.h"

#include "boards.h"

#define GPIO_A 0

#define GPIO_B 1

#define GPIO_C 2

#define GPIO_D 3

#define GPIO_E 4

#define GPIO_F 5

#define GPIO_G 6

#define BP_OLED_I2C  0x01

#define BP_OLED_SSI  0x02

#define BP_GAMEPAD   0x04

typedef const struct {

    const char *name;

    uint32_t did0;

    uint32_t did1;

    uint32_t dc0;

    uint32_t dc1;

    uint32_t dc2;

    uint32_t dc3;

    uint32_t dc4;

    uint32_t peripherals;

} stellaris_board_info;

/* General purpose timer module.  */

typedef struct gptm_state {

    uint32_t config;

    uint32_t mode[2];

    uint32_t control;

    uint32_t state;

    uint32_t mask;

    uint32_t load[2];

    uint32_t match[2];

    uint32_t prescale[2];

    uint32_t match_prescale[2];

    uint32_t rtc;

    int64_t tick[2];

    struct gptm_state *opaque[2];

    uint32_t base;

    QEMUTimer *timer[2];

    /* The timers have an alternate output used to trigger the ADC.  */

    qemu_irq trigger;

    qemu_irq irq;

} gptm_state;

static void gptm_update_irq(gptm_state *s)

{

    int level;

    level = (s->state & s->mask) != 0;

    qemu_set_irq(s->irq, level);

}

static void gptm_stop(gptm_state *s, int n)

{

    qemu_del_timer(s->timer[n]);

}

static void gptm_reload(gptm_state *s, int n, int reset)

{

    int64_t tick;

    if (reset)

        tick = qemu_get_clock(vm_clock);

    else

        tick = s->tick[n];

    if (s->config == 0) {

        /* 32-bit CountDown.  */

        uint32_t count;

        count = s->load[0] | (s->load[1] << 16);

        tick += (int64_t)count * system_clock_scale;

    } else if (s->config == 1) {

        /* 32-bit RTC.  1Hz tick.  */

        tick += ticks_per_sec;

    } else if (s->mode[n] == 0xa) {

        /* PWM mode.  Not implemented.  */

    } else {

        cpu_abort(cpu_single_env, "TODO: 16-bit timer mode 0x%x\n",

                  s->mode[n]);

    }

    s->tick[n] = tick;

    qemu_mod_timer(s->timer[n], tick);

}

static void gptm_tick(void *opaque)

{

    gptm_state **p = (gptm_state **)opaque;

    gptm_state *s;

    int n;

    s = *p;

    n = p - s->opaque;

    if (s->config == 0) {

        s->state |= 1;

        if ((s->control & 0x20)) {

            /* Output trigger.  */

            qemu_irq_raise(s->trigger);

            qemu_irq_lower(s->trigger);

        }

        if (s->mode[0] & 1) {

            /* One-shot.  */

            s->control &= ~1;

        } else {

            /* Periodic.  */

            gptm_reload(s, 0, 0);

        }

    } else if (s->config == 1) {

        /* RTC.  */

        uint32_t match;

        s->rtc++;

        match = s->match[0] | (s->match[1] << 16);

        if (s->rtc > match)

            s->rtc = 0;

        if (s->rtc == 0) {

            s->state |= 8;

        }

        gptm_reload(s, 0, 0);

    } else if (s->mode[n] == 0xa) {

        /* PWM mode.  Not implemented.  */

    } else {

        cpu_abort(cpu_single_env, "TODO: 16-bit timer mode 0x%x\n",

                  s->mode[n]);

    }

    gptm_update_irq(s);

}

static uint32_t gptm_read(void *opaque, target_phys_addr_t offset)

{

    gptm_state *s = (gptm_state *)opaque;

    offset -= s->base;

    switch (offset) {

    case 0x00: /* CFG */

        return s->config;

    case 0x04: /* TAMR */

        return s->mode[0];

    case 0x08: /* TBMR */

        return s->mode[1];

    case 0x0c: /* CTL */

        return s->control;

    case 0x18: /* IMR */

        return s->mask;

    case 0x1c: /* RIS */

        return s->state;

    case 0x20: /* MIS */

        return s->state & s->mask;

    case 0x24: /* CR */

        return 0;

    case 0x28: /* TAILR */

        return s->load[0] | ((s->config < 4) ? (s->load[1] << 16) : 0);

    case 0x2c: /* TBILR */

        return s->load[1];

    case 0x30: /* TAMARCHR */

        return s->match[0] | ((s->config < 4) ? (s->match[1] << 16) : 0);

    case 0x34: /* TBMATCHR */

        return s->match[1];

    case 0x38: /* TAPR */

        return s->prescale[0];

    case 0x3c: /* TBPR */

        return s->prescale[1];

    case 0x40: /* TAPMR */

        return s->match_prescale[0];

    case 0x44: /* TBPMR */

        return s->match_prescale[1];

    case 0x48: /* TAR */

        if (s->control == 1)

            return s->rtc;

    case 0x4c: /* TBR */

        cpu_abort(cpu_single_env, "TODO: Timer value read\n");

    default:

        cpu_abort(cpu_single_env, "gptm_read: Bad offset 0x%x\n", (int)offset);

        return 0;

    }

}

static void gptm_write(void *opaque, target_phys_addr_t offset, uint32_t value)

{

    gptm_state *s = (gptm_state *)opaque;

    uint32_t oldval;

    offset -= s->base;

    /* The timers should be disabled before changing the configuration.

       We take advantage of this and defer everything until the timer

       is enabled.  */

    switch (offset) {

    case 0x00: /* CFG */

        s->config = value;

        break;

    case 0x04: /* TAMR */

        s->mode[0] = value;

        break;

    case 0x08: /* TBMR */

        s->mode[1] = value;

        break;

    case 0x0c: /* CTL */

        oldval = s->control;

        s->control = value;

        /* TODO: Implement pause.  */

        if ((oldval ^ value) & 1) {

            if (value & 1) {

                gptm_reload(s, 0, 1);

            } else {

                gptm_stop(s, 0);

            }

        }

        if (((oldval ^ value) & 0x100) && s->config >= 4) {

            if (value & 0x100) {

                gptm_reload(s, 1, 1);

            } else {

                gptm_stop(s, 1);

            }

        }

        break;

    case 0x18: /* IMR */

        s->mask = value & 0x77;

        gptm_update_irq(s);

        break;

    case 0x24: /* CR */

        s->state &= ~value;

        break;

    case 0x28: /* TAILR */

        s->load[0] = value & 0xffff;

        if (s->config < 4) {

            s->load[1] = value >> 16;

        }

        break;

    case 0x2c: /* TBILR */

        s->load[1] = value & 0xffff;

        break;

    case 0x30: /* TAMARCHR */

        s->match[0] = value & 0xffff;

        if (s->config < 4) {

            s->match[1] = value >> 16;

        }

        break;

    case 0x34: /* TBMATCHR */

        s->match[1] = value >> 16;

        break;

    case 0x38: /* TAPR */

        s->prescale[0] = value;

        break;

    case 0x3c: /* TBPR */

        s->prescale[1] = value;

        break;

    case 0x40: /* TAPMR */

        s->match_prescale[0] = value;

        break;

    case 0x44: /* TBPMR */

        s->match_prescale[0] = value;

        break;

    default:

        cpu_abort(cpu_single_env, "gptm_write: Bad offset 0x%x\n", (int)offset);

    }

    gptm_update_irq(s);

}

static CPUReadMemoryFunc *gptm_readfn[] = {

   gptm_read,

   gptm_read,

   gptm_read

};

static CPUWriteMemoryFunc *gptm_writefn[] = {

   gptm_write,

   gptm_write,

   gptm_write

};

static void stellaris_gptm_init(uint32_t base, qemu_irq irq, qemu_irq trigger)

{

    int iomemtype;

    gptm_state *s;

    s = (gptm_state *)qemu_mallocz(sizeof(gptm_state));

    s->base = base;

    s->irq = irq;

    s->trigger = trigger;

    s->opaque[0] = s->opaque[1] = s;

    iomemtype = cpu_register_io_memory(0, gptm_readfn,

                                       gptm_writefn, s);

    cpu_register_physical_memory(base, 0x00001000, iomemtype);

    s->timer[0] = qemu_new_timer(vm_clock, gptm_tick, &s->opaque[0]);

    s->timer[1] = qemu_new_timer(vm_clock, gptm_tick, &s->opaque[1]);

    /* ??? Save/restore.  */

}

/* System controller.  */

typedef struct {

    uint32_t base;

    uint32_t pborctl;

    uint32_t ldopctl;

    uint32_t int_status;

    uint32_t int_mask;

    uint32_t resc;

    uint32_t rcc;

    uint32_t rcgc[3];

    uint32_t scgc[3];

    uint32_t dcgc[3];

    uint32_t clkvclr;

    uint32_t ldoarst;

    uint32_t user0;

    uint32_t user1;

    qemu_irq irq;

    stellaris_board_info *board;

} ssys_state;

static void ssys_update(ssys_state *s)

{

  qemu_set_irq(s->irq, (s->int_status & s->int_mask) != 0);

}

static uint32_t pllcfg_sandstorm[16] = {

    0x31c0, /* 1 Mhz */

    0x1ae0, /* 1.8432 Mhz */

    0x18c0, /* 2 Mhz */

    0xd573, /* 2.4576 Mhz */

    0x37a6, /* 3.57954 Mhz */

    0x1ae2, /* 3.6864 Mhz */

    0x0c40, /* 4 Mhz */

    0x98bc, /* 4.906 Mhz */

    0x935b, /* 4.9152 Mhz */

    0x09c0, /* 5 Mhz */

    0x4dee, /* 5.12 Mhz */

    0x0c41, /* 6 Mhz */

    0x75db, /* 6.144 Mhz */

    0x1ae6, /* 7.3728 Mhz */

    0x0600, /* 8 Mhz */

    0x585b /* 8.192 Mhz */

};

static uint32_t pllcfg_fury[16] = {

    0x3200, /* 1 Mhz */

    0x1b20, /* 1.8432 Mhz */

    0x1900, /* 2 Mhz */

    0xf42b, /* 2.4576 Mhz */

    0x37e3, /* 3.57954 Mhz */

    0x1b21, /* 3.6864 Mhz */

    0x0c80, /* 4 Mhz */

    0x98ee, /* 4.906 Mhz */

    0xd5b4, /* 4.9152 Mhz */

    0x0a00, /* 5 Mhz */

    0x4e27, /* 5.12 Mhz */

    0x1902, /* 6 Mhz */

    0xec1c, /* 6.144 Mhz */

    0x1b23, /* 7.3728 Mhz */

    0x0640, /* 8 Mhz */

    0xb11c /* 8.192 Mhz */

};

static uint32_t ssys_read(void *opaque, target_phys_addr_t offset)

{

    ssys_state *s = (ssys_state *)opaque;

    offset -= s->base;

    switch (offset) {

    case 0x000: /* DID0 */

        return s->board->did0;

    case 0x004: /* DID1 */

        return s->board->did1;

    case 0x008: /* DC0 */

        return s->board->dc0;

    case 0x010: /* DC1 */

        return s->board->dc1;

    case 0x014: /* DC2 */

        return s->board->dc2;

    case 0x018: /* DC3 */

        return s->board->dc3;

    case 0x01c: /* DC4 */

        return s->board->dc4;

    case 0x030: /* PBORCTL */

        return s->pborctl;

    case 0x034: /* LDOPCTL */

        return s->ldopctl;

    case 0x040: /* SRCR0 */

        return 0;

    case 0x044: /* SRCR1 */

        return 0;

    case 0x048: /* SRCR2 */

        return 0;

    case 0x050: /* RIS */

        return s->int_status;

    case 0x054: /* IMC */

        return s->int_mask;

    case 0x058: /* MISC */

        return s->int_status & s->int_mask;

    case 0x05c: /* RESC */

        return s->resc;

    case 0x060: /* RCC */

        return s->rcc;

    case 0x064: /* PLLCFG */

        {

            int xtal;

            xtal = (s->rcc >> 6) & 0xf;

            if (s->board->did0 & (1 << 16)) {

                return pllcfg_fury[xtal];

            } else {

                return pllcfg_sandstorm[xtal];

            }

        }

    case 0x100: /* RCGC0 */

        return s->rcgc[0];

    case 0x104: /* RCGC1 */

        return s->rcgc[1];

    case 0x108: /* RCGC2 */

        return s->rcgc[2];

    case 0x110: /* SCGC0 */

        return s->scgc[0];

    case 0x114: /* SCGC1 */

        return s->scgc[1];

    case 0x118: /* SCGC2 */

        return s->scgc[2];

    case 0x120: /* DCGC0 */

        return s->dcgc[0];

    case 0x124: /* DCGC1 */

        return s->dcgc[1];

    case 0x128: /* DCGC2 */

        return s->dcgc[2];

    case 0x150: /* CLKVCLR */

        return s->clkvclr;

    case 0x160: /* LDOARST */

        return s->ldoarst;

    case 0x1e0: /* USER0 */

        return s->user0;

    case 0x1e4: /* USER1 */

        return s->user1;

    default:

        cpu_abort(cpu_single_env, "ssys_read: Bad offset 0x%x\n", (int)offset);

        return 0;

    }

}

static void ssys_write(void *opaque, target_phys_addr_t offset, uint32_t value)

{

    ssys_state *s = (ssys_state *)opaque;

    offset -= s->base;

    switch (offset) {

    case 0x030: /* PBORCTL */

        s->pborctl = value & 0xffff;

        break;

    case 0x034: /* LDOPCTL */

        s->ldopctl = value & 0x1f;

        break;

    case 0x040: /* SRCR0 */

    case 0x044: /* SRCR1 */

    case 0x048: /* SRCR2 */

        fprintf(stderr, "Peripheral reset not implemented\n");

        break;

    case 0x054: /* IMC */

        s->int_mask = value & 0x7f;

        break;

    case 0x058: /* MISC */

        s->int_status &= ~value;

        break;

    case 0x05c: /* RESC */

        s->resc = value & 0x3f;

        break;

    case 0x060: /* RCC */

        if ((s->rcc & (1 << 13)) != 0 && (value & (1 << 13)) == 0) {

            /* PLL enable.  */

            s->int_status |= (1 << 6);

        }

        s->rcc = value;

        system_clock_scale = 5 * (((s->rcc >> 23) & 0xf) + 1);

        break;

    case 0x100: /* RCGC0 */

        s->rcgc[0] = value;

        break;

    case 0x104: /* RCGC1 */

        s->rcgc[1] = value;

        break;

    case 0x108: /* RCGC2 */

        s->rcgc[2] = value;

        break;

    case 0x110: /* SCGC0 */

        s->scgc[0] = value;

        break;

    case 0x114: /* SCGC1 */

        s->scgc[1] = value;

        break;

    case 0x118: /* SCGC2 */

        s->scgc[2] = value;

        break;

    case 0x120: /* DCGC0 */

        s->dcgc[0] = value;

        break;

    case 0x124: /* DCGC1 */

        s->dcgc[1] = value;

        break;

    case 0x128: /* DCGC2 */

        s->dcgc[2] = value;

        break;

    case 0x150: /* CLKVCLR */

        s->clkvclr = value;

        break;

    case 0x160: /* LDOARST */

        s->ldoarst = value;

        break;

    default:

        cpu_abort(cpu_single_env, "ssys_write: Bad offset 0x%x\n", (int)offset);

    }

    ssys_update(s);

}

static CPUReadMemoryFunc *ssys_readfn[] = {

   ssys_read,

   ssys_read,

   ssys_read

};

static CPUWriteMemoryFunc *ssys_writefn[] = {

   ssys_write,

   ssys_write,

   ssys_write

};

static void ssys_reset(void *opaque)

{

    ssys_state *s = (ssys_state *)opaque;

    s->pborctl = 0x7ffd;

    s->rcc = 0x078e3ac0;

    s->rcgc[0] = 1;

    s->scgc[0] = 1;

    s->dcgc[0] = 1;

}

static void stellaris_sys_init(uint32_t base, qemu_irq irq,

                               stellaris_board_info * board,

                               uint8_t *macaddr)

{

    int iomemtype;

    ssys_state *s;

    s = (ssys_state *)qemu_mallocz(sizeof(ssys_state));

    s->base = base;

    s->irq = irq;

    s->board = board;

    /* Most devices come preprogrammed with a MAC address in the user data. */

    s->user0 = macaddr[0] | (macaddr[1] << 8) | (macaddr[2] << 16);

    s->user1 = macaddr[3] | (macaddr[4] << 8) | (macaddr[5] << 16);

    iomemtype = cpu_register_io_memory(0, ssys_readfn,

                                       ssys_writefn, s);

    cpu_register_physical_memory(base, 0x00001000, iomemtype);

    ssys_reset(s);

    /* ??? Save/restore.  */

}

/* I2C controller.  */

typedef struct {

    i2c_bus *bus;

    qemu_irq irq;

    uint32_t base;

    uint32_t msa;

    uint32_t mcs;

    uint32_t mdr;

    uint32_t mtpr;

    uint32_t mimr;

    uint32_t mris;

    uint32_t mcr;

} stellaris_i2c_state;

#define STELLARIS_I2C_MCS_BUSY    0x01

#define STELLARIS_I2C_MCS_ERROR   0x02

#define STELLARIS_I2C_MCS_ADRACK  0x04

#define STELLARIS_I2C_MCS_DATACK  0x08

#define STELLARIS_I2C_MCS_ARBLST  0x10

#define STELLARIS_I2C_MCS_IDLE    0x20

#define STELLARIS_I2C_MCS_BUSBSY  0x40

static uint32_t stellaris_i2c_read(void *opaque, target_phys_addr_t offset)

{

    stellaris_i2c_state *s = (stellaris_i2c_state *)opaque;

    offset -= s->base;

    switch (offset) {

    case 0x00: /* MSA */

        return s->msa;

    case 0x04: /* MCS */

        /* We don't emulate timing, so the controller is never busy.  */

        return s->mcs | STELLARIS_I2C_MCS_IDLE;

    case 0x08: /* MDR */

        return s->mdr;

    case 0x0c: /* MTPR */

        return s->mtpr;

    case 0x10: /* MIMR */

        return s->mimr;

    case 0x14: /* MRIS */

        return s->mris;

    case 0x18: /* MMIS */

        return s->mris & s->mimr;

    case 0x20: /* MCR */

        return s->mcr;

    default:

        cpu_abort(cpu_single_env, "strllaris_i2c_read: Bad offset 0x%x\n",

                  (int)offset);

        return 0;

    }

}

static void stellaris_i2c_update(stellaris_i2c_state *s)

{

    int level;

    level = (s->mris & s->mimr) != 0;

    qemu_set_irq(s->irq, level);

}

static void stellaris_i2c_write(void *opaque, target_phys_addr_t offset,

                                uint32_t value)

{

    stellaris_i2c_state *s = (stellaris_i2c_state *)opaque;

    offset -= s->base;

    switch (offset) {

    case 0x00: /* MSA */

        s->msa = value & 0xff;

        break;

    case 0x04: /* MCS */

        if ((s->mcr & 0x10) == 0) {

            /* Disabled.  Do nothing.  */

            break;

        }

        /* Grab the bus if this is starting a transfer.  */

        if ((value & 2) && (s->mcs & STELLARIS_I2C_MCS_BUSBSY) == 0) {

            if (i2c_start_transfer(s->bus, s->msa >> 1, s->msa & 1)) {

                s->mcs |= STELLARIS_I2C_MCS_ARBLST;

            } else {

                s->mcs &= ~STELLARIS_I2C_MCS_ARBLST;

                s->mcs |= STELLARIS_I2C_MCS_BUSBSY;

            }

        }

        /* If we don't have the bus then indicate an error.  */

        if (!i2c_bus_busy(s->bus)

                || (s->mcs & STELLARIS_I2C_MCS_BUSBSY) == 0) {

            s->mcs |= STELLARIS_I2C_MCS_ERROR;

            break;

        }

        s->mcs &= ~STELLARIS_I2C_MCS_ERROR;

        if (value & 1) {

            /* Transfer a byte.  */

            /* TODO: Handle errors.  */

            if (s->msa & 1) {

                /* Recv */

                s->mdr = i2c_recv(s->bus) & 0xff;

            } else {

                /* Send */

                i2c_send(s->bus, s->mdr);

            }

            /* Raise an interrupt.  */

            s->mris |= 1;

        }

        if (value & 4) {

            /* Finish transfer.  */

            i2c_end_transfer(s->bus);

            s->mcs &= ~STELLARIS_I2C_MCS_BUSBSY;

        }

        break;

    case 0x08: /* MDR */

        s->mdr = value & 0xff;

        break;

    case 0x0c: /* MTPR */

        s->mtpr = value & 0xff;

        break;

    case 0x10: /* MIMR */

        s->mimr = 1;

        break;

    case 0x1c: /* MICR */

        s->mris &= ~value;

        break;

    case 0x20: /* MCR */

        if (value & 1)

            cpu_abort(cpu_single_env,

                      "stellaris_i2c_write: Loopback not implemented\n");

        if (value & 0x20)

            cpu_abort(cpu_single_env,

                      "stellaris_i2c_write: Slave mode not implemented\n");

        s->mcr = value & 0x31;

        break;

    default:

        cpu_abort(cpu_single_env, "stellaris_i2c_write: Bad offset 0x%x\n",

                  (int)offset);

    }

    stellaris_i2c_update(s);

}

static void stellaris_i2c_reset(stellaris_i2c_state *s)

{

    if (s->mcs & STELLARIS_I2C_MCS_BUSBSY)

        i2c_end_transfer(s->bus);

    s->msa = 0;

    s->mcs = 0;

    s->mdr = 0;

    s->mtpr = 1;

    s->mimr = 0;

    s->mris = 0;

    s->mcr = 0;

    stellaris_i2c_update(s);

}

static CPUReadMemoryFunc *stellaris_i2c_readfn[] = {

   stellaris_i2c_read,

   stellaris_i2c_read,

   stellaris_i2c_read

};

static CPUWriteMemoryFunc *stellaris_i2c_writefn[] = {

   stellaris_i2c_write,

   stellaris_i2c_write,

   stellaris_i2c_write

};

static void stellaris_i2c_init(uint32_t base, qemu_irq irq, i2c_bus *bus)

{

    stellaris_i2c_state *s;

    int iomemtype;

    s = (stellaris_i2c_state *)qemu_mallocz(sizeof(stellaris_i2c_state));

    s->base = base;

    s->irq = irq;

    s->bus = bus;

    iomemtype = cpu_register_io_memory(0, stellaris_i2c_readfn,

                                       stellaris_i2c_writefn, s);

    cpu_register_physical_memory(base, 0x00001000, iomemtype);

    /* ??? For now we only implement the master interface.  */

    stellaris_i2c_reset(s);

}

/* Analogue to Digital Converter.  This is only partially implemented,

   enough for applications that use a combined ADC and timer tick.  */

#define STELLARIS_ADC_EM_CONTROLLER 0

#define STELLARIS_ADC_EM_COMP       1

#define STELLARIS_ADC_EM_EXTERNAL   4

#define STELLARIS_ADC_EM_TIMER      5

#define STELLARIS_ADC_EM_PWM0       6

#define STELLARIS_ADC_EM_PWM1       7

#define STELLARIS_ADC_EM_PWM2       8

#define STELLARIS_ADC_FIFO_EMPTY    0x0100

#define STELLARIS_ADC_FIFO_FULL     0x1000

typedef struct

{

    uint32_t base;

    uint32_t actss;

    uint32_t ris;

    uint32_t im;

    uint32_t emux;

    uint32_t ostat;

    uint32_t ustat;

    uint32_t sspri;

    uint32_t sac;

    struct {

        uint32_t state;

        uint32_t data[16];

    } fifo[4];

    uint32_t ssmux[4];

    uint32_t ssctl[4];

    qemu_irq irq;

} stellaris_adc_state;

static uint32_t stellaris_adc_fifo_read(stellaris_adc_state *s, int n)

{

    int tail;

    tail = s->fifo[n].state & 0xf;

    if (s->fifo[n].state & STELLARIS_ADC_FIFO_EMPTY) {

        s->ustat |= 1 << n;

    } else {

        s->fifo[n].state = (s->fifo[n].state & ~0xf) | ((tail + 1) & 0xf);

        s->fifo[n].state &= ~STELLARIS_ADC_FIFO_FULL;

        if (tail + 1 == ((s->fifo[n].state >> 4) & 0xf))

            s->fifo[n].state |= STELLARIS_ADC_FIFO_EMPTY;

    }

    return s->fifo[n].data[tail];

}

static void stellaris_adc_fifo_write(stellaris_adc_state *s, int n,

                                     uint32_t value)

{

    int head;

    head = (s->fifo[n].state >> 4) & 0xf;

    if (s->fifo[n].state & STELLARIS_ADC_FIFO_FULL) {

        s->ostat |= 1 << n;

        return;

    }

    s->fifo[n].data[head] = value;

    head = (head + 1) & 0xf;

    s->fifo[n].state &= ~STELLARIS_ADC_FIFO_EMPTY;

    s->fifo[n].state = (s->fifo[n].state & ~0xf0) | (head << 4);

    if ((s->fifo[n].state & 0xf) == head)

        s->fifo[n].state |= STELLARIS_ADC_FIFO_FULL;

}

static void stellaris_adc_update(stellaris_adc_state *s)

{

    int level;

    level = (s->ris & s->im) != 0;

    qemu_set_irq(s->irq, level);

}

static void stellaris_adc_trigger(void *opaque, int irq, int level)

{

    stellaris_adc_state *s = (stellaris_adc_state *)opaque;

    /* Some applications use the ADC as a random number source, so introduce

       some variation into the signal.  */

    static uint32_t noise = 0;

    if ((s->actss & 1) == 0) {

        return;

    }

    noise = noise * 314159 + 1;

    /* ??? actual inputs not implemented.  Return an arbitrary value.  */

    stellaris_adc_fifo_write(s, 0, 0x200 + ((noise >> 16) & 7));

    s->ris |= 1;

    stellaris_adc_update(s);

}

static void stellaris_adc_reset(stellaris_adc_state *s)

{

    int n;

    for (n = 0; n < 4; n++) {

        s->ssmux[n] = 0;

        s->ssctl[n] = 0;

        s->fifo[n].state = STELLARIS_ADC_FIFO_EMPTY;

    }

}

static uint32_t stellaris_adc_read(void *opaque, target_phys_addr_t offset)