137 lines
2.7 KiB
C
137 lines
2.7 KiB
C
/*
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* Maxim MAX1110/1111 ADC chip emulation.
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*
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* Copyright (c) 2006 Openedhand Ltd.
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* Written by Andrzej Zaborowski <balrog@zabor.org>
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*
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* This code is licensed under the GNU GPLv2.
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*/
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#include <vl.h>
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struct max111x_s {
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qemu_irq interrupt;
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uint8_t tb1, rb2, rb3;
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int cycle;
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int input[8];
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int inputs, com;
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};
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/* Control-byte bitfields */
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#define CB_PD0 (1 << 0)
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#define CB_PD1 (1 << 1)
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#define CB_SGL (1 << 2)
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#define CB_UNI (1 << 3)
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#define CB_SEL0 (1 << 4)
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#define CB_SEL1 (1 << 5)
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#define CB_SEL2 (1 << 6)
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#define CB_START (1 << 7)
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#define CHANNEL_NUM(v, b0, b1, b2) \
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((((v) >> (2 + (b0))) & 4) | \
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(((v) >> (3 + (b1))) & 2) | \
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(((v) >> (4 + (b2))) & 1))
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uint32_t max111x_read(void *opaque)
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{
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struct max111x_s *s = (struct max111x_s *) opaque;
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if (!s->tb1)
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return 0;
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switch (s->cycle ++) {
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case 1:
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return s->rb2;
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case 2:
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return s->rb3;
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}
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return 0;
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}
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/* Interpret a control-byte */
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void max111x_write(void *opaque, uint32_t value)
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{
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struct max111x_s *s = (struct max111x_s *) opaque;
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int measure, chan;
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/* Ignore the value if START bit is zero */
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if (!(value & CB_START))
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return;
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s->cycle = 0;
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if (!(value & CB_PD1)) {
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s->tb1 = 0;
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return;
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}
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s->tb1 = value;
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if (s->inputs == 8)
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chan = CHANNEL_NUM(value, 1, 0, 2);
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else
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chan = CHANNEL_NUM(value & ~CB_SEL0, 0, 1, 2);
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if (value & CB_SGL)
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measure = s->input[chan] - s->com;
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else
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measure = s->input[chan] - s->input[chan ^ 1];
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if (!(value & CB_UNI))
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measure ^= 0x80;
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s->rb2 = (measure >> 2) & 0x3f;
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s->rb3 = (measure << 6) & 0xc0;
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if (s->interrupt)
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qemu_irq_raise(s->interrupt);
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}
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static struct max111x_s *max111x_init(qemu_irq cb)
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{
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struct max111x_s *s;
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s = (struct max111x_s *)
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qemu_mallocz(sizeof(struct max111x_s));
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memset(s, 0, sizeof(struct max111x_s));
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s->interrupt = cb;
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/* TODO: add a user interface for setting these */
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s->input[0] = 0xf0;
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s->input[1] = 0xe0;
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s->input[2] = 0xd0;
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s->input[3] = 0xc0;
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s->input[4] = 0xb0;
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s->input[5] = 0xa0;
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s->input[6] = 0x90;
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s->input[7] = 0x80;
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s->com = 0;
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return s;
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}
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struct max111x_s *max1110_init(qemu_irq cb)
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{
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struct max111x_s *s = max111x_init(cb);
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s->inputs = 8;
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return s;
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}
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struct max111x_s *max1111_init(qemu_irq cb)
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{
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struct max111x_s *s = max111x_init(cb);
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s->inputs = 4;
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return s;
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}
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void max111x_set_input(struct max111x_s *s, int line, uint8_t value)
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{
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if (line >= s->inputs) {
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printf("%s: There's no input %i\n", __FUNCTION__, line);
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return;
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}
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s->input[line] = value;
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}
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