root / hw / ads7846.c @ 4118a970
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/*
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* TI ADS7846 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 GPL v2.
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*/
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#include <vl.h> |
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struct ads7846_state_s {
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qemu_irq interrupt; |
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int input[8]; |
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int pressure;
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int noise;
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int cycle;
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int output;
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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_SER (1 << 2) |
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#define CB_MODE (1 << 3) |
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#define CB_A0 (1 << 4) |
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#define CB_A1 (1 << 5) |
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#define CB_A2 (1 << 6) |
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#define CB_START (1 << 7) |
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#define X_AXIS_DMAX 3470 |
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#define X_AXIS_MIN 290 |
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#define Y_AXIS_DMAX 3450 |
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#define Y_AXIS_MIN 200 |
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#define ADS_VBAT 2000 |
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#define ADS_VAUX 2000 |
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#define ADS_TEMP0 2000 |
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#define ADS_TEMP1 3000 |
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#define ADS_XPOS(x, y) (X_AXIS_MIN + ((X_AXIS_DMAX * (x)) >> 15)) |
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#define ADS_YPOS(x, y) (Y_AXIS_MIN + ((Y_AXIS_DMAX * (y)) >> 15)) |
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#define ADS_Z1POS(x, y) 600 |
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#define ADS_Z2POS(x, y) (600 + 6000 / ADS_XPOS(x, y)) |
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static void ads7846_int_update(struct ads7846_state_s *s) |
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{ |
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if (s->interrupt)
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qemu_set_irq(s->interrupt, s->pressure == 0);
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} |
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uint32_t ads7846_read(void *opaque)
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{ |
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struct ads7846_state_s *s = (struct ads7846_state_s *) opaque; |
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return s->output;
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} |
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void ads7846_write(void *opaque, uint32_t value) |
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{ |
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struct ads7846_state_s *s = (struct ads7846_state_s *) opaque; |
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switch (s->cycle ++) {
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case 0: |
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if (!(value & CB_START)) {
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s->cycle = 0;
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break;
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} |
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s->output = s->input[(value >> 4) & 7]; |
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/* Imitate the ADC noise, some drivers expect this. */
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s->noise = (s->noise + 3) & 7; |
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switch ((value >> 4) & 7) { |
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case 1: s->output += s->noise ^ 2; break; |
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case 3: s->output += s->noise ^ 0; break; |
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case 4: s->output += s->noise ^ 7; break; |
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case 5: s->output += s->noise ^ 5; break; |
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} |
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if (value & CB_MODE)
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s->output >>= 4; /* 8 bits instead of 12 */ |
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break;
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case 1: |
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s->cycle = 0;
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break;
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} |
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} |
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static void ads7846_ts_event(void *opaque, |
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int x, int y, int z, int buttons_state) |
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{ |
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struct ads7846_state_s *s = opaque;
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if (buttons_state) {
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x = 0x7fff - x;
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s->input[1] = ADS_XPOS(x, y);
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s->input[3] = ADS_Z1POS(x, y);
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s->input[4] = ADS_Z2POS(x, y);
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s->input[5] = ADS_YPOS(x, y);
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} |
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if (s->pressure == !buttons_state) {
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s->pressure = !!buttons_state; |
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ads7846_int_update(s); |
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} |
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} |
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static void ads7846_save(QEMUFile *f, void *opaque) |
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{ |
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struct ads7846_state_s *s = (struct ads7846_state_s *) opaque; |
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int i;
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for (i = 0; i < 8; i ++) |
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qemu_put_be32(f, s->input[i]); |
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qemu_put_be32(f, s->noise); |
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qemu_put_be32(f, s->cycle); |
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qemu_put_be32(f, s->output); |
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} |
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static int ads7846_load(QEMUFile *f, void *opaque, int version_id) |
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{ |
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struct ads7846_state_s *s = (struct ads7846_state_s *) opaque; |
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int i;
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for (i = 0; i < 8; i ++) |
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s->input[i] = qemu_get_be32(f); |
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s->noise = qemu_get_be32(f); |
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s->cycle = qemu_get_be32(f); |
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s->output = qemu_get_be32(f); |
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s->pressure = 0;
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ads7846_int_update(s); |
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return 0; |
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} |
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static int ads7846_iid = 0; |
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struct ads7846_state_s *ads7846_init(qemu_irq penirq)
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{ |
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struct ads7846_state_s *s;
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s = (struct ads7846_state_s *)
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qemu_mallocz(sizeof(struct ads7846_state_s)); |
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memset(s, 0, sizeof(struct ads7846_state_s)); |
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s->interrupt = penirq; |
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s->input[0] = ADS_TEMP0; /* TEMP0 */ |
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s->input[2] = ADS_VBAT; /* VBAT */ |
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s->input[6] = ADS_VAUX; /* VAUX */ |
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s->input[7] = ADS_TEMP1; /* TEMP1 */ |
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/* We want absolute coordinates */
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qemu_add_mouse_event_handler(ads7846_ts_event, s, 1,
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"QEMU ADS7846-driven Touchscreen");
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ads7846_int_update(s); |
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register_savevm("ads7846", ads7846_iid ++, 0, |
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ads7846_save, ads7846_load, s); |
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return s;
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} |