This is an ADC chip with eight inputs usually used for power
management (battery current measurements) on small systems and a
touchscreen controller. This chip or similar ones (7845 etc) are seen
a lot in all kinds of PDAs.
Cheers,
Andrew
From f6be7abd757e49e67b81847634c1075e222be0bc Mon Sep 17 00:00:00 2001
From: Andrzej Zaborowski <[EMAIL PROTECTED]>
Date: Fri, 16 Mar 2007 16:53:08 +0100
Subject: [PATCH] Texas Instruments ADS7846 ADC chip.
---
hw/ads7846.c | 134 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
vl.h | 8 ++++
2 files changed, 142 insertions(+), 0 deletions(-)
diff --git a/hw/ads7846.c b/hw/ads7846.c
new file mode 100644
index 0000000..3297b7b
--- /dev/null
+++ b/hw/ads7846.c
@@ -0,0 +1,134 @@
+/*
+ * TI ADS7846 chip emulation.
+ *
+ * Copyright (c) 2006 Openedhand Ltd.
+ * Written by Andrzej Zaborowski <[EMAIL PROTECTED]>
+ *
+ * This code is licensed under the GNU GPL v2.
+ */
+
+#include <vl.h>
+
+struct ads7846_state_s {
+ void (*interrupt)(void *opaque, int level);
+ void *opaque;
+
+ int input[8];
+ int pressure;
+ int noise;
+
+ int cycle;
+ int output;
+};
+
+/* Control-byte bitfields */
+#define CB_PD0 (1 << 0)
+#define CB_PD1 (1 << 1)
+#define CB_SER (1 << 2)
+#define CB_MODE (1 << 3)
+#define CB_A0 (1 << 4)
+#define CB_A1 (1 << 5)
+#define CB_A2 (1 << 6)
+#define CB_START (1 << 7)
+
+#define X_AXIS_DMAX 3680
+#define X_AXIS_MIN 150
+#define Y_AXIS_DMAX 3640
+#define Y_AXIS_MIN 190
+
+#define ADS_VBAT 2000
+#define ADS_VAUX 2000
+#define ADS_TEMP0 2000
+#define ADS_TEMP1 3000
+#define ADS_XPOS(x, y) (X_AXIS_MIN + ((X_AXIS_DMAX * (x)) >> 15))
+#define ADS_YPOS(x, y) (Y_AXIS_MIN + ((Y_AXIS_DMAX * (y)) >> 15))
+#define ADS_Z1POS(x, y) 600
+#define ADS_Z2POS(x, y) (600 + 6000 / ADS_XPOS(x, y))
+
+static void ads7846_int_update(struct ads7846_state_s *s)
+{
+ if (s->interrupt)
+ s->interrupt(s->opaque, s->pressure == 0);
+}
+
+uint32_t ads7846_read(void *opaque)
+{
+ struct ads7846_state_s *s = (struct ads7846_state_s *) opaque;
+
+ return s->output;
+}
+
+void ads7846_write(void *opaque, uint32_t value)
+{
+ struct ads7846_state_s *s = (struct ads7846_state_s *) opaque;
+
+ switch (s->cycle ++) {
+ case 0:
+ if (!(value & CB_START)) {
+ s->cycle = 0;
+ break;
+ }
+
+ s->output = s->input[(value >> 4) & 7];
+
+ /* Imitate the ADC noise, some drivers expect this. */
+ s->noise = (s->noise + 3) & 7;
+ switch ((value >> 4) & 7) {
+ case 1: s->output += s->noise ^ 2; break;
+ case 3: s->output += s->noise ^ 0; break;
+ case 4: s->output += s->noise ^ 7; break;
+ case 5: s->output += s->noise ^ 5; break;
+ }
+
+ if (value & CB_MODE)
+ s->output >>= 4; /* 8 bits instead of 12 */
+
+ break;
+ case 1:
+ s->cycle = 0;
+ break;
+ }
+}
+
+static void ads7846_ts_event(void *opaque,
+ int x, int y, int z, int buttons_state)
+{
+ struct ads7846_state_s *s = opaque;
+
+ if (buttons_state) {
+ s->input[1] = ADS_YPOS(x, y);
+ s->input[3] = ADS_Z1POS(x, y);
+ s->input[4] = ADS_Z2POS(x, y);
+ s->input[5] = ADS_XPOS(x, y);
+ }
+
+ if (s->pressure == !buttons_state) {
+ s->pressure = !!buttons_state;
+
+ ads7846_int_update(s);
+ }
+}
+
+struct ads7846_state_s *ads7846_init(
+ void (*penirq)(void *opaque, int level), void *opaque)
+{
+ struct ads7846_state_s *s;
+ s = (struct ads7846_state_s *)
+ qemu_mallocz(sizeof(struct ads7846_state_s));
+ memset(s, 0, sizeof(struct ads7846_state_s));
+
+ s->interrupt = penirq;
+ s->opaque = opaque;
+
+ s->input[0] = ADS_TEMP0; /* TEMP0 */
+ s->input[2] = ADS_VBAT; /* VBAT */
+ s->input[6] = ADS_VAUX; /* VAUX */
+ s->input[7] = ADS_TEMP1; /* TEMP1 */
+
+ /* We want absolute coordinates */
+ qemu_add_mouse_event_handler(ads7846_ts_event, s, 1,
+ "QEMU ADS7846-driven Touchscreen");
+
+ ads7846_int_update(s);
+ return s;
+}
diff --git a/vl.h b/vl.h
index 7c88c72..2f2e340 100644
--- a/vl.h
+++ b/vl.h
@@ -1414,6 +1414,14 @@ uint8_t nand_getio(struct nand_flash_s *s);
#include "ecc.h"
+
+/* ads7846.c */
+struct ads7846_state_s;
+uint32_t ads7846_read(void *opaque);
+void ads7846_write(void *opaque, uint32_t value);
+struct ads7846_state_s *ads7846_init(
+ void (*penirq)(void *opaque, int level), void *opaque);
+
/* PCMCIA/Cardbus */
struct pcmcia_socket_s {
--
1.4.4.3
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