Texas Instruments ADS7846 ADC chip.

git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@2754 c046a42c-6fe2-441c-8c8c-71466251a162

1 files changed, 131 insertions, 0 deletions

diff --git a/hw/ads7846.c b/hw/ads7846.c
new file mode 100644
index 0000000..d63a915
--- /dev/null
+++ b/hw/ads7846.c
@@ -0,0 +1,131 @@
+/*
+ * TI ADS7846 chip emulation.
+ *
+ * Copyright (c) 2006 Openedhand Ltd.
+ * Written by Andrzej Zaborowski <balrog@zabor.org>
+ *
+ * This code is licensed under the GNU GPL v2.
+ */
+
+#include <vl.h>
+
+struct ads7846_state_s {
+    qemu_irq interrupt;
+
+    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)
+        qemu_set_irq(s->interrupt, 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(qemu_irq penirq)
+{
+    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->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;
+}