Samus: Support capsense input as keyboard events.

This is experimental for now; the capsense chip simply reports its buttons
as the number keys on the keyboard (1-8).

BUG=chrome-os-partner:23382
BRANCH=samus,ToT
TEST=manual

To test, you'll need a reworked and correctly programmed capsense module.
Boot the system, and switch to VT2. Touch the capsense bar and you'll see
the input appear on the console as though you were typing numbers.

Note that the capsense hardware is still buggy. Refer to the bug for
workarounds.

Change-Id: I4c3a8b70b8197ffd538c38c59c9336383365afa7
Signed-off-by: Bill Richardson <wfrichar@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/185434
Reviewed-by: Randall Spangler <rspangler@chromium.org>
Reviewed-by: Dave Parker <dparker@chromium.org>

1 files changed, 86 insertions, 0 deletions

diff --git a/common/capsense.c b/common/capsense.c
new file mode 100644
index 0000000000..e0df749933
--- /dev/null
+++ b/common/capsense.c
@@ -0,0 +1,86 @@
+/* Copyright (c) 2014 The Chromium OS Authors. All rights reserved.
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#include "common.h"
+#include "console.h"
+#include "gpio.h"
+#include "hooks.h"
+#include "i2c.h"
+#include "keyboard_protocol.h"
+#include "timer.h"
+
+/* Console output macro */
+#define CPRINTF(format, args...) cprintf(CC_KEYBOARD, format, ## args)
+
+#define CAPSENSE_I2C_ADDR 0x08
+#define CAPSENSE_MASK_BITS 8
+#define CAPSENSE_POLL_INTERVAL (20 * MSEC)
+
+static int capsense_read_bitmask(void)
+{
+	int rv;
+	uint8_t val = 0;
+
+	i2c_lock(I2C_PORT_CAPSENSE, 1);
+	rv = i2c_xfer(I2C_PORT_CAPSENSE, CAPSENSE_I2C_ADDR,
+		      0, 0, &val, 1, I2C_XFER_SINGLE);
+	i2c_lock(I2C_PORT_CAPSENSE, 0);
+
+	if (rv)
+		CPRINTF("[%T %s failed: error %d]\n", __func__, rv);
+
+	return val;
+}
+
+static void capsense_init(void)
+{
+	gpio_enable_interrupt(GPIO_CAPSENSE_INT_L);
+}
+DECLARE_HOOK(HOOK_INIT, capsense_init, HOOK_PRIO_DEFAULT);
+
+/*
+ * Keep checking polling the capsense until all the buttons are released.
+ * We're not worrying about debouncing, since the capsense module should do
+ * that for us.
+ */
+static void capsense_change_deferred(void)
+{
+	static uint8_t cur_val;
+	uint8_t new_val;
+	int i, n, c;
+
+	new_val = capsense_read_bitmask();
+	if (new_val != cur_val) {
+		CPRINTF("[%T capsense 0x%02x: ", new_val);
+		for (i = 0; i < CAPSENSE_MASK_BITS; i++) {
+			/* See what changed */
+			n = (new_val >> i) & 0x01;
+			c = (cur_val >> i) & 0x01;
+			CPRINTF("%s", n ? " X " : " _ ");
+			if (n == c)
+				continue;
+#ifdef HAS_TASK_KEYPROTO
+			/* Treat it as a keyboard event. */
+			keyboard_update_button(i + KEYBOARD_BUTTON_CAPSENSE_1,
+					       n);
+#endif
+		}
+		CPRINTF("]\n");
+		cur_val = new_val;
+	}
+
+	if (cur_val)
+		hook_call_deferred(capsense_change_deferred,
+				   CAPSENSE_POLL_INTERVAL);
+}
+DECLARE_DEFERRED(capsense_change_deferred);
+
+/*
+ * Somebody's poking at us.
+ */
+void capsense_interrupt(enum gpio_signal signal)
+{
+	hook_call_deferred(capsense_change_deferred, 0);
+}