Input: cyttsp5 - implement proper sleep and wakeup procedures

The touchscreen can be put into a deep sleep state that prevents it from
emitting touch irqs. Put the touchscreen into deep sleep during suspend
if it is not marked as a wakeup source.

This also fixes a problem with the touchscreen getting unresponsive after
system resume when a falling edge trigger is used for the interrupt.
When left on during suspend, the touchscreen would pull the interrupt
line down in response to touch events, leaving the interrupt effectively
disabled after resume.
Signed-off-by: Maximilian Weigand <mweigand@mweigand.net>
Reviewed-by: Alistair Francis <alistair@alistair23.me>
Link: https://lore.kernel.org/r/20230504120316.408687-2-mweigand2017@gmail.comSigned-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

drivers/input/touchscreen/cyttsp5.c

@@ -43,6 +43,7 @@
 #define HID_DESC_REG				0x1
 #define HID_INPUT_REG				0x3
 #define HID_OUTPUT_REG				0x4
+#define HID_COMMAND_REG				0x5
 
 #define REPORT_ID_TOUCH				0x1
 #define REPORT_ID_BTN				0x3
@@ -68,6 +69,7 @@
 #define HID_APP_OUTPUT_REPORT_ID		0x2F
 #define HID_BL_RESPONSE_REPORT_ID		0x30
 #define HID_BL_OUTPUT_REPORT_ID			0x40
+#define HID_RESPONSE_REPORT_ID			0xF0
 
 #define HID_OUTPUT_RESPONSE_REPORT_OFFSET	2
 #define HID_OUTPUT_RESPONSE_CMD_OFFSET		4
@@ -78,9 +80,15 @@
 #define HID_SYSINFO_BTN_MASK			GENMASK(7, 0)
 #define HID_SYSINFO_MAX_BTN			8
 
+#define HID_CMD_SET_POWER			0x8
+
+#define HID_POWER_ON				0x0
+#define HID_POWER_SLEEP				0x1
+
 #define CY_HID_OUTPUT_TIMEOUT_MS		200
 #define CY_HID_OUTPUT_GET_SYSINFO_TIMEOUT_MS	3000
 #define CY_HID_GET_HID_DESCRIPTOR_TIMEOUT_MS	4000
+#define CY_HID_SET_POWER_TIMEOUT		500
 
 /* maximum number of concurrent tracks */
 #define TOUCH_REPORT_SIZE			10
@@ -100,6 +108,14 @@
 #define TOUCH_REPORT_USAGE_PG_MIN		0xFF010063
 #define TOUCH_COL_USAGE_PG			0x000D0022
 
+#define SET_CMD_LOW(byte, bits) \
+	((byte) = (((byte) & 0xF0) | ((bits) & 0x0F)))
+#define SET_CMD_HIGH(byte, bits)\
+	((byte) = (((byte) & 0x0F) | ((bits) & 0xF0)))
+#define SET_CMD_OPCODE(byte, opcode) SET_CMD_LOW(byte, opcode)
+#define SET_CMD_REPORT_TYPE(byte, type) SET_CMD_HIGH(byte, ((type) << 4))
+#define SET_CMD_REPORT_ID(byte, id) SET_CMD_LOW(byte, id)
+
 /* System Information interface definitions */
 struct cyttsp5_sensing_conf_data_dev {
 	u8 electrodes_x;
@@ -556,6 +572,40 @@ static int cyttsp5_hid_output_get_sysinfo(struct cyttsp5 *ts)
 	return cyttsp5_get_sysinfo_regs(ts);
 }
 
+static int cyttsp5_power_control(struct cyttsp5 *ts, bool on)
+{
+	u8 state = on ? HID_POWER_ON : HID_POWER_SLEEP;
+	u8 cmd[2] = { 0 };
+	int rc;
+
+	SET_CMD_REPORT_TYPE(cmd[0], 0);
+	SET_CMD_REPORT_ID(cmd[0], HID_POWER_SLEEP);
+	SET_CMD_OPCODE(cmd[1], HID_CMD_SET_POWER);
+
+	rc = cyttsp5_write(ts, HID_COMMAND_REG, cmd, sizeof(cmd));
+	if (rc) {
+		dev_err(ts->dev, "Failed to write power command %d", rc);
+		return rc;
+	}
+
+	rc = wait_for_completion_interruptible_timeout(&ts->cmd_done,
+				msecs_to_jiffies(CY_HID_SET_POWER_TIMEOUT));
+	if (rc <= 0) {
+		dev_err(ts->dev, "HID power cmd execution timed out\n");
+		return -ETIMEDOUT;
+	}
+
+	if (ts->response_buf[2] != HID_RESPONSE_REPORT_ID ||
+	    (ts->response_buf[3] & 0x03) != state ||
+	    (ts->response_buf[4] & 0x0f) != HID_CMD_SET_POWER) {
+		dev_err(ts->dev, "Validation of the %s response failed\n",
+			on ? "wakeup" : "sleep");
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
 static int cyttsp5_hid_output_bl_launch_app(struct cyttsp5 *ts)
 {
 	int rc;
@@ -669,6 +719,10 @@ static irqreturn_t cyttsp5_handle_irq(int irq, void *handle)
 	case HID_BTN_REPORT_ID:
 		cyttsp5_btn_attention(ts->dev);
 		break;
+	case HID_RESPONSE_REPORT_ID:
+		memcpy(ts->response_buf, ts->input_buf, size);
+		complete(&ts->cmd_done);
+		break;
 	default:
 		/* It is not an input but a command response */
 		memcpy(ts->response_buf, ts->input_buf, size);
@@ -880,10 +934,33 @@ static const struct i2c_device_id cyttsp5_i2c_id[] = {
 };
 MODULE_DEVICE_TABLE(i2c, cyttsp5_i2c_id);
 
+static int __maybe_unused cyttsp5_suspend(struct device *dev)
+{
+	struct cyttsp5 *ts = dev_get_drvdata(dev);
+
+	if (!device_may_wakeup(dev))
+		cyttsp5_power_control(ts, false);
+
+	return 0;
+}
+
+static int __maybe_unused cyttsp5_resume(struct device *dev)
+{
+	struct cyttsp5 *ts = dev_get_drvdata(dev);
+
+	if (!device_may_wakeup(dev))
+		cyttsp5_power_control(ts, true);
+
+	return 0;
+}
+
+static SIMPLE_DEV_PM_OPS(cyttsp5_pm, cyttsp5_suspend, cyttsp5_resume);
+
 static struct i2c_driver cyttsp5_i2c_driver = {
 	.driver = {
 		.name = CYTTSP5_NAME,
 		.of_match_table = cyttsp5_of_match,
+		.pm = &cyttsp5_pm,
 	},
 	.probe_new = cyttsp5_i2c_probe,
 	.id_table = cyttsp5_i2c_id,