greybus: arche-platform: Convert delayed work to do only hub3613 configuration

This is preparation of interrupt handling support, where APB coldboot
and wake/detect handling will be handled as response to wake/detect
interrupt.
Due to slower I2C write operations in HUB configuration, it is important
to separate HUB configuration, and probably delay it after APB is
cold booted.

Note that delayed work will be scheduled from interrupt handler,
in following patches.

To satisfy build (and bisect), remove apb_cold_boot() fn, which will be
added back in the patch where it gets used again.

Testing Done: Tested on DB3.5 platform.
Signed-off-by: Vaibhav Hiremath <vaibhav.hiremath@linaro.org>
Reviewed-by: Michael Scott <michael.scott@linaro.org>
Tested-by: Michael Scott <michael.scott@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>

drivers/staging/greybus/arche-platform.c

@@ -47,18 +47,6 @@ static inline void svc_reset_onoff(unsigned int gpio, bool onoff)
 	gpio_set_value(gpio, onoff);
 }
 
-static int apb_cold_boot(struct device *dev, void *data)
-{
-	int ret;
-
-	ret = apb_ctrl_coldboot(dev);
-	if (ret)
-		dev_warn(dev, "failed to coldboot\n");
-
-	/*Child nodes are independent, so do not exit coldboot operation */
-	return 0;
-}
-
 static int apb_fw_flashing_state(struct device *dev, void *data)
 {
 	int ret;
@@ -79,50 +67,17 @@ static int apb_poweroff(struct device *dev, void *data)
 }
 
 /**
- * svc_delayed_work - Time to give SVC to boot.
+ * hub_conf_delayed_work - Configures USB3613 device to HUB mode
+ *
+ * The idea here is to split the APB coldboot operation with slow HUB configuration,
+ * so that driver response to wake/detect event can be met.
+ * So expectation is, once code reaches here, means initial unipro linkup
+ * between APB<->Switch was successful, so now just take it to AP.
  */
-static void svc_delayed_work(struct work_struct *work)
+static void hub_conf_delayed_work(struct work_struct *work)
 {
 	struct arche_platform_drvdata *arche_pdata =
 		container_of(work, struct arche_platform_drvdata, delayed_work.work);
-	int timeout = 50;
-
-	/*
-	 * 1.   SVC and AP boot independently, with AP<-->SVC wake/detect pin
-	 *      deasserted (LOW in this case)
-	 * 2.1. SVC allows 360 milliseconds to elapse after switch boots to work
-	 *      around bug described in ENG-330.
-	 * 2.2. AP asserts wake/detect pin (HIGH) (this can proceed in parallel with 2.1)
-	 * 3.   SVC detects assertion of wake/detect pin, and sends "wake out" signal to AP
-	 * 4.   AP receives "wake out" signal, takes AP Bridges through their power
-	 *      on reset sequence as defined in the bridge ASIC reference manuals
-	 * 5. AP takes USB3613 through its power on reset sequence
-	 * 6. AP enumerates AP Bridges
-	 */
-	gpio_set_value(arche_pdata->wake_detect_gpio, 1);
-	gpio_direction_input(arche_pdata->wake_detect_gpio);
-	do {
-		/* Read the wake_detect GPIO, for WAKE_OUT event from SVC */
-		if (gpio_get_value(arche_pdata->wake_detect_gpio) == 0)
-			break;
-
-		msleep(100);
-	} while(timeout--);
-
-	if (timeout < 0) {
-		/* FIXME: We may want to limit retries here */
-		dev_warn(arche_pdata->dev,
-			"Timed out on wake/detect, rescheduling handshake\n");
-		gpio_direction_output(arche_pdata->wake_detect_gpio, 0);
-		schedule_delayed_work(&arche_pdata->delayed_work, msecs_to_jiffies(2000));
-		return;
-	}
-
-	/* Bring APB out of reset: cold boot sequence */
-	device_for_each_child(arche_pdata->dev, NULL, apb_cold_boot);
-
-	/* re-assert wake_detect to confirm SVC WAKE_OUT */
-	gpio_direction_output(arche_pdata->wake_detect_gpio, 1);
 
 	/* Enable HUB3613 into HUB mode. */
 	if (usb3613_hub_mode_ctrl(true))
@@ -226,8 +181,6 @@ static ssize_t state_store(struct device *dev,
 			return count;
 
 		ret = arche_platform_coldboot_seq(arche_pdata);
-		/* Give enough time for SVC to boot and then handshake with SVC */
-		schedule_delayed_work(&arche_pdata->delayed_work, msecs_to_jiffies(2000));
 	} else if (sysfs_streq(buf, "standby")) {
 		if (arche_pdata->state == ARCHE_PLATFORM_STATE_STANDBY)
 			return count;
@@ -396,8 +349,7 @@ static int arche_platform_probe(struct platform_device *pdev)
 		goto err_populate;
 	}
 
-	INIT_DELAYED_WORK(&arche_pdata->delayed_work, svc_delayed_work);
-	schedule_delayed_work(&arche_pdata->delayed_work, msecs_to_jiffies(2000));
+	INIT_DELAYED_WORK(&arche_pdata->delayed_work, hub_conf_delayed_work);
 
 	dev_info(dev, "Device registered successfully\n");
 	return 0;