Re: [PATCH v2 2/6] firmware: ti_sci: Partial-IO support

Add support for Partial-IO poweroff. In Partial-IO pins of a few modules
can generate system wakeups while DDR memory is not powered resulting in
a fresh boot of the system. The modules that can be wakeup sources are
defined by the devicetree.

Only wakeup sources that are actually enabled by the user will be
considered as a an active wakeup source. If none of the wakeup sources
are enabled the system will do a normal poweroff. If at least one wakeup
source is enabled it will instead send a TI_SCI_MSG_PREPARE_SLEEP
message from the sys_off handler. Sending this message will result in an
immediate shutdown of the system. No execution is expected after this
point. The code will enter an infinite loop.

The wakeup source device nodes are gathered during probe. But they are
only resolved to the actual devices in the sys_off handler, if they
exist. If they do not exist, they are ignored.

A short documentation about Partial-IO can be found in section 6.2.4.5
of the TRM at
  https://www.ti.com/lit/pdf/spruiv7

Signed-off-by: Markus Schneider-Pargmann <msp@baylibre.com>
---
 drivers/firmware/ti_sci.c | 160 +++++++++++++++++++++++++++++++++-----
 drivers/firmware/ti_sci.h |  34 ++++++++
 2 files changed, 175 insertions(+), 19 deletions(-)

diff --git a/drivers/firmware/ti_sci.c b/drivers/firmware/ti_sci.c
index 160968301b1f..ba2e56da0215 100644
--- a/drivers/firmware/ti_sci.c
+++ b/drivers/firmware/ti_sci.c

@@ -99,6 +99,9 @@ struct ti_sci_desc {
  * @node:	list head
  * @host_id:	Host ID
  * @users:	Number of users of this instance
+ * @nr_wakeup_sources: Number of device nodes in wakeup_source_nodes
+ * @wakeup_source_nodes: Array of all device_nodes listed as wakeup sources in
+ *			 the devicetree
  */
 struct ti_sci_info {
 	struct device *dev;

@@ -116,6 +119,9 @@ struct ti_sci_info {
 	u8 host_id;
 	/* protected by ti_sci_list_mutex */
 	int users;
+
+	int nr_wakeup_sources;
+	struct device_node **wakeup_source_nodes;
 };
 
 #define cl_to_ti_sci_info(c)	container_of(c, struct ti_sci_info, cl)

@@ -392,10 +398,13 @@ static void ti_sci_put_one_xfer(struct ti_sci_xfers_info *minfo,
 static inline int ti_sci_do_xfer(struct ti_sci_info *info,
 				 struct ti_sci_xfer *xfer)
 {
+	struct ti_sci_msg_hdr *hdr = (struct ti_sci_msg_hdr *)xfer->tx_message.buf;
 	int ret;
 	int timeout;
 	struct device *dev = info->dev;
 	bool done_state = true;
+	bool response_expected = !!(hdr->flags & (TI_SCI_FLAG_REQ_ACK_ON_PROCESSED |
+						  TI_SCI_FLAG_REQ_ACK_ON_RECEIVED));

 
 	ret = mbox_send_message(info->chan_tx, &xfer->tx_message);
 	if (ret < 0)

@@ -403,25 +412,27 @@ static inline int ti_sci_do_xfer(struct ti_sci_info *info,
 
 	ret = 0;
 
-	if (system_state <= SYSTEM_RUNNING) {
-		/* And we wait for the response. */
-		timeout = msecs_to_jiffies(info->desc->max_rx_timeout_ms);
-		if (!wait_for_completion_timeout(&xfer->done, timeout))
-			ret = -ETIMEDOUT;
-	} else {
-		/*
-		 * If we are !running, we cannot use wait_for_completion_timeout
-		 * during noirq phase, so we must manually poll the completion.
-		 */
-		ret = read_poll_timeout_atomic(try_wait_for_completion, done_state,
-					       done_state, 1,
-					       info->desc->max_rx_timeout_ms * 1000,
-					       false, &xfer->done);
-	}
+	if (response_expected) {

 	/*
 	 * NOTE: we might prefer not to need the mailbox ticker to manage the

@@ -3262,6 +3273,82 @@ static int tisci_reboot_handler(struct sys_off_data *data)
 	return NOTIFY_BAD;
 }
 

+
+	return NOTIFY_DONE;
+}
+
 /* Description for K2G */
 static const struct ti_sci_desc ti_sci_pmmc_k2g_desc = {
 	.default_host_id = 2,

@@ -3398,6 +3485,35 @@ static int ti_sci_probe(struct platform_device *pdev)
 		goto out;
 	}
 
+	if (of_property_read_bool(dev->of_node, "ti,partial-io-wakeup-sources")) {