Date: Thu, 23 May 2024 10:02:21 +0200
From: Markus Schneider-Pargmann <msp@...libre.com>
To: Nishanth Menon <nm@...com>,
	Tero Kristo <kristo@...nel.org>,
	Santosh Shilimkar <ssantosh@...nel.org>,
	Rob Herring <robh@...nel.org>,
	Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
	Conor Dooley <conor+dt@...nel.org>,
	Vignesh Raghavendra <vigneshr@...com>
Cc: Vibhore Vardhan <vibhore@...com>,
	Kevin Hilman <khilman@...libre.com>,
	Dhruva Gole <d-gole@...com>,
	linux-arm-kernel@...ts.infradead.org,
	devicetree@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	Markus Schneider-Pargmann <msp@...libre.com>
Subject: [PATCH 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.

Signed-off-by: Markus Schneider-Pargmann <msp@...libre.com>
---
 drivers/firmware/ti_sci.c | 135 +++++++++++++++++++++++++++++++++++++-
 drivers/firmware/ti_sci.h |  31 +++++++++
 2 files changed, 165 insertions(+), 1 deletion(-)

diff --git a/drivers/firmware/ti_sci.c b/drivers/firmware/ti_sci.c
index 160968301b1f..04730c4df2de 100644
--- a/drivers/firmware/ti_sci.c
+++ b/drivers/firmware/ti_sci.c
@@ -116,6 +116,9 @@ 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)
@@ -380,6 +383,28 @@ static void ti_sci_put_one_xfer(struct ti_sci_xfers_info *minfo,
 	up(&minfo->sem_xfer_count);
 }
 
+/**
+ * ti_sci_do_send() - Do one send, do not expect a response
+ * @info:	Pointer to SCI entity information
+ * @xfer:	Transfer to initiate
+ *
+ * Return: If send error, return corresponding error, else
+ *	   if all goes well, return 0.
+ */
+static inline int ti_sci_do_send(struct ti_sci_info *info,
+				 struct ti_sci_xfer *xfer)
+{
+	int ret;
+
+	ret = mbox_send_message(info->chan_tx, &xfer->tx_message);
+	if (ret < 0)
+		return ret;
+
+	mbox_client_txdone(info->chan_tx, ret);
+
+	return 0;
+}
+
 /**
  * ti_sci_do_xfer() - Do one transfer
  * @info:	Pointer to SCI entity information
@@ -3262,6 +3287,79 @@ static int tisci_reboot_handler(struct sys_off_data *data)
 	return NOTIFY_BAD;
 }
 
+/* Does not return if successful */
+static int tisci_enter_partial_io(struct ti_sci_info *info)
+{
+	struct ti_sci_msg_req_prepare_sleep *req;
+	struct ti_sci_xfer *xfer;
+	struct device *dev = info->dev;
+	int ret = 0;
+
+	xfer = ti_sci_get_one_xfer(info, TI_SCI_MSG_PREPARE_SLEEP,
+				   TI_SCI_FLAG_REQ_GENERIC_NORESPONSE,
+				   sizeof(*req), sizeof(struct ti_sci_msg_hdr));
+	if (IS_ERR(xfer)) {
+		ret = PTR_ERR(xfer);
+		dev_err(dev, "Message alloc failed(%d)\n", ret);
+		return ret;
+	}
+
+	req = (struct ti_sci_msg_req_prepare_sleep *)xfer->xfer_buf;
+	req->mode = TISCI_MSG_VALUE_SLEEP_MODE_PARTIAL_IO;
+	req->ctx_lo = 0;
+	req->ctx_hi = 0;
+	req->debug_flags = 0;
+
+	ret = ti_sci_do_send(info, xfer);
+	if (ret) {
+		dev_err(dev, "Mbox send fail %d\n", ret);
+		goto fail;
+	}
+
+fail:
+	ti_sci_put_one_xfer(&info->minfo, xfer);
+
+	return ret;
+}
+
+static int tisci_sys_off_handler(struct sys_off_data *data)
+{
+	struct ti_sci_info *info = data->cb_data;
+	int i;
+	int ret;
+	bool enter_partial_io = false;
+
+	for (i = 0; i != info->nr_wakeup_sources; ++i) {
+		struct platform_device *pdev =
+			of_find_device_by_node(info->wakeup_source_nodes[i]);
+
+		if (!pdev)
+			continue;
+
+		if (device_may_wakeup(&pdev->dev)) {
+			dev_dbg(info->dev, "%pOFp identified as wakeup source\n",
+				info->wakeup_source_nodes[i]);
+			enter_partial_io = true;
+		}
+	}
+
+	if (!enter_partial_io)
+		return NOTIFY_DONE;
+
+	ret = tisci_enter_partial_io(info);
+
+	if (ret)
+		dev_err(info->dev,
+			"Failed to enter Partial-IO %pe, halting system\n",
+			ERR_PTR(ret));
+
+	/* Halt system/code execution */
+	while (1)
+		;
+
+	return NOTIFY_DONE;
+}
+
 /* Description for K2G */
 static const struct ti_sci_desc ti_sci_pmmc_k2g_desc = {
 	.default_host_id = 2,
@@ -3398,6 +3496,35 @@ static int ti_sci_probe(struct platform_device *pdev)
 		goto out;
 	}
 
+	if (of_property_read_bool(dev->of_node, "ti,partial-io-wakeup-sources")) {
+		info->nr_wakeup_sources =
+			of_count_phandle_with_args(dev->of_node,
+						   "ti,partial-io-wakeup-sources",
+						   NULL);
+		info->wakeup_source_nodes =
+			devm_kzalloc(dev, sizeof(*info->wakeup_source_nodes),
+				     GFP_KERNEL);
+
+		for (i = 0; i != info->nr_wakeup_sources; ++i) {
+			struct device_node *devnode =
+				of_parse_phandle(dev->of_node,
+						 "ti,partial-io-wakeup-sources",
+						 i);
+			info->wakeup_source_nodes[i] = devnode;
+		}
+
+		ret = devm_register_sys_off_handler(dev,
+						    SYS_OFF_MODE_POWER_OFF,
+						    SYS_OFF_PRIO_FIRMWARE,
+						    tisci_sys_off_handler,
+						    info);
+		if (ret) {
+			dev_err(dev, "Failed to register sys_off_handler %pe\n",
+				ERR_PTR(ret));
+			goto out;
+		}
+	}
+
 	dev_info(dev, "ABI: %d.%d (firmware rev 0x%04x '%s')\n",
 		 info->handle.version.abi_major, info->handle.version.abi_minor,
 		 info->handle.version.firmware_revision,
@@ -3407,7 +3534,13 @@ static int ti_sci_probe(struct platform_device *pdev)
 	list_add_tail(&info->node, &ti_sci_list);
 	mutex_unlock(&ti_sci_list_mutex);
 
-	return of_platform_populate(dev->of_node, NULL, NULL, dev);
+	ret = of_platform_populate(dev->of_node, NULL, NULL, dev);
+	if (ret) {
+		dev_err(dev, "platform_populate failed %pe\n", ERR_PTR(ret));
+		goto out;
+	}
+	return 0;
+
 out:
 	if (!IS_ERR(info->chan_tx))
 		mbox_free_channel(info->chan_tx);
diff --git a/drivers/firmware/ti_sci.h b/drivers/firmware/ti_sci.h
index ef3a8214d002..6d8b12341f68 100644
--- a/drivers/firmware/ti_sci.h
+++ b/drivers/firmware/ti_sci.h
@@ -35,6 +35,9 @@
 #define TI_SCI_MSG_QUERY_CLOCK_FREQ	0x010d
 #define TI_SCI_MSG_GET_CLOCK_FREQ	0x010e
 
+/* Low Power Mode Requests */
+#define TI_SCI_MSG_PREPARE_SLEEP	0x0300
+
 /* Resource Management Requests */
 #define TI_SCI_MSG_GET_RESOURCE_RANGE	0x1500
 
@@ -545,6 +548,34 @@ struct ti_sci_msg_resp_get_clock_freq {
 	u64 freq_hz;
 } __packed;
 
+#define TISCI_MSG_VALUE_SLEEP_MODE_DEEP_SLEEP				0x0
+#define TISCI_MSG_VALUE_SLEEP_MODE_MCU_ONLY				0x1
+#define TISCI_MSG_VALUE_SLEEP_MODE_STANDBY				0x2
+#define TISCI_MSG_VALUE_SLEEP_MODE_PARTIAL_IO				0x3
+
+/**
+ * struct tisci_msg_prepare_sleep_req - Request for TISCI_MSG_PREPARE_SLEEP.
+ *
+ * @hdr				TISCI header to provide ACK/NAK flags to the host.
+ * @mode			Low power mode to enter.
+ * @ctx_lo			Low 32-bits of physical pointer to address to use for context save.
+ * @ctx_hi			High 32-bits of physical pointer to address to use for context save.
+ * @debug_flags			Flags that can be set to halt the sequence during suspend or
+ *				resume to allow JTAG connection and debug.
+ *
+ * This message is used as the first step of entering a low power mode. It
+ * allows configurable information, including which state to enter to be
+ * easily shared from the application, as this is a non-secure message and
+ * therefore can be sent by anyone.
+ */
+struct ti_sci_msg_req_prepare_sleep {
+	struct ti_sci_msg_hdr	hdr;
+	u8			mode;
+	u32			ctx_lo;
+	u32			ctx_hi;
+	u32			debug_flags;
+} __packed;
+
 #define TI_SCI_IRQ_SECONDARY_HOST_INVALID	0xff
 
 /**
-- 
2.43.0

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