mailbox: zynqmp: support mulitple mboxes via device-tree

As of now only one mailbox agent is supported by mailbox driver.
On zynqmp platform there are about 7 mailbox agents which can communicate
over same IPI channel to U-Boot. This patch series introduces new
"zynqmp_ipi_dest" driver which adds one to multi-channel mailbox
support.

Following format in device-tree is expected as per latest bindings:
zynqmp-ipi {
	compatible = "xlnx,zynqmp-ipi-mailbox";

	mbox_1: mailbox@1 {
		/* New compatible for child node */
		compatible = "xlnx,zynqmp-ipi-dest-mailbox";
		...
	};

	...

	mbox_n: mailbox@n {
		compatible = "xlnx,zynqmp-ipi-dest-mailbox";
		...
	}
};

Then mailbox client uses child mailbox node as following:

ipi-dest-1 {
	...
	mboxes = <mbox_1 0>, <mbox_1 1>;
	mbox-names = "tx", "rx";
	...
};

New "zynqmp_ipi_dest" driver is for devices with
"xlnx,zynqmp-ipi-dest-mailbox" compatible string. This driver will take care
of mailbox send recv ops and it replaces previous "zynqmp_ipi" driver.
Now "zynqmp_ipi" driver simply binds each child device with "zynqmp_ipi_dest"
driver.

However, its important to maintain backward comaptibility with previous
bindings where child node does not have compatible string. In such case, new
driver isn't probed by U-Boot during boot and system fails to boot. To
resolve this issue firmware-zynqmp.c driver probes all the IPI parent node
driver which binds each child node device with "zynqmp_ipi_dest" driver.

This makes sure corresponding child driver will be
probed when requested using mbox_get_by_name or mbox_get_by_idx
framework calls.

This way multiple mailbox agents are supported in device-tree without breaking
previous binding support.

Signed-off-by: Tanmay Shah <tanmay.shah@amd.com>
Link: https://lore.kernel.org/r/20231204215620.63334-4-tanmay.shah@amd.com
Signed-off-by: Michal Simek <michal.simek@amd.com>

1 files changed, 22 insertions, 0 deletions

diff --git a/drivers/firmware/firmware-zynqmp.c b/drivers/firmware/firmware-zynqmp.c
index 8ea15c7ed3..dfad798a2e 100644
--- a/drivers/firmware/firmware-zynqmp.c
+++ b/drivers/firmware/firmware-zynqmp.c
@@ -8,6 +8,7 @@
 #include <common.h>
 #include <cpu_func.h>
 #include <dm.h>
+#include <dm/device_compat.h>
 #include <dm/lists.h>
 #include <log.h>
 #include <zynqmp_firmware.h>
@@ -290,10 +291,31 @@ int zynqmp_pmufw_load_config_object(const void *cfg_obj, size_t size)
 
 static int zynqmp_power_probe(struct udevice *dev)
 {
+	struct udevice *ipi_dev;
+	ofnode ipi_node;
 	int ret;
 
 	debug("%s, (dev=%p)\n", __func__, dev);
 
+	/*
+	 * Probe all IPI parent node driver. It is important to have IPI
+	 * devices available when requested by mbox_get_by* API.
+	 * If IPI device isn't available, then mailbox request fails and
+	 * that causes system boot failure.
+	 * To avoid this make sure all IPI parent drivers are probed here,
+	 * and IPI parent driver binds each child node to mailbox driver.
+	 * This way mbox_get_by_* API will have correct mailbox device
+	 * driver probed.
+	 */
+	ofnode_for_each_compatible_node(ipi_node, "xlnx,zynqmp-ipi-mailbox") {
+		ret = uclass_get_device_by_ofnode(UCLASS_NOP, ipi_node, &ipi_dev);
+		if (ret) {
+			dev_err(dev, "failed to get IPI device from node %s\n",
+				ofnode_get_name(ipi_node));
+			return ret;
+		}
+	}
+
 	ret = mbox_get_by_name(dev, "tx", &zynqmp_power.tx_chan);
 	if (ret) {
 		debug("%s: Cannot find tx mailbox\n", __func__);