On Wed, Aug 28, 2019 at 03:03:02AM +0000, Peng Fan wrote:

From: Peng Fan <peng.fan@nxp.com>

This mailbox driver implements a mailbox which signals transmitted data
via an ARM smc (secure monitor call) instruction. The mailbox receiver
is implemented in firmware and can synchronously return data when it
returns execution to the non-secure world again.
An asynchronous receive path is not implemented.
This allows the usage of a mailbox to trigger firmware actions on SoCs
which either don't have a separate management processor or on which such
a core is not available. A user of this mailbox could be the SCP
interface.

Modified from Andre Przywara's v2 patch
https://lore.kernel.org/patchwork/patch/812999/

Cc: Andre Przywara <andre.przywara@arm.com>
Signed-off-by: Peng Fan <peng.fan@nxp.com>
---
 drivers/mailbox/Kconfig           |   7 ++
 drivers/mailbox/Makefile          |   2 +
 drivers/mailbox/arm-smc-mailbox.c | 215 ++++++++++++++++++++++++++++++++++++++
 3 files changed, 224 insertions(+)
 create mode 100644 drivers/mailbox/arm-smc-mailbox.c

[...]

+static int arm_smc_mbox_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct mbox_controller *mbox;
+	struct arm_smc_chan_data *chan_data;
+	const char *method;
+	bool mem_trans = false;
+	int ret, i;
+	u32 val;
+
+	if (!of_property_read_u32(dev->of_node, "arm,num-chans", &val)) {
+		if (!val) {
+			dev_err(dev, "invalid arm,num-chans value %u\n", val);
+			return -EINVAL;
+		}
+	} else {
+		return -EINVAL;
+	}
+
+	if (!of_property_read_string(dev->of_node, "transports", &method)) {
+		if (!strcmp("mem", method)) {
+			mem_trans = true;
+		} else if (!strcmp("reg", method)) {
+			mem_trans = false;
+		} else {
+			dev_warn(dev, "invalid \"transports\" property: %s\n",
+				 method);
+
+			return -EINVAL;
+		}
+	} else {
+		return -EINVAL;
+	}
+
+	if (!of_property_read_string(dev->of_node, "method", &method)) {
+		if (!strcmp("hvc", method)) {
+			invoke_smc_mbox_fn = __invoke_fn_hvc;
+		} else if (!strcmp("smc", method)) {
+			invoke_smc_mbox_fn = __invoke_fn_smc;
+		} else {
+			dev_warn(dev, "invalid \"method\" property: %s\n",
+				 method);
+
+			return -EINVAL;
+		}
+	} else {
+		return -EINVAL;
+	}
+
+	mbox = devm_kzalloc(dev, sizeof(*mbox), GFP_KERNEL);
+	if (!mbox)
+		return -ENOMEM;
+
+	mbox->num_chans = val;
+	mbox->chans = devm_kcalloc(dev, mbox->num_chans, sizeof(*mbox->chans),
+				   GFP_KERNEL);
+	if (!mbox->chans)
+		return -ENOMEM;
+
+	chan_data = devm_kcalloc(dev, mbox->num_chans, sizeof(*chan_data),
+				 GFP_KERNEL);
+	if (!chan_data)
+		return -ENOMEM;
+
+	for (i = 0; i < mbox->num_chans; i++) {
+		u32 function_id;
+
+		ret = of_property_read_u32_index(dev->of_node,
+						 "arm,func-ids", i,
+						 &function_id);

I missed it in binding but I thought we agreed to make this "arm,func-ids"
a required property and not optional ?

--
Regards,
Sudeep