HSI: Add common DT binding for HSI client devices

Implement and document generic DT bindings for HSI clients.

Signed-off-by: Sebastian Reichel <[e-mail]>
Reviewed-by: Pavel Machek <[e-mail]>
Tested-By: Ivaylo Dimitrov <[e-mail]>

Documentation/devicetree/bindings/hsi/client-devices.txt

···
+Each HSI port is supposed to have one child node, which
+symbols the remote device connected to the HSI port. The
+following properties are standardized for HSI clients:
+
+Required HSI configuration properties:
+
+- hsi-channel-ids:	A list of channel ids
+
+- hsi-rx-mode:		Receiver Bit transmission mode ("stream" or "frame")
+- hsi-tx-mode:		Transmitter Bit transmission mode ("stream" or "frame")
+- hsi-mode:		May be used instead hsi-rx-mode and hsi-tx-mode if
+			the transmission mode is the same for receiver and
+			transmitter
+- hsi-speed-kbps:	Max bit transmission speed in kbit/s
+- hsi-flow:		RX flow type ("synchronized" or "pipeline")
+- hsi-arb-mode:		Arbitration mode for TX frame ("round-robin", "priority")
+
+Optional HSI configuration properties:
+
+- hsi-channel-names:	A list with one name per channel specified in the
+			hsi-channel-ids property
+
+
+Device Tree node example for an HSI client:
+
+hsi-controller {
+	hsi-port {
+		modem: hsi-client {
+			compatible = "nokia,n900-modem";
+
+			hsi-channel-ids = <0>, <1>, <2>, <3>;
+			hsi-channel-names = "mcsaab-control",
+					    "speech-control",
+					    "speech-data",
+					    "mcsaab-data";
+			hsi-speed-kbps = <55000>;
+			hsi-mode = "frame";
+			hsi-flow = "synchronized";
+			hsi-arb-mode = "round-robin";
+
+			/* more client specific properties */
+		};
+	};
+};

drivers/hsi/hsi.c

···
 #include <linux/slab.h>
 #include <linux/string.h>
 #include <linux/notifier.h>
+#include <linux/of.h>
+#include <linux/of_device.h>
 #include "hsi_core.h"
 
 static ssize_t modalias_show(struct device *dev,
···
 
 static int hsi_bus_match(struct device *dev, struct device_driver *driver)
 {
-	return strcmp(dev_name(dev), driver->name) == 0;
+	if (of_driver_match_device(dev, driver))
+		return true;
+
+	if (strcmp(dev_name(dev), driver->name) == 0)
+		return true;
+
+	return false;
 }
 
 static struct bus_type hsi_bus_type = {
···
 			hsi_new_client(p, &cl_info->info);
 		}
 }
+
+#ifdef CONFIG_OF
+static struct hsi_board_info hsi_char_dev_info = {
+	.name = "hsi_char",
+};
+
+static int hsi_of_property_parse_mode(struct device_node *client, char *name,
+				      unsigned int *result)
+{
+	const char *mode;
+	int err;
+
+	err = of_property_read_string(client, name, &mode);
+	if (err < 0)
+		return err;
+
+	if (strcmp(mode, "stream") == 0)
+		*result = HSI_MODE_STREAM;
+	else if (strcmp(mode, "frame") == 0)
+		*result = HSI_MODE_FRAME;
+	else
+		return -EINVAL;
+
+	return 0;
+}
+
+static int hsi_of_property_parse_flow(struct device_node *client, char *name,
+				      unsigned int *result)
+{
+	const char *flow;
+	int err;
+
+	err = of_property_read_string(client, name, &flow);
+	if (err < 0)
+		return err;
+
+	if (strcmp(flow, "synchronized") == 0)
+		*result = HSI_FLOW_SYNC;
+	else if (strcmp(flow, "pipeline") == 0)
+		*result = HSI_FLOW_PIPE;
+	else
+		return -EINVAL;
+
+	return 0;
+}
+
+static int hsi_of_property_parse_arb_mode(struct device_node *client,
+					  char *name, unsigned int *result)
+{
+	const char *arb_mode;
+	int err;
+
+	err = of_property_read_string(client, name, &arb_mode);
+	if (err < 0)
+		return err;
+
+	if (strcmp(arb_mode, "round-robin") == 0)
+		*result = HSI_ARB_RR;
+	else if (strcmp(arb_mode, "priority") == 0)
+		*result = HSI_ARB_PRIO;
+	else
+		return -EINVAL;
+
+	return 0;
+}
+
+static void hsi_add_client_from_dt(struct hsi_port *port,
+						struct device_node *client)
+{
+	struct hsi_client *cl;
+	struct hsi_channel channel;
+	struct property *prop;
+	char name[32];
+	int length, cells, err, i, max_chan, mode;
+
+	cl = kzalloc(sizeof(*cl), GFP_KERNEL);
+	if (!cl)
+		return;
+
+	err = of_modalias_node(client, name, sizeof(name));
+	if (err)
+		goto err;
+
+	dev_set_name(&cl->device, "%s", name);
+
+	err = hsi_of_property_parse_mode(client, "hsi-mode", &mode);
+	if (err) {
+		err = hsi_of_property_parse_mode(client, "hsi-rx-mode",
+						 &cl->rx_cfg.mode);
+		if (err)
+			goto err;
+
+		err = hsi_of_property_parse_mode(client, "hsi-tx-mode",
+						 &cl->tx_cfg.mode);
+		if (err)
+			goto err;
+	} else {
+		cl->rx_cfg.mode = mode;
+		cl->tx_cfg.mode = mode;
+	}
+
+	err = of_property_read_u32(client, "hsi-speed-kbps",
+				   &cl->tx_cfg.speed);
+	if (err)
+		goto err;
+	cl->rx_cfg.speed = cl->tx_cfg.speed;
+
+	err = hsi_of_property_parse_flow(client, "hsi-flow",
+					 &cl->rx_cfg.flow);
+	if (err)
+		goto err;
+
+	err = hsi_of_property_parse_arb_mode(client, "hsi-arb-mode",
+					     &cl->rx_cfg.arb_mode);
+	if (err)
+		goto err;
+
+	prop = of_find_property(client, "hsi-channel-ids", &length);
+	if (!prop) {
+		err = -EINVAL;
+		goto err;
+	}
+
+	cells = length / sizeof(u32);
+
+	cl->rx_cfg.num_channels = cells;
+	cl->tx_cfg.num_channels = cells;
+
+	cl->rx_cfg.channels = kzalloc(cells * sizeof(channel), GFP_KERNEL);
+	if (!cl->rx_cfg.channels) {
+		err = -ENOMEM;
+		goto err;
+	}
+
+	cl->tx_cfg.channels = kzalloc(cells * sizeof(channel), GFP_KERNEL);
+	if (!cl->tx_cfg.channels) {
+		err = -ENOMEM;
+		goto err2;
+	}
+
+	max_chan = 0;
+	for (i = 0; i < cells; i++) {
+		err = of_property_read_u32_index(client, "hsi-channel-ids", i,
+						 &channel.id);
+		if (err)
+			goto err3;
+
+		err = of_property_read_string_index(client, "hsi-channel-names",
+						    i, &channel.name);
+		if (err)
+			channel.name = NULL;
+
+		if (channel.id > max_chan)
+			max_chan = channel.id;
+
+		cl->rx_cfg.channels[i] = channel;
+		cl->tx_cfg.channels[i] = channel;
+	}
+
+	cl->rx_cfg.num_hw_channels = max_chan + 1;
+	cl->tx_cfg.num_hw_channels = max_chan + 1;
+
+	cl->device.bus = &hsi_bus_type;
+	cl->device.parent = &port->device;
+	cl->device.release = hsi_client_release;
+	cl->device.of_node = client;
+
+	if (device_register(&cl->device) < 0) {
+		pr_err("hsi: failed to register client: %s\n", name);
+		put_device(&cl->device);
+		goto err3;
+	}
+
+	return;
+
+err3:
+	kfree(cl->tx_cfg.channels);
+err2:
+	kfree(cl->rx_cfg.channels);
+err:
+	kfree(cl);
+	pr_err("hsi client: missing or incorrect of property: err=%d\n", err);
+}
+
+void hsi_add_clients_from_dt(struct hsi_port *port, struct device_node *clients)
+{
+	struct device_node *child;
+
+	/* register hsi-char device */
+	hsi_new_client(port, &hsi_char_dev_info);
+
+	for_each_available_child_of_node(clients, child)
+		hsi_add_client_from_dt(port, child);
+}
+EXPORT_SYMBOL_GPL(hsi_add_clients_from_dt);
+#endif
 
 int hsi_remove_client(struct device *dev, void *data __maybe_unused)
 {
···
 EXPORT_SYMBOL_GPL(hsi_unregister_port_event);
 
 /**
- * hsi_event -Notifies clients about port events
+ * hsi_event - Notifies clients about port events
  * @port: Port where the event occurred
  * @event: The event type
  *

include/linux/hsi/hsi.h

···
 int hsi_remove_client(struct device *dev, void *data);
 void hsi_port_unregister_clients(struct hsi_port *port);
 
+#ifdef CONFIG_OF
+void hsi_add_clients_from_dt(struct hsi_port *port,
+			     struct device_node *clients);
+#else
+static inline void hsi_add_clients_from_dt(struct hsi_port *port,
+					   struct device_node *clients)
+{
+	return;
+}
+#endif
+
 static inline void hsi_controller_set_drvdata(struct hsi_controller *hsi,
 								void *data)
 {