soc: fsl: cpm1: qmc: Add support for child devices

QMC child devices support is needed to avoid orphan DT nodes that use a
simple DT phandle to reference a QMC channel.

Allow to instantiate child devices and also extend the API to get the
qmc_chan using a child device.
Signed-off-by: Herve Codina <herve.codina@bootlin.com>
Link: https://lore.kernel.org/r/20231205152116.122512-7-herve.codina@bootlin.com

drivers/soc/fsl/qe/qmc.c

@@ -1425,8 +1425,16 @@ static int qmc_probe(struct platform_device *pdev)
 
 	platform_set_drvdata(pdev, qmc);
 
+	/* Populate channel related devices */
+	ret = devm_of_platform_populate(qmc->dev);
+	if (ret)
+		goto err_disable_txrx;
+
 	return 0;
 
+err_disable_txrx:
+	qmc_setbits32(qmc->scc_regs + SCC_GSMRL, 0);
+
 err_disable_intr:
 	qmc_write16(qmc->scc_regs + SCC_SCCM, 0);
 
@@ -1465,26 +1473,16 @@ static struct platform_driver qmc_driver = {
 };
 module_platform_driver(qmc_driver);
 
-struct qmc_chan *qmc_chan_get_byphandle(struct device_node *np, const char *phandle_name)
+static struct qmc_chan *qmc_chan_get_from_qmc(struct device_node *qmc_np, unsigned int chan_index)
 {
-	struct of_phandle_args out_args;
 	struct platform_device *pdev;
 	struct qmc_chan *qmc_chan;
 	struct qmc *qmc;
-	int ret;
 
-	ret = of_parse_phandle_with_fixed_args(np, phandle_name, 1, 0,
-					       &out_args);
-	if (ret < 0)
-		return ERR_PTR(ret);
-
-	if (!of_match_node(qmc_driver.driver.of_match_table, out_args.np)) {
-		of_node_put(out_args.np);
+	if (!of_match_node(qmc_driver.driver.of_match_table, qmc_np))
 		return ERR_PTR(-EINVAL);
-	}
 
-	pdev = of_find_device_by_node(out_args.np);
-	of_node_put(out_args.np);
+	pdev = of_find_device_by_node(qmc_np);
 	if (!pdev)
 		return ERR_PTR(-ENODEV);
 
@@ -1494,17 +1492,12 @@ struct qmc_chan *qmc_chan_get_byphandle(struct device_node *np, const char *phan
 		return ERR_PTR(-EPROBE_DEFER);
 	}
 
-	if (out_args.args_count != 1) {
+	if (chan_index >= ARRAY_SIZE(qmc->chans)) {
 		platform_device_put(pdev);
 		return ERR_PTR(-EINVAL);
 	}
 
-	if (out_args.args[0] >= ARRAY_SIZE(qmc->chans)) {
-		platform_device_put(pdev);
-		return ERR_PTR(-EINVAL);
-	}
-
-	qmc_chan = qmc->chans[out_args.args[0]];
+	qmc_chan = qmc->chans[chan_index];
 	if (!qmc_chan) {
 		platform_device_put(pdev);
 		return ERR_PTR(-ENOENT);
@@ -1512,8 +1505,44 @@ struct qmc_chan *qmc_chan_get_byphandle(struct device_node *np, const char *phan
 
 	return qmc_chan;
 }
+
+struct qmc_chan *qmc_chan_get_byphandle(struct device_node *np, const char *phandle_name)
+{
+	struct of_phandle_args out_args;
+	struct qmc_chan *qmc_chan;
+	int ret;
+
+	ret = of_parse_phandle_with_fixed_args(np, phandle_name, 1, 0,
+					       &out_args);
+	if (ret < 0)
+		return ERR_PTR(ret);
+
+	if (out_args.args_count != 1) {
+		of_node_put(out_args.np);
+		return ERR_PTR(-EINVAL);
+	}
+
+	qmc_chan = qmc_chan_get_from_qmc(out_args.np, out_args.args[0]);
+	of_node_put(out_args.np);
+	return qmc_chan;
+}
 EXPORT_SYMBOL(qmc_chan_get_byphandle);
 
+struct qmc_chan *qmc_chan_get_bychild(struct device_node *np)
+{
+	struct device_node *qmc_np;
+	u32 chan_index;
+	int ret;
+
+	qmc_np = np->parent;
+	ret = of_property_read_u32(np, "reg", &chan_index);
+	if (ret)
+		return ERR_PTR(-EINVAL);
+
+	return qmc_chan_get_from_qmc(qmc_np, chan_index);
+}
+EXPORT_SYMBOL(qmc_chan_get_bychild);
+
 void qmc_chan_put(struct qmc_chan *chan)
 {
 	put_device(chan->qmc->dev);
@@ -1550,6 +1579,28 @@ struct qmc_chan *devm_qmc_chan_get_byphandle(struct device *dev,
 }
 EXPORT_SYMBOL(devm_qmc_chan_get_byphandle);
 
+struct qmc_chan *devm_qmc_chan_get_bychild(struct device *dev,
+					   struct device_node *np)
+{
+	struct qmc_chan *qmc_chan;
+	struct qmc_chan **dr;
+
+	dr = devres_alloc(devm_qmc_chan_release, sizeof(*dr), GFP_KERNEL);
+	if (!dr)
+		return ERR_PTR(-ENOMEM);
+
+	qmc_chan = qmc_chan_get_bychild(np);
+	if (!IS_ERR(qmc_chan)) {
+		*dr = qmc_chan;
+		devres_add(dev, dr);
+	} else {
+		devres_free(dr);
+	}
+
+	return qmc_chan;
+}
+EXPORT_SYMBOL(devm_qmc_chan_get_bychild);
+
 MODULE_AUTHOR("Herve Codina <herve.codina@bootlin.com>");
 MODULE_DESCRIPTION("CPM QMC driver");
 MODULE_LICENSE("GPL");

include/soc/fsl/qe/qmc.h

@@ -17,9 +17,11 @@ struct device;
 struct qmc_chan;
 
 struct qmc_chan *qmc_chan_get_byphandle(struct device_node *np, const char *phandle_name);
+struct qmc_chan *qmc_chan_get_bychild(struct device_node *np);
 void qmc_chan_put(struct qmc_chan *chan);
 struct qmc_chan *devm_qmc_chan_get_byphandle(struct device *dev, struct device_node *np,
 					     const char *phandle_name);
+struct qmc_chan *devm_qmc_chan_get_bychild(struct device *dev, struct device_node *np);
 
 enum qmc_mode {
 	QMC_TRANSPARENT,