remoteproc: pru: add support for configuring GPMUX based on client setup

The GPMUX config value for a PRU device can now be configured by client
by specifying it in the device node ti,pruss-gp-mux-sel.

Signed-off-by: Tero Kristo <t-kristo@ti.com>
Signed-off-by: Suman Anna <s-anna@ti.com>
Signed-off-by: MD Danish Anwar <danishanwar@ti.com>
Link: https://lore.kernel.org/r/20230802064925.1895750-1-danishanwar@ti.com
Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>

Author: Tero Kristo

drivers/remoteproc/pru_rproc.c

@@ -110,6 +110,7 @@ struct pru_private_data {
  * @dbg_single_step: debug state variable to set PRU into single step mode
  * @dbg_continuous: debug state variable to restore PRU execution mode
  * @evt_count: number of mapped events
+ * @gpmux_save: saved value for gpmux config
  */
 struct pru_rproc {
 	int id;
@@ -128,6 +129,7 @@ struct pru_rproc {
 	u32 dbg_single_step;
 	u32 dbg_continuous;
 	u8 evt_count;
+	u8 gpmux_save;
 };
 
 static inline u32 pru_control_read_reg(struct pru_rproc *pru, unsigned int reg)
@@ -229,6 +231,7 @@ struct rproc *pru_rproc_get(struct device_node *np, int index,
 	struct device *dev;
 	const char *fw_name;
 	int ret;
+	u32 mux;
 
 	rproc = __pru_rproc_get(np, index);
 	if (IS_ERR(rproc))
@@ -253,6 +256,23 @@ struct rproc *pru_rproc_get(struct device_node *np, int index,
 	if (pru_id)
 		*pru_id = pru->id;
 
+	ret = pruss_cfg_get_gpmux(pru->pruss, pru->id, &pru->gpmux_save);
+	if (ret) {
+		dev_err(dev, "failed to get cfg gpmux: %d\n", ret);
+		goto err;
+	}
+
+	/* An error here is acceptable for backward compatibility */
+	ret = of_property_read_u32_index(np, "ti,pruss-gp-mux-sel", index,
+					 &mux);
+	if (!ret) {
+		ret = pruss_cfg_set_gpmux(pru->pruss, pru->id, mux);
+		if (ret) {
+			dev_err(dev, "failed to set cfg gpmux: %d\n", ret);
+			goto err;
+		}
+	}
+
 	ret = of_property_read_string_index(np, "firmware-name", index,
 					    &fw_name);
 	if (!ret) {
@@ -291,6 +311,8 @@ void pru_rproc_put(struct rproc *rproc)
 
 	pru = rproc->priv;
 
+	pruss_cfg_set_gpmux(pru->pruss, pru->id, pru->gpmux_save);
+
 	pru_rproc_set_firmware(rproc, NULL);
 
 	mutex_lock(&pru->lock);