powerpc/vas, nx-842: Define and use chip_to_vas_id()

Define a helper, chip_to_vas_id() to map a given chip id to corresponding
vas id.

Normally, callers of vas_rx_win_open() and vas_tx_win_open() want the VAS
window to be on the same chip where the calling thread is executing. These
callers can pass in -1 for the VAS id.

This interface will be useful if a thread running on one chip wants to open
a window on another chip (like the NX-842 driver does during start up).

Signed-off-by: Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

arch/powerpc/include/asm/vas.h

@@ -103,6 +103,15 @@ struct vas_tx_win_attr {
 	bool rx_win_ord_mode;
 };
 
+/*
+ * Helper to map a chip id to VAS id.
+ * For POWER9, this is a 1:1 mapping. In the future this maybe a 1:N
+ * mapping in which case, we will need to update this helper.
+ *
+ * Return the VAS id or -1 if no matching vasid is found.
+ */
+int chip_to_vas_id(int chipid);
+
 /*
  * Helper to initialize receive window attributes to defaults for an
  * NX window.

arch/powerpc/platforms/powernv/vas.c

@@ -123,6 +123,17 @@ struct vas_instance *find_vas_instance(int vasid)
 	return NULL;
 }
 
+int chip_to_vas_id(int chipid)
+{
+	int cpu;
+
+	for_each_possible_cpu(cpu) {
+		if (cpu_to_chip_id(cpu) == chipid)
+			return per_cpu(cpu_vas_id, cpu);
+	}
+	return -1;
+}
+
 static int vas_probe(struct platform_device *pdev)
 {
 	return init_vas_instance(pdev);

drivers/crypto/nx/nx-842-powernv.c

@@ -847,24 +847,12 @@ static int __init nx842_powernv_probe_vas(struct device_node *pn)
 		return -EINVAL;
 	}
 
-	for_each_compatible_node(dn, NULL, "ibm,power9-vas-x") {
-		if (of_get_ibm_chip_id(dn) == chip_id)
-			break;
-	}
-
-	if (!dn) {
-		pr_err("Missing VAS device node\n");
+	vasid = chip_to_vas_id(chip_id);
+	if (vasid < 0) {
+		pr_err("Unable to map chip_id %d to vasid\n", chip_id);
 		return -EINVAL;
 	}
 
-	if (of_property_read_u32(dn, "ibm,vas-id", &vasid)) {
-		pr_err("Missing ibm,vas-id device property\n");
-		of_node_put(dn);
-		return -EINVAL;
-	}
-
-	of_node_put(dn);
-
 	for_each_child_of_node(pn, dn) {
 		if (of_device_is_compatible(dn, "ibm,p9-nx-842")) {
 			ret = vas_cfg_coproc_info(dn, chip_id, vasid);