From a7c1456eb3e8f99ed908b2ccce9a4045c2d3c85e Mon Sep 17 00:00:00 2001
From: Phil Elwell <phil@raspberrypi.com>
Date: Thu, 14 Mar 2024 09:55:31 +0000
Subject: [PATCH 0965/1085] i2c: mux: Add support for generic base-nr property

i2c_mux_add_adapter takes a force_nr parameter that allows an explicit
bus number to be associated with a channel. However, only i2c-mux-reg
and i2c-mux-gpio make use of it.

To help with situations where it is desirable to have a fixed, known
base address for the channels of a mux, create a "base-nr" property.
When force_nr is 0 and base-nr is set and non-zero, form a force_nr
value from the sum of base-nr and the channel ID.

Signed-off-by: Phil Elwell <phil@raspberrypi.com>
---
 drivers/i2c/i2c-mux.c | 5 +++++
 1 file changed, 5 insertions(+)

--- a/drivers/i2c/i2c-mux.c
+++ b/drivers/i2c/i2c-mux.c
@@ -355,8 +355,13 @@ int i2c_mux_add_adapter(struct i2c_mux_c
 	if (muxc->dev->of_node) {
 		struct device_node *dev_node = muxc->dev->of_node;
 		struct device_node *mux_node, *child = NULL;
+		u32 base_nr = 0;
 		u32 reg;
 
+		of_property_read_u32(dev_node, "base-nr", &base_nr);
+		if (!force_nr)
+			force_nr = base_nr;
+
 		if (muxc->arbitrator)
 			mux_node = of_get_child_by_name(dev_node, "i2c-arb");
 		else if (muxc->gate)
