From 3fd0fe2e8320084968852835836f9abe98c0d66a Mon Sep 17 00:00:00 2001
From: Nuno Sa <nuno.sa@analog.com>
Date: Tue, 11 Mar 2025 08:51:19 +0900
Subject: [PATCH] clk: clk-axi-clkgen: make sure to enable the AXI bus clock

BugLink: https://bugs.launchpad.net/bugs/2101915

[ Upstream commit c64ef7e4851d1a9abbb7f7833e4936973ac5ba79 ]

In order to access the registers of the HW, we need to make sure that
the AXI bus clock is enabled. Hence let's increase the number of clocks
by one.

In order to keep backward compatibility and make sure old DTs still work
we check if clock-names is available or not. If it is, then we can
disambiguate between really having the AXI clock or a parent clock and
so we can enable the bus clock. If not, we fallback to what was done
before and don't explicitly enable the AXI bus clock.

Note that if clock-names is given, the axi clock must be the last one in
the phandle array (also enforced in the DT bindings) so that we can reuse
as much code as possible.

Fixes: 0e646c52cf0e ("clk: Add axi-clkgen driver")
Signed-off-by: Nuno Sa <nuno.sa@analog.com>
Link: https://lore.kernel.org/r/20241029-axi-clkgen-fix-axiclk-v2-2-bc5e0733ad76@analog.com
Signed-off-by: Stephen Boyd <sboyd@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Koichiro Den <koichiro.den@canonical.com>
Signed-off-by: Stefan Bader <stefan.bader@canonical.com>
---
 drivers/clk/clk-axi-clkgen.c | 22 ++++++++++++++++++++--
 1 file changed, 20 insertions(+), 2 deletions(-)

diff --git a/drivers/clk/clk-axi-clkgen.c b/drivers/clk/clk-axi-clkgen.c
index bf4d8ddc93ae..934e53a96ddd 100644
--- a/drivers/clk/clk-axi-clkgen.c
+++ b/drivers/clk/clk-axi-clkgen.c
@@ -7,6 +7,7 @@
  */
 
 #include <linux/platform_device.h>
+#include <linux/clk.h>
 #include <linux/clk-provider.h>
 #include <linux/slab.h>
 #include <linux/io.h>
@@ -512,6 +513,7 @@ static int axi_clkgen_probe(struct platform_device *pdev)
 	struct clk_init_data init;
 	const char *parent_names[2];
 	const char *clk_name;
+	struct clk *axi_clk;
 	unsigned int i;
 	int ret;
 
@@ -528,8 +530,24 @@ static int axi_clkgen_probe(struct platform_device *pdev)
 		return PTR_ERR(axi_clkgen->base);
 
 	init.num_parents = of_clk_get_parent_count(pdev->dev.of_node);
-	if (init.num_parents < 1 || init.num_parents > 2)
-		return -EINVAL;
+
+	axi_clk = devm_clk_get_enabled(&pdev->dev, "s_axi_aclk");
+	if (!IS_ERR(axi_clk)) {
+		if (init.num_parents < 2 || init.num_parents > 3)
+			return -EINVAL;
+
+		init.num_parents -= 1;
+	} else {
+		/*
+		 * Legacy... So that old DTs which do not have clock-names still
+		 * work. In this case we don't explicitly enable the AXI bus
+		 * clock.
+		 */
+		if (PTR_ERR(axi_clk) != -ENOENT)
+			return PTR_ERR(axi_clk);
+		if (init.num_parents < 1 || init.num_parents > 2)
+			return -EINVAL;
+	}
 
 	for (i = 0; i < init.num_parents; i++) {
 		parent_names[i] = of_clk_get_parent_name(pdev->dev.of_node, i);