linux-kernel - [PATCH v1 2/2] clk: fixed-mmio: Add optional poll for clk readiness

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Message-ID: <20250525190806.1204531-3-edgar.iglesias@gmail.com>
Date: Sun, 25 May 2025 21:08:04 +0200
From: "Edgar E. Iglesias" <edgar.iglesias@...il.com>
To: mturquette@...libre.com,
	sboyd@...nel.org,
	robh@...nel.org,
	krzk+dt@...nel.org,
	conor+dt@...nel.org,
	jank@...ence.com
Cc: edgar.iglesias@....com,
	linux-clk@...r.kernel.org,
	devicetree@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: [PATCH v1 2/2] clk: fixed-mmio: Add optional poll for clk readiness

From: "Edgar E. Iglesias" <edgar.iglesias@....com>

Add optional poll for clk readiness prior to reading the fixed rate.

Signed-off-by: Edgar E. Iglesias <edgar.iglesias@....com>
---
 drivers/clk/clk-fixed-mmio.c | 35 +++++++++++++++++++++++++++++++++++
 1 file changed, 35 insertions(+)

diff --git a/drivers/clk/clk-fixed-mmio.c b/drivers/clk/clk-fixed-mmio.c
index 3bfcf4cd98a2..4b5ba1ad06ac 100644
--- a/drivers/clk/clk-fixed-mmio.c
+++ b/drivers/clk/clk-fixed-mmio.c
@@ -11,10 +11,36 @@
 
 #include <linux/clk-provider.h>
 #include <linux/io.h>
+#include <linux/iopoll.h>
 #include <linux/module.h>
 #include <linux/of_address.h>
 #include <linux/platform_device.h>
 
+static int fixed_mmio_clk_wait_ready(struct device_node *node,
+				     void __iomem *base)
+{
+	u32 ready_mask;
+	u32 ready_val;
+	u32 timeout;
+	u32 v;
+
+	if (of_property_read_u32(node, "ready-timeout", &timeout))
+		timeout = 0;
+
+	if (of_property_read_u32(node, "ready-mask", &ready_mask))
+		ready_mask = ~0;
+
+	if (of_property_read_u32(node, "ready-val", &ready_val)) {
+		pr_err("%pOFn: missing ready-val property\n", node);
+		return -EINVAL;
+	}
+
+	pr_info("%pOFn: wait for clock\n", node);
+	return readl_relaxed_poll_timeout_atomic(base, v,
+						 (v & ready_mask) == ready_val,
+						 1, timeout);
+}
+
 static struct clk_hw *fixed_mmio_clk_setup(struct device_node *node)
 {
 	struct clk_hw *clk;
@@ -23,6 +49,15 @@ static struct clk_hw *fixed_mmio_clk_setup(struct device_node *node)
 	u32 freq;
 	int ret;
 
+	base = of_iomap(node, 1);
+	if (base) {
+		/* Wait for clk to get ready. */
+		ret = fixed_mmio_clk_wait_ready(node, base);
+		iounmap(base);
+		if (ret)
+			return ERR_PTR(ret);
+	}
+
 	base = of_iomap(node, 0);
 	if (!base) {
 		pr_err("%pOFn: failed to map address\n", node);
-- 
2.43.0