linux-kernel - [PATCH 2/2] cpufreq: qcom-hw: Ensure only freq-domain regs are counted in num

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Message-Id: <20230111205125.1860858-2-konrad.dybcio@linaro.org>
Date:   Wed, 11 Jan 2023 21:51:25 +0100
From:   Konrad Dybcio <konrad.dybcio@...aro.org>
To:     linux-arm-msm@...r.kernel.org, andersson@...nel.org,
        agross@...nel.org, krzysztof.kozlowski@...aro.org
Cc:     marijn.suijten@...ainline.org,
        Konrad Dybcio <konrad.dybcio@...aro.org>,
        "Rafael J. Wysocki" <rafael@...nel.org>,
        Viresh Kumar <viresh.kumar@...aro.org>,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Manivannan Sadhasivam <mani@...nel.org>,
        linux-pm@...r.kernel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH 2/2] cpufreq: qcom-hw: Ensure only freq-domain regs are counted in num_domains

In preparation for CPRh-aware OSM programming, change the probe
function so that we determine the number of frequency domains by
counting the number of reg-names entries that begin with
"freq-domain", as the aforementioned changes require introduction
of non-freq-domain register spaces.

Fixes: 1a6a8b0080b0 ("cpufreq: qcom-hw: Fix reading "reg" with address/size-cells != 2")
Fixes: 054a3ef683a1 ("cpufreq: qcom-hw: Allocate qcom_cpufreq_data during probe")
Signed-off-by: Konrad Dybcio <konrad.dybcio@...aro.org>
---
 drivers/cpufreq/qcom-cpufreq-hw.c | 34 ++++++++++++++++++++++---------
 1 file changed, 24 insertions(+), 10 deletions(-)

diff --git a/drivers/cpufreq/qcom-cpufreq-hw.c b/drivers/cpufreq/qcom-cpufreq-hw.c
index 9505a812d6a1..89d5ed267399 100644
--- a/drivers/cpufreq/qcom-cpufreq-hw.c
+++ b/drivers/cpufreq/qcom-cpufreq-hw.c
@@ -651,8 +651,9 @@ static int qcom_cpufreq_hw_driver_probe(struct platform_device *pdev)
 	struct device *dev = &pdev->dev;
 	struct device_node *soc_node;
 	struct device *cpu_dev;
+	const char *reg_name;
 	struct clk *clk;
-	int ret, i, num_domains, reg_sz;
+	int ret, i, num_reg_names, num_domains = 0;
 
 	clk = clk_get(dev, "xo");
 	if (IS_ERR(clk))
@@ -684,19 +685,32 @@ static int qcom_cpufreq_hw_driver_probe(struct platform_device *pdev)
 	if (!soc_node)
 		return -EINVAL;
 
-	ret = of_property_read_u32(soc_node, "#address-cells", &reg_sz);
-	if (ret)
+	num_reg_names = of_property_count_strings(dev->of_node, "reg-names");
+	if (num_reg_names <= 0) {
+		ret = num_reg_names ? num_reg_names : -ENODATA;
 		goto of_exit;
+	}
 
-	ret = of_property_read_u32(soc_node, "#size-cells", &i);
-	if (ret)
-		goto of_exit;
+	for (i = 0; i < num_reg_names; i++) {
+		ret = of_property_read_string_index(dev->of_node, "reg-names", i, &reg_name);
+		if (ret < 0)
+			goto of_exit;
 
-	reg_sz += i;
+		/*
+		 * Check if the i-th reg is a freq-domain base, no need to add 1
+		 * more byte for idx, as sizeof counts \0 whereas strlen does not.
+		 */
+		if (strlen(reg_name) == sizeof("freq-domain")) {
+			/* Check if this reg-name begins with "freq-domain" */
+			if (!strncmp(reg_name, "freq-domain", sizeof("freq-domain") - 1))
+				num_domains++;
+		}
+	}
 
-	num_domains = of_property_count_elems_of_size(dev->of_node, "reg", sizeof(u32) * reg_sz);
-	if (num_domains <= 0)
-		return num_domains;
+	if (num_domains <= 0) {
+		ret = -EINVAL;
+		goto of_exit;
+	}
 
 	qcom_cpufreq.data = devm_kzalloc(dev, sizeof(struct qcom_cpufreq_data) * num_domains,
 					 GFP_KERNEL);
-- 
2.39.0