linux-kernel - [PATCH 1/2] cpufreq: ti-cpufreq: Allow backward compatibility for efuse syscon

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Message-ID: <20240930-b4-ti-cpufreq-am62-quirk-v1-1-b5e04f0f899b@ti.com>
Date: Mon, 30 Sep 2024 15:02:09 +0530
From: Dhruva Gole <d-gole@...com>
To: "Rafael J. Wysocki" <rafael@...nel.org>,
        Viresh Kumar
	<viresh.kumar@...aro.org>
CC: <linux-pm@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        Bryan Brattlof
	<bb@...com>, Nishanth Menon <nm@...com>,
        Andrew Davis <afd@...com>, Dhruva
 Gole <d-gole@...com>
Subject: [PATCH 1/2] cpufreq: ti-cpufreq: Allow backward compatibility for
 efuse syscon

The AM625 syscon for efuse was being taken earlier from the wkup_conf node
where the entire wkup_conf was marked as "syscon". This is wrong and will
be fixed in the devicetree. However, whenever that does happen will end up
breaking this driver for that device because of the change in efuse offset.

Hence, to avoid breaking any sort of backward compatibility of devicetrees
use a quirk to distinguish and accordingly use 0x0 offset for the new
syscon node.

Suggested-by: Nishanth Menon <nm@...com>
Signed-off-by: Dhruva Gole <d-gole@...com>
---
 drivers/cpufreq/ti-cpufreq.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/drivers/cpufreq/ti-cpufreq.c b/drivers/cpufreq/ti-cpufreq.c
index ba621ce1cdda694c98867422dbb7f10c0df2afef..7014cebb41e3490cadd14834e0c3e057419f2abb 100644
--- a/drivers/cpufreq/ti-cpufreq.c
+++ b/drivers/cpufreq/ti-cpufreq.c
@@ -93,6 +93,8 @@ struct ti_cpufreq_soc_data {
 	bool multi_regulator;
 /* Backward compatibility hack: Might have missing syscon */
 #define TI_QUIRK_SYSCON_MAY_BE_MISSING	0x1
+/* Backward compatibility hack: new syscon size is 1 register wide */
+#define TI_QUIRK_SYSCON_IS_SINGLE_REG	0x2
 	u8 quirks;
 };
 
@@ -318,6 +320,7 @@ static struct ti_cpufreq_soc_data am625_soc_data = {
 	.efuse_shift = 0x6,
 	.rev_offset = 0x0014,
 	.multi_regulator = false,
+	.quirks = TI_QUIRK_SYSCON_IS_SINGLE_REG,
 };
 
 static struct ti_cpufreq_soc_data am62a7_soc_data = {
@@ -354,6 +357,10 @@ static int ti_cpufreq_get_efuse(struct ti_cpufreq_data *opp_data,
 
 	ret = regmap_read(opp_data->syscon, opp_data->soc_data->efuse_offset,
 			  &efuse);
+
+	if (opp_data->soc_data->quirks & TI_QUIRK_SYSCON_IS_SINGLE_REG && ret == -EIO)
+		ret = regmap_read(opp_data->syscon, 0x0, &efuse);
+
 	if (opp_data->soc_data->quirks & TI_QUIRK_SYSCON_MAY_BE_MISSING && ret == -EIO) {
 		/* not a syscon register! */
 		void __iomem *regs = ioremap(OMAP3_SYSCON_BASE +

-- 
2.34.1