linux-kernel - [PATCH 1/3] soc: samsung: exynos-pmu: allow specifying read & write access tables for secure regmap

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Message-Id: <20251002-gs101-pmu-regmap-tables-v1-1-1f96f0920eb3@linaro.org>
Date: Thu, 02 Oct 2025 11:32:57 +0100
From: André Draszik <andre.draszik@...aro.org>
To: Krzysztof Kozlowski <krzk@...nel.org>, 
 Alim Akhtar <alim.akhtar@...sung.com>, 
 Peter Griffin <peter.griffin@...aro.org>, 
 Tudor Ambarus <tudor.ambarus@...aro.org>
Cc: Will McVicker <willmcvicker@...gle.com>, kernel-team@...roid.com, 
 linux-arm-kernel@...ts.infradead.org, linux-samsung-soc@...r.kernel.org, 
 linux-kernel@...r.kernel.org, 
 André Draszik <andre.draszik@...aro.org>
Subject: [PATCH 1/3] soc: samsung: exynos-pmu: allow specifying read &
 write access tables for secure regmap

Accessing non-existent PMU registers causes an SError, halting the
system.

regmap can help us with that by allowing to pass the list of valid
registers as part of the config during creation. When this driver
creates a new regmap itself rather than relying on
syscon_node_to_regmap(), it's therefore easily possible to hook in
custom access tables for valid read and write registers.

Specifying access tables avoids SErrors for invalid registers and
instead the regmap core can just return an error. Outside drivers, this
is also helpful when using debugfs to access the regmap.

Make it possible for drivers to specify read and write tables to be
used on creation of the secure regmap.

Signed-off-by: André Draszik <andre.draszik@...aro.org>
---
 drivers/soc/samsung/exynos-pmu.c | 3 +++
 drivers/soc/samsung/exynos-pmu.h | 4 ++++
 2 files changed, 7 insertions(+)

diff --git a/drivers/soc/samsung/exynos-pmu.c b/drivers/soc/samsung/exynos-pmu.c
index 22c50ca2aa79bf1945255ee6cc7443d7309b2573..9f416de03610b1727d8cc77616e5c87e2525cc69 100644
--- a/drivers/soc/samsung/exynos-pmu.c
+++ b/drivers/soc/samsung/exynos-pmu.c
@@ -635,6 +635,9 @@ static int exynos_pmu_probe(struct platform_device *pdev)
 		pmu_regmcfg = regmap_smccfg;
 		pmu_regmcfg.max_register = resource_size(res) -
 					   pmu_regmcfg.reg_stride;
+		pmu_regmcfg.wr_table = pmu_context->pmu_data->wr_table;
+		pmu_regmcfg.rd_table = pmu_context->pmu_data->rd_table;
+
 		/* Need physical address for SMC call */
 		regmap = devm_regmap_init(dev, NULL,
 					  (void *)(uintptr_t)res->start,
diff --git a/drivers/soc/samsung/exynos-pmu.h b/drivers/soc/samsung/exynos-pmu.h
index 0938bb4fe15f439e2d8bddeec51b6077e79a7e84..113149ed32c88a09b075be82050c26970e4c0620 100644
--- a/drivers/soc/samsung/exynos-pmu.h
+++ b/drivers/soc/samsung/exynos-pmu.h
@@ -27,6 +27,10 @@ struct exynos_pmu_data {
 	void (*pmu_init)(void);
 	void (*powerdown_conf)(enum sys_powerdown);
 	void (*powerdown_conf_extra)(enum sys_powerdown);
+
+	/* for the pmu_secure case */
+	const struct regmap_access_table *rd_table;
+	const struct regmap_access_table *wr_table;
 };
 
 extern void __iomem *pmu_base_addr;

-- 
2.51.0.618.g983fd99d29-goog