linux-kernel - [PATCH 4/4] pmdomain: mediatek: mtk-mfg: Expose shader

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Message-Id: <20251217-mt8196-shader-present-v1-4-f6f8f3aa1e93@collabora.com>
Date: Wed, 17 Dec 2025 18:03:30 +0100
From: Nicolas Frattaroli <nicolas.frattaroli@...labora.com>
To: Boris Brezillon <boris.brezillon@...labora.com>, 
 Steven Price <steven.price@....com>, Liviu Dudau <liviu.dudau@....com>, 
 Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>, 
 Maxime Ripard <mripard@...nel.org>, Thomas Zimmermann <tzimmermann@...e.de>, 
 David Airlie <airlied@...il.com>, Simona Vetter <simona@...ll.ch>, 
 Rob Herring <robh@...nel.org>, Krzysztof Kozlowski <krzk+dt@...nel.org>, 
 Conor Dooley <conor+dt@...nel.org>, 
 Matthias Brugger <matthias.bgg@...il.com>, 
 AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>, 
 Ulf Hansson <ulf.hansson@...aro.org>
Cc: Chen-Yu Tsai <wenst@...omium.org>, Chia-I Wu <olvaffe@...il.com>, 
 kernel@...labora.com, dri-devel@...ts.freedesktop.org, 
 devicetree@...r.kernel.org, linux-kernel@...r.kernel.org, 
 linux-arm-kernel@...ts.infradead.org, linux-mediatek@...ts.infradead.org, 
 linux-pm@...r.kernel.org, 
 Nicolas Frattaroli <nicolas.frattaroli@...labora.com>
Subject: [PATCH 4/4] pmdomain: mediatek: mtk-mfg: Expose shader_present as
 nvmem cell

Implement nvmem-provider functionality in mtk-mfg-pmdomain, such that it
can expose its GF_REG_SHADER_PRESENT value in the shared memory as an
nvmem cell for panthor.

Signed-off-by: Nicolas Frattaroli <nicolas.frattaroli@...labora.com>
---
 drivers/pmdomain/mediatek/mtk-mfg-pmdomain.c | 57 ++++++++++++++++++++++++++++
 1 file changed, 57 insertions(+)

diff --git a/drivers/pmdomain/mediatek/mtk-mfg-pmdomain.c b/drivers/pmdomain/mediatek/mtk-mfg-pmdomain.c
index 9bad577b3ae4..725ebc678f1b 100644
--- a/drivers/pmdomain/mediatek/mtk-mfg-pmdomain.c
+++ b/drivers/pmdomain/mediatek/mtk-mfg-pmdomain.c
@@ -10,6 +10,7 @@
 #include <linux/clk-provider.h>
 #include <linux/container_of.h>
 #include <linux/iopoll.h>
+#include <linux/nvmem-provider.h>
 #include <linux/mailbox_client.h>
 #include <linux/module.h>
 #include <linux/of.h>
@@ -872,6 +873,58 @@ static int mtk_mfg_init_clk_provider(struct mtk_mfg *mfg)
 	return 0;
 }
 
+static int mtk_mfg_read_nvmem(void *priv, unsigned int offset, void *val, size_t bytes)
+{
+	struct mtk_mfg *mfg = priv;
+	u32 *buf = val;
+
+	if (bytes != 4)
+		return -EINVAL;
+
+	if (!mfg->shared_mem)
+		return -ENODEV;
+
+	if (offset + bytes >= mfg->shared_mem_size)
+		return -EINVAL;
+
+	*buf = readl(mfg->shared_mem + offset);
+
+	return 0;
+}
+
+static int mtk_mfg_init_nvmem_provider(struct mtk_mfg *mfg)
+{
+	struct device *dev = &mfg->pdev->dev;
+	struct nvmem_cell_info cell = {};
+	struct nvmem_config config = {};
+	struct nvmem_device *nvdev;
+	int ret;
+
+	config.reg_read = mtk_mfg_read_nvmem;
+	config.dev = dev;
+	config.read_only = true;
+	config.priv = mfg;
+	config.size = 4;
+	config.word_size = 4;
+
+	nvdev = devm_nvmem_register(dev, &config);
+	of_node_put(config.of_node);
+	if (IS_ERR(nvdev))
+		return dev_err_probe(dev, PTR_ERR(nvdev), "Couldn't register nvmem provider\n");
+
+	cell.name = "shader-present";
+	cell.offset = GF_REG_SHADER_PRESENT;
+	cell.bytes = 4;
+	cell.np = of_get_child_by_name(dev->of_node, cell.name);
+
+	ret = nvmem_add_one_cell(nvdev, &cell);
+	/* cell.np purposefully not put as nvmem_add_one_cell does not increase refcount */
+	if (ret)
+		return dev_err_probe(dev, ret, "Couldn't add cell %s\n", cell.name);
+
+	return 0;
+}
+
 static int mtk_mfg_probe(struct platform_device *pdev)
 {
 	struct mtk_mfg *mfg;
@@ -984,6 +1037,10 @@ static int mtk_mfg_probe(struct platform_device *pdev)
 	if (ret)
 		goto err_power_off;
 
+	ret = mtk_mfg_init_nvmem_provider(mfg);
+	if (ret)
+		goto err_power_off;
+
 	ret = of_genpd_add_provider_simple(dev->of_node, &mfg->pd);
 	if (ret) {
 		dev_err_probe(dev, ret, "Failed to add pmdomain provider\n");

-- 
2.52.0