[RFC PATCH v4 2/9] accel: rocket: Derive DMA width and core count from match data

[MidG971 <midgy971@gmail.com>]

From: Midgy BALON <midgy971@gmail.com>

The probe already has the per-SoC match data, which now records the core
count and DMA width.  Use it for the cores array allocation and the
device DMA mask instead of re-scanning the device tree for available core
nodes.

While at it, reject a device tree that declares more NPU core nodes than
the SoC has, so the fixed-size cores array can never be overrun.

Signed-off-by: Midgy BALON <midgy971@gmail.com>
---
 drivers/accel/rocket/rocket_core.h   |  2 ++
 drivers/accel/rocket/rocket_device.c | 15 +++++----------
 drivers/accel/rocket/rocket_device.h |  3 ++-
 drivers/accel/rocket/rocket_drv.c    | 13 ++++++++++++-
 4 files changed, 21 insertions(+), 12 deletions(-)

diff --git a/drivers/accel/rocket/rocket_core.h b/drivers/accel/rocket/rocket_core.h
index 8ee105a0be40e..d6421251670dc 100644
--- a/drivers/accel/rocket/rocket_core.h
+++ b/drivers/accel/rocket/rocket_core.h
@@ -16,9 +16,11 @@ struct rocket_core;
 
 /**
  * struct rocket_soc_data - per-SoC configuration data
+ * @num_cores: Number of NPU cores in this SoC.
  * @dma_bits: Physical address width reachable by the NPU's AXI master.
  */
 struct rocket_soc_data {
+	unsigned int num_cores;
 	unsigned int dma_bits;
 };
 
diff --git a/drivers/accel/rocket/rocket_device.c b/drivers/accel/rocket/rocket_device.c
index 46e6ee1e72c5f..6186f4faa3a2a 100644
--- a/drivers/accel/rocket/rocket_device.c
+++ b/drivers/accel/rocket/rocket_device.c
@@ -6,18 +6,16 @@
 #include <linux/clk.h>
 #include <linux/dma-mapping.h>
 #include <linux/platform_device.h>
-#include <linux/of.h>
 
 #include "rocket_device.h"
 
 struct rocket_device *rocket_device_init(struct platform_device *pdev,
-					 const struct drm_driver *rocket_drm_driver)
+					 const struct drm_driver *rocket_drm_driver,
+					 const struct rocket_soc_data *soc_data)
 {
 	struct device *dev = &pdev->dev;
-	struct device_node *core_node;
 	struct rocket_device *rdev;
 	struct drm_device *ddev;
-	unsigned int num_cores = 0;
 	int err;
 
 	rdev = devm_drm_dev_alloc(dev, rocket_drm_driver, struct rocket_device, ddev);
@@ -27,17 +25,14 @@ struct rocket_device *rocket_device_init(struct platform_device *pdev,
 	ddev = &rdev->ddev;
 	dev_set_drvdata(dev, rdev);
 
-	for_each_compatible_node(core_node, NULL, "rockchip,rk3588-rknn-core")
-		if (of_device_is_available(core_node))
-			num_cores++;
-
-	rdev->cores = devm_kcalloc(dev, num_cores, sizeof(*rdev->cores), GFP_KERNEL);
+	rdev->cores = devm_kcalloc(dev, soc_data->num_cores, sizeof(*rdev->cores),
+				   GFP_KERNEL);
 	if (!rdev->cores)
 		return ERR_PTR(-ENOMEM);
 
 	dma_set_max_seg_size(dev, UINT_MAX);
 
-	err = dma_set_mask_and_coherent(dev, DMA_BIT_MASK(40));
+	err = dma_set_mask_and_coherent(dev, DMA_BIT_MASK(soc_data->dma_bits));
 	if (err)
 		return ERR_PTR(err);
 
diff --git a/drivers/accel/rocket/rocket_device.h b/drivers/accel/rocket/rocket_device.h
index ce662abc01d3d..2f74e078974e3 100644
--- a/drivers/accel/rocket/rocket_device.h
+++ b/drivers/accel/rocket/rocket_device.h
@@ -22,7 +22,8 @@ struct rocket_device {
 };
 
 struct rocket_device *rocket_device_init(struct platform_device *pdev,
-					 const struct drm_driver *rocket_drm_driver);
+					 const struct drm_driver *rocket_drm_driver,
+					 const struct rocket_soc_data *soc_data);
 void rocket_device_fini(struct rocket_device *rdev);
 #define to_rocket_device(drm_dev) \
 	((struct rocket_device *)(container_of((drm_dev), struct rocket_device, ddev)))
diff --git a/drivers/accel/rocket/rocket_drv.c b/drivers/accel/rocket/rocket_drv.c
index 384c38e13acce..f0beed2d522c7 100644
--- a/drivers/accel/rocket/rocket_drv.c
+++ b/drivers/accel/rocket/rocket_drv.c
@@ -159,11 +159,15 @@ static const struct drm_driver rocket_drm_driver = {
 
 static int rocket_probe(struct platform_device *pdev)
 {
+	const struct rocket_soc_data *soc_data = of_device_get_match_data(&pdev->dev);
 	int ret;
 
+	if (!soc_data)
+		return -EINVAL;
+
 	if (rdev == NULL) {
 		/* First core probing, initialize DRM device. */
-		rdev = rocket_device_init(drm_dev, &rocket_drm_driver);
+		rdev = rocket_device_init(drm_dev, &rocket_drm_driver, soc_data);
 		if (IS_ERR(rdev)) {
 			dev_err(&pdev->dev, "failed to initialize rocket device\n");
 			return PTR_ERR(rdev);
@@ -172,6 +176,12 @@ static int rocket_probe(struct platform_device *pdev)
 
 	unsigned int core = rdev->num_cores;
 
+	if (core >= soc_data->num_cores) {
+		dev_err(&pdev->dev, "too many NPU core nodes (max %u)\n",
+			soc_data->num_cores);
+		return -EINVAL;
+	}
+
 	dev_set_drvdata(&pdev->dev, rdev);
 
 	rdev->cores[core].rdev = rdev;
@@ -214,6 +224,7 @@ static void rocket_remove(struct platform_device *pdev)
 }
 
 static const struct rocket_soc_data rk3588_soc_data = {
+	.num_cores = 3,
 	.dma_bits = 40,
 };
 
-- 
2.39.5