drv: detect endianess

Signed-off-by: Federico Vaga <federico.vaga@cern.ch>

drv: detect endianess
Signed-off-by: Federico Vaga <federico.vaga@cern.ch>
0807aac4 · Federico Vaga · 348f96f9 · 0807aac4
Commit 0807aac4 authored Nov 06, 2020 by Federico Vaga
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white-rabbit.c driver/white-rabbit.c +76 -0

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--- a/driver/white-rabbit.c
+++ b/driver/white-rabbit.c
@@ -5,12 +5,88 @@
 */

 #include <linux/module.h>
+#include <linux/device.h>
 #include <linux/platform_device.h>
+#include <linux/errno.h>
+#include <linux/types.h>
+#include <linux/version.h>
 #include "white-rabbit.h"

+#define WR_SIGNATURE 0x0
+#define WR_SIGNATURE_OFFSET 0x0
+
+struct wr_memory_ops {
+	u32 (*read)(void *addr);
+	void (*write)(u32 value, void *addr);
+};
+
+struct wr_dev {
+	struct platform_device *pdev;
+	void __iomem *base;
+	struct wr_memory_ops memops;
+};
+
+static int wr_endianess(struct wr_dev *wr)
+{
+	uint32_t signature;
+
+	signature = ioread32(wr->base + WR_SIGNATURE_OFFSET);
+	if (signature == WR_SIGNATURE)
+		return 0;
+	signature = ioread32be(wr->base + WR_SIGNATURE_OFFSET);
+	if (signature == WR_SIGNATURE)
+		return 1;
+
+	return -1;
+}
+
+static int wr_memops_detect(struct wr_dev *wr)
+{
+	switch (wr_endianess(wr)) {
+	case 0:
+		wr->memops.read = ioread32;
+		wr->memops.write = iowrite32;
+		return 0;
+	case 1:
+		wr->memops.read = ioread32be;
+		wr->memops.write = iowrite32be;
+		return 0;
+	default:
+		dev_err(&wr->pdev->dev, "Invalid endianess\n");
+		return -EINVAL;
+	}
+}
+
 static int wr_probe(struct platform_device *pdev)
 {
+	struct wr_dev *wr;
+	struct resource *res;
+	int err;
+
+        wr = devm_kzalloc(&pdev->dev, sizeof(*wr), GFP_KERNEL);
+	if (!wr)
+		return -ENOMEM;
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+#if KERNEL_VERSION(3, 9, 0) > LINUX_VERSION_CODE
+	wr->base = devm_request_and_ioremap(&pdev->dev, res);
+	if (!wr->base)
+		return -EADDRNOTAVAIL;
+#else
+	wr->base = devm_ioremap_resource(&pdev->dev, res);
+	if (IS_ERR(wr->base))
+		return PTR_ERR(wr->base);
+#endif
+
+	err = wr_memops_detect(wr);
+	if (err)
+		goto err_endianess;
+
 	return 0;
+
+err_endianess:
+	devm_kfree(&pdev->dev, wr);
+	return err;
 }
 static int wr_remove(struct platform_device *pdev)
 {