1 files changed, 71 insertions, 0 deletions
diff --git a/drivers/net/ipa/gsi_reg.c b/drivers/net/ipa/gsi_reg.c
new file mode 100644
index 000000000000..48f81fc24f39
--- /dev/null
+++ b/drivers/net/ipa/gsi_reg.c
@@ -0,0 +1,71 @@
+// SPDX-License-Identifier: GPL-2.0
+
+/* Copyright (C) 2023 Linaro Ltd. */
+
+#include <linux/platform_device.h>
+#include <linux/io.h>
+
+#include "gsi.h"
+#include "gsi_reg.h"
+
+/* GSI EE registers as a group are shifted downward by a fixed constant amount
+ * for IPA versions 4.5 and beyond.  This applies to all GSI registers we use
+ * *except* the ones that disable inter-EE interrupts for channels and event
+ * channels.
+ *
+ * The "raw" (not adjusted) GSI register range is mapped, and a pointer to
+ * the mapped range is held in gsi->virt_raw.  The inter-EE interrupt
+ * registers are accessed using that pointer.
+ *
+ * Most registers are accessed using gsi->virt, which is a copy of the "raw"
+ * pointer, adjusted downward by the fixed amount.
+ */
+#define GSI_EE_REG_ADJUST	0x0000d000			/* IPA v4.5+ */
+
+/* Sets gsi->virt_raw and gsi->virt, and I/O maps the "gsi" memory range */
+int gsi_reg_init(struct gsi *gsi, struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct resource *res;
+	resource_size_t size;
+	u32 adjust;
+
+	/* Get GSI memory range and map it */
+	res = platform_get_resource_byname(pdev, IORESOURCE_MEM, "gsi");
+	if (!res) {
+		dev_err(dev, "DT error getting \"gsi\" memory property\n");
+		return -ENODEV;
+	}
+
+	size = resource_size(res);
+	if (res->start > U32_MAX || size > U32_MAX - res->start) {
+		dev_err(dev, "DT memory resource \"gsi\" out of range\n");
+		return -EINVAL;
+	}
+
+	/* Make sure we can make our pointer adjustment if necessary */
+	adjust = gsi->version < IPA_VERSION_4_5 ? 0 : GSI_EE_REG_ADJUST;
+	if (res->start < adjust) {
+		dev_err(dev, "DT memory resource \"gsi\" too low (< %u)\n",
+			adjust);
+		return -EINVAL;
+	}
+
+	gsi->virt_raw = ioremap(res->start, size);
+	if (!gsi->virt_raw) {
+		dev_err(dev, "unable to remap \"gsi\" memory\n");
+		return -ENOMEM;
+	}
+	/* Most registers are accessed using an adjusted register range */
+	gsi->virt = gsi->virt_raw - adjust;
+
+	return 0;
+}
+
+/* Inverse of gsi_reg_init() */
+void gsi_reg_exit(struct gsi *gsi)
+{
+	gsi->virt = NULL;
+	iounmap(gsi->virt_raw);
+	gsi->virt_raw = NULL;
+}