net: microchip: add FDMA library

Add new FDMA library for interacting with the FDMA engine on Microchip
Sparx5 and lan966x switch chips, in an effort to reduce duplicate code
and provide a common set of symbols and functions.

Signed-off-by: Daniel Machon <daniel.machon@microchip.com>
Reviewed-by: Steen Hegelund <Steen.Hegelund@microchip.com>
Reviewed-by: Jens Emil Schulz Østergaard <jensemil.schulzostergaard@microchip.com>
Reviewed-by: Horatiu Vultur <horatiu.vultur@microchip.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/microchip/Kconfig

@@ -59,5 +59,6 @@ config LAN743X
 source "drivers/net/ethernet/microchip/lan966x/Kconfig"
 source "drivers/net/ethernet/microchip/sparx5/Kconfig"
 source "drivers/net/ethernet/microchip/vcap/Kconfig"
+source "drivers/net/ethernet/microchip/fdma/Kconfig"
 
 endif # NET_VENDOR_MICROCHIP

drivers/net/ethernet/microchip/Makefile

@@ -12,3 +12,4 @@ lan743x-objs := lan743x_main.o lan743x_ethtool.o lan743x_ptp.o
 obj-$(CONFIG_LAN966X_SWITCH) += lan966x/
 obj-$(CONFIG_SPARX5_SWITCH) += sparx5/
 obj-$(CONFIG_VCAP) += vcap/
+obj-$(CONFIG_FDMA) += fdma/

drivers/net/ethernet/microchip/fdma/Kconfig

@@ -0,0 +1,18 @@
+# SPDX-License-Identifier: GPL-2.0-only
+#
+# Microchip FDMA API configuration
+#
+
+if NET_VENDOR_MICROCHIP
+
+config FDMA
+	bool "FDMA API"
+	help
+	  Provides the basic FDMA functionality for multiple Microchip
+	  switchcores.
+
+	  Say Y here if you want to build the FDMA API that provides a common
+	  set of functions and data structures for interacting with the Frame
+	  DMA engine in multiple microchip switchcores.
+
+endif # NET_VENDOR_MICROCHIP

drivers/net/ethernet/microchip/fdma/Makefile

@@ -0,0 +1,7 @@
+# SPDX-License-Identifier: GPL-2.0-only
+#
+# Makefile for Microchip FDMA
+#
+
+obj-$(CONFIG_FDMA) += fdma.o
+fdma-y += fdma_api.o

drivers/net/ethernet/microchip/fdma/fdma_api.c

@@ -0,0 +1,146 @@
+// SPDX-License-Identifier: GPL-2.0+
+
+#include "fdma_api.h"
+
+#include <linux/bits.h>
+#include <linux/etherdevice.h>
+#include <linux/types.h>
+
+/* Add a DB to a DCB, providing a callback for getting the DB dataptr. */
+static int __fdma_db_add(struct fdma *fdma, int dcb_idx, int db_idx, u64 status,
+			 int (*cb)(struct fdma *fdma, int dcb_idx,
+				   int db_idx, u64 *dataptr))
+{
+	struct fdma_db *db = fdma_db_get(fdma, dcb_idx, db_idx);
+
+	db->status = status;
+
+	return cb(fdma, dcb_idx, db_idx, &db->dataptr);
+}
+
+/* Add a DB to a DCB, using the callback set in the fdma_ops struct. */
+int fdma_db_add(struct fdma *fdma, int dcb_idx, int db_idx, u64 status)
+{
+	return __fdma_db_add(fdma,
+			     dcb_idx,
+			     db_idx,
+			     status,
+			     fdma->ops.dataptr_cb);
+}
+
+/* Add a DCB with callbacks for getting the DB dataptr and the DCB nextptr. */
+int __fdma_dcb_add(struct fdma *fdma, int dcb_idx, u64 info, u64 status,
+		   int (*dcb_cb)(struct fdma *fdma, int dcb_idx, u64 *nextptr),
+		   int (*db_cb)(struct fdma *fdma, int dcb_idx, int db_idx,
+				u64 *dataptr))
+{
+	struct fdma_dcb *dcb = fdma_dcb_get(fdma, dcb_idx);
+	int i, err;
+
+	for (i = 0; i < fdma->n_dbs; i++) {
+		err = __fdma_db_add(fdma, dcb_idx, i, status, db_cb);
+		if (unlikely(err))
+			return err;
+	}
+
+	err = dcb_cb(fdma, dcb_idx, &fdma->last_dcb->nextptr);
+	if (unlikely(err))
+		return err;
+
+	fdma->last_dcb = dcb;
+
+	dcb->nextptr = FDMA_DCB_INVALID_DATA;
+	dcb->info = info;
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(__fdma_dcb_add);
+
+/* Add a DCB, using the preset callbacks in the fdma_ops struct. */
+int fdma_dcb_add(struct fdma *fdma, int dcb_idx, u64 info, u64 status)
+{
+	return __fdma_dcb_add(fdma,
+			      dcb_idx,
+			      info, status,
+			      fdma->ops.nextptr_cb,
+			      fdma->ops.dataptr_cb);
+}
+EXPORT_SYMBOL_GPL(fdma_dcb_add);
+
+/* Initialize the DCB's and DB's. */
+int fdma_dcbs_init(struct fdma *fdma, u64 info, u64 status)
+{
+	int i, err;
+
+	fdma->last_dcb = fdma->dcbs;
+	fdma->db_index = 0;
+	fdma->dcb_index = 0;
+
+	for (i = 0; i < fdma->n_dcbs; i++) {
+		err = fdma_dcb_add(fdma, i, info, status);
+		if (err)
+			return err;
+	}
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(fdma_dcbs_init);
+
+/* Allocate coherent DMA memory for FDMA. */
+int fdma_alloc_coherent(struct device *dev, struct fdma *fdma)
+{
+	fdma->dcbs = dma_alloc_coherent(dev,
+					fdma->size,
+					&fdma->dma,
+					GFP_KERNEL);
+	if (!fdma->dcbs)
+		return -ENOMEM;
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(fdma_alloc_coherent);
+
+/* Allocate physical memory for FDMA. */
+int fdma_alloc_phys(struct fdma *fdma)
+{
+	fdma->dcbs = kzalloc(fdma->size, GFP_KERNEL);
+	if (!fdma->dcbs)
+		return -ENOMEM;
+
+	fdma->dma = virt_to_phys(fdma->dcbs);
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(fdma_alloc_phys);
+
+/* Free coherent DMA memory. */
+void fdma_free_coherent(struct device *dev, struct fdma *fdma)
+{
+	dma_free_coherent(dev, fdma->size, fdma->dcbs, fdma->dma);
+}
+EXPORT_SYMBOL_GPL(fdma_free_coherent);
+
+/* Free virtual memory. */
+void fdma_free_phys(struct fdma *fdma)
+{
+	kfree(fdma->dcbs);
+}
+EXPORT_SYMBOL_GPL(fdma_free_phys);
+
+/* Get the size of the FDMA memory */
+u32 fdma_get_size(struct fdma *fdma)
+{
+	return ALIGN(sizeof(struct fdma_dcb) * fdma->n_dcbs, PAGE_SIZE);
+}
+EXPORT_SYMBOL_GPL(fdma_get_size);
+
+/* Get the size of the FDMA memory. This function is only applicable if the
+ * dataptr addresses and DCB's are in contiguous memory.
+ */
+u32 fdma_get_size_contiguous(struct fdma *fdma)
+{
+	return ALIGN(fdma->n_dcbs * sizeof(struct fdma_dcb) +
+		     fdma->n_dcbs * fdma->n_dbs * fdma->db_size,
+		     PAGE_SIZE);
+}
+EXPORT_SYMBOL_GPL(fdma_get_size_contiguous);