dmaengine: fsl-edma: extract common fsl-edma code (no changes in behavior intended)

Quoted 139 lines · Angelo Dureghello

Hi Stefan,

i am about to post a v9 in short.

Quoted 120 lines · Stefan Agner

Quoted 94 lines · Krzysztof Kozlowski

Quoted 93 lines · Stefan Agner

Quoted 76 lines · Angelo Dureghello

This patch adds a new fsl-edma-common module to allow new mcf-edma module code to use most of the fsl-edma code.

Signed-off-by Angelo Dureghello <[email protected]>

---
Changes for v2:
- patch splitted into 4
- add mcf-edma as minimal different parts from fsl-edma

Changes for v3:
none

Changes for v4:
- patch simplified from 4/4 into 2/2
- collecting all the mcf-edma-related changes

Changes for v5:
none

Changes for v6:
- adjusted comment header
- fixed bit shift with BIT()
- we need to free the interrupts at remove(), so removed all devm_ interrupt related calls

Changes for v7:
none

Changes for v8:
- patch rewritten from scratch, splitted into 3, common code isolated, minimal changes from the original Freescale code have been done. The patch has been tested with both Iris + Colibri Vybrid VF50 and stmark2/mcf54415 Coldfire boards.

---
 drivers/dma/Makefile          |   2 +-
 drivers/dma/fsl-edma-common.c | 576 ++++++++++++++++++++++++++++
 drivers/dma/fsl-edma-common.h | 196 ++++++++++
 drivers/dma/fsl-edma.c        | 697 +---------------------------------
 4 files changed, 774 insertions(+), 697 deletions(-)
 create mode 100644 drivers/dma/fsl-edma-common.c
 create mode 100644 drivers/dma/fsl-edma-common.h

drivers/dma/Makefile +1 -1

index 203a99d68315..66022f59fca4 100644
@@ -31,7 +31,7 @@ obj-$(CONFIG_DW_AXI_DMAC) += dw-axi-dmac/
 obj-$(CONFIG_DW_DMAC_CORE) += dw/
 obj-$(CONFIG_EP93XX_DMA) += ep93xx_dma.o
 obj-$(CONFIG_FSL_DMA) += fsldma.o
-obj-$(CONFIG_FSL_EDMA) += fsl-edma.o
+obj-$(CONFIG_FSL_EDMA) += fsl-edma.o fsl-edma-common.o
 obj-$(CONFIG_FSL_RAID) += fsl_raid.o
 obj-$(CONFIG_HSU_DMA) += hsu/
 obj-$(CONFIG_IMG_MDC_DMA) += img-mdc-dma.o

drivers/dma/fsl-edma-common.c new file +15 -0

new file mode 100644
index 000000000000..0ae7094f477a
@@ -0,0 +1,576 @@
+// SPDX-License-Identifier: GPL-2.0
+//
+// Copyright (c) 2013-2014 Freescale Semiconductor, Inc
+// Copyright (c) 2017 Sysam, Angelo Dureghello  <[email protected]>
+
+#include <linux/dmapool.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+
+#include "fsl-edma-common.h"
+
+/*
+ * R/W functions for big- or little-endian registers:
+ * The eDMA controller's endian is independent of the CPU core's endian.
+ * For the big-endian IP module, the offset for 8-bit or 16-bit registers

drivers/dma/fsl-edma-common.c line 25

Quoted 10 lines

drivers/dma/fsl-edma-common.c new file +10 -0

+ * should also be swapped opposite to that in little-endian IP.
+ */
+u32 edma_readl(struct fsl_edma_engine *edma, void __iomem *addr)
+{
+     if (edma->big_endian)
+             return ioread32be(addr);
+     else
+             return ioread32(addr);
+}
+EXPORT_SYMBOL_GPL(edma_readl);

In 3/3 you link the common object into the two modules individually:

obj-$(CONFIG_FSL_EDMA) += fsl-edma.o fsl-edma-common.o obj-$(CONFIG_MCF_EDMA) += mcf-edma.o fsl-edma-common.o

Quoted 6 lines

Quoted 3 lines

Therefor you do not access those functions from another module (they are within the module). No exporting should be necessary. Drop all those exports.

The fsl-edma-common will be its own module so the exports are necessary for proper linking/modpost.

Hm, oh I see, I got that wrong.

We could use
fsl-edma-all-y = fsl-edma.o fsl-edma-common.o
obj-$(CONFIG_FSL_EDMA) += fsl-edma-all.o
mcf-edma-all-y = mcf-edma.o fsl-edma-common.o
obj-$(CONFIG_MCF_EDMA) += mcf-edma-all.o

to create two modules but that duplicates some code. It probably wouldn't matter in practise since the two IPs are used on different architecture...

However, if we stay with the three modules approach, we should introduce a hidden config symbol, e.g.

config FSL_EDMA_COMMON
tristate

Quoted 9 lines

In FSL_EDMA/MCF_EDMA use
select FSL_EDMA_COMMON

And in the Makefile obj-$(CONFIG_FSL_EDMA_COMMON) += fsl-edma-common.o obj-$(CONFIG_FSL_EDMA) += fsl-edma.o obj-$(CONFIG_MCF_EDMA) += mcf-edma.o

There was already a discussion with Vinod and Geert on this, and i finally previously changed things in this way

obj-$(CONFIG_FSL_EDMA) += fsl-edma.o fsl-edma-common.o

Quoted 8 lines

The idea was to simplify things avoiding to use an additional config symbol, as i did initially. It's a common pattern in several Makefiles (e.g.drivers/net/ethernet/8390/Makefile and drivers/scsi/Makefile).
Also we have a single common code part since obj-y is a list, and IIRC it's filtered for duplicates.
So if can be ok for you too, i would not roll back again.

I see, you refer to this discussion:
https://www.spinics.net/lists/dmaengine/msg15863.html

Should have followed up on those discussions, sorry. Leave it as is then.

Quoted 11 lines

Quoted 6 lines

However, I do not like that the compiler can no longer inline simple acesors like edma_(readl|writel). So if we stay with the three modules approach then move at least the accesors and to_fsl_edma_chan/to_fsl_edma_desc as inline functions to the header file.

I agree too, my initial patch was a single separate driver. But it resulted in too much duplicated code, so a common module has been required. Btw, seems i cannot inline those functions. fsl-edma-common.h is included from both fsl-edma-common.c and mcf/fsl-edma.c resulting in multiple definitions linking error.

I agree, we should introduce the common module and share as much as possible.

Just those small accessors typically get inlined by the compiler, and often collapse completely in optimization phases (e.g. a function call has more overhead than just inlining them, making resulting code smaller and faster).

Just define them as static inline, then it won't lead to linking errors.

I tried with this change in fsl-edma-common.h (and remove them from fsl-edma-common.c):

(quoted diff) +0 -2

-u32 edma_readl(struct fsl_edma_engine *edma, void __iomem *addr);
-void edma_writeb(struct fsl_edma_engine *edma, u8 val, void __iomem

*addr);
-void edma_writew(struct fsl_edma_engine *edma, u16 val, void __iomem *addr);
-void edma_writel(struct fsl_edma_engine *edma, u32 val, void __iomem *addr);

(quoted diff) +3 -3

-
-struct fsl_edma_chan *to_fsl_edma_chan(struct dma_chan *chan);
-struct fsl_edma_desc *to_fsl_edma_desc(struct virt_dma_desc *vd);
+/*
+ * R/W functions for big- or little-endian registers:
+ * The eDMA controller's endian is independent of the CPU core's

endian.
+ * For the big-endian IP module, the offset for 8-bit or 16-bit registers
+ * should also be swapped opposite to that in little-endian IP.
+ */
+static inline u32 edma_readl(struct fsl_edma_engine *edma, void __iomem *addr)

(quoted diff) +8 -0

+{
+       if (edma->big_endian)
+               return ioread32be(addr);
+       else
+               return ioread32(addr);
+}
+
+static inline void edma_writeb(struct fsl_edma_engine *edma, u8 val,

void __iomem *addr)

(quoted diff) +4 -0

+{
+       /* swap the reg offset for these in big-endian mode */
+       if (edma->big_endian)
+               iowrite8(val, (void __iomem *)((unsigned long)addr ^

0x3));

(quoted diff) +5 -0

+       else
+               iowrite8(val, addr);
+}
+
+static inline void edma_writew(struct fsl_edma_engine *edma, u16 val,

void __iomem *addr)

(quoted diff) +4 -0

+{
+       /* swap the reg offset for these in big-endian mode */
+       if (edma->big_endian)
+               iowrite16be(val, (void __iomem *)((unsigned long)addr ^

0x2));

(quoted diff) +5 -0

+       else
+               iowrite16(val, addr);
+}
+
+static inline void edma_writel(struct fsl_edma_engine *edma, u32 val,

void __iomem *addr)

(quoted diff) +8 -0

+{
+       if (edma->big_endian)
+               iowrite32be(val, addr);
+       else
+               iowrite32(val, addr);
+}
+
+static inline struct fsl_edma_chan *to_fsl_edma_chan(struct dma_chan

*chan)

(quoted diff) +5 -0

+{
+       return container_of(chan, struct fsl_edma_chan, vchan.chan);
+}
+
+static inline struct fsl_edma_desc *to_fsl_edma_desc(struct

virt_dma_desc *vd)

(quoted diff) +3 -0

+{
+       return container_of(vd, struct fsl_edma_desc, vdesc);
+}

All three kernel modules end up being smaller (overall more than 1kB), so the compiler really does its magic.

Quoted 5 lines

Mainly until v7 there was several discussions and a first approval, if possible i would not change again heavily the patch structure for a bug that seemss already been fixed.

Quoted 7 lines

So i fixed all the possible points of this thread and organized next patch as

1/4 dmaengine: fsl-edma: extract common fsl-edma code (no changes .. 2/4 dmaengine: fsl-edma: add edma version and configurable registers 3/4 dmaengine: fsl-edma: fix macros
4/4 dmaengine: fsl-edma: add ColdFire mcf5441x edma support

That seems sensible. One minor nit in Kconfig still:

drivers/dma/Kconfig +3 -0

@@ -320,6 +320,17 @@ config LPC18XX_DMAMUX
       Enable support for DMA on NXP LPC18xx/43xx platforms
       with PL080 and multiplexed DMA request lines.
 
+config MCF_EDMA
+    tristate "Freescale eDMA engine support, ColdFire mcf5441x SoCs"
+    depends on M5441x
 

Can you add " || COMPILE_TEST" here, this helps for automated testing.

--
Stefan

Quoted 26 lines

Let me know if you have any other point or if can proceed.

Best regards,
Angelo Dureghello

Quoted 20 lines

--
Stefan

Quoted 13 lines

Best regards,
Krzysztof

Quoted 9 lines

If possible I would prefer if you start with cleanup/conversions, then split-up and finally add functionality.

So ideally:
1. Use macros for preprocessor defines (where you move to BIT/GENMASK)
2. Split
3. Add EDMA macros etc.
4. Add ColdFire mcf5441x edma support

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