[PATCH] dma: sun4i: expose block size and wait cycle configuration to DMA users

Boris Brezillon
2016-03-07T10:25:53Z

Some drivers might need to tweak the block size and wait cycles values
to get better performances.
Create and export the sun4i_dma_set_chan_config() to do that.

Signed-off-by: Boris Brezillon <boris.brezillon@free-electrons.com>
---
drivers/dma/sun4i-dma.c | 44 ++++++++++++++++++++++++++++++-------------
include/linux/dma/sun4i-dma.h | 38 +++++++++++++++++++++++++++++++++++++
2 files changed, 69 insertions(+), 13 deletions(-)
create mode 100644 include/linux/dma/sun4i-dma.h

diff --git a/drivers/dma/sun4i-dma.c b/drivers/dma/sun4i-dma.c
index 1661d518..e48f537 100644
--- a/drivers/dma/sun4i-dma.c
+++ b/drivers/dma/sun4i-dma.c
@@ -12,6 +12,7 @@
#include <linux/bitops.h>
#include <linux/clk.h>
#include <linux/dmaengine.h>
+#include <linux/dma/sun4i-dma.h>
#include <linux/dmapool.h>
#include <linux/interrupt.h>
#include <linux/module.h>
@@ -138,6 +139,7 @@ struct sun4i_dma_pchan {
struct sun4i_dma_vchan {
struct virt_dma_chan vc;
struct dma_slave_config cfg;
+ struct sun4i_dma_chan_config scfg;
struct sun4i_dma_pchan *pchan;
struct sun4i_dma_promise *processing;
struct sun4i_dma_contract *contract;
@@ -779,7 +781,7 @@ sun4i_dma_prep_slave_sg(struct dma_chan *chan, struct scatterlist *sgl,
u8 ram_type, io_mode, linear_mode;
struct scatterlist *sg;
dma_addr_t srcaddr, dstaddr;
- u32 endpoints, para;
+ u32 endpoints;
int i;

if (!sgl)
@@ -825,17 +827,6 @@ sun4i_dma_prep_slave_sg(struct dma_chan *chan, struct scatterlist *sgl,
dstaddr = sg_dma_address(sg);
}

- /*
- * These are the magic DMA engine timings that keep SPI going.
- * I haven't seen any interface on DMAEngine to configure
- * timings, and so far they seem to work for everything we
- * support, so I've kept them here. I don't know if other
- * devices need different timings because, as usual, we only
- * have the "para" bitfield meanings, but no comment on what
- * the values should be when doing a certain operation :|
- */
- para = SUN4I_DDMA_MAGIC_SPI_PARAMETERS;
-
/* And make a suitable promise */
if (vchan->is_dedicated)
promise = generate_ddma_promise(chan, srcaddr, dstaddr,
@@ -850,7 +841,7 @@ sun4i_dma_prep_slave_sg(struct dma_chan *chan, struct scatterlist *sgl,
return NULL; /* TODO: should we free everything? */

promise->cfg |= endpoints;
- promise->para = para;
+ promise->para = vchan->scfg.para;

/* Then add it to the contract */
list_add_tail(&promise->list, &contract->demands);
@@ -908,6 +899,21 @@ static int sun4i_dma_config(struct dma_chan *chan,
return 0;
}

+int sun4i_dma_set_chan_config(struct dma_chan *dchan,
+ const struct sun4i_dma_chan_config *cfg)
+{
+ struct sun4i_dma_vchan *vchan = to_sun4i_dma_vchan(dchan);
+
+ if (!vchan->is_dedicated)
+ return -ENOTSUPP;
+
+ /* TODO: control cfg value */
+ vchan->scfg = *cfg;
+
+ return 0;
+}
+EXPORT_SYMBOL_GPL(sun4i_dma_set_chan_config);
+
static struct dma_chan *sun4i_dma_of_xlate(struct of_phandle_args *dma_spec,
struct of_dma *ofdma)
{
@@ -1206,6 +1212,18 @@ static int sun4i_dma_probe(struct platform_device *pdev)
spin_lock_init(&vchan->vc.lock);
vchan->vc.desc_free = sun4i_dma_free_contract;
vchan_init(&vchan->vc, &priv->slave);
+
+ /*
+ * These are the magic DMA engine timings that keep SPI going.
+ * I haven't seen any interface on DMAEngine to configure
+ * timings, and so far they seem to work for everything we
+ * support, so I've kept them here. I don't know if other
+ * devices need different timings because, as usual, we only
+ * have the "para" bitfield meanings, but no comment on what
+ * the values should be when doing a certain operation :|
+ */
+ vchan->scfg.para = SUN4I_DDMA_MAGIC_SPI_PARAMETERS;
+
}

ret = clk_prepare_enable(priv->clk);
diff --git a/include/linux/dma/sun4i-dma.h b/include/linux/dma/sun4i-dma.h
new file mode 100644
index 0000000..f643539
--- /dev/null
+++ b/include/linux/dma/sun4i-dma.h
@@ -0,0 +1,38 @@
+/*
+ * Sun4i DMA Engine drivers support header file
+ *
+ * Copyright (C) 2016 Free Electrons. All rights reserved.
+ *
+ * This is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ */
+
+#ifndef _SUN4I_DMA_H
+#define _SUN4I_DMA_H
+
+#include <linux/dma-mapping.h>
+#include <linux/dmaengine.h>
+
+/* Dedicated DMA parameter register layout */
+#define SUN4I_DDMA_PARA_DST_DATA_BLK_SIZE(n) (((n) - 1) << 24)
+#define SUN4I_DDMA_PARA_DST_WAIT_CYCLES(n) (((n) - 1) << 16)
+#define SUN4I_DDMA_PARA_SRC_DATA_BLK_SIZE(n) (((n) - 1) << 8)
+#define SUN4I_DDMA_PARA_SRC_WAIT_CYCLES(n) (((n) - 1) << 0)
+
+/**
+ * struct sun4i_dma_chan_config - DMA channel config
+ *
+ * @para: contains information about block size and time before checking
+ * DRQ line. This is device specific and only applicable to dedicated
+ * DMA channels
+ */
+struct sun4i_dma_chan_config {
+ u32 para;
+};
+
+int sun4i_dma_set_chan_config(struct dma_chan *dchan,
+ const struct sun4i_dma_chan_config *cfg);
+
+#endif /* _SUN4I_DMA_H */
--
2.1.4