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