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Message-Id: <1372667978-4718-2-git-send-email-richard.genoud@gmail.com>
Date: Mon, 1 Jul 2013 10:39:26 +0200
From: Richard Genoud <richard.genoud@...il.com>
To: devicetree-discuss@...ts.ozlabs.org
Cc: linux-arm-kernel@...ts.infradead.org,
Nicolas Ferre <nicolas.ferre@...el.com>,
Uwe Kleine-König
<u.kleine-koenig@...gutronix.de>, linux-kernel@...r.kernel.org,
Richard Genoud <richard.genoud@...il.com>
Subject: [RFC PATCH 01/13] misc: atmel_ssc: add device tree DMA support
The ssc device has to fill the at_dma_slave structure with the
device tree informations.
Doing a of_dma_request_slave_channel()+dma_release_channel() for that
seems wrong (or at least not very clean).
Signed-off-by: Richard Genoud <richard.genoud@...il.com>
---
drivers/misc/atmel-ssc.c | 56 +++++++++++++++++++++++++++++++
include/linux/atmel-ssc.h | 2 ++
include/linux/platform_data/dma-atmel.h | 2 ++
3 files changed, 60 insertions(+)
diff --git a/drivers/misc/atmel-ssc.c b/drivers/misc/atmel-ssc.c
index f7b90661..3afbd82 100644
--- a/drivers/misc/atmel-ssc.c
+++ b/drivers/misc/atmel-ssc.c
@@ -19,7 +19,9 @@
#include <linux/module.h>
#include <linux/of.h>
+#include <linux/of_dma.h>
#include <linux/pinctrl/consumer.h>
+#include <linux/platform_data/dma-atmel.h>
/* Serialize access to ssc_list and user count */
static DEFINE_SPINLOCK(user_lock);
@@ -127,12 +129,57 @@ static inline const struct atmel_ssc_platform_data * __init
platform_get_device_id(pdev)->driver_data;
}
+static int atmel_ssc_get_dma_data(struct device_node *np,
+ struct at_dma_slave *sdata)
+{
+ struct dma_chan *chan;
+ struct at_dma_slave *rx_data;
+ int err = -1;
+
+ /*
+ * FIXME: this is clearly not the right way to do it.
+ * In order to fill struct at_dma_slave with both rx and tx data,
+ * we request and release both channels.
+ * Et voila ! We've got all the whole structure !
+ * upside: it works(R)
+ * downside: feels wrong, dirty, not optimized...
+ */
+ chan = of_dma_request_slave_channel(np, "tx");
+ if (!chan)
+ return err;
+
+ if (chan->private)
+ memcpy(sdata, chan->private, sizeof(*sdata));
+ else
+ goto out;
+
+ dma_release_channel(chan);
+
+ chan = of_dma_request_slave_channel(np, "rx");
+ if (!chan)
+ goto out;
+
+ if (chan->private) {
+ rx_data = chan->private;
+ sdata->cfg &= ~(ATC_SRC_PER_MSB(0xff) | ATC_SRC_PER(0xff));
+ sdata->cfg |= ATC_GET_SRC_ID(rx_data->cfg);
+ err = 0;
+ }
+
+out:
+ if (chan)
+ dma_release_channel(chan);
+
+ return err;
+}
+
static int ssc_probe(struct platform_device *pdev)
{
struct resource *regs;
struct ssc_device *ssc;
const struct atmel_ssc_platform_data *plat_dat;
struct pinctrl *pinctrl;
+ struct device_node *of = pdev->dev.of_node;
pinctrl = devm_pinctrl_get_select_default(&pdev->dev);
if (IS_ERR(pinctrl)) {
@@ -166,6 +213,15 @@ static int ssc_probe(struct platform_device *pdev)
return -ENXIO;
}
+ /* populate platform_data from device tree */
+ if (ssc->pdata && ssc->pdata->use_dma && of) {
+ if (atmel_ssc_get_dma_data(of, &ssc->pdata->dma_slave)) {
+ dev_err(&pdev->dev, "could not get DMA\n");
+ return -EINVAL;
+ }
+ }
+ ssc->pdev->dev.platform_data = &ssc->pdata->dma_slave;
+
/* disable all interrupts */
clk_prepare_enable(ssc->clk);
ssc_writel(ssc->regs, IDR, -1);
diff --git a/include/linux/atmel-ssc.h b/include/linux/atmel-ssc.h
index deb0ae5..80c83ee 100644
--- a/include/linux/atmel-ssc.h
+++ b/include/linux/atmel-ssc.h
@@ -1,12 +1,14 @@
#ifndef __INCLUDE_ATMEL_SSC_H
#define __INCLUDE_ATMEL_SSC_H
+#include <linux/platform_data/dma-atmel.h>
#include <linux/platform_device.h>
#include <linux/list.h>
#include <linux/io.h>
struct atmel_ssc_platform_data {
int use_dma;
+ struct at_dma_slave dma_slave;
};
struct ssc_device {
diff --git a/include/linux/platform_data/dma-atmel.h b/include/linux/platform_data/dma-atmel.h
index e95f19c..0d8b9d6 100644
--- a/include/linux/platform_data/dma-atmel.h
+++ b/include/linux/platform_data/dma-atmel.h
@@ -44,11 +44,13 @@ struct at_dma_slave {
#define ATC_SRC_H2SEL_SW (0x0 << 9)
#define ATC_SRC_H2SEL_HW (0x1 << 9)
#define ATC_SRC_PER_MSB(h) (ATC_PER_MSB(h) << 10) /* Channel src rq (most significant bits) */
+#define ATC_GET_SRC_ID(h) ((((h) >> 6) & 0x3U) | ((h) & 0xFU)) /* Retrieve channel src id */
#define ATC_DST_REP (0x1 << 12) /* Destination Replay Mod */
#define ATC_DST_H2SEL (0x1 << 13) /* Destination Handshaking Mod */
#define ATC_DST_H2SEL_SW (0x0 << 13)
#define ATC_DST_H2SEL_HW (0x1 << 13)
#define ATC_DST_PER_MSB(h) (ATC_PER_MSB(h) << 14) /* Channel dst rq (most significant bits) */
+#define ATC_GET_DST_ID(h) ((((h) >> 10) & 0x3U) | (((h) >> 4) & 0xFU)) /* Retrieve channel dst id */
#define ATC_SOD (0x1 << 16) /* Stop On Done */
#define ATC_LOCK_IF (0x1 << 20) /* Interface Lock */
#define ATC_LOCK_B (0x1 << 21) /* AHB Bus Lock */
--
1.7.10.4
--
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