linux-kernel - [PATCH v4 05/11] dmaengine: Introduce DMA-device device

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Message-ID: <20200528222401.26941-6-Sergey.Semin@baikalelectronics.ru>
Date:   Fri, 29 May 2020 01:23:55 +0300
From:   Serge Semin <Sergey.Semin@...kalelectronics.ru>
To:     Vinod Koul <vkoul@...nel.org>, Viresh Kumar <vireshk@...nel.org>,
        Dan Williams <dan.j.williams@...el.com>
CC:     Serge Semin <Sergey.Semin@...kalelectronics.ru>,
        Serge Semin <fancer.lancer@...il.com>,
        Alexey Malahov <Alexey.Malahov@...kalelectronics.ru>,
        Thomas Bogendoerfer <tsbogend@...ha.franken.de>,
        Arnd Bergmann <arnd@...db.de>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Rob Herring <robh+dt@...nel.org>, <linux-mips@...r.kernel.org>,
        <devicetree@...r.kernel.org>, <dmaengine@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>
Subject: [PATCH v4 05/11] dmaengine: Introduce DMA-device device_caps callback

There are DMA devices (like ours version of Synopsys DW DMAC) which have
DMA capabilities non-uniformly redistributed amongst the device channels.
In order to provide a way of exposing the channel-specific parameters to
the DMA engine consumers, we introduce a new DMA-device callback. In case
if provided it gets called from the dma_get_slave_caps() method and is
able to override the generic DMA-device capabilities.

Signed-off-by: Serge Semin <Sergey.Semin@...kalelectronics.ru>
Cc: Alexey Malahov <Alexey.Malahov@...kalelectronics.ru>
Cc: Thomas Bogendoerfer <tsbogend@...ha.franken.de>
Cc: Arnd Bergmann <arnd@...db.de>
Cc: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
Cc: Rob Herring <robh+dt@...nel.org>
Cc: linux-mips@...r.kernel.org
Cc: devicetree@...r.kernel.org

---

Changelog v3:
- This is a new patch created as a result of the discussion with Vinod and
  Andy in the framework of DW DMA burst and LLP capabilities.
---
 drivers/dma/dmaengine.c   | 3 +++
 include/linux/dmaengine.h | 2 ++
 2 files changed, 5 insertions(+)

diff --git a/drivers/dma/dmaengine.c b/drivers/dma/dmaengine.c
index ad56ad58932c..edbb11d56cde 100644
--- a/drivers/dma/dmaengine.c
+++ b/drivers/dma/dmaengine.c
@@ -599,6 +599,9 @@ int dma_get_slave_caps(struct dma_chan *chan, struct dma_slave_caps *caps)
 	caps->cmd_resume = !!device->device_resume;
 	caps->cmd_terminate = !!device->device_terminate_all;
 
+	if (device->device_caps)
+		device->device_caps(chan, caps);
+
 	return 0;
 }
 EXPORT_SYMBOL_GPL(dma_get_slave_caps);
diff --git a/include/linux/dmaengine.h b/include/linux/dmaengine.h
index a7e4d8dfdd19..b303e59929e5 100644
--- a/include/linux/dmaengine.h
+++ b/include/linux/dmaengine.h
@@ -899,6 +899,8 @@ struct dma_device {
 		struct dma_chan *chan, dma_addr_t dst, u64 data,
 		unsigned long flags);
 
+	void (*device_caps)(struct dma_chan *chan,
+			    struct dma_slave_caps *caps);
 	int (*device_config)(struct dma_chan *chan,
 			     struct dma_slave_config *config);
 	int (*device_pause)(struct dma_chan *chan);
-- 
2.26.2