Commit dc715452 authored by Arnd Bergmann's avatar Arnd Bergmann
Browse files

spi: pl022: use generic DMA slave configuration if possible 



With the new OF DMA binding, it is possible to completely avoid the
need for platform_data for configuring a DMA channel. In cases where the
platform has already been converted, calling dma_request_slave_channel
should get all the necessary information from the device tree.

Like the patch that converts the dw_dma controller, this is completely
untested and is looking for someone to try it out.

Signed-off-by: default avatarArnd Bergmann <arnd@arndb.de>
Acked-by: default avatarGrant Likely <grant.likely@secretlab.ca>
Acked-by: default avatarMark Brown <broonie@opensource.wolfsonmicro.com>
Acked-by: default avatarLinus Walleij <linus.walleij@linaro.org>
Cc: spi-devel-general@lists.sourceforge.net
Cc: Viresh Kumar <viresh.kumar@linaro.org>
Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: Vinod Koul <vinod.koul@linux.intel.com>
Cc: devicetree-discuss@lists.ozlabs.org
Cc: linux-arm-kernel@lists.infradead.org
parent f6161aa1

Documentation/devicetree/bindings/spi/spi_pl022.txt

+36 −0
Original line number Original line Diff line number Diff line
@@ -16,6 +16,11 @@ Optional properties: 
                            device will be suspended immediately

                            device will be suspended immediately

- pl022,rt : indicates the controller should run the message pump with realtime

- pl022,rt : indicates the controller should run the message pump with realtime

             priority to minimise the transfer latency on the bus (boolean)

             priority to minimise the transfer latency on the bus (boolean)

- dmas : Two or more DMA channel specifiers following the convention outlined

         in bindings/dma/dma.txt

- dma-names: Names for the dma channels, if present. There must be at

	     least one channel named "tx" for transmit and named "rx" for

             receive.









SPI slave nodes must be children of the SPI master node and can

SPI slave nodes must be children of the SPI master node and can
@@ -32,3 +37,34 @@ contain the following properties. 
- pl022,wait-state : Microwire interface: Wait state

- pl022,wait-state : Microwire interface: Wait state

- pl022,duplex : Microwire interface: Full/Half duplex

- pl022,duplex : Microwire interface: Full/Half duplex







Example:



	spi@e0100000 {

		compatible = "arm,pl022", "arm,primecell";

		reg = <0xe0100000 0x1000>;

		#address-cells = <1>;

		#size-cells = <0>;

		interrupts = <0 31 0x4>;

		dmas = <&dma-controller 23 1>,

			<&dma-controller 24 0>;

		dma-names = "rx", "tx";



		m25p80@1 {

			compatible = "st,m25p80";

			reg = <1>;

			spi-max-frequency = <12000000>;

			spi-cpol;

			spi-cpha;

			pl022,hierarchy = <0>;

			pl022,interface = <0>;

			pl022,slave-tx-disable;

			pl022,com-mode = <0x2>;

			pl022,rx-level-trig = <0>;

			pl022,tx-level-trig = <0>;

			pl022,ctrl-len = <0x11>;

			pl022,wait-state = <0>;

			pl022,duplex = <0>;

		};

	};

drivers/spi/spi-pl022.c

+41 −2
Original line number Original line Diff line number Diff line
@@ -1139,6 +1139,35 @@ err_no_rxchan: 
	return -ENODEV;

	return -ENODEV;

}

}





static int pl022_dma_autoprobe(struct pl022 *pl022)

{

	struct device *dev = &pl022->adev->dev;



	/* automatically configure DMA channels from platform, normally using DT */

	pl022->dma_rx_channel = dma_request_slave_channel(dev, "rx");

	if (!pl022->dma_rx_channel)

		goto err_no_rxchan;



	pl022->dma_tx_channel = dma_request_slave_channel(dev, "tx");

	if (!pl022->dma_tx_channel)

		goto err_no_txchan;



	pl022->dummypage = kmalloc(PAGE_SIZE, GFP_KERNEL);

	if (!pl022->dummypage)

		goto err_no_dummypage;



	return 0;



err_no_dummypage:

	dma_release_channel(pl022->dma_tx_channel);

	pl022->dma_tx_channel = NULL;

err_no_txchan:

	dma_release_channel(pl022->dma_rx_channel);

	pl022->dma_rx_channel = NULL;

err_no_rxchan:

	return -ENODEV;

}

		

static void terminate_dma(struct pl022 *pl022)

static void terminate_dma(struct pl022 *pl022)

{

{

	struct dma_chan *rxchan = pl022->dma_rx_channel;

	struct dma_chan *rxchan = pl022->dma_rx_channel;
@@ -1167,6 +1196,11 @@ static inline int configure_dma(struct pl022 *pl022) 
	return -ENODEV;

	return -ENODEV;

}

}





static inline int pl022_dma_autoprobe(struct pl022 *pl022)

{

	return 0;

}



static inline int pl022_dma_probe(struct pl022 *pl022)

static inline int pl022_dma_probe(struct pl022 *pl022)

{

{

	return 0;

	return 0;
@@ -2226,8 +2260,13 @@ static int pl022_probe(struct amba_device *adev, const struct amba_id *id) 
		goto err_no_irq;

		goto err_no_irq;

	}

	}





	/* Get DMA channels */

	/* Get DMA channels, try autoconfiguration first */

	if (platform_info->enable_dma) {

	status = pl022_dma_autoprobe(pl022);



	/* If that failed, use channels from platform_info */

	if (status == 0)

		platform_info->enable_dma = 1;

	else if (platform_info->enable_dma) {

		status = pl022_dma_probe(pl022);

		status = pl022_dma_probe(pl022);

		if (status != 0)

		if (status != 0)

			platform_info->enable_dma = 0;

			platform_info->enable_dma = 0;

CRA Git | Maintained and supported by SUSTech CRA and CCSE