[PATCH 2/5] spi: pl022: use generic DMA slave configuration if possible
From: arnd@arndb.de (Arnd Bergmann)
Date: 2013-01-28 21:58:17
Also in:
linux-devicetree, linux-spi
Subsystem:
arm primecell ssp pl022 spi driver, open firmware and flattened device tree bindings, spi subsystem, the rest · Maintainers:
Linus Walleij, Rob Herring, Krzysztof Kozlowski, Conor Dooley, Mark Brown, Linus Torvalds
Possibly related (same subject, not in this thread)
- 2013-02-08 · Re: [PATCH 2/5] spi: pl022: use generic DMA slave configuration if possible · Linus Walleij <hidden>
- 2013-02-08 · Re: [PATCH 2/5] spi: pl022: use generic DMA slave configuration if possible · Arnd Bergmann <arnd@arndb.de>
- 2013-02-08 · Re: [PATCH 2/5] spi: pl022: use generic DMA slave configuration if possible · Russell King - ARM Linux <hidden>
- 2013-02-08 · Re: [PATCH 2/5] spi: pl022: use generic DMA slave configuration if possible · Russell King - ARM Linux <hidden>
- 2013-02-07 · Re: [PATCH 2/5] spi: pl022: use generic DMA slave configuration if possible · Arnd Bergmann <hidden>
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: Arnd Bergmann <arnd@arndb.de> Cc: Grant Likely <redacted> Cc: Mark Brown <redacted> Cc: spi-devel-general at lists.sourceforge.net Cc: Viresh Kumar <viresh.kumar@linaro.org> Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Cc: Vinod Koul <redacted> Cc: devicetree-discuss at lists.ozlabs.org Cc: linux-arm-kernel at lists.infradead.org --- .../devicetree/bindings/spi/spi_pl022.txt | 36 ++++++++++++++++++ drivers/spi/spi-pl022.c | 43 +++++++++++++++++++++- 2 files changed, 77 insertions(+), 2 deletions(-)
diff --git a/Documentation/devicetree/bindings/spi/spi_pl022.txt b/Documentation/devicetree/bindings/spi/spi_pl022.txt
index f158fd3..22ed679 100644
--- a/Documentation/devicetree/bindings/spi/spi_pl022.txt
+++ b/Documentation/devicetree/bindings/spi/spi_pl022.txt@@ -16,6 +16,11 @@ Optional properties: device will be suspended immediately - pl022,rt : indicates the controller should run the message pump with realtime 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
@@ -32,3 +37,34 @@ contain the following properties. - pl022,wait-state : Microwire interface: Wait state - pl022,duplex : Microwire interface: Full/Half duplex + +Example: + + spi at 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 at 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>; + }; + }; +
diff --git a/drivers/spi/spi-pl022.c b/drivers/spi/spi-pl022.c
index b0fe393..371cc66f 100644
--- a/drivers/spi/spi-pl022.c
+++ b/drivers/spi/spi-pl022.c@@ -1139,6 +1139,35 @@ err_no_rxchan: 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) { struct dma_chan *rxchan = pl022->dma_rx_channel;
@@ -1167,6 +1196,11 @@ static inline int configure_dma(struct pl022 *pl022) return -ENODEV; } +static inline int pl022_dma_autoprobe(struct pl022 *pl022) +{ + return 0; +} + static inline int pl022_dma_probe(struct pl022 *pl022) { return 0;
@@ -2226,8 +2260,13 @@ static int pl022_probe(struct amba_device *adev, const struct amba_id *id) goto err_no_irq; } - /* Get DMA channels */ - if (platform_info->enable_dma) { + /* Get DMA channels, try autoconfiguration first */ + 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); if (status != 0) platform_info->enable_dma = 0;
--
1.8.0