[PATCH 2/5] spi: pl022: use generic DMA slave configuration if possible

Arnd Bergmann
2013-01-28T21:58:17Z

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 <grant.likely@secretlab.ca>
Cc: Mark Brown <broonie@opensource.wolfsonmicro.com>
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 <vinod.koul@linux.intel.com>
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