From 3f4232ee8b53cf2266d227af299aa511d2d91d11 Mon Sep 17 00:00:00 2001 From: Mika Westerberg Date: Mon, 14 Sep 2015 17:37:36 +0300 Subject: [PATCH] acpi-dma: Add support for "dma-names" device property The current implementation hard codes the two supported channels so that "tx" is always 0 and "rx" is always 1. This is because there has been no suitable way in ACPI to name resources. With _DSD device properties we can finally do this: Device (SPI1) { Name (_CRS, ResourceTemplate () { ... FixedDMA (0x0000, 0x0000, Width32bit) FixedDMA (0x0001, 0x0001, Width32bit) }) Name (_DSD, Package () { ToUUID("daffd814-6eba-4d8c-8a91-bc9bbf4aa301"), Package () { Package () {"dma-names", Package () {"tx", "rx"}} }, }) } The names "tx" and "rx" now provide index of the FixedDMA resource in question. Modify acpi_dma_request_slave_chan_by_name() so that it looks for "dma-names" property first and only then fall back using hardcoded indices. The DT "dma-names" binding that we reuse for ACPI is documented in Documentation/devicetree/bindings/dma/dma.txt. Signed-off-by: Mika Westerberg Acked-by: Andy Shevchenko Acked-by: Vinod Koul Signed-off-by: Rafael J. Wysocki --- drivers/dma/acpi-dma.c | 25 +++++++++++++++++-------- 1 file changed, 17 insertions(+), 8 deletions(-) diff --git a/drivers/dma/acpi-dma.c b/drivers/dma/acpi-dma.c index 5a635646e05c..981a38fc4cb8 100644 --- a/drivers/dma/acpi-dma.c +++ b/drivers/dma/acpi-dma.c @@ -21,6 +21,7 @@ #include #include #include +#include static LIST_HEAD(acpi_dma_list); static DEFINE_MUTEX(acpi_dma_lock); @@ -413,21 +414,29 @@ EXPORT_SYMBOL_GPL(acpi_dma_request_slave_chan_by_index); * translate the names "tx" and "rx" here based on the most common case where * the first FixedDMA descriptor is TX and second is RX. * + * If the device has "dma-names" property the FixedDMA descriptor indices + * are retrieved based on those. Otherwise the function falls back using + * hardcoded indices. + * * Return: * Pointer to appropriate dma channel on success or an error pointer. */ struct dma_chan *acpi_dma_request_slave_chan_by_name(struct device *dev, const char *name) { - size_t index; - - if (!strcmp(name, "tx")) - index = 0; - else if (!strcmp(name, "rx")) - index = 1; - else - return ERR_PTR(-ENODEV); + int index; + + index = device_property_match_string(dev, "dma-names", name); + if (index < 0) { + if (!strcmp(name, "tx")) + index = 0; + else if (!strcmp(name, "rx")) + index = 1; + else + return ERR_PTR(-ENODEV); + } + dev_dbg(dev, "found DMA channel \"%s\" at index %d\n", name, index); return acpi_dma_request_slave_chan_by_index(dev, index); } EXPORT_SYMBOL_GPL(acpi_dma_request_slave_chan_by_name); -- 2.30.2