So far, whether device DMA is coherent was a one-time global decision. This is insufficient, because some platforms:
- are cache coherent, while the architecture isn't in general, e.g. ARM with CONFIG_MMU=y assumes non-coherent DMA, but LS1046A is coherent - have a mix of devices that snoop caches and devices that don't (StarFive JH7100). To enable dev_dma_(map|unmap)_single to take the correct device-specific action with regards to cache maintenance, provide dev_is_dma_coherent() with semantics similar to what Linux provides. This admittedly looks a bit ugly, but we will refrain from making dma_coherent defined independent of ifdef CONFIG_ARCH_HAS_NONCOHERENT_DMA: On platforms that are cache-coherent, we will want dev->dma_coherent to be true. Yet not all code allocating devices uses dev_alloc(), so adding a global toggle is a bit too much refactoring effort for now. Signed-off-by: Ahmad Fatoum <[email protected]> --- commands/devinfo.c | 5 +++++ drivers/of/platform.c | 3 +++ include/driver.h | 28 ++++++++++++++++++++++++++++ 3 files changed, 36 insertions(+) diff --git a/commands/devinfo.c b/commands/devinfo.c index 2487786c7101..be28d02028c3 100644 --- a/commands/devinfo.c +++ b/commands/devinfo.c @@ -50,6 +50,7 @@ static int do_devinfo(int argc, char *argv[]) struct param_d *param; int i; int first; + int coherent; struct resource *res; if (argc == 1) { @@ -82,6 +83,10 @@ static int do_devinfo(int argc, char *argv[]) if (dev->bus) printf("Bus: %s\n", dev->bus->name); + coherent = dev_is_dma_coherent(dev); + if (coherent >= 0) + printf("DMA Coherent: %s\n", coherent ? "true" : "false"); + if (dev->info) dev->info(dev); diff --git a/drivers/of/platform.c b/drivers/of/platform.c index 0982873446a6..1bd5d41ba226 100644 --- a/drivers/of/platform.c +++ b/drivers/of/platform.c @@ -128,6 +128,9 @@ static void of_dma_configure(struct device *dev, struct device_node *np) } dev->dma_offset = offset; +#ifdef CONFIG_OF_DMA_COHERENCY + dev->dma_coherent = of_dma_is_coherent(np); +#endif } /** diff --git a/include/driver.h b/include/driver.h index 7e25c060280b..f6301d954bb5 100644 --- a/include/driver.h +++ b/include/driver.h @@ -8,6 +8,7 @@ #include <linux/list.h> #include <linux/ioport.h> +#include <linux/bitops.h> #include <of.h> #include <filetype.h> @@ -43,6 +44,13 @@ struct device { * something like eth0 or nor0. */ int id; + /*! This particular device is dma coherent, even if the + * architecture supports non-coherent devices. + */ +#ifdef CONFIG_OF_DMA_COHERENCY + bool dma_coherent:1; +#endif + struct resource *resource; int num_resources; @@ -652,6 +660,26 @@ static inline struct device_node *dev_of_node(struct device *dev) return IS_ENABLED(CONFIG_OFDEVICE) ? dev->of_node : NULL; } +#ifdef CONFIG_OF_DMA_COHERENCY +static inline int __dev_is_dma_coherent(struct device *dev) +{ + return dev->dma_coherent; +} +#else +static inline bool __dev_is_dma_coherent(struct device *dev) +{ + return IS_ENABLED(CONFIG_OF_DMA_DEFAULT_COHERENT); +} +#endif + +static inline int dev_is_dma_coherent(struct device *dev) +{ + if (!dev_of_node(dev)) + return -EINVAL; + + return __dev_is_dma_coherent(dev); +} + static inline void *dev_get_priv(const struct device *dev) { return dev->priv; -- 2.30.2
