[PATCH RFC 1/2] ARM: shmobile: lager: Use DMA bounce for PCI devices

[Valentine Barshak <valentine.barshak@cogentembedded.com>]

Since R-Car Gen2 PCI controller does not support
more than 2GB memory window limit DMA mask for
PCI devices to 31 bits and enable DMA bounce.

Signed-off-by: Valentine Barshak <valentine.barshak@cogentembedded.com>
---
 arch/arm/mach-shmobile/Kconfig       |  2 ++
 arch/arm/mach-shmobile/board-lager.c | 38 ++++++++++++++++++++++++++++++++++++
 2 files changed, 40 insertions(+)

diff --git a/arch/arm/mach-shmobile/Kconfig b/arch/arm/mach-shmobile/Kconfig
index 8011329..bfd8757 100644
--- a/arch/arm/mach-shmobile/Kconfig
+++ b/arch/arm/mach-shmobile/Kconfig
@@ -126,6 +126,7 @@ config ARCH_R8A7790
 	select MIGHT_HAVE_PCI
 	select SH_CLK_CPG
 	select RENESAS_IRQC
+	select DMABOUNCE if PCI_RCAR_GEN2
 
 config ARCH_R8A7791
 	bool "R-Car M2 (R8A77910)"
@@ -135,6 +136,7 @@ config ARCH_R8A7791
 	select MIGHT_HAVE_PCI
 	select SH_CLK_CPG
 	select RENESAS_IRQC
+	select DMABOUNCE if PCI_RCAR_GEN2
 
 config ARCH_EMEV2
 	bool "Emma Mobile EV2"
diff --git a/arch/arm/mach-shmobile/board-lager.c b/arch/arm/mach-shmobile/board-lager.c
index 972633e..2044a23 100644
--- a/arch/arm/mach-shmobile/board-lager.c
+++ b/arch/arm/mach-shmobile/board-lager.c
@@ -26,6 +26,7 @@
 #include <linux/leds.h>
 #include <linux/mmc/host.h>
 #include <linux/mmc/sh_mmcif.h>
+#include <linux/pci.h>
 #include <linux/pinctrl/machine.h>
 #include <linux/platform_data/camera-rcar.h>
 #include <linux/platform_data/gpio-rcar.h>
@@ -546,9 +547,43 @@ static const struct resource usbhs_phy_resources[] __initconst = {
 	DEFINE_RES_MEM(0xe6590100, 0x100),
 };
 
+#if IS_ENABLED(CONFIG_DMABOUNCE)
+static int lager_needs_bounce(struct device *dev,
+			      dma_addr_t dma_addr, size_t size)
+{
+	return 0;
+}
+
+static int lager_platform_notify(struct device *dev)
+{
+	if (dev_is_pci(dev)) {
+		*dev->dma_mask =  DMA_BIT_MASK(31);
+		dev->coherent_dma_mask = DMA_BIT_MASK(31);
+		dmabounce_register_dev(dev, SZ_2K, SZ_4K,
+				       lager_needs_bounce);
+	}
+
+	return 0;
+}
+
+static int lager_platform_notify_remove(struct device *dev)
+{
+	if (dev_is_pci(dev))
+		dmabounce_unregister_dev(dev);
+
+	return 0;
+}
+#endif
+
 /* Add all available USB devices */
 static void __init lager_add_usb_devices(void)
 {
+
+#if IS_ENABLED(CONFIG_DMABOUNCE)
+	platform_notify = lager_platform_notify;
+	platform_notify_remove = lager_platform_notify_remove;
+#endif
+
 	platform_device_register_resndata(&platform_bus, "usb_phy_rcar_gen2",
 					  -1, usbhs_phy_resources,
 					  ARRAY_SIZE(usbhs_phy_resources),
@@ -707,4 +742,7 @@ DT_MACHINE_START(LAGER_DT, "lager")
 	.init_machine	= lager_init,
 	.init_late	= shmobile_init_late,
 	.dt_compat	= lager_boards_compat_dt,
+#if IS_ENABLED(CONFIG_ZONE_DMA)
+	.dma_zone_size	= SZ_1G
+#endif
 MACHINE_END
-- 
1.8.3.1