[PATCH wireless-drivers-next] bcma: get SoC device struct & copy its DMA params to the subdevices

["Rafał Miłecki" <zajec5@gmail.com>]

From: Rafał Miłecki <rafal@milecki.pl>

For bus devices to be fully usable it's required to set their DMA
parameters.

For years it has been missing and remained unnoticed because of
mips_dma_alloc_coherent() silently handling the empty coherent_dma_mask.
Kernel 4.19 came with a lot of DMA changes and caused a regression on
the bcm47xx. Starting with the commit f8c55dc6e828 ("MIPS: use generic
dma noncoherent ops for simple noncoherent platforms") DMA coherent
allocations just fail. Example:
[    1.114914] bgmac_bcma bcma0:2: Allocation of TX ring 0x200 failed
[    1.121215] bgmac_bcma bcma0:2: Unable to alloc memory for DMA
[    1.127626] bgmac_bcma: probe of bcma0:2 failed with error -12
[    1.133838] bgmac_bcma: Broadcom 47xx GBit MAC driver loaded

This change fixes above regression in addition to the MIPS bcm47xx
commit 321c46b91550 ("MIPS: BCM47XX: Setup struct device for the SoC").

It also fixes another *old* GPIO regression caused by a parent pointing
to the NULL:
[    0.157054] missing gpiochip .dev parent pointer
[    0.157287] bcma: bus0: Error registering GPIO driver: -22
introduced by the commit 74f4e0cc6108 ("bcma: switch GPIO portions to
use GPIOLIB_IRQCHIP").

Fixes: f8c55dc6e828 ("MIPS: use generic dma noncoherent ops for simple noncoherent platforms")
Fixes: 74f4e0cc6108 ("bcma: switch GPIO portions to use GPIOLIB_IRQCHIP")
Cc: linux-mips@linux-mips.org
Cc: Christoph Hellwig <hch@lst.de>
Cc: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Rafał Miłecki <rafal@milecki.pl>
---
While this patch is a regression fix, it depends on a change present in
the wireless-drivers-next.git:
bcma: keep a direct pointer to the struct device

That's why I suggest pushing it into the wireless-drivers-next.git and I
can take care of picking it for the stable@kernel.org later.

Another option would be cherry-picking commit 5a1c18b761dd ("bcma: keep
a direct pointer to the struct device") to the wireless-drivers.git but
I don't think it's a common practice.
---
 drivers/bcma/host_soc.c       | 2 ++
 drivers/bcma/main.c           | 6 +++++-
 include/linux/bcma/bcma_soc.h | 1 +
 3 files changed, 8 insertions(+), 1 deletion(-)

diff --git a/drivers/bcma/host_soc.c b/drivers/bcma/host_soc.c
index c8073b509a2b..1fdfb704f22d 100644
--- a/drivers/bcma/host_soc.c
+++ b/drivers/bcma/host_soc.c
@@ -191,6 +191,8 @@ int __init bcma_host_soc_init(struct bcma_soc *soc)
 	struct bcma_bus *bus = &soc->bus;
 	int err;
 
+	bus->dev = soc->dev;
+
 	/* Scan bus and initialize it */
 	err = bcma_bus_early_register(bus);
 	if (err)
diff --git a/drivers/bcma/main.c b/drivers/bcma/main.c
index 6535614a7dc1..433ca5e2ed2c 100644
--- a/drivers/bcma/main.c
+++ b/drivers/bcma/main.c
@@ -236,12 +236,16 @@ EXPORT_SYMBOL(bcma_core_irq);
 
 void bcma_prepare_core(struct bcma_bus *bus, struct bcma_device *core)
 {
+	struct device *dev = &core->dev;
+
 	core->dev.release = bcma_release_core_dev;
 	core->dev.bus = &bcma_bus_type;
 	dev_set_name(&core->dev, "bcma%d:%d", bus->num, core->core_index);
 	core->dev.parent = bus->dev;
-	if (bus->dev)
+	if (bus->dev) {
 		bcma_of_fill_device(bus->dev, core);
+		dma_coerce_mask_and_coherent(dev, bus->dev->coherent_dma_mask);
+	}
 
 	switch (bus->hosttype) {
 	case BCMA_HOSTTYPE_PCI:
diff --git a/include/linux/bcma/bcma_soc.h b/include/linux/bcma/bcma_soc.h
index 7cca5f859a90..f3c43519baa7 100644
--- a/include/linux/bcma/bcma_soc.h
+++ b/include/linux/bcma/bcma_soc.h
@@ -6,6 +6,7 @@
 
 struct bcma_soc {
 	struct bcma_bus bus;
+	struct device *dev;
 };
 
 int __init bcma_host_soc_register(struct bcma_soc *soc);
-- 
2.20.1