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Subject[PATCH V2 mips-fixes] MIPS: BCM47XX: Setup struct device for the SoC
Date
From: Rafał Miłecki <rafal@milecki.pl>

So far we never had any device registered for the SoC. This resulted in
some small issues that we kept ignoring like:
1) Not working GPIOLIB_IRQCHIP (gpiochip_irqchip_add_key() failing)
2) Lack of proper tree in the /sys/devices/
3) mips_dma_alloc_coherent() silently handling empty coherent_dma_mask

Kernel 4.19 came with a lot of DMA changes and caused a regression on
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

The bgmac driver also triggers a WARNING:
[ 0.959486] ------------[ cut here ]------------
[ 0.964387] WARNING: CPU: 0 PID: 1 at ./include/linux/dma-mapping.h:516 bgmac_enet_probe+0x1b4/0x5c4
[ 0.973751] Modules linked in:
[ 0.976913] CPU: 0 PID: 1 Comm: swapper Not tainted 4.19.9 #0
[ 0.982750] Stack : 804a0000 804597c4 00000000 00000000 80458fd8 8381bc2c 838282d4 80481a47
[ 0.991367] 8042e3ec 00000001 804d38f0 00000204 83980000 00000065 8381bbe0 6f55b24f
[ 0.999975] 00000000 00000000 80520000 00002018 00000000 00000075 00000007 00000000
[ 1.008583] 00000000 80480000 000ee811 00000000 00000000 00000000 80432c00 80248db8
[ 1.017196] 00000009 00000204 83980000 803ad7b0 00000000 801feeec 00000000 804d0000
[ 1.025804] ...
[ 1.028325] Call Trace:
[ 1.030875] [<8000aef8>] show_stack+0x58/0x100
[ 1.035513] [<8001f8b4>] __warn+0xe4/0x118
[ 1.039708] [<8001f9a4>] warn_slowpath_null+0x48/0x64
[ 1.044935] [<80248db8>] bgmac_enet_probe+0x1b4/0x5c4
[ 1.050101] [<802498e0>] bgmac_probe+0x558/0x590
[ 1.054906] [<80252fd0>] bcma_device_probe+0x38/0x70
[ 1.060017] [<8020e1e8>] really_probe+0x170/0x2e8
[ 1.064891] [<8020e714>] __driver_attach+0xa4/0xec
[ 1.069784] [<8020c1e0>] bus_for_each_dev+0x58/0xb0
[ 1.074833] [<8020d590>] bus_add_driver+0xf8/0x218
[ 1.079731] [<8020ef24>] driver_register+0xcc/0x11c
[ 1.084804] [<804b54cc>] bgmac_init+0x1c/0x44
[ 1.089258] [<8000121c>] do_one_initcall+0x7c/0x1a0
[ 1.094343] [<804a1d34>] kernel_init_freeable+0x150/0x218
[ 1.099886] [<803a082c>] kernel_init+0x10/0x104
[ 1.104583] [<80005878>] ret_from_kernel_thread+0x14/0x1c
[ 1.110107] ---[ end trace f441c0d873d1fb5b ]---

This patch setups a "struct device" (and passes it to the bcma) which
allows fixing all the mentioned problems. It'll also require a tiny bcma
patch which will follow through the wireless tree & its maintainer.

Fixes: f8c55dc6e828 ("MIPS: use generic dma noncoherent ops for simple noncoherent platforms")
Cc: Christoph Hellwig <hch@lst.de>
Cc: Linus Walleij <linus.walleij@linaro.org>
Cc: linux-wireless@vger.kernel.org
Cc: stable@vger.kernel.org # v4.19+
Signed-off-by: Rafał Miłecki <rafal@milecki.pl>
Acked-by: Hauke Mehrtens <hauke@hauke-m.de>
---
V2: Reorder struct bcma_soc fields (trivial optimization - thanks Hauke)
Add pr_err on error
---
arch/mips/bcm47xx/setup.c | 31 +++++++++++++++++++++++++++++++
include/linux/bcma/bcma_soc.h | 1 +
2 files changed, 32 insertions(+)

diff --git a/arch/mips/bcm47xx/setup.c b/arch/mips/bcm47xx/setup.c
index 6054d49e608e..fe3773539eff 100644
--- a/arch/mips/bcm47xx/setup.c
+++ b/arch/mips/bcm47xx/setup.c
@@ -173,6 +173,31 @@ void __init plat_mem_setup(void)
pm_power_off = bcm47xx_machine_halt;
}

+#ifdef CONFIG_BCM47XX_BCMA
+static struct device * __init bcm47xx_setup_device(void)
+{
+ struct device *dev;
+ int err;
+
+ dev = kzalloc(sizeof(*dev), GFP_KERNEL);
+ if (!dev)
+ return NULL;
+
+ err = dev_set_name(dev, "bcm47xx_soc");
+ if (err) {
+ pr_err("Failed to set SoC device name: %d\n", err);
+ kfree(dev);
+ return NULL;
+ }
+
+ err = dma_coerce_mask_and_coherent(dev, DMA_BIT_MASK(32));
+ if (err)
+ pr_err("Failed to set SoC DMA mask: %d\n", err);
+
+ return dev;
+}
+#endif
+
/*
* This finishes bus initialization doing things that were not possible without
* kmalloc. Make sure to call it late enough (after mm_init).
@@ -183,6 +208,10 @@ void __init bcm47xx_bus_setup(void)
if (bcm47xx_bus_type == BCM47XX_BUS_TYPE_BCMA) {
int err;

+ bcm47xx_bus.bcma.dev = bcm47xx_setup_device();
+ if (!bcm47xx_bus.bcma.dev)
+ panic("Failed to setup SoC device\n");
+
err = bcma_host_soc_init(&bcm47xx_bus.bcma);
if (err)
panic("Failed to initialize BCMA bus (err %d)", err);
@@ -235,6 +264,8 @@ static int __init bcm47xx_register_bus_complete(void)
#endif
#ifdef CONFIG_BCM47XX_BCMA
case BCM47XX_BUS_TYPE_BCMA:
+ if (device_register(bcm47xx_bus.bcma.dev))
+ pr_err("Failed to register SoC device\n");
bcma_bus_register(&bcm47xx_bus.bcma.bus);
break;
#endif
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
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