MIPS: Alchemy: Determine cohereny at runtime based on cpu type

All Alchemy chips have coherent DMA, but for example the USB or AC97
peripherals on the Au1000/1500/1100 are not.
This patch uses DMA_MAYBE_COHERENT on Alchemy and sets coherentio based
on CPU type.

Signed-off-by: Manuel Lauss <manuel.lauss@gmail.com>
Cc: Linux-MIPS <linux-mips@linux-mips.org>
Patchwork: https://patchwork.linux-mips.org/patch/6576/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

4 files changed, 13 insertions, 8 deletions

diff --git a/arch/mips/Kconfig b/arch/mips/Kconfig
index daef6709db15..51f5a09f179d 100644
--- a/arch/mips/Kconfig
+++ b/arch/mips/Kconfig
@@ -63,6 +63,7 @@ config MIPS_ALCHEMY
         select CEVT_R4K
         select CSRC_R4K
         select IRQ_CPU
+        select DMA_MAYBE_COHERENT       # Au1000,1500,1100 aren't, rest is
         select SYS_HAS_CPU_MIPS32_R1
         select SYS_SUPPORTS_32BIT_KERNEL
         select SYS_SUPPORTS_APM_EMULATION
diff --git a/arch/mips/alchemy/Kconfig b/arch/mips/alchemy/Kconfig
index 7032ac7ecd1b..41386723f9fa 100644
--- a/arch/mips/alchemy/Kconfig
+++ b/arch/mips/alchemy/Kconfig
@@ -20,7 +20,6 @@ choice
 
 config MIPS_MTX1
         bool "4G Systems MTX-1 board"
-        select DMA_NONCOHERENT
         select HW_HAS_PCI
         select ALCHEMY_GPIOINT_AU1000
         select SYS_SUPPORTS_LITTLE_ENDIAN
@@ -29,7 +28,6 @@ config MIPS_MTX1
 config MIPS_DB1000
         bool "Alchemy DB1000/DB1500/DB1100 PB1500/1100 boards"
         select ALCHEMY_GPIOINT_AU1000
-        select DMA_NONCOHERENT
         select HW_HAS_PCI
         select SYS_SUPPORTS_BIG_ENDIAN
         select SYS_SUPPORTS_LITTLE_ENDIAN
@@ -39,13 +37,11 @@ config MIPS_DB1235
         bool "Alchemy DB1200/PB1200/DB1300/DB1550/PB1550 boards"
         select ARCH_REQUIRE_GPIOLIB
         select HW_HAS_PCI
-        select DMA_COHERENT
         select SYS_SUPPORTS_LITTLE_ENDIAN
         select SYS_HAS_EARLY_PRINTK
 
 config MIPS_XXS1500
         bool "MyCable XXS1500 board"
-        select DMA_NONCOHERENT
         select ALCHEMY_GPIOINT_AU1000
         select SYS_SUPPORTS_LITTLE_ENDIAN
         select SYS_HAS_EARLY_PRINTK
@@ -54,7 +50,6 @@ config MIPS_GPR
         bool "Trapeze ITS GPR board"
         select ALCHEMY_GPIOINT_AU1000
         select HW_HAS_PCI
-        select DMA_NONCOHERENT
         select SYS_SUPPORTS_LITTLE_ENDIAN
         select SYS_HAS_EARLY_PRINTK
 
diff --git a/arch/mips/alchemy/common/setup.c b/arch/mips/alchemy/common/setup.c
index 62b4e7bbeab9..566a1743f685 100644
--- a/arch/mips/alchemy/common/setup.c
+++ b/arch/mips/alchemy/common/setup.c
@@ -30,6 +30,7 @@
 #include <linux/jiffies.h>
 #include <linux/module.h>
 
+#include <asm/dma-coherence.h>
 #include <asm/mipsregs.h>
 #include <asm/time.h>
 
@@ -59,6 +60,15 @@ void __init plat_mem_setup(void)
                 /* Clear to obtain best system bus performance */
                 clear_c0_config(1 << 19); /* Clear Config[OD] */
 
+        hw_coherentio = 0;
+        coherentio = 1;
+        switch (alchemy_get_cputype()) {
+        case ALCHEMY_CPU_AU1000:
+        case ALCHEMY_CPU_AU1500:
+        case ALCHEMY_CPU_AU1100:
+                coherentio = 0;
+        }
+
         board_setup();  /* board specific setup */
 
         /* IO/MEM resources. */
diff --git a/arch/mips/pci/pci-alchemy.c b/arch/mips/pci/pci-alchemy.c
index d1faece21b6a..563d1f61d6ee 100644
--- a/arch/mips/pci/pci-alchemy.c
+++ b/arch/mips/pci/pci-alchemy.c
@@ -16,6 +16,7 @@
 #include <linux/syscore_ops.h>
 #include <linux/vmalloc.h>
 
+#include <asm/dma-coherence.h>
 #include <asm/mach-au1x00/au1000.h>
 #include <asm/tlbmisc.h>
 
@@ -411,17 +412,15 @@ static int alchemy_pci_probe(struct platform_device *pdev)
         }
         ctx->alchemy_pci_ctrl.io_map_base = (unsigned long)virt_io;
 
-#ifdef CONFIG_DMA_NONCOHERENT
         /* Au1500 revisions older than AD have borked coherent PCI */
         if ((alchemy_get_cputype() == ALCHEMY_CPU_AU1500) &&
-            (read_c0_prid() < 0x01030202)) {
+            (read_c0_prid() < 0x01030202) && !coherentio) {
                 val = __raw_readl(ctx->regs + PCI_REG_CONFIG);
                 val |= PCI_CONFIG_NC;
                 __raw_writel(val, ctx->regs + PCI_REG_CONFIG);
                 wmb();
                 dev_info(&pdev->dev, "non-coherent PCI on Au1500 AA/AB/AC\n");
         }
-#endif
 
         if (pd->board_map_irq)
                 ctx->board_map_irq = pd->board_map_irq;