[PATCH 0/4] ARM: footbridge: cleanups

[PATCH 0/4] ARM: footbridge: cleanups

[Arnd Bergmann]

From: Arnd Bergmann <arnd@arndb.de>

I had an older patch to remove the addin mode for footbridge,
which nobody is using any more, and I found a few other small
cleanups that are worth doing here.

Footbridge is now the only platform with a custom __virt_to_bus()
for ISA DMA, and a custom phys_to_dma() for PCI devices. Both
just add a fixed offset, so there is probably a better way
of doing the same without a custom helper function.

     Arnd

Arnd Bergmann (4):
  ARM: footbridge: remove addin mode
  ARM: footbridge: remove leftover from personal-server
  ARM: footbridge: move isa-dma support into footbridge
  ARM: footbridge: limit CONFIG_ISA to CATS

 arch/arm/Kconfig                              |  5 --
 arch/arm/include/asm/hardware/dec21285.h      | 13 ----
 arch/arm/kernel/Makefile                      |  1 -
 arch/arm/mach-footbridge/Kconfig              | 30 +-------
 arch/arm/mach-footbridge/Makefile             |  5 +-
 arch/arm/mach-footbridge/common.c             | 73 ++-----------------
 arch/arm/mach-footbridge/dc21285.c            | 61 +++++-----------
 .../arm/{kernel => mach-footbridge}/dma-isa.c |  7 +-
 arch/arm/mach-footbridge/dma.c                | 58 ---------------
 .../mach-footbridge/include/mach/isa-dma.h    | 14 +---
 .../arm/mach-footbridge/include/mach/memory.h | 22 ------
 arch/arm/mach-footbridge/isa.c                | 14 ++--
 drivers/tty/serial/21285.c                    |  3 -
 13 files changed, 42 insertions(+), 264 deletions(-)
 rename arch/arm/{kernel => mach-footbridge}/dma-isa.c (98%)
 delete mode 100644 arch/arm/mach-footbridge/dma.c

-- 
2.29.2

Cc: Russell King <linux@armlinux.org.uk>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Linus Walleij <linus.walleij@linaro.org>
Cc: Marc Zyngier <maz@kernel.org>

[PATCH 1/4] ARM: footbridge: remove addin mode

[Arnd Bergmann]

From: Arnd Bergmann <arnd@arndb.de>

This does not appear to have been used in many years, we can
kill off some of the uglier code.

Among other things, it avoids a randconfig issue when both modes
are disabled:

arch/arm/mach-footbridge/common.c:149:24: error: 'ebsa285_host_io_desc' defined but not used [-Werror=unused-variable]
  149 | static struct map_desc ebsa285_host_io_desc[] __initdata = {
      |                        ^~~~~~~~~~~~~~~~~~~~
arch/arm/mach-footbridge/common.c:136:24: error: 'fb_common_io_desc' defined but not used [-Werror=unused-variable]
  136 | static struct map_desc fb_common_io_desc[] __initdata = {
      |                        ^~~~~~~~~~~~~~~~~

The recently added phys_to_dma() functions are now trivial and
could probably be removed again as a follow-up, if anyone knows
how.

Cc: Christoph Hellwig <hch@lst.de>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
---
 arch/arm/include/asm/hardware/dec21285.h      | 13 ----
 arch/arm/mach-footbridge/Kconfig              | 28 +------
 arch/arm/mach-footbridge/Makefile             |  2 +-
 arch/arm/mach-footbridge/common.c             | 73 ++-----------------
 arch/arm/mach-footbridge/dc21285.c            | 61 +++++-----------
 arch/arm/mach-footbridge/dma.c                |  3 +-
 .../arm/mach-footbridge/include/mach/memory.h | 22 ------
 arch/arm/mach-footbridge/isa.c                |  3 -
 8 files changed, 30 insertions(+), 175 deletions(-)

diff --git a/arch/arm/include/asm/hardware/dec21285.h b/arch/arm/include/asm/hardware/dec21285.h
index 3f18a56a025d..eee390e8d4dc 100644
--- a/arch/arm/include/asm/hardware/dec21285.h
+++ b/arch/arm/include/asm/hardware/dec21285.h
@@ -81,19 +81,6 @@
 #define SA110_CNTL_XCSDIR(x)		((x)<<28)
 #define SA110_CNTL_PCICFN		(1 << 31)
 
-/*
- * footbridge_cfn_mode() is used when we want
- * to check whether we are the central function
- */
-#define __footbridge_cfn_mode() (*CSR_SA110_CNTL & SA110_CNTL_PCICFN)
-#if defined(CONFIG_FOOTBRIDGE_HOST) && defined(CONFIG_FOOTBRIDGE_ADDIN)
-#define footbridge_cfn_mode() __footbridge_cfn_mode()
-#elif defined(CONFIG_FOOTBRIDGE_HOST)
-#define footbridge_cfn_mode() (1)
-#else
-#define footbridge_cfn_mode() (0)
-#endif
-
 #define CSR_PCIADDR_EXTN	DC21285_IO(0x0140)
 #define CSR_PREFETCHMEMRANGE	DC21285_IO(0x0144)
 #define CSR_XBUS_CYCLE		DC21285_IO(0x0148)
diff --git a/arch/arm/mach-footbridge/Kconfig b/arch/arm/mach-footbridge/Kconfig
index acc10b1caa69..3497ea8e91e3 100644
--- a/arch/arm/mach-footbridge/Kconfig
+++ b/arch/arm/mach-footbridge/Kconfig
@@ -8,31 +8,17 @@ config ARCH_CATS
 	depends on UNUSED_BOARD_FILES
 	select CLKEVT_I8253
 	select CLKSRC_I8253
-	select FOOTBRIDGE_HOST
 	select ISA
-	select ISA_DMA
 	select FORCE_PCI
 	help
 	  Say Y here if you intend to run this kernel on the CATS.
 
 	  Saying N will reduce the size of the Footbridge kernel.
 
-config ARCH_EBSA285_ADDIN
-	bool "EBSA285 (addin mode)"
-	select ARCH_EBSA285
-	select FOOTBRIDGE_ADDIN
-	help
-	  Say Y here if you intend to run this kernel on the EBSA285 card
-	  in addin mode.
-
-	  Saying N will reduce the size of the Footbridge kernel.
-
 config ARCH_EBSA285_HOST
 	bool "EBSA285 (host mode)"
 	select ARCH_EBSA285
-	select FOOTBRIDGE_HOST
 	select ISA
-	select ISA_DMA
 	select ARCH_MAY_HAVE_PC_FDC
 	select FORCE_PCI
 	help
@@ -45,9 +31,7 @@ config ARCH_NETWINDER
 	bool "NetWinder"
 	select CLKEVT_I8253
 	select CLKSRC_I8253
-	select FOOTBRIDGE_HOST
 	select ISA
-	select ISA_DMA
 	select FORCE_PCI
 	help
 	  Say Y here if you intend to run this kernel on the Rebel.COM
@@ -61,19 +45,11 @@ endmenu
 
 # Footbridge support
 config FOOTBRIDGE
+	def_bool y
 	select ARCH_HAS_PHYS_TO_DMA
-	bool
-
-# Footbridge in host mode
-config FOOTBRIDGE_HOST
-	bool
 	select ARCH_MIGHT_HAVE_PC_SERIO
+	select ISA_DMA
 
-# Footbridge in addin mode
-config FOOTBRIDGE_ADDIN
-	bool
-
-# EBSA285 board in either host or addin mode
 config ARCH_EBSA285
 	bool
 
diff --git a/arch/arm/mach-footbridge/Makefile b/arch/arm/mach-footbridge/Makefile
index 6262993c0555..30bae6684dce 100644
--- a/arch/arm/mach-footbridge/Makefile
+++ b/arch/arm/mach-footbridge/Makefile
@@ -9,7 +9,7 @@ obj-y			:= common.o dma.o isa-irq.o
 
 pci-y			+= dc21285.o
 pci-$(CONFIG_ARCH_CATS) += cats-pci.o
-pci-$(CONFIG_ARCH_EBSA285_HOST) += ebsa285-pci.o
+pci-$(CONFIG_ARCH_EBSA285) += ebsa285-pci.o
 pci-$(CONFIG_ARCH_NETWINDER) += netwinder-pci.o
 
 obj-$(CONFIG_ARCH_CATS) += cats-hw.o isa-timer.o
diff --git a/arch/arm/mach-footbridge/common.c b/arch/arm/mach-footbridge/common.c
index 5020eb96b025..9483eccea5ae 100644
--- a/arch/arm/mach-footbridge/common.c
+++ b/arch/arm/mach-footbridge/common.c
@@ -198,9 +198,6 @@ void __init footbridge_init_irq(void)
 
 	__fb_init_irq();
 
-	if (!footbridge_cfn_mode())
-		return;
-
 	if (machine_is_ebsa285())
 		/* The following is dependent on which slot
 		 * you plug the Southbridge card into.  We
@@ -221,21 +218,13 @@ void __init footbridge_init_irq(void)
  * commented out since there is a "No Fix" problem with it.  Not mapping
  * it means that we have extra bullet protection on our feet.
  */
-static struct map_desc fb_common_io_desc[] __initdata = {
+static struct map_desc ebsa285_host_io_desc[] __initdata = {
 	{
 		.virtual	= ARMCSR_BASE,
 		.pfn		= __phys_to_pfn(DC21285_ARMCSR_BASE),
 		.length		= ARMCSR_SIZE,
 		.type		= MT_DEVICE,
-	}
-};
-
-/*
- * The mapping when the footbridge is in host mode.  We don't map any of
- * this when we are in add-in mode.
- */
-static struct map_desc ebsa285_host_io_desc[] __initdata = {
-#if defined(CONFIG_ARCH_FOOTBRIDGE) && defined(CONFIG_FOOTBRIDGE_HOST)
+	},
 	{
 		.virtual	= PCIMEM_BASE,
 		.pfn		= __phys_to_pfn(DC21285_PCI_MEM),
@@ -257,26 +246,12 @@ static struct map_desc ebsa285_host_io_desc[] __initdata = {
 		.length		= PCIIACK_SIZE,
 		.type		= MT_DEVICE,
 	},
-#endif
 };
 
 void __init footbridge_map_io(void)
 {
-	/*
-	 * Set up the common mapping first; we need this to
-	 * determine whether we're in host mode or not.
-	 */
-	iotable_init(fb_common_io_desc, ARRAY_SIZE(fb_common_io_desc));
-
-	/*
-	 * Now, work out what we've got to map in addition on this
-	 * platform.
-	 */
-	if (footbridge_cfn_mode()) {
-		iotable_init(ebsa285_host_io_desc, ARRAY_SIZE(ebsa285_host_io_desc));
-		pci_map_io_early(__phys_to_pfn(DC21285_PCI_IO));
-	}
-
+	iotable_init(ebsa285_host_io_desc, ARRAY_SIZE(ebsa285_host_io_desc));
+	pci_map_io_early(__phys_to_pfn(DC21285_PCI_IO));
 	vga_base = PCIMEM_BASE;
 }
 
@@ -307,48 +282,12 @@ void footbridge_restart(enum reboot_mode mode, const char *cmd)
 	}
 }
 
-#ifdef CONFIG_FOOTBRIDGE_ADDIN
-
-static inline unsigned long fb_bus_sdram_offset(void)
-{
-	return *CSR_PCISDRAMBASE & 0xfffffff0;
-}
-
-/*
- * These two functions convert virtual addresses to PCI addresses and PCI
- * addresses to virtual addresses.  Note that it is only legal to use these
- * on memory obtained via get_zeroed_page or kmalloc.
- */
-unsigned long __virt_to_bus(unsigned long res)
-{
-	WARN_ON(res < PAGE_OFFSET || res >= (unsigned long)high_memory);
-
-	return res + (fb_bus_sdram_offset() - PAGE_OFFSET);
-}
-EXPORT_SYMBOL(__virt_to_bus);
-
-unsigned long __bus_to_virt(unsigned long res)
-{
-	res = res - (fb_bus_sdram_offset() - PAGE_OFFSET);
-
-	WARN_ON(res < PAGE_OFFSET || res >= (unsigned long)high_memory);
-
-	return res;
-}
-EXPORT_SYMBOL(__bus_to_virt);
-#else
-static inline unsigned long fb_bus_sdram_offset(void)
-{
-	return BUS_OFFSET;
-}
-#endif /* CONFIG_FOOTBRIDGE_ADDIN */
-
 dma_addr_t phys_to_dma(struct device *dev, phys_addr_t paddr)
 {
-	return paddr + (fb_bus_sdram_offset() - PHYS_OFFSET);
+	return paddr + (BUS_OFFSET - PHYS_OFFSET);
 }
 
 phys_addr_t dma_to_phys(struct device *dev, dma_addr_t dev_addr)
 {
-	return dev_addr - (fb_bus_sdram_offset() - PHYS_OFFSET);
+	return dev_addr - (BUS_OFFSET - PHYS_OFFSET);
 }
diff --git a/arch/arm/mach-footbridge/dc21285.c b/arch/arm/mach-footbridge/dc21285.c
index f9713dc561cf..372600bc15c8 100644
--- a/arch/arm/mach-footbridge/dc21285.c
+++ b/arch/arm/mach-footbridge/dc21285.c
@@ -245,9 +245,6 @@ int __init dc21285_setup(int nr, struct pci_sys_data *sys)
 {
 	struct resource *res;
 
-	if (nr || !footbridge_cfn_mode())
-		return 0;
-
 	res = kcalloc(2, sizeof(struct resource), GFP_KERNEL);
 	if (!res) {
 		printk("out of memory for root bus resources");
@@ -278,7 +275,6 @@ int __init dc21285_setup(int nr, struct pci_sys_data *sys)
 void __init dc21285_preinit(void)
 {
 	unsigned int mem_size, mem_mask;
-	int cfn_mode;
 
 	pcibios_min_mem = 0x81000000;
 
@@ -298,21 +294,15 @@ void __init dc21285_preinit(void)
 	*CSR_CSRBASEOFFSET    = 0;
 	*CSR_PCIADDR_EXTN     = 0;
 
-	cfn_mode = __footbridge_cfn_mode();
-
 	printk(KERN_INFO "PCI: DC21285 footbridge, revision %02lX, in "
-		"%s mode\n", *CSR_CLASSREV & 0xff, cfn_mode ?
-		"central function" : "addin");
-
-	if (footbridge_cfn_mode()) {
-		/*
-		 * Clear any existing errors - we aren't
-		 * interested in historical data...
-		 */
-		*CSR_SA110_CNTL	= (*CSR_SA110_CNTL & 0xffffde07) |
-				  SA110_CNTL_RXSERR;
-		*CSR_PCICMD = (*CSR_PCICMD & 0xffff) | PCICMD_ERROR_BITS;
-	}
+		"central function mode\n", *CSR_CLASSREV & 0xff);
+
+	/*
+	 * Clear any existing errors - we aren't
+	 * interested in historical data...
+	 */
+	*CSR_SA110_CNTL	= (*CSR_SA110_CNTL & 0xffffde07) | SA110_CNTL_RXSERR;
+	*CSR_PCICMD = (*CSR_PCICMD & 0xffff) | PCICMD_ERROR_BITS;
 
 	timer_setup(&serr_timer, dc21285_enable_error, 0);
 	timer_setup(&perr_timer, dc21285_enable_error, 0);
@@ -331,29 +321,18 @@ void __init dc21285_preinit(void)
 	dc21285_request_irq(IRQ_PCI_DPERR, dc21285_dparity_irq, 0,
 			    "PCI data parity", NULL);
 
-	if (cfn_mode) {
-		/*
-		 * Map our SDRAM at a known address in PCI space, just in case
-		 * the firmware had other ideas.  Using a nonzero base is
-		 * necessary, since some VGA cards forcefully use PCI addresses
-		 * in the range 0x000a0000 to 0x000c0000. (eg, S3 cards).
-		 */
-		*CSR_PCICSRBASE       = 0xf4000000;
-		*CSR_PCICSRIOBASE     = 0;
-		*CSR_PCISDRAMBASE     = __virt_to_bus(PAGE_OFFSET);
-		*CSR_PCIROMBASE       = 0;
-		*CSR_PCICMD = PCI_COMMAND_MEMORY | PCI_COMMAND_MASTER |
-			      PCI_COMMAND_INVALIDATE | PCICMD_ERROR_BITS;
-	} else if (footbridge_cfn_mode() != 0) {
-		/*
-		 * If we are not compiled to accept "add-in" mode, then
-		 * we are using a constant virt_to_bus translation which
-		 * can not hope to cater for the way the host BIOS  has
-		 * set up the machine.
-		 */
-		panic("PCI: this kernel is compiled for central "
-			"function mode only");
-	}
+	/*
+	 * Map our SDRAM at a known address in PCI space, just in case
+	 * the firmware had other ideas.  Using a nonzero base is
+	 * necessary, since some VGA cards forcefully use PCI addresses
+	 * in the range 0x000a0000 to 0x000c0000. (eg, S3 cards).
+	 */
+	*CSR_PCICSRBASE       = 0xf4000000;
+	*CSR_PCICSRIOBASE     = 0;
+	*CSR_PCISDRAMBASE     = __virt_to_bus(PAGE_OFFSET);
+	*CSR_PCIROMBASE       = 0;
+	*CSR_PCICMD = PCI_COMMAND_MEMORY | PCI_COMMAND_MASTER |
+		      PCI_COMMAND_INVALIDATE | PCICMD_ERROR_BITS;
 }
 
 void __init dc21285_postinit(void)
diff --git a/arch/arm/mach-footbridge/dma.c b/arch/arm/mach-footbridge/dma.c
index 86618074a7a5..228757c8e06f 100644
--- a/arch/arm/mach-footbridge/dma.c
+++ b/arch/arm/mach-footbridge/dma.c
@@ -50,8 +50,7 @@ static int __init fb_dma_init(void)
 	dma[_DC21285_DMA(1)].d_ops = &fb_dma_ops;
 #endif
 #ifdef CONFIG_ISA_DMA
-	if (footbridge_cfn_mode())
-		isa_init_dma();
+	isa_init_dma();
 #endif
 	return 0;
 }
diff --git a/arch/arm/mach-footbridge/include/mach/memory.h b/arch/arm/mach-footbridge/include/mach/memory.h
index 3a5d2638c18f..8f0ca8e8b37e 100644
--- a/arch/arm/mach-footbridge/include/mach/memory.h
+++ b/arch/arm/mach-footbridge/include/mach/memory.h
@@ -16,22 +16,6 @@
 #ifndef __ASM_ARCH_MEMORY_H
 #define __ASM_ARCH_MEMORY_H
 
-
-#if defined(CONFIG_FOOTBRIDGE_ADDIN)
-/*
- * If we may be using add-in footbridge mode, then we must
- * use the out-of-line translation that makes use of the
- * PCI BAR
- */
-#ifndef __ASSEMBLY__
-extern unsigned long __virt_to_bus(unsigned long);
-extern unsigned long __bus_to_virt(unsigned long);
-#endif
-#define __virt_to_bus	__virt_to_bus
-#define __bus_to_virt	__bus_to_virt
-
-#elif defined(CONFIG_FOOTBRIDGE_HOST)
-
 /*
  * The footbridge is programmed to expose the system RAM at 0xe0000000.
  * The requirement is that the RAM isn't placed at bus address 0, which
@@ -41,12 +25,6 @@ extern unsigned long __bus_to_virt(unsigned long);
 #define __virt_to_bus(x)	((x) + (BUS_OFFSET - PAGE_OFFSET))
 #define __bus_to_virt(x)	((x) - (BUS_OFFSET - PAGE_OFFSET))
 
-#else
-
-#error "Undefined footbridge mode"
-
-#endif
-
 /*
  * Cache flushing area.
  */
diff --git a/arch/arm/mach-footbridge/isa.c b/arch/arm/mach-footbridge/isa.c
index ec5af521cf95..3375ac23c046 100644
--- a/arch/arm/mach-footbridge/isa.c
+++ b/arch/arm/mach-footbridge/isa.c
@@ -79,9 +79,6 @@ static int __init footbridge_isa_init(void)
 {
 	int err = 0;
 
-	if (!footbridge_cfn_mode())
-		return 0;
-
 	/* Personal server doesn't have RTC */
 	if (!machine_is_personal_server()) {
 		isa_rtc_init();
-- 
2.29.2

[PATCH 2/4] ARM: footbridge: remove leftover from personal-server

[Arnd Bergmann]

From: Arnd Bergmann <arnd@arndb.de>

The machine was removed a while ago, and the checks are
now useless.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
---
 arch/arm/mach-footbridge/isa.c | 11 +++++------
 drivers/tty/serial/21285.c     |  3 ---
 2 files changed, 5 insertions(+), 9 deletions(-)

diff --git a/arch/arm/mach-footbridge/isa.c b/arch/arm/mach-footbridge/isa.c
index 3375ac23c046..84caccddce44 100644
--- a/arch/arm/mach-footbridge/isa.c
+++ b/arch/arm/mach-footbridge/isa.c
@@ -80,12 +80,11 @@ static int __init footbridge_isa_init(void)
 	int err = 0;
 
 	/* Personal server doesn't have RTC */
-	if (!machine_is_personal_server()) {
-		isa_rtc_init();
-		err = platform_device_register(&rtc_device);
-		if (err)
-			printk(KERN_ERR "Unable to register RTC device: %d\n", err);
-	}
+	isa_rtc_init();
+	err = platform_device_register(&rtc_device);
+	if (err)
+		printk(KERN_ERR "Unable to register RTC device: %d\n", err);
+
 	err = platform_device_register(&serial_device);
 	if (err)
 		printk(KERN_ERR "Unable to register serial device: %d\n", err);
diff --git a/drivers/tty/serial/21285.c b/drivers/tty/serial/21285.c
index 7520cc02fd4d..65d6af755567 100644
--- a/drivers/tty/serial/21285.c
+++ b/drivers/tty/serial/21285.c
@@ -461,9 +461,6 @@ static int __init serial21285_console_setup(struct console *co, char *options)
 	int parity = 'n';
 	int flow = 'n';
 
-	if (machine_is_personal_server())
-		baud = 57600;
-
 	/*
 	 * Check whether an invalid uart number has been specified, and
 	 * if so, search for the first available port that does have
-- 
2.29.2

[PATCH 3/4] ARM: footbridge: move isa-dma support into footbridge

[Arnd Bergmann]

From: Arnd Bergmann <arnd@arndb.de>

The dma-isa.c was shared between footbridge and shark a long time ago,
but as shark was removed, it can be made footbridge specific again.

The fb_dma bits in turn are not used at all and can be removed.

All the ISA related files are now built into the platform regardless
of CONFIG_ISA, as they just refer to on-chip devices rather than actual
ISA cards.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
---
 arch/arm/Kconfig                              |  5 --
 arch/arm/kernel/Makefile                      |  1 -
 arch/arm/mach-footbridge/Kconfig              |  2 +-
 arch/arm/mach-footbridge/Makefile             |  3 +-
 .../arm/{kernel => mach-footbridge}/dma-isa.c |  7 ++-
 arch/arm/mach-footbridge/dma.c                | 57 -------------------
 .../mach-footbridge/include/mach/isa-dma.h    | 14 +----
 7 files changed, 9 insertions(+), 80 deletions(-)
 rename arch/arm/{kernel => mach-footbridge}/dma-isa.c (98%)
 delete mode 100644 arch/arm/mach-footbridge/dma.c

diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index 87badeae3181..ec7e48f6bd91 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -989,11 +989,6 @@ config ISA
 	  (MCA) or VESA.  ISA is an older system, now being displaced by PCI;
 	  newer boards don't support it.  If you have ISA, say Y, otherwise N.
 
-# Select ISA DMA controller support
-config ISA_DMA
-	bool
-	select ISA_DMA_API
-
 # Select ISA DMA interface
 config ISA_DMA_API
 	bool
diff --git a/arch/arm/kernel/Makefile b/arch/arm/kernel/Makefile
index 553866751e1a..95034d32213c 100644
--- a/arch/arm/kernel/Makefile
+++ b/arch/arm/kernel/Makefile
@@ -45,7 +45,6 @@ obj-$(CONFIG_ISA_DMA_API)	+= dma.o
 obj-$(CONFIG_FIQ)		+= fiq.o fiqasm.o
 obj-$(CONFIG_MODULES)		+= armksyms.o module.o
 obj-$(CONFIG_ARM_MODULE_PLTS)	+= module-plts.o
-obj-$(CONFIG_ISA_DMA)		+= dma-isa.o
 obj-$(CONFIG_PCI)		+= bios32.o isa.o
 obj-$(CONFIG_ARM_CPU_SUSPEND)	+= sleep.o suspend.o
 obj-$(CONFIG_HIBERNATION)	+= hibernate.o
diff --git a/arch/arm/mach-footbridge/Kconfig b/arch/arm/mach-footbridge/Kconfig
index 3497ea8e91e3..1a3676109654 100644
--- a/arch/arm/mach-footbridge/Kconfig
+++ b/arch/arm/mach-footbridge/Kconfig
@@ -48,7 +48,7 @@ config FOOTBRIDGE
 	def_bool y
 	select ARCH_HAS_PHYS_TO_DMA
 	select ARCH_MIGHT_HAVE_PC_SERIO
-	select ISA_DMA
+	select ISA_DMA_API
 
 config ARCH_EBSA285
 	bool
diff --git a/arch/arm/mach-footbridge/Makefile b/arch/arm/mach-footbridge/Makefile
index 30bae6684dce..55d570739f19 100644
--- a/arch/arm/mach-footbridge/Makefile
+++ b/arch/arm/mach-footbridge/Makefile
@@ -5,7 +5,7 @@
 
 # Object file lists.
 
-obj-y			:= common.o dma.o isa-irq.o
+obj-y			:= common.o isa-irq.o isa.o isa-rtc.o dma-isa.o
 
 pci-y			+= dc21285.o
 pci-$(CONFIG_ARCH_CATS) += cats-pci.o
@@ -18,4 +18,3 @@ obj-$(CONFIG_ARCH_NETWINDER) += netwinder-hw.o isa-timer.o
 
 obj-$(CONFIG_PCI)	+=$(pci-y)
 
-obj-$(CONFIG_ISA)	+= isa.o isa-rtc.o
diff --git a/arch/arm/kernel/dma-isa.c b/arch/arm/mach-footbridge/dma-isa.c
similarity index 98%
rename from arch/arm/kernel/dma-isa.c
rename to arch/arm/mach-footbridge/dma-isa.c
index 2d90ecce5a11..e45bc31b0959 100644
--- a/arch/arm/kernel/dma-isa.c
+++ b/arch/arm/mach-footbridge/dma-isa.c
@@ -1,7 +1,5 @@
 // SPDX-License-Identifier: GPL-2.0-only
 /*
- *  linux/arch/arm/kernel/dma-isa.c
- *
  *  Copyright (C) 1999-2000 Russell King
  *
  *  ISA DMA primitives
@@ -157,7 +155,7 @@ static dma_t isa_dma[8];
 /*
  * ISA DMA always starts at channel 0
  */
-void __init isa_init_dma(void)
+static int __init isa_init_dma(void)
 {
 	/*
 	 * Try to autodetect presence of an ISA DMA controller.
@@ -222,4 +220,7 @@ void __init isa_init_dma(void)
 
 		request_dma(DMA_ISA_CASCADE, "cascade");
 	}
+
+	return 0;
 }
+core_initcall(isa_dma_init);
diff --git a/arch/arm/mach-footbridge/dma.c b/arch/arm/mach-footbridge/dma.c
deleted file mode 100644
index 228757c8e06f..000000000000
--- a/arch/arm/mach-footbridge/dma.c
+++ /dev/null
@@ -1,57 +0,0 @@
-// SPDX-License-Identifier: GPL-2.0
-/*
- *  linux/arch/arm/kernel/dma-ebsa285.c
- *
- *  Copyright (C) 1998 Phil Blundell
- *
- * DMA functions specific to EBSA-285/CATS architectures
- *
- *  Changelog:
- *   09-Nov-1998 RMK	Split out ISA DMA functions to dma-isa.c
- *   17-Mar-1999 RMK	Allow any EBSA285-like architecture to have
- *			ISA DMA controllers.
- */
-#include <linux/init.h>
-#include <linux/io.h>
-#include <linux/spinlock.h>
-#include <linux/scatterlist.h>
-
-#include <asm/dma.h>
-
-#include <asm/mach/dma.h>
-#include <asm/hardware/dec21285.h>
-
-#if 0
-static int fb_dma_request(unsigned int chan, dma_t *dma)
-{
-	return -EINVAL;
-}
-
-static void fb_dma_enable(unsigned int chan, dma_t *dma)
-{
-}
-
-static void fb_dma_disable(unsigned int chan, dma_t *dma)
-{
-}
-
-static struct dma_ops fb_dma_ops = {
-	.type		= "fb",
-	.request	= fb_dma_request,
-	.enable		= fb_dma_enable,
-	.disable	= fb_dma_disable,
-};
-#endif
-
-static int __init fb_dma_init(void)
-{
-#if 0
-	dma[_DC21285_DMA(0)].d_ops = &fb_dma_ops;
-	dma[_DC21285_DMA(1)].d_ops = &fb_dma_ops;
-#endif
-#ifdef CONFIG_ISA_DMA
-	isa_init_dma();
-#endif
-	return 0;
-}
-core_initcall(fb_dma_init);
diff --git a/arch/arm/mach-footbridge/include/mach/isa-dma.h b/arch/arm/mach-footbridge/include/mach/isa-dma.h
index 8a1b991076e1..b10731a1f66a 100644
--- a/arch/arm/mach-footbridge/include/mach/isa-dma.h
+++ b/arch/arm/mach-footbridge/include/mach/isa-dma.h
@@ -10,17 +10,9 @@
 #ifndef __ASM_ARCH_DMA_H
 #define __ASM_ARCH_DMA_H
 
-/*
- * The 21285 has two internal DMA channels; we call these 8 and 9.
- * On CATS hardware we have an additional eight ISA dma channels
- * numbered 0..7.
- */
-#define _ISA_DMA(x)		(0+(x))
-#define _DC21285_DMA(x)		(8+(x))
-
-#define MAX_DMA_CHANNELS	10
+#define MAX_DMA_CHANNELS	8
 
-#define DMA_FLOPPY		_ISA_DMA(2)
-#define DMA_ISA_CASCADE		_ISA_DMA(4)
+#define DMA_FLOPPY		(2)
+#define DMA_ISA_CASCADE		(4)
 
 #endif /* _ASM_ARCH_DMA_H */
-- 
2.29.2

[PATCH 4/4] ARM: footbridge: limit CONFIG_ISA to CATS

[Arnd Bergmann]

From: Arnd Bergmann <arnd@arndb.de>

The CONFIG_ISA option is only used for actual add-in cards, not
on-board devices. NetWinder has no hardware support for those,
and ebsa285 appears to not support them in Linux, as the XBUS
is not set up that way and there is no support for a PCI-ISA
bridge.

CATS on the other hand has four ISA slots connected to a PCI-ISA
bridge device.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
---
 arch/arm/mach-footbridge/Kconfig | 2 --
 1 file changed, 2 deletions(-)

diff --git a/arch/arm/mach-footbridge/Kconfig b/arch/arm/mach-footbridge/Kconfig
index 1a3676109654..cd18871fd03f 100644
--- a/arch/arm/mach-footbridge/Kconfig
+++ b/arch/arm/mach-footbridge/Kconfig
@@ -18,7 +18,6 @@ config ARCH_CATS
 config ARCH_EBSA285_HOST
 	bool "EBSA285 (host mode)"
 	select ARCH_EBSA285
-	select ISA
 	select ARCH_MAY_HAVE_PC_FDC
 	select FORCE_PCI
 	help
@@ -31,7 +30,6 @@ config ARCH_NETWINDER
 	bool "NetWinder"
 	select CLKEVT_I8253
 	select CLKSRC_I8253
-	select ISA
 	select FORCE_PCI
 	help
 	  Say Y here if you intend to run this kernel on the Rebel.COM
-- 
2.29.2

Re: [PATCH 1/4] ARM: footbridge: remove addin mode

[Christoph Hellwig]

On Thu, Aug 18, 2022 at 11:15:47PM +0200, Arnd Bergmann wrote:
> The recently added phys_to_dma() functions are now trivial and
> could probably be removed again as a follow-up, if anyone knows
> how.

The normal way to that would be with a call to dma_direct_set_offset in
the init code.  But for that we'd need to find someone to care enough
about footbridge to test it.

Re: [PATCH 2/4] ARM: footbridge: remove leftover from personal-server

[Christoph Hellwig]

On Thu, Aug 18, 2022 at 11:15:48PM +0200, Arnd Bergmann wrote:
> From: Arnd Bergmann <arnd@arndb.de>
> 
> The machine was removed a while ago, and the checks are
> now useless.

Curious, should entries for removed machines be kept in the mach-types
file?  Because that makes it really easy to leave dead code like this
around.

The patch itself looks fine:

Reviewed-by: Christoph Hellwig <hch@lst.de>

Re: [PATCH 3/4] ARM: footbridge: move isa-dma support into footbridge

[Christoph Hellwig]

Looks good:

Reviewed-by: Christoph Hellwig <hch@lst.de>

Re: [PATCH 1/4] ARM: footbridge: remove addin mode

[Arnd Bergmann]

On Sun, Aug 21, 2022 at 7:53 AM Christoph Hellwig <hch@lst.de> wrote:
>
> On Thu, Aug 18, 2022 at 11:15:47PM +0200, Arnd Bergmann wrote:
> > The recently added phys_to_dma() functions are now trivial and
> > could probably be removed again as a follow-up, if anyone knows
> > how.
>
> The normal way to that would be with a call to dma_direct_set_offset in
> the init code.

Ah good, that is what I was looking for. Unfortunately it seems that the
platform does not itself create any 'struct device'. The DMA masters
are either ISA devices, which I think go through a dummy device an
should also use offset 0 (the same offset seems to get added
in dma-mapping code but subtracted again in the ISA DMA API)
and in PCI bus masters.

Is it enough to just call dma_direct_set_offset() on the PCI root
device, or do I have to add a pci_host_bridge callback to get
called from pcibios_bus_add_device()?

>  But for that we'd need to find someone to care enough
> about footbridge to test it.

LinusW, MarcZ and RMK all have one of these, I'm fairly sure
one of them can test the PCI side, though possibly not
the ISA DMA ones (parport, floppy, ne2000, and soundblaster
in case of netwinder).

         Arnd

Re: [PATCH 2/4] ARM: footbridge: remove leftover from personal-server

[Arnd Bergmann]

On Sun, Aug 21, 2022 at 7:55 AM Christoph Hellwig <hch@lst.de> wrote:
>
> On Thu, Aug 18, 2022 at 11:15:48PM +0200, Arnd Bergmann wrote:
> > From: Arnd Bergmann <arnd@arndb.de>
> >
> > The machine was removed a while ago, and the checks are
> > now useless.
>
> Curious, should entries for removed machines be kept in the mach-types
> file?  Because that makes it really easy to leave dead code like this
> around.

A long time ago it was common to add the entries in mach-types before
the Kconfig symbol got merged, an  Russell just updated the list
periodically to drop stale entries. As we remove most board files in
a coming release, we should probably do this as part of the bigger
cleanup then.

        Arnd

Re: [PATCH 2/4] ARM: footbridge: remove leftover from personal-server

[Russell King (Oracle)]

On Wed, Aug 24, 2022 at 12:37:15PM +0200, Arnd Bergmann wrote:
> On Sun, Aug 21, 2022 at 7:55 AM Christoph Hellwig <hch@lst.de> wrote:
> >
> > On Thu, Aug 18, 2022 at 11:15:48PM +0200, Arnd Bergmann wrote:
> > > From: Arnd Bergmann <arnd@arndb.de>
> > >
> > > The machine was removed a while ago, and the checks are
> > > now useless.
> >
> > Curious, should entries for removed machines be kept in the mach-types
> > file?  Because that makes it really easy to leave dead code like this
> > around.
> 
> A long time ago it was common to add the entries in mach-types before
> the Kconfig symbol got merged, an  Russell just updated the list
> periodically to drop stale entries. As we remove most board files in
> a coming release, we should probably do this as part of the bigger
> cleanup then.

The scripting I have for it doesn't understand "board was removed from
the kernel" so if I ever run the script in the future (unlikely) it'll
get re-added.

-- 
RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
FTTP is here! 40Mbps down 10Mbps up. Decent connectivity at last!

[PATCH 5/4] ARM: footbridge: remove custom DMA address handling

[Arnd Bergmann]

From: Arnd Bergmann <arnd@arndb.de>

Footbridge is the last Arm platform that has its own
__virt_to_bus()/__bus_to_virt()/phys_to_dma()/dma_to_phys() abstraction,
but this is just a simple offset now.

For ISA DMA (floppy etc), the offset is actually zero, so the special
hack to subtract the bus offset can be removed from common code.

For PCI devices, the offset that is programmed into the PCI bridge
must also be set in each device using dma_direct_set_offset().
As Arm does not have a pcibios_bus_add_device() helper yet, just
use a bus notifier for this.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
---
I added this patch on top of the footbridge series,
the other four are unmodified.

 arch/arm/include/asm/dma-direct.h             |  1 -
 arch/arm/include/asm/dma.h                    |  2 +-
 arch/arm/include/asm/memory.h                 | 11 --------
 arch/arm/mach-footbridge/Kconfig              |  1 -
 arch/arm/mach-footbridge/common.c             | 10 -------
 arch/arm/mach-footbridge/dc21285.c            | 28 ++++++++++++++++++-
 .../mach-footbridge/include/mach/dma-direct.h |  8 ------
 .../arm/mach-footbridge/include/mach/memory.h |  9 ------
 8 files changed, 28 insertions(+), 42 deletions(-)
 delete mode 100644 arch/arm/include/asm/dma-direct.h
 delete mode 100644 arch/arm/mach-footbridge/include/mach/dma-direct.h

diff --git a/arch/arm/include/asm/dma-direct.h b/arch/arm/include/asm/dma-direct.h
deleted file mode 100644
index 4f7bcde03abb..000000000000
--- a/arch/arm/include/asm/dma-direct.h
+++ /dev/null
@@ -1 +0,0 @@
-#include <mach/dma-direct.h>
diff --git a/arch/arm/include/asm/dma.h b/arch/arm/include/asm/dma.h
index 05f29a72150b..ab3863a3cdf2 100644
--- a/arch/arm/include/asm/dma.h
+++ b/arch/arm/include/asm/dma.h
@@ -106,7 +106,7 @@ extern void set_dma_sg(unsigned int chan, struct scatterlist *sg, int nr_sg);
  */
 extern void __set_dma_addr(unsigned int chan, void *addr);
 #define set_dma_addr(chan, addr)				\
-	__set_dma_addr(chan, (void *)__bus_to_virt(addr))
+	__set_dma_addr(chan, (void *)(addr))
 
 /* Set the DMA byte count for this channel
  *
diff --git a/arch/arm/include/asm/memory.h b/arch/arm/include/asm/memory.h
index a55a9038abc8..d8eef4bd8c71 100644
--- a/arch/arm/include/asm/memory.h
+++ b/arch/arm/include/asm/memory.h
@@ -369,17 +369,6 @@ static inline unsigned long __virt_to_idmap(unsigned long x)
 
 #define virt_to_idmap(x)	__virt_to_idmap((unsigned long)(x))
 
-/*
- * Virtual <-> DMA view memory address translations
- * Again, these are *only* valid on the kernel direct mapped RAM
- * memory.  Use of these is *deprecated* (and that doesn't mean
- * use the __ prefixed forms instead.)  See dma-mapping.h.
- */
-#ifndef __virt_to_bus
-#define __virt_to_bus	__virt_to_phys
-#define __bus_to_virt	__phys_to_virt
-#endif
-
 /*
  * Conversion between a struct page and a physical address.
  *
diff --git a/arch/arm/mach-footbridge/Kconfig b/arch/arm/mach-footbridge/Kconfig
index cd18871fd03f..f452663576d1 100644
--- a/arch/arm/mach-footbridge/Kconfig
+++ b/arch/arm/mach-footbridge/Kconfig
@@ -44,7 +44,6 @@ endmenu
 # Footbridge support
 config FOOTBRIDGE
 	def_bool y
-	select ARCH_HAS_PHYS_TO_DMA
 	select ARCH_MIGHT_HAVE_PC_SERIO
 	select ISA_DMA_API
 
diff --git a/arch/arm/mach-footbridge/common.c b/arch/arm/mach-footbridge/common.c
index 9483eccea5ae..629e4676ed77 100644
--- a/arch/arm/mach-footbridge/common.c
+++ b/arch/arm/mach-footbridge/common.c
@@ -281,13 +281,3 @@ void footbridge_restart(enum reboot_mode mode, const char *cmd)
 		*CSR_SA110_CNTL |= (1 << 13);
 	}
 }
-
-dma_addr_t phys_to_dma(struct device *dev, phys_addr_t paddr)
-{
-	return paddr + (BUS_OFFSET - PHYS_OFFSET);
-}
-
-phys_addr_t dma_to_phys(struct device *dev, dma_addr_t dev_addr)
-{
-	return dev_addr - (BUS_OFFSET - PHYS_OFFSET);
-}
diff --git a/arch/arm/mach-footbridge/dc21285.c b/arch/arm/mach-footbridge/dc21285.c
index 372600bc15c8..e34b33a955e2 100644
--- a/arch/arm/mach-footbridge/dc21285.c
+++ b/arch/arm/mach-footbridge/dc21285.c
@@ -5,6 +5,7 @@
  *  Copyright (C) 1998-2001 Russell King
  *  Copyright (C) 1998-2000 Phil Blundell
  */
+#include <linux/dma-map-ops.h>
 #include <linux/kernel.h>
 #include <linux/pci.h>
 #include <linux/interrupt.h>
@@ -241,6 +242,29 @@ static irqreturn_t dc21285_parity_irq(int irq, void *dev_id)
 	return IRQ_HANDLED;
 }
 
+/*
+ * The footbridge is programmed to expose the system RAM at 0xe0000000.
+ * The requirement is that the RAM isn't placed at bus address 0, which
+ * would clash with VGA cards.
+ */
+#define BUS_OFFSET 0xe0000000
+
+static int dc21285_pci_bus_notifier(struct notifier_block *nb,
+				    unsigned long action,
+				    void *data)
+{
+	if (action != BUS_NOTIFY_ADD_DEVICE)
+		return NOTIFY_DONE;
+
+	dma_direct_set_offset(data, PHYS_OFFSET, BUS_OFFSET, SZ_256M);
+
+	return NOTIFY_OK;
+}
+
+static struct notifier_block dc21285_pci_bus_nb = {
+	.notifier_call = dc21285_pci_bus_notifier,
+};
+
 int __init dc21285_setup(int nr, struct pci_sys_data *sys)
 {
 	struct resource *res;
@@ -266,6 +290,8 @@ int __init dc21285_setup(int nr, struct pci_sys_data *sys)
 	pci_add_resource_offset(&sys->resources, &res[0], sys->mem_offset);
 	pci_add_resource_offset(&sys->resources, &res[1], sys->mem_offset);
 
+	bus_register_notifier(&pci_bus_type, &dc21285_pci_bus_nb);
+
 	return 1;
 }
 
@@ -329,7 +355,7 @@ void __init dc21285_preinit(void)
 	 */
 	*CSR_PCICSRBASE       = 0xf4000000;
 	*CSR_PCICSRIOBASE     = 0;
-	*CSR_PCISDRAMBASE     = __virt_to_bus(PAGE_OFFSET);
+	*CSR_PCISDRAMBASE     = BUS_OFFSET;
 	*CSR_PCIROMBASE       = 0;
 	*CSR_PCICMD = PCI_COMMAND_MEMORY | PCI_COMMAND_MASTER |
 		      PCI_COMMAND_INVALIDATE | PCICMD_ERROR_BITS;
diff --git a/arch/arm/mach-footbridge/include/mach/dma-direct.h b/arch/arm/mach-footbridge/include/mach/dma-direct.h
deleted file mode 100644
index 01f9e8367c00..000000000000
--- a/arch/arm/mach-footbridge/include/mach/dma-direct.h
+++ /dev/null
@@ -1,8 +0,0 @@
-/* SPDX-License-Identifier: GPL-2.0 */
-#ifndef MACH_FOOTBRIDGE_DMA_DIRECT_H
-#define MACH_FOOTBRIDGE_DMA_DIRECT_H 1
-
-dma_addr_t phys_to_dma(struct device *dev, phys_addr_t paddr);
-phys_addr_t dma_to_phys(struct device *dev, dma_addr_t dev_addr);
-
-#endif /* MACH_FOOTBRIDGE_DMA_DIRECT_H */
diff --git a/arch/arm/mach-footbridge/include/mach/memory.h b/arch/arm/mach-footbridge/include/mach/memory.h
index 8f0ca8e8b37e..9516877667d7 100644
--- a/arch/arm/mach-footbridge/include/mach/memory.h
+++ b/arch/arm/mach-footbridge/include/mach/memory.h
@@ -16,15 +16,6 @@
 #ifndef __ASM_ARCH_MEMORY_H
 #define __ASM_ARCH_MEMORY_H
 
-/*
- * The footbridge is programmed to expose the system RAM at 0xe0000000.
- * The requirement is that the RAM isn't placed at bus address 0, which
- * would clash with VGA cards.
- */
-#define BUS_OFFSET		0xe0000000
-#define __virt_to_bus(x)	((x) + (BUS_OFFSET - PAGE_OFFSET))
-#define __bus_to_virt(x)	((x) - (BUS_OFFSET - PAGE_OFFSET))
-
 /*
  * Cache flushing area.
  */
-- 
2.29.2

Re: [PATCH 5/4] ARM: footbridge: remove custom DMA address handling

[Russell King (Oracle)]

On Thu, Aug 25, 2022 at 11:17:52AM +0200, Arnd Bergmann wrote:
> From: Arnd Bergmann <arnd@arndb.de>
> 
> Footbridge is the last Arm platform that has its own
> __virt_to_bus()/__bus_to_virt()/phys_to_dma()/dma_to_phys() abstraction,
> but this is just a simple offset now.
> 
> For ISA DMA (floppy etc), the offset is actually zero, so the special
> hack to subtract the bus offset can be removed from common code.

No, the offset is definitely not zero for ISA devices. ISA devices have
the same view of system memory as PCI devices, since ISA devices go
through a southbridge and on to the PCI bus. So their view of the system
is exactly the same as any other PCI device.

-- 
RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
FTTP is here! 40Mbps down 10Mbps up. Decent connectivity at last!

Re: [PATCH 5/4] ARM: footbridge: remove custom DMA address handling

[Russell King (Oracle)]

On Thu, Aug 25, 2022 at 11:17:52AM +0200, Arnd Bergmann wrote:
> -/*
> - * The footbridge is programmed to expose the system RAM at 0xe0000000.
> - * The requirement is that the RAM isn't placed at bus address 0, which
> - * would clash with VGA cards.
> - */
> -#define BUS_OFFSET		0xe0000000
> -#define __virt_to_bus(x)	((x) + (BUS_OFFSET - PAGE_OFFSET))
> -#define __bus_to_virt(x)	((x) - (BUS_OFFSET - PAGE_OFFSET))

... and this tells you why that is with ISA devices.

So, one hell of a big NAK to this patch, sorry.

-- 
RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
FTTP is here! 40Mbps down 10Mbps up. Decent connectivity at last!

Re: [PATCH 5/4] ARM: footbridge: remove custom DMA address handling

[Arnd Bergmann]

On Thu, Aug 25, 2022 at 12:35 PM Russell King (Oracle)
<linux@armlinux.org.uk> wrote:
>
> On Thu, Aug 25, 2022 at 11:17:52AM +0200, Arnd Bergmann wrote:
> > -/*
> > - * The footbridge is programmed to expose the system RAM at 0xe0000000.
> > - * The requirement is that the RAM isn't placed at bus address 0, which
> > - * would clash with VGA cards.
> > - */
> > -#define BUS_OFFSET           0xe0000000
> > -#define __virt_to_bus(x)     ((x) + (BUS_OFFSET - PAGE_OFFSET))
> > -#define __bus_to_virt(x)     ((x) - (BUS_OFFSET - PAGE_OFFSET))
>
> ... and this tells you why that is with ISA devices.
>
> So, one hell of a big NAK to this patch, sorry.

Thanks for taking a look. Apparently I misread the interface, and I assumed
that the __bus_to_virt() BUS_OFFSET in set_dma_addr() would
just cancel out the dma_map_single() in isa_enable_dma().

It turns out the logic is actually simpler and we just convert between
virtual address and bus address three times. for most drivers.

I found one driver (cs89x0-isa) that uses isa_virt_to_bus()/virt_to_phys()
instead of dma_map_single(), but that is probably never used here.
Once we move the DMA offset into the device, all other ISA devices will
also get the default zero-offset, but I think that will be fine as long as the
"isa_dma_dev" that is used for the final translation has the correct offset.

I'll try to come up with a new version tomorrow.

       Arnd

[PATCH v2 5/4] ARM: footbridge: remove custom DMA address handling

[Arnd Bergmann]

From: Arnd Bergmann <arnd@arndb.de>

Footbridge is the last Arm platform that has its own
__virt_to_bus()/__bus_to_virt()/phys_to_dma()/dma_to_phys() abstraction,
but this is just a simple offset now.

For PCI devices, the offset that is programmed into the PCI bridge must
also be set in each device using dma_direct_set_offset().  As Arm does
not have a pcibios_bus_add_device() helper yet, just use a bus notifier
for this.

For the ISA DMA, drivers now pass a non-translated physical address into
set_dma_addr(), so they have to be converted back with the corresponding
isa_bus_to_virt() function and then into the correct bus address with
the offset using the isa_dma_dev.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
---
v2: fix ISA DMA offset

 arch/arm/include/asm/dma-direct.h             |  1 -
 arch/arm/include/asm/dma.h                    |  2 +-
 arch/arm/include/asm/hardware/dec21285.h      |  7 +++++++
 arch/arm/include/asm/memory.h                 | 11 ----------
 arch/arm/mach-footbridge/Kconfig              |  1 -
 arch/arm/mach-footbridge/common.c             | 10 ---------
 arch/arm/mach-footbridge/dc21285.c            | 21 ++++++++++++++++++-
 arch/arm/mach-footbridge/dma-isa.c            |  4 ++++
 .../mach-footbridge/include/mach/dma-direct.h |  8 -------
 .../arm/mach-footbridge/include/mach/memory.h |  9 --------
 10 files changed, 32 insertions(+), 42 deletions(-)
 delete mode 100644 arch/arm/include/asm/dma-direct.h
 delete mode 100644 arch/arm/mach-footbridge/include/mach/dma-direct.h

diff --git a/arch/arm/include/asm/dma-direct.h b/arch/arm/include/asm/dma-direct.h
deleted file mode 100644
index 4f7bcde03abb..000000000000
--- a/arch/arm/include/asm/dma-direct.h
+++ /dev/null
@@ -1 +0,0 @@
-#include <mach/dma-direct.h>
diff --git a/arch/arm/include/asm/dma.h b/arch/arm/include/asm/dma.h
index 05f29a72150b..c6aded1b069c 100644
--- a/arch/arm/include/asm/dma.h
+++ b/arch/arm/include/asm/dma.h
@@ -106,7 +106,7 @@ extern void set_dma_sg(unsigned int chan, struct scatterlist *sg, int nr_sg);
  */
 extern void __set_dma_addr(unsigned int chan, void *addr);
 #define set_dma_addr(chan, addr)				\
-	__set_dma_addr(chan, (void *)__bus_to_virt(addr))
+	__set_dma_addr(chan, (void *)isa_bus_to_virt(addr))
 
 /* Set the DMA byte count for this channel
  *
diff --git a/arch/arm/include/asm/hardware/dec21285.h b/arch/arm/include/asm/hardware/dec21285.h
index eee390e8d4dc..894f2a635cbb 100644
--- a/arch/arm/include/asm/hardware/dec21285.h
+++ b/arch/arm/include/asm/hardware/dec21285.h
@@ -22,6 +22,13 @@
 #define DC21285_IO(x)		(x)
 #endif
 
+/*
+ * The footbridge is programmed to expose the system RAM at 0xe0000000.
+ * The requirement is that the RAM isn't placed at bus address 0, which
+ * would clash with VGA cards.
+ */
+#define BUS_OFFSET 0xe0000000
+
 #define CSR_PCICMD		DC21285_IO(0x0004)
 #define CSR_CLASSREV		DC21285_IO(0x0008)
 #define CSR_PCICACHELINESIZE	DC21285_IO(0x000c)
diff --git a/arch/arm/include/asm/memory.h b/arch/arm/include/asm/memory.h
index a55a9038abc8..d8eef4bd8c71 100644
--- a/arch/arm/include/asm/memory.h
+++ b/arch/arm/include/asm/memory.h
@@ -369,17 +369,6 @@ static inline unsigned long __virt_to_idmap(unsigned long x)
 
 #define virt_to_idmap(x)	__virt_to_idmap((unsigned long)(x))
 
-/*
- * Virtual <-> DMA view memory address translations
- * Again, these are *only* valid on the kernel direct mapped RAM
- * memory.  Use of these is *deprecated* (and that doesn't mean
- * use the __ prefixed forms instead.)  See dma-mapping.h.
- */
-#ifndef __virt_to_bus
-#define __virt_to_bus	__virt_to_phys
-#define __bus_to_virt	__phys_to_virt
-#endif
-
 /*
  * Conversion between a struct page and a physical address.
  *
diff --git a/arch/arm/mach-footbridge/Kconfig b/arch/arm/mach-footbridge/Kconfig
index cd18871fd03f..f452663576d1 100644
--- a/arch/arm/mach-footbridge/Kconfig
+++ b/arch/arm/mach-footbridge/Kconfig
@@ -44,7 +44,6 @@ endmenu
 # Footbridge support
 config FOOTBRIDGE
 	def_bool y
-	select ARCH_HAS_PHYS_TO_DMA
 	select ARCH_MIGHT_HAVE_PC_SERIO
 	select ISA_DMA_API
 
diff --git a/arch/arm/mach-footbridge/common.c b/arch/arm/mach-footbridge/common.c
index 9483eccea5ae..629e4676ed77 100644
--- a/arch/arm/mach-footbridge/common.c
+++ b/arch/arm/mach-footbridge/common.c
@@ -281,13 +281,3 @@ void footbridge_restart(enum reboot_mode mode, const char *cmd)
 		*CSR_SA110_CNTL |= (1 << 13);
 	}
 }
-
-dma_addr_t phys_to_dma(struct device *dev, phys_addr_t paddr)
-{
-	return paddr + (BUS_OFFSET - PHYS_OFFSET);
-}
-
-phys_addr_t dma_to_phys(struct device *dev, dma_addr_t dev_addr)
-{
-	return dev_addr - (BUS_OFFSET - PHYS_OFFSET);
-}
diff --git a/arch/arm/mach-footbridge/dc21285.c b/arch/arm/mach-footbridge/dc21285.c
index 372600bc15c8..f8920d0010de 100644
--- a/arch/arm/mach-footbridge/dc21285.c
+++ b/arch/arm/mach-footbridge/dc21285.c
@@ -5,6 +5,7 @@
  *  Copyright (C) 1998-2001 Russell King
  *  Copyright (C) 1998-2000 Phil Blundell
  */
+#include <linux/dma-map-ops.h>
 #include <linux/kernel.h>
 #include <linux/pci.h>
 #include <linux/interrupt.h>
@@ -241,6 +242,22 @@ static irqreturn_t dc21285_parity_irq(int irq, void *dev_id)
 	return IRQ_HANDLED;
 }
 
+static int dc21285_pci_bus_notifier(struct notifier_block *nb,
+				    unsigned long action,
+				    void *data)
+{
+	if (action != BUS_NOTIFY_ADD_DEVICE)
+		return NOTIFY_DONE;
+
+	dma_direct_set_offset(data, PHYS_OFFSET, BUS_OFFSET, SZ_256M);
+
+	return NOTIFY_OK;
+}
+
+static struct notifier_block dc21285_pci_bus_nb = {
+	.notifier_call = dc21285_pci_bus_notifier,
+};
+
 int __init dc21285_setup(int nr, struct pci_sys_data *sys)
 {
 	struct resource *res;
@@ -266,6 +283,8 @@ int __init dc21285_setup(int nr, struct pci_sys_data *sys)
 	pci_add_resource_offset(&sys->resources, &res[0], sys->mem_offset);
 	pci_add_resource_offset(&sys->resources, &res[1], sys->mem_offset);
 
+	bus_register_notifier(&pci_bus_type, &dc21285_pci_bus_nb);
+
 	return 1;
 }
 
@@ -329,7 +348,7 @@ void __init dc21285_preinit(void)
 	 */
 	*CSR_PCICSRBASE       = 0xf4000000;
 	*CSR_PCICSRIOBASE     = 0;
-	*CSR_PCISDRAMBASE     = __virt_to_bus(PAGE_OFFSET);
+	*CSR_PCISDRAMBASE     = BUS_OFFSET;
 	*CSR_PCIROMBASE       = 0;
 	*CSR_PCICMD = PCI_COMMAND_MEMORY | PCI_COMMAND_MASTER |
 		      PCI_COMMAND_INVALIDATE | PCICMD_ERROR_BITS;
diff --git a/arch/arm/mach-footbridge/dma-isa.c b/arch/arm/mach-footbridge/dma-isa.c
index 0fc0705fd58b..937f5376d5e7 100644
--- a/arch/arm/mach-footbridge/dma-isa.c
+++ b/arch/arm/mach-footbridge/dma-isa.c
@@ -11,6 +11,7 @@
  *   arch/arm/kernel/dma-ebsa285.c
  *   Copyright (C) 1998 Phil Blundell
  */
+#include <linux/dma-map-ops.h>
 #include <linux/ioport.h>
 #include <linux/init.h>
 #include <linux/dma-mapping.h>
@@ -18,6 +19,7 @@
 
 #include <asm/dma.h>
 #include <asm/mach/dma.h>
+#include <asm/hardware/dec21285.h>
 
 #define ISA_DMA_MASK		0
 #define ISA_DMA_MODE		1
@@ -221,6 +223,8 @@ static int __init isa_dma_init(void)
 		request_dma(DMA_ISA_CASCADE, "cascade");
 	}
 
+	dma_direct_set_offset(&isa_dma_dev, PHYS_OFFSET, BUS_OFFSET, SZ_256M);
+
 	return 0;
 }
 core_initcall(isa_dma_init);
diff --git a/arch/arm/mach-footbridge/include/mach/dma-direct.h b/arch/arm/mach-footbridge/include/mach/dma-direct.h
deleted file mode 100644
index 01f9e8367c00..000000000000
--- a/arch/arm/mach-footbridge/include/mach/dma-direct.h
+++ /dev/null
@@ -1,8 +0,0 @@
-/* SPDX-License-Identifier: GPL-2.0 */
-#ifndef MACH_FOOTBRIDGE_DMA_DIRECT_H
-#define MACH_FOOTBRIDGE_DMA_DIRECT_H 1
-
-dma_addr_t phys_to_dma(struct device *dev, phys_addr_t paddr);
-phys_addr_t dma_to_phys(struct device *dev, dma_addr_t dev_addr);
-
-#endif /* MACH_FOOTBRIDGE_DMA_DIRECT_H */
diff --git a/arch/arm/mach-footbridge/include/mach/memory.h b/arch/arm/mach-footbridge/include/mach/memory.h
index 8f0ca8e8b37e..9516877667d7 100644
--- a/arch/arm/mach-footbridge/include/mach/memory.h
+++ b/arch/arm/mach-footbridge/include/mach/memory.h
@@ -16,15 +16,6 @@
 #ifndef __ASM_ARCH_MEMORY_H
 #define __ASM_ARCH_MEMORY_H
 
-/*
- * The footbridge is programmed to expose the system RAM at 0xe0000000.
- * The requirement is that the RAM isn't placed at bus address 0, which
- * would clash with VGA cards.
- */
-#define BUS_OFFSET		0xe0000000
-#define __virt_to_bus(x)	((x) + (BUS_OFFSET - PAGE_OFFSET))
-#define __bus_to_virt(x)	((x) - (BUS_OFFSET - PAGE_OFFSET))
-
 /*
  * Cache flushing area.
  */
-- 
2.29.2

Re: [PATCH v2 5/4] ARM: footbridge: remove custom DMA address handling

[Robin Murphy]

On 2022-08-25 21:15, Arnd Bergmann wrote:
[...]
> diff --git a/arch/arm/mach-footbridge/dc21285.c b/arch/arm/mach-footbridge/dc21285.c
> index 372600bc15c8..f8920d0010de 100644
> --- a/arch/arm/mach-footbridge/dc21285.c
> +++ b/arch/arm/mach-footbridge/dc21285.c
> @@ -5,6 +5,7 @@
>    *  Copyright (C) 1998-2001 Russell King
>    *  Copyright (C) 1998-2000 Phil Blundell
>    */
> +#include <linux/dma-map-ops.h>
>   #include <linux/kernel.h>
>   #include <linux/pci.h>
>   #include <linux/interrupt.h>
> @@ -241,6 +242,22 @@ static irqreturn_t dc21285_parity_irq(int irq, void *dev_id)
>   	return IRQ_HANDLED;
>   }
>   
> +static int dc21285_pci_bus_notifier(struct notifier_block *nb,
> +				    unsigned long action,
> +				    void *data)
> +{
> +	if (action != BUS_NOTIFY_ADD_DEVICE)
> +		return NOTIFY_DONE;
> +
> +	dma_direct_set_offset(data, PHYS_OFFSET, BUS_OFFSET, SZ_256M);

FWIW I've always had it in mind that for this kind of special case the 
platform could just statically allocate the dma_range_map and assign it 
to all devices. However in practice that needs some kfree_const() tweaks 
in the driver core, which I'm sure are out-of-scope for this series, so 
I'm mostly flagging this up to help myself remember that it might be 
worth doing a dma_direct_set_offset() cleanup sweep soon.

As-is the patch at least makes things a lot clearer, and presumably 
there aren't likely to be enough PCI devices for the extra allocations 
to have noticeable impact in the meantime.

Cheers,
Robin.

Re: [PATCH 0/4] ARM: footbridge: cleanups

[Marc Zyngier]

On Thu, 18 Aug 2022 22:15:46 +0100,
Arnd Bergmann <arnd@kernel.org> wrote:
> 
> From: Arnd Bergmann <arnd@arndb.de>
> 
> I had an older patch to remove the addin mode for footbridge,
> which nobody is using any more, and I found a few other small
> cleanups that are worth doing here.
> 
> Footbridge is now the only platform with a custom __virt_to_bus()
> for ISA DMA, and a custom phys_to_dma() for PCI devices. Both
> just add a fixed offset, so there is probably a better way
> of doing the same without a custom helper function.
> 
>      Arnd
> 
> Arnd Bergmann (4):
>   ARM: footbridge: remove addin mode
>   ARM: footbridge: remove leftover from personal-server
>   ARM: footbridge: move isa-dma support into footbridge
>   ARM: footbridge: limit CONFIG_ISA to CATS
> 
>  arch/arm/Kconfig                              |  5 --
>  arch/arm/include/asm/hardware/dec21285.h      | 13 ----
>  arch/arm/kernel/Makefile                      |  1 -
>  arch/arm/mach-footbridge/Kconfig              | 30 +-------
>  arch/arm/mach-footbridge/Makefile             |  5 +-
>  arch/arm/mach-footbridge/common.c             | 73 ++-----------------
>  arch/arm/mach-footbridge/dc21285.c            | 61 +++++-----------
>  .../arm/{kernel => mach-footbridge}/dma-isa.c |  7 +-
>  arch/arm/mach-footbridge/dma.c                | 58 ---------------
>  .../mach-footbridge/include/mach/isa-dma.h    | 14 +---
>  .../arm/mach-footbridge/include/mach/memory.h | 22 ------
>  arch/arm/mach-footbridge/isa.c                | 14 ++--
>  drivers/tty/serial/21285.c                    |  3 -
>  13 files changed, 42 insertions(+), 264 deletions(-)
>  rename arch/arm/{kernel => mach-footbridge}/dma-isa.c (98%)
>  delete mode 100644 arch/arm/mach-footbridge/dma.c
> 
> -- 
> 2.29.2
> 
> Cc: Russell King <linux@armlinux.org.uk>
> Cc: Christoph Hellwig <hch@lst.de>
> Cc: Linus Walleij <linus.walleij@linaro.org>
> Cc: Marc Zyngier <maz@kernel.org>

I finally managed to give this a go on my netwinder using v2 of patch
5/4 (!), and the box booted nicely.

Note that apart from the serial console, everything I'm using on this
box is PCI (I tried to enable sound and failed, probably because I
can't select CONFIG_ISA anymore on this machine).

Anyway, for the purpose of this series:

Tested-by: Marc Zyngier <maz@kernel.org>

	   M.

-- 
Without deviation from the norm, progress is not possible.

Re: [PATCH 0/4] ARM: footbridge: cleanups

[Russell King (Oracle)]

On Sun, Sep 04, 2022 at 12:43:48PM +0100, Marc Zyngier wrote:
> On Thu, 18 Aug 2022 22:15:46 +0100,
> Arnd Bergmann <arnd@kernel.org> wrote:
> > 
> > From: Arnd Bergmann <arnd@arndb.de>
> > 
> > I had an older patch to remove the addin mode for footbridge,
> > which nobody is using any more, and I found a few other small
> > cleanups that are worth doing here.
> > 
> > Footbridge is now the only platform with a custom __virt_to_bus()
> > for ISA DMA, and a custom phys_to_dma() for PCI devices. Both
> > just add a fixed offset, so there is probably a better way
> > of doing the same without a custom helper function.
> > 
> >      Arnd
> > 
> > Arnd Bergmann (4):
> >   ARM: footbridge: remove addin mode
> >   ARM: footbridge: remove leftover from personal-server
> >   ARM: footbridge: move isa-dma support into footbridge
> >   ARM: footbridge: limit CONFIG_ISA to CATS
> > 
> >  arch/arm/Kconfig                              |  5 --
> >  arch/arm/include/asm/hardware/dec21285.h      | 13 ----
> >  arch/arm/kernel/Makefile                      |  1 -
> >  arch/arm/mach-footbridge/Kconfig              | 30 +-------
> >  arch/arm/mach-footbridge/Makefile             |  5 +-
> >  arch/arm/mach-footbridge/common.c             | 73 ++-----------------
> >  arch/arm/mach-footbridge/dc21285.c            | 61 +++++-----------
> >  .../arm/{kernel => mach-footbridge}/dma-isa.c |  7 +-
> >  arch/arm/mach-footbridge/dma.c                | 58 ---------------
> >  .../mach-footbridge/include/mach/isa-dma.h    | 14 +---
> >  .../arm/mach-footbridge/include/mach/memory.h | 22 ------
> >  arch/arm/mach-footbridge/isa.c                | 14 ++--
> >  drivers/tty/serial/21285.c                    |  3 -
> >  13 files changed, 42 insertions(+), 264 deletions(-)
> >  rename arch/arm/{kernel => mach-footbridge}/dma-isa.c (98%)
> >  delete mode 100644 arch/arm/mach-footbridge/dma.c
> > 
> > -- 
> > 2.29.2
> > 
> > Cc: Russell King <linux@armlinux.org.uk>
> > Cc: Christoph Hellwig <hch@lst.de>
> > Cc: Linus Walleij <linus.walleij@linaro.org>
> > Cc: Marc Zyngier <maz@kernel.org>
> 
> I finally managed to give this a go on my netwinder using v2 of patch
> 5/4 (!), and the box booted nicely.
> 
> Note that apart from the serial console, everything I'm using on this
> box is PCI (I tried to enable sound and failed, probably because I
> can't select CONFIG_ISA anymore on this machine).

That tends to mean, therefore, that the statement "CONFIG_ISA is for
add-in cards" is wrong, because it's caused a user-visible regression
by killing sound support on Netwinders!

-- 
RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
FTTP is here! 40Mbps down 10Mbps up. Decent connectivity at last!

Re: [PATCH 0/4] ARM: footbridge: cleanups

[Marc Zyngier]

On Sun, 04 Sep 2022 13:09:42 +0100,
"Russell King (Oracle)" <linux@armlinux.org.uk> wrote:
> 
> On Sun, Sep 04, 2022 at 12:43:48PM +0100, Marc Zyngier wrote:
> > On Thu, 18 Aug 2022 22:15:46 +0100,
> > Arnd Bergmann <arnd@kernel.org> wrote:
> > > 
> > > From: Arnd Bergmann <arnd@arndb.de>
> > > 
> > > I had an older patch to remove the addin mode for footbridge,
> > > which nobody is using any more, and I found a few other small
> > > cleanups that are worth doing here.
> > > 
> > > Footbridge is now the only platform with a custom __virt_to_bus()
> > > for ISA DMA, and a custom phys_to_dma() for PCI devices. Both
> > > just add a fixed offset, so there is probably a better way
> > > of doing the same without a custom helper function.
> > > 
> > >      Arnd
> > > 
> > > Arnd Bergmann (4):
> > >   ARM: footbridge: remove addin mode
> > >   ARM: footbridge: remove leftover from personal-server
> > >   ARM: footbridge: move isa-dma support into footbridge
> > >   ARM: footbridge: limit CONFIG_ISA to CATS
> > > 
> > >  arch/arm/Kconfig                              |  5 --
> > >  arch/arm/include/asm/hardware/dec21285.h      | 13 ----
> > >  arch/arm/kernel/Makefile                      |  1 -
> > >  arch/arm/mach-footbridge/Kconfig              | 30 +-------
> > >  arch/arm/mach-footbridge/Makefile             |  5 +-
> > >  arch/arm/mach-footbridge/common.c             | 73 ++-----------------
> > >  arch/arm/mach-footbridge/dc21285.c            | 61 +++++-----------
> > >  .../arm/{kernel => mach-footbridge}/dma-isa.c |  7 +-
> > >  arch/arm/mach-footbridge/dma.c                | 58 ---------------
> > >  .../mach-footbridge/include/mach/isa-dma.h    | 14 +---
> > >  .../arm/mach-footbridge/include/mach/memory.h | 22 ------
> > >  arch/arm/mach-footbridge/isa.c                | 14 ++--
> > >  drivers/tty/serial/21285.c                    |  3 -
> > >  13 files changed, 42 insertions(+), 264 deletions(-)
> > >  rename arch/arm/{kernel => mach-footbridge}/dma-isa.c (98%)
> > >  delete mode 100644 arch/arm/mach-footbridge/dma.c
> > > 
> > > -- 
> > > 2.29.2
> > > 
> > > Cc: Russell King <linux@armlinux.org.uk>
> > > Cc: Christoph Hellwig <hch@lst.de>
> > > Cc: Linus Walleij <linus.walleij@linaro.org>
> > > Cc: Marc Zyngier <maz@kernel.org>
> > 
> > I finally managed to give this a go on my netwinder using v2 of patch
> > 5/4 (!), and the box booted nicely.
> > 
> > Note that apart from the serial console, everything I'm using on this
> > box is PCI (I tried to enable sound and failed, probably because I
> > can't select CONFIG_ISA anymore on this machine).
> 
> That tends to mean, therefore, that the statement "CONFIG_ISA is for
> add-in cards" is wrong, because it's caused a user-visible regression
> by killing sound support on Netwinders!

To some extent, yes. Adding this allows me to peek at some of the ISA
soundcards:

diff --git a/arch/arm/mach-footbridge/Kconfig b/arch/arm/mach-footbridge/Kconfig
index f452663576d1..f4c4222fa7c0 100644
--- a/arch/arm/mach-footbridge/Kconfig
+++ b/arch/arm/mach-footbridge/Kconfig
@@ -31,6 +31,7 @@ config ARCH_NETWINDER
 	select CLKEVT_I8253
 	select CLKSRC_I8253
 	select FORCE_PCI
+	select ISA
 	help
 	  Say Y here if you intend to run this kernel on the Rebel.COM
 	  NetWinder.  Information about this machine can be found at:

However, the Waveartist driver has gone the way of the dodo (together
with the rest of the OSS support in 4.15), and it isn't obvious to me
whether one of the several SoundBlaster drivers is appropriate on this
machine.

I also cannot say I deeply care, to be honest.

	M.

-- 
Without deviation from the norm, progress is not possible.

Re: [PATCH 0/4] ARM: footbridge: cleanups

[Arnd Bergmann]

On Sun, Sep 4, 2022, at 6:10 PM, Marc Zyngier wrote:
> On Sun, 04 Sep 2022 13:09:42 +0100,
> "Russell King (Oracle)" <linux@armlinux.org.uk> wrote:
>> > > Cc: Russell King <linux@armlinux.org.uk>
>> > > Cc: Christoph Hellwig <hch@lst.de>
>> > > Cc: Linus Walleij <linus.walleij@linaro.org>
>> > > Cc: Marc Zyngier <maz@kernel.org>
>> > 
>> > I finally managed to give this a go on my netwinder using v2 of patch
>> > 5/4 (!), and the box booted nicely.

Excellent, thanks for testing!

>> > Note that apart from the serial console, everything I'm using on this
>> > box is PCI (I tried to enable sound and failed, probably because I
>> > can't select CONFIG_ISA anymore on this machine).

There are a couple of ISA-style devices on the superIO chip,
and I had checked this one to see what actually uses the
ISA DMA. As far as I can tell, the ECP parallel port and floppy
should still fully work in DMA mode, but these don't depend on
CONFIG_ISA. Irda and waveartist are gone, and the keyboard/mouse,
RTC, uart etc are neither DMA capable not based on CONFIG_ISA.

>> That tends to mean, therefore, that the statement "CONFIG_ISA is for
>> add-in cards" is wrong, because it's caused a user-visible regression
>> by killing sound support on Netwinders!
>
> To some extent, yes. Adding this allows me to peek at some of the ISA
> soundcards:
>
> diff --git a/arch/arm/mach-footbridge/Kconfig b/arch/arm/mach-footbridge/Kconfig
> index f452663576d1..f4c4222fa7c0 100644
> --- a/arch/arm/mach-footbridge/Kconfig
> +++ b/arch/arm/mach-footbridge/Kconfig
> @@ -31,6 +31,7 @@ config ARCH_NETWINDER
>  	select CLKEVT_I8253
>  	select CLKSRC_I8253
>  	select FORCE_PCI
> +	select ISA
>  	help
>  	  Say Y here if you intend to run this kernel on the Rebel.COM
>  	  NetWinder.  Information about this machine can be found at:
>
> However, the Waveartist driver has gone the way of the dodo (together
> with the rest of the OSS support in 4.15), and it isn't obvious to me
> whether one of the several SoundBlaster drivers is appropriate on this
> machine.
>
> I also cannot say I deeply care, to be honest.

I already made sure that there are no devices in the defconfig
that get disabled when turning off CONFIG_ISA, so at least for
anyone using the defconfig, my change made no difference.

It's possible that the sb16 ISA driver works in non-PNP mode,
but it appears to look for the wrong IRQ number and mixer,
the other SB16 compatible drivers all assume ISAPNP or PCI.

My guess is that to use this properly, one would have
to turn take the mixer bits from the OSS waveartist
driver and turn that into an ALSA driver along with a
simple platform driver frontend for sb16-common.ko.

      Arnd