Subject: Re: [RFC PATCH 09/19] powerpc: gamecube/wii: udbg support for usbgecko

From: Benjamin Herrenschmidt <[email-masked]>
Date: Thu, 26 Nov 2009 16:12:34 +1100

On Sun, 2009-11-22 at 23:01 +0100, Albert Herranz wrote:
> Add support for using the USB Gecko adapter via the udbg facility on
> the Nintendo GameCube and Wii video game consoles.
> The USB Gecko is a 3rd party memory card interface adapter that provides
> a EXI (External Interface) to USB serial converter.

The main issue here is that the gecko is supposed to be something you
can plug or unplug no ? Is it hotswap or only at boot ? In the later
case, maybe the node should be created by the boot wrapper when
detecting the presence of the device. If it's hotplug, then we need
something smarter...

Cheers,
Ben.

> Signed-off-by: Albert Herranz <[email-masked]>
> ---
>  arch/powerpc/platforms/embedded6xx/Kconfig         |   13 +
>  arch/powerpc/platforms/embedded6xx/Makefile        |    1 +
>  arch/powerpc/platforms/embedded6xx/usbgecko_udbg.c |  285 ++++++++++++++++++++
>  arch/powerpc/platforms/embedded6xx/usbgecko_udbg.h |   30 ++
>  4 files changed, 329 insertions(+), 0 deletions(-)
>  create mode 100644 arch/powerpc/platforms/embedded6xx/usbgecko_udbg.c
>  create mode 100644 arch/powerpc/platforms/embedded6xx/usbgecko_udbg.h
> 
> diff --git a/arch/powerpc/platforms/embedded6xx/Kconfig b/arch/powerpc/platforms/embedded6xx/Kconfig
> index 31487e4..bfd88be 100644
> --- a/arch/powerpc/platforms/embedded6xx/Kconfig
> +++ b/arch/powerpc/platforms/embedded6xx/Kconfig
> @@ -95,3 +95,16 @@ config GAMECUBE_COMMON
>  	bool
>  	select NOT_COHERENT_CACHE
>  
> +config USBGECKO_UDBG
> +	bool "USB Gecko udbg console for the Nintendo GameCube/Wii"
> +	depends on GAMECUBE_COMMON
> +	help
> +	  If you say yes to this option, support will be included for the
> +	  USB Gecko adapter as an udbg console.
> +	  The USB Gecko is a EXI to USB Serial converter that can be plugged
> +	  into a memcard slot in the Nintendo GameCube/Wii.
> +
> +	  This driver bypasses the EXI layer completely.
> +
> +	  If in doubt, say N here.
> +
> diff --git a/arch/powerpc/platforms/embedded6xx/Makefile b/arch/powerpc/platforms/embedded6xx/Makefile
> index 0773c08..0ab7492 100644
> --- a/arch/powerpc/platforms/embedded6xx/Makefile
> +++ b/arch/powerpc/platforms/embedded6xx/Makefile
> @@ -7,3 +7,4 @@ obj-$(CONFIG_STORCENTER)	+= storcenter.o
>  obj-$(CONFIG_PPC_HOLLY)		+= holly.o
>  obj-$(CONFIG_PPC_PRPMC2800)	+= prpmc2800.o
>  obj-$(CONFIG_PPC_C2K)		+= c2k.o
> +obj-$(CONFIG_USBGECKO_UDBG)	+= usbgecko_udbg.o
> diff --git a/arch/powerpc/platforms/embedded6xx/usbgecko_udbg.c b/arch/powerpc/platforms/embedded6xx/usbgecko_udbg.c
> new file mode 100644
> index 0000000..49f86e8
> --- /dev/null
> +++ b/arch/powerpc/platforms/embedded6xx/usbgecko_udbg.c
> @@ -0,0 +1,285 @@
> +/*
> + * arch/powerpc/platforms/embedded6xx/usbgecko_udbg.c
> + *
> + * udbg serial input/output routines for the USB Gecko adapter.
> + * Copyright (C) 2008-2009 The GameCube Linux Team
> + * Copyright (C) 2008,2009 Albert Herranz
> + *
> + * This program is free software; you can redistribute it and/or
> + * modify it under the terms of the GNU General Public License
> + * as published by the Free Software Foundation; either version 2
> + * of the License, or (at your option) any later version.
> + *
> + */
> +
> +#include <asm/io.h>
> +#include <asm/prom.h>
> +#include <asm/udbg.h>
> +
> +#include <mm/mmu_decl.h>
> +
> +#include "usbgecko_udbg.h"
> +
> +
> +#define EXI_CLK_32MHZ           5
> +
> +#define EXI_CSR                 0x00
> +#define   EXI_CSR_CLKMASK       (0x7<<4)
> +#define     EXI_CSR_CLK_32MHZ   (EXI_CLK_32MHZ<<4)
> +#define   EXI_CSR_CSMASK        (0x7<<7)
> +#define     EXI_CSR_CS_0        (0x1<<7)  /* Chip Select 001 */
> +
> +#define EXI_CR                  0x0c
> +#define   EXI_CR_TSTART         (1<<0)
> +#define   EXI_CR_WRITE		(1<<2)
> +#define   EXI_CR_READ_WRITE     (2<<2)
> +#define   EXI_CR_TLEN(len)      (((len)-1)<<4)
> +
> +#define EXI_DATA                0x10
> +
> +#define UG_READ_ATTEMPTS	100
> +#define UG_WRITE_ATTEMPTS	100
> +
> +
> +static void __iomem *ug_io_base;
> +
> +/*
> + * Performs one input/output transaction between the exi host and the usbgecko.
> + */
> +static u32 ug_io_transaction(u32 in)
> +{
> +	u32 __iomem *csr_reg = ug_io_base + EXI_CSR;
> +	u32 __iomem *data_reg = ug_io_base + EXI_DATA;
> +	u32 __iomem *cr_reg = ug_io_base + EXI_CR;
> +	u32 csr, data, cr;
> +
> +	/* select */
> +	csr = EXI_CSR_CLK_32MHZ | EXI_CSR_CS_0;
> +	out_be32(csr_reg, csr);
> +
> +	/* read/write */
> +	data = in;
> +	out_be32(data_reg, data);
> +	cr = EXI_CR_TLEN(2) | EXI_CR_READ_WRITE | EXI_CR_TSTART;
> +	out_be32(cr_reg, cr);
> +
> +	while (in_be32(cr_reg) & EXI_CR_TSTART)
> +		barrier();
> +
> +	/* deselect */
> +	out_be32(csr_reg, 0);
> +
> +	/* result */
> +	data = in_be32(data_reg);
> +
> +	return data;
> +}
> +
> +/*
> + * Returns true if an usbgecko adapter is found.
> + */
> +static int ug_is_adapter_present(void)
> +{
> +	if (!ug_io_base)
> +		return 0;
> +
> +	return ug_io_transaction(0x90000000) == 0x04700000;
> +}
> +
> +/*
> + * Returns true if the TX fifo is ready for transmission.
> + */
> +static int ug_is_txfifo_ready(void)
> +{
> +	return ug_io_transaction(0xc0000000) & 0x04000000;
> +}
> +
> +/*
> + * Tries to transmit a character.
> + * If the TX fifo is not ready the result is undefined.
> + */
> +static void ug_raw_putc(char ch)
> +{
> +	ug_io_transaction(0xb0000000 | (ch << 20));
> +}
> +
> +/*
> + * Transmits a character.
> + * It silently fails if the TX fifo is not ready after a number of retries.
> + */
> +static void ug_putc(char ch)
> +{
> +	int count = UG_WRITE_ATTEMPTS;
> +
> +	if (!ug_io_base)
> +		return;
> +
> +	if (ch == '\n')
> +		ug_putc('\r');
> +
> +	while (!ug_is_txfifo_ready() && count--)
> +		barrier();
> +	if (count)
> +		ug_raw_putc(ch);
> +}
> +
> +#if 0
> +/*
> + * Trasmits a null terminated character string.
> + */
> +static void ug_puts(char *s)
> +{
> +	while (*s)
> +		ug_putc(*s++);
> +}
> +#endif
> +
> +/*
> + * Returns true if the RX fifo is ready for transmission.
> + */
> +static int ug_is_rxfifo_ready(void)
> +{
> +	return ug_io_transaction(0xd0000000) & 0x04000000;
> +}
> +
> +/*
> + * Tries to receive a character.
> + * If a character is unavailable the function returns -1.
> + */
> +static int ug_raw_getc(void)
> +{
> +	u32 data = ug_io_transaction(0xa0000000);
> +	if (data & 0x08000000)
> +		return (data >> 16) & 0xff;
> +	else
> +		return -1;
> +}
> +
> +/*
> + * Receives a character.
> + * It fails if the RX fifo is not ready after a number of retries.
> + */
> +static int ug_getc(void)
> +{
> +	int count = UG_READ_ATTEMPTS;
> +
> +	if (!ug_io_base)
> +		return -1;
> +
> +	while (!ug_is_rxfifo_ready() && count--)
> +		barrier();
> +	return ug_raw_getc();
> +}
> +
> +/*
> + * udbg functions.
> + *
> + */
> +
> +/*
> + * Transmits a character.
> + */
> +void ug_udbg_putc(char ch)
> +{
> +	ug_putc(ch);
> +}
> +
> +/*
> + * Receives a character. Waits until a character is available.
> + */
> +static int ug_udbg_getc(void)
> +{
> +	int ch;
> +
> +	while ((ch = ug_getc()) == -1)
> +		barrier();
> +	return ch;
> +}
> +
> +/*
> + * Receives a character. If a character is not available, returns -1.
> + */
> +static int ug_udbg_getc_poll(void)
> +{
> +	if (!ug_is_rxfifo_ready())
> +		return -1;
> +	return ug_getc();
> +}
> +
> +/*
> + * Retrieves and prepares the virtual address needed to access the hardware.
> + */
> +static void __iomem *ug_udbg_setup_io_base(struct device_node *np)
> +{
> +	phys_addr_t paddr;
> +	const unsigned int *reg;
> +
> +	reg = of_get_property(np, "reg", NULL);
> +	if (reg) {
> +		paddr = of_translate_address(np, reg);
> +		if (paddr) {
> +			ug_io_base = ioremap(paddr, reg[1]);
> +			return ug_io_base;
> +		}
> +	}
> +	return NULL;
> +}
> +
> +/*
> + * USB Gecko udbg support initialization.
> + */
> +void __init ug_udbg_init(void)
> +{
> +	struct device_node *np = NULL;
> +	struct device_node *stdout;
> +	const char *path;
> +
> +	if (!of_chosen) {
> +		udbg_printf("%s: missing of_chosen\n", __func__);
> +		goto done;
> +	}
> +
> +	path = of_get_property(of_chosen, "linux,stdout-path", NULL);
> +	if (!path) {
> +		udbg_printf("%s: missing %s property", __func__,
> +			    "linux,stdout-path");
> +		goto done;
> +	}
> +
> +	stdout = of_find_node_by_path(path);
> +	if (!stdout) {
> +		udbg_printf("%s: missing path %s", __func__, path);
> +		goto done;
> +	}
> +
> +	for (np = NULL;
> +	    (np = of_find_compatible_node(np, NULL, "usbgecko,usbgecko"));)
> +		if (np == stdout)
> +			break;
> +
> +	of_node_put(stdout);
> +	if (!np) {
> +		udbg_printf("%s: stdout is not an usbgecko", __func__);
> +		goto done;
> +	}
> +
> +	if (!ug_udbg_setup_io_base(np)) {
> +		udbg_printf("%s: failed to setup io base", __func__);
> +		goto done;
> +	}
> +
> +	if (!ug_is_adapter_present()) {
> +		udbg_printf("usbgecko_udbg: not found\n");
> +		ug_io_base = NULL;
> +	} else {
> +		udbg_putc = ug_udbg_putc;
> +		udbg_getc = ug_udbg_getc;
> +		udbg_getc_poll = ug_udbg_getc_poll;
> +		udbg_printf("usbgecko_udbg: ready\n");
> +	}
> +
> +done:
> +	if (np)
> +		of_node_put(np);
> +	return;
> +}
> diff --git a/arch/powerpc/platforms/embedded6xx/usbgecko_udbg.h b/arch/powerpc/platforms/embedded6xx/usbgecko_udbg.h
> new file mode 100644
> index 0000000..3929de3
> --- /dev/null
> +++ b/arch/powerpc/platforms/embedded6xx/usbgecko_udbg.h
> @@ -0,0 +1,30 @@
> +/*
> + * arch/powerpc/platforms/embedded6xx/usbgecko_udbg.h
> + *
> + * udbg serial input/output routines for the USB Gecko adapter.
> + * Copyright (C) 2008-2009 The GameCube Linux Team
> + * Copyright (C) 2008,2009 Albert Herranz
> + *
> + * This program is free software; you can redistribute it and/or
> + * modify it under the terms of the GNU General Public License
> + * as published by the Free Software Foundation; either version 2
> + * of the License, or (at your option) any later version.
> + *
> + */
> +
> +#ifndef __USBGECKO_UDBG_H
> +#define __USBGECKO_UDBG_H
> +
> +#ifdef CONFIG_USBGECKO_UDBG
> +
> +extern void __init ug_udbg_init(void);
> +
> +#else
> +
> +static inline void __init ug_udbg_init(void)
> +{
> +}
> +
> +#endif /* CONFIG_USBGECKO_UDBG */
> +
> +#endif /* __USBGECKO_UDBG_H */