powerpc: gamecube/wii: udbg support for usbgecko

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.

Signed-off-by: Albert Herranz <[e-mail]>
Acked-by: Segher Boessenkool <[e-mail]>
Signed-off-by: Grant Likely <[e-mail]>

arch/powerpc/platforms/embedded6xx/Kconfig

···
 config GAMECUBE_COMMON
 	bool
 
+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.
+

arch/powerpc/platforms/embedded6xx/Makefile

···
 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

arch/powerpc/platforms/embedded6xx/usbgecko_udbg.c

···
+/*
+ * 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 <mm/mmu_decl.h>
+
+#include <asm/io.h>
+#include <asm/prom.h>
+#include <asm/udbg.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);
+}
+
+/*
+ * 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_exi_io_base(struct device_node *np)
+{
+	void __iomem *exi_io_base = NULL;
+	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)
+			exi_io_base = ioremap(paddr, reg[1]);
+	}
+	return exi_io_base;
+}
+
+/*
+ * Checks if a USB Gecko adapter is inserted in any memory card slot.
+ */
+static void __iomem *ug_udbg_probe(void __iomem *exi_io_base)
+{
+	int i;
+
+	/* look for a usbgecko on memcard slots A and B */
+	for (i = 0; i < 2; i++) {
+		ug_io_base = exi_io_base + 0x14 * i;
+		if (ug_is_adapter_present())
+			break;
+	}
+	if (i == 2)
+		ug_io_base = NULL;
+	return ug_io_base;
+
+}
+
+/*
+ * USB Gecko udbg support initialization.
+ */
+void __init ug_udbg_init(void)
+{
+	struct device_node *np;
+	void __iomem *exi_io_base;
+
+	if (ug_io_base)
+		udbg_printf("%s: early -> final\n", __func__);
+
+	np = of_find_compatible_node(NULL, NULL, "nintendo,flipper-exi");
+	if (!np) {
+		udbg_printf("%s: EXI node not found\n", __func__);
+		goto done;
+	}
+
+	exi_io_base = ug_udbg_setup_exi_io_base(np);
+	if (!exi_io_base) {
+		udbg_printf("%s: failed to setup EXI io base\n", __func__);
+		goto done;
+	}
+
+	if (!ug_udbg_probe(exi_io_base)) {
+		udbg_printf("usbgecko_udbg: not found\n");
+		iounmap(exi_io_base);
+	} 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;
+}

arch/powerpc/platforms/embedded6xx/usbgecko_udbg.h

···
+/*
+ * 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 */