exynos5250: Implement support to boot with USB A-A firmware upload

This patch implements the basic infrastructure required to use the USB
A-A firmware upload feature on Exynos5 processors with Coreboot. It will
require a corresponding host-side script that activates the feature and
uploads the correct image parts in the correct order to harcoded target
addresses, as described in the comments of alternate_cbfs.c.

Also fixes a bug in the Google Snow mainboard where it would not
correctly initialize the pinmux configuration for the SPI flash bus.
During a normal SPI boot the IROM would already do that for you, but
when booting from USB you have to do it yourself.

Change-Id: I40a39f8f5d1d70b58dbf258015c1653a27097d67
Signed-off-by: Julius Werner <jwerner@chromium.org>
Reviewed-on: https://gerrit.chromium.org/gerrit/64875
Reviewed-by: Stefan Reinauer <reinauer@chromium.org>
Reviewed-by: Hung-Te Lin <hungte@chromium.org>
Commit-Queue: Gabe Black <gabeblack@chromium.org>
Reviewed-on: http://review.coreboot.org/4456
Tested-by: build bot (Jenkins)
Reviewed-by: Patrick Georgi <patrick@georgi-clan.de>

src/arch/armv7/bootblock_simple.c

@@ -55,9 +55,6 @@ void main(void)
 	/*
 	 * Re-enable icache and branch prediction. MMU and dcache will be
 	 * set up later.
-	 *
-	 * Note: If booting from USB, we need to disable branch prediction
-	 * before copying from USB into RAM (FIXME: why?)
 	 */
 	sctlr = read_sctlr();
 	sctlr |= SCTLR_Z | SCTLR_I;

src/cpu/samsung/exynos5250/Makefile.inc

@@ -3,7 +3,7 @@
 # image outside of CBFS
 INTERMEDIATE += exynos5250_add_bl1
 
-bootblock-y += spi.c
+bootblock-y += spi.c alternate_cbfs.c
 bootblock-y += pinmux.c mct.c power.c
 # Clock is required for UART
 bootblock-$(CONFIG_BOOTBLOCK_CONSOLE) += clock_init.c
@@ -16,7 +16,7 @@ bootblock-y += wakeup.c
 bootblock-y += gpio.c
 bootblock-$(CONFIG_BOOTBLOCK_CONSOLE) += timer.c
 
-romstage-y += spi.c
+romstage-y += spi.c alternate_cbfs.c
 romstage-y += clock.c
 romstage-y += clock_init.c
 romstage-y += pinmux.c  # required by s3c24x0_i2c and uart.
@@ -35,7 +35,7 @@ romstage-y += i2c.c
 #romstage-y += wdt.c
 romstage-y += cbmem.c
 
-ramstage-y += spi.c
+ramstage-y += spi.c alternate_cbfs.c
 ramstage-y += clock.c
 ramstage-y += clock_init.c
 ramstage-y += pinmux.c

src/cpu/samsung/exynos5250/alternate_cbfs.c

@@ -0,0 +1,110 @@
+/*
+ * This file is part of the coreboot project.
+ *
+ * Copyright 2013 Google Inc.
+ *
+ * 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; version 2 of the License.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+
+#include <assert.h>
+#include <cbfs.h>  /* This driver serves as a CBFS media source. */
+#include <stdlib.h>
+#include <string.h>
+#include <console/console.h>
+#include "alternate_cbfs.h"
+#include "spi.h"
+
+/* This allows USB A-A firmware upload from a compatible host in four parts:
+ * The first two are the bare BL1 and the Coreboot boot block, which are just
+ * written to their respective loading addresses. These transfers are initiated
+ * by the IROM / BL1, so this code has nothing to do with them.
+ *
+ * The third transfer is a valid CBFS image that contains only the romstage,
+ * and must be small enough to fit into alternate_cbfs_size[__BOOT_BLOCK__] in
+ * IRAM. It is loaded when this function gets called in the boot block, and
+ * the normal CBFS code extracts the romstage from it.
+ *
+ * The fourth transfer is also a CBFS image, but can be of arbitrary size and
+ * should contain all available stages/payloads/etc. It is loaded when this
+ * function is called a second time at the end of the romstage, and copied to
+ * alternate_cbfs_buffer[!__BOOT_BLOCK__] in DRAM. It will reside there for the
+ * rest of the firmware's lifetime and all subsequent stages (which will not
+ * have __PRE_RAM__ defined) can just directly reference it there.
+ */
+static int usb_cbfs_open(struct cbfs_media *media) {
+#ifdef __PRE_RAM__
+	static int first_run = 1;
+	int (*irom_load_usb)(void) = *irom_load_image_from_usb_ptr;
+
+	if (!first_run)
+		return 0;
+
+	if (!irom_load_usb()) {
+		printk(BIOS_ERR, "Unable to load CBFS image via USB!\n");
+		return -1;
+	}
+
+	/*
+	 * We need to trust the host/irom to copy the image to our
+	 * alternate_cbfs_buffer address... there is no way to control or even
+	 * check the transfer size or target address from our side.
+	 */
+
+	printk(BIOS_DEBUG, "USB A-A transfer successful, CBFS image should now"
+		" be at %p\n", alternate_cbfs_buffer);
+	first_run = 0;
+#endif
+	return 0;
+}
+
+static int alternate_cbfs_close(struct cbfs_media *media) { return 0; }
+
+static size_t alternate_cbfs_read(struct cbfs_media *media, void *dest,
+				  size_t offset, size_t count) {
+	ASSERT(offset + count < alternate_cbfs_size);
+	memcpy(dest, alternate_cbfs_buffer + offset, count);
+	return count;
+}
+
+static void *alternate_cbfs_map(struct cbfs_media *media, size_t offset,
+				   size_t count) {
+	ASSERT(offset + count < alternate_cbfs_size);
+	return alternate_cbfs_buffer + offset;
+}
+
+static void *alternate_cbfs_unmap(struct cbfs_media *media,
+				  const void *buffer) { return 0; }
+
+static int initialize_exynos_usb_cbfs_media(struct cbfs_media *media) {
+	printk(BIOS_DEBUG, "Using Exynos alternate boot mode USB A-A\n");
+
+	media->open = usb_cbfs_open;
+	media->close = alternate_cbfs_close;
+	media->read = alternate_cbfs_read;
+	media->map = alternate_cbfs_map;
+	media->unmap = alternate_cbfs_unmap;
+
+	return 0;
+}
+
+int init_default_cbfs_media(struct cbfs_media *media) {
+	if (*iram_secondary_base == SECONDARY_BASE_BOOT_USB)
+		return initialize_exynos_usb_cbfs_media(media);
+
+	/* TODO: implement SDMMC (and possibly other) boot mode */
+
+	return initialize_exynos_spi_cbfs_media(media,
+		(void*)CONFIG_CBFS_CACHE_ADDRESS, CONFIG_CBFS_CACHE_SIZE);
+}

src/cpu/samsung/exynos5250/alternate_cbfs.h

@@ -0,0 +1,44 @@
+/*
+ * This file is part of the coreboot project.
+ *
+ * Copyright 2013 Google Inc.
+ *
+ * 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; version 2 of the License.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+#ifndef CPU_SAMSUNG_EXYNOS5250_ALTERNATE_CBFS_H
+#define CPU_SAMSUNG_EXYNOS5250_ALTERNATE_CBFS_H
+
+/* These are pointers to function pointers. Double indirection! */
+void * * const irom_sdmmc_read_blocks_ptr = (void * *)0x02020030;
+void * * const irom_msh_read_from_fifo_emmc_ptr = (void * *)0x02020044;
+void * * const irom_msh_end_boot_op_emmc_ptr = (void * *)0x02020048;
+void * * const irom_spi_sf_read_ptr = (void * *)0x02020058;
+void * * const irom_load_image_from_usb_ptr = (void * *)0x02020070;
+
+#define SECONDARY_BASE_BOOT_USB 0xfeed0002
+u32 * const iram_secondary_base = (u32 *)0x02020018;
+
+#if defined(__BOOT_BLOCK__)
+	/* A small space in IRAM to hold the romstage-only image */
+	void * const alternate_cbfs_buffer = (void *)CONFIG_CBFS_CACHE_ADDRESS;
+	size_t const alternate_cbfs_size = CONFIG_CBFS_CACHE_SIZE;
+#else
+	/* Just put this anywhere in RAM that's far enough from anything else */
+	/* TODO: Find a better way to "reserve" this region? */
+	void * const alternate_cbfs_buffer = (void *)0x77400000;
+	size_t const alternate_cbfs_size = 0xc00000;
+#endif
+
+#endif

src/cpu/samsung/exynos5250/cpu.h

@@ -26,22 +26,6 @@
 
 #define EXYNOS_PRO_ID			0x10000000
 
-/* Address of address of function that copys data from SD or MMC */
-#define EXYNOS_COPY_MMC_FNPTR_ADDR	0x02020030
-
-/* Address of address of function that copys data from SPI */
-#define EXYNOS_COPY_SPI_FNPTR_ADDR	0x02020058
-
-/* Address of address of function that copys data through USB */
-#define EXYNOS_COPY_USB_FNPTR_ADDR	0x02020070
-
-/* Boot mode values */
-#define EXYNOS_USB_SECONDARY_BOOT	0xfeed0002
-
-#define EXYNOS_IRAM_SECONDARY_BASE	0x02020018
-
-#define EXYNOS_I2C_SPACING		0x10000
-
 /* EXYNOS5 */
 #define EXYNOS5_GPIO_PART6_BASE		0x03860000	/* Z<6:0> */
 #define EXYNOS5_PRO_ID			0x10000000

src/cpu/samsung/exynos5250/pinmux.c

@@ -134,8 +134,11 @@ static void exynos_pinmux_spi(int start, int cfg)
 {
 	int i;
 
-	for (i = 0; i < 4; i++)
+	for (i = 0; i < 4; i++) {
 		gpio_cfg_pin(start + i, GPIO_FUNC(cfg));
+		gpio_set_pull(start + i, GPIO_PULL_NONE);
+		gpio_set_drv(start + i, GPIO_DRV_3X);
+	}
 }
 
 void exynos_pinmux_spi0(void)

src/cpu/samsung/exynos5250/spi.c

@@ -214,10 +214,3 @@ int initialize_exynos_spi_cbfs_media(struct cbfs_media *media,
 
 	return 0;
 }
-
-int init_default_cbfs_media(struct cbfs_media *media) {
-	return initialize_exynos_spi_cbfs_media(
-			media,
-			(void*)CONFIG_CBFS_CACHE_ADDRESS,
-			CONFIG_CBFS_CACHE_SIZE);
-}

src/mainboard/google/snow/romstage.c

@@ -180,7 +180,8 @@ void main(void)
 	setup_gpio();
 	setup_graphics();
 
-	/* Set SPI (primary CBFS media) clock to 50MHz. */
+	/* Set SPI (primary CBFS media) clock to 50MHz and configure pinmux. */
+	exynos_pinmux_spi1();
 	clock_set_rate(PERIPH_ID_SPI1, 50000000);
 
 	cbmem_initialize_empty();