Patchwork NVIDIA Tegra2 SPI controller support

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Submitter David Hendricks
Date 2011-06-27 23:52:04
Message ID <BANLkTikw3GTNGpW5kOirq9MXEn6GRfNVGVX8uD1f+nu6HuC4QA@mail.gmail.com>
Download mbox | patch
Permalink /patch/3219/
State Superseded
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Comments

David Hendricks - 2011-06-27 23:52:04
This patch set makes Flashrom a bit more ARM-friendly and adds raw Tegra2
SPI controller support. It isolates a few PCI-isms, adds some low-level
hardware access stubs, adds Tegra2 processor detection, and adds Tegra2 raw
SPI controller code.

I've attached some logfiles for read/erase/write operations. This particular
patch set was tested using a board based off NVIDIA's Tegra2 reference board
("Seaboard"). Earlier revisions were tested on a Seaboard.

All three attached patches are:
Signed-off-by: David Hendricks <dhendrix@google.com>

Much of the original U-Boot --> Flashrom porting work was done by Stefan
Reinauer <reinauer@google.com>, and the FIFO code updated / fixed up by
Louis Lo <yjlou@google.com>.

A few notes:
1. A few programmers must be disabled due to reliance on PCI. You can hack
up your Makefile or compile with "CONFIG_RAYER_SPI=no CONFIG_NIC3COM=no
CONFIG_NICREALTEK=no CONFIG_SATAMV=no".

2. Due to issues with libpci, you can't use the same binary on machines with
PCI and without PCI. So for example, you can't program a SPI ROM onboard a
PCI card that is connected to your ARM SoC.

3. For those who wish to try this code on Seaboard, please be aware that the
UART is disabled during operation and then re-enabled afterward. This is
because the MISO/MOSI are muxed with the UART (See comments in
tegra2_spi.c). You will not see any Flashrom output on your serial console.

4. The tegra2_spi code was originally contributed by NVIDIA to the Chromium
OS U-Boot<http://git.chromium.org/gitweb/?p=chromiumos/third_party/u-boot.git;a=blob;f=drivers/spi/tegra2_spi.c;h=15a23124027ecdad5fcec23206a0fc67b968872d;hb=HEAD>
branch
and was later grafted into Flashrom so we could more easily perform SPI ROM
updates from userspace. Please excuse minor style inconsistencies as we are
trying to stay reasonably close to the code checked into the U-Boot tree ;-)
Carl-Daniel Hailfinger - 2011-06-29 00:54:46
Am 28.06.2011 01:52 schrieb David Hendricks:
> This patch set makes Flashrom a bit more ARM-friendly and adds raw Tegra2
> SPI controller support. It isolates a few PCI-isms, adds some low-level
> hardware access stubs, adds Tegra2 processor detection, and adds Tegra2 raw
> SPI controller code.
>   

Nice!


> I've attached some logfiles for read/erase/write operations. This particular
> patch set was tested using a board based off NVIDIA's Tegra2 reference board
> ("Seaboard"). Earlier revisions were tested on a Seaboard.
>
> All three attached patches are:
> Signed-off-by: David Hendricks <dhendrix@google.com>
>
> Much of the original U-Boot --> Flashrom porting work was done by Stefan
> Reinauer <reinauer@google.com>, and the FIFO code updated / fixed up by
> Louis Lo <yjlou@google.com>.
>
> A few notes:
> 1. A few programmers must be disabled due to reliance on PCI. You can hack
> up your Makefile or compile with "CONFIG_RAYER_SPI=no CONFIG_NIC3COM=no
> CONFIG_NICREALTEK=no CONFIG_SATAMV=no".
>   

Actually, it is a requirement for PCI port I/O space (well, the
non-memmapped space specified in the PCI standard, usually accesses with
in[bwl]/out[bwl] functions). We ought to detect unavailability of that
at compile time, preferably in the Makefile.


> 2. Due to issues with libpci, you can't use the same binary on machines with
> PCI and without PCI. So for example, you can't program a SPI ROM onboard a
> PCI card that is connected to your ARM SoC.
>   

Could you explain more? IIRC some people were using flashrom on ARM
(independent patch) with PCI support. Not calling any PCI functions
should be enough to avoid any and all interactions between libpci and
the hardware.


> 4. The tegra2_spi code was originally contributed by NVIDIA to the Chromium
> OS U-Boot<http://git.chromium.org/gitweb/?p=chromiumos/third_party/u-boot.git;a=blob;f=drivers/spi/tegra2_spi.c;h=15a23124027ecdad5fcec23206a0fc67b968872d;hb=HEAD>
> branch
> and was later grafted into Flashrom so we could more easily perform SPI ROM
> updates from userspace. Please excuse minor style inconsistencies as we are
> trying to stay reasonably close to the code checked into the U-Boot tree ;-)
>   

Ah, that explains some of the quirks I saw.

Could you explain the Tegra2 hardware a bit more? The code suggests that
it is more or less a slightly intelligent bitbanging controller with a
"special" programing interface.


At a first glance, the following issues stick out:
1-3-isolate_pci_isms.patch
This essentially declares ARM a no-PCI zone. That's OK for testing, but
not for merge. What exactly is the problem with PCI probing here? Does
it return errors? Does it crash or terminate the application? Does it
mess with the machine in ways which might cause breakage?

2-3-add_arm_isms.patch
Have you checked with an architecture guru that sync_primitive() can
really be empty, not only for that arch in general, but also for
accesses to a mmapped region the way flashrom does it?

3-3-add_tegra2_spi_controller.patch
Not your fault, but we really need a way to detect the target
architecture in the Makefile. The issues of which SPI masters to include
for internal exists on all architectures. Any ideas? I experimented with
uname calls in the past, but that checks the host arch, not the target
arch. Grepping the preprocessor output for the compiler might be an option.
echo|gcc -dM -E -|grep "whatever\|arch\|defines"
Or you try this pretty straightforward solution:

Create a file arch.h with these contents:
#if defined (__i386__)
#define __FLASHROM_ARCH__ "x86"
#elif defined (__x86_64__)
#define __FLASHROM_ARCH__ "x86_64"
#elif defined (__mips) || defined (__mips__) || defined (_mips) ||
defined (mips)
#define __FLASHROM_ARCH__ "mips"
#elif defined(__powerpc__) || defined(__powerpc64__) || defined(__ppc__)
|| defined(__ppc64__)
#define __FLASHROM_ARCH__ "ppc"
#endif
__FLASHROM_ARCH__

Then run
gcc -E arch.h|grep -v ^#
The result on my machine will be
"x86"
Side note: Such an arch.h file (with some extensions) might save us from
having to check every possible arch define everywhere we need to
differentiate between architectures.

I will comment on the Tegra2 SPI driver later, we should get the
infrastructure questions addressed first.

Regards,
Carl-Daniel
Stefan Reinauer - 2011-06-29 01:32:13
On Tue, Jun 28, 2011 at 5:54 PM, Carl-Daniel Hailfinger
<c-d.hailfinger.devel.2006@gmx.net> wrote:


>> 2. Due to issues with libpci, you can't use the same binary on machines with
>> PCI and without PCI. So for example, you can't program a SPI ROM onboard a
>> PCI card that is connected to your ARM SoC.
>
> Could you explain more? IIRC some people were using flashrom on ARM
> (independent patch) with PCI support. Not calling any PCI functions
> should be enough to avoid any and all interactions between libpci and
> the hardware.

One of the problems is that if you call libpci's init function on a
system with no PCI support, libpci will not return an error but just
end the program right away. This makes it hard to have one binary that
works on PCI and non-PCI ARM systems.

Stefan
Carl-Daniel Hailfinger - 2011-06-29 02:39:10
Am 29.06.2011 03:32 schrieb Stefan Reinauer:
> On Tue, Jun 28, 2011 at 5:54 PM, Carl-Daniel Hailfinger
> <c-d.hailfinger.devel.2006@gmx.net> wrote:
>
>
>   
>>> 2. Due to issues with libpci, you can't use the same binary on machines with
>>> PCI and without PCI. So for example, you can't program a SPI ROM onboard a
>>> PCI card that is connected to your ARM SoC.
>>>       
>> Could you explain more? IIRC some people were using flashrom on ARM
>> (independent patch) with PCI support. Not calling any PCI functions
>> should be enough to avoid any and all interactions between libpci and
>> the hardware.
>>     
> One of the problems is that if you call libpci's init function on a
> system with no PCI support, libpci will not return an error but just
> end the program right away. This makes it hard to have one binary that
> works on PCI and non-PCI ARM systems.
>   

Just set pci_access->error to a function with printf signature (e.g.
my_libpci_error_interceptor) before calling pci_init and make sure
my_libpci_error_interceptor sets a global variable pci_failed=1 once it
is called.

That is ugly, but it should work.

Regards,
Carl-Daniel

Patch

Index: flashrom-tegra2/Makefile
===================================================================
--- flashrom-tegra2.orig/Makefile
+++ flashrom-tegra2/Makefile
@@ -223,7 +223,10 @@  ifeq ($(CONFIG_INTERNAL), yes)
 FEATURE_CFLAGS += -D'CONFIG_INTERNAL=1'
 PROGRAMMER_OBJS += processor_enable.o chipset_enable.o board_enable.o cbtable.o dmi.o internal.o
 # FIXME: The PROGRAMMER_OBJS below should only be included on x86.
+# FIXME: unify XXXspi.o and XXX_spi.o naming conventions. spi/XXX.o?
 PROGRAMMER_OBJS += it87spi.o it85spi.o ichspi.o sb600spi.o wbsio_spi.o mcp6x_spi.o
+# FIXME: The PROGRAMMER_OBJS below should only be included on ARM
+PROGRAMMER_OBJS += tegra2_spi.o
 NEED_PCI := yes
 endif
 
Index: flashrom-tegra2/tegra2_spi.c
===================================================================
--- /dev/null
+++ flashrom-tegra2/tegra2_spi.c
@@ -0,0 +1,405 @@ 
+/*
+ * This file is part of the flashrom project.
+ *
+ * Copyright (C) 2010 NVIDIA Corporation
+ * Copyright (C) 2011 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; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * 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
+ */
+
+#if defined(__arm__)
+#include <assert.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include "flash.h"
+#include "programmer.h"
+#include "tegra2_spi.h"
+
+static void *gpio_base, *clkrst_base, *apbmisc_base, *spi_base;
+
+#define SPI_TIMEOUT 50000  /* 100ms = 50000 * 2us */
+
+/* On Seaboard: GPIO_PI3 = Port I = 8, bit = 3 */
+#define UART_DISABLE_PORT 8
+#define UART_DISABLE_BIT 3
+
+/* Config port:bit as GPIO, not SFPIO (default) */
+static void __set_config(unsigned port, unsigned bit, int type)
+{
+	u32 u;
+
+	msg_pdbg("%s: port = %d, bit = %d, %s\n", __func__,
+	         port, bit, type ? "GPIO" : "SFPIO");
+
+	u = mmio_readl(GPIO_CNF(port));
+	if (type)  /* GPIO */
+		u |= 1 << bit;
+	else
+		u &= ~(1 << bit);
+	rmmio_writel(u, GPIO_CNF(port));
+}
+
+/* Config GPIO port:bit as input or output (OE) */
+static void __set_direction(unsigned port, unsigned bit, int output)
+{
+	u32 u;
+
+	msg_pdbg("%s: port = %d, bit = %d, %s\n", __func__,
+	         port, bit, output ? "OUT" : "IN");
+
+	u = mmio_readl(GPIO_OE(port));
+	if (output)
+		u |= 1 << bit;
+	else
+		u &= ~(1 << bit);
+	rmmio_writel(u, GPIO_OE(port));
+}
+
+/* set GPIO OUT port:bit as 0 or 1 */
+static void __set_level(unsigned port, unsigned bit, int high)
+{
+	u32 u;
+
+	msg_pdbg("%s: port = %d, bit %d == %d\n", __func__,
+	         port, bit, high);
+
+	u = mmio_readl(GPIO_OUT(port));
+	if (high)
+		u |= 1 << bit;
+	else
+		u &= ~(1 << bit);
+	rmmio_writel(u, GPIO_OUT(port));
+}
+
+/* set GPIO port:bit as an output, with polarity 'value' */
+static int tg2_gpio_direction_output(unsigned port, unsigned bit, int value)
+{
+	msg_pdbg("%s: port = %d, bit = %d, value = %d\n",
+	         __func__, port, bit, value);
+
+	/* Configure as a GPIO */
+	__set_config(port, bit, 1);
+
+	/* Configure GPIO output value. */
+	__set_level(port, bit, value);
+
+	/* Configure GPIO direction as output. */
+	__set_direction(port, bit, 1);
+
+	return 0;
+}
+
+static void spi_cs_activate(void)
+{
+	uint32_t *spi_cmd = (uint32_t *)spi_base;
+
+	/*
+	 * CS is negated on Tegra, so drive a 1 to get a 0
+	 */
+	mmio_writel(mmio_readl(spi_cmd) | SPI_CMD_CS_VAL, spi_cmd);
+	msg_pspew("%s: CS driven %s\n", __func__,
+	          (mmio_readl(spi_cmd) & SPI_CMD_CS_VAL) ? "LOW" : "HIGH");
+}
+
+static void spi_cs_deactivate(void)
+{
+	uint32_t *spi_cmd = (uint32_t *)spi_base;
+
+
+	/*
+	 * CS is negated on Tegra, so drive a 0 to get a 1
+	*/
+	mmio_writel(mmio_readl(spi_cmd) & ~SPI_CMD_CS_VAL, spi_cmd);
+	msg_pspew("%s: CS driven %s\n", __func__,
+	          (mmio_readl(spi_cmd) & SPI_CMD_CS_VAL) ? "LOW" : "HIGH");
+}
+
+/* Helper function to calculate the clock cycle in this round.
+ * Also updates the byte count remaining to be used this round.
+ *
+ * For example, we want to write 6 bytes to SPI and then read 5 bytes back.
+ *
+ * +---+---+---+---+---+---+
+ * | W | W | W | W | W | W |
+ * +---+---+---+---+---+---+---+---+---+---+---+
+ *                         | R | R | R | R | R |
+ *                         +---+---+---+---+---+
+ * |<-- round 0 -->|
+ *                 |<-- round 1 -->|
+ *                                 |<-- round 2 -->|
+ *
+ * So that the continuous calling this function would get:
+ *
+ * round| RET| writecnt  readcnt  bits  to_write  to_read
+ * -----+----+---------------------------------------------
+ * INIT |    |     6        5
+ *    0 |  1 |     2        5      32       4        0
+ *    1 |  1 |     0        3      32       2        2
+ *    2 |  1 |     0        0      24       0        3
+ *    3 |  0 |     -        -       -       -        -
+ *
+ */
+int next4Bytes(uint32_t *writecnt, uint32_t *readcnt, int *num_bits,
+               uint32_t *to_write, uint32_t *to_read) {
+	assert(writecnt);
+	assert(readcnt);
+	assert(num_bits);
+	assert(to_write);
+	assert(to_read);
+
+	*to_write = min(*writecnt, 4);
+	*to_read = min(*readcnt, 4 - *to_write);
+
+	*writecnt -= *to_write;
+	*readcnt -= *to_read;
+
+	*num_bits = (*to_write + *to_read) * 8;
+
+	if (*num_bits)
+		return 1;  /* need to be called again. */
+	else
+		return 0;  /* handled write and read requests. */
+}
+
+/*
+ * Tegra2 FIFO design is ... interesting. For example, you want to Tx 2 bytes:
+ *
+ *                +---+---+
+ *    writearr[]: | 0 | 1 |
+ *                +---+---+
+ *                    \   \
+ *                     \   \
+ *                      \   \
+ *                       \   \
+ *                        \   \
+ *             31 +---+---+---+---+ 0
+ *  tmp(32-bits): | X | X | 0 | 1 |
+ *                +---+---+---+---+ LSB
+ *
+ * It is neither little or big endian. The first bit for SPI controller to
+ * transfer is the bit 15 in FIFO, neither bit 31 or bit 0, because the transfer
+ * length is 16 bits (2 bytes).
+ *
+ * Rx follows the similar rule. First bit comes at bit 0, and the whole FIFO
+ * left-shifts 1 bit for every bit comes in. Hence, after reading 3 bytes,
+ * the first coming bit will reside in bit 23.
+ */
+int tegra2_spi_send_command(unsigned int writecnt,
+                            unsigned int readcnt,
+                            const unsigned char *writearr,
+                            unsigned char *readarr)
+{
+	int retval = 0;
+	uint8_t *delayed_msg = NULL;  /* for UART is disabled. */
+	uint32_t *spi_cmd = (uint32_t *)spi_base;
+	uint32_t *spi_sts = (uint32_t *)(spi_base + 0x04);
+	uint32_t *tx_fifo = (uint32_t *)(spi_base + 0x10);
+	uint32_t *rx_fifo = (uint32_t *)(spi_base + 0x20);
+	uint32_t status;
+	uint32_t to_write, to_read;  /*  byte counts to fill FIFO. */
+	uint32_t bits;  /* bit count to tell SPI controller. */
+
+	mmio_writel(mmio_readl(spi_sts), spi_sts);
+	mmio_writel(mmio_readl(spi_cmd) | SPI_CMD_TXEN | SPI_CMD_RXEN, spi_cmd);
+	spi_cs_activate();
+
+	while (next4Bytes(&writecnt, &readcnt, &bits, &to_write, &to_read)) {
+		int i;
+		uint32_t tmp;
+		uint32_t tm;  /* timeout counter */
+
+		/* prepare Tx FIFO */
+		for (tmp = 0, i = 0; i < to_write; ++i) {
+			tmp |= (*writearr++) << ((bits / 8 - 1 - i) * 8);
+		}
+		mmio_writel(tmp, tx_fifo);
+
+		/* Kick the SCLK running: Shift out TX FIFO, and receive RX. */
+		mmio_writel(mmio_readl(spi_cmd) & ~SPI_CMD_BIT_LENGTH_MASK,
+		            spi_cmd);
+		mmio_writel(mmio_readl(spi_cmd) | (bits - 1),
+		            spi_cmd);
+		mmio_writel(mmio_readl(spi_cmd) | SPI_CMD_GO, spi_cmd);
+
+		/* Wait for controller completes the task. */
+		for (tm = 0; tm < SPI_TIMEOUT; ++tm) {
+			if (((status = mmio_readl(spi_sts)) &
+			    (SPI_STAT_BSY | SPI_STAT_RDY)) == SPI_STAT_RDY)
+				break;
+			/* We setup clock to 6MHz, so that we shall come back
+			 * after: 1 / (6MHz) * 8 bits = 1.333us
+			 */
+			programmer_delay(2);
+		}
+		mmio_writel(mmio_readl(spi_sts) | SPI_STAT_RDY, spi_sts);
+
+		/* Since the UART is disabled here, we delay printing the
+		 * message until spi_cs_deactivate() is called.
+		 */
+		if (tm >= SPI_TIMEOUT) {
+			static uint8_t err[256];
+			retval = -1;
+			snprintf(err, sizeof(err),
+			         "%s():%d BSY&RDY timeout, status = 0x%08x\n",
+			         __func__, __LINE__, status);
+			delayed_msg = err;
+			break;
+		}
+
+		/* read RX FIFO */
+		tmp = mmio_readl(rx_fifo);
+		for (i = 0; i < to_read; ++i) {
+			*readarr++ = (tmp >> ((to_read - 1 - i) * 8)) & 0xFF;
+		}
+	}
+
+	mmio_writel(status = mmio_readl(spi_sts), spi_sts);
+
+	spi_cs_deactivate();
+	if (delayed_msg) {
+		msg_perr("%s\n", delayed_msg);
+	}
+
+	return retval;
+}
+
+int tegra2_spi_read(struct flashchip *flash, uint8_t *buf, int start, int len)
+{
+	return spi_read_chunked(flash, buf, start, len,
+	                        spi_programmer->max_data_read);
+}
+
+int tegra2_spi_write(struct flashchip *flash, uint8_t *buf, int start, int len)
+{
+	return spi_write_chunked(flash, buf, start, len,
+	                         spi_programmer->max_data_write);
+}
+
+/* Unmap register spaces */
+int tegra2_spi_shutdown(void *data)
+{
+	physunmap(gpio_base, 4096);
+	physunmap(clkrst_base, 4096);
+	physunmap(apbmisc_base, 4096);
+	physunmap(spi_base - 0x380, 4096);
+	return 0;
+}
+
+static const struct spi_programmer spi_programmer_tegra2 = {
+	.type = SPI_CONTROLLER_TEGRA2,
+	/* FIFO depth is 32, packets can be up to 32-bits in length. */
+	.max_data_read = 128,
+	.max_data_write = 128,
+	.command = tegra2_spi_send_command,
+	.multicommand = default_spi_send_multicommand,
+	.read = tegra2_spi_read,
+	.write_256 = tegra2_spi_write,
+};
+
+/* Map register spaces */
+int tegra2_spi_init(void)
+{
+	u32 val;
+	uint32_t *spi_cmd;
+	uint32_t *spi_sts;
+
+	buses_supported = CHIP_BUSTYPE_SPI;
+	register_spi_programmer(&spi_programmer_tegra2);
+
+	gpio_base = physmap("GPIO", TEGRA2_GPIO_BASE, 4096);
+	clkrst_base = physmap("CLK/RST", NV_ADDRESS_MAP_PPSB_CLK_RST_BASE,
+	                      4096);
+	apbmisc_base = physmap("APB MISC", NV_ADDRESS_MAP_APB_MISC_BASE, 4096);
+	/* non-page offset */
+	spi_base = physmap("SPI", TEGRA2_SPI_BASE - 0x380, 4096) + 0x380;
+
+	register_shutdown(tegra2_spi_shutdown, NULL);
+
+	flashbase = 0;  /* FIXME: to make sanity check happy. */
+
+	/* Init variables */
+	spi_cmd = (uint32_t *)spi_base;
+	spi_sts = (uint32_t *)(spi_base + 0x04);
+
+	/*
+	 * SPI reset/clocks init - reset SPI, set clocks, release from reset
+	 */
+
+	/* SWE_SPI1_RST: Hold SPI controller 1 in reset */
+	val = mmio_readl(clkrst_base + 0x08) | 0x800;
+	rmmio_writel(val, (clkrst_base + 0x08));
+	msg_pdbg("%s: ClkRst = %08x\n", __func__, val);
+
+	/* CLK_ENB_SPI1: Enable clock to SPI 1 Controller */
+	val = mmio_readl(clkrst_base + 0x14) | 0x800;
+	rmmio_writel(val, (clkrst_base + 0x14));
+	msg_pdbg("%s: ClkEnable = %08x\n", __func__, val);
+
+	/* Change default SPI clock from 12MHz to 6MHz, same as BootROM */
+	val = mmio_readl(clkrst_base + 0x114) | 0x2;
+	rmmio_writel(val, (clkrst_base + 0x114));
+	msg_pdbg("%s: ClkSrc = %08x\n", __func__, val);
+
+	/* SWE_SPI1_RST: Clear SPI1 reset bit (take it out of reset),
+	 * use regular mmio_writel (restore callback already registered) */
+	val =  mmio_readl(clkrst_base + 0x08) & 0xFFFFF7FF;
+	mmio_writel(val, (clkrst_base + 0x08));
+	msg_pdbg("%s: ClkRst final = %08x\n", __func__, val);
+
+	/* Clear stale status here */
+	mmio_writel(SPI_STAT_RDY | SPI_STAT_RXF_FLUSH | SPI_STAT_TXF_FLUSH |
+	            SPI_STAT_RXF_UNR | SPI_STAT_TXF_OVF, spi_sts);
+	msg_pdbg("%s: STATUS = %08x\n", __func__, mmio_readl(spi_sts));
+
+	/*
+	 * Use sw-controlled CS, so we can clock in data after ReadID, etc.
+	 */
+	mmio_writel(mmio_readl(spi_cmd) | SPI_CMD_CS_SOFT, spi_cmd);
+	msg_pdbg("%s: COMMAND = %08x\n", __func__, mmio_readl(spi_cmd));
+
+	/*
+	 * SPI pins on Tegra2 are muxed - change pinmux last due to UART issue
+	 */
+	val = mmio_readl(apbmisc_base + 0x88) | 0xC0000000;
+	rmmio_writel(val, (apbmisc_base + 0x88));
+	msg_pdbg("%s: PinMuxRegC = %08x\n", __func__, val);
+
+	/* Set Z_LSPI to non-tristate mode */
+	val = mmio_readl(apbmisc_base + 0x20) & 0xFFFFFFFE;
+	rmmio_writel(val, (apbmisc_base + 0x20));
+	msg_pdbg("%s: TriStateReg = %08x\n", __func__, val);
+
+	/* delay 100ms so that all chars in buffer (1KB) can be flushed. */
+	programmer_delay(100000);
+
+	/*
+	 * We need to dynamically change the pinmux, shared w/UART RXD/CTS!
+	 */
+	val = mmio_readl(apbmisc_base + 0x84) | 0x0000000C;  /* 3 = SFLASH */
+	rmmio_writel(val, (apbmisc_base + 0x84));
+	msg_pdbg("%s: PinMuxRegB = %08x\n", __func__, val);
+
+	/* On Seaboard, MOSI/MISO are shared w/UART.
+	 * Use GPIO I3 (UART_DISABLE) to tristate UART during SPI activity.
+	 * Enable UART later (cs_deactivate) so we can use it for U-Boot comms.
+	 */
+	msg_pdbg("%s: DISABLING UART!\n", __func__);
+	tg2_gpio_direction_output(UART_DISABLE_PORT, UART_DISABLE_BIT, 1);
+
+	return 0;
+}
+#endif
Index: flashrom-tegra2/tegra2_spi.h
===================================================================
--- /dev/null
+++ flashrom-tegra2/tegra2_spi.h
@@ -0,0 +1,81 @@ 
+/*
+ * This file is part of the flashrom project.
+ *
+ * Copyright (C) 2010 NVIDIA Corporation
+ * Copyright (C) 2011 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; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * 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 __TEGRA2_SPI_H__
+#define __TEGRA2_SPI_H__
+
+// ***************************************************************************
+// Hardware BARs
+
+#define TEGRA2_GPIO_BASE			0x6000D000
+#define TEGRA2_SPI_BASE				0x7000C380
+#define NV_ADDRESS_MAP_PPSB_CLK_RST_BASE	0x60006000
+#define NV_ADDRESS_MAP_APB_MISC_BASE		0x70000000
+
+// ***************************************************************************
+// Clock/reset controller
+#define CLK_RST_ENB_H_0_OFFSET  0x14
+#define CLK_RST_ENB_H_0_SPI1    (1 << 11)
+
+// ***************************************************************************
+// GPIO controller
+
+#define GPIO_OFF(port)		(((port / 4) * 128) + ((port % 4) * 4))
+#define GPIO_CNF(port)		(gpio_base + GPIO_OFF(port) + 0x00)
+#define GPIO_OE(port)		(gpio_base + GPIO_OFF(port) + 0x10)
+#define GPIO_OUT(port)		(gpio_base + GPIO_OFF(port) + 0x20)
+#define GPIO_IN(port)		(gpio_base + GPIO_OFF(port) + 0x30)
+#define GPIO_INT_STA(port)	(gpio_base + GPIO_OFF(port) + 0x40)
+#define GPIO_INT_ENB(port)	(gpio_base + GPIO_OFF(port) + 0x50)
+#define GPIO_INT_LVL(port)	(gpio_base + GPIO_OFF(port) + 0x60)
+#define GPIO_INT_CLR(port)	(gpio_base + GPIO_OFF(port) + 0x70)
+
+#define	SPI_CMD_GO		(1 << 30)
+#define	SPI_CMD_ACTIVE_SCLK	(1 << 26)
+#define	SPI_CMD_CK_SDA		(1 << 21)
+#define	SPI_CMD_ACTIVE_SDA	(1 << 18)
+#define	SPI_CMD_CS_POL		(1 << 16)
+#define	SPI_CMD_TXEN		(1 << 15)
+#define	SPI_CMD_RXEN		(1 << 14)
+#define	SPI_CMD_CS_VAL		(1 << 13)
+#define	SPI_CMD_CS_SOFT		(1 << 12)
+#define	SPI_CMD_CS_DELAY	(1 << 9)
+#define	SPI_CMD_CS3_EN		(1 << 8)
+#define	SPI_CMD_CS2_EN		(1 << 7)
+#define	SPI_CMD_CS1_EN		(1 << 6)
+#define	SPI_CMD_CS0_EN		(1 << 5)
+#define	SPI_CMD_BIT_LENGTH	(1 << 4)
+#define	SPI_CMD_BIT_LENGTH_MASK	0x0000001F
+
+#define	SPI_STAT_BSY		(1 << 31)
+#define	SPI_STAT_RDY		(1 << 30)
+#define	SPI_STAT_RXF_FLUSH	(1 << 29)
+#define	SPI_STAT_TXF_FLUSH	(1 << 28)
+#define	SPI_STAT_RXF_UNR	(1 << 27)
+#define	SPI_STAT_TXF_OVF	(1 << 26)
+#define	SPI_STAT_RXF_EMPTY	(1 << 25)
+#define	SPI_STAT_RXF_FULL	(1 << 24)
+#define	SPI_STAT_TXF_EMPTY	(1 << 23)
+#define	SPI_STAT_TXF_FULL	(1 << 22)
+#define	SPI_STAT_SEL_TXRX_N	(1 << 16)
+#define	SPI_STAT_CUR_BLKCNT	(1 << 15)
+
+#endif	/* __TEGRA2_SPI_H__ */
Index: flashrom-tegra2/programmer.h
===================================================================
--- flashrom-tegra2.orig/programmer.h
+++ flashrom-tegra2/programmer.h
@@ -523,6 +523,9 @@  enum spi_controller {
 	SPI_CONTROLLER_VIA,
 	SPI_CONTROLLER_WBSIO,
 #endif
+#if defined(__arm__)
+	SPI_CONTROLLER_TEGRA2,
+#endif
 #endif
 #if CONFIG_FT2232_SPI == 1
 	SPI_CONTROLLER_FT2232,
@@ -588,6 +591,13 @@  int mcp6x_spi_init(int want_spi);
 /* sb600spi.c */
 int sb600_probe_spi(struct pci_dev *dev);
 
+/* tegra2_spi.c */
+int tegra2_spi_init(void);
+int tegra2_spi_send_command(unsigned int writecnt, unsigned int readcnt,
+		      const unsigned char *writearr, unsigned char *readarr);
+int tegra2_spi_read(struct flashchip *flash, uint8_t *buf, int start, int len);
+int tegra2_spi_write(struct flashchip *flash, uint8_t *buf, int start, int len);
+
 /* wbsio_spi.c */
 int wbsio_check_for_spi(void);
 #endif
Index: flashrom-tegra2/processor_enable.c
===================================================================
--- flashrom-tegra2.orig/processor_enable.c
+++ flashrom-tegra2/processor_enable.c
@@ -81,6 +81,48 @@  static int is_loongson(void)
 }
 #endif
 
+#if defined(__arm__)
+#include <stdio.h>
+#include <string.h>
+#include <ctype.h>
+
+/* Returns true if the /proc/cpuinfo contains a line: "CPU part *: *0xc09".
+ * TODO: need to extend in future for same SPI controller in chip family.
+ */
+static int is_tegra2(void)
+{
+	FILE *cpuinfo;
+	uint32_t impl = 0, architecture = 0, variant = 0, part = 0;
+	const char *name = "CPU part";
+	const char *value = "0xc09";
+	int ret = 0;
+
+	cpuinfo = fopen("/proc/cpuinfo", "rb");
+	if (!cpuinfo)
+		return 0;
+	while (!feof(cpuinfo)) {
+		char line[512], *ptr;
+		if (fgets(line, sizeof(line), cpuinfo) == NULL)
+			break;
+		ptr = line;
+		while (*ptr && isspace((unsigned char)*ptr))
+			ptr++;
+		if (strncmp(ptr, name, strlen(name)) == 0)
+			ptr += strlen(name);
+		while (*ptr && isspace((unsigned char)*ptr))
+			ptr++;
+		if (*ptr != ':')
+			continue;
+		ptr++;
+		while (*ptr && isspace((unsigned char)*ptr))
+			ptr++;
+		ret = (strncmp(ptr, value, strlen(value)) == 0);
+	}
+	fclose(cpuinfo);
+	return ret;
+}
+#endif
+
 int processor_flash_enable(void)
 {
 	/* FIXME: detect loongson on FreeBSD and OpenBSD as well.  */
@@ -90,6 +132,13 @@  int processor_flash_enable(void)
 		return 0;
 	}
 #endif
+
+#if defined (__arm__)
+	if (is_tegra2()) {
+		msg_pdbg("Detected NVIDIA Tegra 2.\n");
+		return tegra2_spi_init();
+	}
+#endif
 	/* Not implemented yet. Oh well. */
 	return 1;
 }